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The dependency on morphology is crucial for achieving highly efficient direct decomposition of NO. Herein, a BaCoO 3 /CeO 2 catalyst is synthesized using CeO 2 small particles (p), spheres (s) and rods (r) as supports. The NO conversion to N 2 (NTN2) at 800 °C follows the order BaCoO 3 /CeO 2 -r (78.8 %) > BaCoO 3 /CeO 2 -s (75.9 %) > BaCoO 3 /CeO 2 -p (56.9 %) > BaCoO 3 (8.6 %) at a space velocity 1 g s/cm3. BaCoO 3 /CeO 2 -r exhibts high tolerance to O 2 and stability with conversion decreasing from 78.8 % to 74.6 %, 60.0 % and 50.0 % at 800 °C with 1, 5 and 10 vol% O 2 , respectively. The high redox activity, higher active oxygen mobility and NO adsorption capability ensures its superior performance, while the high surface area (31.29 m2/g) and uniform distribution of active sites on the surface further promote the activity. The mechanism of NO direct decomposition is elucidated by in situ Diffuse reflectance infrared Fourier transform spectroscopy, 18O 2 isotopic transient exchange experiments and density functional theory (DFT) calculation. [Display omitted] • CeO 2 of different microstructures were used as catalyst supports. • The structure-activity relationship was investigated. • The high NO to N 2 conversion reached at 78.8 % at 800 °C over BaCoO 3 /CeO 2 -r. • The intermediate and competitive adsorption of NO and O 2 were discussed. • The reaction pathways with/no O 2 in NO direct decomposition were elaborated. [ABSTRACT FROM AUTHOR]

The CuMn/ZSM-5 (CM/Z), CuMn/Beta (CM/B), and CuMn/SSZ-13 (CM/S) catalyst samples were prepared via an excess impregnation method to investigate the metal-support effect. The results show that the activity at 550 °C for NO direct decomposition follows the order of CM/Z (53.4%) > CM/B (49.2%) > CM/S (7.9%). The good activity and stability of CM/Z are attributed to a strong support effect including forming more active copper sites of the (Cu2+-O2--Cu2+)2+ and (Cu+-□-Cu+)2+ dimers, which have higher redox activity, capacity of oxygen mobility, and NO sorption capability. The competitive adsorption between NO and O 2 on the oxygen vacancy of dimers over CM/Z results in the activity decrease from 53.4% to 40.3% at 550 °C after adding 1 vol% O 2. The reaction mechanism over CM/Z was discussed based on the in situ DRIFT and isotopic (18O 2) experiments. Two NO adsorbs firstly on (Cu+-□-Cu+)2+ to form N 2 O, and N 2 O is activated to produce N 2 , followed by the NO adsorption on (Cu2+-O2--Cu2+)2+ to form nitrite and nitrate species and decomposition to NO and O 2. [Display omitted] ● The support effect of ZSM-5, Beta, and SSZ-13 supported CuMn is examined. ● CuMn/ZSM-5 exhibits a high NO to N 2 conversion of 53.4% at 550 °C. ● The intermediate species and competitive adsorption of NO and O 2 are discussed. ● The reaction pathways for NO direct decomposition are proposed. [ABSTRACT FROM AUTHOR]

Studying the mechanisms of bagasse conversion into syngas is essential to sustain the growing use of biomass in energy economy production. In this work, the precise kinetics of bagasse gasification with various gasification agents was firstly investigated employing in-situ infrared spectra with Coats-Redfern integration, combining qualitative infrared spectroscopy allowed for kinetic analysis, so as to explore how the intermediate species vary in each basic reaction. The results demonstrate that the CO 2 agent reduces the activation energy of nitryl after amino oxidation, making the lignin involved in gasification more easily as well as causing higher gasification efficiency. On the one hand, steam serving as a gasification agent enhances the concentration of hydroxyl groups and produces H 2 -rich syngas. On the other hand, the strong oxidizing hydroxyl group reduces the energy barrier of carbonyl and carboxyl groups in cellulose, which facilitates the gasification process. Furthermore, this study compared the effects of gasification agent (H 2 O or CO 2) on syngas composition, reactor temperature distribution, carbon conversion rate, gasification efficiency, as well as low calorific value, providing essential information for understanding the micro-reaction pathways and pathway regulation during bagasse gasification. • Reducing the activation energy of functional groups are regulated by gasifiers. • The synergistic of gasification agents regulate chemical bond-breaking pathways. • The prospects of producing H 2 from biomass gasification are elucidated. [ABSTRACT FROM AUTHOR]

