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[Display omitted] • Introduced metal-catechol groups to adsorb SO 2 in UiO-66, HBU-20, and MFM-601. • MOFs with different pore types have different abilities to adsorb SO 2 molecules at different partial pressures and temperatures. • Significantly improved adsorption performance of Cat(Cu)-UiO-66 and Cat(Cu)-MFM-601. Sulfur dioxide (SO 2) is a polluting gas that poses a significant threat to the environment and human health. Adsorption and removal of SO 2 is an effective means in its control process, and MOFs have garnered widespread attention due to their immense potential in the field of gas adsorption. In this paper, the adsorption process of SO 2 in the pore structures of three Zr-based MOF materials, UiO-66, MFM-601, and HBU-20, was firstly simulated based on MD and GCMC. The ability of different pore structures to adsorb SO 2 gas at varying temperatures and pressures was analyzed with emphasis. Subsequently, the three MOFs were modified by introducing metal-catechol into each of them. The effect of Cat(M) (M = Cr, Mn, Fe, Ni, Cu, Zn) on the SO 2 adsorption properties of the MOF materials was deeply analyzed based on DFT. The results indicated that the introduction of Cat(M) significantly enhanced the adsorption capacity of UiO-66 and MFM-601 for SO 2. Notably, UiO-66-Cat(Cu) and MFM-601-Cat(Cu) exhibited the most significant enhancement effects, reaching 30.8 % and 102.7 %, at room temperature and pressure. Furthermore, Cat(M) enhanced the thermal stability of UiO-66 and MFM-601. These findings hold guiding significance for the study of MOF modification for the removal of SO 2 gas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Euchlorine-based WOS completely removes NO x on top of SO x. • SO 2 plays a synergistic role in NO x absorption. • Acidity promotes a gas–liquid dual oxidation making the de-NO x process more efficient. • WOS under acidic conditions saves 83% chemical and 70% water. • WOS can be a viable alternative to the conventional FGD-SCR plants. This paper reports the performances of a pilot-scale Wet Oxidative Scrubber (WOS) in the treatment of a simulated flue-gas containing 500 ppm v SO 2 and 1030 ppm v NO x and operated at 60 °C and 1 atm. The scrubber is fed with an oxidizing solution containing NaClO 2 at either 0.75 % or 1 % w/w initially at pH > 9 and then acidified to pH down to 3 with HCl, to obtain the additional oxidative contribution given by euchlorine species during the simultaneous absorption. Further experiments of single-component NO x absorption are performed to better understand the role exerted by SO 2 in the simultaneous absorption. These experimental tests are carried out to investigate the effect of the acidity of the chlorite-based scrubbing solution on the simultaneous absorption performance of SO 2 and NO x , highlighting the intensification with respect to the bare de-NO x system. Experiments also allow determining the optimal dosages and solution pH for a complete and optimized removal of NO x and SO x also being less energy-intensive. For a scrubbing solution under acid-induced conditions (pH = 3), the retrieved results show that the NaClO 2 molar dosage needed for a complete simultaneous removal results 3.6 times greater than the total NO x concentration in the flue-gas. This allows an interesting reduction of 83 % in oxidant consumption and a water-saving of 70 % with respect to the same process applied to the simultaneous NO x absorption but without altering the solution pH. Overall, the results confirm the enhancing role exerted by euchlorine deriving from chlorite acidification and sulfur dioxide presence in the flue-gas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al 2 O 3 was coated on Cu-SAPO-34 by chemical liquid deposition. • Al 2 O 3 shell reacted with SO 2 and protected the active sites of catalysts. • Al 2 O 3 shell suppressed the aggregation of Cu2+ after hydrothermal aging. • Structural dealumination of Cu-SAPO-34 was suppressed after Al 2 O 3 coating. Cu-based zeolites are one kind of efficient catalyst in the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) in diesel exhaust, but the SO 2 resistance and hydrothermal stability of the catalyst need to be improved. Herein, in this work, a series of Al 2 O 3 -coated Cu-SAPO-34 catalysts were prepared by chemical liquid deposition (CLD) to enhance the SO 2 resistance and hydrothermal stability simultaneous. The optimal Al 2 O 3 -coated Cu-SAPO-34 catalyst showed >90 % NO conversion at 180–500 °C, and presented significant enhanced SO 2 resistance and hydrothermal stability in comparison to the uncoated Cu-SAPO-34 catalyst. It was found that the Al 2 O 3 shell served as the sacrificial layer, reacted with SO 2 , which could limit the competitive adsorption between SO 2 and NO on the Cu-SAPO-34, and reduce the formation of sulfate species. Moreover, the Al 2 O 3 shell also limited the aggregation of Cu species and enhanced the stability of the catalysts during hydrothermal aging. This work provides a facile method for construction of efficient practical NH 3 -SCR catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption amount of SO 2 increases following a power function with time. • A low pressure drop of the ACC sample is observed as 8.7 Pa/mm at a filtration velocity of 0.45 m/s. • Raising filtration velocity promotes initial mass transfer more dramatically than concentration. • A twin-model method for predicting filter's adsorption performance is proposed. The removal of SO 2 contaminant from the cathode air is crucial for the improvement of the efficiency of high-power fuel cell. The SO 2 adsorption behaviour of dual-layer activated carbon cloth (ACC) was investigated at 5–15 ppm SO 2 and filtration velocities of 0.125–0.45 m/s. The adsorption amount increased following a power function with time. The equilibrium breakthrough rate declines from approx. 88% to 56% when the concentration drops from 20 ppm to 5 ppm at 0.26 m/s and reduces from approx. 81% to 59% as the filtration velocity decreases from 0.45 m/s to 0.125 m/s at 10 ppm of SO 2. In comparison to the packed bed filter, the pressure drop per thickness of the ACC media was considerably lower, measuring less than 9 Pa/mm, which can effectively decrease the parasitic power of the air supply unit. To determine filter's breakthrough time and adsorption amount for the real application condition, a prediction method coupling the Yoon-Nelson model and the adsorption amount prediction model has been developed. The model can predict the breakthrough time and the adsorption amount of the full-scale filter using low-cost performance test data from the ACC materials with less than 10% error. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/Al-doped MnO x catalysts synthesized by solvothermal method. • Fe/Al doping improved the SCR activity and N 2 selectivity of MnO x catalysts. • Improved redox capability of MnFeO x enhanced LT SCR activity and H 2 O/SO 2 resistance. • Thermal regeneration weakened metal-sulfate interactions in poisoned MnFeO x. • MnFeO x exhibited higher thermal regenerability than MnAlO x. Fe-doped MnO x catalyst prepared by a preferred solvothermal method displayed noticeably better low-temperature (LT) NH 3 -SCR performance and water stability than an analogously prepared Al-doped MnO x catalyst. The SCR activity of both catalysts decreased markedly when exposed to SO 2 , but the resultant MnFeO x -S catalyst retained higher LT activity than MnAlO x -S and recovered significantly more of its original activity after thermal regeneration (400 °C). Comprehensive characterization confirmed that the deactivation of the catalysts was governed by formation of stable metal sulfates, which only decomposed to a minor extent upon thermal treatment although Al doping lowered the thermal stability of the adsorbed sulfur species. Additionally, Fe doping was found to facilitate electron transfer between Mn and Fe ions and weaken the interaction between active sites and deposited sulfates during the heating procedure, which promoted re-oxidation of Mn2+ to catalytically active Mn3+/Mn4+. Altogether, the altered redox properties resulted in improved LT SCR performance, enhanced water stability, higher SO 2 tolerance and superior regeneration of the MnFeO x catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • The presence of SO 2 affects the bonding ability between chlorine atoms and alkali metals. • The presence of H 2 O can enhance the adsorption of NaHCO 3 to HCl. • Understanding of the competitive adsorption mechanism between HCl and SO 2. The utilization of sodium bicarbonate (NaHCO 3) as a solid reactant for the mitigation of acidic pollutants from industrial flue gas streams represents a straightforward and efficient process solution. The paper addresses the problem of medium- to high-temperature flue gas dechlorination by investigating the effects of base particle size, temperature, water vapour and different flue gas fractions on the removal of HCl from simulated flue gases by NaHCO 3 in a fixed-bed reactor, and the effects of the presence of SO 2 and H 2 O on the chlorination reactivity of NaHCO 3 are also investigated by density functional theory (DFT) calculations. The adsorption results implied that 300 °C was the optimum temperature for HCl removal by NaHCO 3 in a reaction system not affected by SO 2 or H 2 O; The higher the HCl concentration, the greater the HCl capture, but when the concentration is too high, due to the dense product layer makes the HCl gas molecules to the internal diffusion is blocked, the dechlorination effect becomes poor. The smaller the particle size of NaHCO 3 , the better the removal of HCl. In the system containing SO 2 , theoretical calculations based on density functional theory show that the presence of SO 2 affects the exchange of electrons between the Cl atoms in HCl and Na 2 CO 3 , and the bonding ability of the Na-Cl bond is weakened, thus weakening the dechlorination ability of Na 2 CO 3 ; However, SO 2 has little effect on HCl removal at the same concentration, due to the fact that HCl rapidly consumes the easily accessible surface of the absorber and SO 2 must diffuse deeper into the particles for the reaction to occur, suggesting a preferred reaction between HCl and NaHCO 3. After the addition of H 2 O, the adsorption energy of HCl on the surface of Na 2 CO 3 (2 0 0) was greater than the adsorption energy of SO 2 on the surface of Na 2 CO 3 (2 0 0), and HCl was preferentially adsorbed on the surface of Na 2 CO 3 (2 0 0), which preferentially reacted with the absorber. These findings help to elucidate the principle of HCl absorption by NaHCO 3 and the competition mechanism between HCl and SO 2 , and improve the theoretical knowledge of acid gas absorption by NaHCO 3. [ABSTRACT FROM AUTHOR]

