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Applied Catalysis A, General (v.419-420, #)

Contents (pp. iii-x).

Editorial Board (pp. co2).

Catalytic hydrotreatment using NiMo/MAS catalysts synthesized from ZSM-5 nano-clusters by S. Mohanty; K. Chandra Mouli; K.Soni; J. Adjaye; A.K. Dalai (pp. 1-12).

Display Omitted► Effect of hydrothermal treatment duration on mesoporous materials synthesized from ZSM-5 nano-clusters. ► Bronsted acid sites in the materials increased with hydrothermal treatment duration. ► Optimum dispersion of Molybdenum was found on the support synthesized with 16h of hydrothermal treatment. ► Hydrotreating activity of the optimum catalyst was found to be higher than the conventional NiMo/γ-Al₂O₃ catalyst. ► EXAFS results indicate that sulfidation of Mo was highest on catalyst with 16h of hydrothermal treatment.Mesostructured alumino-silcate (MAS) materials were synthesized from ZSM-5 nano-clusters and used as catalysts supports for the hydrotreatment of a model compound and real feed stock. Supports and catalysts were thoroughly characterized by using XRD, N₂ adsorption analysis, FT-IR,²⁷Al MAS NMR, Raman, EXAFS and HRTEM techniques. The alumino-silicate materials exhibited different acid strength and textural properties depending on the duration of hydrothermal treatment of the zeolite seeds. Materials synthesized with low seeding time of 4h showed properties similar to Al-SBA-15 prepared using the direct synthesis route, whereas material with high seeding time ( t_seed=24h) resembled ZSM-5. The EXAFS study of the sulfided catalysts revealed that sulfidation was highest in the NiMo catalyst supported on mesoporous alumino-silicate synthesized from ZSM-5 seeds with 16h of hydrothermal treatment (MAS-16). Hydrotreating experiments were conducted using model compound (DBT) at 325°C and 600psi as well as real feed stock (Coker light gas oil) at industrial conditions. Catalytic activity in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) was found to be maximum for this particular catalyst (MAS-16). The same catalyst also gave higher hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) conversion than NiMo/γ Al₂O₃ in the hydrotreating of Light Gas Oil.

Keywords: Hydrothermal treatment; ZSM-5 nano-seeds; Acidity; EXAFS; Dibenzothiophene; Hydrotreatment

Preparation of carbon-supported Pt catalysts covered with microporous silica layers using organosilanes: Sintering resistance and superior catalytic performance for cyclohexane dehydrogenation by Keizo Nakagawa; Tetsuya Okayama; Yusuke Tanimoto; Ken-Ichiro Sotowa; Shigeru Sugiyama; Toshihiro Moriga; Sakae Takenaka; Masahiro Kishida (pp. 13-21).

Display Omitted► Pt particles are covered with microporous silica layers using different organosilanes. ► Sintering resistance of Pt particles at high-temperature thermal treatment. ► Pt catalysts are used for cyclohexane dehydrogenation. ► Higher conversion of cyclohexane compared with Pt catalysts without silica coating.Carbon black-supported Pt metal particles (Pt/CB) were covered with microporous silica layers using different organosilanes like methyltriethoxysilane (MTES) (SiO₂(MTES)/Pt/CB) and phenyltriethoxysilane (PhTES) (SiO₂(PhTES)/Pt/CB). Pt metal particles in Pt/CB covered with microporous silica layers were stable at high temperature up to 973K in a hydrogen atmosphere, because the microporous silica layers that wrapped around the Pt metal particles essentially prevent particle sintering. Methyl or phenyl groups were introduced into the silica layers that covered the Pt metal particles using MTES or PhTES hydrolysis. Micropores were formed in the silica layers effectively after thermal treatment at 973K. The microporous silica-coated Pt catalysts were used as model catalysts for the dehydrogenation of cyclohexane. The microporous silica-coated Pt catalysts with thermal treatment at 973K exhibited a higher conversion of cyclohexane compared with Pt/CB. Especially, the SiO₂(PhTES)/Pt/CB catalysts showed relatively higher conversion of cyclohexane compared with the other silica-coated Pt catalysts even when the SiO₂ loading was high. Microporous silica layers with a larger micropore volume promoted the diffusion of cyclohexane during the catalytic reaction.

Keywords: Carbon-supported Pt catalyst; Silica coating; Microporous silica layer; Sintering resistance; Cyclohexane dehydrogenation

Tin exchanged zeolite as catalyst for direct synthesis of α-amino nitriles under solvent-free conditions by Arpan K. Shah; Noor-ul H. Khan; Govind Sethia; S. Saravanan; Rukhsana I. Kureshy; Sayed H.R. Abdi; Hari C. Bajaj (pp. 22-30).

Display Omitted► The catalyst Sn-exchanged HBeta zeolite was synthesized by ion-exchange method. ► The catalyst was effectively used in the Strecker reaction of aldehydes and ketones. ► The product α-Amino nitriles were achieved in high yield (∼96%) in 10–120min. ► The present protocol uses safer cyanating agent under solvent free condition. ► The catalyst Sn-exchanged zeolite is recycled several times successfully.Sn exchanged HBeta zeolite was prepared and characterized by PXRD, surface area, TPD and TEM analysis. The Sn exchanged zeolite was found to be highly efficient catalyst for the direct synthesis of α-amino nitrile from various ketones and aldehydes with amine and trimethyl silylcyanide (TMSCN) under solvent-free condition. Excellent yield of α-amino nitrile (up to 96%) was achieved within 10–120min at room temperature. The Sn exchanged HBeta zeolite was recovered and reused several times without the loss of its catalytic performance.

Keywords: Strecker reaction; α-Amino nitriles; Heterogeneous catalysis; Zeolite

Co–Ru/SiC impregnated with ethanol as an effective catalyst for the Fischer–Tropsch synthesis by Benoit de Tymowski; Yuefeng Liu; Christian Meny; Christophe Lefèvre; Dominique Begin; Patrick Nguyen; Charlotte Pham; David Edouard; Francis Luck; Cuong Pham-Huu (pp. 31-40).

