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To solve serious energy and environmental crises caused by rapid industrial development, the formation of heterostructured photocatalysts is a promising approach for efficient and scalable H2 produ...

The synthesis of phosphine‐based functional covalent organic frameworks (COFs) has attracted great attention recently. Herein, we present two examples of triphenylphosphine‐based COFs (termed P‐COFs) with well‐defined crystalline structures, high specific surface areas, and good thermal stability. Furthermore, rhodium catalysts with these P‐COFs as support material show high turnover frequency for the hydroformylation of olefins, as well as excellent recycling performance. This work not only extends the phosphine‐based COF family, but also demonstrates their application in immobilizing homogeneous metal‐based (e.g., Rh‐phosphine) catalysts for application in heterogeneous catalysis., A turn up for turnover: Two triphenylphosphine‐based COFs (P‐COFs) that stack in an eclipsed AA manner and have high crystallinity, high specific surface areas and good thermal stability have been synthesized. The application of these P‐COFs in phosphorus coordination catalysis was demonstrated by the hydroformylation of olefins over supported Rh/P‐COFs catalysts, which showed high turnover frequencies and excellent recycling.

PtSnNa/γ-Al2O3 catalyst is widely used in the dehydrogenation of light alkane. This paper reports a new fabrication method of the catalyst. In the work, γ-Al2O3, SnCl4 and NaCl were ball milled to upload Sn and Na+ onto the support instead of the conventionally used immersion method. The subsequent baking procedures frimly fixed Sn onto the support, which could disperse Pt introduced by immersion. The effects of Sn and Na+ additives on the catalytic performance of PtSnNa/γ-Al2O3 catalyst were investigated. It was found that the appropriate molar ratio of Sn/Pt was 6:1 while the favorable weight percentage of Na+ was 0.90%. Compared with the reaction catalyzed by the industrially employed PtSnNa/γ-Al2O3 catalyst, the conversion of propane and the selectivity of propylene had been greatly improved, which were 26.97% and 99.18% respectively after 12 h reaction.

A novel dual bed reactor packed with a combination of a zeolite (H-modernite or H-ferrierite) catalyst and a CuZnAl catalyst was proposed to realize direct ethanol (EtOH) synthesis from dimethyl ether (DME) and syngas (CO + H2). DME and CO were firstly introduced into the upper zeolite bed to commence the carbonylation reaction, and then H2 was directly introduced into the CuZnAl catalyst bed below to accomplish the hydrogenation of methyl acetate (MA) produced at the first catalyst bed. In this novel dual bed process, DME and CO were introduced into the reactor at the top of the first catalyst bed layer, but H2 was introduced into the second catalyst bed layer directly through an inner stainless steel tube equipped with evenly distributed holes. Benefitting from the precise control of the distribution of the reactants on the surface of different catalysts, an enhanced catalytic performance was obtained compared with the conventional dual bed reactor which introduced DME and syngas into the reactor simultaneously. The synergistic effects offered by this novel dual bed reactor were further confirmed by numerous comparative tests. Our results show that the excellent catalytic performance in this novel dual bed reactor was ascribed to the improved CO partial pressure in the upper zeolite catalyst bed. Compared with the conventional dual bed reactor, both DME conversion and EtOH yield were almost doubled in this novel dual bed reactor packed with the combination of the H-ferrierite and CuZnAl catalysts.

The covalent triazine frameworks (CTFs) have recently become a new generation of organic semiconductor for photocatalytic hydrogen production from water splitting because of their great application potentials. However, the CTFs need to be combined with noble-metal-cocatalysts to achieve photocatalytic water splitting. Herein, we reported the noble-metal-free Ni2P/CTF composites as an efficient catalyst for photocatalytic hydrogen evolution. With increasing the Ni2P alloy loading on the surface of CTF, the photocatalytic activity increases obviously and then decreases gradually, and the highest photocatalytic H2 evolution rate is achieved for 2.8%Ni2P/CTF, which is almost the same as that of 3.0%Pt/CTF photocatalyst. It has been revealed that the Ni2P alloy act as a cocatalyst for effectively suppressing the recombination of photogenerated electrons and holes, promoting the separation and migration of the charge carriers, thereby improving the efficiency of photocatalytic H2 evolution. This work provides a promising strategy for preparation of cheap and stable photocatalytic system based on CTF for efficient photocatalytic hydrogen evolution under visible-light irradiation.