• A two-stage air oxidation consisting of pre- and post-oxidation method was employed to prepare Mn-Fe doped porous biochar catalyst. • The S BET , pore property, Mn dispersity, redox ability and surface acidity of catalyst were comprehensively developed. • The catalyst showed highly enhanced NO conversion rate of 91.3% and desirable SO 2 and/or H 2 O resistance. • Two-stage air oxidation strengthened the synergistic interaction between Mn and Fe. • O-containing groups introduced by air oxidation promoted the adsorption of NH 3 and NO while decreased the adsorption of SO 2. In this study, a sustainable two-stage air oxidation (TAO) was employed to prepare Fe modified MnOx-biochar catalyst (C-O 2 -MF-O 2) instead of high temperature treatment and/or chemical activation for selective catalytic reduction of NO with NH 3 (NH 3 -SCR). The collaborative effect of Fe modification and TAO on the physicochemical properties and catalytic performance of catalysts was systematically studied. Compared with counterpart catalysts treated with two-stage N 2 (C-N 2 -MF-N 2) or one-stage O 2 (C-O 2 -MF-N 2 , C-N 2 -MF-O 2), C-O 2 -MF-O 2 showed obvious enhanced physicochemical properties (S BET , pore properties, high-valance metal ratio, chemisorption oxygen (O α) content), superior catalytic performance, achieving 91.3% NO conversion with nearly 100% N 2 selectivity at 150 °C, and much better H 2 O and SO 2 resistance. It is worth noting that TAO facilitated the redox performance of MnOx after Fe modification to generate more dispersed high-valance metal (Mn4+ and Fe3+), thereby favoring the low-temperature SCR activity of the catalyst. Further, the in situ DRIFTS studies revealed TAO produced remarkable effects on the adsorption behaviors of NH 3 , NO and SO 2 , and the corresponding mechanisms of catalyst activity enhancement and SO 2 resistance were proposed. Generally, TAO could be a favorable avenue to prepare catalysts with binary active metals for improving performance of NH 3 -SCR. [ABSTRACT FROM AUTHOR]

• Various synthetic methods for metal sulfides are introduced and compared. • Performances, merits, and flaws of metal sulfides are summarized and commented. • Layered metal sulfides, MoS 2 , WS 2 and SnS 2 , are the most promising mercury sorbents. • Effects of gas ingredients on the performances of metal sulfides are summed up. • Mercury capture mechanisms for metal sulfides are outlined and discussed. Mercury is largely emitted into the atmosphere during fossil fuel combustion or gasification, which causes a long-term contamination problem and poses great threats to human health. Currently, novel metal sulfides have been extensively investigated in capturing gaseous mercury because of their intense Hg0 affinities, large mercury uptakes, and distinguished tolerance to sulfur dioxide. This article overviews the recent progress on elemental mercury capture by diverse metal sulfides, i.e., CuS, ZnS, pyrite-phase metal sulfides, layered metal sulfides, Bi 2 S 3 and In 2 S 3. CuS and ZnS show good performances in a narrow temperature range due to the poor thermal stability and the compact crystal structure, respectively. Bi 2 S 3 and In 2 S 3 are also active in Hg0 adsorption, however, their performances are still unsatisfactory. Most pyrite-phase metal sulfides show moderate Hg0 capture abilities likely due to their compact crystal structures. Loading pyrites onto carriers or creating S vacancies in pyrite lattices seem to be feasible pathways to improve their performances. MoS 2 and WS 2 attained via molten salt method significantly outperform the ones obtained via hydrothermal method at elevated temperatures due to the production of ample sulfur variances and chemisorbed oxygen. Incorporating heteroatoms and expanding the interlayer distance by ions intercalation are effective routes to further strengthen their performances probably due to promoted electron transfer and increased accessibility of active sites, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO x -SiO 2 catalyst with good sulfur resistance and N 2 selectivity was prepared. • Doping of SiO 2 inhibited the adsorption of SO 2 and improved the sulfur resistance. • Doping of SiO 2 reduced the excessive oxidation of NH 3 and improved the N 2 selectivity. Manganese-based catalysts have excellent catalytic performance for the effective removal of NO x in low-temperature flue gas through selective catalytic reduction with NH 3 (NH 3 -SCR). However, the catalysts suffer from poor SO 2 resistance and N 2 selectivity in the actual process, which still need to be solved. In this study, MnO x -SiO 2 mixed oxide catalysts were designed and prepared by coprecipitation method to improve the SO 2 resistance and N 2 selectivity in NH 3 -SCR process. In the presence of 100 ppm SO 2 , MnO x -SiO 2 (0.72) catalyst showed excellent sulfur resistance with the conversion of NO x reached 95 % even after introducing SO 2 for 8 h. The doping of SiO 2 greatly improved the specific surface area and surface acidity of the catalyst, which was conducive to the adsorption of NH 3. Meanwhile, the redox performance of the catalyst was decreased, improving the N 2 selectivity. The study on the sulfur resistance mechanism revealed that the doping of SiO 2 reduced the adsorption of SO 2 on the surface of catalyst, protecting the active components and avoiding the accumulation of sulfates, thus achieving good sulfur resistance performance. This work provided an environmentally friendly NH 3 -SCR catalyst by inhibiting SO 2 adsorption to have good catalytic performance and SO 2 resistance. [ABSTRACT FROM AUTHOR]

• Activated carbons from petroleum coke have a high affinity for sulfur dioxide in both wet and dry experiments. • Sulfate formation on the active surface was not found to be significant. • Wet SO 2 experiments did not degrade the activated carbons through 10 thermal swing adsorption cycles. The removal of sulfur dioxide from flue gas is an important process for the mitigation of acid rain. Activated carbons have a low affinity for water and a high affinity for polarizable molecules, such as sulfur dioxide, making them good candidates for selective adsorbents for flue gases. This work presents results on the multicomponent adsorption of N 2 /CO 2 /SO 2 and N 2 /CO 2 /SO 2 /H 2 O flue gas mixtures on four activated carbons prepared from petroleum coke, and one carbon black. Multicomponent adsorption was measured at T = 30, 60, 90 °C. All five activated carbons had a high affinity and selectivity for SO 2 in both the presence and absence of water. The activated carbons prepared with KOH (P_K) and NaOH (P_Na) showed the highest capacity for SO 2 under wet conditions with thermal swing regeneration (P_K: n ads SO₂ = 0.148 ± 0.002 mmol g−1, P_Na: n ads SO₂ = 0.13 ± 0.01 mmol g−1). In pressure swing experiments of the wet flue gas mixture, the activated carbon prepared with a K 2 CO 3 and KOH (P_CK) (n ads SO₂ = 0.077 ± 0.002 mmol g−1) and P_K (n ads SO₂ = 0.064 ± 0.005 mmol g−1) activated carbons had the highest SO 2 capacities. Of the activated carbon, P_K had the greatest SO 2 /H 2 O selectivity for the thermal swing adsorption (T = 30 °C, S SO₂/H₂O = 3.0 ± 0.2) and pressure swing adsorption (T = 90 °C, S SO₂/H₂O = 3.9 ± 0.6) experiments. It was observed that activated carbons with higher carbon fraction were less likely to have a difference in SO 2 adsorption from dry versus wet conditions. After the wet SO 2 multicomponent adsorption, no change in the adsorption performance of any activated carbons was observed after 10 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sm can significantly enhance the SO 2 and H 2 O resistance of W-Zr catalyst. • Sm can preferentially react with SO 2 than chemisorbed oxygen. • The Sm species decreased the oxidation of SO 2 on the catalyst surface. • The Sm can effectively decrease the generation of ammonium sulfate species. The WO 3 -ZrO 2 for NH 3 -SCR catalyst has excellent NO conversion, especially at high temperature, which are appropriate for the diesel engine after-treatment system. However, the diesel engine NH 3 -SCR catalysts can be affected by SO 2 toxicity. Thus, a series of xSm-WZZ catalysts were prepared by sol–gel method, and the Sm species as the promoter were applied to enhancing the SO 2 resistance and regeneration performance of the catalyst. 1Sm-WZZ catalyst exhibited the best SO 2 and H 2 O resistance and slightly improved the NH 3 -SCR activity, in which 100% NO conversion and N 2 selectivity can be achieved at 400–600 ℃. Moreover, compared with WZZ catalyst, 1Sm-WZZ catalyst showed excellent regeneration performance, which could be regenerated by thermal treatment at 350 ℃. The results of XPS, CO 2 -TPD and H 2 -TPR revealed that the Sm could decrease the amount of alkaline sites and redox ability of catalyst, which may be the main reason for the reduction of the adsorption and oxidation of SO 2. Additionally, the Sm decreased the formation of ammonium sulfate salts on catalyst, which were verified by the TGA and FTIR spectrum experiments. Furthermore, the Sm could preferentially react with SO 2 than chemisorbed oxygen, which restrains the reaction of chemisorbed oxygen with SO 2 , thereby reducing the generation of sulfate around the chemisorbed oxygen. In addition, the in-situ DRIFTS tests indicated that the Sm could reduce the generation of S = O for tridentate sulfate species and SO 3 on the catalyst. [ABSTRACT FROM AUTHOR]

• The coupled response of coal oxidation and sodium reactions is studied. • Sodium species are scrutinized in both one- and two-dimensional flames. • Na, NaOH and NaCl drive the sodium chemical paths in coal flames. • HCl has a much stronger ability to react with sodium species than SO 2. Sodium emissions during pulverized-coal combustion (PCC) are known to result in severe ash-related operating issues of coal furnaces, e.g., fouling, slagging and corrosion. To relieve these issues and advance the clean utilization technologies of coal, a better understanding of the fundamental mechanisms driving the formation and transformation of the sodium species is required. In the present study, sodium emissions have been simulated in both one-dimensional (1D) premixed/diffusion flames of the coal volatile and an early-stage two-dimensional (2D) pulverized-coal flame. The properties of Loy Yang brown coal are used. The DRM22 skeletal mechanism is employed for volatile-gas combustion, and the reaction of sodium species is modeled by a detailed mechanism encompassing the elements Na, C, H, O, S and Cl. The compositions of the volatile fuels are obtained from the chemical percolation devolatilization (CPD) model, including CH 4 , C 2 H 2 , CO, H 2 , CO 2 and H 2 O. The initial species of Na, Cl and S in the volatile gas is set to be NaOH, HCl and SO 2 , respectively. The transformation characteristics of 12 sodium species are investigated in both the 1D volatile flames and the 2D pulverized-coal flame. The response of the sodium chemistry to volatile-gas combustion is analyzed under fuel-lean, stoichiometric and fuel-rich conditions. Na, NaOH and NaCl are found to be the major sodium species during the combustion. Parametric studies with HCl, SO 2 or both species removed from the volatile are then performed to investigate their effects on the sodium transformation characteristics in both the 1D and 2D flames. The results show that HCl has a much stronger ability to react with sodium species than SO 2. [ABSTRACT FROM AUTHOR]