The CuO/Ce 0.75 Zr 0.25 O 2 - δ and Ce 0.75 Zr 0.25 O δ catalysts were prepared by the sol-gel method, and Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ was obtained by treating CuO/Ce 0.75 Zr 0.25 O 2 - δ with nitric acid to remove the well-dispersed CuO on the surface. Various characterizations were used to reveal the different active sites, such as surface-dispersed CuO and Cu-Ce-Zr-O δ solid solutions in CuO/Ce 0.75 Zr 0.25 O 2 - δ , Cu-Ce-Zr-O δ solid solutions in Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and Ce-Zr-O δ solid solutions in Ce 0.75 Zr 0.25 O δ . The Raman and O 2 -TPD results showed that the concentration of oxygen vacancies in Cu-Ce-Zr-O δ solid solutions was higher than that in Ce-Zr-O δ solid solutions. CO oxidation testing suggested that the catalytic activity decreases in the order of CuO/Ce 0.75 Zr 0.25 O 2 - δ > Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ > Ce 0.75 Zr 0.25 O δ . Combined with the in situ diffuse-reflectance Fourier transform (in situ DRIFT) results, the reaction sensitivity followed the order of CO linear chemisorption onto dispersed CuO x species (Mars-van Krevelen mechanism) > carbonate species onto a Cu-Ce-Zr-O δ solid solution (Langmuir-Hinshelwood mechanism) > carbonate species onto a Ce-Zr-O δ solid solution (Langmuir-Hinshelwood mechanism). Kinetic studies suggested that the power-law rate expressions and apparent activation energies were r = 6.02 × 10 −7 ×P CO 0.68 P O2 0.03 (53 ± 3 kJ/mol) for CuO/Ce 0.75 Zr 0.25 O 2 - δ , r = 5.86 × 10 −7 ×P CO 0.8 P O2 0.07 (105 ± 5 kJ/mol) for Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and r = 5.7 × 10 −7 ×P CO 0.75 P O2 0.12 (115 ± 6 kJ/mol) for Ce 0.75 Zr 0.25 O δ . The Mars-van Krevelen mechanism should be the crucial reaction pathway over CuO/Ce 0.75 Zr 0.25 O 2 - δ in CO interfacial reactions, although the Langmuir-Hinshelwood mechanism cannot be ignored, and the Langmuir-Hinshelwood mechanism mainly occurred over the Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and Ce 0.75 Zr 0.25 O δ catalysts, where the contribution from the Mars-van Krevelen mechanism was negligible due to the absence of surface CuO x species. [ABSTRACT FROM AUTHOR]

