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Applied Catalysis A, General (v.431-432, #)

Contents (pp. iii-viii).

Editorial Board (pp. co2).

Advances in direct NO_x decomposition catalysts by Nobuhito Imanaka; Toshiyuki Masui (pp. 1-8).

Display Omitted► Direct decomposition of NO_x offers an ideal and reasonable route for NO removal. ► Catalysts for direct NO decomposition into nitrogen and oxygen. ► Cu ion-exchange zeolites, perovskite-type oxides, and rare earth oxides show high NO_x decomposition activities. ► C-type cubic rare earth oxides and their related materials exhibit excellent resistance to O₂ and CO₂.Direct decomposition of nitrogen oxides (NO_x), which are the main air pollutants responsible for photochemical smog and acid rain, into N₂ and O₂ (2NO→N₂+O₂) offers the most ideal route for NO_x removal by catalysis. Direct decomposition of NO_x is versatile and economic because no reductants are required. However, the catalytic activities of conventional catalysts are insufficient, particularly in the presence of other gases such as O₂ and CO₂. In recent years, however, investigation of different catalyst structures and compositions has led to enhanced catalytic activity. In particular, significant advances have been made in improving the tolerance of the catalyst to coexisting gases. These direct NO decomposition catalysts have been designed with a view to maximizing the cavity space and number of oxide anion vacancies in the crystal lattice. In this review article, recent advances in the direct NO decomposition catalysts are summarized.

Keywords: Direct NO decomposition; Zeolites; Perovskite; Rare earth oxide; Cubic C-type structure; Cavity space; Oxide anion vacancy

Sub-ambient CO oxidation over mesoporous Co₃O₄: Effect of morphology on its reduction behavior and catalytic performance by A. Alvarez; S. Ivanova; M.A. Centeno; J.A. Odriozola (pp. 9-17).

Display Omitted► 3 different Co₃O₄ morphologies were synthesized by precipitation and hydrothermal methods. ► The reduction behavior under H₂ flow is strictly correlated to the particle size. ► DRX analysis reveals a preferential exposition of the [110] plane in the Co₃O₄ rods. ► The reduction profile under CO, the OSC and catalytic activity depend on the plane exposition.The influence of the Co₃O₄ morphology on its redox behavior and catalytic performance in the CO oxidation reaction is studied. Three different Co₃O₄ morphologies were synthesized by precipitation and hydrothermal methods. TEM and SEM observations clearly show the different obtained morphologies: rods, wires and a mixture of plates and cubes. The textural properties depend on the morphology and the redox ones on the particle size. XRD analysis reveals a spinel structure in all solids with a preferential exposition of the [110] plane in the Co₃O₄ rods sample. This preferential exposition, along with its higher specific surface area provides the rods with more efficient oxygen storage capacity resulting in an excellent catalytic performance compared to the other two morphologies.

Keywords: Cobalt oxide spinel; Morphology; Plane exposition; Reduction behavior; Low temperature CO oxidation

Microkinetic modeling of Pt-catalyzed ethylene glycol steam reforming by Matthew A. Christiansen; Dionisios G. Vlachos (pp. 18-24).

Display Omitted► A predictive mean-field microkinetic model is developed for steam reforming of ethylene glycol on a Pt catalyst. ► Early dehydrogenation reactions control the reaction rate and OH-assisted reactions do not contribute to the overall rate. ► Steam reforming of ethylene glycol is the superposition of catalytic pyrolysis and water–gas shift reactions. ► The results highlight a kinetic analogy between CH₄ steam reforming and ethylene glycol steam reforming over Pt catalysts.A predictive mean-field microkinetic model is developed for steam reforming of ethylene glycol over a Pt catalyst using a hierarchical multiscale modeling approach. The model's predictive capabilities are assessed by comparison to experimental data under kinetically controlled conditions. It is found that early dehydrogenation reaction steps control the reaction rate, highlighting a kinetic analogy between ethylene glycol steam reforming and CH₄ steam reforming on Pt catalysts.

Keywords: Microkinetic modeling; Platinum; Ethylene glycol; Steam reforming; DFT; BEPs

Study of CuO/CeO₂ catalyst with for preferential CO oxidation reaction in hydrogen-rich feed (PROX-CO) by Cristhiane Guimarães Maciel; Tatiana de Freitas Silva; Luciene Paula Roberto Profeti; Elisabete Moreira Assaf; José Mansur Assaf (pp. 25-32).

