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The additive effect of different transition metal oxide M' (M' = Fe2O3, MnO2, and WO3) doping on V2O5/ZrO2–CeO2 (V/ZrCe) catalyst with reduced vanadium for simultaneous removal of NO and Hg0 was investigated. V/ZrCe doped with Fe2O3, MnO2, and WO3 and reduced vanadium were prepared by a wet-impregnation method and tested for their catalytic activity of simultaneous removal of NO and Hg0 in the temperature range of 100–400 °C. A combination of various analytical techniques including SEM, BET, XRD, H2-TPR and XPS were used to characterize the characteristics of catalysts. Results indicated that the introduction of M' could enhance the catalytic properties of the catalysts. V0.01Mn/ZrCe and V0.01Fe/ZrCe catalyst presented higher activities than the V0.03/ZrCe catalyst below 250 °C, while V0.01W/ZrCe catalyst exhibited a higher performance in the temperature range of 300–400 °C. The transition metal oxide M' species exist in a well dispersed state on V0.01/ZrCe catalysts. Doping the transition metal oxide M' on V0.01/ZrCe could affect the oxidation state of vanadium oxide and cerium oxide via the reaction of V4++Ce4+↔V5++Ce3+. Besides, the NO conversion was little impacted by Hg0, whereas SCR atmosphere has inhibited on Hg0 oxidation due to the strong competitive adsorption of NH3 with Hg0. The water and sulfur resistance performance decreased in the order of V0.01W/ZrCe> V0.01Fe/ZrCe > V0.01Mn/ZrCe.

To provide insight into optimizing flue gas treatment, the reaction mechanism for simultaneous oxidation of NO and toluene with H2O using a A-site substituted La1-xCoxFeO3 (x=0-0.4) catalysts with three-dimensional porous structure was investigated. The results demonstrated that the partial substitution of La in porous LaFeO3 by Co can induce the structural distortion, promote the specific surface area, enhance more active site exposure and produce abundant reactive oxygen species, including lattice oxygen with higher mobility, more surface adsorbed oxygen as well as oxygen vacancies, which improved the catalytic activities remarkably. Besides, NO and toluene have mutual promoted effects in the reaction system. The inhibition effect of H2O on simultaneous oxidation of NO and toluene was confirmed in that H2O consumes the chemisorbed active oxygen atoms. Without H2O, absorbed NO reacts with chemisorbed oxygen to form NO2, and absorbed toluene is oxidized by lattice oxygen to generate intermediate species which finally completely oxidized into CO2 and H2O. With H2O, H2O react with chemisorbed oxygen to produce -OH species that occupied active sites for toluene adsorption. NO interacts with -OH species to form stable nitrate species, which offsets the inhibitive effect of H2O on NO oxidation due to the consumption of chemisorbed oxygen.

MnxCoy/Zrz-AC prepared by impregnation method was investigated on the simultaneous removal of HCHO and Hg0. The samples were characterized by BET, SEM, XRD, H2 pulse chemisorption, H2-TPR, XPS, Hg-TPD and in-situ DRIFTS. Thereinto, the optimal Mn2/3Co8/Zr10-AC achieved 99.87% HCHO removal efficiency and 82.41% Hg0 removal efficiency at 240 °C, respectively. With increased surface area and pore volume, Zr-AC support facilitated higher dispersion of MnOx-CoOx. Moreover, the co-doping of MnOx-CoOx endowed the sample with more active oxygen species and higher reducibility, which further facilitated the removal of HCHO and Hg0. Chemisorption was proved to predominate in Hg0 removal, and oxidation also worked as Hg2+ was detected in outlet gas. Besides, HCHO predominated in the competition of active oxygen species, especially for lattice oxygen, thus suppressed the Hg0 removal. According to in-situ DRIFTS, HCHO removal proceeded as HCHOads → DOM → formate species → CO2 + H2O, and was boosted by active oxygen species. Furthermore, Mn2/3Co8/Zr10-AC was proved with excellent regeneration performance, indicating its potential in practical application.