Display Omitted► Influence of ethanol as an impregnation solvent for cobalt catalyst. ► Ethanol-based catalyst exhibits high activity under severe reaction conditions. ► Characterization of the Co phases by⁵⁹Co NMR. ► Higher activity is attributed to the presence of small hcp Co particles.Silicon carbide containing cobalt (30wt.%) doped with 0.1wt.% of ruthenium catalysts prepared by incipient wetness impregnation of cobalt nitrate with either ethanol or water were tested in the Fischer–Tropsch synthesis (FTS) in a fixed-bed configuration. The catalyst prepared with ethanol exhibits a higher FTS performance compared to the one prepared with water and especially at high reaction temperature, i.e. 230°C. The FTS performance of the cobalt-based catalyst impregnated with ethanol further increases, under high temperature and high space velocity, to reach a steady state reaction rate of0.54 gCH2gcatalyst−1 h−1, and a relatively high C₅₊ selectivity of about 90%. In addition, the catalyst also exhibits a relatively high stability as a function of time on stream.⁵⁹Co zero field NMR analysis has indicates that the proportion of cobalt atoms engaged in the small hcp cobalt particles (<8nm) was higher for the ethanol impregnated catalyst and also to the more homogeneous dispersion of the ruthenium atoms within the cobalt network forming an alloy.

Keywords: Silicon carbide; Cobalt; Ruthenium; Fischer–Tropsch synthesis; Ethanol; ⁵⁹; Co NMR; Stacking faults

Dehydration of 1,5-pentanediol over rare earth oxides by Fumiya Sato; Hiro Okazaki; Satoshi Sato (pp. 41-48).

Display Omitted► The dehydration of 1,5-pentanediol to 4-penten-1-ol over rare earth oxides was studied. ► Sc₂O₃, Yb₂O₃, and Lu₂O₃ showed the selectivity to 4-penten-1-ol with higher than 74mol%. ► Reactivity of alkanediols over Yb₂O₃ varies with the carbon number of diols. ► The reactivity order: 1,4-butanediol 1,3-diols≫1,5-pentanediol≫1,6-hexanediol.Vapor-phase catalytic dehydration of 1,5-pentanediol was investigated over rare earth oxides (REOs) at 325–450°C. The conversion of 1,5-pentanediol over REOs calcined at 700 and 800°C was higher than that calcined at 500°C. Sc₂O₃, Yb₂O₃, and Lu₂O₃ with cubic bixbyite structure showed the selectivity to 4-penten-1-ol with higher than 74mol%, while REOs with hexagonal and monoclinic structures showed the selectivity with less than 50mol%. Especially, Yb₂O₃ and Lu₂O₃ calcined at 1000°C showed high formation rate of 4-penten-1-ol per specific surface area over 1mmolh⁻¹m⁻² at 400°C. In the Yb₂O₃ catalyst calcined at 800°C, the conversion of 1,5-pentanediol was increased up to 74.4mol% with increasing contact time, together with stable selectivity to 4-penten-1-ol of 71.8mol%. In comparing the reactivity of alkanediols to form the corresponding unsaturated alcohols over Yb₂O₃, we found the reactivity of alkanediols into the corresponding unsaturated alcohols was the following order: 1,4-butanediol>1,3-diols≫1,5-pentanediol≫1,6-hexanediol.

Keywords: Dehydration; 1,5-Pentanediol; 4-Penten-1-ol; Rare earth oxides; Bixbyite; Reactivity

Influence of TiO₂ crystal structure on acrylonitrile decomposition over Ag/TiO₂ by Tetsuya Nanba; Shoichi Masukawa; Junko Uchisawa; Akira Obuchi (pp. 49-52).

Display Omitted► Crystal phase of TiO₂ affects product selectivity in acrylonitrile decomposition on Ag/TiO₂. ► Ag/anatase–TiO₂ shows high N₂ selectivity, and Ag/rutile–TiO₂ shows high NO_x selectivity. ► Anatase and rutile phase tend to form ionic and metallic Ag, respectively. ► Ionic Ag catalyzes hydrolysis and metallic Ag catalyzes total oxidation.The catalytic decomposition of acrylonitrile over Ag supported on different crystal phases of TiO₂ was studied. Ag/TiO₂ containing anatase TiO₂ exhibited high NH₃ and N₂ selectivity at low and high temperatures, respectively, whereas Ag/TiO₂ composed of only rutile TiO₂ exhibited medium N₂ and high NO_x selectivity at low and high temperatures, respectively. X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction by H₂ revealed that the anatase phase favors the formation of ionic Ag, whereas the rutile phase favors that of metallic Ag. We concluded that product selectivity in acrylonitrile decomposition was influenced by the oxidation state of Ag, which was in turn affected by the crystal phase of TiO₂.

Keywords: Acrylonitrile; Decomposition; Ag; TiO; ₂; Anatase; Rutile

Ionic liquids as novel catalysts for methane conversion under a DC discharge plasma by M. Yu; L.Y. Zhai; Q. Zhou; C.P. Li; X.L. Zhang (pp. 53-57).

Display Omitted► Nine imidazolium-based ionic liquids as catalysts in gas–liquid plasma. ► Catalysts for methane converting to C₂ hydrocarbons in CH₄–H₂ plasma system. ► Ionic liquids increase the optical spectrum intensity of C₂, CH, H, C⁺, and C species. ► Ionic liquid is steady under cold plasma.Nine imidazolium-based ionic liquids were investigated as novel catalysts for methane conversion in a direct current (DC) discharge plasma reactor. The conversion of methane increased from 21.2% to 43.6% in the plasma system when the C₆MIMHSO₄ IL was used as a catalyst, C₆MIMBF₄ successfully achieved 91.0% selectivity for C₂ hydrocarbons. The results of the optical emission spectroscopy indicate that the intensity of the C₂, CH, H, C⁺, and C active species from methane decomposition increased when C₆MIMHSO₄, C₆MIMCF₃COO, and C₆MIMBF₄ were introduced into the plasma system. FTIR analysis indicates that C₆MIMBF₄ is steady in the DC discharge plasma.

