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CoCu-based catalysts are widely used in COx hydrogenation reactions to produce higher alcohols due to the C-C coupling ability of Co and the ability of Cu to produce alcohols. This work describes the role of easily happened CO2 dissociation on the CoCu surface during the reaction, using different silica support to tune the metal—support interaction, and reaches different selectivity to ethanol. CoCu supported on mesoporous silica MCM-41 shows ethanol selectivity as high as 85.3%, and the ethanol space-time yield (STY) is 0.229 mmol/(gmetal·h), however, poor selectivity to ethanol as low as 28.8% is observed on CoCu supported on amorphous silica. The different selectivity is due to the different intensities of CO2 dissociation on the catalysts. The adsorbed O⋆ produced via CO2 dissociation can occupy the cobalt hollow sites on CoCu surfaces, which are also the adsorption sites of C1 intermediates for further C-C coupling. [ABSTRACT FROM AUTHOR]

The synergy between metals and metal oxides can effectively improve the heterogeneous catalytic process. This paper describes the intrinsic effect of Pt modification over GaOx (Pt−GaOx) on propane dehydrogenation. The presence of Pt promotes H2 dissociation and surface coverage of hydrogen species, which is beneficial for the activation of C−H in propane. With excessive Pt, Gaδ+ can be further reduced to form Pt−Ga alloy with less surface hydrogen species. Consequently, the relative propylene formation rate between Pt−GaOx and the summed contribution of individual Pt and GaOx increases linearly with the content of hydrogen species. Optimally, the relative propylene formation rate of Pt−GaOx with 0.03 wt % Pt exceeds 25 % of the summed contribution of individual components. [ABSTRACT FROM AUTHOR]

Cobalt‐copper (CoCu) catalysts have industrial potential in CO/CO2 hydrogenation reactions, and CoCu alloy has been elucidated as a major active phase during reactions. However, due to elemental surface segregation and dealloying phenomena, the actual surface morphology of CoCu alloy is still unclear. Combining theory and experiment, the dual effect of surface segregation and varied CO coverage over the CoCu(111) surface on the reactivity in CO2 hydrogenation reactions is explored. The relationship between C−O bond scission and further hydrogenation of intermediate *CH2O was discovered to be a key step to promote ethanol production. The theoretical investigation suggests that moderate Co segregation provides a suitable surface Co ensemble with lateral interactions of co‐adsorbed *CO, leading to promoted selectivity to ethanol, in agreement with theory‐inspired experiments. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) with atomically dispersed metals have emerged as a new class of heterogeneous catalysts and have attracted considerable interest because they offer 100% metal atom utilization and show excellent catalytic behavior compared with traditionally supported nano-particles. However, it is challenging to explore the active sites and catalytic mechanisms of SACs through common characterization methods due to the isolated single atoms. Therefore, employing theoretical calculations to determine the nature of SACs' active sites and the reaction mechanisms is particularly meaningful. This paper describes the nature of SACs by summarizing the diverse applications and properties of SACs, which starts from computational simulation on a couple of important applications of SACs. Then the distinctive and fundamental properties of SACs are discussed. At last, the challenges and future perspectives of computational calculations for SACs are outlined. [ABSTRACT FROM AUTHOR]

Catalytic conversion of CO2 to produce fuels and chemicals is attractive in prospect because it provides an alternative to fossil feedstocks and the benefit of converting and cycling the greenhouse gas CO2 on a large scale. In today's technology, CO2 is converted into hydrocarbon fuels in Fischer–Tropsch synthesis via the water gas shift reaction, but processes for direct conversion of CO2 to fuels and chemicals such as methane, methanol, and C2+ hydrocarbons or syngas are still far from large-scale applications because of processing challenges that may be best addressed by the discovery of improved catalysts—those with enhanced activity, selectivity, and stability. Core–shell structured catalysts are a relatively new class of nanomaterials that allow a controlled integration of the functions of complementary materials with optimised compositions and morphologies. For CO2 conversion, core–shell catalysts can provide distinctive advantages by addressing challenges such as catalyst sintering and activity loss in CO2 reforming processes, insufficient product selectivity in thermocatalytic CO2 hydrogenation, and low efficiency and selectivity in photocatalytic and electrocatalytic CO2 hydrogenation. In the preceding decade, substantial progress has been made in the synthesis, characterization, and evaluation of core–shell catalysts for such potential applications. Nonetheless, challenges remain in the discovery of inexpensive, robust, regenerable catalysts in this class. This review provides an in-depth assessment of these materials for the thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2 into synthesis gas and valuable hydrocarbons. [ABSTRACT FROM AUTHOR]

