Applied Catalysis A, General (v.451, #C)

Contents (iii-xi).

Dehydration of fructose to 5-hydroxymethylfurfural (HMF) in an aqueous acetonitrile biphasic system in the presence of acidic ionic liquids by Takashi Okano; Kun Qiao; Quanxi Bao; Daisuke Tomida; Hisahiro Hagiwara; Chiaki Yokoyama (1-5).
Display Omitted► A novel method is established to induce phase separation of water/acetonitrile by using an acidic ionic liquid. ► We report a novel and recyclable aqueous biphasic system for dehydration of fructose to HMF. ► The current system can afford a yield of HMF in organic phase as high as 88.7% at low reaction temperature. ► The potential of the current system is investigated by a 50-times-scale-up experiment.In this study, we report that phase separation of water/acetonitrile solution to a biphasic system can be induced by the presence of an acidic ionic liquid, i.e., 1-methyl-3-(butyl-4-chlorosulfonyl) imidazolium chlorosulfate ([MBCIm]SO3Cl), which allows to produce pseudo ternary phase of the/water/actonitrile/[MBCIm]SO3Cl system at room temperature. Based on this finding, an efficient and recyclable aqueous acetonitrile biphasic system is established for catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in the presence of [MBCIm]SO3Cl at low temperature in a shorter period of time. The ionic liquids remaining in the organic phase can be efficiently removed by simple treatment with alumina. This leaves only HMF, with a yield of up to 88.7%, in the acetonitrile phase, which could be easily removable.
Keywords: Acidic ionic liquids; HMF; Phase separation; Aqueous–organic biphasic system;

Biphasic single-reactor process for dehydration of xylose and hydrogenation of produced furfural by V.V. Ordomsky; J.C. Schouten; J. van der Schaaf; T.A. Nijhuis (6-13).
Display Omitted► Xylose dehydration to furfural with hydrogenation was studied in a biphasic process. ► Amberlyst-15 and Ru/C were localized in the aqueous and organic phases, respectively. ► The main product of combined process is tetrahydrofurfuryl alcohol. ► Suppression of xylose hydrogenation increases in the order 1-butanol < MTHF < cyclohexane. ► The selectivity to tetrahydrofurfuryl alcohol from xylose at 30% conversion was 50%.The processes of xylose dehydration and the consecutive furfural hydrogenation have been combined in a single biphasic reactor. The dehydration was studied over Amberlyst-15 and the hydrogenation over a hydrophobic Ru/C catalyst. 1-Butanol, 2-methyltetrahydrofuran and cyclohexane were used as solvents in the process. The hydrogenation catalyst in the reactor was present in the organic phase and the dehydration catalyst in the aqueous phase. An increase of the hydrophobicity of the solvent in the order 1-butanol < 2-methyltetrahydrofuran < cyclohexane suppressed the hydrogenation of xylose to xylitol due to a decrease of the xylose solubility, while forming furfural hydrogenation products. The main product is tetrahydrofurfuryl alcohol.
Keywords: Xylose dehydration; Furfural; Hydrogenation; Biphasic process;

Structural properties of alumina- and silica-supported Iridium catalysts and their behavior in the enantioselective hydrogenation of ethyl pyruvate by A.B. Dongil; B. Bachiller-Baeza; I. Rodríguez-Ramos; A. Guerrero-Ruiz; C. Mondelli; A. Baiker (14-20).
Display Omitted► Iridium catalysts were studied in the asymmetric hydrogenation of ethyl pyruvate. ► Iridium nanoparticles were prepared by impregnation or flame spray pyrolysis. ► Catalytic performance is influenced by particle size and morphology, and support. ► A correlation between enantioselectivity and the heat of CO adsorption was suggested.Iridium catalysts were prepared using alumina or silica as supports and two preparation methods, incipient wetness impregnation and flame spray pyrolysis. These catalysts were characterized, after reduction in hydrogen, by transmission electron microscopy, infrared spectroscopy of adsorbed CO and microcalorimetry of CO chemisorption. Aliquots of these catalysts were tested in the ethyl pyruvate hydrogenation using cinchonidine as a chiral modifier. Different enantioselectivities to (R)-ethyl lactate were obtained depending on the support material and the preparation method. Based on the structural characterization it is proposed that the different enantioselectivities are mainly due to different surface structure of the iridium nanoparticles caused by the support interaction.
Keywords: Ethyl pyruvate; Asymmetric hydrogenation; Iridium catalysts; Microcalorimetry;

Display Omitted► Pd-doped cobalt nanofibers were synthesized using simple and effective technique. ► New mechanism can be used to release hydrogen form ammonia borane; photohydrolysis. ► The stoichiometric hydrogen has been obtained within few minutes under the sunlight. ► The introduced nanofibers can be used as an effective photocatalyst.Due to the axial ratio feature, bimetallic nanofibers are expected to have novel characteristics. In this study, Pd-doped Co nanofibers could be successfully prepared using simple, low cost, high yield and effective technique; electrospinning. The introduced nanofibers have been synthesized by calcination of electrospun nanofibers composed of Pd NPs/cobalt acetate tetrahydrate/poly(vinyl alcohol) in a vacuum atmosphere. The utilized physicochemical characterizations indicated that the introduced bimetallic nanofibers are chemically protected by a sheath of graphite layer. Interestingly, the introduced nanofibers can be utilized in hydrolysis of ammonia borane in an aqueous solutions using two different simultaneous mechanisms; normal and photo catalysis. The solar radiation improves the performance as the stoichiometric hydrogen has been obtained within few minutes under the sunlight because of the photohydrolysis influence. Reusability is a distinct feature for the introduced nanofibers as they could be utilized for several successive times with the same efficiency. Moreover, due to the carbon sheathing, no metallic ions release was observed in the final solution. Photohydrolysis mechanism of ammonia borane might open a new avenue to utilize different class of materials to release the embedded hydrogen in the ammonia borane complex.
Keywords: Metallic nanofibers; Electrospinning; Pd-doped cobalt; Photohydrolysis; Ammonia borane;

Pd/CNT-promoted Cu―ZrO2/HZSM-5 hybrid catalysts for direct synthesis of DME from CO2/H2 by Meng-Hui Zhang; Zhi-Ming Liu; Guo-Dong Lin; Hong-Bin Zhang (28-35).
Display Omitted► Pd/CNTs doped CuZr/HZSM-5 shows high catalytic activity for direct DME-synthesis. ► Direct DME-synthesis from CO2/H2 markedly raises driving force of CO2 hydrogenation. ► “Stepwise precipitation–slurry mixing” is a good method to prepare hybrid catalyst.A type of bi-functional hybrid catalyst of Pd-decorated CNT-promoted Cu-ZrO2 admixed with HZSM-5 zeolite was developed, and displayed excellent performance for the direct synthesis of dimethyl ether (DME) from CO2/H2 via CH3OH in a single fixed-bed continuous flow reactor. Over a CuZr–PdCNTs/HZSM-5 hybrid catalyst under reaction conditions of 5.0 MPa, 523 K, V(H2)/V(CO2)/V(N2) = 69/23/8, GHSV = 25,000 mLSTP/(h g-hydr. catal.), the observed specific rate of CO2 hydrogenation-conversion reached 0.39 μmol/(s m2-Cu0-SA), which was 1.22 times that of the corresponding Pd/CNTs-free counterpart CuZr/HZSM-5. The addition of a minor amount of the Pd-decorated CNTs into the CuZr/HZSM-5 host catalyst caused little change in the apparent activation energy for CO2 hydrogenation, but led to an increase of metal Cu exposed area (catalytically active Cu surface-sites closely associated with the CO2 hydrogenation to methanol) and marked improvement of adsorption performance of the catalyst for H2 and CO2. The latter would help generate a micro-environment with higher concentration of active H and CO2 adspecies at the surface of the functioning catalyst, thus increasing the rate of the surface hydrogenation reactions. The present study also demonstrated that combining the methanol-synthesis and methanol-dehydration-to-DME processes in heterogeneous “one-pot” reactions by using the bi-functional hybrid catalyst could indeed enhance the driving force for CO2 hydrogenation conversion.
Keywords: Pd-decorated CNTs; Pd-decorated CNT-promoted Cu-ZrO2/HZSM-5 hybrid catalysts; CO2 hydrogenation; Direct DME synthesis;