The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD, nitrogen adsorption, NH 3 -TPD, TG, H 2 -TPR and TPO techniques combined with propane dehydrogenation tests. It has been shown that SUZ-4-supported PtSnNa (PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5, owing to its higher catalytic activity and stability. Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts. The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity. In contrast to ZSM-5-supported catalysts, Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition. This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H 2 PtCl 6 into the zeolite. In contrast, the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels, followed by transformation to highly dispersed Pt clusters during calcination. In the case of the PtSnNa/ZSM-5, the interactions between Sn oxides and the support were lessened, owing to the weaker acidity of the ZSM-5 zeolite. The dispersed Sn oxides were therefore easier to reduce to the metallic state, thus decreasing the catalytic activity for hydrocarbon dehydrogenation.

A novel honeycomb-shaped PtSnNa/γ-Al2O3/cordierite monolithic catalyst (Pt 0.5%, Sn 0.9%, Na 1.0%, relative to Al2O3 weight) was developed and its catalytic performances in propane dehydrogenation were tested and compared with the classical granule catalyst with same Pt, Sn and Na contents under the conditions of 0.1 MPa, 590 °C, C3H8/H2 at 3/1 (molar ratio) and gas hourly space velocity (GHSV) at 155 h−1. Interestingly, despite the generated coke amount and exposed Pt fraction, the honey comb-shaped structure of monolithic catalyst exerted important influences on its catalytic activities and led to the advanced catalytic performances over the granule catalyst.

A carbonylcobalt catalyst, immobilized by poly(4-vinylpyridine) (P4VP) through N→Co coordination bonds, has been prepared by solvothermal method. It has been revealed that the pyridine fragments in the polymer catalyst act not only as promoters to improve the catalytic performance of the carbonylcobalt catalyst for alkoxycarbonylation of ethylene oxide to methyl 3-hydroxypropanoate but also as stabilizers to enhance the reusability of the polymer catalyst. Furthermore, the polymer catalyst could be easily separated by filtration and reused with only a slight loss of catalytic efficiency.

SUZ-4-based Pt-Sn catalysts with different sodium ion contents were prepared through sequential impregnation method. The structural and catalytic properties of the catalysts were studied by using various techniques combined with micro-reactor tests. The experimental results showed that PtSnNa/SUZ-4 catalysts exhibited high durability, high propylene selectivity and high stability with adequate sodium ion content. Sodium ion additives neutralized the strong acid sites and prevented the formation of coke. However, excess sodium ion not only reduced tin species to metallic tin, which reduced the catalyst activity by forming PtSn alloys, but also led to more Pt particles inside the pore of zeolite, which were easily deactivated by coke. It was found that catalysts with the sodium ion content at 0.5–1.5wt % led to the highest propane conversion and propylene selectivity.

MnOx/TiO2 (anatase) nanosheets (NS) with a preferentially exposed {001} facet was found to be a better catalyst for selective catalytic reduction (SCR) of NO than conventionally employed MnOx/TiO2 nanoparticles (NP) with the {101} facet preferentially exposed, affording both high NO conversion and high N2 selectivity at 80–280 °C. Further investigations indicated that Mn3+ as the major species on TiO2 (NS) was incorporated into octahedral vacancies with a lower polymerization degree, resulting in high catalytic activity for SCR and low activity for NH3 oxidation, thus restraining the undesirable N2O generation. In comparison, on the surface of TiO2 (NP), Mn4+ as the major species was incorporated into tetrahedral vacancies in a highly polymerized state, leading to lower NO conversion and lower N2 selectivity. The results indicate that it is possible to enhance the low-temperature SCR activity of the catalysts by tailoring the preferentially exposed facet of TiO2.