This communication describes an efficient co-catalyst Co3O4 nanoparticle with a tunable two-electron water oxidation reaction pathway in photoelectrochemical H2O2 production. The photoluminescence measurement explains that the promotion effect is due to the accelerated activation of water to ṖOH. The increased Faraday efficiency of H2O2 for the Co3O4/WO3 sample also verifies that the promotion effect to a two-electron water oxidation reaction of Co3O4 is universal to other semiconductor photoanodes. [ABSTRACT FROM AUTHOR]

Abstract: Carbon dioxide (CO2) reduction in aqueous solutions is an attractive strategy for carbon capture and utilization. Cuprous oxide (Cu2O) is a promising catalyst for CO2 reduction as it can convert CO2 into valuable hydrocarbons and suppress the side hydrogen evolution reaction (HER). However, the nature of the active sites in Cu2O remains under debate because of the complex surface structure of Cu2O under reducing conditions, leading to limited guidance in designing improved Cu2O catalysts. This paper describes the functionality of surface‐bonded hydroxy groups on partially reduced Cu2O(111) for the CO2 reduction reaction (CO2RR) by combined density functional theory (DFT) calculations and experimental studies. We find that the surface hydroxy groups play a crucial role in the CO2RR and HER, and a moderate coverage of hydroxy groups is optimal for promotion of the CO2RR and suppression of the HER simultaneously. Electronic structure analysis indicates that the charge transfer from hydroxy groups to coordination‐unsaturated Cu (CuCUS) sites stabilizes surface‐adsorbed COOH*, which is a key intermediate during the CO2RR. Moreover, the CO2RR was evaluated over Cu2O octahedral catalysts with {111} facets and different surface coverages of hydroxy groups, which demonstrates that Cu2O octahedra with moderate coverage of hydroxy groups can indeed enhance the CO2RR and suppress the HER. [ABSTRACT FROM AUTHOR]

Abstract: Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and efforts have been made to improve its catalytic performance. However, unlike Pt‐based catalysts, the nature of the active site and surface structure of the supported vanadium catalysts under reductive reaction conditions still remain elusive. This paper describes the surface structure and the important role of surface‐bound hydroxyl groups on VOx / γ‐Al2O3 catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations. It is shown that hydroxyl groups on the VOx /Al2O3 catalyst (V−OH) are produced under H2 pre‐reduction, and the catalytic performance for PDH is closely connected to the concentration of V−OH species on the catalyst. The hydroxyl groups are found to improve the catalyst that leads to better stability by suppressing the coke deposition. [ABSTRACT FROM AUTHOR]

This paper describes catalytic consequencesThis paper describes catalytic consequences of Pt/CeO2-Al2O3 catalysts promoted with Ga species for propane dehydrogenation. A series of PtGa/CeO2-Al2O3 catalysts were prepared by a sequential impregnation method. The as-prepared catalysts were characterized employing N2 adsorption-desorption, X-ray diffrtaction, temperature programmed reduction, O2 volumetric chemisorption, H2-O2 titration, and transmission electron microscopy. We have shown that Ga3+ cations are incorporated into the cubic fluorite structure of CeO2, enhancing both lattice oxygen storage capacity and surface oxygen mobility. The enhanced reducibility of CeO2 is indicative of higher capability to eliminate the coke deposition and thus is beneficial to the improvement of catalytic stability. Density functional theory calculations confirm that the addition of Ga is prone to improve propylene desorption and greatly suppress deep dehydrogenation and the following coke formation. The catalytic performance shows a strong dependence on the content of Ga addition. The optimal loading content of Ga is 3 wt %, which results in the maximal propylene selectivity together with the best catalytic stability against coke accumulation. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4365-4376, 2016 [ABSTRACT FROM AUTHOR]