• An iron-containing polyoxometalates as heterogeneous catalyst was firstly used in flue gas purification. • The catalyst has high activity for removal of SO 2 and NO in wider working pH range. • The reaction mechanism was proposed based on the characterizations and references. The simultaneous removal of SO 2 and NO from flue gas was firstly carried out by heterogeneous UV-Fenton-like process using Iron-containing polyoxometalates complex (denoted as FeIIIAspPW) as catalyst. The results showed that SO 2 achieved complete removal under all experimental conditions. The simultaneous removal efficiencies of 100% for SO 2 and 84.27% for NO were obtained under the established optimal experimental conditions. The main reaction products were identified as nitrate and sulfate based on the characterization of ion chromatography (IC) and material balance summary. Especially, the physicochemical properties of the fresh and spent catalyst were characterized systematically by a series of techniques, which manifested the stability of the catalyst and the existence of redox pair Fe3+/Fe2+ during the catalytic process. In combination with correlative references, the reaction mechanism was proposed, which stemmed from the chemisorption of H 2 O 2 by hydrogen bonding and the synergetic effect between the Fenton-like catalysis of ferric iron and photo-catalysis of PW 12 O 40 3− occurred on the surface of FeIIIAspPW. [ABSTRACT FROM AUTHOR]

• Fe and Co co-doped (Fe/Co = 2:4) Mn-Ce/TiO 2 exhibited higher SCR activity and excellent SO 2 resistance. • Reversible inhibition happened owe to the formation of (NH 4) 2 SO 4 or NH 4 HSO 4. • Irreversible deactivation of Mn-Ce/TiO 2 occurred by SO 2 due to the formation of high thermally stable sulfated species. • The uniform distribution of Fe and Co on the Mn-Ce/TiO 2 surface stopped SO 2 diffusing to the inner layer of catalyst. • NH 3 -SCR reaction over 2Fe4Co-MCT was mainly dominated by E-R mechanism in the presence of SO 2. Fe and Co doped Mn-Ce/TiO 2 catalysts for low temperature NH 3 -SCR with SO 2 resistance were investigated via in-situ DRIFTS, SO 2 -TPD and FTIR. The activity results indicated that Fe and Co co-doped catalyst with an Fe/Co molar ratio of 2:4 (2Fe4Co-MCT) showed excellent SO 2 resistance (98% NO conversion) at 200 °C when compared to the Mn-Ce/TiO 2 catalyst. In-situ DRIFTS and SO 2 -TPD results showed that SO 2 reacted with NH 3 to form (NH 4) 2 SO 4 or NH 4 HSO 4 as reversible deactivation blocking the active sites. Moreover, SO 2 -TPD results further implied that irreversible deactivation of Mn-Ce/TiO 2 occurred by SO 2 due to the formation of thermal stable sulfated species (MnSO 4 , Ce(SO 4) 2 or Ce 2 (SO 4) 3) to reduce active substances. The adsorption characteristics by in-situ DRIFTS revealed that more absorbed SO 3 , surface sulfite/sulfate and bulk-like sulfate species were formed on Mn-Ce/TiO 2 catalyst, while Fe and Co addition to Mn-Ce/TiO 2 significantly decreased the sulfur adsorption. The uniform distribution of Fe and Co on the Mn-Ce/TiO 2 surface stopped SO 2 diffusing to the inner layer of catalyst. In-situ DRIFTS also illustrated that the SCR reaction over 2Fe4Co-MCT catalysts mainly followed by Eley–Rideal (E–R) mechanism in the presence of SO 2 , which the adsorbed NH 3 and NH 4 + species reacted with gaseous NO species to produce unstable NH 4 NO 2 and then rapidly decomposed into N 2 and H 2 O. [ABSTRACT FROM AUTHOR]

Highlights • A MnCe/Ti catalyst with good oxidation performance for NO and SO 2 was prepared. • A NTP catalytic oxidation system was constructed to simultaneously remove NO and SO 2. • Highest NO and SO 2 removal efficiencies (86.9% and 100%) were achieved. • Removal efficiency and interactions between NO and SO 2 were analyzed. • The novel reactor enhanced the removal efficiency and reduced the energy consumption. Abstract In this paper, non-thermal plasma (NTP) discharge and catalyst were integrated, and the dielectric barrier discharge (DBD) reactor was used to prepare a MnCe/Ti catalyst. We then measured its surface characteristics. A NTP catalytic oxidation experimental system based on the MnCe/Ti catalyst was constructed for simultaneous desulfurization and denitrification, and the efficiency of the system for the simultaneous removal of NO and SO 2 in simulated flue gas was verified. The effects of specific energy density (SED), flue gas flow rate, and the initial concentrations of NO and SO 2 on the removal efficiencies as well as the interactions between NO and SO 2 were analyzed. The NO and SO 2 removal efficiencies and the corresponding energy efficiency of the integrated system were compared to the system using only the DBD reactor. The results showed that the MnCe/Ti catalyst exhibited higher dispersion of metal oxide active components on the surface and had a higher content of catalytic oxidation active substances than non-doped Mn/Ti and Ce/Ti catalysts. With a SED in the range of 30–250 J/L, the NO and SO 2 removal efficiencies increased as the SED increased. At low initial concentrations (200 mg/m3 NO and 1000 mg/m3 SO 2), the highest NO and SO 2 removal efficiencies (86.9% and 100%) were achieved. Versus the flue gas treatment system using only the DBD reactor, the system using the MnCe/Ti catalyst-filled DBD reactor simultaneously removed NO and SO 2 with enhanced efficiencies and reduced system energy consumption—this is a reference for further optimization of the flue gas treatment system using a DBD-wet electrostatic precipitator (WESP). [ABSTRACT FROM AUTHOR]

Abstract Alkaline injection is an effective way to control the emission of high concentration SO 3 caused by the use of high-sulfur coal and selective catalytic reduction (SCR), but its performance is affected by the competitive absorption of SO 2. A fixed-bed reactor was used to study the competitive absorption of SO 3 and SO 2 by Ca(OH) 2. The dynamic absorption curves in different atmospheres were obtained, the intermediate products were characterized, and the competitive absorption mechanism was discussed. The absorption of SO 3 and SO 2 consists of the chemical kinetics-controlled and product layer diffusion-controlled stages. In the chemical kinetics-controlled stage, the SO 3 and SO 2 removal efficiencies were around 90% and 55% at first and then decreased; the SO 3 selectivity was around 0.1 at first and then increased. In the product layer diffusion-controlled stage, the SO 3 removal efficiency gradually decreased but kept greater than 10%, while the SO 2 removal efficiency deceased to zero; the SO 3 selectivity continued to increase and reached 0.31 at most when SO 2 absorption ceased. There existed significant competition between SO 3 and SO 2 absorption. The increasing SO 3 concentration promoted the SO 3 absorption and the increasing SO 2 concentration decreased it. The absorption of SO 3 increased the intensity of the SO 4 2 - band, decrease the intensity of the SO 3 2 - band, and made the product layer more compact. The possibility of SO 3 reacting with the components (CaSO 3 , CaSO 4 and CaCO 3) on the reacted Ca(OH) 2 surface was analyzed. Ionic diffusion was proposed as the main mechanism of the continuous SO 3 absorption after the formation of a dense product layer. [ABSTRACT FROM AUTHOR]

Highlights • Pressurized oxy-combustion experiments with continuous coal-feeding were conducted. • Simultaneously low CO, NO x & SO 2 emission observed during high pressure combustion. • Low UBC and CO emission demonstrated the high combustion efficiency in POFBC. • NO and SO 2 emission had a sharp drop while N 2 O increase slightly in oxy-combustion. Abstract Pressurized oxy-fuel combustion is a promising technology for CO 2 capture with respect to its high combustion efficiency and the simultaneous reduction of gaseous pollutants. A 10 kW th bubbling fluidized bed reactor with continuous coal-feeding was designed, and effects of pressure, temperature and fuel types on pollutant emission were investigated in detail. Generally, the relatively low carbon content in the ash and CO concentration in the flue gas demonstrated that the combustion efficiency was improved by high pressure. The concentration of NO, N 2 O and SO 2 showed decreasing trends with the increase of pressure. Moreover, the effect of pressure on the emission of NO and SO 2 in the lower pressure (≤0.3 MPa) was more pronounced than that in the higher pressure. The concentrations of NO and SO 2 correlated positively with temperature, while for N 2 O, it had a negative correlation. Compared with air combustion, NO and SO 2 emission dropped sharply in 21%O 2 /79%CO 2 atmosphere. However, N 2 O concentration during oxy-combustion was slightly higher than that in air combustion in the range of experimental pressure. [ABSTRACT FROM AUTHOR]