Keywords: Plasma; Ionic liquids; Methane conversion; Optical emission spectroscopy

Sub-ambient CO oxidation over Au/MO_x/CeO₂-Al₂O₃ (M=Zn or Fe) by Tomás Ramírez Reina; Svetlana Ivanova; María Isabel Domínguez; Miguel Angel Centeno; José Antonio Odriozola (pp. 58-66).

Display Omitted► Transition metal oxide (ZnO and Fe₂O₃) promotion of the commercial CeO₂-Al₂O₃. ► Gold nanoparticles deposition through direct anionic exchange assisted by ammonia. ► Optimal loading of doping oxide of one theoretical monolayer is found. ► All samples present sub-ambient CO oxidation activity. ► Gold redispersion occurs when starting the CO oxidation below room temperature for the Fe₂O₃ doped samples.A series of ZnO and Fe₂O₃ modified ceria/alumina supports and their corresponding gold catalyst were prepared and studied in the CO oxidation reaction. ZnO-doped solids show a superior catalytic activity compared to the bare CeO₂-Al₂O₃, which is attributed to the intimate contact of the ZnO and CeO₂ phases, since an exchange of the lattice oxygen occurs at the interface. In a similar way, Fe₂O₃-modified supports increase the ability of the CeO₂-Al₂O₃ solids to eliminate CO caused by both the existence of Ce–Fe contact surface and the Fe₂O₃ intrinsic activity. All of the gold catalysts were very efficient in oxidising CO irrespective of the doping metal oxide or loading, with the ZnO containing systems better than the others. The majority of the systems reached total CO conversion below room temperature with the ZnO and Fe₂O₃ monolayer loaded systems the most efficient within the series.

Keywords: Gold catalyst; Zinc oxide; Iron oxide; Monolayer; CO oxidation

The effect of the N atom on the dehydrogenation of heterocycles used for hydrogen storage by Farnaz Sotoodeh; Benjamin J.M. Huber; Kevin J. Smith (pp. 67-72).

Display Omitted► H₂ recovery rates from heterocycles is reported on a Pd/C catalyst. ► H₂ recovery from dodecahydro-N-ethylcarbazole is faster than from dodecahydrocarbazole. ► H₂ recovery from dodecahydrocarbazole is faster than from dodecahydrofluorene. ► The presence of the N atom in the heterocycle increases the dehydrogenation rate.The effect of the N atom on the hydrogen release rate from heterocyclic compounds was studied by comparing the dehydrogenation rate of dodecahydro-N-ethylcarbazole, dodecahydrocarbazole and dodecahydrofluorene. Over a 5wt% Pd/C catalyst, hydrogen recovery was fastest (TOF ∼60min⁻¹ at 443K and 101kPa) from dodecahydro-N-ethylcarbazole and ∼3 times faster than that of dodecahydrocarbazole. Dodecahydrofluorene dehydrogenation was the slowest among the compounds examined, with less than 1wt% H₂ recovered after more than 20h at 443K, although selectivity to the completely dehydrogenated product was 95%. Despite catalyst poisoning by the N in dodecahydrocarbazole and its dehydrogenated product, the presence of the N in the heterocycle increased the dehydrogenation reaction rate compared to dodecahydrofluorene, demonstrating that heterocycles are better candidates for H₂ storage than polycycles.

Keywords: Dehydrogenation; Kinetics; Catalyst; Dodecahydro-; N; -ethylcarbazole; Hydrogen storage

Transesterification of rapeseed oil under flow conditions catalyzed by basic solids: MAl(La)O (M=Sr, Ba), MMgO (M=Y, La) by O.V. Sherstyuk; A.S. Ivanova; M.Y. Lebedev; M.V. Bukhtiyarova; L.G. Matvienko; A.A. Budneva; A.N. Simonov; V.A. Yakovlev (pp. 73-83).

Display Omitted► Catalysts MAl(La)O (M=Sr, Ba), MMgO (M=Y, La) synthesized by precipitation. ► Catalysts for rapeseed oil transesterification with methanol in flow fixed bed reactor. ► Their surfaces contain three types of basic sites strongly differing in strength. ► The activity of the catalysts increases in order SrAlO3 (FTIR), low temperature nitrogen adsorption and heat desorption of argon and their catalytic activity towards the transesterification reaction of rapeseed oil was studied in the flow fixed bed reactor at 200°C and 20atm. The phase composition, texture and surface composition of the catalysts are determined by their chemical nature and calcination temperature. The performance of the catalysts calcined at 700–750°C diminishes in the order of SrLaO>BaLaO>LaMgO≥YMgO>BaAlO⁷⁰⁰>SrAlO⁷⁰⁰ and is in a straight correlation with the integrated intensity of absorption of surface carbonate species representing the amount of the strong basic sites on the surface of the catalysts. Thermal treatment of MAlO (M=Sr, Ba) catalysts at 1200°C exerts minor influence on their performance.

Keywords: Biodiesel; Solid base catalysts; FTIR spectra; Rapeseed oil; Transesterification

Microspectroscopic insight into the deactivation process of individual cracking catalyst particles with basic sulfur components by Javier Ruiz-Martínez; Inge L.C. Buurmans; William V. Knowles; David van der Beek; Jaap A. Bergwerff; Eelco T.C. Vogt; Bert M. Weckhuysen (pp. 84-94).