The catalytic properties of Cu–ZnO catalysts for glycerol hydrogenolysis to 1,2-propanediol (1,2-PDO) were tested in a fixed-bed reactor at 250 °C and 2.0 MPa H2. The relation between composition, surface properties, and catalytic performance of glycerol hydrogenation of Cu–ZnO catalysts was studied using nitrogen adsorption (BET methods), XRD, H2 temperature-programmed reduction, and N2O chemisorptions. It was found that there was a close link between the surface CuO amount of Cu–ZnO catalyst and the reactivity for glycerol hydrogenation. The Cu–ZnO catalyst (Cu/Zn = 1.86) which had the highest surface Cu amount showed the best catalytic activity for glycerol hydrogenolysis. Furthermore, Cu–ZnO catalyst presented good stability and remarkable catalytic activity for glycerol hydrogenolysis to 1,2-PDO using raw glycerol derived from the fat saponification as feedstock.

Theoretical calculations have provided fundamental insights into the possible pathways for the H/D exchange of isobutane with H-ZSM-5 zeolite at room temperature. It is theoretically demonstrated that neither the direct exchange mechanism nor the indirect bimolecular hydride transfer mechanism is an efficient route for isobutane activation due to high activation barriers, which possibly prohibit H/D exchange at low temperatures. It is revealed that a trace of olefin impurities can considerably accelerate the formation of an alkoxyl intermediate which is involved in the bimolecular hydride transfer mechanism. Once the alkoxyl intermediate is generated from the olefin impurities, the catalytic cycle is self-sustaining. On the other hand, the theoretical calculations also illustrate that the extra-framework aluminum (EFAl) species in the dealuminated zeolite has no obvious promotional effect on the H/D exchange. Furthermore, our calculations are also consistent with the experimental results.

The surface interaction of an iron-improved MnOx/TiO2 (anatase) catalyst for the selective catalytic reduction of nitric oxide was studied through detailed experiments. It was found that iron improved the catalyst by regulating the degree of polymerization and the dispersion of Mn oxide species supported on the anatase surface, which was the key factor for both the SCR activity and the N2 selectivity. The increased NO conversion was caused by the higher Mn oxide dispersion, while selectivity evaluation showed that N2O formation on the MnOx/TiO2 catalyst was much higher than that on the iron-improved catalyst. Isotopic labelling experiments using 15NH3 with NO indicated that NH was the key species for N2O generation. NH was easily generated on MnOx/TiO2 without iron, which had a higher oxidability than the iron-improved catalyst, as identified by H2 temperature-programmed reduction experiments.

Fe3O4 micro-particles encapsulated within silica bearing an outer layer of ordered mesoporous mSiO2-Fe (Fe3O4@SiO2@mSiO2-Fe) were synthesized. The material was a magnetically separable catalyst for the oxidative cracking reaction of styrene to produce benzaldehyde selectively, which was a very important transformation from the industrial viewpoint. Characterizations showed that this material was formed by a typical core-shell structure with uniform hexagonal mesopores possessed high specific surface area. The unique material structure facilitated the adsorption and mass transport of the organic molecules over its surface and enhanced the durability of the materials. Notably, the catalyst allowed the utilization of air as partial oxidant so that the reaction could employ reduced amount of H2O2, leading to an even safer process from large-scale application viewpoint.

Unexpectedly, L-proline/piperidine was found to be a better recyclable catalyst system than L-proline or piperidine alone in the condensation of acetone to prepare mesityl oxide (MO), an important intermediate in the chemical industry. Binding the catalyst system onto polymer resin enhanced the MO selectivity and reduced the catalyst loss. The mechanism of the bi-component catalyst system was also studied through control reactions, as well as by dynamic calculations. The MO selectivity could reach 74.4% and its isolated yield could reach 73.9%, based on the consumed acetone. Although the result does not immediately meet the requirement of industrial production, this study provides a novel organocatalyst system, which might offer a potential alternative to traditional inorganic catalysts that can be used under mild and neutral conditions.