A series of MnxFey/AC catalysts synthesized by impregnation method were investigated on the efficient and stable removal of HCHO in the fix-bed reactor. Extensive characterizations, BET, SEM, XRD, H2-TPR, XPS and FT-IR, were conducted to study the physicochemical properties, HCHO oxidation and surface reaction of catalysts. The optimal Mn0.75Fe6.02/AC showed enhanced HCHO removal efficiency of 98.30%, as well as excellent performance for simultaneous removal of HCHO (89.96%) and Hg0 (77.51%). NO and SO2 balanced in N2 would inhibit the removal of HCHO, while the addition of 6% O2 weakened the negative effect of SO2 and NO + 6% O2 facilitated the removal of HCHO. Besides, the slight promotion effect of water vapor was contributed to the regeneration of consumed −OH via the activation of surface oxygen by adsorbed H2O. Characterization results indicated that Mn0.75Fe6.02/AC possessed larger BET surface area, well-developed porosity and better dispersion of active components. Mn0.75Fe6.02/AC exhibited higher reducibility due to the synergistic effect between MnOx and FeOx, and the interaction between Mn-Fe oxides and AC support. At the same time, the oxygen-containing functional groups (C-O-, COO), abundant active surface oxygen and –OH facilitated both adsorption and oxidation of HCHO. Besides, the formate and carbonate intermediates formed on the surface of Mn0.75Fe6.02/AC in HCHO removal process, which could be further oxidized into CO2 and H2O. On the basis of above investigations, the mechanism of enhanced HCHO catalytic removal over MnxFey/AC was proposed.

The effect of CoOx addition on the performance and structure of V2O5/ZrO2–CeO2 catalyst for simultaneous removal of NO and Hg0 in simulated flue gas was investigated by various methods including SEM, BET, XRD, XPS, H2–TPR and FT–IR. It was found that the introduction of CoOx not only greatly enhanced the redox properties of catalysts, but also increased the catalytic performance for simultaneous removal of NO and Hg0. The CoOx–modified V2O5/ZrO2–CeO2 catalyst displayed excellent catalytic activity for NO conversion (89.6%) and Hg0 oxidation (88.9%) at 250 °C under SCR atmosphere. The synergistic effect among vanadium, cobalt, and the ZrCe support could induce oxygen vacancies formation and promote oxygen mobility via charge transfer. Besides, CoOx could assist vanadium species in rapidly changing the valence by the redox cycle of V5+ + Co2+ ↔ V4+ + Co3+. All the above features contribute to the excellent catalytic performance through CoOx addition.

To obtain a new low-cost catalyst that possesses well Hg0 removal activity in a broad temperature range, a series of Cu-Zrx/Cl-BC catalysts were synthesized with the application of bio-char which was activated by NH4Cl. CuO-ZrO2 as the active component largely improved Hg0 removal activity of the catalysts. The catalysts were characterized by SEM-EDX, BET, XRD, H2-TPR, XPS and FT-IR. When the CuO-ZrO2 loading value was 10%, Cu-Zr10/Cl-BC reached the best Hg0 removal efficiency (98.87%) at 120 °C and maintained over 80% until 240 °C. O2 was of benefit to Hg0 removal process especially at high temperature because it could regenerate the lattice oxygen which participated in the removal reaction. In addition, Hg0 removal was mainly determined by adsorption at low temperature and the function of oxidation increased at high temperature. The characterization results indicated that the superior performance of Cu-Zr10/Cl-BC might be ascribed to lower crystallinity, stronger redox ability and better texture properties which resulted from the interaction of CuO and ZrO2. The mechanism for Hg0 removal over Cu-Zr10/Cl-BC was also proposed on the basis of above studies.

A series of low-cost Cu-Mn-mixed oxides supported on biochar (CuMn/HBC) synthesized by an impregnation method were applied to study the simultaneous removal of formaldehyde (HCHO) and elemental mercury (Hg0) at 100–300° C from simulated flue gas. The metal loading value, Cu/Mn molar ratio, flue gas components, reaction mechanism, and interrelationship between HCHO removal and Hg0 removal were also investigated. Results suggested that 12%CuMn/HBC showed the highest removal efficiency of HCHO and Hg0 at 175° C corresponding to 89%and 83%, respectively. The addition of NO and SO2 exhibited inhibitive influence on HCHO removal. For the removal of Hg0, NO showed slightly positive influence and SO2 had an inhibitive effect. Meanwhile, O2 had positive impact on the removal of HCHO and Hg0. The samples were characterized by SEM, XRD, BET, XPS, ICP-AES, FTIR, and H2-TPR. The sample characterization illustrated that CuMn/HBC possessed the high pore volume and specific surface area. The chemisorbed oxygen (Oβ) and the lattice oxygen (Oα) which took part in the removal reaction largely existed in CuMn/HBC. What is more, MnO2 and CuO (or Cu2O) were highly dispersed on the CuMn/HBC surface. The strong synergistic effect between Cu-Mn mixed oxides was critical to the removal reaction of HCHO and Hg0 via the redox equilibrium of Mn4+ + Cu+ ↔ Mn3+ + Cu2+.