Display Omitted► Basic sulfur poisons interact with Brønsted acid sites forming oligomeric carbocations. ► Oligomeric carbocations are coke intermediates. ► Coking depends on zeolite structure and nature of thiophenes. ► Confocal fluorescence microscopy reveals the location of sulfur poisons within FCC particles.The effect and localization of thiophene-like poisons were studied on fluid catalytic cracking (FCC) catalyst at the individual particle level. The thiophene-like poisons interact on the Brønsted acid sites of the catalytic materials, forming oligomeric carbocations and coke species, which absorb and emit light in the visible region. The matrix components are not active in the formation of those light absorbing species. In contrast, zeolite Y and ZSM-5 were very active in inducing oligomer formation and the product distribution was different depending on the zeolite pore structure. Comparison of thiophene results with alkane and alkene catalytic cracking studies reveal that FCC particles have more affinity to react with thiophene molecules compared to n-hexane, but 1-hexene may compete with thiophene in the formation of carbocationic species on Brønsted acid sites. Moreover, a different reactivity was observed in thiophenes with distinct electron withdrawing/releasing substituents and molecular sizes. Our results demonstrate that the carbocations are coke intermediates, and the FCC particles containing zeolite Y promote to a higher extent coke formation: the large supercages allow the accommodation of more bulky coke species. On the other hand, FCC particles containing ZSM-5 stabilize the carbocations within the narrower cylindrical pores, diminishing coke formation. Confocal fluorescence microscopy can resolve the location of sulfur components at the single particle level with submicron resolution. Fluorescence microscopy images reveal heterogeneous domains with highly bright fluorescence across the FCC particles, which are attributed to the selective formation of oligomeric carbocations and coke species on the zeolitic material. The presence of thiophenes with different substituents and sizes was also studied by this approach. This demonstrates the potential of confocal fluorescence microscopy to identify reactivity differences of thiophene-like molecules on FCC catalyst particles in a spatially-resolved manner.

Keywords: Confocal fluorescence microscopy; UV–vis microspectroscopy; Poisoning; Thiophene; Coke formation; Fluid catalytic cracking catalysts

Influence of the activation atmosphere on the hydrodesulfurization of Co-Mo/SBA-15 catalysts prepared from sulfur-containing precursors by G. Alonso-Núñez; J. Bocarando; R. Huirache-Acuña; L. Álvarez-Contreras; Z.-D. Huang; W. Bensch; G. Berhault; J. Cruz; T.A. Zepeda; S. Fuentes (pp. 95-101).

Display Omitted► Mesoporous SBA-15 material support of binary Co-Mo hydrodesulfurization catalysts. ► The effects of atmosphere and activation temperature for active CoMo/SBA-15 catalysts. ► Confinement effect of MoS₂ slabs inside the SBA-15 channels.Mesoporous SBA-15 material was used as support of binary Co-Mo hydrodesulfurization (HDS) catalysts prepared using a novel approach based on the use of already sulfided precursors (ammonium tetrathiomolybdate and cobalt diethyldithiocarbamate). The effects of atmosphere and activation temperature were studied to optimize the preparation of highly active CoMo/SBA-15 hydrodesulfurization catalysts. Two sets of catalysts were synthesized using either a N₂/H₂ (10% H₂) or a H₂/H₂S (15% H₂S) atmosphere at three different temperatures of activation (723, 773 and 823K). The catalysts were tested in the HDS of dibenzothiophene (DBT) and the catalysts were characterized by N₂ physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The use of already sulfided precursors leads to a homogeneous dispersion of the active phase inside the SBA-15 channels. Moreover, the N₂/H₂ activation procedure at 723K allows obtaining optimized HDS active catalysts. Finally, a confinement effect of MoS₂ slabs inside the SBA-15 channels leads to a high selectivity along the direct desulfurization pathway.

Keywords: Hydrodesulfurization; SBA-15; Activation; ATM; Dithiocarbamate; Confinement effect

Catalytic fast pyrolysis of furfural over H-ZSM-5 and Zn/H-ZSM-5 catalysts by Wei-Liang Fanchiang; Yu-Chuan Lin (pp. 102-110).

Display Omitted► Furfural can be converted into aromatics through catalytic fast pyrolysis. ► Reaction temperature, contact time, and catalytic promoter are keys to manipulate product distribution. ► The introduction of Zn species in H-ZSM-5 can substantially enhance aromatics yields.Furfural, a cellulose model compound, was converted into gasoline-range fuels through catalytic fast pyrolysis. H-ZSM-5-based catalysts were employed in a continuous fixed bed system. The reaction temperature, reactant contact time, and catalytic promoter are keys to manipulate the product distribution. The first step in furfural conversion is the decarbonylation of furfural to form furan, followed by furan conversion to intermediates (e.g., cyclohexene and 3,4-dimethylbenzaldehyde) in the ZSM-5 pores. These intermediates can then be transformed into aromatics, coke, light olefins, and carbon oxides. A reaction temperature of 500°C generated the highest yield of aromatics and the lowest amount of coke. A long contact time (∼1.5s) also provided the highest aromatic selectivity. The promoter, zinc oxide, plays an important role in hydrogen atom transfer. This is attributed to the change of acid site concentration and Lewis acid sites created by anchored Zn ions.

Keywords: Fast pyrolysis; Furfural; Zeolite; Biofuels; ZSM-5

The influence of citric acid on the synthesis and activity of high surface area MoP for the hydrodeoxygenation of 4-methylphenol by Victoria M.L. Whiffen; Kevin J. Smith; Suzana K. Straus (pp. 111-125).

Display Omitted► High surface area MoP was prepared by mixing citric acid with metal salt solutions. ► Mo(C₄H₅O₃CN)O₂·HPO₄ was produced following calcination. ► Reduction of Mo(C₄H₅O₃CN)O₂·HPO₄ yielded MoP nanoparticles and residual C. ► C acted as a structural promoter to limit agglomeration of the MoP crystallites. ► The hydrodeoxygenation of 4-methylphenol is shown be structure insensitive over MoP.Unsupported, high surface area MoP was synthesized by adding citric acid (CA) to solutions of ammonium heptamolybdate and diammonium hydrogen phosphate followed by drying (397K), calcination (773–973K), and reduction in H₂ (923K). A tetrameric Mo citrate precursor was formed after drying which decomposed into a monomer of the form, Mo(C₄H₅O₃CN)O₂·HPO₄ following calcination. Reduction of this monomer produced CH₄, CO, CO₂, NH₃, H₂O, and MoP. The C content of the reduced MoP-CA catalysts decreased from 12.8 to 4.0wt% as the calcination temperature increased from 773 to 973K, whereas the surface area decreased from 136m²/g to 53m²/g and the MoP particle size increased from 5 to 9nm, respectively. The residual C acted as a structural promoter of the calcined samples, limiting agglomeration of the MoP crystallites during reduction so that nanoparticles (5–9nm) of MoP were produced. The HDO of 4-methylphenol over the MoP-CA catalysts was found to be structure insensitive with an initial turnover frequency (TOF) of 0.079s⁻¹ at 623K and 4.4MPa H₂. The ratio of hydrogenation to direct deoxygenation of 4-methylphenol (TOF_HYD:TOF_DDO=0.78:1) was independent of the MoP particle size and greater than that observed over MoS₂.