The O 3 /H 2 O 2 advanced oxidation process (AOP) was, for the first time, utilized for low-temperature NO X removal. The present method has a high NO X removal, which is 58% higher than the sum of that for single O 3 and H 2 O 2 method with O 3 /NO molar ratio of 0.5. Besides, much O 3 consumption, together with operating costs will be saved. The improved activity in O 3 /H 2 O 2 is due to the increased generation amount of OH and O 2 − /HO 2 radicals than the consumption amount of O 3 when the molar ratio of O 3 /NO < 1, and the O 2 − /HO 2 radical can selectively oxidize NO into HNO 3 with a fast rate constant in a single step, while OH can non-selectively oxidize NO and NO 2 also at a fast rate constant. The SO 2 in the flue gas even poses a positive effect on the NO X removal. Absorption by NaOH solution is generally followed by the O 3 /H 2 O 2 method, resulting in the final 95% NO X removal with the O 3 /NO molar ratio of 0.5. Only NO 3 − ions can be detected as the liquid production through ion chromatography for the O 3 /H 2 O 2 method. We expect that this study can shed some lights on the route design for simultaneous NO X and SO 2 removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 3 and Hg0 can be synergistically oxidized by Cu 3 -ATP under sufficient reaction time despite competition exists. • Cu 3 -ATP shows good sulfur resistance in Hg0 oxidation as HCl presents, but SO 2 partially inhibits NH 3 oxidation. • SO 2 interrupts NH 2 → NO x conversion in iSCR mechanism for NH 3 oxidation. • Surface active Cl for Hg0 oxidation has higher activity when SO 2 is present. NH 3 and Hg0 could be synergistically oxidized by copper modified attapulgite (Cu 3 -ATP) catalyst at the gas hourly space velocity (GHSV) below 5 × 104 h−1 despite competition exist between these two reactions. Its Hg0 oxidation showed good sulfur resistance when HCl was present, but the NH 3 oxidation was partially inhibited after SO 2 was added. In order to explain this phenomenon, the composition and physical characteristics of Cu 3 -ATP before and after sulfurization were characterized by XRF, BET, XRD and FTIR. And H 2 -TPR, NH 3 -TPD, in situ DRIFT and XPS of the catalysts were adopted to reveal the influence of SO 2 on NH 3 /Hg0 oxidation and the reaction mechanisms. The results showed that SO 2 would adsorb and oxidize on the catalyst surface to form very small amount of sulfite and sulfate species, and partially change the composition and structure of Cu 3 -ATP. This reduced the reducibility of Cu 3 -ATP and increased the weak and moderate acid sites on its surface. The presence of SO 2 was beneficial to NH 3 adsorption, but inhibited NH 2 → NO x conversion in iSCR mechanism for NH 3 oxidation. Cl 2 formation were also inhibited by SO 2 , while the generated surface active Cl and O species could ensure high Hg0 oxidation efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • HCl and SO 2 removal by alkaline and mechanical modified fly ash were studied. • SO 2 removal efficiency can reach 100% and that of HCl can maintain above 90% • Mechanical modification process increases the specific surface area of fly ash. • Ball milling process makes NaOH adhere uniformly in an amorphous structure. • Fly ash collection-online modification-timely injection was proposed for application. In this study, fly ash was modified by ball milling through coupling alkaline and mechanical to achieve the reuse of fly ash. The adsorption capacity of fly ash for acidic gases was improved in experiments using simple ball milling. Under the optimal ball milling conditions with coupled NaOH, the desulfurization efficiency can reach 100% and the dechlorination efficiency can be maintained above 90% for the first 100 s of the experiment. Different characterizations show that the ball milling process increases the specific surface area of fly ash, which makes NaOH adhere uniformly to the surface of fly ash particles in an amorphous structure and improves the adsorption effect of the fly ash on acid gases. In addition, experiments with different gas parameters proved that increased temperature, increase of the flue gas flow rate, and increase of the acidic gas concentration in flue gas all lead to the decrease of the modified fly ash's deacidification efficiency. This provides a reference for engineering applications of modified fly ash under different working conditions. In summary, a comprehensive technical route of "fly ash collection - online modification - timely injection" is proposed in the municipal solid waste incineration (MSWI) plant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfate increased the adsorption of NH 3 , but the increased NH 3 was not active. • Mo doping could inhibit the sulfation of the catalyst. • Mo doping could alleviate the competitive adsorption among NO x , H 2 O and SO 2. • Mo doping changed the reaction mechanism of CeO 2 -Nb 2 O 5 /TiO 2 catalyst. MoO 3 -doped CeO 2 -Nb 2 O 5 /TiO 2 catalyst was synthesized by a sol–gel method. It was found that Mo doping observably enhanced the tolerance of CeO 2 -Nb 2 O 5 /TiO 2 catalyst to the combined poisoning of H 2 O, SO 2 and K 2 O. Mo doping could restrain the generation of ammonium sulfate and metal sulfate on the surface of the catalyst. This came down to the large specific surface area, strong acidity and superior redox performance of CeO 2 -MoO 3 -Nb 2 O 5 /TiO 2 catalyst. In situ DRIFTS results indicated that K/S/H-CMNT catalyst still proceeded the SCR reaction according to the L-H and E-R mechanisms together, while K/S/H-CNT catalyst only followed the E-R mechanism. Mo doping could enhance the adsorption of NH 3 and NO x species in the presence of K 2 O, H 2 O, and SO 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ce-OMS-2 is successfully synthesized to promote the NH 3 -SCR performance and enhance the anti-SO 2 ability at low temperatures. • Maintaining the Ce-OMS-2 structure with polyvalent manganese species and active oxygen species is important to SCR activity. • The charge transfer between Mn and Ce via the Ce-O-Mn bond is found to be the key factor for realizing good SO 2 tolerance. • The number of Brønsted acid sites in Ce-OMS-2 can also favor SO 2 resistance. Mn-based catalysts for the low-temperature selective catalytic reduction (SCR) of NO x by NH 3 can be strongly deactivated due to the generation of MnSO 4 derived from upstream SO 2 and H 2 O. In this study, a catalyst architecture based on a Ce-doped manganese oxide octahedral molecular sieve (Ce-OMS-2) was successfully synthesized to promote NH 3 -SCR activity and enhance SO 2 tolerance at low temperatures. We investigated the role of Ce and its specific octahedral molecular sieve structure on the anti-SO 2 poisoning effect of Ce-OMS-2. Maintaining the manganese oxide octahedral molecular sieve structure with polyvalent manganese species and active oxygen species and the charge transfer between Mn and Ce via the Ce-O-Mn bond in the Ce-OMS-2 catalyst are found to be the key factors for the realization of excellent NH 3 -SCR activity and SO 2 tolerance. In-depth in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) show that the number of Brønsted acid sites in Ce-OMS-2 can also favor SO 2 resistance. This study provides new insight into the mechanism for de-NO x activity and SO 2 tolerance on Ce-OMS-2 catalyst and is beneficial for the design of anti-SO 2 NH 3 -SCR catalysts. [ABSTRACT FROM AUTHOR]

• The connection between the mechanism model and the single-layer gated neural network model was analyzed. • This paper proposed a new deep learning model for predicting SO 2 concentration in CFB units. • The validity and superiority of the model are verified through ablation experiments and comparative experiments. Pollutant prediction for coal-fired circulating fluidized bed units is crucial for ultra-low emission optimization. Accurate prediction models can assist in the control optimization of the unit. Mechanism models are limited by the determination of parameters, coefficients, and fitting functions in the model and require a large amount of operational and unit design data in practical applications. With the development of deep learning, more and more deep learning models are used in parameter prediction. These models suffer from insufficient prediction accuracy when performing parameter prediction tasks due to the lack of a priori knowledge of the mechanism process. This paper analyzed the relationship between the differential equation model under the first-order Taylor expansion and the single-layer Gated Recurrent Unit neural network model. According to the analysis results, this paper proposed a mixed prediction model of SO 2 concentration. The ablation study demonstrated the validity of the predictive model structure. The operation datasets of two actual units were used for verification. In terms of MAE indicators, the results of the proposed model on the two data sets are 124.5669 mg/Nm3 and 178.0473 mg/Nm3. In terms of MAPE indicators, the results of the proposed model on the two data sets are 5.85% and 14.07%. [ABSTRACT FROM AUTHOR]

CuO loaded MnO x /TiO 2 mixed oxide (CuMnTi) synthesized by an ultrasonic-assisted impregnation method was for the first time employed for simultaneous nitrogen monoxide (NO) reduction and elemental mercury (Hg 0 ) oxidation under selective catalytic reduction (SCR) atmosphere with the presence of NH 3 . The CuMnTi catalyst exhibited a wide temperature window from 150 to 250 °C for both NO reduction and Hg 0 oxidation. At the optimal temperature of 175 °C, CuMnTi reduced 96.4% of the inlet NO and oxidized 100% of the inlet Hg 0 at a very high gas hourly space velocity (GHSV) of 40,000 h −1 . O 2 , HCl and NO significantly promoted Hg 0 oxidation and offset the adverse effect of detrimental flue gas components such as water vapor, SO 2 and NH 3 . The protection effect of CuO over MnO x reserved enough active sites of CuMnTi for Hg 0 oxidation in the presence of NH 3 or SO 2 . Compared with MnO x /TiO 2 (MnTi), the superior redox property, enlarged Hg 0 adsorption capacity and decent SO 2 resistance of CuMnTi ternary system were evidenced to account for its improved catalytic activity. This study indicated future potential for applying CuMnTi catalyst in simultaneous NO reduction and Hg 0 oxidation in low-temperature (150–250 °C) and low-rank (sub-bituminous and lignite) coal combustion flue gases. [ABSTRACT FROM AUTHOR]

This paper developed an integrated system of Dielectric Barrier Discharge (DBD) with Wet Electrostatic Precipitator (WESP) for simultaneous removal of NO and SO 2 . In view of practical application, the effects of some key factors such as peak-peak voltage (V p-p ), O 2 and H 2 O contents on the simultaneous removal of NO and SO 2 were systematically investigated. The results indicated that, in single DBD process, the additions of O 2 and H 2 O significantly promoted the removal of SO 2 , especially in presence of V p-p , but remarkably inhibited the conversion of NO, which was due to the regeneration of NO from the radical-induced reactions among N , O and OH . WESP played a key role in capturing the oxidizing products and acid aerosols, and as anticipated, the integrated system of DBD-WESP showed a better performance on the simultaneous removal of NO and SO 2 , with the best efficiencies of 98.9% for SO 2 and 87.1% for NO. The interaction mechanism among the components in the presence of V p-p was speculated, the transformations of SO 2 and NO in this system were also proposed. The removal products of SO 2 and NO by the integrated system were determined as sulfate and nitrate according to the Ion Chromatography (IC) analysis of the spent solution collected in WESP. [ABSTRACT FROM AUTHOR]

