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In recent years, with global climate change, the utilization of carbon dioxide as a resource has become an important goal of human society to achieve carbon peaking and carbon neutrality. Among them, the catalytic conversion of carbon dioxide to generate renewable fuels has received great attention. As one of these methods, photocatalysis has its unique properties and mechanism, which can only rely on sunlight without inputting other energy. It is an emerging discipline with great development prospects. The core of photocatalysis lies in the development of photocatalysts with high activity, high selectivity, low cost, and high durability. This review first introduces the background and mechanism of photocatalysis, then introduces various types of photocatalysts based on different substrates, and analyzes the methods and mechanisms to improve the activity and selectivity of photocatalysts. Finally, combining the plasmon effect with photocatalysis, the review analyzes the promoting effect of the plasmon effect on the photocatalytic carbon dioxide synthesis of renewable fuels, which provides a new idea for it. [ABSTRACT FROM AUTHOR]

In response to stricter emission regulations, lean‐burn engines have attracted more and more attention. However, lean burn engines would inevitably lead to the increase in NOx emissions. The researchers combined Three‐Way Catalyst (TWC) and Selective Catalytic Reduction (SCR) to propose "passive SCR", which makes the engine periodically switch between rich and lean burn. During rich combustion, ammonia is produced by the TWC catalyst, stored in the downstream SCR, and reacts with NOx during lean combustion, in which increasing the ammonia yield on the TWC catalyst is the key. In this study, the self‐propagating high‐temperature synthesis method was used to modify the catalyst by adding copper to improve the ammonia production efficiency. The conversion rate of catalysts with different copper doping ratios from NO to ammonia was measured. Through XRD, BET, H2‐TPR, TEM, HRTEM, XPS, in‐situ DRIFTS, etc. the improvement mechanism of copper doping was analysed. The results showed that Pt0.01Cu0.1Ce0.45Zr0.45Ox had the highest catalytic activity, the widest reaction temperature window (300–550 °C) with the conversion greater than 96 %. The characterization results showed that appropriate amount of copper doping can adjust the valence distribution, form more oxygen vacancies, and improve the distribution of active species. The in‐situ DRIFTS further demonstrated that the conversion from bridged to monodentate and bidentate nitrate may be the key factors on the catalyst surface. [ABSTRACT FROM AUTHOR]

The passive ammonia SCR system has been considered as a novel after-treatment method to reduce the emission of NOx and produce ammonia for downstream SCR. A series of Pd0.01FexCe(1−x)/2Zr(1−x)/2Oy catalysts (x = 0, 0.1, 0.2, and 0.4) was synthesized through a solution combustion synthesis (SHS) method. Their catalytic activities were investigated by XRD, BET, Raman, H2-TPR, XPS, and in situ DRIFTS. The relationship between the reactivity and species composition, acidic properties, surface oxygen vacancies, and redox behavior of the Pd0.01FexCe(1−x)/2Zr(1−x)/2Oy catalysts was established. Results demonstrated that a moderate amount of Fe doping can markedly enhance the specific surface area, improve the surface oxygen vacancies, increase the surface acidic sites, and tune the valence distribution of surface elements. Pd0.01Fe0.1Ce0.45Zr0.45Ox showed the highest ammonia yield with a wide reaction-temperature window (250–400 °C) and >95% NO conversion and complete conversion from nitric oxide to ammonia at 300–400 °C. This may be due to the phenomenon that highly dispersed Fe2O3 enhanced the interaction among PdO, Fe2O3 and the Ce0.5Zr0.5O2 support, improved the displacement of active species on the catalyst surface, and increased the surface oxygen vacancies, thus improving the catalytic activity. [ABSTRACT FROM AUTHOR]