Efficient charge separation and light absorption are crucial for solar energy conversion over solid photocatalysts. This paper describes the construction of Pt@TiO2@In2O3@MnO x mesoporous hollow spheres (PTIM-MSs) for highly efficient photocatalytic oxidation. TiO2-In2O3 double-layered shells were selectively decorated with Pt nanoparticles and MnO x on the inner and outer surfaces, respectively. The spatially separated cocatalysts drive electrons and holes near the surface to flow in opposite directions, while the thin heterogeneous shell separates the charges generated in the bulk phase. The synergy between the thin heterojunctions and the spatially separated cocatalysts can simultaneously reduce bulk and surface/subsurface recombination. In2O3 also serves as a sensitizer to enhance light absorption. The PTIM-MSs exhibit high photocatalytic activity for both water and alcohol oxidation. [ABSTRACT FROM AUTHOR]

Au–Pd nanostructured materials have been recognized as important heterogeneous catalysts in various reactions, due to their superior activities caused by the ensemble and ligand effects. In recent years, shape-controlled synthesis of noble metal nanocrystals (NCs) provided a brand-new insight for improving the performance of catalysts. The electronic properties and catalytic activities of Au–Pd NCs could be optimized by tuning their shape and composition engineering. This review describes recent progress in the design and synthesis of shape-controlled Au–Pd bimetallic NCs and their emerging catalytic applications. The review starts with a general discussion of various applications of Au–Pd catalysts and the significance of preparing shape-controlled Au–Pd NCs, followed by an overview of synthetic strategies for two different structures of Au–Pd bimetallic catalysts: a core–shell structure and an alloy structure. We also put forward the key factors for the preparation of Au–Pd core–shell and alloy structures. Additionally, we discussed the unique optical properties and structural effects of shape-controlled Au–Pd NCs. These recent advancements in the methodology development of Au–Pd bimetallic NCs offer numerous insights for generating Au–Pd NCs with a number of unique geometries in the future. Furthermore, the systematic synthesis of core–shell or alloy structures would provide insights for the preparation of other bimetallic NCs. [ABSTRACT FROM AUTHOR]

The synthesis and application of bifunctional mesoporous Al-P-V-O catalysts with both acidic and redox sites for selective oxidation of methanol to dimethoxymethane (DMM) is described. The catalysts were characterized by N2 adsorption/desorption, X-ray diffraction, temperature-programmed desorption, X-ray photoelectron spectroscopy, and infrared spectroscopy. It is shown that porosity; redox property and surface acidity of the catalysts were greatly influenced by the Al/V/P ratio. The synergistic effect of phosphorus and vanadium was investigated. Al-P-V-O catalysts exhibited good catalytic activity because of the controlled reducibility and the acidic sites. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2587-2593, 2013 [ABSTRACT FROM AUTHOR]

The synthesis and utilization of an α-Mn2O3 nanocrystal catalyst for methanol-to-olefin reaction is described. A methanol conversion of 35% and a maximum selectivity of 80% toward ethylene were obtained at 250°C. In particular, formaldehyde, a primary intermediate for the reaction, was used to produce ethylene via a coupling reaction. A conversion of 45% and a selectivity of 66% to ethylene were achieved at 150°C in a formaldehyde stream. In situ diffuse reflectance infrared Fourier transform spectra reveal the formation of the surface CH2-containing species during reaction, which implies that the main pathway for formaldehyde coupling is probably through interactions of those intermediates. In addition, the weakly adsorbed oxygen on the α-Mn2O3 nanocrystal surface was found to play an important role in this reaction. © 2012 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