Here we systemically elucidated the compositions and distributions of polluting materials during sludge combustion using both experimental and theoretical methods where the roles of ash were clarified in a category within aluminosilicate system. With regard to the polluting gases, an increasing temperature increased the SO 2 release in replace of SO 3 and sulfates while continuously enhanced the formation of NO and NO 2 . Comparatively, an increasing input oxygen amount had limited effect on S-bearing gases whilst continuously increased the NO x release. Additionally, the ash had a sulfur fixation effect through inducing the transformation from oxides to sulfates. The trace elements were overall categorized into four types based on their volatilities and the distributions and mineral phases of them were then clarified in detail. It was proved that with increasing temperature, they were increasingly distributed in gaseous state with ash providing a fixation effect. Moreover, 5 kinds of decomposition reactions related to polluting materials, namely sulfates, oxides, arsenates, silicates and hydroxides, were deeply analyzed from a respect of Gibbs energy where their stabilities and roles of ash were identified. Furthermore, the sludge combustion was experimentally clarified using a TG-MS system and here we defined a new parameter, namely peak index, to characterize the releases of polluting gases. This not only deepened the understanding of sludge combustion experimentally but also partially validated the theoretical analysis in quantity. Most importantly, the present study contributed to establishing a foundation for controlling and mitigating the environmental impacts of polluting materials toward efficient and clean sludge combustions. [ABSTRACT FROM AUTHOR]

This paper developed an integrated dual-reactor system for simultaneous removal of SO 2 and NO, in which, the first reactor is mainly used to oxidize NO by NaClO 2 , and the second reactor is used to deeply removal of SO 2 , NO, NO 2 and absorb the acidic ClO 2 released from the first reactor by sodium humate (HA-Na). This novel system exhibits some superiorities, including the reagents dosages very low, the lower emitted concentrations of SO 2 and NO x than the ultra-low emission standards, the mild applied conditions of pH and temperature in view of practical application. The best concentrations of NaClO 2 and HA-Na were determined as 0.03%wt and 1.0%wt. The appropriate pH ranges were selected as 3–7 for NaClO 2 and 11–12 for HA-Na. The variation of temperatures of the dual reactors exhibited a slight effect on the yield of NO 2 . The presence of CO 2 produced a remarkable inhibition on the removal of SO 2 and NO x . The addition of HCO 3 − in NaClO 2 significantly decreased the removal efficiency of NO as well as the yield of NO 2 . The existence of HCO 3 − in HA-Na accelerated the release of NO 2 . The removal products of SO 2 and NO in the dual-reactor system were determined as Na 2 SO 4 and NaNO 3 by XRD, XPS and EDS. The reaction mechanism for simultaneous removal of SO 2 and NO was speculated. Finally, the application prospect of this novel system was initially analyzed. [ABSTRACT FROM AUTHOR]

The objective of this work was to find the optimal preparation methods of semi-coke and investigate the absorption mechanisms in the removals of SO 2 and NO x . Semi-cokes, treated by different combined activation methods, were used to remove SO 2 and NO from simulated flue gas in a fixed bed. Detailed characterizations were discussed by BET, SEM and FTIR. Results showed the activated and loaded semi-cokes had better pore structures with more micropores and mesopores. Activated semi-coke had more reactive oxygen groups, including quinines and conjugated ketones while loaded oxides covered some active sites. The physical and chemical properties both acted in the desulfurization and denitration process. Physisorption dominates over chemisorption at low temperatures in the SO 2 removal. The loaded metallic oxides provided some alkaline groups to transport and store products to recover the active sites in the NO removal. C–O–C in ethers and C O in quinones are main active sites for chemically absorbed SO 2 while C–O in primary C–OH and C O vibration in aliphatic groups are two sites for oxidizing NO. Competitive removal greatly improved the desulfurization capacity and slowed down the denitration process due to the occupation of active sites by SO 2 . Also, the generated sulfates leaded to the denitration deactivation while proper oxynitrides and nitrates promoted the absorption and oxidation of SO 2 . [ABSTRACT FROM AUTHOR]

Acidic gas capture by traditional aqueous amine solution requires a plenty of energy for solvent regeneration. A phase-change capture system was considered to be a promising alternative because only the CO 2 -rich phase needs to be recovered and the CO 2 -lean phase can be reused directly without disposal, improving the energy utilization efficiency. Based on this principle, the phase-change absorption behavior of linear polyamines including ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, and cyclic diamines including piperazine (PZ) and triethylene diamine (DABCO) in organic solvents was investigated in the present work. The result indicated that polyamines could react with CO 2 to form carbamate precipitates except DABCO, which had no absorption effect. For the absorption of SO 2 , polyamines could react with SO 2 and water from air to form rare organic sulfites except DABCO, which merely absorbed two SO 2 molecules to form the electron transfer complex DABCO·(SO 2 ) 2 . The peculiar absorption behavior of DABCO for CO 2 and SO 2 implied that it is a highly selective phase-change desulfurizer for flue gas. The sequence of decomposition temperature for the CO 2 capture product was DETA-carbamate > EDA-carbamate > PZ-carbamate, while for the SO 2 capture product was [EDAH 2 ][SO 3 ] > [PZH 2 ][SO 3 ]·H 2 O > DABCO·(SO 2 ) 2 . [ABSTRACT FROM AUTHOR]

A series of novel binary CuCo-SAPO-34 catalyst were developed and applied for selective catalytic reduction of nitrogen oxides from diesel emission exhaust and showed enhanced denitration performance, hydrothermal stability and SO 2 tolerance. [Display omitted] • A novel binary CuCo-SAPO-34 deNO x catalyst was designed and prepared. • CuCo-SAPO-34 exhibited enhanced high temperature deNO x activity. • CuCo-SAPO-34 exhibited enhanced SO 2 tolerance and superior hydrothermal stability. • The role Co promotion and reaction mechanism was studied in detail. It is well known that Cu-SAPO-34 catalyst has high activity for nitrogen oxides (NO x) abatement from diesel vehicle emission. However, its low sulfur resistance and hydrothermal stability still retard its reality application. Herein, a series of novel binary CuCo-SAPO-34 catalysts were designed and prepared through a simple one-pot method and applied for NO x selective catalytic reduction with ammonia. Compared with Cu-SAPO-34, the binary CuCo-SAPO-34 catalysts exhibited enhanced activity and SO 2 tolerance. To investigate the effects of Co addition and the reaction mechanism, various characterizations including X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) mapping, physical and chemical adsorption, the in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs), etc., were adopted. The results reveal that the Co 3 O 4 nanoclusters existing in CuCo-SAPO-34 could efficiently accelerate the oxidation of NO to NO 2 , and the addition of Co is conducive to improving its sulfur resistance. In addition, CuCo-SAPO-34 also displayed superior high- and low-temperature hydrothermal stability. The binary CuCo-SAPO-34 developed in this work may be a good candidate for Cu-SAPO-34 based catalysts in practical diesel vehicle emission control. [ABSTRACT FROM AUTHOR]

[Display omitted] • Regulation of acid-redox properties over FeO x /OAC1.5-60-3 via APS oxygen-functionalization is designed and achieved. • Fe valence and oxygen vacancy in FeO x /OAC1.5-60-3 are tailored based on the metal-support interaction. • Fe dispersion, surface acidity and redox ability of FeO x /OAC1.5-60-3 have remarkably improved. • FeO x /OAC1.5-60-3 shows high LT-SCR activity and resistance to H 2 O and SO 2 poisoning. Carbon-based transition metal catalysts (CTCs) have shown tremendous potential within NO x abatement, while the improvement of low-temperature NH 3 -SCR activity and SO 2 and H 2 O tolerance remains challenging. Herein, we report an easily-achievable strategy to regulate the active phases of the FeO x /AC catalyst via APS oxygen-functionalization for improving in acid and redox properties and facilitating NH 3 -SCR activity. For redox sites, APS oxygen-functionalization boosted the metal-support interaction, immobilized γ-Fe 2 O 3 nanoparticles highly dispersed on FeO x /OAC1.5-60-3 surface. Meanwhile, Fe valence and oxygen vacancy of FeO x were tailored by APS oxygen-functionalization, resulting in the formation of active oxygen vacancy-coupled Fe2+. For acid sites, in situ DRIFTs further confirmed that APS oxygen-functionalization enhanced the adsorption and activation properties of NH 3 over the oxygen-containing functional groups (OCFGs) on FeO x /OAC1.5-60-3. Due to the improvement of acid and redox properties, FeO x /OAC1.5-60-3 delivered superior NO conversion (>90 %) at 120–250 °C and SO 2 /H 2 O resistance in comparison with FeO x /AC. Therefore, this work sheds light on a robust and pragmatic strategy for the rational design of CTCs and provides a new insight in improving catalytic performance of CTCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Demonstrated that it is feasible to utilization of active inherent minerals for high performance AC production. • The combined effect of pyrite and calcite in coal plays a critical role on AC structure development. • CaS was formed during the AC preparation. • Enhancement adsorption of SO 2 and/or NO was achieved due to the combined effect of Ca-Fe. • Related combined impact mechanisms were proposed. Utilization of inherent active minerals in coal is an effective strategy for high-performance activated carbon (AC) production, such as calcite and pyrite. In this research, ACs were prepared through blending demineralized Ningxia coal with calcite (CaCO 3 , 0–8 wt.%) and pyrite (FeS 2 , 0–3 wt.%). The combined effect of inherent pyrite and calcite in coal on the as-prepared AC's texture and SO 2 and/or NO removal performance was discussed. The results indicated that: (1) The combined effect of calcite and pyrite showed nonlinearly on weight loss and burn-off, and reduced AC's yield. The impact of calcite on pore structure was more evident than pyrite. Meanwhile, calcite and pyrite enhance the content of C O (C 1 s) and π-π*, and new mineral CaS could be formed through interaction between calcite and pyrite; (2) Calcite and pyrite promote AC's SO 2 and NO removal ability evidently. Pyrite and calcite regulate physiochemical texture, and the physical and chemical adsorption of SO 2 /O 2 /H 2 O was enhanced. Meanwhile, iron and calcium ingredients in AC catalyzed desulfurization. CaO could participate in the SO 2 removal process. Fe 2 O 3 oxidized SO 2 to SO 3 and then forms H 2 SO 4 rapidly, meanwhile, a redox cycle of Fe3+ and Fe2+ was established. Enhancement of NO removal was more evident than SO 2 , which was mainly due to Fe 2 O 3 being helpful to oxidizing NO to NO 2 , and calcium components could enhance the adsorption of NH 3 and NO and finally promote "fast SCR"; (3) During simultaneous desulphurization and denitrification, sulfur capacity was obviously enhanced and NO conversion was declined. The mechanism was proposed as follows: the existence of NH 3 could enhance the SO 2 adsorption through chemisorption and/or catalytic oxidization; Due to the competitive adsorption of SO 2 , denitrification declined. This research could guide high-performance AC production by utilizing high-inorganic-calcium/iron/sulfur coal. [ABSTRACT FROM AUTHOR]