Alkoxylation of camphene over silica-occluded tungstophosphoric acid by M. Caiado; A. Machado; R.N. Santos; I. Matos; I.M. Fonseca; A.M. Ramos; J. Vital; A.A. Valente; J.E. Castanheiro (36-42).
Display Omitted► Alkoxylation of camphene was studied in the presence of H3PW12O40 on silica. ► Catalytic activity decreases with the increases of chain length of the alcohols. ► High selectivity of PW-Ssg catalyst to alkyl isobornyl ether was observed. ► The PW-Ssg sample can be reused without loss of activity and selectivity.Silica-occluded tungstophosphoric acid (PW-Ssg) was used as an efficient, environmentally friendly heterogeneous catalyst for the liquid-phase alkoxylation of camphene into their more valuable alkyl isobornyl ether, which is used as perfume and cosmetic products, in the pharmaceutical industry, as well as in the food industry. The alkoxylation of camphene with C1–C4 alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol) to alkyl isobornyl ether was studied in the presence of PW-Ssg (4.2% w/w) at 60–80 °C. Different linear and branched alcohols are compared in relation to their activity for the alkoxylation of camphene. The catalytic activity decreased with the increase of number of carbon atoms in the chain alcohol, which can be explained due to the presence of sterical hindrance and diffusion limitations inside the porous system of the catalyst. High selectivity of PW-Ssg catalyst for the alkyl isobornyl ether was observed. The effect of various parameters, such as catalysts loading, initial concentration of camphene and temperature were studied to optimise the ethoxylation of camphene. The catalytic stability of PW-Ssg in the ethoxylation of camphene was studied by performing consecutive batch runs with the same catalyst sample at the same conditions. After the third run, the catalytic activity stabilized. The catalyst can be recovered and reused without significant leaching of PW. The catalytic activity of PW-Ssg was compared with the activity of tungstophosphoric acid immobilized on silica by impregnation method (PW-Sim). The activity of PW-Ssg is higher than that of PW-Sim catalyst. After reaction, the PW-Sim sample lost 20% of its heteropolyacid.
Keywords: Camphene; Alkoxylation; Heteropolyacid; Silica;

Carbon dioxide reforming of methane to synthesis gas over a TiO2–Ni inverse catalyst by Hyun Ook Seo; Jong Ki Sim; Kwang-Dae Kim; Young Dok Kim; Dong Chan Lim; Sang Hoon Kim (43-49).
Display Omitted► TiO2–Ni inverse catalysts were prepared using atomic layer deposition. ► TiO2–Ni inverse catalysts for carbon dioxide reforming of methane reaction. ► High reactivity and stability of TiO2–Ni inverse catalysts. ► Evidence for actual role of TiO2–Ni interface was provided. ► Decoration effect of metal oxide particles was suggested.TiO2–Ni inverse catalysts were prepared using an atomic layer deposition (ALD) process, and catalytic CO2 reforming of methane (CRM) reactions over the catalysts (either bare Ni or TiO2 coated-Ni particles) were performed using a continuous flow reactor at 800 °C. The TiO2–Ni inverse catalyst had a higher catalytic reactivity at the initial stage of the CRM reaction at 800 °C compared to that of bare Ni catalysts. Moreover, the high activity of the TiO2–Ni catalyst was maintained over 65 h of the CRM reaction at 800 °C, whereas deactivation of the bare Ni surface began within 1 h under the same conditions. Surface analysis using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy showed that deposition of graphitic carbon was effectively suppressed in the presence of TiO2 nanoparticles on the Ni surface, thereby improving the catalytic activity and stability of the TiO2–Ni catalytic system. We suggest that utilizing the decorative effect of oxide nanoparticles on the surface of metal catalyst has great potential for the development of metal-based catalysts with high stability and reactivity.
Keywords: CO2 reforming of methane; Hydrogen; Ni; Inverse catalyst; TiO2;

The Cs x H3 −  x PW12O40 catalysts microstructure model by V.Z. Sasca; O. Verdes; L. Avram; A. Popa; A. Erdőhelyi; A. Oszko (50-57).
Display Omitted► The heteropoly compounds of Cs x H3 −  x PW12O40 type were prepared and characterized. ► Ethanol conversion by pulse reaction technique was used for catalytic tests. ► The formation of strong adsorbed species on catalysts was evidenced. ► A microstructure model of the Cs x H3 −  x PW12O40 is proposed. ► The model explains the specific surface area and the selectivity variation.The salts of the H3PW12O40 (H3PW) with Cs counter cation were prepared and characterized by thermal analysis, IR, XRD, BET, XPS LEIS and SEM methods. The samples are denoted as Cs x H3 −  x PW12O40 (x  = 1, 2, 2.25, 2.5 and 3). The catalytic activity of the compounds prepared with various cesium/Keggin unit ratios was tested in ethanol conversion by pulse reaction technique. The change of catalytic activity vs. pulse number was explained by formation of strong adsorbed species on catalysts. A microstructure model of the Cs x H3 −  x PW12O40 containing spherical aggregates, which consist of Cs3PW12O40 crystallites core coated with H3PW12O40 layers, was proposed on the basis of the structural–textural properties and their catalytic performances in ethanol conversion. The model explains the abrupt increase of the specific surface area for x  > 2 and also the highest selectivity for C4 hydrocarbons on Cs2.5H0.5PW12O40 due to its special microstructure: a H3PW monolayer embedding a core of Cs3PW. The Cs concentrations on the Cs x H3 −  x PW12O40 surface were determined by XPS and were found less than expected based on their chemical composition, but which correspond to the proposed model of microstructure.
Keywords: Heteropoly compounds; Cesium tungstophosphates; Keggin structure; Ethanol conversion; Microstructure model; XPS measurements;