Keywords: Hydrodeoxygenation; Hydrogenation; 4-Methylphenol; Structure sensitivity; Molybdenum phosphide; Catalyst preparation; Citric acid; Molybdenum citrate; Unsupported catalyst

Controlling hydrogenation of CO and CC bonds in cinnamaldehyde using silica supported Co-Pt and Cu-Pt bimetallic catalysts by Renyang Zheng; Marc D. Porosoff; Jacob L. Weiner; Shuliang Lu; Yuexiang Zhu; Jingguang G. Chen (pp. 126-132).

.Display Omitted► SiO₂ supported bimetallic catalysts are used for cinnamaldehyde hydrogenation. ► Bimetallic catalysts are more active than monometallic catalysts. ► Co-Pt enhances CO bond hydrogenation while Cu-Pt prefers CC bond hydrogenation. ► Activity/selectivity trend is consistent with previous surface science studies.Liquid phase hydrogenation of cinnamaldehyde was evaluated over SiO₂ supported Co-Pt and Cu-Pt bimetallic and Co, Cu, Pt monometallic catalysts in a batch reactor. H₂-temperature-programmed reduction (H₂-TPR) was utilized to characterize the reduction behavior and pulse CO chemisorption measurement was performed to characterize the number of active sites of the catalysts. Transmission electron microscopy (TEM) analysis was used to characterize metallic particle size distribution and extended X-ray absorption structure (EXAFS) measurements were performed to verify the bimetallic bond formation. The reactor evaluation results show that Co-Pt and Cu-Pt bimetallic catalysts exhibit much higher hydrogenation activity than the corresponding monometallic catalysts, and Co-Pt shows much higher selectivity toward CO bond hydrogenation than Cu-Pt. The trend of hydrogenation activity and selectivity is consistent with previous studies of the hydrogenation of unsaturated aldehydes on model bimetallic surfaces.

Keywords: Hydrogenation; Cinnamaldehyde; Bimetallic Catalysts; Co-Pt; Cu-Pt

Enhanced activity of Ru/TiO₂ catalyst using bisupport, bentonite-TiO₂ for hydrogenolysis of glycerol in aqueous media by Noraini Hamzah; Norasikin Mohamad Nordin; Ainol Hayah Ahmad Nadzri; Yah Awg Nik; Mohamad B. Kassim; Mohd Ambar Yarmo (pp. 133-141).

.Display Omitted► Bentonite-TiO₂ supported Ru is an efficient catalysts for glycerol hydrogenolysis. ► The activity of the catalyst depends on the ratios of bentonite-TiO₂. ► The Ru particles is well dispersed on bentonite-TiO₂ support. ► This catalyst showed good activity even at mild reaction conditions. ► The catalyst is reusable and remain active even after for four times regenerate.A combination of bentonite-TiO₂ was used as support to enhance the activity of Ru/TiO₂ catalyst in hydrogenolysis of aqueous glycerol to 1,2-propanediol. A series of bentonite, TiO₂, SiO₂ and Al₂O₃ supported Ru catalyst were fabricated and characterized by XRD, XPS, BET, FESEM-EDX and TEM to establish some physicochemical properties of the catalysts. The activity of the catalysts was tested in glycerol hydrogenolysis reaction and were found to be in the following increasing order: Ru/SiO₂2≈Ru/Al₂O₃2 with a reaction duration of 7h. The Ru/TiO₂ catalyst exhibited the highest selectivity (83.7%) for hydrogenolysis of glycerol to 1,2-propanediol and with 38.8% conversion only. The activity of Ru/TiO₂ catalyst was enhanced by adding bentonite to the titania support at 1:2 ratio resulting in an 80% increasing the activity from 38.8% to 69.8% under the same optimum condition for Ru/TiO₂ while maintaining an 80% selectivity to 1,2-propanediol. TPD-NH₃ analysis found that mixed support could increase catalyst acidity. CO pulse chemisorption analysis revealed that Ru particles was well dispersed with the smallest average size particles (1.5nm) which could contribute to high activity of Ru/TiO₂ catalyst for hydrogenolysis of glycerol.

Keywords: Hydrogenolysis; Glycerol; Bentonite-TiO; ₂; Ruthenium catalyst; 1,2-Propanediol

Kinetic analysis of reduction process of supported Rh/Al₂O₃ catalysts by time resolved in-situ UV–vis spectroscopy by Qiang Lin; Ken-ichi Shimizu; Atsushi Satsuma (pp. 142-147).

Display Omitted► Kinetic analysis of the reduction of Rh³⁺ to Rh⁰ on Rh/Al₂O₃. ► In-situ UV–vis can monitor the dynamics of Rh/Al₂O₃ with very low Rh-loading. ► Reduction rate decreases with the increase in calcination temperature. ► Activation energy of the reduction is independent of the calcination temperature and the Rh-loading.Kinetic analysis of reduction of Rh/Al₂O₃ with low Rh-loadings (0.01–0.1wt%) has been carried out by time resolved in-situ UV–vis spectroscopy. Based on XAFS and UV–vis spectra, it was indicated that Rh was present as surface isolated Rh³⁺ on catalyst calcined at 773K in air. The rate of reduction of Rh³⁺ to metallic Rh⁰ was determined by in-situ UV–vis measurements under a flow of 1%H₂/He at 523–823K. The reduction rate increased with Rh-loading but decreased as the calcination temperature elevated. The decrease of metallic Rh⁰ formation with the calcination temperature was in harmony with the reaction rate of CO oxidation. The apparent activation energy ( E_a) for the reduction of Rh³⁺ to Rh⁰ was found to be constant around 60–62kJmol⁻¹ and independent of the calcination temperature and the Rh-loading, indicating the equivalent intrinsic activity of supported Rh species on Rh/Al₂O₃ with the low Rh-loadings.