The design and application of a Cu/SiO2-based monolithic catalyst for hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG) is presented. The catalyst was dip-coated on cordierite with highly dispersed Cu/SiO2 slurry prepared by ammonia evaporation method. This structure guarantees high dispersion of copper species within the mesopores of silica matrix in the form of copper phyllosilicate. The catalyst is low cost, stable, and exhibits high activity in the reaction of hydrogenation of DMO, achieving a 100% conversion of DMO and more than 95% selectivity to EG. Notably, STYEG over the monolith is significantly enhanced compared to the packed bed Cu/SiO2 catalysts in both forms of pellet and cylinder. It is primarily due to the relatively short diffusive pathway of the thin wash-coat layer and high efficiency of the active phase derived from the monolithic catalyst. Theoretical results indicated that the internal mass transfer is dominated on the catalysts of pellet and cylinders. Moreover, the monolithic catalyst possessed excellent thermal stability compared to the pellet catalyst, which is attributed to the regular channel structure, uniform distribution of flow. © 2011 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

This article describes a strategy for increasing oxygen storage capacity (OSC) of ethanol steam reforming (ESR) catalysts. Sintering and carbon deposition are major defects of nickel-based catalysts for ESR; tuning oxygen mobility (OM) of CeO2-based supports can overcome these drawbacks and promote H2 production. We have successfully increased OSC and OM by adding Mg into the lattice of Ni/CeO2 to promote H2 production in ESR. The insertion of Mg into the CeO2 lattice efficiently promotes the reduction of Ce4+ according to X-ray powder diffraction (XRD) and temperature-programmed reduction (TPR) analysis. Mg-modified Ni/CeO2 catalysts have larger OSC and smaller nickel crystallite size compared with bare Ni/CeO2. The optimal Mg addition is 7 mol % (Ni/7MgCe) with the best OM. We also present evidence indicating that Mg addition significantly promotes ethanol conversion and H2 production in ESR, and that Ni/7MgCe yields the best performance due to the high OM of the support. These Mg-modified catalysts also produce less carbon deposition compared with Ni/CeO2, and the amount of deposited carbon decreases with increasing Mg addition. Ni/7MgCe has the best resistance to carbon deposition owing to the excellent OM. © 2011 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

Abstract: The transesterification of dimethyl oxalate (DMO) with phenol over stannum modified TS-1 was conducted to prepare methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), which could be used to produce diphenyl carbonate (DPC). The component, structure and phase of TS-1 catalysts with various Sn loadings were investigated. The relationship between the catalytic properties and the Sn loadings was discussed. The results indicated that, although the Sn-modified TS-1 catalysts had fewer Lewis acid sites than the unmodified TS-1, its catalytic activity was increased greatly by the interaction of Sn with Ti–O–SiO3 weak Lewis acid centers. The catalyst of TS-1 with 2 wt% Sn loadings performed best, giving 50.3% conversion of dimethyl oxalate and 99.2% selectivity to the target products. By means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX), the relationship between the catalytic properties and the structure of Sn dispersed on the surface of TS-1 was studied in detail. At Sn loadings below 2wt%, Sn was highly dispersed, but at higher loadings it was crystallized into bulk tin dioxide, where the interaction between Ti and Sn was not evidently observed, leading to decreased catalytic activity. XPS results showed that Ti could not be detected even at 1wt% Sn loadings. EDX results indicated that the content of Ti on the surface decreased with increasing Sn loadings, but the decrease in Ti content was much less than the increase in Sn content. Moreover, NH3-TPD and FTIR analyses of adsorbed pyridine showed that there were only weak Lewis acid centers on all catalysts and the Sn loadings hardly affected the acid strength of the catalysts. [Copyright &y& Elsevier]