Aerobic diol lactonization by Au-nanoparticles supported onto an anion-exchange resin by Werner Oberhauser; Alessandro Lavacchi; Francesco Vizza; Laura Capozzoli; Hon Man Lee (58-64).
Display Omitted► Simple synthesis of Au-nanoparticles on an anion-exchange resin. ► Aerobic oxidation of diols to lactones by Au-nanoparticles. ► Influence of the resin counter-anion on the catalytic activity of Au-nanoparticles. ► Conversion of aliphatic diols into the dicarboxylic acid.Different amounts of AuCl4 (i.e. 3.0, 0.5 and 0.1 wt% of Au) were supported onto the anion-exchange resin Dowex Marathon MSA in its chloride form. A successive rapid reduction of the latter anchored Au-compound with NaBH4 combined with anion exchange reactions (i.e. replacement of chloride by acetate or carbonate) gave resin-stabilized Au-nanoparticles (NPs) of comparable size and size distribution. A screening of the catalytic performance of the obtained heterogenous catalysts in the aerobic oxidation reaction of selected diols to lactones in toluene revealed the carbonate form of the resin bearing 0.1 wt% of Au to be the most active catalytic system. The aerobic oxidation of aliphatic diols led to the formation of the corresponding dicarboxylic acid as side-product, which deactivates the catalyst. By washing the deactivated catalyst after each cycle with a solution of Na2CO3 in water restored the initial catalyst performance for at least four consecutive catalytic cycles.
Keywords: Au-nanoparticles; Anion-exchange resin; Aerobic diol lactonization;

Display Omitted► Doping with ceria on SP (500) results in an increase in S BET and pore volume. ► Ceria can greatly improve the oxidation properties of Pd/SP (500). ► Pd/6%Ce/SP (500) exhibits the highest catalytic activity for benzene oxidation.Pearl shells are the main waste of the pearl industry, which discards millions of tons of pearl shells each year in China. To date, the use of pearl shells in the complete oxidation of volatile organic compounds (VOCs) has not been reported. In this paper, shell powder (SP) was used as a carrier for ceria and Pd catalysts for the complete oxidation of benzene. The influence of the ceria promoter on the texture/structure and catalytic performance of Pd/SP was investigated. The results show that adding ceria into the SP support increased the BET surface area and total pore volume and decreased the sinterability of SP. The catalytic activity and H2 temperature-programmed reduction (H2-TPR) results show that adding ceria can greatly improve the oxidation properties of Pd/SP catalysts and enhance the catalytic activity for the complete oxidation of benzene. The improvement in the catalytic activity is mainly due to the optimization of the catalyst texture/structure and redox properties by the strong interaction of Pd and ceria and the addition of ceria.
Keywords: Shell powder; Ceria; Pd; Benzene oxidation;

Display Omitted► Sulfated zirconia is an efficient catalyst for Prins cyclization of styrene with paraformaldehyde. ► Influence of sulfur content and acidity of sulfated zirconia catalyst on activity and selectivity. ► The efficiency of catalyst for Prins cyclization of different alkenes with paraformaldehyde. ► Understanding the solvent effect in terms of dielectric constant, acceptor and donor numbers.Prins cyclization of styrene with paraformaldehyde was carried out over sulfated zirconia (SZ) catalyst in liquid phase. The SZ catalysts were synthesized by precipitation method with different sulfur impregnation and characterized by XRD, FT-IR, Nitrogen sorption, NH3-TPD. The SZ showed best performance among different types of acid catalysts. The acidity of SZ optimized by different concentrations of H2SO4 treatment influences the selectivity for dioxane. The sulfur loading, nature of solvent, temperature, catalyst amount, mole ratio and reusability of catalyst were investigated. The SZ catalyst synthesized by impregnating 2N sulfuric acid was found to be highly selective for the synthesis of 4-phenyl-1,3-dioxane (93%) with almost complete conversion of styrene (∼100%). The catalyst was recycled thrice with negligible decrease in the yield of 4-phenyl-1,3-dioxane.
Keywords: Prins cyclization; Sulfated zirconia; Styrene; Paraformaldehyde; 1,3-Dioxane;

A density functional theory study of CO oxidation on Pd-Ni alloy with sandwich structure by Freda C.H. Lim; Jia Zhang; Hongmei Jin; Michael B. Sullivan; Ping Wu (79-85).
Display Omitted► We demonstrated a dependency of catalytic properties to the Ni occupancy site in an alloy. ► Our results show that optimal compressive strain lowers the reaction barrier. ► A compressive strain beyond 7% induces a distortion that eliminates the adsorption. ► We propose that the Pd-Ni-Pd surface sandwich alloy is a good catalyst for CO oxidation reaction. ► This work will guide experimentalists in ways to improve the catalysts with a cheap metal.Density functional theory calculations are performed to study CO oxidations on pure Pd(1 1 1) surface as well as on its Ni alloy nanostructures. Our calculations demonstrate a dependency of catalytic properties to the Ni occupancy site in the alloys. Furthermore, our results also show that optimal compressive strain (around 5%) of the alloy maybe beneficial to lower the reaction barrier and a compressive strain beyond 7% induces a distortion on the surface that eliminate the adsorption site for the reacting species. Based on our results, we propose that the Pd-Ni alloy with sandwich structure could be a potential candidate identified for lowering the cost of Pd alloys in the catalysis of the CO oxidation reaction. This new structure illustrates a potential lowering in the CO oxidation barrier. Furthermore, our results also indicate that the partial replacement of cheaper Ni into the Pd catalyst should not adversely affect the catalytic property.
Keywords: CO oxidation; Bimetallic alloy; Pd alloy; Pd-Ni; Sandwich structure; Heterogeneous catalysis;

Display Omitted► Ceria catalyzed acetic acid ketonization in the condensed phase. ► Ceria calcination temperature influenced the ketonization reaction. ► Bulk and surface routes are likely proceeding through the same mechanism.The ketonization of carboxylic acids is an attractive method of removing undesirable acidity and oxygen from precursors to biorenewable fuels. However, to be more industrially relevant the ketonization reaction temperature needs to be lowered. Unfortunately, ketonization is not fully understood making this task more challenging. In this work, it was found that the calcination temperature changes the type of interactions that a good ketonization catalyst, cerium oxide, has with the model biomass bio-oil compound acetic acid. Through extensive pre- and post reaction characterization the calcination temperature is determined to influence catalyst final morphology, crystallinity, and oxidation state. Differences in acid, base and redox properties for the ceria calcined at different temperatures did not correlate with the catalytic performance. The crystallinity of the starting ceria, as controlled by the calcinations temperature, was found to dictate whether the reaction proceeds through a bulk or a surface catalyzed mechanism.
Keywords: Ketonization; Ceria; Acetic acid; Bio-oil; Cerium acetate;