Keywords: Rhodium; Deactivation; Reduction; In-situ UV–vis; Kinetic analysis

Effects of titanium impurity on alumina surface for the activity of Co/Ti–Al₂O₃ Fischer–Tropsch catalyst by Seon-Ju Park; Seung-Moon Kim; Min Hee Woo; Jong Wook Bae; Ki-Won Jun; Kyoung-Su Ha (pp. 148-155).

Display Omitted► Effect of Ti impurity on Al₂O₃ was investigated on cobalt-based FT synthesis. ► Titanium content of 0.5wt% on Al₂O₃ was found to be optimal. ► Enhanced activity was suggested by the suppressed aggregation of cobalt clusters. ► The positive effect is related with the modified Al₂O₃ surface acidity by Ti.The surface impurity of titanium with a low concentration on alumina was investigated to elucidate the effects of titanium to catalytic performance on Co/Ti–Al₂O₃ catalysts during Fischer–Tropsch (FT) synthesis. Titanium impurity is possibly incorporated as an impurity in Al₂O₃ preparation process, and its content could alter the surface characters of Al₂O₃. The variation of surface characteristics also significantly alters the dispersion of Co₃O₄ clusters, reducibility and it consequently changes the catalytic activity. In the present study, titanium impurity with a composition of 0.2–0.5wt% on γ-Al₂O₃ was found to be optimal to obtain a high catalytic performance with respect to CO conversion and C₅+ selectivity. The enhanced catalytic activity on Ti-modified Co/Al₂O₃ catalyst was mainly attributed to the increased dispersion of cobalt clusters homogeneously with a suppression of cluster aggregation during FT reaction, and it is mainly resulted from the surface modification of alumina with a low content of titanium oxides by changing the surface acidity of γ-Al₂O₃.

Keywords: Fischer–Tropsch synthesis; Titanium; Cobalt cluster size; Reducibility; Acidity modification; γ-Al; ₂; O; ₃

Pt–Re–Ge/Al₂O₃ catalysts for n-octane reforming: Influence of the order of addition of the metal precursors by Luciene S. Carvalho; Karla C.S. Conceição; Vanina A. Mazzieri; Patricio Reyes; Carlos L. Pieck; Maria do Carmo Rangel (pp. 156-163).

Display Omitted► The order of adding the metal precursors affects the properties of Pt–Re–Ge catalysts. ► By adding Pt before Re and Ge catalysts with low hydrogenolysis activity are obtained. ► By adding Ge before Pt and Re high active catalysts to hydrogenolysis are obtained. ► RePtGe catalyst can be used to produce isoparaffins-rich gasoline. ► GeRePt catalyst is suitable to produce a reformate rich in aromatics.Trimetallic Pt–Re–Ge supported catalysts for naphtha reforming were prepared by successive impregnation of suitable precursors on gamma alumina. The order of addition of these precursors was varied and its influence on the catalytic properties was assessed by means of the model reaction of n-octane reforming. It was found that the order of addition of the metal precursors greatly affects the performance and properties of these systems, which in turn is closely related to the first impregnated metal. When platinum is impregnated before rhenium and germanium the metals are reduced separately resulting in catalysts with high dehydrogenation activity and low hydrogenolysis activity. On the other hand, the impregnation of germanium before the other metals leads to the production of catalysts with low activities for dehydrogenation and high activity for hydrogenolysis, as a consequence of the strong interactions among the metals. By adding rhenium before the other metals, catalysts with intermediate behavior are produced. For all catalysts, platinum interacts more strongly with rhenium than with germanium. The order of addition does not modify the acidic properties of the support but germanium and rhenium seem to change the acidity of the support in the vicinity of the metals, causing differences in the selectivity to aromatic compounds and paraffinic isomers. These features can be used to tailor catalysts with high selectivity for the production of aromatics or isoparaffins, depending on the purpose of the reforming process. The RePtGe catalyst has the highest selectivity to branched isoparaffins and then can be used to produce isoparaffins-rich gasoline while a reformate rich in aromatics can be obtained by using the GeRePt catalyst.

Keywords: n-Octane reforming; Trimetallic catalysts; Pt–Re–Ge; Xylenes; Gasoline

Nanocrystalline sodalite: Preparation and application to epoxidation of 2-cyclohexen-1-one with hydrogen peroxide by Norihito Hiyoshi (pp. 164-169).

Display Omitted► Nanocrystalline sodalite with an average diameter of 48nm was synthesized. ► The nanocrystalline sodalite promoted the epoxidation of 2-cyclohexen-1-one with H₂O₂. ► The nanocrystalline sodalite was recovered by filtration after reaction and reused.In this study, we have synthesized nanocrystalline sodalite and investigated its activity for the epoxidation of α,β-unsaturated ketone with hydrogen peroxide. Nanocrystalline sodalite was prepared by hydrothermal synthesis using sodium metasilicate (Na₂SiO₃·9H₂O), sodium aluminate (NaAlO₂), and sodium chloride at 423K. The obtained samples were characterized by X-ray diffraction, the Brunauer–Emmet–Teller (BET) method using nitrogen adsorption isotherms, scanning electron microscopy (SEM), and energy dispersive X-ray analysis. The maximum BET surface area of the nanocrystalline sodalite prepared in this study was 73m²g⁻¹, and the average crystallite diameter of the sample was determined to be 47nm by SEM. Nanocrystalline sodalite was found to promote the epoxidation of 2-cyclohexen-1-one with hydrogen peroxide. Epoxidation was observed to proceed mainly in the liquid phase and not on the surface of the nanocrystalline sodalite, and nanocrystalline sodalite was found to play a role in the pH adjustment of the liquid phase, which was required for the reaction to proceed. Further, nanocrystalline sodalite could be easily recovered by filtration after the epoxidation of 2-cyclohexen-1-one and used repeatedly for the reaction.

