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Abstract: A series of Ni2+–Fe2+–Al3+ hydrotalcite (HT) catalysts with varying compositions have been prepared by coprecipitation from Fe2+. The structure and properties of the catalysts were carefully characterized by various methods such as XRD, EXAFS, TGA, TPR, N2 adsorption/desorption, XPS and H2 chemisorption. It was shown that pure HT structures can only be prepared at low Fe2+ concentrations, while mixed oxide phases with spinel structure will form simultaneously at high Fe2+ concentrations. Pure HT structures are very important for small particle size, narrow size distribution and large surface area of the resulting catalysts. XPS study demonstrated Fe enrichment on the catalyst surfaces, which might have partly contributed to the low hydrogen chemisorption capacity for the Fe-containing catalysts. [Copyright &y& Elsevier]

Abstract: Pre-reforming of natural gas has been studied on a nickel catalyst at 480–550°C and 20bar using a TEOM (Tapered Element Oscillating Microbalance) reactor. The focus has been on carbon formation and the main objective was to study the influence of C2–C3 hydrocarbons in the methane feed on carbon deposition on the catalyst. Coking thresholds for different mixtures of hydrocarbons were determined by varying the steam to carbon (S/C) ratio at various temperatures. The steady-state coking rate decreases with increasing S/C ratio, and increases with increasing carbon number of the hydrocarbon. Unsaturated hydrocarbons show a strong effect on coking rates and on carbon thresholds. For mixtures of methane and propane/propene, the steady-state coking rate as well as the coking threshold decreased with a decrease in the mole fraction of propane/propene and with an increase in the hydrogen mole fraction. The coking rate revealed a complicated temperature dependency, and a minimum in the coking rate and in the coking threshold was detected at 500°C. A relationship between the critical steam to carbon ratio and the thermodynamic carbon activity is also developed based on a suggested reaction mechanism, which can properly predict the role of hydrocarbon, hydrogen and water in carbon formation. [Copyright &y& Elsevier]

Abstract: Cu/CNF and Cu/CeO2/CNF catalysts have been synthesized and characterized on different nanostructured carbon nanofibers (CNF). The samples have been tested in isopropanol dehydrogenation. Cu/CNF show similar activity to Cu catalysts supported on activated carbon. Cu/CeO2 nanotubes have been synthesized on the CNF surfaces. The Cu/CeO2 nanotubes exhibit much higher activity and lower activation energy than Cu/CNF. The selectivity towards acetone depends on the fraction of CeO2 in the composites. High activity and selectivity has been achieved with a Cu12Ce5/CNF catalyst. [Copyright &y& Elsevier]

Abstract: A series of silica supported Fe catalysts were prepared by different methods in order to obtain varying Fe particle sizes. The catalysts were characterized by XRD, TPR, BET, and TEM. The CNT growth from CO disproportionation was studied in order to establish a relationship between the CNT growth rate and the particle size. We found that there is an optimum catalyst particle size at around 13–15nm which will lead to the maximum growth rate. The influence of the metal loading on the growth rate was also investigated. A CNT growth model has been formulated to explain the experimental results. [Copyright &y& Elsevier]

Catalytic converting the lignin-derived bio-oil to liquid fuel is one promising methodology to reduce the dependence on petroleum-based fuel while easing the atmospheric carbon dioxide burden. Hydrodeoxygenation (HDO) is one commonly used method to convert and upgrade bio-oil from biomass. In the present work, a Ru-promoted MoFeP/Al 2 O 3 catalyst was prepared and evaluated the HDO performance by converting two model compounds, guaiacol and anisole with a batch reactor at 250 °C. This catalyst shows a quite good HDO performance over the two model compounds, in which, oxygen was removed from the phenolic and hydrocarbons were produced as the product. Kinetic studies were also performed to build the reaction network and elucidate the reaction pathway of guaiacol and anisole HDO reactions. The primary, secondary, and tertiary products can be identified for the HDO reactions. A better understanding of HDO chemistry from the fundamental study can lead to more efficient catalysts for the target products. [Display omitted] • A highly active Ru-MoFeP/Al 2 O 3 was proposed in HDO reaction. • Reaction network of guaiacol and anisole HDO reaction were proposed. • Primary product, secondary or tertiary products can be identified. [ABSTRACT FROM AUTHOR]