The structure and catalytic properties of Pd catalyst supported on the outer surface or inner surface of carbon nanotubes (CNTs) have been investigated by using various experimental techniques combined with acetylene selective hydrogenation tests. It has been shown that Pd/CNTs-out catalyst exhibits higher ethylene selectivity than Pd/CNTs-in catalyst for acetylene selective hydrogenation. The electron interaction between CNTs support and palladium particles is responsible for higher ethylene selectivity over Pd/CNTs-out catalyst. It is found that Pd/CNTs-out catalyst exhibits higher ethylene selectivity than Pd/CNTs-in catalyst for acetylene selective hydrogenation. The electron interaction between CNTs support and palladium particles is responsible for higher ethylene selectivity over Pd/CNTs-out catalyst.

Fischer–Tropsch synthesis (FTS) is a classical topic of great significance because of the approach of post-petroleum times. For decades, people have attempted to develop iron-based FTS catalysts with high selectivity for lower olefins. By means of the anchoring effect and the intrinsic basicity of nitrogen-doped carbon nanotubes (NCNTs), iron nanoparticles were conveniently immobilized on NCNTs without surface premodification. The so-constructed Fe/NCNTs catalyst presents superb catalytic performance in FTS with high selectivity for lower olefins of up to 46.7% as well as high activity and stability. The excellent performance is well-correlated with enhanced dissociative CO adsorption, inhibition of secondary hydrogenation of lower olefins, and promoted formation of the active phase of χ-Fe5C2. All of these merits result from participation of the nitrogen, as revealed by our experimental characterization. These results may lead to a new strategy for exploring advanced FTS catalysts with abundant N-doped c...

BiOI/ZnSn(OH)6 composite photocatalysts with different weight percents of BiOI were successfully synthesized by a facile and economical deposition method at 80 °C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and Brunauer–Emmett–Teller (BET) surface area measurements. Photocatalytic reforming of ethanol for H2 production and photocatalytic degradation of phenol over BiOI/ZnSn(OH)6 samples were investigated. The results showed that the BiOI/ZnSn(OH)6 photocatalysts exhibited a coexistence of both tetragonal BiOI and cubic perovskite ZnSn(OH)6 phases. With increasing BiOI content, the absorption intensity of BiOI/ZnSn(OH)6 increased in the 280–550 nm region and the absorption edge shifted significantly to longer wavelengths compared with that of pure ZnSn(OH)6. The 19.7% BiOI/ZnSn(OH)6 catalyst exhibited obviously higher photocatalytic activity as compared to either pure ZnSn(OH)6 or BiOI, which could be primarily attributed to the presence of intimate contacts between ZnSn(OH)6 and BiOI resulted in easier charge transfer and more efficient separation of electron–hole pairs. The photocatalytic mechanism of BiOI/ZnSn(OH)6 was discussed.

The mixed-phase TiO 2 photocatalysts with different anatase/rutile/brookite ratios and high specific surface area (157–218 m 2 /g) were prepared by hydrothermal method at 100 °C and the effect of rutile content in TiO 2 on the BET surface area, light absorption and separation efficiency of photogenerated charge carriers was studied and correlated to the photocatalytic activity of TiO 2 . Rutile content increased from 0% to 100% by increasing the amount of TiCl 4 in aqueous phase and the initial pH value of reaction solution played an important role in the phase composition of TiO 2 . The photocatalytic mechanism of mixed-phase TiO 2 was discussed.

The Cu 2+ –MCM-41 mesoporous materials with different loadings of copper species in the framework have been prepared by hydrothermal method and characterized by using various physico-chemical methods combined with the selective catalytic reduction of NO by NH 3 . It has been shown that the particle size of metallic copper formed after hydrogen reduction is much smaller than that in the supported catalysts prepared by impregnation method, and that the SCR activity of catalyst increases obviously with the increase of Cu content to 10 wt.% because of its higher dispersion of copper metal in the mesoporous catalyst even at higher Cu loading.