This study concentrates on improving the low temperature performance of CDPF catalysts. The self-propagating high temperature combustion synthesis method was applied to synthesize a series of CeZrO 2- δ , CuCeZrO 2- δ , and MnCuCeZrO 2- δ catalysts, which were coated on DPF substrate. The performance of the catalysts was fully investigated by the soot temperature programmed combustion, which showed that these catalysts with nanometer size have a high catalytic activity of soot combustion at low temperatures. Compared with Ce 0.05 Zr 0.05 O 2- δ , Cu 0.9 Ce 0.05 Zr 0.05 O 2- δ and Mn 0.09 Cu 0.81 Ce 0.05 Zr 0.05 O 2- δ showed excellent low temperature soot oxidation activities and much higher CO 2 selectivity. BET, XRD, TEM, and XPS were employed to characterize the structural and physical-chemical properties of catalysts. The XRD results indicated that catalysts with 90% Cu possess evenly distributed crystalline grains and small particle size, which is responsible for its excellent oxidation activity by providing more active sites as well as forming good connection between the catalyst and soot. The XPS results demonstrated that the Cu x + has a significant association with the formation of NO 2 , thus promoting the soot oxidation, and that the synergetic effect between Cu x + and Mn x + contributes most to the improvement of the catalytic activity. The partial substitution with Mn could enhance the chemisorbed oxygen, which further improved NO oxidation and CO 2 selectivity. Furthermore, the soot combustion reaction mechanism was examined with in situ DRIFTS. The results exhibited that the active sites of Cu 0.9 Ce 0.05 Zr 0.05 O 2- δ and Mn 0.09 Cu 0.81 Ce 0.05 Zr 0.05 O 2- δ could generate more reactive oxygen for NO oxidation and that the uniformly dispersed Cu x + and Mn x + in Ce lattice could adsorb NO 2 to form nitrite and nitrates, which behaved as a carrier of NO 2 and transported it around the surface of soot, thus facilitating the soot combustion, especially at low temperatures. [ABSTRACT FROM AUTHOR]

Under nitrogen atmosphere, a simple and efficient procedure for the synthesis of symmetrical selenides has been developed by the reaction of aryl or alkyl halides with magnesium (1.5 equiv) and elemental selenium (1.0 equiv) in the absence of catalyst and ligand in THF and toluene under reflux at 86°C. This protocol has been utilized for the synthesis of a variety of symmetrical selenides in good to excellent yields. [ABSTRACT FROM AUTHOR]

Abstract: This study addresses soot oxidation and NO x reduction over a BaAl2O4 catalyst. By XRD analysis, the catalyst was shown to be of spinel structure. Temperature Programmed Oxidation (TPO) and Constant Temperature Oxidation (CTO) at 673K show that the presence of O2 decreases the ignition temperature of soot, and it enhances the conversion of NO x to N2 and N2O. The kinetic features of soot oxidation in the TPO test are similar to that in the TG–DTA analysis. Analysis by Diffuse Reflectance Fourier Infrared Transform Spectroscopy (DRIFTS) indicates that the nitrates formed from NO x adsorption and the C(O) intermediates from soot oxidation are the key precursors of the redox process between soot and NO x over surfaces of the BaAl2O4 catalyst. Moreover, DRIFTS tests suggest that nitrates act as the principal oxidants for C(O) oxidation, through which nitrates are reduced to N2 and N2O. The O2 in the gas mixture presents a positive effect on the conversion of NO x to N2 and N2O by promoting the oxidation of nitrites into nitrates species. [Copyright &y& Elsevier]

The interactions between NO, O2 and their mixture on BaAl2O4, as well as the reaction of NOx with soot in the presence of O2, have been investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). NO adsorption produces only nitrites species in the absence of O2. NO2 adsorption produces nitrates species besides nitrites species. The produced nitrites will further react with O2, Osurf- and Olattice2- to form nitrates. The reaction of NOx with soot begins with the reaction of nitrates with soot oxygenated complex (C(O)), which is regarded as the key and rate determining step. A reaction pathway is proposed for the catalyzed reaction of NOx with soot in the presence of O2. [ABSTRACT FROM AUTHOR]