Self-sustained catalytic combustion is a promising strategy to remove CO from the off-gas produced during steelmaking, where the potential catalysts are bulk copper-cerium-zirconium mixed oxides or those supported on TiO 2 or ZSM-5 substrates. In this study, the effects of the catalyst support on the CO catalytic ignition performance and reaction pathways were investigated by FTIR coupled with a novel in-situ cell, together with the state-of-the-art characterization techniques. The Infrared (IR) transmission cell equipped with a magnetically driven system, could effectively prevent overlaps between active intermediate peaks (Cu+-CO and Cu+(CO) 2) and gaseous CO peaks. The Cu+ cations located at the phase interface are the main active sites. The Cu and Ce interactions lead to the formation of solid solutions of CuCe 0.75 Zr 0.25 O δ (CuCeZr). The monocarbonyls [Cu+-CO] are the dominant species during CO oxidation, and the vacancies in the solid solutions are occupied by oxygen, accelerating the oxygen cycle. The TiO 2 or ZSM-5 supports promote copper dispersion over CuCe 0.75 Zr 0.25 O δ /TiO 2 (CuCeZr/T) and CuCe 0.75 Zr 0.25 O δ /ZSM-5 (CuCeZr/Z) catalysts, which can be attributed to their high surface areas (168.2 and 346.3 m2/g, respectively), while the Cu-Ce interactions are less relevant. Hence, CO oxidation mainly occurs at the phase interface between copper oxide and TiO 2 /ZSM-5. Dicarbonyls [Cu+(CO) 2 ] are the main intermediates for the CuCeZr/T and CuCeZr/Z catalysts, and the Cu2+ species are reduced to form dicarbonyls that also take part in the oxidation process. Although a well copper dispersion enhances the activity of individual copper sites on the CuCeZr/T and CuCeZr/Z catalysts, considering the redshift of the carbonyl bands and the increase in CO adsorption, the close interactions and high contents of Cu and Ce favor the local accumulation of heat and mass transfer over bulk CuCeZr, leading to the ignition of CO at low temperatures. [Display omitted] • CuCe 0.75 Zr 0.25 O δ and CuCe 0.75 Zr 0.25 O δ /TiO 2 and CuCe 0.75 Zr 0.25 O δ /ZSM-5 catalysts were designed. • The structure-activity relationship was obtained. • The self-sustained combustion and stability limit of CO were carried out. • The in-situ IR with a novel magnetically driven IR cell was designed and performed. • The intermediate species and reaction pathways over different catalysts were evidenced. [ABSTRACT FROM AUTHOR]

Long-flame coal is a typical low-ranked coal that is not fully utilized and has a huge global reserve. High-content oxygen is a significant negative factor for low-rank coal utilization. The TG–FTIR–GC/MS method was applied to investigate the migration behavior of oxygen and the variation in the properties of Chinese long-flame coal during low-temperature pyrolysis. It was found that the oxygen migration ratios in long-flame coal toward gas and tar were 47.7 and 5.2%, respectively, at 550 °C, that the initial oxygen migration temperatures of hydroxyl, carboxyl, carbonyl and ether bonds were 500, 200, 300 and 350 °C, respectively, that the decomposition rates were 8.2, 90, 99.2 and 86% at 550 °C, respectively, that the oxygen in gas existed mainly in the form of CO2 and CO, and that the oxygen in tar existed mainly in the form of phenolic compounds. The further removal of oxygen was due to the decomposition of hydroxyl and a small amount of stable ether bonds. Furthermore, deoxygenation suggested that the decrease in oxygen had a positive effect on coal liquefaction and resulted in a decrease in its hydrophilicity. [ABSTRACT FROM AUTHOR]