To achieve novel sorbent-catalysts with low cost and high activity for removing HCHO in flue gas, we prepared and investigated CuO-CeO2 supported on activated coke granules (CuCe/AC) for decomposition of gaseous formaldehyde (HCHO) from simulated coal combustion flue gas. The results indicated that Cu3Ce8/AC exhibited remarkable conversion performance and good stability for HCHO removal. The presence of NO and SO2 exhibited a slight inhibitive effect on HCHO removal in the presence of 6% O2. The physicochemical properties of CuCe/AC were also studied by combination of N2 adsorption/desorption, SEM, XRD, H2-TPR, XPS and FT-IR. The excellent conversion property of Cu3Ce8/AC was related to the high surface area, large pore volume, high dispersion of copper species, good adsorption capacity and great redox ability of metal oxides. Besides, the synergy between Cu and Ce species improved the mobility of activated oxygen species and the content of chemisorption oxygen, which facilitated the conversion of HCHO greatly. FT-IR results suggested that adsorbed HCHO on the samples surface was oxidized into intermediates, which could be further decomposed into H2O and CO2 by the surface active oxygen of Cu3Ce8/AC. Along with the advantages of Cu3Ce8/AC, it would be a promising material for the removal of HCHO in real industrial application.

To optimize simultaneous control of NO and elemental mercury (Hg0) and gain more insight into the mechanisms, nano-sized TiO2-Al2O3-CeO2 materials synthesized via sol-gel method were used for simultaneous removal of NO and Hg0 from simulated flue gas. The physicochemical characteristics of catalysts were characterized by ICP-OES, BET, XRD, SEM, TEM, XPS, H2-TPR and FT-IR. TiAl10Ce20 nanoparticle with the addition of 10 wt%Al2O3 showed superior NO removal efficiency (93.41%) and Hg0 removal efficiency (80.54%) in the presence of SCR atmosphere at 300 °C. The deactivation effects of 8% H2O and 400 ppm SO2 were also reduced by Al addition. In the presence of SCR atmosphere, the capture of Hg0 was inhibited by the existence of NH3, while the presence of Hg0 had little impact on NO removal. The characterization results showed that the excellent performance of TiAl10Ce20 nanoparticle might result from the stronger redox ability, lower crystallinity and better texture properties with highly dispersed Ce species, which were all attributed to Al addition. The mechanisms for simultaneous removal of NO and Hg0 were also proposed on the basis of above results. TiAl10Ce20 nanoparticle developed in this work was considered to be a promising catalyst for simultaneous removal of NO and Hg0.

The different addition amounts of ZrO2 on CuO-CeO2/TiO2 catalyst synthesized by co-precipitation method were investigated to research the simultaneous removal of Hg0 and NO in simulated flue gas. Results indicated that the CuCe/TiZr0.15 catalyst exhibited the superior Hg0 removal efficiency (72.7%) and prominent NO conversion (83.3%). Hg0 slightly restrained the NO conversion. Except for the effect of the separate NH3 and NO on Hg0 removal, significances of the increased NH3/NO ratio on Hg0 removal and NO conversion were detected. The lower GHSV could give rise to the significant acceleration of Hg0 and NO removal. With the existence of SO2 and H2O, the slightly prohibitive effect on Hg0 and NO removal was displayed. BET, XRD, SEM, H2-TPR, XPS, FTIR analysis were applied to characterize catalysts and the results revealed the ZrO2 modified support on CuO-CeO2/TiO2 resulted in strong redox ability, great mobility of surface oxygen and growing total amount of chemisorbed oxygen and lattice oxygen, which favorably impacted on Hg0 and NO removal. The introduction of Zr benefited great surface area, weakened crystallinity of TiO2 and then improved the dispersion of metal oxide species. More stable Lewis acid sites to form coordinated NH3 were generated due to ZrO2 additive. The synergetic effect through redox equilibrium of C e 3 + + C u 2 + ↔ C e 4 + + C u + contributed to Hg0 removal and NO conversion. In addition, the simultaneous removal of Hg0 and NO on CuCe/TiZr0.15 in terms of detailed mechanism was discussed.