Abstract: A new preparation method for supported MoO3 catalyst, slurry impregnation, has been described and compared with the conventional impregnation method. Slurry MoO3/water is used instead of the solution ammonium heptamolybdate, AHM [(NH4)6Mo7O24]. The MoO3/γ-alumina, MoO3/active carbon, and MoO3/silica catalysts with different Mo loadings were prepared by slurry and by conventional method. The low solubility of MoO3 was sufficient to transport molybdenum species from solid MoO3 to the adsorbed phase. The equilibrium was achieved after several hours at 95°C based on the loading amount of molybdenum. Only the process of drying was needed; calcination was not necessary and was left out. This is an important advantage for active carbon support because oxidative degradation of active carbon impregnated by molybdena starts at a relatively low temperature of about 250°C during calcination on air. The activity was tested in the transesterification of dimethyl oxalate (DMO) and phenol at 180°C. The dependences of catalytic activity on Mo loadings for the slurry prepared catalysts were similar to the dependences for the samples prepared by the conventional impregnation method with AHM. The activities of the slurry impregnation MoO3/γ-Al2O3 catalysts were almost the same as those of catalysts prepared conventionally. Although the performances of slurry impregnation MoO3/SiO2 catalysts for transesterification of DMO were slightly better than those of the corresponding catalysts prepared by conventional impregnation, no waste solution and no calcining nitrogenous gases were produced. Therefore, we conclude that the new slurry impregnation method for preparation of supported molybdenum catalysts is an environmentally friendly process and a simple, clean alternative to the conventional preparation using solutions of (NH4)6Mo7O24. The present work will lead to a remarkable improvement in the catalyst preparation for the transesterification reaction. [Copyright &y& Elsevier]

The transesterification of dimethyl oxalate (DMO) with phenol to methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO) was carried out in liquid phase under facile catalytic conditions. A series of bimetallic, MoO3–SnO2/SiO2, catalysts with various Mo and Sn content were prepared by sequential impregnation of cationic Mo species and cationic Sn complexes using impregnation method. The effects of mass ratio of Mo:Sn, amount of Sn additive, and Mo(Sn) laoding amount on activities of transesterification of dimethyl oxalate with phenol were investigated. The evaluation results showed that MoO3–SnO2/SiO2 catalyst with 14 wt% Mo(Sn) content performed best, giving 74.6% DMO conversion and 99.5% selectivity to MPO and DPO. This new heterogeneous catalyst provided not only an excellent selectivity (99% to MPO and DPO) and high yield of MPO and DPO but also a simple and practical protocol for DPC synthesis. [Copyright &y& Elsevier]

A series of MoO3/SiO2 catalysts were prepared with Mo loadings ranging from 1 to 16 wt% and applied to the transesterification of dimethyl oxalate (DMO) with phenol. The results showed that the catalyst of MoO3/SiO2 with 1 wt% Mo content performed best, giving 54.6% conversion of DMO and 99.6% selectivity to target products, methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO). The surface properties were investigated by means of X-ray diffraction (XRD), X-ray photoelectron (XPS), BET specific surface area, temperature-programmed desorption (TPD) of ammonia, and FTIR analysis of adsorbed pyridine. XPS and XRD analyses indicated that Mo(VI) species was highly dispersed at low Mo loading and MoO3 of the crystal structure appeared at higher loading. NH3-TPD characterization and FTIR analysis of adsorbed pyridine demonstrated that only Lewis weak acids were present on catalyst surface and the amount of Mo loading has little effect on the strength of the surface acid on MoO3/SiO2. The catalytic results exhibited that the synergetic effect of Mo active centers with weak Lewis acid sites catalyzed transesterification of DMO with phenol. [Copyright &y& Elsevier]

This communication describes the synthesis of Pt@CeO2 core–shell catalysts for the application of highly efficient CO oxidation, where the 50% CO conversion temperature is lower than 200 °C. Pt@CeO2 is thermally stable as no deactivation occurs during the 70 h reaction, and the morphology is unchanged even after 700 °C thermal treatment. [ABSTRACT FROM AUTHOR]

This communication describes the design of bifunctional VOx/TS-1 catalysts with enhanced redox and acidic character viadoping SO42−and PO43−for selective oxidation of methanol to dimethoxymethane. Redox sites enable the production of formaldehyde, while acidic sites favor the condensation of formaldehyde to DMM. [ABSTRACT FROM AUTHOR]