Catalytic combustion (CC) and chemical looping combustion (CLC) are promising technologies for energy saving and emission reduction of CO 2 in treatment of steelmaking off-gas. This work firstly reports and compares the evolution behavior and quantitative reaction mechanisms of cube Cu 2 O model catalyst for CC and CLC reactions. The Cu 2 O-CC exhibited the higher activity and stability than Cu 2 O-CLC. The typical characterization results suggested that the only surface unstable Cu 2 O was oxidized to CuO, and the excellent synergistic effect of metal-oxide interface (100) between Cu+/Cu2+ and active lattice oxygen species for Cu 2 O-CC reaction. But, for CLC reaction, Cu 2 O structure was collapsed, which caused the agglomeration of CuO x species and gradual decrease of reaction stability. Three different active oxygen species (surface cycle lattice oxygen, bulk lattice oxygen, and adsorbed oxygen) and the detailed reaction pathways were proposed by the in situ IR spectroscopy, isotopic (18O 2) transient exchange experiments and DFT simulation. The intrinsic activity of surface cycle lattice oxygen was higher in terms of TOF (13.5 × 10−3 s−1) and facile formation of C16O18O on the cubic interface of Cu 2 O-CC through adsorbed CO during CC process. The contribution degrees of Mars-van-Krevelen (M-K) and Langmuir–Hinshelwood (L-H) mechanisms for CC and CLC reactions were 76.6% and 23.4% for CC, and 89.7% and 10.3% for CLC on Cu 2 O catalyst, respectively. [Display omitted] • The cube Cu 2 O model catalyst was well prepared by liquid-phase reduction method. • The detailed evolution behavior and structure-activity relationship of cube Cu 2 O was carried out for CC and CLC reactions. • The roles of three different active oxygen species in CC and CLC reactions were clearly distinguished. • The contribution degrees of Mars-van-Krevelen and Langmuir–Hinshelwood mechanisms for CC and CLC reaction were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The controllable morphology synthesis of hexagonal WO 3 (HWO) was achieved by commercial bacterial cellulose (C). • The obtained V 2 O 5 /HWO-C catalyst exhibits effective resistance to K poisoning and SO 2 , and follows the Langmuir-Hinshelwood mechanism. • The detailed alkali metal-resistant pathways for the distribution of alkali metal ions (K+) on the K-V 2 O 5 /HWO-C catalyst were proposed. A series of V 2 O 5 /HWO catalysts are prepared by hydrothermal and impregnation methods using different precursors, among which the V 2 O 5 /HWO-C catalyst exhibited the optimal NH 3 -SCR performance. Compared to oxalic acid (O) and water (W), commercial bacterial cellulose (C) as a precursor can firstly achieve a more controllable synthesis to form hexagonal WO 3 (HWO) of V 2 O 5 /HWO-C catalyst. Various characterization (XRD, N 2 -BET, TEM, SEM, XPS, EDX mapping, and NH 3 /NO-TPD-MS) indicate that a higher specific surface area, abundant active oxygen and surface acidity result from the V 2 O 5 /HWO-C catalyst. The reason is that HWO-C has an excellent and smooth rod-shaped morphology, which promotes high dispersion of V 2 O 5 on its surface. In situ IR results show that the SCR follows the Langmuir-Hinshelwood (L-H) mechanism, where absorbed NO x intermediate species are formed on the V 2 O 5 and react with the NH 4 + and NH 3abs groups of V 2 O 5 and HWO. After loading 1.75 wt% K+, the obtained K-V 2 O 5 /HWO-C catalyst exhibits effective resistance to K poisoning and SO 2 , and retains 78 % NO x conversion efficiency at 360 °C after 10 h, attributed to the effective capture of K+ (1.04 wt%) in HWO-C channels via a new pathway, although approximately 0.71 wt% K+ are located on HWO-C external surface with weak bonding to V 2 O 5. [ABSTRACT FROM AUTHOR]

• The powder sample is well designed and coated on the HC tube to form CuCe 0.75 Zr 0.25 O δ /HC catalyst. • The transient changes and two-dimensional temperature region are obtained for CO self-combustion via CO-TPO + FLIR. • The various intermediate species and competitive adsorption of reactants on different active sites are evidenced. • The different pathways and roles of M-K and L-H mechanisms are proposed using in situ IR. A CuCe 0.75 Zr 0.25 O δ catalyst was prepared by the sol-gel method and successfully coated on honeycomb ceramic (HC) carrier. The activity of CuCe 0.75 Zr 0.25 O δ /HC was determined by the CO-TPO + FLIR, with the results performing that the critical condition for CO self-sustained combustion is 3 vol% CO + 3 vol% O 2 /N 2 at 0.5 L/min. As the CO concentration increases from 1 vol% CO to 3 vol% CO, the induction process (T 15) shifts to rapid ignition with a transient change for the CO oxidation reaction. The furnace temperature for CO self-sustained combustion decreases with increasing the CO and O 2 concentrations. Upon increasing the CO 2 concentration, however, furnace temperature is needed to increase and realize CO complete conversion. The thermal stability test combined with SEM + EDX results indicate that the CuCe 0.75 Zr 0.25 O δ /HC retains an excellent thermal stability after a 200 h, and the high-temperature region remains at 225 ± 1 °C during the CO self-combustion reaction. The activity of catalyst is reduced slightly after the 200 h test because of the carbon deposition on the catalyst surface, but such a slight deactivation can be eliminated by the air oxidation method. In situ IR results show a competitive adsorption of CO/O 2 and CO 2 on the Cu-Ce active sites, indicating that the addition of gaseous CO 2 performs an inhibition of CO oxidation. CO preferentially adsorbs linearly at Cu+ sites to form carbonyls that react with lattice oxygen to produce CO 2 to release, which can be ascribed to M-K mechanism. The L-H mechanism is less important, which involves the relatively weak reaction of adsorbed CO and adsorbed oxygen on the Cu-Ce active sites to form carbonate species. [ABSTRACT FROM AUTHOR]