A series of V/ZrCex catalyst synthesized by a co-precipitation method was employed to investigate the simultaneous removal of NO and elemental mercury (Hg0) in simulated flue gas. The catalysts were characterized using BET, SEM, XRD, H2–TPR, XPS, and FT–IR. V/ZrCe0.6 with CeO2/ZrO2 molar ratio of 0.6 showed excellent SCR activity (87.3%) and high Hg0 oxidation efficiency (77.6%) in SCR atmosphere (NH3/NO = 1). The results indicated that the Hg0 had little impact on NO conversion, while the coexistence of NO and O2 would be beneficial for the Hg0 oxidation. Hg0 oxidation was inhibited in SCR atmosphere owing to the presence of NH3. The characterization results demonstrated that the superior performance of V/ZrCe0.6 catalyst might be attributed to lower crystallinity, better texture properties, strong redox ability and high reactive nitrate together with NH3 species. The redox equilibrium (Ce3+ + V5+ ↔ Ce4+ + V4+) contributed to the NO conversion and Hg0 oxidation. The bidentate sulfates formed by adsorbed SO2 could provide new acid sites for NH3 adsorption and increase the amount of NH4+, which reduced the poisoning effect of SO2 and H2O. Based on the experimental results, a mechanism for the simultaneous removal of NO and Hg0 was proposed for the V/ZrCe0.6 catalysts: 2NH3/NH4+(ad) + NO2(ad) + NO(g) → 2N2 + 3H2O + /2H+, Hg(ad) + Oβ → HgO(ad).

Lead oxide (PbO) as one of the typical heavy metals in flue gas from power plants has strong accumulation as well as poisoning effects on SCR catalysts. In this paper, a series of PbO-doped Mn-Ce/TiO 2 catalysts were synthesized by impregnation method. The poisoning effects of PbO over Mn-Ce/TiO 2 samples for selective catalytic reduction of NO by NH 3 were investigated based on catalytic activity test and characterizations. The NO conversion of Mn-Ce/TiO 2 was greatly decreased after the addition of PbO. It was obvious that the NO conversion efficiency of Mn-Ce/TiO 2 catalyst declined from 96.75% to about 40% at 200 °C when Pb:Mn molar ratio reached 0.5. Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Hydrogen temperature programmed reduction (H 2 -TPR), Ammonia temperature programmed desorption (NH 3 -TPD) and Fourier transform infrared spectroscopy (FT-IR) were carried out to study the deactivation reasons of PbO poisoned catalysts. Manganese oxides’ crystallization, less reducible of manganese and cerium oxides, the decreasing of surface area, Mn 4+ as well as Ce 3+ concentration and chemisorbed oxygen (O b ) after the introduction of PbO, all of these resulted in a poor SCR performance. Furthermore, the alteration of acid sites (especially Bronsted acid sites), low ammonia adsorbance, an obvious reducing of ad-NO x species (only a spot of bidentate nitrates remained) and the vanishing of amide species contributed to the deactivation of Mn-Ce/TiO 2 catalyst by PbO doping as well.

To provide insight into optimizing flue gas treatment, simultaneous removal of elemental mercury (Hg0) and NO using a CeO2 modified V2O5–WO3/TiO2 catalyst was investigated. The results show that a novel V2O5–WO3/TiO2–CeO2 catalyst exhibits excellent Hg0 oxidation efficiency (88%) and NO conversion efficiency (89%) at 250 °C. Furthermore, CeO2 modified V2O5–WO3/TiO2 not only exhibits enhanced catalytic activity but also good resistance in SO2 and H2O. These catalysts were also characterized using BET, SEM, XRD, XPS, and H2-TPR. We found lower crystallinity, more reduced species and better texture properties to be presented, which were all ascribed to CeO2 doping. Also, the redox cycle (V4+ + Ce4+ ↔ V5+ + Ce3+) plays a key role in promoting Hg0 oxidation and NO conversion. In tune with the experimental results, a mechanism for the simultaneous removal of Hg0 and NO was proposed for the V2O5–WO3/TiO2–CeO2 catalysts.