Catalytic conversion of CO2 to produce fuels and chemicals is attractive in prospect because it provides an alternative to fossil feedstocks and the benefit of converting and cycling the greenhouse gas CO2 on a large scale. In today's technology, CO2 is converted into hydrocarbon fuels in Fischer–Tropsch synthesis via the water gas shift reaction, but processes for direct conversion of CO2 to fuels and chemicals such as methane, methanol, and C2+ hydrocarbons or syngas are still far from large-scale applications because of processing challenges that may be best addressed by the discovery of improved catalysts—those with enhanced activity, selectivity, and stability. Core–shell structured catalysts are a relatively new class of nanomaterials that allow a controlled integration of the functions of complementary materials with optimised compositions and morphologies. For CO2 conversion, core–shell catalysts can provide distinctive advantages by addressing challenges such as catalyst sintering and activity loss in CO2 reforming processes, insufficient product selectivity in thermocatalytic CO2 hydrogenation, and low efficiency and selectivity in photocatalytic and electrocatalytic CO2 hydrogenation. In the preceding decade, substantial progress has been made in the synthesis, characterization, and evaluation of core–shell catalysts for such potential applications. Nonetheless, challenges remain in the discovery of inexpensive, robust, regenerable catalysts in this class. This review provides an in-depth assessment of these materials for the thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2 into synthesis gas and valuable hydrocarbons. [ABSTRACT FROM AUTHOR]

A correction to the article "Structure and Surface Chemistry of Gold-Based Model Catalysts" that was published in 2011 issue is presented.

[Display omitted] • The SMSI strength is adjusted by varying the pretreatment gas. • A more pronounced SMSI strength results in higher electron density of Pt. • The defective TiO x promotes C–H activation for enhancing activity. • Catalysts with stronger SMSI show better propane dehydrogenation performance. The strong metal-support interaction exerts a significant influence on the catalytic performance of the metal active site. This paper describes the modulation of the coverage of TiO x on the Pt nanoparticles via the pretreatment atmosphere, and its influence of the catalytic performance for propane dehydrogenation. The direct reduction in H 2 at 600 °C of the Pt/TiO 2 -Al 2 O 3 catalyst induces partial coverage of the Pt nanoparticles by TiO x. This partial coverage with TiO x leads to higher electron density over platinum than catalysts treated through air calcination followed by reduction, which can enhance the selectivity of propylene. Furthermore, the presence of TiO x in the catalysts can promote C–H activation during propane dehydrogenation. Eventually, this synergistic catalyst presents a high formation rate of propylene (141.1 mmol·g cat -1·h−1) and propylene selectivity of ∼ 91 % with a low deactivation rate of 0.09 h−1. This study unveils an effective approach to modulate the catalytic performance of metals supported on oxides based on metal-support interaction. [ABSTRACT FROM AUTHOR]

Various supported TiO2 catalysts, TiO2/SiO2, TiO2/Al2O3 and TiO2/MgO, were prepared by impregnation method and their activities in the transesterification of dimethyl oxalate (DMO) with phenol were tested. To further investigate the relationship between the catalyst performances and carrier properties, a series of characterization methods, such as BET specific surface area measurement, temperature-programmed desorption (NH3-TPD, CO2-TPD), and FT-IR analysis of adsorbed pyridine were utilized. The results indicated that the carrier had an important effect on the selectivities to products. The activities of supported TiO2 catalysts were improved significantly when TiO2 was supported on high surface area carriers. The weak acid sites were responsible for the formation of methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), while the intermediate acid sites and base sites were favorable for the formation of byproduct, anisole (AN). [Copyright &y& Elsevier]