The interactions between NO, O2 and their mixture on BaAl2O4, as well as the reaction of NOx with soot in the presence of O2, have been investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). NO adsorption produces only nitrites species in the absence of O2. NO2 adsorption produces nitrates species besides nitrites species. The produced nitrites will further react with O2, Osurf- and Olattice2- to form nitrates. The reaction of NOx with soot begins with the reaction of nitrates with soot oxygenated complex (C(O)), which is regarded as the key and rate determining step. A reaction pathway is proposed for the catalyzed reaction of NOx with soot in the presence of O2. [ABSTRACT FROM AUTHOR]

Abstract: A highly efficient and porous catalyst (La0.8K0.2Cu0.05Mn0.95O3) for simultaneous removal of nitrogen oxides (NOx) and diesel soot was synthesized and the sample was characterized by XRD, BET, SEM–EDS, XRF, and XPS. The results indicate that this catalyst is perovskite and it possesses the very good characteristics for multiphase catalytic reactions. The catalytic properties were appraised under simulated diesel engine exhaust by temperature programmed reaction (TPR). TPR results indicate that this catalyst is a promising candidate for simultaneous removal of NOx and diesel soot. The maximum NO conversion into N2 and the ignition temperature of soot are 54.8% and 260°C, respectively. Comparing with those in previous reports, the comprehensive performance of this catalyst is greatly improved by partial substitution of La with K and Mn with Cu at the same time. [Copyright &y& Elsevier]

The simultaneous removal of NOx and particulate matter (PM) from diesel exhaust is investigated over a mixed metal oxide catalyst of La_{0.9}K_{0.1}CoO_3 loaded on γ-Al_2O_3 spherules with the assistant of plasma. It was found that NOx was reduced by PM in oxygen rich atmosphere, the CO_2 and N_2 were produced in the same temperature window without considering the N_2 formed by plasma decomposition. As a result, the temperature for the PM combustion decreases and the reduction efficiency of NOx to N_2 increases during the plasma process, which indicated that the activity of the catalyst can be improved by plasma. The NOx is decomposed by plasma at both low temperature and high temperature. Therefore, the whole efficiency of NOx conversion is enhanced. [ABSTRACT FROM AUTHOR]

A new heterogeneous catalytic transfer hydrogenation (CTH) system, consisting of a non-flammable supported Au catalyst along with 2-propanol as the hydrogen donor, was proven to be effective for chemoselective reduction of a wide range of aromatic ketones and aldehydes to the corresponding alcohols. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbenes (NHCs) prove to be efficient catalysts for the aza-Morita-Baylis-Hiliman (aza-MBH) reaction of cyclopent-2-en-1-one or cyclohex-2-en-1-one with a variety of N-tosylarylimines to give the aza-MBH adduct in high yields. Crossover experiments show NHC can add to N-tosylarylimines in a reversible manner, which allows the addition of NHC to cyclic enones and thus catalyzes the aza-Mortia-Baylis-Hiliman reaction. [ABSTRACT FROM AUTHOR]

The application of electric field promotes benzene oxidation significantly over Pd/CoxCey catalysts. For 1% Pd loading catalysts, the complete oxidation of benzene can be realized at 175 °C with an electric field under an input current of 3 mA, 79 °C lower than the temperature demanded for complete benzene conversion without electric field. The introduction of electric field can save Pd loading in the catalysts while maintaining high benzene conversion. The characterization experiments showed that CeO2 reduction was accelerated with electric field and created more active oxygen, promoting the formation of active sites on the catalyst surface. The OH removal ability of PdO was enhanced by forming CoO(OH) species, which can easily dehydroxylate since the reduction of Co3+ was promoted by the electric field. The optimized Ce/Co ratio is a balance between oxygen availability and OH removal ability. [ABSTRACT FROM AUTHOR]