Keywords: Sodalite; Nanocrystalline solid; Epoxidation; Electron deficient alkene; Hydrogen peroxide

Synthesis and characterization of FeS nanoparticles obtained from a dithiocarboxylate precursor complex and their photocatalytic, electrocatalytic and biomimic peroxidase behavior by Swarup Kumar Maji; Amit Kumar Dutta; Papu Biswas; Divesh N. Srivastava; Parimal Paul; Anup Mondal; Bibhutosh Adhikary (pp. 170-177).

Display Omitted► FeS NPs by decomposition of a single-source precursor. ► EG, EN and NH₃ have been used as structure directing solvents. ► Effective photocatalytic activity towards the decomposition of MB. ► Biomimic peroxidase behavior of FeS NPs. ► FeSNPs/GC electrode performs excellent amperometric sensor for H₂O₂.Nanorods and nanospheres of FeS with different sizes have been synthesized from a single-source precursor Fe(ACDA)₃ [HACDA=2-aminocyclopentene-1-dithiocarboxylic acid] complex by decomposing it in structure-directing solvents such as ethylene glycol (EG), ethylenediamine (EN) and ammonia (NH₃). The phase purity, morphology, structure and properties of the FeS nanoparticles (NPs) were studied by powder X-ray diffraction, transmission electron microscopy, UV–vis absorption and photoluminescence spectroscopic techniques. The photocatalytic activity of FeS NPs for the degradation of Methylene Blue (MB) has been found to be much better compared to that exhibited by commercial TiO₂. The synthesized FeS NPs showed catalytic activity towards peroxidase substrates 3,3′,5,5′-tetramethyl benzidine (TMB) and H₂O₂, which follows typical Michaelis–Menten kinetics and good catalytic efficiency. Furthermore, the FeS NPs immobilized on glassy carbon (GC) electrode performs as excellent amperometric sensor for the detection of H₂O₂. The FeSNPs/GC electrode showed a linear range for the detection of H₂O₂ from 10 to 130μM with a sensitivity of 26μA/mM and detection limit of 4.03μM.

Keywords: FeS nanoparticles; Photocatalysis; Artificial peroxidases; Electrocatalytic activity; Amperometric biosensors

Tuning double metal cyanide catalysts with complexing agents for the selective production of cyclic carbonates over polycarbonates by Jose Tharun; Manju Mamparambath Dharman; Yeseul Hwang; Roshith Roshan; Moon Seok Park; Dae-Won Park (pp. 178-184).

Display Omitted► Double metal cyanide (DMC) complexes based on (Zn₃[Co(CN)₆]₂) were successfully synthesized. ► Cetyltrimethylammonium bromide (CTAB), tert-butanol and/or PEG–PPG–PEG were used as complexing agents. ► The DMC catalysts were very efficient for the selective production of styrene carbonate over polycarbonate. ► No additional solvent was used for the cycloaddition of carbon dioxide and styrene oxide.A double metal cyanide (DMC) complex based on (Zn₃[Co(CN)₆]₂), an effective catalyst for the ring opening polymerization of epoxides and the copolymerization of carbon dioxide with epoxides, was successfully utilized for the solvent-free cycloaddition of CO₂ to styrene oxide (SO) by the introduction of cetyltrimethylammonium bromide (CTAB) as a complexing agent (CA). Several DMC catalysts were prepared by introducing co-complexing agents (co-CAs) along with the CA. From the XRD data, it was clear that all the catalysts were amorphous with no peak corresponding to the precursor ZnCl₂. XPS analysis was performed to explain the successful introduction of the CA to the DMC catalyst, in which the binding energy of the zinc atom shifted from precursor ZnCl₂ to DMC. Elemental analysis and FT-IR also confirmed the incorporation of the CA with Zn₃[Co(CN)₆]₂. The DMC complex was proven to be an effective catalyst for the solvent-free synthesis of styrene carbonate by the cycloaddition of styrene oxide and CO₂. This paper reports the tunability of the metal cyanide catalysts with CA for the selective preparation of cyclic carbonates over polycarbonates.¹H NMR and FT-IR confirmed product formation. The effects of reaction parameters like catalyst amount, temperature, CO₂ pressure, and reaction time were also investigated.

Keywords: Double metal cyanide; Carbon dioxide; Styrene oxide; Styrene carbonate

Regioselective hydroformylation of vinyl acetate catalyzed by rhodium complex of naphthyl-based monodentate bulky phosphine and phosphite ligands by Aasif A. Dabbawala; Hari C. Bajaj; Ganga V.S. Rao; Sayed H.R. Abdi (pp. 185-193).

Display Omitted► Naphthyl based bulky phosphine and phosphite ligands have been synthesized. ► Nature of ligand and solvent exhibited considerable impact on rate and selectivity. ► Notable TOF and selectivity observed with bulky phosphite in organic carbonates. ► Propylene carbonate allowed easy product separation and catalyst recycling.The hydroformylation of vinyl acetate was carried out using rhodium complex of naphthyl-based monodentate bulky phosphine and phosphite ligands. All the naphthyl-based ligands favored the formation of desire branched aldehyde. High turnover frequency with excellent regioselectivity to branched aldehyde and high selectivity to aldehyde were observed with bulky phosphite ligands. The effect of partial pressure of CO and H₂, concentration of vinyl acetate, stirring rate and solvents on the hydroformylation of vinyl acetate catalyzed by Rh/bulky phosphite were examined precisely in order to improve the catalytic activity and selectivity. In contrast to conventional organic solvents, the significant influence on the activity and selectivity was observed in organic carbonates (‘green’ solvent) particularly in propylene carbonate (PC). The PC/catalyst system could be recycled without significant loss of activity and selectivity.

Keywords: Hydroformylation; Vinyl acetate; Monodentate bulky phosphite; High rate; Regioselective

Epoxidation of trans-stilbene and cis-cyclooctene over mesoporous vanadium catalysts: Support composition and pore structure effect by Zhen Guo; Chunmei Zhou; Shuangquan Hu; Yuanting Chen; Xinli Jia; Raymond Lau; Yanhui Yang (pp. 194-202).