Fe2O3 and CeO2 modified activated coke (AC) synthesized by the equivalent-volume impregnation were employed to remove elemental mercury (Hg(0)) from simulated flue gas at a low temperature. Effects of the mass ratio of Fe2O3 and CeO2, reaction temperature, and individual flue gas components including O2, NO, SO2, and H2O (g) on Hg(0) removal efficiency of impregnated AC were investigated. The samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with optimal mass percentage of 3 % Fe2O3 and 3 % CeO2 on Fe3Ce3/AC, the Hg(0) removal efficiency could reach an average of 88.29 % at 110 °C. Besides, it was observed that O2 and NO exhibited a promotional effect on Hg(0) removal, H2O (g) exerted a suppressive effect, and SO2 showed an insignificant inhibition without O2 to some extent. The analysis of XPS indicated that the main species of mercury on used Fe3Ce3/AC was HgO, which implied that adsorption and catalytic oxidation were both included in Hg(0) removal. Furthermore, the lattice oxygen, chemisorbed oxygen, and/or weakly bonded oxygen species made a contribution to Hg(0) oxidation.

A series of Al2O3-modified CuO-CeO2 (CuCeAlx) was synthesized to reveal the effect of Al2O3 addition on catalytic performance and the proposed mechanism for simultaneous removal of NO and toluene at a broad temperature range. BET, XRD, TEM, XPS, NH3-TPD, H2-TPR, and in situ DRIFTS were used to characterize these catalysts. Results demonstrated that Al2O3-modified CuO-CeO2 catalysts showed the excellent NH3-SCR performance at a broad temperature range (200–400 °C) and good low-temperature activity for toluene oxidation. The modification of Al2O3 significantly tunes the physical and textural properties and induces the formation of oxygen vacancies via the interaction between Ce4+/Ce3+ and Cu2+/Cu+ (Ce4+ + Cu+ ↔ Ce3+ + Cu2+). Besides, the inhibition effect of NH3 on toluene oxidation was confirmed in that the active oxygen species reacted preferentially with NH3 rather than the oxidation intermediates of toluene, while NO had a promotional effect on toluene oxidation owing to the reaction of C7H8 + 18NO = 9 N2 + 7CO2 + 4H2O. At the same time, toluene could also be reducing agents of NO, which was beneficial to NH3-SCR reaction, Based on the results, the proposed mechanism for simultaneous removal of toluene and NO over Al2O3-modified CuO-CeO2 catalysts was revealed.

Co–Ce mixed oxides were loaded on commercial cylindrical activated coke granules (CoCe/AC) by an impregnation method to remove gaseous elemental mercury (Hg0) from simulated coal combustion flue gas at low temperature (110–230 °C). Effects of the Co/Ce molar ratio in Co–Ce mixed oxides, mixed oxides loading value, reaction temperature, and flue gas components (O2, NO, SO2, H2O) on Hg0 removal efficiency were investigated, respectively. Brunauer–Emmett–Teller analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) analysis were employed to analyze the characteristics of the samples. Results showed that up to 92.5% of Hg0 removal efficiency could be obtained over Co4.5Ce6/AC at 170 °C. The remarkably high Hg0 removal ability of Co4.5Ce6/AC mainly depended on the synergetic effect between cobalt oxide and ceria. Additionally, different with the pure N2 condition, the existence of O2 and NO...

A series of Ce-doped V 2 O 5 /TiO 2 catalysts synthesized by an ultrasound assisted impregnation method were employed to investigate simultaneous removal of elemental mercury (Hg 0 ) and NO in lab-scale experiments. Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X-ray diffractogram (XRD), and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the samples. Compared to TiO 2 support, the catalytic performance of CeO 2 doped on both TiO 2 and V 2 O 5/ TiO 2 catalysts have been improved. Remarkably, 1%V 2 O 5 –10% CeO 2 /TiO 2 (V1Ce10Ti) exhibited the highest Hg 0 oxidation efficiency of 81.55% at 250 °C with a desired NO removal efficiency under the same condition. Both the NO conversion and Hg 0 oxidation efficiency were enhanced in the presence of O 2 . The activity was inhibited by the injection of NH 3 with the increase of NH 3 /NO. When in the presence of 400 ppm SO 2 , Hg 0 oxidation was slightly affected. Furthermore, Hg 0 removal behavior under both oxidation and selective catalytic reduction (SCR) condition over V1Ce10Ti were well investigated to further probe into the feasibility of one single unit for multi-pollutants control in industry application. The existence of the redox cycle of V 4+ + Ce 4+ ↔ V 5+ + Ce 3+ in V 2 O 5 –CeO 2 /TiO 2 catalyst could not only greatly improve the NO conversion, but also promote the oxidation of Hg 0 .