The release of four sulfur and chlorine species (SO 2 , H 2 S, COS and HCl) from a US-American high sulfur high volatile bituminous coal under pyrolysis and combustion conditions was experimentally investigated in an entrained flow reactor. The reactor design and measuring techniques are presented. Under pyrolysis conditions, the reactor was operated at four wall temperatures (900, 1000, 1100 and 1300 °C). With each reactor temperature increment, the release of sulfur from the coal was increased. Approximately 11% of total coal sulfur volatilized at 1300 °C. Under combustion conditions, the same temperature influence already observed during the pyrolysis experiments applied for sulfur release. Under fuel rich conditions, SO 2 , H 2 S and COS were detected, with hydrogen sulfide being the major contributor. Under exactly stoichiometric and fuel lean conditions, almost all sulfur in the product gas occurred as sulfur dioxide. While at 1000 °C, only 63–78% of coal sulfur was found in the gas phase, all sulfur was released when the reactor temperature was changed to 1300 °C. During pyrolysis, hydrogen chloride concentration reached its final value at 1100 °C. This temperature was sufficient to transform all volatile chlorine, which amounts to 15% of total coal chlorine, to the gas phase. While up to 50% of coal chlorine was released as hydrogen chloride during fuel rich combustion, no HCl was detected under stoichiometric conditions and with excess air. [ABSTRACT FROM AUTHOR]

A novel wet flue gas desulfurization method based on the Bunsen reaction of sulfur-iodine (SI) thermochemical cycle was investigated in this paper. I 2 and HI absorption system was utilized to remove SO 2 from simulated coal-fired flue gas. The SO 2 removal efficiency was about 98.8% when the I 2 concentration was 25.6 mmol/L. The influences of reaction temperature, initial SO 2 concentration and the other flue gas components on SO 2 removal were investigated, respectively. The absorption products were H 2 SO 4 and HI, which could be easily separated by distillation. Compared with the traditional wet flue gas desulfurization (FGD) byproducts, such as gypsum or magnesium sulfate, H 2 SO 4 has better commercial value and application prospect. Moreover, HI could be used as the raw material for the hydrogen production in the SI thermochemical cycle. In short, it is a promising technology for the SO 2 removal and recycling from coal-fired flue gas. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) supported vanadium catalysts were obtained using the wet chemical impregnation method, and their removal of NOx with the presence of SO 2 at low temperature was evaluated. The effect of carbon was observed by comparing different carbon-based catalysts. V 2 O 5 /SiC (1 wt.%) catalyst had a NOx removal efficiency of 86% in the presence of SO 2 at 250 °C with a GHSV of 180,000 h −1 . In this study, the temperature-programmed desorption of NH 3 (NH 3 -TPD) and temperature-programmed decomposition (TPDC) of NH 4 HSO 4 deposited on the catalysts and reaction were performed to determine the influence of carbon on the performance of a carbon-based catalyst in the presence of SO 2 . The NO on the carbon support can effectively react with the NH 4 HSO 4 formed on the catalyst surface at low temperatures. Additionally, the adsorption of NH 3 was higher on carbon-based catalysts that were pre-adsorbed with SO 2 + O 2 . Thus, SO 2 promotes the activity of a carbon-based catalyst at low temperatures, and carbon has very important effect on the promotion of that activity. [ABSTRACT FROM AUTHOR]

This work contrasted gaseous emissions of carbon, sulfur and nitrogen oxides from combustion of several types of biomass including woody, herbaceous and crop-derived wastes, pulverized in the size range of 75–150 μm. Both raw and torrefied biomass were exposed to high heating rates (10 4 –10 5 K/s) in a laboratory-scale electrically-heated drop-tube furnace, operated at 1400 K. Combustion occurred under fuel-lean conditions. Torrefied biomass has lower volatile matter content, higher fixed carbon content and higher heating value than raw biomass. Results revealed that (a) CO 2 emission factors from torrefied biomass were higher than those from raw biomass, reflecting the higher carbon content of the former, however there was no uniform trend in emission factors (kg/GJ); (b) SO 2 emission factors of torrefied biomass were lower than those from raw biomass, even if some torrefied biomass types contained higher sulfur mass fractions than their raw biomass precursors. All raw and torrefied biomass, with one exemption, generated lower SO 2 emission factors than a typical sub-bituminous coal; (c) torrefied biomass has higher fuel-nitrogen mass fractions than their raw biomass precursors; however, there was no clear trend in NO x emission factors between raw and torrefied biomass, as torrefied herbaceous and woody biomass types generated higher while torrefied crop biomass types generated lower emission factors than their raw biomass precursors. Comparing with the sub-bituminous coal, some raw and torrefied biomass types generated lower and some higher NO x emission factors. Overall, combustion of most types of biomass, either in raw or torrefied state, can result in lower SO 2 and NO x emissions factors than those of typical western US sub-bituminous coals while, in principle, generating minimal net emissions of carbon. [ABSTRACT FROM AUTHOR]

[Display omitted] • A direct redox reaction was constructed between NO and SO2 for simultaneous removal. • The strategy minimized usage of other reductants/oxidants and reduced secondary pollution. • A unique SO2 adsorption route, SO2 disproportionation was triggered at La sites. • Oxidation state of Co had a critical effect on SO2 adsorption route and DeNO x activity. A novel simultaneous removal strategy for NO and SO 2 was proposed to meet the increasingly strict emission requirements, i.e. triggering the direct redox reaction between two pollutants (SO 2 + NO + O2− = SO 4 2− + 1/2N 2), which chemically couples SO x and NO x removal and prevents the possible competition between DeNO x and DeSO x reactions. In this fundamental study, we tailor-made an efficient Pd-La 1.5 Co 0.5 O 3 catalyst that accelerated the designed reaction to an industrially applicable level, achieving a prominent SO 2 adsorption capacity of 2465.2 μmol g−1 and NO reduction capacity of 1891.3 μmol g−1 over 60 min when SO 2 and NO are simultaneously fed at 680 °C. Over this catalyst, SO 2 adsorbed on the La site underwent disproportionation via sulfite intermediate into oxysulfate and sulfide, which gave access to NO reduction. Co in the catalyst played a complex role. The active oxygen species binding to Co3+ in perovskite competed with NO in SO 2 oxidation. However, this generated Co2+ that was found to take part in sulfite disproportionation through forming Co 9 S 8 , which accelerated the disproportionation and NO reduction. The catalyst is promising to be industrially applied as an additive of the FCC catalyst or flue gas aftertreatment catalyst and exhibited 45 % higher DeNO x efficiency and 28 % higher DeSO x efficiency in a simulated catalytic cracking/coke combustion cycle than the commercial additives. The findings open a new avenue for the development of novel environmentally benign and cost-effective simultaneous removal technology. [ABSTRACT FROM AUTHOR]

• SO 2 resistance of adsorbents could be largely improved by increasing active center. • Co 3 O 4 /AC showed higher SO 2 affinity and lower mercury removal ability than CeO 2 /AC. • 20%CeO 2 /AC showed good mercury removal ability, SO 2 resistance and reuse ability. How to enhance the SO 2 tolerance of transition metal oxide-supported activated carbon is one of the hottest issues in the field of mercury capture from flue gas. Addition of a foreign metal ion to prepare bimetallic adsorbent is a common method of improving the SO 2 tolerance of adsorbent. However, this approach suffers from high cost and a complex preparation process. In this study, CeO 2 - and Co 3 O 4 -supported activated carbon (m %CeO 2 /AC and m %Co 3 O 4 /AC), with various loading values of active center, were prepared by an incipient wetness impregnation method, and their SO 2 tolerances were compared. The mercury removal performance and SO 2 tolerance of both CeO 2 /AC and Co 3 O 4 /AC could be remarkably improved through increasing the loading amount of the active center. Co 3 O 4 /AC exhibited high affinity with SO 2 , and the chemisorbed oxygen in Co 3 O 4 would be largely consumed, when SO 2 was present in the flue gas, resulting in a significant decrease of mercury removal efficiency. The mercury removal efficiencies of 20%CeO 2 /AC, 40%CeO 2 /AC and 60%CeO 2 /AC were 86.1%, 93.7% and 93.7%, respectively, during removal of mercury from flue gas at 150 °C in the presence of SO 2. 20%CeO 2 /AC was the optimal adsorbent for mercury capture from flue gas, owing to its excellent mercury removal efficiency, strong SO 2 tolerance and relatively lower cost. The mercury species formed over spent 20%CeO 2 /AC were HgO and HgSO 4. The HgO was generated through the reaction of mercury and chemisorbed oxygen, while the formation of HgSO 4 was due to the reaction between mercury, SO 2 and chemisorbed oxygen. The regeneration investigation indicated that the activity of spent 20%CeO 2 /AC could be almost fully recovered through a temperature-programmed decomposition and desorption process. The present study showed that the SO 2 tolerance of CeO 2 /AC could be easily improved through regulation of the loading amount of the active center. [ABSTRACT FROM AUTHOR]