Display Omitted► Dispersed vanadium active sites were deposited in mesoporous channels. ► Epoxidation of bulky compounds was chemical probed in these catalysts. ► Pore size and structure have significant effect on the catalytic properties. ► V-TUD-1 showed the best performances due to its unique 3D mesostructure. ► Suppressed pore diffusion resistance is suggested to be the main factor.Vanadium supported on mesoporous molecular sieve catalysts with different pore diameters and structures (V-MCM-41, V-SBA-15, and V-TUD-1) were synthesized using a post-synthesis grafting method. The physicochemical properties of these as-calcined mesoporous vanadium catalysts were investigated by several techniques including N₂-physisorption, X-ray diffraction, UV–vis, UV–Raman, and X-ray absorption near-edge structure spectroscopies. The characterization results revealed that the vanadium domains were mainly isolated VO₄ units with a distorted tetrahedral coordination. Epoxidation of trans-stilbene and cis-cyclooctene were carried out to determine the influence of pore size and pore structure on the catalytic activity in a liquid-phase reaction. The best catalytic performance was achieved over the V-TUD-1 catalyst. It was suggested that the unique open 3D sponge-like mesostructure of the TUD-1 support can effectively suppress the pore diffusion resistance on bulky reactants and allow the good accessibility of reactants to the active sites embedded on the pore wall surfaces of mesoporous channels.

Keywords: Mesoporous catalysts; Vanadium; Post-synthesis grafting; Epoxidation; Pore size and structure

Liquid phase oxidation of benzyl alcohol with molecular oxygen catalyzed by metal chromites by K. Premalatha; P.S. Raghavan; B. Viswanathan (pp. 203-209).

Display Omitted► Metal chromites of the type MCr₂O₄ (M=Co, Ni, Cu) are synthesized and characterized by various spectroscopic techniques. ► All the catalysts show 100% selectivity towards the oxidation of benzyl alcohol to benzaldehyde. ► CoCr₂O₄ shows higher surface area than the other two catalysts which may attribute to better catalytic activity. ► The catalytic activity of the chromites follows the order Co>Ni>Cu.The spinel type chromites MCr₂O₄ (M=Co, Ni and Cu) were synthesized by the co-precipitation method and have been characterized by a number of analytical tools. The efficacy of the synthesized system as catalysts for the oxidation of benzyl alcohol by molecular oxygen has been studied wherein it has been observed that benzaldehyde is formed with 100% selectivity. The catalytic activity of the chromites follows the order Co>Ni>Cu. The effect of the reaction parameters like the amount of the catalyst and reaction time was studied and it has been observed that the surface area and chemical hardness of the catalysts play a significant role.

Keywords: Spinel; Metal chromites; Selective oxidation; Benzyl alcohol

New and efficient technique for the synthesis of Urapidil using β-cyclodextrin as an inverse phase-transfer catalyst by Wen Li; Wenya Zhang; Xiaoqing Ma; Panpan Wang; Menghong Du (pp. 210-214).

Display Omitted► A highly efficient method for the synthesis of Urapidil has been developed. ► The N-alkylation reaction is very rapid in the presence of an inverse phase transfer catalyst in aqueous media. ► β-cyclodextrin is the best catalyst owing to its excellent catalytic activity and eco-friendly nature. ► The rate constant got in the study coincide with the pseudo-first order rate equation. ► The proposed method is suitable for the industrial scale synthesis of Urapidil.A novel and efficient procedure has been developed for the preparation of Urapidil, (6-({3-4-(2-methoxyphenyl) piperazin-1-yl] propyl} amino)-1,3-dimethyl pyrimidine-2,4-(1H, 3H)-dione), from 6-[(3-chloropropyl) amino]-1, 3-dimethyluracil and 1-(2-methoxyphenyl) piperazine hydrochloride under inverse phase-transfer catalysis (IPTC) conditions. To optimize the reaction conditions, the alkylation reaction was carried out with a range of inverse phase-transfer catalysts, agitation speeds, reaction times, reaction temperatures, mole ratios and catalyst loadings. In addition, the factors affecting the rate of reaction were studied and the rate constant obtained is consistent with the pseudo-first order rate equation. When β-cyclodextrin was used as a catalyst, Urapidil was obtained as a white crystalline powder in 82.6% isolated yield with 99.6% purity after 2–3h reaction in alkaline aqueous media at 95°C with an agitation rate of 1500rpm.

Keywords: Urapidil; β-cyclodextrin; Inverse phase-transfer catalysis; Synthesis

β-pinene oxidation by hydrogen peroxide catalyzed by modified niobium-MCM by Jakelyne V. Coelho; Luiz C.A. Oliveira; Flavia C.C. Moura; Patterson P. de Souza; Cesar Augusto Silva; Kenia Barros Batista; Márcio José da Silva (pp. 215-220).

Display Omitted► It was produced a modified niobia with high catalytic capacity for β-pinene oxidation using hydrogen peroxide. ► β-pinene was efficiently converted into the allylic oxidation products in all reactions. ► The Nb-MCM catalyst can easily be recovered and reused several times.Although solid niobium has a high surface area, its high Lewis and Brønsted acidity is a drawback that always compromises its catalytic performance in oxidation reactions. In this work, treating the niobium catalyst with hydrogen peroxide circumvents this disadvantage and results in a significant increase in the selectivity of the oxidation of β-pinene. In addition, the efficiency of the niobium catalysts supported on MCM was investigated. Nb-MCM//H₂O₂ and Nb-MCM were the most active catalysts. Good selectivity of up to 85% at a 93–97% substrate conversion has been achieved. The catalyst can easily be recovered and reused several times without loss in activity.

Keywords: Niobium; MCM; β-pinene; Hydrogen peroxide

Corrigendum to “Catalytic asymmetric epoxidation of unfunctionalized olefins using a series novel type of layered crystalline organic polymer–inorganic hybrid zinc phosphonate–phosphate immobilized aryldiamine modified chiral salen Mn (III) complex” [Appl. Catal. 407 (2011) 163–172] by Jing Huang; Xiangkai Fu; Qiang Miao (pp. 221-221).

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Applied Catalysis A, General (v.419-420, #)