In order to enhance the catalytic activity for elemental mercury (Hg0) oxidation without the aid of HCl, CeO2 was added into the support to modify V2O5–WO3/TiO2 catalysts. The performance of V2O5–WO3/TiO2–CeO2 (VWTiCe) catalysts on Hg0 oxidation as well as the catalytic mechanism was also studied. The catalysts were characterized by BET, XRD and XPS techniques. The results showed that the performance on Hg0 oxidation was promoted by the introduction of CeO2. NO and SO2 has a promoting effect on Hg0 oxidation in the presence of O2. Besides, the inhibitive effect of NH3 on Hg0 oxidation was confirmed by NH3 consuming the surface oxygen of catalyst. The addition of CeO2 improved the ability to resist H2O. Results also indicated that the Hg0 oxidation efficiencies of V0.80WTiCe0.25 catalysts were thought to be aided by synergistic effect between V2O5 and CeO2. Hg0 oxidation over V0.80WTiCe0.25 follows a Mars–Maessen mechanism where lattice oxygen of V2O5 reacts with adjacently absorbed Hg0.

Mn-Ce mixed oxides supported on commercial columnar activated coke (MnCe/AC) were employed to remove elemental mercury (Hg0) at low temperatures (100–250 °C) without the assistance of HCl in flue gas. The samples were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Effects of some factors, including Mn-Ce loading values, active component, reaction temperatures and flue gas components (O2, SO2, NO, H2O), on Hg0 removal efficiency were investigated. Results indicated that the optimal Mn-Ce loading value and reaction temperature were 6% and 190 °C, respectively. Considerable high Hg0 removal efficiency (>90%) can be obtained over MnCe6/AC under both N2/O2 atmosphere and simulated flue gas atmosphere at 190 °C. Besides, it was observed that O2 and NO exerted a promotional effect on Hg0 removal, H2O exhibited a suppressive effect, and SO2 hindered Hg0 removal seriously when in the absence of O2. Furthermore, the XPS spectra of Hg 4f and Hg-TPD results showed that the captured mercury were existed as Hg0 and HgO on the MnCe6/AC, and HgO was the major species, which illustrated that adsorption and catalytic oxidation process were included for Hg0 removal over MnCe6/AC, and catalytic oxidation played the critical role. What's more, both lattice oxygen and chemisorbed oxygen or OH groups on MnCe6/AC contributed to Hg0 oxidation. MnCe6/AC, which exhibited excellent performance on Hg0 removal in the absence of HCl, appeared to be promising in industrial application, especially for low-rank coal fired flue gas.

This work addressed the investigation of activated coke (AC) treated by acids. Effects of AC samples, modified by ether different acids (H2SO4, HNO3 and HClO4) or HClO4 of varied concentrations, on Hg0 removal were studied under simulated flue gas conditions. In addition, effects of reaction temperature and individual flue gas components including O2, NO, SO2 and H2O were discussed. In the experiments, Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were applied to explore the surface properties of sorbents and possible mechanism of Hg0 oxidation. Results showed that AC sample treated by HClO4 of 4.5 mol/L exhibited maximum promotion of efficiency on Hg0 removal at 160 °C. NO was proved to be positive in the removal of Hg0. And SO2 displayed varied impact in capturing Hg0 due to the integrated reactions between SO2 and modified AC. The addition of O2 could improve the advancement further to some extent. Besides, the Hg0 removal capacity had a slight declination when H2O was added in gas flow. Based on the analysis of XPS and FTIR, the selected sample absorbed Hg0 mostly in chemical way. The reaction mechanism, deduced from results of characterization and performance of AC samples, indicated that Hg0 could firstly be absorbed on sorbent and then react with oxygen-containing (C O) or chlorine-containing groups (C Cl) on the surface of sorbent. And the products were mainly in forms of mercuric chloride (HgCl2) and mercuric oxide (HgO).

Catalytic technologies present a more environmentally and financially sound option in the removal of elemental mercury (Hg0) from coal-fired flue gas. However, developing novel and efficient catalysts for Hg0 oxidation is still a challenge. This paper reviews the catalytic oxidation of Hg0 over a new kind of catalysts which were developed from selective catalytic reduction (SCR) catalysts of NOx. In this review, both noble metal catalysts and non-noble metal catalysts for Hg0 oxidation were summarized. An overview of mercury emissions including transformation and speciation of mercury in coal-fired flue gas was also presented. The possible mechanisms and kinetics of mercury oxidation, space velocity and the effects of flue gas components on activity and stability of the catalysts were examined. We expect that this work will serve as a theoretical underpinning for the development of Hg0 oxidation technology in flue gas.