Cu/CHA and sodium-promoted Cu/CHA catalysts were prepared and applied to catalyze NH 3 -SCR reaction. Also, the effect of phosphorus poisoning on the catalytic performance of these two catalysts were explored. Compared with Cu/CHA catalyst, sodium-promoted Cu/CHA catalyst presented better catalytic performance, which was attributed to the optimized distribution of copper active sites. Moreover, it was proved that sodium ions as sacrificial sites could effectively protect copper active ions and improve the phosphorus poisoning resistance of the sodium-promoted Cu/CHA catalyst. [Display omitted] • CuCHA and sodium-promoted Cu/CHA catalysts were synthesized. • Sodium-promoted Cu/CHA catalyst presented better catalytic performance. • The phosphorus poisoning resistance of sodium-promoted Cu/CHA catalyst was improved. • Sodium ions acted as sacrificial sites to protect copper active sites. [ABSTRACT FROM AUTHOR]

• Selective catalytic reduction of NO x with NH 3 over Cu/SSZ-13. • Catalysts are prepared by one-pot synthesis method with different Si/Al ratios. • Cu/SSZ-13-6.5 shows the best NH 3 -SCR performance and hydrothermal stability. • Increasing Si/Al deteriorates physical-chemical properties of aged catalysts. • Increasing Si/Al decreases active sites, nitrate species, acidity of aged catalysts. This study focuses on investigating the influence of Si/Al ratio on the performance of hydrothermally aged Cu/SSZ-13 catalysts prepared by in situ hydrothermal synthesis method. It was found that NH 3 -SCR performance and hydrothermal stability of Cu/SSZ-13 decreased with increasing Si/Al ratio. Fresh and hydrothermally aged Cu/SSZ-13 with Si/Al ratio of 6.5 showed the best SCR activity and N 2 selectivity in a broad temperature of 200–500 °C, in which more than 90% NO x was reduced with superior N 2 selectivity above 95%. The effect of Si/Al ratio on the properties of the physicochemical structure, the change of acidity intensity, and Cu species migration or transformation of the fresh and aged Cu/SSZ-13 catalysts were comprehensively characterized by NH 3 -TPO, NH 3 -TPD, H 2 -TPR, N 2 physisorption, XRD, ICP-AES, and XPS. The increase of the surface CuO species, the decrease of the amount of Cu2+ in active sites, the chemisorption NH 3 species, the specific surface area, the total pore volume, and the increase of average pore diameter, may be the main reasons for performance deterioration over high-Si/Al-ratio catalysts after hydrothermal aging. Furthermore, in situ DRIFTS indicate that, with the increasing Si/Al ratio, the zeolitic structure was easy to collapse, and that the surface acid sites, the active copper species, as well as the adsorbed surface nitrate, decreased after hydrothermally aged. After hydrothermal aging, the amount of isolated Cu2+ decreased, and more CuO species were aggregated, mainly coming from the conversion of the unstable isolated Cu2+ species in D6R or CHA cages. The decrease of isolated Cu2+ and CuO species aggregation were significant in Cu/SSZ-13 with high Si/Al ratios. The CuO leaded to the instability of the SSZ-13 skeleton structure and NH 3 oxidation promotion, resulting in catalysts deactivation. [ABSTRACT FROM AUTHOR]