The effect of the dispersion state and surface properties of supported vanadia on the selective catalytic reduction (SCR) activity of NO over V2O5/TiO2 catalysts was studied by various experimental techniques. The experimental monolayer dispersion capacity of V2O5 on anatase (6.86 VOx/nm2) measured by XRD was almost the same as the concentration of surface vacant sites of anatase estimated by the incorporation model, and it was suggested that isolated vanadia species tend to be dispersed on adjacent octahedral vacant sites. An increase of the NO turnover frequency (TOF) at 300 °C to a maximum (8.3 × 103 s1) at a coverage near half a monolayer was related to the increase of the amount of weak acid sites (Bronsted acid site on each vanadium ion). The TOF decreased rapidly at high VOx coverages because of a decrease of the reducibility of vanadia species and a decrease of the ratio of exposed vanadia species on the surface. The Bronsted acid sites on bridging V–O(H)–V and terminal V–OH of polymeric vanadia species were all active sites in the SCR reaction. The SCR activity of the V2O5/TiO2 catalysts was related to the dispersion state, acidity, and reducibility of the vanadia species.

CSC (Chinese Scholar Council) [2009631048]; NSFC [20921120405, 21021002]; NSF [CHE-0923910]; DOE [DE-FG02-07ER15895]

The paper reports in situ surface enhanced Raman scattering (SERS) spectroelectrochemistry study of sulfur adsorption and electro-oxidation on highly roughened polycrystalline Pt surface. It is intended to address a specific question: Does the final chemical state of the adsorbed sulfur species depend on the initial chemical state of the sulfur in deposition sources? Three different sulfur deposition sources were used: Na2S solution, electrochemically reductive SO2 solution, and S0 suspension. In all cases, the same dominant vibrational band at 300 cm−1 was observed on the freshly prepared S-adsorbed Pt electrode, indicating the same chemical state of the adsorbed sulfur which was recently assigned as the Pt–S2−. Possible spill-over sulfur adsorption from the deposited solid polymeric S 8 0 was observed. Overall, this work yielded important information on sulfur adsorption and electro-oxidation on roughened, polycrystalline platinum surfaces and demonstrated clearly the applicability and usefulness of the in situ SERS spectroelectrochemistry in investigating the chemistry of sulfur adsorption/poisoning on platinum surfaces.

Deactivation of the supported V2O5/TiO2 catalysts due to deposition of alkali and alkaline earth metal salts in fly ashes is one of the most important problems in the selective catalytic reduction (SCR) of NOx by NH3. In this work, the poisoning effect of Na+ and Ca2+ ions doped on the V2O5/TiO2 catalysts for selective catalytic reduction of NO by NH3 has been studied. It has been shown that the Na+ and Ca2+ ions doped can poison the V2O5/TiO2 catalyst and the Na+ ions exhibit greater poisoning effect than Ca2+ ions. The NO rate constant k on the Na+-V2O5/TiO2 catalyst decreased very sharply from 97.1 to 35.0 cm3 g−1 s−1 with increasing Na/V molar ratio from 0.00 to 0.20. In comparison, k on the Ca2+-V2O5/TiO2 catalyst remained almost unchanged when Ca/V molar ratio was below 0.05. Further increasing Ca/V molar ratio to 0.20 resulted in an obvious decrease of k from 101.8 to 46.3 cm3 g−1 s−1. It was suggested that Na+ ions combined strongly with dispersed vanadia species, neutralized the Bronsted acid sites and reduced their reducibility. In comparison, Ca2+ ions slightly affected the Bronsted acid sites of catalyst. Besides, the dispersed vanadia species on the Ca2+-V2O5/TiO2 catalyst had higher reducibility than Na+-V2O5/TiO2 catalyst. The different poisoning effects of Na+ and Ca2+ ions doped on the V2O5/TiO2 catalyst were correlated not only to the surface acidity but also to the reducibility of catalyst.