• Microkinetic analysis is used to screen perovskites for methane partial oxidation. • The catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3. • Bulk oxygen vacancy formation energy is identified as a single descriptor. • 667 combinations of A- and B-cations have been screened in terms of stability. • SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are identified as catalyst candidates. DFT calculations and descriptor-based microkinetic analysis have been performed to screen ABO 3 perovskite catalysts for methane partial oxidation. The scaling relations indicate the adsorption energies of H@O and CH 3 @B have the capability of representing the energetics of methane oxidation, and bulk oxygen vacancy formation energy is identified to be a better single descriptor of the kinetics. The resultant volcano-shaped plot shows the catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3 , which agrees with the experimental findings and thus validates our theoretical predications. By screening 667 combinations of A- and B-cations based on electron neutrality, structural tolerance factors, and experimental verification, 77 ABO 3 have been identified to be stable. Of them, SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are located at the summit of the volcano, which also exhibit satisfactory CO selectivity and enhanced carbon resistance compared to LaFeO 3 , and may act as the oxygen carrier candidates. [ABSTRACT FROM AUTHOR]

Catalytic conversion of cellulose to diols is an attractive approach in the valorization of biomass, because of the high atom efficiency of the reaction process. The work here highlights the potential of cellulose as a renewable feedstock to produce value-added chemicals, especially vicinal diols. The catalytic conversion of cellulose in water on Ni-Cu/4ZnO-CNT catalyst is discussed, with a focus on four main reaction pathways leading to the formation of C 2 , C 3 , C 4, and C 6 vicinal diols, involving hydrolysis, retro-aldol condensation, hydrogenation, isomerization, dehydrogenation, and thermal side reactions. By modifying the Ni-Cu bimetallic active sites, the pathways can be manipulated, resulting in selective retro-aldol condensation C-C cleavage, leading to a shift towards the selective production of either ethylene glycol (EG) or 1,2-propylene glycol (1,2-PG). Finally, we explore the optimization of reaction conditions to tune product selectivity. This study provides important insight into the catalytic conversion of cellulose and offers promising avenues to produce value-added chemicals from renewable feedstocks. [Display omitted] • Bimetallic NiCu/ZnO-CNT catalyst was proposed in direct cellulose conversion to diols. • Reaction pathway was built based on the kinetic studies. • Product selectivity can be tuned via varying the Ni-to-Cu ratio. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activity and stability in the water–gas shift reaction have been tested for Au-based catalysts prepared by deposition of Au from colloid solutions. The supports that have been used are TiO2, TiO2 supported on carbon nanofibres (CNF) and CNF. Thermal treatments of the samples show that the Au particle size depends on the support material and hence the interaction between the Au particles and the support. In situ X-ray absorption spectroscopic (XAS) measurements during the water–gas shift reaction show no changes in the first Au–Au coordination number for the catalysts containing CNF. Furthermore, improved short-time stability is obtained compared to the AuTiO2 catalysts. The improved stability is achieved by the CNF stabilising small TiO2 particles and hence prevent subsequent sintering of the Au particles. [Copyright &y& Elsevier]

Enhanced electrochemical reduction of CO 2 to syngas on CuZnOCNT catalyst. • Copper doping on ZnO shifts the ECR activity towards CO formation closer to the top of the volcano. • The optimal amount of copper is around 20 at% for CO formation from electrochemical reduction of CO 2. • Higher amount of Cu doping leads to metallic Cu segregation, resulting in higher H 2 evolution activity. • The 14Cu86ZnO/CNT catalyst shows best performance in terms of syngas (1:1 ratio) production at -0.9 V, better than Ag foil. Electrochemical CO 2 reduction is a promising method for the production of CO 2 neutral fuels and chemicals from renewable electricity. ZnO supported on CNT is a low-cost electro catalyst that can produce syngas from CO 2 and H 2 O. A rational catalyst design strategy for further improvement of the ZnO/CNT catalyst is to dope with copper to strengthen the binding energy of the CO intermediate, which could improve the activity. In this work, a series of CuZnO/CNT catalysts with intimate Cu and Zn contact and various Cu loadings are prepared. By varying the copper content we show that the synergy of copper and zinc improves the activity for CO formation, and the optimal copper content is 20 at%. On hydrogen evolution, the addition of copper has a two-fold effect. This reaction is enhanced by the reduced ZnO particle size obtained when copper is added, but at similar particle sizes of ZnO, a suppression is observed with increasing copper content as CO evolution is enhanced. Stability tests showed that pure ZnO phase is more stable than metallic copper on ZnO. Compared with polycrystalline silver, the CuZnO/CNT catalysts are more active for syngas formation at a useful CO: H 2 composition. This work demonstrates that the viability of DFT based rational design of electrochemical CO 2 reduction catalyst. By varying CuZnO composition as well as crystallite size, one is able to tune the electrochemical reduction activity towards CO and H 2 , and therefore achieve desired syngas ratio. [ABSTRACT FROM AUTHOR]