The transesterification of dimethyl oxalate (DMO) with phenol over stannum modified Hβ was conducted to prepare diphenyl oxalate (DPO) used to produce diphenyl carbonate (DPC). The component, structure and phase of Hβ catalysts with various Sn loadings were investigated. The relationship between the catalytic properties and the amount of Sn loadings was discussed. The catalyst of Hβ with 2 wt.% Sn loading based on metal performed best, giving 75.3% conversion of DMO and 24.0% selectivity to DPO. At Sn loadings below 2 wt.%, Sn was highly dispersed as monolayer, but at higher loadings it was crystallized into bulk tin dioxide, and the catalytic activity decreased. The curve of XPS peak intensity ratio of Sn 3d/Si 2p versus Sn loadings estimated the dispersed capacity of Sn on Hβ to be 2.1% Sn loading, which was in good agreement with the value obtained from XRD analysis. NH3-TPD results showed that the amount of Sn loading had effect only on the strength of the weak surface acid sites on Hβ. And the decrease of selectivity to anisole was not due to the change of the weak acid sites. Maybe, SnO2 accelerated to the formation of MPO and DPO. FTIR analysis of adsorbed pyridine showed that many Lewis acid sites and few Brönsted acid sites were present on Hβ catalysts with or without Sn modified. The acid sites together with SnO2 active centers catalyzed the transesterification of DMO with phenol. Especially, SnO2 active centers were in favor of the disproportionation of MPO into DPO. [Copyright &y& Elsevier]

Review: 111 refs. [ABSTRACT FROM AUTHOR]

Process simulation of sorption enhanced chemical-looping reforming for hydrogen production from biomass was investigated. Corn stover was converted to bio-oil via pyrolysis prior to sorption enhanced chemical-looping reforming (SE-CLR). NiO was used as a catalyst and oxidizing agent and CaO was used as a CO 2 sorbent which are cycled between the reduction and oxidation reactors. Modification of the process to incorporate a step for catalyst and sorbent regeneration was examined and compared with conventional sorption enhanced chemical-looping reforming process. By modifying the SE-CLR process with the recirculating of solids from the air reactor directly to the reformer, a maximum bio-oil conversion rate of 92%, a maximum hydrogen production yield of 153.4 g H 2 /kg corn stover, and a maximum hydrogen purity of 77% v/v can be obtained with a circulated NiO to bio-oil molar ratio ( CNB ) of 12.3; a circulated CaO to bio-oil molar ratio ( CCB ) of 125.2; and where the ratio of solids recovered by the air reactor from the calcination reactor ( α ) was set as 1, and the ratio of solids flowing directly from the air reactor to the reformer ( β ) was set as 0.02. The split of a fraction of solids streams to feed directly back to the reformer offers a great impact process control as operating conditions can be broadened. [ABSTRACT FROM AUTHOR]

Sorption-enhanced steam reforming of ethanol shows potential of supplying high-quality hydrogen with in situ CO 2 capture, but suffers from sorbent deactivation. This paper describers the design of functionalized x NiO/Ca 9 Co 12 O 28 materials, whose phases can be segregated once triggered by the lattice oxygen consumption via NiO/Ca 9 Co 12 O 28 -O2-→Ni-Co+CaO, thus acting as the catalytic sorbent. Their superiorities are demonstrated in: (i) low-temperature activation via lattice oxygen induction; (ii) recyclability via lattice oxygen replenishment; iii) high-quality hydrogen actuation via in situ CO 2 adsorption. Hydrogen concentration of 95.56 vol% and near-complete ethanol conversion can be achieved. Moreover, stability across 50 repeated cycles without obvious reduction in catalytic reforming and CO 2 adsorption is demonstrated. In situ XRD studies demonstrate the formation of the Ni-Co alloy and the reorganization of the catalytic sorbent. The adsorption energies of ethanol on the surface of Ni(111), Co(111), and Ni-Co(111) were studied by DFT calculations, reaffirming the higher catalytic activity of Ni-Co alloys. [Display omitted] • A series of lattice oxygen triggered NiO/Ca 9 Co 12 O 28 catalysts were fabricated. • Phase segregation and reformation of the catalyst can be proceeded via switch-on-off looping. • Hydrogen concentration of 95.56 vol% and near 100% ethanol conversion can be achieved. • The promotional role of Ni doping on catalytic activity and CO 2 uptake capacity was identified. • DFT results revealed the enhancement of Ni-Co alloy on ethanol activation and CO 2 adsorption. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a catalytic reaction of hydrogen and carbon monoxide (Fischer–Tropsch synthesis (FTS)) over carbon nanotubes (CNTs) supported cobalt nanoparticles. We have investigated the effect of calcination of the catalysts on FTS performance using X-ray diffraction (XRD), H2 chemisorption, temperature programmed reduction (TPR), temperature programmed oxidation (TPO), and transmission electron microscopy (TEM) techniques. With the increase of outer diameter of CNTs, specific surface area of the catalyst decreases while Co particle size increased accompanying with a decrease in CO conversion. The FTS performance is similar for samples calcined in N2 or air at temperature below 550 °C. Over 550 °C, the results are much different in that the Co/CNTs can keep its activity due to the unchanged CNTs structure in N2 while the Co/CNTs almost lose activity owing to the loss of CNTs structure and sintering of cobalt oxide clusters in air. [Copyright &y& Elsevier]