A series of low-cost Cu-Mn-mixed oxides supported on biochar (CuMn/HBC) synthesized by an impregnation method were applied to study the simultaneous removal of formaldehyde (HCHO) and elemental mercury (Hg

In order to implement Hg 0 control strategy in a wet scrubber, oxidation of elemental mercury (Hg 0 ) in the simulated coal-fired flue gas by UV/Fenton system was investigated. Effects of different operation parameters have been studied, including initial solution pH, H 2 O 2 , TiO 2 and Fe 2+ concentration, solution temperature, gas flow rate and flue gas components (O 2 , SO 2 and NO). The main ion products in the solution have been analyzed. The experimental results suggested that oxidation of Hg 0 was inhibited with the increase of initial solution pH and gas flow rate. Additionally, with the increase of the H 2 O 2 , TiO 2 , Fe 2+ concentration and solution temperature, the Hg 0 oxidation efficiency was enhanced to the maximum at first and then decreased. Hg 0 oxidation can be significantly inhibited by SO 2 and NO when the flue gas was absence of O 2 , but the oxidation capacity was recovered with 9% O 2 exist in the flue gas. SO 2 showed an inhibition effect on Hg 0 oxidation, while the inhibition was weakened at higher SO 2 concentration. Different NO concentration had an insignificant effect on Hg 0 oxidation process under the experimental conditions. In the case of presence and absence of flue gas components (9% O 2 , 800 ppm SO 2 , 600 ppm NO) and under the optimal conditions (pH = 1, [H 2 O 2 ] = 0.05 mol/L; [TiO 2 ] = 0.6 g/L; [Fe 2+ ]/[H 2 O 2 ] = 1/2; T = 40 °C), the average oxidation efficiency of Hg 0 can reach to 94.4% and 98.5%, respectively.

Fe2O3 and CeO2 modified activated coke (AC) synthesized by the equivalent-volume impregnation were employed to remove elemental mercury (Hg(0)) from simulated flue gas at a low temperature. Effects of the mass ratio of Fe2O3 and CeO2, reaction temperature, and individual flue gas components including O2, NO, SO2, and H2O (g) on Hg(0) removal efficiency of impregnated AC were investigated. The samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with optimal mass percentage of 3 % Fe2O3 and 3 % CeO2 on Fe3Ce3/AC, the Hg(0) removal efficiency could reach an average of 88.29 % at 110 °C. Besides, it was observed that O2 and NO exhibited a promotional effect on Hg(0) removal, H2O (g) exerted a suppressive effect, and SO2 showed an insignificant inhibition without O2 to some extent. The analysis of XPS indicated that the main species of mercury on used Fe3Ce3/AC was HgO, which implied that adsorption and catalytic oxidation were both included in Hg(0) removal. Furthermore, the lattice oxygen, chemisorbed oxygen, and/or weakly bonded oxygen species made a contribution to Hg(0) oxidation.

Industrial grade titanium modified by ion implantation and sputtering was used as electrodes. The effect of ion beam modification on the electrochemical behavior and surface structure of electrodes was investigated. Also discussed is the hydrogen evolution process of the electrode in acidic solution. Several ions such as Fe+, C+, W+, Ni+ and others, were implanted into the electrode. The electrochemical tests were carried out in 1N H2SO4 solution at 30±1 °C. The electrode potential was measured versus a saturate calomel electrode as a function of immersion time. The cathodic polarization curves were measured by the stable potential static method. The surface layer composition and the chemical state of the electrodes were also investigated by Auger electron spectrometer (AES) and X-ray photoelectron spectroscopy (XPS) technique. The results show that: (1) the stability of modified electrodes depends on the active elements introduced by ion implantation and sputtering deposition. (2) The hydrogen evolution activity of industrial grade titanium may be improved greatly by ion beam modification. (3) Ion beam modification changed the composition and the surface state of electrodes over a certain depth range and forms an activity layer having catalytic hydrogen evolution, which inhibited the absorption of hydrogen and formation of titanium hydride. Thus promoted hydrogen evolution and improved the hydrogen evolution catalytic activity in industrial grade titanium.