• Multi-stage fluidized bed (MSFB) is explored for the purification of flue gas. • MnO 2 is used as the active medium in MSFB to simultaneously remove NO and SO 2. • 100% removal efficiency of both NO and SO 2 is achieved in the four-stage MSFB. • The MSFB system can run stably in the presence of 10 vol% H 2 O steam below 200 °C. • The MnO 2 is converted to MnSO 4 which can be easily regenerated by ammonia water. To overcome the easy poisoning and deactivation of denitrification catalysts by SO 2 at low temperatures, the bench-scale multi-stage fluidized bed (MSFB) process with the active MnO 2 medium (feeding rate of 0.3–1.2 kg/h) is designed and applied to simultaneously remove the NO and SO 2 from flue gas of medium/small industrial boilers in the low-temperature range of 100 – 200 °C, which demonstrates excellent and stable removal efficiency of both NO and SO 2 even in the presence of 10 vol% water. In the MSFB system, the fluidized MnO 2 particles in different layers flow against the simulated flue gas stage by stage, and the deactivated MnO 2 will be continuously discharged and replaced with fresh MnO 2 to keep the system effective and steady. The MnO 2 medium acts as both denitrification (DeNO x) catalyst and desulfurizer, and the limited backmixing and layered arrangement of the MSFB system ensure the high removal capacity and sufficient utilization of MnO 2 material. The multiple structural characterizations further reveal that the active MnO 2 is gradually consumed by SO 2 to form MnSO 4 stage by stage with decreased specific surface and pore volume, accounting for its gradually decreased removal efficiency of both NO and SO 2 stage by stage. And the deactivated MnO 2 can be easily regenerated by aqueous ammonia with the conversion of MnSO 4 to active MnO 2. The demonstrated advantages of the MSFB system with MnO 2 will provide a promising technical route for the simultaneous removal of NO and SO 2 from low-temperature flue gas in industry. [ABSTRACT FROM AUTHOR]

• Interaction between the sewage sludge and coal slime during their co-combustion was found. • SO 2 formation and release mechanism during co-combustion of sewage sludge and coal slime was revealed. • AAEMs play a key role on the evolution of S-functional groups. The production of sewage sludge (SS) and coal slime (CS) is increasing year by year, which affects the ecological environment and human daily life, and it is urgent to deal with them reasonably. This study investigated the SO 2 release characteristics and the evolution of S functional groups and minerals during the combustion of SS, CS and their blends. The results showed that the co-combustion of SS and CS had an interaction on desulfurization. When the temperature was 800 ℃ and the blend ratio of SS was 20%, it was most beneficial to suppress the emission of SO 2. The types of S functional groups in SS and CS were similar but the relative content was different. The evolution of some S functional groups showed various laws. In the early stage of co-combustion, Sulfate (S1) reached maximum value earlier and decreased at the end of co-combustion, and Sulfide (S5) were more likely to be converted to aromatic-S (S4). According to XRD and SEM-EDS results, Ca (mainly CaCO 3) in the fuels had a significant effect on SO 2 release characteristics during the co-combustion. CaO formed by thermal decomposition of CaCO 3 could react with SO 2 to form intermediate solid products (CaS and CaSO 3). These intermediates further reacted with O 2 to generate CaSO 4 , thus retaining SO 2 in the ash. Some CaSO 4 was decomposed in the later stage of combustion, leading the re-release of SO 2. Excessive combustion temperature and reductive gases would lead to the decomposition of CaSO 4 , which reduced the ability of Ca to absorb SO 2. [ABSTRACT FROM AUTHOR]

• Static, segmentation and dynamic models for soft sensing of SO 2 emission were built based on five algorithms. • All the dynamic models perform better than both static models and segmentation models. • Dynamic ANN model gives the highest accuracy for predicting SO 2 concentration. Static models, segmentation models and dynamic models for soft sensing of SO 2 emission were developed based on the Ordinary Least Squares, Support Vector Regression, eXtreme Gradient Boosting, Random Forest and Neural Network algorithms with real operational data from a 1000 MW coal-fired power plant with ultra-low emission systems. The prediction results of test set show that static models are not suitable for modeling the desulfurization systems with complex condition and time-delay process. Thus, segmentation models and dynamic models were used to optimize the prediction accuracy. All the prediction performance of the nonlinear models was improved significantly with dynamic model, while the prediction performance of the linear model was improved with segmentation model. The dynamic Neural Network model with one hidden layer achieves the most accurate regression result (R2 = 70.4 %, RMSE = 1.95 mg/m3, MAE = 1.53 mg/m3). The results show the superiority of the dynamic Neural Network model over the other and the dynamic Support Vector Regression model perform second-best. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnFeO x nanobelts are bimetallically modified with Nb and Nd for the first time. • The MnFeNb 0.2 Nd 0.1 O x achieves an improved NO x conversion and an enhanced tolerance of SO 2. • The rational design of Nb and Nd enhances the adsorption of NH 3 and NO and reduces the adsorption of SO 2. • The de-NO x reaction over MnFeNb 0.2 Nd 0.1 O x follows both E-R and L-H mechanisms. Nitrogen oxide (NO x) is one of the key factors contributing to air pollution, and selective catalytic reduction with ammonia (NH 3 -SCR) is widely used for denitrification (de-NO x). To effectively deal with the NO x pollution, it is urgent to develop efficient catalyst working at below 300 °C with a wide operating temperature window. Herein, a series of ferromanganese oxides (MnFeO x) nanobelts are bimetallically modified with niobium (Nb) and neodymium (Nd) for the first time via electrospinning method. The resultant MnFeNbNdO x catalysts present improved low-temperature de-NO x performance and sulfur dioxide (SO 2) tolerance, particularly MnFeNb 0.2 Nd 0.1 O x who achieves a NO x conversion up to over 90 % during the range of 120–330 °C and an enhanced tolerance of water (H 2 O) and SO 2. Experimental and theoretical calculations confirm that strong adsorption of nitric oxide (NO) and ammonia (NH 3) and weak adsorption of SO 2 with the synergy of Nd, Nb and Mn enable MnFeNb 0.2 Nd 0.1 O x excellent SCR activity and good SO 2 tolerance. In-situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) further reveal that the de-NO x reaction over MnFeNb 0.2 Nd 0.1 O x follows both Eley-Rideal (E-R) and Langmuir-Hinshel-wood (L-H) mechanisms. This study will inspire the further design and study of the synergy of transition metals and rare earth elements for de-NO x. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of novel ternary CeVO 4 modified with different Nb contents catalysts. • >90 % NO conversion in the range of 210–420 °C with 5 %vol·H 2 O over CeNbVO-2. • Enhancing the surface acidity on CeNbVO-2 by adding proper amount of Nb. • Increase in active oxygen species due to formation of CeVO 4 with Nb n+–O2−-Ce n+ bonds. • Good activity assigned to the synergistic effect between acidity and redox property. A series of novel ternary CeVO 4 modified with different Nb contents (CeNbVO) catalysts were synthesized via alkali-assisted hydrothermal method, and applied for selective catalytic reduction (SCR) of NO x with NH 3. The as-prepared CeNbVO catalysts show enhanced NH 3 -SCR performance compared with the CeVO catalyst. Especially, the optimal CeNbVO-2 with appropriate Nb amount displays the superior NH 3 -SCR activity with above 90 % NO conversion in the range of 210–420 °C with 5 %vol·H 2 O and excellent resistance to H 2 O/SO 2. Effects of Nb-modified CeVO 4 to form surface Ce-O-Nb bonds on improving low-temperature NH 3 -SCR activity and resistance to SO 2 & H 2 O were investigated by using various characterization methods, including XRD, Raman spectroscopy, N 2 physical adsorption, TEM, H 2 -TPR, NH 3 -TPD, O 2 -TPD, NO-TPD, XPS, kinetic tests and in-situ DRIFTS. Different phases can be obtained with the different Nb amount doping, leading to different SCR activity. The pure CeVO 4 phase with the short-range ordered Nb n+–O2–-Ce n+ bond is formed by adding a small amount of Nb in CeNbVO-2. The superior catalytic performance of CeNbVO-2 can be ascribed to its improved acidity and suitable oxidation ability, which may counteract the negative effects of nonselective NH 3 oxidation to N 2 O. It is found that the formation of Nb n+–O2–-Ce n+ bonds can significantly increase the surface active oxygen species and oxygen vacancy of the catalyst. Additionally, the NH 3 -SCR reaction mechanism is revealed using in-situ DRIFTS and kinetic studies. [ABSTRACT FROM AUTHOR]

The influence of co-combustion of bituminous coal and pickling sludge on SO 2 , NO x , HF, HCl and PCDD/Fs emissions was studied in a drop tube furnace. To simulate the combustion condition of suspension firing boilers, the experiment was performed at 1100–1400 °C with the share of sludge in the feed ranging from 0 to 10% by weight. The combustion characteristics of coal and of blended fuels were studied by TG analysis. The results showed that the average combustion efficiency of co-combustion of bituminous coal and pickling sludge in the drop tube furnace is larger than 99%. SO 2 , NO x and HCl emissions had an increasing tendency with the temperature rising, but HF emissions were not sensitive to temperature. SO 2 and HF emissions had a rising trend with increasing share of sludge, while NO x and HCl emissions had an opposite trend. No obvious effect of temperature and the share of sludge on the total TEQ of PCDD/Fs was found, and the emissions of the seventeen congeners were basically stable under different experimental conditions. TG results showed that the combustion characteristics of coal and blended fuels were basically the same. XRD results showed that the ash composition changed significantly with the addition of sludge. Compared to the national standard, when co-combusting of bituminous coal and pickling sludge in commercial power plant, desulphurization and denitrification equipment, activated carbon injection and baghouse should be provided. [ABSTRACT FROM AUTHOR]