Cu on porous glass: An easily recyclable catalyst for the microwave-assisted azide–alkyne cycloaddition in water by Katharina Jacob; Achim Stolle; Bernd Ondruschka; Klaus D. Jandt; Thomas F. Keller (94-100).
Display Omitted► Loading of porous glasses with Cu led to catalysts with high activity in CuAAC. ► The active specie is Cu(I) or Cu(0) formed by reduction with sodium ascorbate. ► Catalyst characterization with SEM identifies Cu-agglomerates at the glass surface. ► Cu/porous glass materials can be reused up to 5 times without decrease of activity. ► Catalysts revealed high stereoselectivity forming the 1,4-triazole mostly >99%.The propagation of the Click-reaction concept in synthetic chemistry, particularly the Cu-catalyzed cycloaddition between azides and alkynes, led to numerous applications in materials science, bio-, medicinal, and polymer chemistry. Often copper salts or complexes are applied as catalysts. In the present case those have been replaced by heterogeneous catalysts using porous glasses as support materials. Loading the supports with Cu using wet-impregnation technique led to Cu-loadings of 80% on theoretical basis, whereas other support materials revealed lower metal loads. Characterization of the catalyst morphology by SEM identified Cu-agglomerates at the surface. A 2 eV-shift of the binding energy of the Cu 2p core levels in the catalysts’ XPS spectra and the disappearance of satellite peaks led to the assumption that reduction of Cu(II) to Cu(I) or Cu(0) occurred during catalyst application. Indeed, working without a reducing agent (sodium ascorbate) resulted in decreased catalyst activity regarding the model reaction. The microwave-assisted cycloaddition of benzyl azide with phenylacetylene in water led to full conversion after 10 or 20 min at 120 or 100 °C, respectively. Reaction is characterized by excellent regioselectivity forming the 1,4-triazole almost exclusively. Optimization of the reaction conditions with respect to time and catalyst loading affords maximal TOF >635 h−1. Recycling studies revealed that up to four reapplications of the catalyst are possible without lost of activity.
Keywords: Azide; Alkyne; Porous glass; Microwave; XPS;

Solvent-free Ru-catalyzed isomerization of allyloxyalcohols: Methods for highly selective synthesis of 1-propenyloxyalcohols by Magdalena Urbala; Stanisław Krompiec; Mateusz Penkala; Witold Danikiewicz; Małgorzata Grela (101-111).
Display Omitted► The soluble ruthenium complexes were tested as pre-catalysts. ► Solvent-free highly selective synthesis of terminal 1-propenyloxyalcohols was studied. ► An easy scale-up with the practically quantitative yields of product can be applied. ► Distillation of product from above catalyst was a highly efficient purification method. ► Pathways of Ru-catalyzed transformations of hydroxyalkyl allyl ethers were presented.An excellent, selective and very convenient method for the synthesis of hydroxyalkyl vinyl ethers of HO–A–O–CH=CHCH3 type via isomerization of appropriate readily available allylic substrate of HO–A–O–CH2CH=CH2 type mediated by various soluble ruthenium complexes under solvent-free conditions has been presented. Our research has demonstrated that (CH2) n or (CH2CH2O) n or ortho-phenylene, but neither –CH2CCCH2– nor –CH2CH=CHCH2– can play a role of an A linker. The use of detailed screening experiments allowed discovering new, efficient catalysts for a highly selective isomerization of allyloxyalcohols such as [RuH2(CO)(PPh3)3], [RuH2(PPh3)4] or [Ru(CO)3(PPh3)2]. For these ruthenium complexes, the only reaction products were enol ethers, and an intra- and/or intermolecular addition of an OH group to the double bond has not been observed. The use of the complexes containing Cl ligand as catalysts precursors ([RuClH(CO)(PPh3)3], [RuCl2(PPh3)3], RuCl3·3H2O and other) and surprisingly also [Ru3(CO)12] led to a consequent cyclization and/or polymerization of enol ethers. The addition to the catalytic system of trialkyl amines, K2CO3, CaH2 and others as scavengers of HCl (generated in situ from Ru–Cl complexes) has also allowed to eliminate fully consequent reactions. The scale-up of the selected method of isomerization has been successfully performed and the best results were obtained for [RuH2(CO)(PPh3)3] and [RuCl2(PPh3)3] + 5 K2CO3. Finally, several pathways of the reaction between allyloxyalcohols and the ruthenium complexes of various structures have been proposed. The double bond migration and addition of the OH group to the allyl or the vinyl ether moiety could proceed according to the transition metal catalysis mechanisms and tandems the transition metal catalysis-Lewis acid catalysis or the transition metal catalysis-Brønsted acid catalysis.
Keywords: Allyl ethers; Isomerization; Ruthenium complexes; 1-Propenyl ethers; Vinyl ethers;

A facile one-pot synthesis of hierarchically porous Cu(I)-ZSM-5 for radicals-involved oxidation of cyclohexane by Xiaoxia Zhou; Hangrong Chen; Xiangzhi Cui; Zile Hua; Yu Chen; Yan Zhu; Yudian Song; Yun Gong; Jianlin Shi (112-119).
Display Omitted► Mesoporous Cu-ZSM-5 synthesized by a one-pot hydrothermal process. ► Mesoporous Cu-ZSM-5 has a superior hierarchically pores structure. ► Mesoporous Cu-ZSM-5 has a highly dispersed framework Cu(II)/Cu(I). ► The sample shows an excellent catalytic performance for cyclohexane oxidation. ► The outstanding catalysis depends on the uniformly dispersed framework Cu(II)/Cu(I).An extraordinarily high catalytic performance of up to 28% cyclohexane conversion and above 93% selectivity for cyclohexanone and cyclohexanol in the cyclohexane oxidation has been achieved under mild conditions by using copper-doped hierarchically micro/mesoporous zeolite ZSM-5, which has been fabricated by a facile one-pot hydrothermal synthetic process at a relatively low hydrolysis temperature. The excellent catalytic activity was ascribed to the highly dispersed framework copper ions (Cu+/Cu2+) as catalytic active sites and the hierarchically porous structure to provide the fast diffusion pathway for reactant/product molecules. The presence of the framework Cu(I) was proposed to promote the decomposition of H2O2 and the formation of radicals HO, and thus accelerate the selective oxidation of cyclohexane. More importantly, the synthesized catalyst showed excellent recyclable properties, demonstrating the high catalytic stability and future application prospect of such hierarchical heterogeneous catalysts in chemical industry.
Keywords: Hierarchical porous structure; ZSM-5; Cu(I); Cyclohexane; Radical;

Study of adsorption-assisted photocatalytic oxidation of benzene with TiO2/SiO2 nanocomposites by Zhi Liu; Feitai Chen; Pengfei Fang; Shaojie Wang; Yuanpeng Gao; Feng Zheng; Yang Liu; Yiqun Dai (120-126).
.Display Omitted► Highly distributed TiO2/SiO2 composites were prepared via a simple reflux-stir process. ► The composites show superior photocatalytic oxidation efficiency and recyclability. ► Different Ti/Si molar ratios of TiO2/SiO2 influence the photocatalytic activity greatly. ► Enhanced adsorptive power to water vapor and benzene accelerate the reaction rate. ► A high population of surface hydroxyl groups leads to the notable photoactivity.TiO2/SiO2 composite photocatalysts were prepared via a simple reflux-stir process. These composites exhibit a highly distributed state between TiO2 (P25) and fumed silica (SiO2) nanoparticles, and the SiO2 nanoparticles surround the TiO2 crystalline grains closely. The photoactivity of the composites was investigated by photocatalytic oxidation of gaseous benzene. By adjusting the Ti/Si mole ratio from 50:1 to 1:1, the photocatalytic efficiency of the TiO2/SiO2 composites ascends firstly and then decreases. The optimum Ti/Si mole ratio is 30:1, and the photocatalytic efficiency reaches 92.3% within 120 min, which is 6.8 times higher than that of P25. Additionally, recycled tests which performed ten times demonstrate the nanocomposites possess a pretty good recyclability. The excellent photocatalytic performances can be chiefly attributed to the good dispersion state between TiO2 and SiO2. The special structure helps the formation of a high population of hydroxyl groups on the catalysts surface, and these hydroxyl groups greatly improve the charge separation efficiency and the reaction rate. In addition, the enhanced adsorption powers to water vapor and benzene also contribute to the high photoactivity.
Keywords: TiO2; SiO2; Adsorption; Benzene; Hydroxyl radicals;