• Small Ni particles exhibit higher steam methane reforming activity than large ones. • The size-dependent activity of Ni catalysts is related to the surface-dependent activity. • Ni(2 1 1) is the most active surface for steam methane reforming. • Decreased Ni(2 1 1) surface fraction results in reduced Ni activity as size increases. Fundamental understanding of the size-dependent activity is essential to harness powers of the nanocatalysts. Here we report an experimental and theoretical study of the Ni particle size effect on activity of steam methane reforming (SMR) to achieve a better understanding of the size dependence of kinetic behavior at an atomic level. A kinetic study illustrated the higher forward methane turnover frequency on the smaller sized Ni particles. The size-dependent activity was well reproduced by microkinetic modeling on a truncated octahedron model with the kinetic parameters estimated by the improved unity bond index-quadratic exponential potential (UBI-QEP) and the Brønsted–Evans–Polanyi (BEP) relationship. Microkinetic modeling suggested that the size-dependent activity of Ni catalysts is associated with the surface-dependent activity. Much higher activity of Ni(2 1 1) than Ni(1 1 1) and Ni(1 0 0) accompanied by decreased Ni(2 1 1) surface fraction results in reduced Ni activity as particle size increases. The activity of Ni(1 1 1) is limited by high free energy barriers, while that of Ni(1 0 0) is limited by site blockage by C* and CH*. This work offers a feasible approach to gain insight into size-dependent activity and to aid rational catalyst design for SMR in which preparing extremely small Ni particles (≤6 nm) might be a good strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method to control the surface Mo:C ratio by carbonization flow is discovered for the first time. • The relationship between the surface Mo:C ratio and the reactivity is established. • The low temperature water gas shift reaction activity depends on the electron transfer capability of the surface. • The catalysts with low Mo:C ratio improve catalyst stability. The low-temperature water–gas shift (WGS) reaction is an important industrial process for producing hydrogen and reducing carbon dioxide emissions. The α-MoC 1-x catalysts have shown promising performance in WGS reactions, but their activities are highly dependent on the surface structure. In this study, we investigated the effect of surface Mo and C ordinations on the low-temperature WGS activity of Pt/α-MoC 1-x catalysts using both experimental and theoretical methods. Our results reflected that as Mo: C ratio decreases, the surface free carbon and reduced number of Mo active sites led to a weakened electron transfer ability, resulting in poor catalytic activity. The 0.4% Pt/α-MoC 1-x -50 catalyst displayed superior hydrogen production activity and low apparent activation energy (E app = 58.5 kJ/mol) at low temperatures (100–200 °C). Our density functional theory (DFT) calculations revealed that the high reactivity of the 0.4% Pt/α-MoC 1-x -50 catalyst was due to the strong electron transfer capability and increased number of surface Mo active sites. This study provides new insights into the structure–activity relationship and stability of α-MoC 1-x catalysts for the WGS reaction and lays the foundation for the design of WGS catalysts with high activity and stability at low temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • A transient kinetic model for half-reactions in the redox cycle. • A systematic study for 14 metal chlorides on the CuCl 2 /γ-Al 2 O 3 -based catalysts. • Tuning the redox behavior by affecting the reduction and oxidation steps. • Three types of promoters with different rate-determining steps. • Valuable insights into the reaction process and mechanism. This study investigates the promoter effects of 14 metal chlorides (NaCl, KCl, RbCl, CsCl, MgCl 2 , CaCl 2 , SrCl 2 , CeCl 3 , PrCl 3 , NdCl 3 , ErCl 3 , FeCl 3 , YCl 3 , and SnCl 3) on the CuCl 2 /γ-Al 2 O 3 -based catalysts used for ethylene oxychlorination. The study combines transient experiments of the two half-reactions in the redox cycle to understand the effects of different promoters on the reduction and oxidation rates of the catalysts. The results show that promoter doping can tune the redox behavior of the CuCl 2 /γ-Al 2 O 3 -based catalysts, affecting the reduction and oxidation steps, and the rate-determining step (RDS) changed between reduction and oxidation steps through the effects of different promoters. All the promoters have a positive effect on the reaction rate at steady-state, but the impact of promoter identity on steady-state CuCl 2 concentration is variable and related to the electronegativity of the promoter metal. This work provides a better understanding of the reaction process and mechanism and highlights the potential of promoter doping for improving the efficiency and stability of CuCl 2 / γ -Al 2 O 3 -based catalysts in ethylene oxychlorination. The approach of both transient and steady-state kinetic modeling and simulation is a reliable and efficient method to study promoter effects on reduction–oxidation reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both size and support effects of Au catalysts are explored for MAL conversion. • The Au edge site is identified as the main active site for MMA generation. • A kinetics strategy for disentangling Au geometric and electronic effects is presented. The direct oxidative esterification of methacrolein (MAL) has drawn considerable attention as a promising route to produce methyl methacrylate (MMA). Here, we report a kinetics strategy to identify the active sites of Au catalyst for its disentanglement of geometric and electronic effects on this reaction. A series of Al 2 O 3 and CeO 2 supported Au catalysts are prepared by urea deposition–precipitation method, whose particle sizes are tailored by changing the vacuum-drying temperature. Their catalytic activity is correlated with Au particle size based on a crystal structure modelling, in which the Au edge site is identified as the main active site. The reduction in the valence electron population of Au 5 d states facilitates the adsorption of MAL, thus the positive core-level shift of Au 4f levels for each support gives rise to a higher production of MMA. This kinetics strategy could be extended to the design of other metal catalysts for this reaction. [ABSTRACT FROM AUTHOR]