Large-scale internally circulating flows of gas and particles might form under unevenly distributed fluidized air in a fluidized bed. Compared with bed materials, the present study investigated dissimilar particles with different sizes and density moving and mixing through the developed image technique in an internally circulating fluidized bed (ICFB). The concentrations of the tracer particles were obtained by the image analysis method. The inhomogeneity degree and lateral dispersion coefficients of the tracer particles were also calculated, with the results indicating that the degree of inhomogeneity decreases with the increasing dispersed time. The lateral dispersion coefficients of tracer particles with a lower density (for a similar diameter) are larger than those with a higher density. It is clear that the different air distribution methods play an important role in the lateral dispersion of the tracer particles. [ABSTRACT FROM AUTHOR]

An innovative simplified modification method for red mud had been proposed, which enabled its utilization as an active Fe 2 O 3 -rich component for catalytic oxidation of toluene. The Box-Behnken design, based on Response Surface Methodology (RSM), was employed to optimize the modification of bauxite residue using oxalic acid combined with UV irradiation. Based on the experimental conditions, the optimal conditions for three independent parameters were determined: acid leaching time (2 hours), UV irradiation time (1 hour), and acid dosage (150 ml),which was in order to enhance the maximum catalytic efficiency of toluene at 300 °C. Under the optimal preparation conditions provided by the Box-Behnken design, the catalytic efficiency of toluene at 300°C could reach 99.2%. In comparison to the acid-modified mud (MRM) and untreated bauxite residue (RM), the aluminum refinery residue modified with oxalic acid-assisted UV irradiation (MRM-UV) exhibited the formation of oxalate sub-iron precipitates, resulting in significantly lower catalytic temperatures (238°C). Furthermore, through XRF, XRD, XPS, O 2- TPD, and H 2 -TPD analysis, it was discovered that a large amount of iron oxide and calcium oxide formed CaO+Fe 2 O 3 →Ca 2 Fe 2 O 5 , strengthening the interaction between iron and calcium, augmenting the migration rate of lattice oxygen from the bulk phase to the surface. Consequently, T 50 were reduced by 20.9% and 31.8% when compared to MRM and RM. Moreover, the CO 2 selectivity of MRM-UV increased from 8.6% to 70.5% compared to RM at 300°C. Using in situ DRIFTS, the reaction pathway of toluene on MRM-UV was identified as benzyl alcohol → benzaldehyde or benzoyl → benzoate→maleic anhydride→CO 2 and H 2 O. The process refinement reduced VOCs emissions and promoted sustainable waste management by combining oxalic acid with catalytically active red mud. [Display omitted] • Organic acid assisted UV modified red mud as a catalyst. • Optimizing red mud catalyst using RSM, screening optimal preparation conditions. • A modified red mud catalyst with Fe 2 O 3 and Ca 2 Fe 2 O 5 as active components. [ABSTRACT FROM AUTHOR]

Catalytic oxidation technology is a promising strategy to eliminate carbon monoxide (CO), volatile organic compounds (VOC) and other emissions from industrial boilers and to address ammonia (NH 3) escape. Herein, we demonstrate the potential of copper-cerium-zirconium mixed oxides or those supported on TiO 2 or ZSM-5 substrates for the simultaneous catalytic removal of CO, toluene and NH 3. Among them, CuCeZr/ZSM-5 exhibits the best co-processing ability for mixed gases. In situ infrared spectroscopy analyses suggest that there is a competitive adsorption among CO, toluene and NH 3 , and the inhibition is in descending order of toluene＞CO＞NH 3. Based on the physical-chemical characterizations, the Cu-Ce interfacial structure plays an important role in CO ignition at low temperatures. More importantly, the abundant acidic sites on the ZSM-5 support can improve the stability of adsorbed NH 3 at high temperatures, resulting in the best NH 3 catalytic oxidation performance of CuCeZr/ZSM-5 with no secondary pollutants of NO x. This study provides a strategy for the catalyst design to eliminate multiple pollutants targeting the properties of pollutants. [Display omitted] • Simultaneous removal of CO, toluene and NH 3 was achieved by CuCeZr based catalyst. • The best mixed gas treatment was observed for CuCeZr/ZSM-5 catalyst. • Cu-Ce interfacial structure allows preferential ignition of CO at low temperature. • The acidic sites on the ZSM-5 promoted the adsorption and oxidation of NH 3. [ABSTRACT FROM AUTHOR]