The formation of polycyclic aromatic hydrocarbons (PAH) and soot from the pyrolysis of ethylene in the presence of different amounts of sulphur dioxide (SO 2 ) and at different reaction temperatures (1075–1475 K) was studied. The sixteen PAH classified by the Environmental Protection Agency (EPA) as priority pollutants were quantified by gas chromatography–mass spectrometry (GC–MS). Soot formed was collected on a filter at the reactor outlet. The concentration of the main gases obtained was also determined. The harmful potential or toxicity of the EPA–PAH, through the B[a]P-eq, has been evaluated together with the yield to EPA–PAH. The main results show that for a low SO 2 concentration (0.3%), the formation of EPA–PAH and toxicity increase, while high concentrations of SO 2 decrease the yield to soot, EPA–PAH and B[a]P-eq concentration. The highest concentration of SO 2 shifts the maximum concentration of EPA–PAH to lower temperatures. [ABSTRACT FROM AUTHOR]

This research examined the reduction of combustion-generated sulfur dioxide and nitrogen oxide emissions from a pulverized high-sulfur bituminous coal by co-firing it with a lignite coal and by substituting air with O 2 /CO 2 gases, of compositions pertinent to dry once through oxy-fuel combustion conditions. Oxygen mole fractions were in the range of 21–30%. The neat bituminous and lignite coals as well as a 50–50 wt% blend thereof were burned in a laboratory-scale electrically-heated drop-tube furnace under fuel-lean conditions. Coal particles were in the size range of 75–90 μm and the furnace was operated at 1400 K. Results showed that the SO 2 emissions from the lignite coal were drastically lower than those from the bituminous coal, whereas the NO x emissions were only mildly lower. Co-firing the high-sulfur bituminous coal and the low-sulfur lignite coal reduced the SO 2 emissions, under both air and oxy-combustion conditions, to values well-below those predicted by linear interpolation of the respective emissions of the two neat coals. This observation, in conjunction with ash analysis shows that the alkali-rich ashes of the lignite coal acted as sulfur sorbents for the copious SO 2 emissions of the bituminous coal. This behavior was contrasted to SO 2 sorption when the bituminous coal was co-injected with calcium- and sodium-based sorbents at analogous alkali to sulfur ratios. Co-firing of the coals reduced the NO x emissions only mildly, whereas the substitution of the background N 2 gas with CO 2 resulted in much more extensive NO x reductions. [ABSTRACT FROM AUTHOR]

• Effect mechanism of SO 2 on Hg removal by CuMn 2 O 4 was studied by experiment and DFT. • The high-temperature inhibitory effect of SO 2 is related to the sorbent sulfation. • SO 2 chemisorption of CuMn 2 O 4 sorbent is attributed to the orbital hybridization. • SO 2 presence increased the activation energy barrier of Hg*-to-HgO conversion. SO 2 is an important acid flue gas component during solid fuel combustion. The effects of SO 2 on the Hg0 removal performance of CuMn 2 O 4 sorbent and its reaction mechanism were investigated by conducting the mercury adsorption experiments and theoretical calculations. The results showed that SO 2 concentration coupling with the high temperature was the predominant factor affecting the Hg0 removal performance of CuMn 2 O 4 sorbent. At a relatively high temperature (≥200 °C), the presence of SO 2 significantly inhibited Hg0 removal by CuMn 2 O 4 sorbent, and the inhibitory effect was significantly enhanced with the increase of temperature. Hg0 removal efficiency decreased from 88.2 % at 200 ℃ to 17.98 % at 350 °C due to the SO 2 sulfation of sorbent surface. Hg0 removal performance of CuMn 2 O 4 sorbent was not sensitive to the variation of SO 2 concentration at the low temperature of 150 °C. DFT calculation results showed that SO 2 is chemically adsorbed on the sorbent surface, and the adsorption energy of the most stable configuration is −111.78 kJ/mol. The chemisorption of SO 2 on the sorbent surface is attributed to the orbital hybridization among Cu, Mn and O atoms. The adsorption energy of Hg0 on the CuMn 2 O 4 surface decreased in the presence of SO 2. The transformation pathway of Hg0 in the presence of SO 2 includes three steps: Hg0 adsorption, O 2 adsorption, and Hg*-to-HgO conversion. The presence of SO 2 increased the activation energy barrier of Hg* oxidation into HgO. [ABSTRACT FROM AUTHOR]

• Effect of Zr, V, Mo and W-doping of K-OMS-2 in soot combustion was elucidated. • Importance of doping via impregnation or coprecipitation was established. • Catalytic performance was evaluated in the presence of NO and SO 2. • Work function was found as a concise descriptor of catalyst behavior. Two series of cryptomelane doped with d0 ions (Zr4+, V5+, Mo6+, W6+) were synthesized by impregnation and coprecipitation methods. The obtained samples were characterized in detail by XRD, RS, TEM/EDX, XRF, XPS, O 2 -TPD and by the work function measurements. Catalytic tests were performed in tight and loose contacts using various reaction mixtures (O 2 , O 2 + NO, O 2 + NO + SO 2). The role of dopants was examined and discussed in terms of their influence on the principal catalysts' functionalities such as catalytic performance, structural and thermal stability and resistance to SO 2. The work function was found to be a prime descriptor used for the explanation of the catalytic performance in soot oxidation, taking into account the nature of dopants, the way they were introduced, and the composition of the reaction mixture. Due to the formation of a hot ring at the catalyst-soot interface, the oxidation of soot and NO are coupled and significantly influenced by the presence of SO 2. It was found that the catalytic activity of the impregnated samples results from the opposite effects of the work function on soot combustion in NO and on sulfur poisoning of the beneficial NO to NO 2 oxidation. It leads to an optimal work function value of 4.04 eV observed for the W-doped catalyst. For the coprecipitated samples, due to the non-monotonous and opposite character of those processes, the effect of doping on the cryptomelane catalytic performance in the presence of SO 2 is smeared out. [ABSTRACT FROM AUTHOR]

• PAC has two active components of FeS 2 and Fe 7 S 8. • Propose a new catalyst reaction mechanism. • Fe 7 S 8 is the intermediate phase of FeS 2 involved in the reaction path. • Opened up a new technology and field of ore resource utilization. In this study, an iron sulfide catalyst (PAC) was prepared to catalyze the reaction of CO reducing SO 2 to sulfur to satisfy the high activity and stability of the catalyst, simplify the preparation process, and remove the sulfurization process. The physicochemical properties, reduction activity of the iron sulfide catalyst, and reaction mechanism of PAC-catalyzed CO reduction of SO 2 were then systematically investigated. The results indicated that the optimum reaction conditions were a FeS 2 proportion of 6 wt%, a reaction temperature of 550 °C, an airspeed of 5000 h−1, and a CO/SO 2 molar ratio of 2.6:1. Under these conditions, the SO 2 conversion of PAC was stabilized at over 99.5% with a sulfur yield of up to 95.5% within 850 min without deactivating the active component or deteriorating the sulfate. This proves that PAC has very high catalytic activity and stability. The XRD and in situ XRD characterization showed that the reduced PAC contained primarily Fe 7 S 8 in the sulfur phase, while no sulfate and sulfite were found. The reaction mechanism of the PAC-catalyzed CO reduction of SO 2 can be divided into the FeS 2 thermal decomposition mechanism and the COS intermediate product mechanism. [ABSTRACT FROM AUTHOR]

• A novel capture and utilization process for NO x , SO x , and CO 2 is proposed. • The process utilizes metal ion in desalination wastewater. • Using the Ca(OH) 2 for desulfurization, the additional CO 2 emission is prevented. • NO x can be utilized as Ca(NO 3) 2 using Ca(OH) 2 as a reactant. • Using the desalination wastewater, all of the absorbent complete can be substituted. Numerous industries are facing serious environmental contamination, because of the significant emission of nitrogen oxide (NO x), sulfur dioxides (SO 2), and carbon dioxide (CO 2) and it has become imperative to reduce these gaseous emissions. To reduce pollution caused by gaseous emissions, desalination wastewater is possible to be used because it contains highly concentrated useful mineral ions such as Ca2+, Mg2+, and Na+ which react with carbonate, nitrogen, and sulfate ions. This work designed and integrated NO x , SO 2 , and CO 2 capture and utilization processes using desalination wastewater for cleaner production. To design and integrate the NO x , SO 2 , and CO 2 capture and utilization process, a process model is developed based on validated experimental data. The proposed process model comprises the following three steps: (1) electrolysis and metal ion separation of desalination wastewater to produce NaOH, Mg(OH) 2 , and Ca(OH) 2 ; (2) NO x and SO 2 capture and utilization via Ca(OH) 2 ; (3) CO 2 capture and utilization using NaOH, Mg(OH) 2 and Ca(OH) 2. Then the economic feasibility of the suggested process is demonstrated compared to conventional process by economic assessment. As a result, the NO x and SO 2 are captured and utilized at about 90% and 99% respectively. In addition, the CO 2 is captured at about 91% and the conversion yields of each carbonate are 99% and 63% respectively. To demonstrate the economic feasibility of the proposed process, two cases are set. Case 1 is the case that employs selective catalytic reduction (SCR), wet flue gas desulfurization (WFGD), and a CO 2 capture process that uses amine as a CO 2 absorbent with an electrodialysis reclaiming unit. Case 2 is the case that employs SCR, WFGD, and the CO 2 capture process that uses amines with an ion-exchange resin reclaiming unit. As a result, the total annualized cost of the proposed process was ∼7.9% and 14% lower than those of Case 1 and Case 2, respectively. [ABSTRACT FROM AUTHOR]