• The ammonia decomposition activity of A/Ce x Zr 1-x O 2 (A = Ni or Co, Fe) catalysts are analyzed. • The ammonia decomposition activity is improved effectively with electric field assistance. • Ni-based catalysts have the highest activity, while Fe-based catalyst had the highest energy efficiency with electric field. • The synergistic effects of basicity enhancement and proton hopping increase the activity of catalysts. It is a good strategy to improve the combustion performance of ammonia in engines by onboard hydrogen mixing through ammonia decomposition. To utilize the exhaust heat from engines, a novel technology to decompose ammonia at low temperature (<350 °C) was studied, which is based on the synergistic effect between electric field and Ce-doped catalysts. A series of non-noble metals (Fe/Co/Ni) supported on Ce-doped ZrO 2 semiconductor (Ce x Zr 1-x O 2) were synthesized by solution combustion method to investigate the electric field-assisted catalytic activity. We achieved an ammonia conversion of 60% at 300 °C for Ni/Ce 0.25 Zr 0.75 O 2 catalyst and the maximum energy efficiency is close to 20% for Fe/Ce 0.25 Zr 0.75 O 2 catalyst with electric field. The synergistic effects of basicity enhancement and proton hopping between the electric field and Ce-doped catalysts were found by a series of characterizations. Electric field facilitated the generation of strong basic sites, which was beneficial to the recombinative desorption of nitrogen. And the proton hopping helped to reduce hydrogen poisoning. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Lean methane oxidation at 250 °C was realized in the electric field. • More oxygen species formed from the reduction of Ce4+ → Ce3+ in the electric field. • The electric field reinforced Co2+ oxidation and formation of highly active Co3+. • Chemisorption CH 4 at low temperature follow M-K mechanism in the electric field. • A new mechanism of catalytic oxidation of CH 4 in electric field was proposed. Abstract Electric field was introduced for ultra-lean methane oxidation over a series of Co 3 O 4 /Ce 0.75 Zr 0.25 catalysts. Catalytic activities were significantly promoted by the electric field. It was found that the catalyst with 25% of Co loading showed the highest catalytic activity at 9 mA of electric currency, and the light-off temperature (T 50) was as low as 240 °C. The effect of the electric field over the catalysts was examined from the structural and surface point of view (XRD, XRS, BET, H 2 -TPR). The obtained results demonstrated that the electric field facilitated the release of oxygen from lattice by promoting the reduction of Ce4+ to Ce3+, therefore reinforced the formation of Co 3 O 4 on catalyst surface. Moreover, tetrahedral Co2+ in the Co 3 O 4 spinel were oxidized to Co3+. Besides, electric field enhanced the reducing capacity of the Co 3 O 4 with the newly formed tetrahedral Co3+ easily reduced at low-temperature conditions. The FTIR results revealed that the active sites of methane chemisorption located respectively at tetrahedral Co3+ with active O species from lattice in the electric field, and octahedral Co3+ with pre-adsorbed gaseous O 2 formed at relatively higher-temperature in conventional catalytic process. The following dehydrogenation and oxidation processes were accelerated in the electric field with fast conversion rates of intermediates, namely methyl and formates species. Based on experimental results and comprehensive analysis, the mechanism of catalytic oxidation of methane over Co 3 O 4 /Ce 0.75 Zr 0.25 catalysts with the assistance of electric field was proposed. [ABSTRACT FROM AUTHOR]

Metal-organic framework (MOF)-derived transition metal/metal oxide-carbon hybrids are promising cost-effective electrocatalysts to replace noble metal catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Co@CoO@Co 3 O 4 -N/C was prepared by two-step thermal treatment of Co-MOF ([Co(INA) 2 ]·0.5EtOH) (INA: isonicotinic acid). Firstly, Co-MOF, as precursor, was pyrolyzed at different temperatures in N 2 atmosphere to obtain Co-N/C-T (T = 700, 800, 900 °C) materials among which Co-N/C-800 shows remarkably high ORR activity. After oxidation treatment, Co-N/C-800 is transformed into Co@CoO@Co 3 O 4 -N/C which exhibits enhanced electrocatalytic activities for both ORR and OER. The as-obtained Co@CoO@Co 3 O 4 -N/C has more positive onset potential (−0.136 V vs. Ag/AgCl) and higher limit current density (4.9 mA cm −2 ) than Co-N/C-800 (−0.143 V vs. Ag/AgCl and 3.9 mA cm −2 ), as well as better tolerance to methanol and stability (80.0%) than those of Pt/C (63.2%) for ORR. Co@CoO@Co 3 O 4 -N/C also displays outstanding OER performances, with lower overpotential (450 mV) than that of Co-N/C-800 (492 mV) at a current density of 10 mA cm −2 . The excellent electrochemical performance of Co@CoO@Co 3 O 4 -N/C can be ascribed to uniformly dispersed Co-N x active sites, strong synergistic effects between N-doped carbon support and Co@CoO@Co 3 O 4 as well as ordered mesoporous structure, boosting mass transfer and accelerating electrocatalytic reaction. [ABSTRACT FROM AUTHOR]