• Cu-MgO/Al 2 O 3 bifunctional catalysts exhibit superior activity and stability in SESRM. • The incorporation of Cu2+ into MgO promotes CO 2 sorption and desorption capacity. • MgO facilitates the production of formate and consequent reduction of CO. • Cu sintering can be inhabited due to the strong interaction between Cu and MgO. Sorption enhanced steam reforming of methanol (SESRM) can significantly promote the hydrogen production process with simultaneous CO 2 sorption. The mechanical mixture of catalysts and sorbents as a conventional approach is complex and requires high temperatures for regeneration, which results in serious sintering of Cu-based catalysts. This paper describes a novel Cu-MgO/Al 2 O 3 bifunctional catalysts (x CMA, x is denoted as the mass fraction of Cu, 0%–10%) via a sol–gel method for the SESRM process. We find that Cu species, including metallic Cu and Cu ions, co-exist on the catalyst. The metallic Cu on the catalyst surface is an active site for methanol steam reforming while the Cu ion in MgO lattice promotes the CO 2 sorption capacity. Moreover, the incorporation of Cu ion into MgO also facilitates CO 2 desorption by forming more bidentate carbonates. Due to the strong interaction between Cu and MgO, the Cu sintering is inhabited in comparison with the mechanical mixture of catalysts and sorbents. Meanwhile, MgO is found to induce more formate species to inhibit the generation of carbon monoxide. As a result, the optimal bifunctional catalyst, 8 wt% Cu-MgO/Al 2 O 3 (8CMA) shows a superior performance in both catalytic reforming and CO 2 sorption with a highest H 2 selectivity of 99.3% and lowest CO selectivity (<0.15%) over 10 repeated cycles. This study suggests that the appropriate control of bifunctional catalysts can lead to powerful potential for high H 2 production performance in SESRM. [ABSTRACT FROM AUTHOR]

• Mesoporous Ni/La 2 O 3 catalyst with large specific surface area was synthesized. • Superior coke resistance was demonstrated for dry reforming of methane. • The activation of CO 2 was promoted by the interface between Ni and La 2 O 3. • The increased interface was beneficial to suppress carbon deposition. This paper describes the synthesis of ordered mesoporous Ni/La 2 O 3 catalysts (denoted as Ni/La 2 O 3 -m) for dry reforming of methane and investigates the synergistic effect of Ni/La 2 O 3 interfaces on the activation of CO 2. The resultant nanostructured La 2 O 3 possessed high specific surface area of 211.5 m2/g, and Ni/La 2 O 3 -m catalysts maintained the initial morphology upon thermal treatment. The mesostructure was beneficial to obtain and maintain Ni nanoparticles with sizes between 4–6 nm. Ni/La 2 O 3 -m catalysts exhibited superior activity and stability in dry reforming of methane, showing excellent performance in activating both CH 4 and CO 2 due to more catalytically active Ni sites and increased interfaces. In situ DRIFTS indicated that bidentate carbonate participates in coke elimination. Combined with CO 2 -TPD and density functional theory (DFT) calculations, we found that Ni/La 2 O 3 -m catalyst has stronger capability to promote the formation of bidentate carbonate due to the increased interfaces by enhancing Ni dispersion, which leads to better stability by suppressing the coke deposition. [ABSTRACT FROM AUTHOR]

Review: 225 refs. [ABSTRACT FROM AUTHOR]