Low temperature methanol synthesis is a promising technique for the practical methanol industry. New developments of a new kind of low temperature methanol synthesis were reviewed, including the effects of feed gas, reaction solvent, supercritical media and catalyst modification. The reaction mechanism and kinetics were also summarized primarily. Carbon dioxide played an important role in this new kind of low temperature methanol synthesis. It reacted with hydrogen adsorbed on catalyst surface to form HCOOM, an important reaction intermediate. Alcohol solvent in the low temperature methanol synthesis performed not only a media, but also a homogeneous catalyst. The reaction of the adsorbed formate species with alcohol on Cu/ZnO catalyst surface proceeded according to the Rideal mechanism rather than Langmuir–Hinshelwood mechanism to form alkyl formate. The formation of alkyl formate from alcohol solvent and hydrogenation of such an alkyl formate were the key steps in low temperature methanol synthesis reaction. These results provided new insights into low temperature methanol synthesis.

The structure and catalytic properties of PtSn catalyst supported on Al2O3-modified SBA-15 (Al2O3/SBA-15) have been studied by using various experimental techniques combined with propane dehydrogenation tests. It has been shown that the PtSn/Al2O3/SBA-15 catalyst exhibits higher activity than PtSn/SBA-15 catalyst and higher stability than conventional PtSn/γ-Al2O3 catalyst for propane dehydrogenation. The characterization results of the catalysts have revealed that on pure SBA-15 tin is easier to be reduced to metallic state due to weak interaction of Sn species with SBA-15 support, resulting in lower H2 uptake and thus lower catalytic activity of PtSn/SBA-15. Modifying the internal pores of SBA-15 by alumina can enhance the interaction between Sn and Al2O3/SBA-15 support, resulting in the increase of catalytic activity for propane dehydrogenation. Moreover, the PtSn/Al2O3/SBA-15 catalyst has larger bare fraction of Pt surface after coke deposition, leading to higher catalytic stability than the PtSn/γ-Al2O3 catalyst.

The properties of BiMo based catalysts with varied composition and structure for the direct selective oxidation of propane to acrolein were investigated. It has been seen by XRD, XPS, in situ FT-LRS, and ESR that propane is selectively oxidized to acrolein via propylene intermediate species. The lattice oxygen of the catalysts is the active oxygen species for the selective oxidation of propane to acrolein via propylene; the selectivity and yield of acrolein associate closely with the redox properties of Mo=O species while the activity of Mo=O correlates tightly with its coordinated circumstance. The selective activity of Mo=O is improved in a sequence of locations as distorted octahedral MoO6, corner shared octahedral in koechlinite structure, edge shared octahedral and tetrahedral MoO4 in distorted scheelite structure. The selectivity and yield of acrolein approached 45mol% and 13.5mol%, respectively, and the amount of lattice oxygen with selective oxidative activity amounted to 258 mol/g on the optimum catalyst.

The structure and catalytic properties of the supported Ni/γ-Al 2 O 3 catalyst prepared with different nickel salt precursors for hydrogenation of a-pinene have been studied using X-ray diffraction, UV–VIS diffuse reflectance spectroscopy, temperature-programmed reduction, CO chemisorption, and microreactor tests. It has been shown that the catalytic hydrogenation activity of the Ni/γ-Al 2 O 3 catalyst increases with increasing Ni loading, and the catalytic activity of the nickel acetate-derived Ni/γ-Al 2 O 3 catalyst is much higher than that of the nickel nitrate-derived catalyst. The catalyst characterization results indicate that the different catalytic hydrogenation activity of Ni/γ-Al 2 O 3 prepared with different nickel salt precursors is correlated to the different ratio of Ni 2+ ions in the tetrahedral and octahedral vacancies of γ-Al 2 O 3 and the different reduction degree of the NiO/γ-Al 2 O 3 precursors. When the nickel ion loading is far below the dispersion capacity, the supported nickel ions preferentially incorporate into the tetrahedral vacancies of γ-Al 2 O 3 . With increasing nickel loading, the ratio of Ni 2+ ions that incorporate into the octahedral vacancies of γ-Al 2 O 3 increases. The dispersion capacity of nickel ions on γ-Al 2 O 3 derived from nickel acetate is lower than that of the sample derived from nickel nitrate due to the greater shielding effect of acetate anions than nitrate anions. Moreover, the ratio of octahedral Ni 2+ to tetrahedral Ni 2+ on the nickel acetate-derived sample is higher than that on the nickel nitrate-derived sample because of the lower density of octahedral vacancies on γ-Al 2 O 3 . As octahedral Ni 2+ ions are easier to be reduced to the metallic state than tetrahedral Ni 2+ ions, the catalytic activity of the Ni/γ-Al 2 O 3 catalyst prepared with the nickel acetate precursor is much higher than that of the catalyst prepared with the nickel nitrate precursor with the same nickel loading.