• Exploring the effects of Si/Al ratio and Cu/Al ratio on catalyst activity. • Researching the sensitivity of catalyst to aging time and aging temperature. • Explaining the reasons for the degradation of catalyst performance caused by hydrothermal aging. • Using in-situ DRIFTS experiments and DFT molecular simulation calculations to explore the mechanism. • Completing the hydrothermal aging mechanism of Cu-SSZ-13 small pore molecular sieve catalyst. A series of Cu-SSZ-13 small-pore molecular sieve catalysts are prepared by the ion-exchange method, analyzed, and tested by changing the synthesis ratio, and performing hydrothermal aging treatment under various aging conditions to explain the degree of influence. The investigations are carried out to reveal that when the Si/Al ratio is 10, the catalyst has the best comprehensive performance and ZCuOH sites are more prone to transformation and loss than Z 2 Cu sites during the hydrothermal aging process. In-situ DRIFTS experiments and DFT molecular simulation calculations are used to explain the reasons for the degradation of catalytic performance caused by the hydrothermal aging, which completes the study of the hydrothermal aging mechanism for Cu-SSZ-13 molecular sieve catalysts. The result shows that Z 2 Cu active sites exhibit better hydrothermal aging resistance than ZCuOH, the catalyst is more sensitive to aging temperatures than durations, and its limit of the aging temperature is about 850 ℃. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electric field greatly improves the water resistance of PCZA-3/2-F catalyst. • Electric field inhibits the aggregation of surface hydroxyl palladium. • Electric field causes strong metal-support interaction at low temperature. • The inhibited hydroxy palladium is activated in electric field. Methane (CH 4) is an important greenhouse gas, and its ability to cause greenhouse effect is 25 times of the same amount of CO 2. Electric field is one of the effective ways to reduce the ignition temperature of CH 4 catalytic oxidation. In this paper, a Pd-based catalyst with Ce 0.75 Zr 0.25 -γ-Al 2 O 3 composite support was synthesized by impregnation and its activity and water resistance were evaluated. The effect of water and electric field on the properties of catalyst was investigated by XRD, XPS, BET, TEM, H 2 -TPR and in-situ DRIFT. The results showed high CH 4 conversion was maintained in the presence of water because the aggregation of Pd specie was prevented by electric field. After 24 h operation in electric field, catalyst's lattice structure remained stable, however, a loss of surface Pd active sites due to the strong metal-support interaction and the formation of Pd-OH were observed, and finally reduced its thermal activity. Pd-OH, the inhibited site in thermal reaction, can be used as active site to participate in CH 4 oxidation process, which was the key factor in maintaining high activity of the catalyst in electric field. [ABSTRACT FROM AUTHOR]

• The CuO x @SiO 2 catalyst with excellent performance by the FSP method. • The CuO x @SiO 2 catalyst has good thermal stability due to strong sintering resistance. • Catalytic ammonia oxidation over the CuO x @SiO 2 catalyst follows fast i-SCR mechanism. • Reaction path at low temperature is different from that at high temperature. Ammonia has a great application prospect to reach zero-carbon emissions in the combustion society. However, the poor ignition and combustion performance and NOx emissions of ammonia limit its utilization, and catalytic combustion may be a reliable way to utilize ammonia. In this study, the catalysts were prepared by the flame spray pyrolysis method (FSP), and the catalytic combustion performance of ammonia was investigated in a wide temperature range (100–1000 °C). The results indicated that CuO x and core–shell CuO x @SiO 2 had high catalytic activity and N 2 selectivity under different equivalence ratios compared with other catalysts (FeO x and MnO x), and the thermal stability of CuO x @SiO 2 were more prominent. These two catalysts before and after ammonia catalytic combustion tests were characterized to reveal their acting mechanism. At low temperature (<600 °C), the catalytic ammonia combustion over CuO x followed the internal-selective catalytic reduction (i-SCR) mechanism, while that on CuO x @SiO 2 followed the fast i-SCR mechanism, resulting in the outstanding N 2 selectivity of CuO x @SiO 2. At high temperature (600–1000 °C), CuO x @SiO 2 with a better thermal stability hardly sintered. Hydrogen was generated at high temperature and then reacted with oxygen under low equivalence ratio or with the lattice oxygen of the fresh catalyst under high equivalence ratio. The core–shell CuO x @SiO 2 catalyst synthesized by the FSP method provides a novel idea on the catalyst design for catalytic ammonia combustion. [ABSTRACT FROM AUTHOR]