• Semi-quantitative analysis of 23Na CP/MAS NMR were conducted. • Molecular occurrence model of sodium was constructed via computational chemistry. • Adsorption position of sodium was investigated by computational chemistry. • The real way of organic sodium bonding to the coal was discussed and observed. Detailed intrinsic sodium occurrence for future research on migration, release, and catalyst effect behavior of sodium is necessary. Complementary characterizations, such as 13C CP/MAS NMR, FT-IR, 23Na CP/MAS NMR, XPS, elemental composition analysis, and sequential extraction experiments, were employed to elucidate the actual compound form of sodium as well as Zhundong coal's structural features. Thus, a molecular occurrence model of sodium in Zhundong coal was constructed based on its structural characteristics via computational chemistry. The occurrence model of alkali metals in Zhundong coal, including their compound form, relative content, and distribution properties, was investigated at the microstructural level. Preliminary results show that the amorphous cell formula of Zhundong coal is (C 2080 H 980 O 380 N 30 S 10 Na) n. Organic oxygen in Zhundong coal was 67.7% hydroxyl (ethoxy), 15.5% carbonyl, and the remaining 16.8% was attributed to carboxyl. Combined with the 23Na CP/MAS NMR and sequential extraction experiment, organic sodium accounts for 18.01% of the total. Most inorganic sodium (81.99%) is present as hydrated sodium ion (75.08%), while a small part is present as NaCl crystal phase (3.34%) insoluble-sodium account for 3.57%. Calculated 13C NMR, FT-IR, and 23Na NMR spectra of the proposed model agree well with the experimental spectra suggesting that the molecular occurrence model of sodium in Zhundong coal is a particularly convincing model at the approximate condition of statistical average. The highest negative electrostatic potential area is near the carboxyl group and may be attributed to organic sodium absorption sites; the hydroxy or phenoxy group nearby may form additional coordination bonds to sodium, indicating the reflection of the complexity of the Na chemical environment as concluded from 23Na CP/MAS NMR. [ABSTRACT FROM AUTHOR]