We theoretically demonstrate that the two-dimensional porous C2N sheet exhibits an extremely high selectivity and large permeance in favour of H2 among other atmospheric gases. This experimentally available porous C2N is superior to traditional membranes, such as polymers and silica, and could have great potential for hydrogen separation.

The Fischer-Tropsch (FT) synthesis reaction was conducted using bimodal catalyst in a slurry phase reactor. The bimodal catalyst was prepared from a bimodal support which was tailor-made by introducing SiO2 sol directly into the large pores of a SiO2 gel pellet The bimodal catalyst exhibited significantly higher activity in the slurry-phase Fischer-Tropsch synthesis than in other unimodal catalysts. The support with a large surface area allowed a highly dispersed cobalt particle, and its large pore size improved the diffusion of reactants and products. The diffusion of reactants inside the catalyst pores was simulated, and the effects of pore structure and pore size on catalytic performances were consistent with the simulation results. © 2005 American Institute of Chemical Engineers AIChE J, 2005

In situ EPR investigation by using CO as probe molecules shows that even pre-reduced by H 2 at lower temperature results in SMSI for anatase titania supported palladium catalyst, but not for rutile titania supported palladium catalyst. The reason of the different behavior between rutile and anatase titania supported palladium catalyst is discussed. The very different catalytic properties between anatase and rutile titania supported palladium catalyst pre-reduced at lower temperature, and the rapid change of conversion and selectivity of titania supported palladium catalyst with the elevation of pre-reduction temperature further confirm the above-mentioned results.

In-situ DRIFTS was used to clarify the reaction mechanism of a new methanol synthesis method on a Cu/ZnO catalyst at low temperature from syngas containing CO2 using an ethanol promoter. The format...

The chemical state of adsorbed sulfur (S) on a Pt surface was identified and investigated by a combination of detailed electrochemical (EC) measurements, in situ surface enhanced Raman scattering (SERS) and ab initio density functional theory (DFT) calculations. The SERS data of the adsorbed S coupled with the DFT calculations provide the first convincing evidence showing that the adsorbed sulfur is in a sulfide (S2-) state.

A large electrocaloric effect (ECE) near room temperature is reported in Sn doped BaTiO3 ceramics. By tuning Ba(Ti1−xSnx)O3 compositions which also exhibit relaxor ferroelectric response to near the invariant critical point, the Ba(Ti1−xSnx)O3 bulk ceramics at x ∼ 0.12 exhibit a large EC coefficient (ΔT/ΔE =0.27*10−6K⋅mV−1) over a 50 K temperature range. In addition to that, the diffuse phase transition is successfully applied to broaden the EC peaks under low electric field. These properties added together indicate a general solution of the electrocaloric materials with high performance for practical cooling applications.

A catalyst in the form of a capsule catalyst was prepared by coating HZSM5 membrane on a preshaped Co/SiO2 catalyst pellet. The capsule catalyst with HZSM5 membrane exhibited excellent selectivity for light hydrocarbon synthesis, especially for isoparaffin synthesis from syngas (CO + H2). Long-chain hydrocarbon formation was totally suppressed by the zeolite membrane. The modification of membrane and core catalyst significantly improved the catalytic properties of these new kinds of capsule catalysts.

A catalyst in the form of capsule catalyst was prepared by coating HZSM5 membrane on a preshaped Co/SiO 2 catalyst pellet. The capsule catalyst with HZSM5 membrane exhibited excellent selectivity for light hydrocarbon synthesis, especially for isoparaffin synthesis from syngas (CO + H 2 ). Long chain hydrocarbon formation was totally suppressed by the zeolite membrane. The modification of membrane and core catalyst significantly improved the catalytic properties of these new kinds of capsule catalysts.