Esterification of acrylic acid with 2-ethylhexan-1-ol: Thermodynamic and kinetic study by Tomasz Komoń; Piotr Niewiadomski; Paweł Oracz; Małgorzata E. Jamróz (127-136).
.Display Omitted► Among studied catalysts, Amberlyst 70 showed the most catalytic activity. ► The temperature dependence of the thermodynamic equilibrium constant was determined. ► The enthalpy of reaction was estimated. ► Kinetic model of the reaction was established. ► The kinetic parameters were found for ideal and non-ideal quasi-homogeneous models.The activity and selectivity of polystyrene sulfonic acid resins (Amberlyst 39, Amberlyst 46, Amberlyst 70, and Amberlyst 131) were measured in the reaction of 2-ethylhexyl acrylate formation. The kinetics of the esterification of acrylic acid with 2-ethylhexan-1-ol was studied using Amberlyst 70 ion exchange resin (1–10 wt%) as a catalyst superior over a group of commercial catalysts. The 7:1, 5:1, 3:1, 1:1, 1:3, 1:5, and 1:7 alcohol to acid molar ratio was used to carry out the reaction in an isothermal batch reactor at temperatures from 353 to 393 K. The studied mixtures are highly non-ideal, therefore, the kinetic equations and equilibrium parameters were expressed in terms of activities.
Keywords: Acrylic acid; 2-Ethylhexan-1-ol; Esterification; Kinetic; Ion exchange resin;

Nanocrystalline gold supported on NaY as catalyst for the direct oxidation of primary alcohol to carboxylic acid with molecular oxygen in water by Lipeng Zhou; Wenjun Yu; Lin Wu; Zhen Liu; Haijun Chen; Xiaomei Yang; Yunlai Su; Jie Xu (137-143).
Display Omitted► Au/NaY showed high catalytic activity for the oxidation of primary alcohol to acid. ► Pretreatment of NaY before loading of Au was essential. ► Preparation conditions affected loading amount, particle size and morphology of Au. ► These parameters determined the catalytic activity of Au/NaY. ► The catalyst was recyclable.Au/NaY was prepared by deposition–precipitation (DP) method using HAuCl4 as gold source. The samples were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy and inductively coupled plasma atomic emission spectrometry. It was found that the adjustment of the surface acidity of NaY, the pH and concentration of HAuCl4 solution, and the temperature and time for DP affected the particle size, the loading and the morphology of Au on NaY. The catalytic performance of Au/NaY was studied in the oxidation of alcohols to the corresponding carboxylic acids with molecular oxygen as oxidant under basic conditions. About 100% conversion of benzyl alcohol with 95.2% isolated yield of benzoic acid was obtained at the reaction temperature of 80 °C for 8 h. The catalyst was recycled for four times without loss of catalytic activity. In addition, the catalyst worked well for the catalytic oxidation of various alcohols including aromatic and aliphatic alcohols to the corresponding carboxyl acids.
Keywords: Au/NaY; Oxidation; Alcohol; Carboxylic acid;

Aqueous biphasic hydrogenations catalyzed by new biogenerated Pd-polysaccharide species by Stefano Paganelli; Oreste Piccolo; Franco Baldi; Riccardo Tassini; Michele Gallo; Giorgio La Sorella (144-152).
Display Omitted► Pd-EPS was prepared by Klebsiella oxytoca fermentation in the presence of Pd(NO3)2. ► Activated Pd-EPS was obtained by hydrogen treatment of Pd-EPS. ► Both palladium catalysts were active only in the presence of water. ► Both catalysts were easily recovered and reused in recycling experiments.A palladium species bound to an exopolysaccharide (Pd-EPS) was obtained from alive bacterial cells of Klebsiella oxytoca BAS-10 grown in static mode in the presence of Pd(NO3)2. Pd-EPS, after isolation and purification, was used as catalyst in the aqueous biphasic hydrogenation either of unfunctionalyzed olefins, as styrene, 1-octene and 1,3-diisopropenylbenzene, or of some α,β-unsaturated aldehydes. The catalytic system was very active under mild reaction conditions and its activity was maintained in some recycle experiments. Even more efficient was the “activated Pd-EPS”, obtained by a pre-treatment of Pd-EPS with 1 MPa of H2 at 30 °C for 21 h; while Pd-EPS originally contains only Pd(II), as demonstrated by XPS measurements, the activated catalyst shows the presence of both Pd(II) and Pd(0) in the ratio 1.9/1. The two catalytic systems show different structures at TEM observations evidencing the transformation of electron ultradense nanoaggregates (Pd-EPS) into jagged microaggregates (“activated Pd-EPS”).
Keywords: Palladium; Biphasic hydrogenation; Catalyst; Klebsiella oxytoca; Polysaccharide;

Hydroconversion of liquid hydrocarbons in a staged autothermal reactor by Samuel D. Blass; Aditya Bhan; Lanny D. Schmidt (153-159).
Display Omitted► Catalytic partial oxidation and hydroprocessing combined in an autothermal reactor. ► Wide range of conversions and product distributions observed. ► Higher aromatics yield from 2-decanone reaction than from decane or hexane.An autothermal staged reactor was assembled containing a top stage of Rh-Ce/α-Al2O3 which generated heat and H2 by reacting CH4 and air that passed through a downstream stage containing 0.5 wt% Pt/γ-Al2O3 mixed with either HBEA, HZSM-5, or USY in a heat-integrated non-isothermal reactor. The H2 produced subsequently reacts in a 20:1 ratio with a co-feed of hexane or decane or 2-decanone fed to the reactor between the stages. The large-sized pores of HBEA and USY allowed deoxygenation of 2-decanone to form decene isomers which can crack or cyclize to form up to a 36% yield of methylated and ethylated monoaromatics. The medium-sized pores of HZSM-5 restricted decene formation from 2-decanone by catalyzing cracking reactions to C2−6 compounds which can cyclize to form aromatics. By contrast, the reactor effluent from non-oxygenated reactants decane and hexane contained less than 5% aromatics. Thus, we extend the scope of staged autothermal reactor functionality to hydrocracking and hydroisomerization of higher saturated and oxygenated hydrocarbons.
Keywords: Autothermal; Staged reactor; Hydrocracking; Hydroisomerization;