The activated carbon treated at different temperatures was performed as a catalyst for the oxidation of glycerol to glycolic acid. Heat treatment at suitable temperature could promote the enrichment of ester and carboxyl functional groups with strong electronegativity, which serves as the efficient active site for the glycerol oxidation. Therefore, the optimal AC-400 catalyst with more ester and carboxyl groups shows excellent catalytic activity (0.0039 mol/g Cat /h) and GLYOA selectivity (53.2%). [Display omitted] • The efficient oxidation of glycerol to glycolic acid was realized over heat treated activated carbon. • Heat treatment tuned the composition and electronic structure of oxygen-containing functional groups. • The ester and carboxyl functional groups with strong electronegativity enhanced the adsorption and activation of glycerol. Exploring efficient and cheap catalyst for the selective oxidation of glycerol to valuable carboxylic acids is a critical and complicated challenge. Herein, we innovatively realized the efficient oxidation of glycerol to glycolic acid over metal-free catalyst under mild conditions via carbon material defect engineering. Multiple characterizations revealed that the stepwise functionalization of active carbon caused by simple high temperature control is adopted to fine-tune the composition and electronic structure of oxygen-containing functional groups. Specifically, the abundant ester and carboxyl functional groups exhibit stronger electronegativity than the hydroxyl group, and this enhanced electronic coupling effect strengthens the adsorption of glycerol, thus improving the catalytic activity. Kinetic analysis and density functional theory calculations demonstrated that the oxygen-containing functional groups (mainly ester and carboxyl) could promote the C–H bond activation of RCH 2 O* intermediate and once C–C bond cleavage of glyceric acid, ensuring the high selectivity of glycolic acid (53.2% over AC-400 catalyst). We anticipate that this work could sheds some light on the application and design of more new type of carbon-based metal-free catalysts in the aqueous phase oxidation of various polyols. [ABSTRACT FROM AUTHOR]