New insights into the formation chemistry of chalcogenate-protected metal nanoparticles (NPs) synthesized via the well-known Brust-Schiffrin two-phase method are presented here. On the basis of Raman, NMR, and surface plasmon resonance characterizations, it is concluded that, before the formation of any metal-chalcogen bonds, metal nucleation centers/NPs are first formed inside the inverse micelles of the tetrabutylammonium bromide in the organic solvent, where the metal ions are reduced by NaBH(4). The ensuing formation of the metal-chalcogen bonds between the naked metal NPs inside the micelles and the organo-chalcogen ligands in the organic solvent is the mechanism by which the further growth of the metal core can be controlled. This proposed mechanism is further examined in the formation of Ag and Cu NPs.

not Available.

The structure and catalytic properties of anatase and rutile supported manganese oxide catalysts prepared by impregnation method have been studied by using X-ray diffraction (XRD), laser Raman spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS), H(2) temperature-programmed reduction (H(2)-TPR) and BET surface area measurements combined with activity testing of selective catalytic reduction (SCR) of NO by NH(3). It has been shown that the manganese oxide loadings on the two TiO(2) supports exert great influences on the SCR activity. For the rutile supported manganese oxide catalysts, increasing manganese oxide loading leads to the increase of reducibility of dispersed manganese oxide species and the rate constant k, which reaches a maximum around 9.6 × 10(-6) mol g(Mn)(-1) s(-1) at 0.5 mmol Mn per 100 m(2) TiO(2). When the manganese oxide loading is beyond this value, the existence of amorphous MnO(x) multiple layers will certainly reduce the ratio of manganese oxide species exposed on the surface and the reducibility of dispersed manganese oxide species, resulting in the rapid decrease of rate constant k. The LRS and XPS results have revealed that for the anatase supported manganese oxide catalysts manganese oxide species exist in Mn(+4) as a major species with Mn(+3) species and partially undecomposed Mn-nitrate as the minor species. Under the SCR reaction conditions, Mn(+3) species on anatase are oxidized to Mn(+4) species, inserting in the surface of anatase and promoting the anatase-to-rutile transformation in the surface layers of the anatase support. Since these Mn(4+) cations are actually dispersed on the support with a rutile shell-anatase core structure and its concentration is very near to that of MnO(x)/TiO(2) (R) catalyst, the relation between the rate constant k and the MnO(x) loading on the anatase support is similar to that on the rutile support, and that the rate constant k values for anatase and rutile supported manganese oxide catalysts are very close at the same MnO(x) loading.

The dispersion state and catalytic properties of anatase-supported vanadia species are studied by means of X-ray diffraction (XRD), laser Raman spectroscopy (LRS), H2 temperature-programmed reduction (TPR) and the selective oxidation of o-xylene to phthalic anhydride. The almost identical values of the experimental dispersion capacity of V2O5 on anatase and the surface vacant sites available on the preferentially exposed (001) plane of anatase suggest that the highly dispersed vanadium cations are bonded to the vacant sites on the surface of anatase as derived by the incorporation model. When the loading amount of V2O5 is far below its dispersion capacity, the dispersed vanadia species might mainly consist of isolated VOx species bridging to the surface through V-O-Ti bonds. With the increase of V2O5 loading the isolated vanadia species interact with their nearest neighbors (either isolated or polymerized vanadia) through bridging V-O-V at the expenses of V-O-Ti bonds, resulting in the increase of the ratio of polymerized to isolated vanadia species and the decrease of the reactivity of the associated surface oxygen anions and, consequently, although the activity increases with loading to reach a maximum value, the turn over number (TON) of the V2O5/TiO2 catalyst decreases linearly. When the loading amount of V2O5 is higher than its dispersion capacity, the turn over number decreases more rapidly with the increase of V2O5 loading due to the formation of V2O5 crystallites in which the oxygen anions associated with V-O-V bonds are less reactive and only partially exposed on the surface.