Steam reforming of toluene over perovskite-supported Ni catalysts by Yasushi Sekine; Daiki Mukai; Yuki Murai; Satoshi Tochiya; Yoshiyuki Izutsu; Kei Sekiguchi; Naomi Hosomura; Hirohisa Arai; Eiichi Kikuchi; Yukihiro Sugiura (160-167).
Display Omitted► Steam reforming of toluene as a model of aromatic hydrocarbon for hydrogen production. ► Ni/La0.7Sr0.3AlO3−δ catalyst showed very high activity and stability, low coke-formation. ► Substituting Sr had a strong promotion effect, but impregnating Sr showed no promotion effect. ► Transient response tests using isotope revealed the lattice oxygen played an important role.Hydrogen production by steam reforming of toluene as a model aromatic hydrocarbon has been investigated with various Ni/perovskite catalysts. Among them, Ni/LaAlO3 catalyst showed high catalytic activity. Partial substitution of the La site of LaAlO3 support with other elements (Sr, Ba or Ca) was conducted for the Ni/LaAlO3 catalyst, and substitution with 30% Sr promoted catalytic activity and selectivity to hydrogen. Optimization for the Ni loading amount over Ni/La0.7Sr0.3AlO3−δ catalyst revealed that 5 wt% Ni/La0.7Sr0.3AlO3−δ had the highest toluene conversion and the smallest amount of carbon deposition. To elucidate the role of doped Sr, the catalytic natures of Sr-substituted catalyst Ni/La0.7Sr0.3AlO3−δ and Sr-supported catalyst Ni/Sr/LaAlO3 were compared. Results show that Sr-ions should be incorporated in the LaAlO3 perovskite structure to show high catalytic performance. Based on results of transient response test with H2 18O on Ni/La0.7Sr0.3AlO3−δ , Ni/Sr/LaAlO3, and Ni/LaAlO3 at reaction temperature of 873 K, the formation of 18O-products was observed only on Ni/La0.7Sr0.3AlO3−δ catalyst derived from redox between the lattice oxygen in the perovskite and water. Lattice oxygen in the La0.7Sr0.3AlO3−δ support worked as active oxygen species to enhance its catalytic nature.
Keywords: Steam reforming; Hydrogen production; Perovskite oxide; Lattice oxygen; Coke-formation;

Diallyldimethylammonium and trimethylvinylammonium ionic liquids—Synthesis and application to catalysis by Hieronim Maciejewski; Karol Szubert; Ryszard Fiedorow; Rafał Giszter; Michał Niemczak; Juliusz Pernak; Witold Klimas (168-175).
Display Omitted► Unsaturated substituent-containing ammonium ionic liquids were synthesized. ► Rhodium and platinum complexes were immobilized in ammonium ionic liquids. ► A very efficient catalytic system for hydrosilylation was developed. ► TON as high as 98,200 was obtained. ► Multiple use of catalyst without activity decrease was achieved.New quaternary ammonium salts containing unsaturated substituents (allyl or vinyl) were synthesized. All of them were subjected to spectroscopic, elemental and thermogravimetric analyses. The above compounds are ionic liquids (T m  < 100 °C) and were applied to immobilization of three rhodium(I) complexes [Rh(PPh3)3Cl], [{Rh(μ-Cl)(cod)}2] and [{Rh(μ-OSiMe3)(cod)}2] as well as three platinum complexes at different oxidation states [Pt(PPh3)4], K2[PtCl4] and K2[PtCl6]. Homogeneous catalytic systems were obtained and employed in the biphasic process of hydrosilylation of octene and allyl glycidyl ether with 1,1,1,3,5,5,5-heptamethyltrisiloxane. Catalytic activities of all the systems were compared and the best one was selected. The latter made it possible to recycle 10 times the same catalyst sample without a decrease in its activity and to easy separate the catalyst from the post-reaction mixture by decantation. The developed system is one of the most effective catalytic systems for hydrosilylation known to date.
Keywords: Ionic liquids; Quaternary ammonium salts; Immobilization; Rhodium and platinum complexes; Biphasic hydrosilylation;

Effect of surface Lewis acidity on selective catalytic reduction of NO by C3H6 over calcined hydrotalcite by Deling Yuan; Xinyong Li; Qidong Zhao; Jijun Zhao; Shaomin Liu; Moses Tadé (176-183).
.Display Omitted► Calcined hydrotalcite prepared by four methods to obtain various Lewis acid sites. ► Lewis acid sites changed with transformation from mixed oxides to spinel phase. ► Various nitrate species as the key intermediates form at different Lewis acid sites. ► Lewis acid sites play an important role in SCR by C3H6 over calcined hydrotalcite.The selective catalytic reduction (SCR) of NO by C3H6 has been studied over a series of calcined hydrotalcite, which were prepared by four different methods to obtain various Lewis acid sites. The catalysts have been investigated by X-ray powder diffractometer, N2 adsorption, Temperature-programmed desorption of NH3 (NH3-TPD), pyridine adsorption FTIR (Py-FTIR), Temperature-programmed desorption of NO + O2 (NO + O2-TPD) and in situ FTIR techniques. The Lewis acid sites could be changed with the transformation of the crystalline structure from the mixed oxides of MgO and Al2O3 to spinel phase. It is demonstrated that Lewis acid sites play an important role in determining the catalytic performance of SCR by C3H6 over calcined hydrotalcite catalysts. Various nitrate species as the key intermediate species for SCR could form at Lewis acid sites during the process of the reaction under lean-burn condition.
Keywords: Lewis acidity; Hydrotalcite; Temperature-programmed desorption; In situ FTIR;

Highly active copper catalyst for low-temperature water-gas shift reaction prepared via a Cu-Mn spinel oxide precursor by T. Tabakova; V. Idakiev; G. Avgouropoulos; J. Papavasiliou; M. Manzoli; F. Boccuzzi; T. Ioannides (184-191).
Display Omitted► Cu-Mn spinel oxides were synthesized via combustion and coprecipitation methods. ► Highly dispersed Cu0 sites are created from reduction/decomposition of combustion-derived spinel. ► XRD and HRTEM evidenced higher copper dispersion in combustion-prepared catalyst. ► The combustion-derived catalyst demonstrated superior performance in LT-WGSR.The effect of preparation method on structural properties and activity of Cu-Mn spinel oxide catalysts for the low-temperature water-gas shift reaction (LT-WGSR) has been studied. Single-step urea-combustion and coprecipitation procedures were used for synthesis of the catalysts. Catalyst characterization was performed by N2 physisorption, XRD, HRTEM, CO-TPR, CO-TPD and FTIR spectroscopy. The WGS activity was evaluated in a conventional flow reactor in the temperature range of 140–240 °C. The influence of reaction gas mixture, including either idealized or realistic reformate, H2O/CO ratio and contact time on activity were investigated. The catalytic activity tests carried out with both idealized and realistic reformate demonstrated the superior performance of the catalyst prepared by the single-step urea-combustion method. Moreover, comparison of the WGS activity of these catalysts with the one of a commercial CuO-ZnO-Al2O3 catalyst points out the potential application of Cu-Mn spinel oxide catalysts in LT-WGSR. The results revealed that the urea-combustion synthesis method is more appropriate than coprecipitation for the preparation of active and stable Cu-Mn spinel oxide catalysts for LT-WGSR.
Keywords: Cu-Mn spinel oxide; Preparation; Urea combustion; WGSR; HRTEM;