• The addition of fuel reforming gas simultaneously reduced NO X and HC emissions from natural gas engines. • CO emissions showed a trade-off to NOx and HC emission. • The addition of fuel reforming gas showed no damage of economic performance of the engine. • A promising on-board fuel reforming scheme for vehicles was proposed. Combustion, emission characteristics and the economic performance of a heavy-duty natural gas engine blended with different ratios of reformed gas were investigated, and the feasibility of applying the fuel partial oxidation catalytic reforming system on a heavy-duty natural gas engine was discussed. Experimental results showed that the use of Rh/γ-Al 2 O 3 as a catalyst of partial oxidation reaction of natural gas fuel requires low initial reaction inlet gas temperature, and it has good catalytic performance and durability, which makes it feasible to be applied on vehicles. Blending with reformed gas from partial oxidation reaction significantly reduces NO X and CH 4 emission and effectively reduces coefficient of variance of peak pressure. In additions, no significant change in fuel consumption was observed after blending with reformed gas, while CO emissions increased. In general, the combination of on-board fuel partial oxidation catalytic reforming system to improve the performance of natural gas engines has good prospects. [ABSTRACT FROM AUTHOR]

• Electric field induces Ce-TiO 2 (Ce/Ti≤0.2) transition from anatase to rutile. • Amorphous Ce-Ti structure can remain stable in electric field. • Electric field induces reduction of Pd2+ to Pd0. • Catalyst with Ce/Ti = 0.1 showed higher catalytic activity in electric field. Electric field assisted catalysis is regarded as an emerging approach for methane catalytic oxidation in recent years. In this paper, the catalytic performance of Pd/Ce-Ti nano-catalyst for methane oxidation in an electric field was evaluated. We found appropriate Ce doping with TiO 2 lattice structure are beneficial to enhance the catalytic activity (Catalyst with Ce/Ti = 0.1 has 90% CH 4 conversion at 256 ℃ with 3 mA current, 30,000 mL·g−1·h−1). XRD, Raman, BET, TEM, XPS and H 2 -TPR were used to study the surface properties and structure changes of the catalyst in electric field. It was found metallic Pd0 generation on surface is beneficial to improve the reaction activity and electric field could promote the reduction of Pd2+ to Pd0. For Ce-Ti solid solution, electric field can induce the transformation from anatase to rutile. During the dynamic lattice phase transition, catalytic activity increased significantly in a short time, but the CH 4 conversion decreased gradually as the structure became stable. In addition, Ce-Ti amorphous structure has better stability in an electric field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow nanospheres surrounded by small nanoparticles shows better CH 4 conversion. • Catalyst obtained by FSP method has more surface oxygen vacancies and hydroxyl groups. • There is a synergistic effect between the electric field and the catalyst. A kind of Pd 0.01 Ce 0.75 Zr 0.25 O 2 hollow nanospheres surrounded by small nanoparticles prepared by flame spray pyrolysis (FSP) method (Pd 0.01 Ce 0.75 Zr 0.25 O 2 -F) were used for methane oxidation in electric field. Compared with the samples synthesized by solution combustion method, more Pd active sites is exposed to Pd 0.01 Ce 0.75 Zr 0.25 O 2 -F catalyst surface and it shows higher redox performance. The methane conversion over Pd 0.01 Ce 0.75 Zr 0.25 O 2 -F is higher (T 50 = 320 °C in 5 mA electric field, GHSV = 50,000 ml·g−1·h−1), and the turnover frequency (TOF) is significantly increased (ΔTOF = 4.33 × 10-4 × s−1) under the effect of electric