• The LMO-W, LMO-SW, LCMO-W, LCMO-SW, LSMO-W and LSMO-SW catalysts were well designed by precursors. • The Binary search was used to determine the lean-combustion limits for the self-sustained combustion of CO. • The stability of the LCMO-SW catalyst was evaluated under CO oxidation at the furnace temperature of 535 °C. • The influence mechanism of self-sustaining combustion stability of CO catalyst was investigated and put forward. • The L-H mechanisms were performed for SCR reaction over the catalysts via in situ IR experiments. The LaMnO 3 , La 0.9 Ce 0.1 MnO 3 and La 0.9 Sr 0.1 MnO 3 catalysts are synthesized using sugar agent, and the CO self-sustained combustion is investigated, where the catalytic performance is decided by temperature with CO conversions of 10% (T 10), 50% (T 50), and 90% (T 90). The results show that self-sustaining combustion is successfully realized on the catalyst, and the order of activity decrease is as follows: La 0.9 Ce 0.1 MnO 3 (with sugar) > La 0.9 Sr 0.1 MnO 3 (with sugar) > LaMnO 3 (with sugar) > LaMnO 3 (without sugar) > La 0.9 Sr 0.1 MnO 3 (without sugar) > La 0.9 Ce 0.1 MnO 3 (without sugar). Combined with the results of XPS, H 2 -TPR, O 2 -TPD and CO-TPD techniques, the excellent activity of La 0.9 Ce 0.1 MnO 3 (with sugar) can be attributed to the high content of Mn4+ ions and reactive oxygen vacancies enriched on the catalyst surface, sound low-temperature reduction, and uniform dispersion. Besides, in situ IR spectroscopy results indicate that the catalytic combustion of CO over manganese-based perovskite catalysts follows the L-H mechanism: the chemisorption of CO and O 2 takes place to produce monodentate carbonates and bicarbonate species, which then decompose to yield CO 2 release. The high-temperature stability test provides evidence that the La 0.9 Ce 0.1 MnO 3 (with sugar) gives 100% CO conversion and that the activities remain almost unchanged after reaction for 12 h, where the temperature of catalyst bed reaches about 717 °C. The results obtained are helpful to accept this technology on efficient and clean energy utilization in iron and steel industry. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) and catalytic combustion (CC), which are potential technologies to promote CO→CO 2 efficient conversion and energy conservation for the steelmaking off-gas, are investigated in reaction activity, structure evolution catalysts/oxygen carriers (OCs) and energy recovery using Cu/CeO 2 materials. Activity results suggest that the rod-shaped samples with well-defined (100) crystal faces exhibit higher activity than the sphere-shaped samples with (111) crystal faces, obtaining the optimized copper content of 3 wt%. IR spectra confirmed the proposed reaction pathway that the CO adsorbed on copper sites (Cu+–CO) at the Cu–Ce interface reacts with adjacent surface lattice oxygen. The gaseous oxygen continuously migrates to the external surface of materials, thus resulting in strongly exothermic CO self-sustained combustion during CC. Such a violent reaction does not cause obvious evolution of chemical composition, crystalline phase and structure. Since the active lattice oxygen is gradually consumed but not replenished by external gaseous O 2 in time, CO combustion is not self-sustained during CLC. Therefore, the reduction cycle is no longer confined to the surface of the material but penetrates deep into its body, which accelerates Cu+ enrichment at the surface and leads to irreversible sintering and agglomeration of the material. • The activity of nanorod and nanosphere Cu/CeO 2 was compared. • CLC reaction is more exergy efficiency when burning. • The reason of catalyst deactivation in CLC was investigated. • The migration of active oxygen species in CC and CLC was compared. [ABSTRACT FROM AUTHOR]

The reaction pathways of CO oxidation over the (1 0 0), (1 1 0) and (1 1 1) crystal planes of Cu 2 O. • Morphologies of Cu 2 O micro/nanocrystals were controlled by simply changing precursor concentration. • Increase of precursor concentration results in more exposure of active crystal plane of Cu 2 O. • Activity of CO self-sustained catalytic combustion on Cu 2 O increases with precursor concentration. • Coordination unsaturated Cu and O on the (1 1 1) and (1 1 0) planes promote CO oxidation. The self-sustained catalytic combustion is one of the most effective ways to remove high concentration CO at low temperature. In this paper, Cu 2 O micro/nanocrystals with different morphologies were successfully synthesized by changing the precursor concentration using liquid phase reduction method. The obtained Cu 2 O were characterized using SEM, XRD, XPS, H 2 -TPR and O 2 -TPD, and the relationship between the catalytic performance and morphology was analyzed based on CO-TPD-MS and activity evaluation results. It was found that high precursor concentration leads to more exposure of active crystal planes of Cu 2 O. Compared with Cu 2 O-1 exposing only (1 0 0) crystal planes, Cu 2 O-5, the precursor concentration of which is 5 times of Cu 2 O-1, exposes (1 0 0) and (1 1 0) crystal planes. Cu 2 O-9, with 9 times of precursor concentration of Cu 2 O-1, exposes (1 0 0), (1 1 0) and (1 1 1) crystal planes simultaneously. All the obtained Cu 2 O with different precursor concentrations can achieve self-sustained CO catalytic combustion, and the catalytic activity increases with increasing precursor concentration (Cu 2 O-1 < Cu 2 O-5 < Cu 2 O-9). The results prove that unsaturated coordination of Cu and O on the (1 1 1) and (1 1 0) planes can enhance the corresponding reducibility, adsorption and activation of gaseous oxygen, consequently promoting the CO oxidation to CO 2 over Cu 2 O-9. [ABSTRACT FROM AUTHOR]