[Display omitted] • Substitution of transition metals for Cr increases the acidity of the adjacent O. • Linear scaling relations are established to identify the PDH activity descriptor. • High propylene selectivity of the M 1 -Cr 2 O 3 catalysts is achieved. • Cu 1 -Cr 2 O 3 is predicted to be the best catalyst for PDH among the 13 doped Cr 2 O 3. The catalytic behavior of M 1 -Cr 2 O 3 (M = Mn-Cu, Ru-Ag, and Os-Au) in propane dehydrogenation (PDH) has been studied by employing microkinetic modeling combined with results from periodic DFT + U calculations. Calculated results indicate that most of the single atoms concerned can be stably present on the Cr 2 O 3 surface. The adsorption energy calculations and Bader charge analysis demonstrate that the acidity of the O sites adjacent to the M sites would be enhanced upon doping, which in turn strengthens the atomic H adsorption and the co-adsorption of various PDH species. The surface H formation energy is identified as the reactivity descriptor for PDH over the M 1 -Cr 2 O 3 catalysts, and a volcano curve of the PDH activity is obtained. By calculating the difference between the propylene dehydrogenation and desorption barriers, it is found that some M 1 -Cr 2 O 3 catalysts show improved selectivity towards propylene, as compared to Cr 2 O 3. Comparison between the formation barriers of H 2 and H 2 O reveals that single-atom doping has no apparent negative effect on the catalytic stability of the Cr 2 O 3 surface. The Cu 1 -Cr 2 O 3 catalyst is finally identified as the most promising catalyst for PDH among the 13 M 1 -Cr 2 O 3 catalyst candidates, considering the catalytic activity, selectivity, stability, and cost. [ABSTRACT FROM AUTHOR]

Abstract: Au catalysts have been prepared (i) on TiO2, (ii) on carbon nanofibres (CNF) and (iii) on TiO2 deposited onto CNF. Catalysts prepared from deposition-precipitation (DP) and from colloid solutions have been characterised using XRD, TEM, TGA and XAS and tested in the water–gas shift (WGS) reaction. DP yields large Au particles (>50nm) on CNF-containing supports. High Au dispersion on carbon nanofibres requires preparation via other methods such as colloid formation. Au particle growth is more pronounced during the synthesis steps than during thermal treatments. This increase is not observed for the Au particles on TiO2 but only when CNF is present, indicating that the surface properties of TiO2 are altered by the CNF. TiO2 XANES analyses show that distortions in the lattice symmetry of TiO2 are introduced when the oxide is deposited on CNF. The distortion of the TiO2 structure by the CNF may also introduce changes that promote the turnover frequencies. The WGS activity significantly improves when titania is present. This shows that coexistence of Au and TiO2 is needed to obtain high catalytic activity in the WGS reaction, indicating that the active sites are either on the Au–TiO2 interface or that the reaction follows a bifunctional mechanism. [Copyright &y& Elsevier]

Abstract: The rational design of the carbon nanofiber catalysts for oxidative dehydrogenation of ethylbenzene (ODE) has been discussed based on a reviewed reaction mechanism. The synthesized carbon nanofibers with systematically varied graphitic platelet orientations have been used as a model system for the rational catalyst design, in respect to the carbon nanofiber properties such as the amount of basic groups, the crystallinity, and the ratio between the prismatic area and the basal plane area. Well defined carbon nanofibers have been synthesized by hydrocarbon or carbon monoxide decomposition on the sub-iron group catalysts and at selected preparation conditions. The catalytic test in a fixed bed reactor at a temperature of 400°C shows that the stable activity and selectivity can be obtained on the well-defined carbon nanofibers catalysts. Removing the residual metal in carbon nanofibers does not evidently influence the catalytic behavior whereas the lower conversion of ethylbenzene can be observed on the high-temperature treated carbon nanofiber samples. No clear evidences are found for the catalytic behavior being related to the surface area and graphitization degree of carbon nanofibers. The basic oxygen-containing groups are identified as the active sites by TPD–MS and a special method suggested by Boehm. The ratio between the prismatic surface area and the basal area has been identified as the most important parameter for the rational catalyst design. The fish-bone catalysts CNF 20 seems to be the best catalyst in the samples studied in the present work, due to the large number of basic edge groups, the optimum ratio between the prismatic and basal plane area. It can result in a delicate balance in the redox catalytic cycle. As a consequence, the formation of CO2 can be reduced. [Copyright &y& Elsevier]