Mesoporous mixed oxide catalysts via non-hydrolytic sol–gel: A review by Damien P. Debecker; Vasile Hulea; P. Hubert Mutin (192-206).
Display Omitted► The preparation of mixed oxides with good homogeneity and texture is a challenge. ► Opportunities offered by non-hydrolytic sol–gel routes are reviewed. ► Ti―Si(―Me3Si)(―MeSi), Fe―Al, Co(―Si)―Al, Nb―V(―Si), V(―W)(―Mo)―Ti, Ag(―Nb)―Al, Mo―Si―Al, Zr―Si, catalysts. ► Comparison with conventional catalysts. ► Oxidation, epoxidation, VOC abatement, DeNO x , metathesis, alkylation, etc.Despite the enormous amount of research dedicated to this topic in the last 20 years or so, there is still a need for a general, cost-effective methodology allowing the synthesis of mesoporous mixed oxide catalysts.This review deals with the synthesis and catalytic applications of mixed oxides prepared by the non-hydrolytic sol–gel (NHSG) process based on the reaction of chloride precursors with ether or alkoxide oxygen donors. This NHSG process offers simple, one-step syntheses of mixed oxides with well-controlled compositions and non-ordered mesoporous textures, avoiding the use of supercritical drying or templates. Over the last decade, this process has been used to prepare various mesoporous mixed oxide catalysts, which showed real potential in major reactions such as partial and total oxidation, reduction of NO x , alkene metathesis, or alkylation.The main reactions involved in this NHSG process and the characteristics of the resulting mixed oxides are described in the first part of this review, underlining the decisive advantages in terms of simplicity and of control (in terms of composition, homogeneity or texture) offered by this process. In a second part, the literature dealing with mixed oxide catalysts prepared by this NHSG method is exhaustively reviewed and the catalytic performance of NHSG catalysts is compared, whenever possible, to that of catalysts with similar compositions prepared by other methods.The excellent catalytic performances of NHSG-catalysts (notably Si―Ti, Ti―V and Si―Al―Mo catalysts) compared to state-of-the art aerogels or ordered mesoporous materials evidences the potential of this sol–gel method, which should open the door to the synthesis of improved catalysts and to the discovery of new catalysts.
Keywords: Nonhydrolytic sol gel; Non aqueous; Oxidation; Metathesis; NO x reduction; Mesopores;

Display Omitted► High surface area alumina supported vanadia prepared by flame spray pyrolysis. ► Supported vanadia monomers or oligomers were the products, not crystalline vanadia. ► Best selectivity to propene obtained for vanadia monomers. ► In situ X-ray absorption spectroscopy measurements for in operando structural analysis. ► Partial reduction of vanadia oligomers whereas vanadia monomers remain oxidized.A series of five vanadia on alumina catalysts for oxidative dehydrogenation of propane to propene were synthesized by flame spray pyrolysis (FSP) using vanadium(III)acetylacetonate and aluminium(III)acetylacetonate dissolved in toluene as precursors. The vanadium loading was 2, 3, 5, 7.5 and 10 wt.%. The catalysts were subsequently characterized by BET surface area, X-ray diffraction (XRD), Raman, UV–vis diffuse reflectance and X-ray absorption spectroscopy (XAS) as well as measurement of the catalytic performance. The catalysts had specific surface areas from 143 to 169 m2/g corresponding to average particles diameters from 9.0 to 10.9 nm and apparent vanadia surface densities from 1.4 to 8.4 VO x /nm2. The only crystalline phase detected by XRD was γ-Al2O3, except at 10 wt.% vanadium where traces of crystalline vanadia were observed. Raman spectroscopy showed vanadia monomers at 2 and 3 wt.% V (1.4 and 2.1 VO x /nm2), a mixture of vanadia oligomers and monomers at 5 wt.% V (3.6 VO x /nm2) and mainly oligomers at 7.5 and 10 wt.% V (6.0 and 8.4 VO x /nm2). Diffuse reflectance UV–vis and extended X-ray absorption fine structure (EXAFS) spectroscopy measurements supported the results of Raman spectroscopy. In situ X-ray absorption near edge structure (XANES) spectroscopy showed that the vanadia can be reduced when operating at low oxygen concentrations. The catalyst performance was determined in fixed bed reactors with an inlet gas composition of C3H8/O2/N2  = 5/25/70. The main products were propene, CO and CO2, with traces of ethene and acrolein. Comparing propene selectivity as function of propane conversion the most selective catalysts were the 2 and 3 wt.% V samples, which contained mostly vanadia monomers according to Raman spectroscopy. The best propene yield of 12% was obtained with the 2 wt.% vanadium catalyst while the best space time yield of 0.78 gpropene/(gcat·h) at 488 °C was obtained with the 3 wt.% V catalyst.
Keywords: Flame spray pyrolysis; Vanadia; Oxidative dehydrogenation; Propane; Propene; Nanoparticle;

Energy consumption of the electrolytic hydrogen production using Zn–Co–Mo based activators—Part I by Sladjana Lj. Maslovara; Snezana M. Miulovic; Milica P. Marceta Kaninski; Gvozden S. Tasic; Vladimir M. Nikolic (216-219).
Display Omitted► Investigation on the energy consumption at Zn–Co–Mo catalyst for the HER. ► Zn–Co–Mo catalyst electrodeposited in situ under working conditions of the industrial electrolyser. ► Zn–Co–Mo catalyst reveals lowering of the energy consumption compared to industrial nickel electrodes.Alkaline water electrolysis is one of the easiest methods for hydrogen production. Simplicity and usefulness are the two main features that characterize this method. The challenges for widespread use of water electrolysis are to reduce energy consumption, cost, durability and safety.In our investigation we obtain the results about energy efficiency system with the addition of ionic activators (i.a.) – Co(en)3Cl3, Na2MoO4 and ZnCl2, in 6 M KOH solution. The requirements per mass unit of hydrogen produced are reduced up to 15% just using simplified process of the in situ activation with d-metals. The most important result of this study is that obtained deposit exhibit long-term stability at elevated temperatures and high current densities, like industrial conditions.
Keywords: Alkaline electrolysis; Hydrogen production; Ionic activators; Energy consumption;

Electrocatalytic activity of ZnCoMo based ionic activators for alkaline hydrogen evolution—Part II by Snezana M. Miulovic; Sladjana Lj. Maslovara; Ivana M. Perovic; Vladimir M. Nikolic; Milica P. Marceta Kaninski (220-226).
Display Omitted► In situ activation is proposed using ionic activators based on of Zn, Co and Mo. ► Polarization curves revel no change reaction mechanism of the HER. ► The roughness factor values for the ZnCoMo based i.a. are very high. ► SEM images show that the obtained deposits are mostly based on cobalt.Nickel electrodes are widely used in industrial water electrolysis cells for electrochemical production of hydrogen. To avoid extensive deactivation problems and enhance the efficiency of the electrolyser cathode, in this work in situ activation is proposed using ionic activator (i.a.) based on combination of three d-metals: Zn, Co and Mo. Polarization curves, obtained at different temperatures (303–343 K), reveal that the addition of ZnCoMo based i.a. did not change reaction mechanism when compared to the HER mechanism on nickel cathode in standard electrolyte. The electrochemical impedance spectroscopy measurements were employed to further investigate the origin of obtained electrocatalytic effect on the HER. The morphology of obtained coatings was examined by scanning electron microscopy.
Keywords: Electrolysis; Hydrogen evolution reaction; Ionic activators; EIS; Tafel analysis;