field. There is a strong interaction between electric field and Ce-Zr metastable structure, which is due to the higher content of surface hydroxyl groups on Pd 0.01 Ce 0.75 Zr 0.25 O 2 -F surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 3 -SCR reaction over pure and Ce modified Cu/SAPO-34. • CuCe/SAPO-34 showed better catalytic performance and low temperature hydrothermal stability. • Co-cation Ce improved the formation of active copper sites. • The formation of Si-O(Ce)-Al bond limited the dealumination process. • Ce doping led to the more monodentate nitrates adsorbed sites formed. This study focuses on co-cations modified copper based molecular sieve catalyst CuCe/SAPO-34. The SCR performance and low temperature hydrothermal stability of Cu/SAPO-34 and CuCe/SAPO-34 before and after 70 ℃ hydrothermal aging were evaluated to conclude the impact of Ce on the structure stability and mechanism of NH 3 -SCR reaction. For fresh samples, CuCe/SAPO-34 showed higher catalytic activity at the whole temperature range, especially below 250 ℃ and above 400 ℃ in comparison to pure Cu/SAPO-34. For aged catalysts, CuCe/SAPO-34 exhibited higher efficiency at below 400 ℃ than Cu/SAPO-34, and showed more than 80 % NO x conversion at 175 ℃ to 450 ℃ , whereas, that was only 225 ℃ to 450 ℃ for Cu/SAPO-34. The effect of co-cation Ce on the physicochemical structure, acidity, redox capacity, Cu species migration, and framework stability of the fresh and aged samples were comprehensively characterized by NH 3 -TPO, NO-TPO, H 2 -TPR, NH 3 -TPD, BET, XRD and XPS. For the fresh samples, the addition of co-cation Ce decreased the amount of Cu x O y species, increased Cu2+ sites, and improve the redox ability of active sites. After low temperature hydrothermal aging, CuCe/SAPO-34 remained the structural integrity of CHA framework. Ce species protected copper ions and prevented the dealumination in the process of aging. Furthermore, in situ DRIFTS indicated that, with the Ce doping, more active copper sites and monodentate nitrates adsorbed sites formed, resulting in excellent SCR performance and stability. In conclusion, modification by Ce could improve the SCR performance and low temperature hydrothermal stability of Cu/SAPO-34 catalyst. [ABSTRACT FROM AUTHOR]

• The impact of sulfur poisoning and regeneration on Cu/SSZ-13. • Regeneration could not totally recover the efficiency of sulfured catalysts. • Different sulfate species formed on the main active sites of Cu/SSZ-13. • SO 2 was oxidized by Cu x O y species, and Si-O(H)-Al bond could not be poisoned without active metal species. • Active sites and nitrates/nitrites storage capacity decreased after sulfur poisoning. This study focuses on exploring the impact of sulfur poisoning and regeneration on the performance and active sites of Cu/SSZ-13 catalyst. It was found that sulfured samples had obviously lower conversion than fresh samples below 350 °C, and thermal regeneration at 550 °C could not totally remove sulfate species. These catalysts were also comprehensively characterized by H 2 -TPR, TPD, NH 3 -TPO, NO-TPO, and BET. SO 2 and NH 3 co-adsorbed on the Z 2 Cu sites to form ammonia sulfate species, however, they went through the two-step decomposition reaction during regeneration. SO 2 interacted more tightly with ZCuOH to form copper bisulfite species. SO 2 was oxidized by Cu x O y species to further form sulfate species. Si-O(H)-Al bond could be sulfur poisoned when Cu species in the catalysts. Additionally, sulfated species could block pores, but not lead to structure collapse. Furthermore, in situ DRIFTS results illustrated that active sites and nitrates/nitrites storage capacity decreased after sulfur poisoning. [ABSTRACT FROM AUTHOR]