Abstract: Nanocomposite catalysts containing carbon nanofiber (CNF) and Cu-Ce-Zr mixed metal oxide (MMO) have been prepared by homogeneous co-precipitation with urea. The water-gas shift (WGS) reaction has been used as test reaction. The CNF-containing nanocomposite catalysts exhibit similar overall catalytic activity and stability as the corresponding CNF-free catalyst. Thirteen weight percent of the MMO could be replaced by CNF without decreasing the overall activity and stability of the catalyst. The specific activity of the nanocomposites based on the total metal oxide content is similar or higher than the activity of the CNF-free material, depending on the CNF content. Similar activation energies are, however, obtained for the CNF-free and CNF-containing materials. We cannot exclude that the CNF material acts as reaction promoter under certain conditions, but suggest that the impact of CNF addition on the precipitation of the mixed oxide particles, and hence the catalytic activity relative to the CNF-free MMO, should also be considered. CNF may be regarded as inert dispersing agent material improving the precipitation of the MMO under conditions where the co-precipitation of the MMO precursors does not result in materials with high surface area. [Copyright &y& Elsevier]

Abstract: In order to investigate the effect of cerium oxide on Cu–Zn-based mixed-oxide catalysts four catalyst samples were characterized by means of XRD, in situ XANES and thermogravimetric analysis. The activity of the catalyst samples was tested for the forward water–gas shift reaction. Cerium oxide was found to increase the crystallinity of the ZnO phase indicating a segregation of the Cu and ZnO phases. The TOF of the water–gas shift reaction based on chemisorption data was found to be independent of composition and preparation conditions of the four catalyst samples. In contrast, the catalyst stability depends on composition and preparation conditions. Cerium oxide impregnated before calcination of the hydrotalcite-based Cu–Zn precursors leads to a more stable water–gas shift catalyst. [Copyright &y& Elsevier]

• Cofed C 2 H 4 hydrogenated faster than CO, and mainly produced ethane and higher olefins. • Cofed C 2 H 4 followed a similar reaction mechanism as Fischer-Tropsch synthesis. • Cofed C 2 H 4 enhanced chain growth probability and increased C 3+ O/P ratio. • Hydrocracking of cofed C 2 H 4 formed C 1 monomer and the C 1 monomer got further incorporated into the growing chain. Understanding the secondary reactions of olefins in Fischer Tropsch Synthesis (FTS) is crucial for enhancing olefin selectivity in Fischer Tropsch to Olefin (FTO) reaction. Equimolar ethene towards CO was used as a probe to be cofed into the syngas (H 2 : CO = 2) to study the effect on the product distribution over cobalt-based catalysts supported on γ-alumina, α-alumina and carbon nanotube (CNT), respectively. The experiments were performed at T = 210 °C; P tot = 1.85 bar, P CO = 0.11 bar; P H2 = 0.22 bar; P C2H4 = 0 or 0.11 bar with Ar as the balance. On all three catalysts, ethene co-feeding at this concentration inhibited CO conversion and the products were mainly from ethene. The products showed similar Anderson-Schulz-Flory (ASF) distribution as typical for FTS products. Ethene co-feeding can both enhance the chain growth probability and significantly increase the O/P ratio of C 3 -C 6 hydrocarbons. An isotopic switch from 12CO/H 2 /Ar→13CO/H 2 /C 2 H 4 /Kr proved that ethene can hydrocrack to C 1 intermediates and be incorporated into the growing chain. On the other hand, the hydrogenation activity can be significantly suppressed due to the H 2 scavenging effect and possibly competitive adsorption with H 2. [ABSTRACT FROM AUTHOR]