Display Omitted► Dry ball milling method can be applied as a dry synthesis method of SCR catalyst. ► The structure of V species transformed from the crystallite V2O5 to monomeric. ► (V4+  + V3+)/V5+ ratio and NO x conversion have a proportional relationship.A catalyst prepared by a mechanochemical method enables changes in physico-chemical properties such as surface area, particle size and phase. Accordingly, after preparing the catalyst by synthesizing V2O5 and anatase TiO2 with the mechanochemical method, a study on the selective catalytic reduction (SCR) reactive properties of NH3 was performed. The dry ball milling method was shown to be compatible with the dry synthesis method of the SCR catalyst by combining V2O5 and TiO2. The properties of the catalyst were studied using physio-chemical analyses, including BET surface area, X-ray diffraction (XRD), Raman spectroscopy, H2 temperature programmed reduction (H2-TPR), diffuse reflectance UV–VIS spectroscopy and X-ray photoelectron spectroscopy (XPS). The V2O5 crystallite peak decreased with increased milling time, and the monomeric species was formed. The maximum reducing temperature (T max) decreased by H2-TPR. Improvements in the redox capacity were identified by experiments in which O2 was introduced and subsequently removed as well as by reoxidation analysis. Additionally, the presence of non-stoichiometric vanadium and an increased number of surface atoms were identified through the milling effect. A correlation was identified between the ratio of (V4+  + V3+)/V5+ and the catalyst NO x conversion rate.
Keywords: NO x removal; NH3 SCR; Dry ball milling; Mechanochemical;

Vapor-phase hydrogenation of ethyl lactate over copper–silica nanocomposites by Palraj Kasinathan; Ji-Woong Yoon; Dong Won Hwang; U-Hwang Lee; Jin-Soo Hwang; Young Kyu Hwang; Jong-San Chang (236-242).
Display Omitted► The dispersion of Cu on silica was enhanced greatly by the precipitation–deposition method. ► Cu loading could be increased up to 80 wt% on silica with maintaining Cu particle size smaller than 20 nm. ► The productivity of 1,2-propanediol is enhanced significantly with Cu–silica nanocomposites.Silica-supported Cu was studied as a catalyst for hydrogenation of ethyl lactate to produce 1,2-propanediol. The dispersion of Cu on silica was highly influenced by the preparation method, which was a major factor affecting the catalytic activity in the reaction. The conversion of ethyl lactate over the catalyst by precipitation–deposition method was about two times higher than that by sol–gel and wet impregnation methods, although the BET surface area of the catalyst by precipitation–deposition was much lower. Copper loading could be increased up to 80 wt% on silica while maintaining a Cu particle size smaller than 15 nm by the precipitation–deposition method, where the highest specific Cu surface area was obtained. In this nanocomposite, further growth of Cu crystals seemed to be prevented by the inclusion of silica nanoparticles between Cu nanoparticles. Compared with hydrogenation of lactic acid over the conventional lowly loaded silica-supported Cu catalysts, the productivity of 1,2-propanediol from ethyl lactate is enhanced about 10 times under mild reaction conditions.
Keywords: Lactic acid; Ethyl lactate; 1,2-Propanediol; Hydrogenation; Copper–silica; Nanocomposite;

A viable synthesis of ferrocene tethered NHC–Pd complex via supported ionic liquid phase catalyst and its Suzuki coupling activity by Vipul Gaikwad; Rajanikant Kurane; Jagannath Jadhav; Rajashri Salunkhe; Gajanan Rashinkar (243-250).
Display Omitted► A novel ferrocene tethered N-heterocyclic carbene-Pd complex is prepared. ► The synthesized complex shows excellent catalytic activity in Suzuki coupling reaction. ► High yields with easy recovery and efficient reusability of catalyst are observed.An efficient and robust method has been devised for the synthesis of heterogeneous ferrocene tethered NHC–Pd complex using a supported ionic liquid phase (SILP) catalyst as a precursor. The versatility of the synthesized complex has been investigated by employing it in the Suzuki coupling of aryl boronic acids with aryl halides.
Keywords: Supported ionic liquid phase (SILP) catalyst; N-heterocyclic carbene (NHC); Ferrocene; Heterogeneous; Suzuki coupling; Reusability;

Effect of catalyst synthesis parameters on the metal particle size by Päivi Mäki-Arvela; Dmitry Yu. Murzin (251-281).
Display Omitted► Review on the effect of catalyst synthesis parameters on the metal particle size. ► Emphasis on the pH effect and point zero charge in the catalyst preparation. ► Several synthesis methods discussed. ► Post-synthesis methods shortly reported. ► Thermodynamic and kinetic modeling of nanoparticle formation is presented.The effect of synthesis parameters on the metal particle size in final catalysts is reviewed. Several synthesis methods, such as impregnation, deposition precipitation, strong electrostatic adsorption together with stabilization of colloidal and supported metal particles are reported with the main emphasis on the effect of pH in the preparation. In addition to synthesis parameters, also properties of the support, for example point zero charge and specific surface area are of crucial importance. The results revealed that pH and support selection are very important in tuning the metal particle size, moreover aging of the slurry also changes the metal particle size. In addition to preparation the post-synthesis methods, such as washing, calcinations and reduction are shortly reported here. Thermodynamic and kinetic modeling of nanoparticle formation is also summarized here.
Keywords: Deposition precipitation; Colloidal stabilization; Impregnation; Adsorption; Metal particle size; pH; Temperature;

Influence of calcination temperature on the structure and catalytic performance of CuO x -CoO y -CeO2 ternary mixed oxide for CO oxidation by Zhi-Gang Liu; Song-Hai Chai; Andrew Binder; Yuan-Yuan Li; Lin-Tao Ji; Sheng Dai (282-288).
Display Omitted► Mutual interaction between Co3O4 and CeO2 is involved during calcination of the catalyst. ► Oxygen vacancies are beneficial to achieve interaction between Co3O4 and CeO2. ► Enrichment of Cu and Co on the surface of as-prepared catalysts is found. ► Complete CO conversion over CCC600 is obtained at 70 °C and about 10% of CO conversion is reached at 30 °C.Influence of calcination temperature (400−800 °C) on the structure and catalytic activity of CuO x -CoO y -CeO2 ternary mixed oxide (atomic Cu:Co:Ce ratio of 1:5:5) prepared by co-precipitation method is investigated by N2 physisorption, XRD, TPR, TEM, TG-DTA, XPS, and CO oxidation reaction. The as-synthesized CuO x -CoO y -CeO2 undergoes successive structural changes with the calcination temperature, involving the hydroxide dehydration below 400 °C, enhanced interaction between Co3O4 and CeO2 at ca. 600 °C, and Co3O4 decomposition to CoO at 700 °C. The catalyst calcined at 600 °C shows a relative enrichment of Cu+ on the surface of CuO x -CoO y -CeO2 and an enhanced interaction between Co3O4 and CeO2 along with the appearance of oxygen vacancies in CeO2, which seems to be responsible for its highest catalytic activity for CO oxidation among all the tested catalysts. The complete conversion of CO is obtained at 70 °C and about 50% of CO conversion is reached at 55 °C.
Keywords: Calcination temperature; CuO-Co3O4-CeO2; Mechanism; Mutual interaction, CO oxidation;