• High selectivity of core-shell alloy catalysts for propane dehydrogenation. • Linear scaling relations are established to identify the descriptor. • Microkinetic modeling is carried out to obtain turnover frequency. • Co@Pt is the best catalyst by making a compromise between activity and selectivity. Microkinetic analysis combined with the results obtained from density functional theory calculations has been performed to examine the catalytic activity and selectivity of Pt-based core-shell alloy catalysts for propane dehydrogenation. Calculated results indicate that substitution of 11 late transition metals for the core region of Pt nanoparticles would significantly modify the electronic structure of the surface Pt atoms through the strain effect and charge transfer. The core-shell catalysts are found to have less negative propylene adsorption energies and higher activation energies for the dehydrogenation reactions than Pt, thus giving rise to a lower catalytic activity and a higher selectivity toward propylene. Linear chemisorption energy and transition state energy scaling relations hold very well in the present work, and the adsorption energy of propylene is identified to be a good descriptor to represent the overall kinetics. The scaling relations also suggest that a higher catalyst selectivity toward propylene can only be achieved at the expense of a lower catalytic activity for propane dehydrogenation. If a compromise is made between catalytic activity and catalyst selectivity, Co@Pt is proposed to be the best core-shell catalyst for propane dehydrogenation. [ABSTRACT FROM AUTHOR]

• Hydrophobic TS-1 with wormhole-like mesopores is synthesized. • Au/HTS-1 catalyst shows high stability towards direct propene epoxidation. • Mesopores with enhanced mass transfer ability is essential for stability. • Au/HTS-1 catalyst shows high PO formation rate of 150 g po h−1kg Cat −1 over 100 h. Designing highly efficient Au/Ti-containing catalysts for propene epoxidation with H 2 and O 2 harbors tremendous scientific and industrial importance. In this work, novel hydrophobic hierarchical TS-1 (HTS-1) with wormhole-like mesopores (ca. 45 nm) and small crystal size (100 nm) is firstly synthesized by a two-step crystallization method using CTAB as template. Gratifyingly, the Au/HTS-1 catalyst shows simultaneously high PO formation rate of 150 g po h−1kg Cat −1 without any promoter additive, PO selectivity of 90% and impressive stability of 100 h, which are much better than traditional Au/TS-1 catalyst. Furthermore, the intrinsic reason for the enhanced performance is elucidated by multi-techniques such as N 2 physisorption, HRTEM, TGA, FT-IR and 29Si NMR. Interestingly, it is found that the coke in 0.10 wt% Au/HTS-1 catalyst partly reside in mesopores, alleviating the deactivation of micropore blocking. Moreover, the enhanced mass transfer ability and higher hydrophobicity of Au/HTS-1 catalyst also lead to reduced coke weight and absence of aromatic coke. [ABSTRACT FROM AUTHOR]

• For selectivity and stability test, CeO 2 -Ni shows the best performance. • Forward turnover rate is independent of CO 2 partial pressure. • TOF obtained from G plot is in perfect agreement with experiment value. • The increased basicity and decreased electronegativity help to activate the CO 2. Here we provide new mechanistic and kinetic insights into the functions of oxides on Ni catalysts in methane dry reforming combining kinetic studies with density functional theory (DFT) calculations. Hydrotalcite derived Ni catalysts with a small amount of oxide additive (CeO 2 , ZrO 2 , ZnO) as promoters are synthesized and characterized by different techniques, X-ray diffraction (XRD), X-ray fluorescence (XRF), N 2 physisorption, H 2 chemisorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis combined with mass spectrometry (TGA-MS). Regarding H 2 /CO ratio, the CeO 2 -Ni shows the highest the values along all the temperatures. Moreover, the CeO 2 -Ni catalyst has the best stability among the four catalysts, while ZnO-Ni experiences the most severe deactivation. Kinetic studies in terms of reaction orders and activation energies are performed and compared to the DFT investigations, to assess the functions of oxide promoters. The CeO 2 -Ni catalyst shows the lowest apparent activation energy for CO 2 activation, and it is also found that forward turnover rate is independent of CO 2 partial pressure for all the samples. In DFT calculations, CO 2 is more favorable to be activated on the support and the TOF obtained from G plot is in perfect agreement with our experiment value. In addition, it is also found that basicity of oxide additives and electronegativity of metal element can be well correlated to the activation of CO 2 and catalyst's deactivation. In general, both the increased basicity of oxide and the decreased electronegativity of metal element help to promote the CO 2 activation and enhance the catalyst's stability. We propose that the CeO 2 -Ni catalyst has best performance for CO 2 activation, thus leading to a higher surface oxygen concentration to oxidize the carbon on the catalysts, which prolongs the catalyst's life. [ABSTRACT FROM AUTHOR]