.Display Omitted► CuO/CeO₂ catalysts for PROX-CO. ► Redox properties were studied by H₂-TPR-XANES and PROX-CO-XANES. ► Catalysts prepared by hydrothermal methods showed better performance. ► Lower temperatures are favorable for PROX-CO performance.The CuO/CeO₂ system was investigated as a catalyst for preferential CO oxidation reaction in hydrogen-rich feed (PROX-CO). The catalysts were prepared by deposition–precipitation (DEP) and co-precipitation (COP) methods and the catalytic performance reveals that the preparation method influences the properties of solids prepared, where a direct consequence is the difference in behavior of the catalysts in the PROX-CO reaction. A high specific area and a better dispersion of the metallic phase were obtained in the catalyst prepared by co-precipitation. The redox properties during the reaction were reported by measures of temperature programmed reduction (TPR), OSC measurements and X-ray absorption near edge structure (XANES-TPR) in situ showed the relationship between the preparation method, the physico-chemical characteristics and redox properties in the PROX-CO reaction. By this means, the good dispersion of CuO and the best oxygen capacity are the response of the high performance of CuO/CeO₂-COP catalysts for the PROX-CO reaction.

Keywords: CuO/CeO; ₂; Preparation method; Redox properties; XANES

Silica-supported palladium complex: An efficient, highly selective and reusable organic–inorganic hybrid catalyst for the synthesis of E-stilbenes by R.K. Sharma; Amit Pandey; Shikha Gulati (pp. 33-41).

Display Omitted► Silica-supported palladium complex. ► Efficient, recoverable and reusable catalyst with consistent activity. ► Characterizations and application of organic–inorganic hybrid catalyst. ► Selective synthesis of E-stilbenes in microwave via Suzuki-Miyaura cross-coupling reaction.A novel, highly efficient and reusable palladium based catalyst has been synthesized by covalent grafting of diphenyldiketone–monothiosemicarbazone on silica gel followed by metallation with palladium chloride, and the resulting organic–inorganic hybrid material was found to be highly effective catalyst for Suzuki-Miyaura cross-coupling reaction of various aryl halides with alkenyl boronic acid to give stilbenes. The catalyst was characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray fluorescence (ED-XRF), BET surface area analysis, solid-state¹³C CPMAS NMR spectroscopy, atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM) and elemental analysis. High turnover frequency, mild reaction conditions, high selectivity for E-stilbenes, and easy recovery and reusability of the catalyst renders the present protocol highly indispensable to address the industrial prerequisites and environmental concerns.

Keywords: Cross coupling reaction; Reusable catalyst; Silica gel; Immobilization; Microwave; Stilbenes

Enhanced catalytic performance of rare earth-doped Cu/H-Sep for the selective catalytic reduction of NO with C₃H₆ by Qing Ye; Lina Yan; Haiping Wang; Shuiyuan Cheng; Dao Wang; Tianfang Kang; Hongxing Dai (pp. 42-48).

Display Omitted► Cu/H-Sep and RE-Cu/H-Sep; (RE=La, Ce, Pr, Sm) are prepared by impregnation method. ► Doping REO_x to Cu/H-Sep promotes the reducibility and copper oxide dispersion. ► REO_x doping enhances the catalytic performance of Cu/H-Sep in the SCR of NO by C₃H₆. ► Ce-Cu/H-Sep performs the best, giving 62% NO conversion at 350°C. ► Reducibility, CuO dispersion, and synergism determine the catalytic activity.The undoped and rare earth oxide (REO_x, RE=La, Ce, Pr, Sm)-doped acid-treated sepiolite (H-Sep)-supported copper oxide catalysts (Cu/H-Sep and RE-Cu/H-Sep; Cu and RE loading=15 and 4wt%, respectively) were prepared using the incipient wetness impregnation method. The catalysts were characterized by means of the XRD, BET, XPS, H₂-TPR and NH₃-TPD techniques, and their catalytic activities were evaluated for the selective catalytic reduction (SCR) of NO with propylene. It is shown that the doping of REO_x led to an enhancement in catalytic performance of Cu/H-Sep in the SCR of NO with C₃H₆. Among the RE-Cu/H-Sep catalysts, Ce-Cu/H-Sep performed the best, with 62% NO conversion being achieved at 350°C in the (NO+C₃H₆+O₂) reaction. We believe that the high catalytic performance of Ce-Cu/H-Sep for the SCR of NO with C₃H₆ was associated with the good low-temperature reducibility, high copper oxide dispersion, and strong metal–support interaction.

Keywords: Selective catalytic reduction; NO removal; Rare earth oxide dopant; Sepiolite-supported copper oxide catalyst; Metal–support interaction

Precursor influence and catalytic behaviour of Ni/CeO₂ and Ni/SiC catalysts for the tri-reforming process by Jesús Manuel García-Vargas; José Luís Valverde; Antonio de Lucas-Consuegra; Beatriz Gómez-Monedero; Paula Sánchez; Fernando Dorado (pp. 49-56).

.Display Omitted► Silicon carbide as a new support for the tri-reforming process. ► Nickel nitrate, nickel acetate, nickel chloride and nickel citrate as precursors. ► Nickel chloride produces larger particles with a lower interaction with the support. ► Basicity is affected by precursor and support ► H₂/CO ratio is also affected by the support and by the particle size.The aim of the work described here is to evaluate the catalytic performance in the tri-reforming process of Ni/CeO₂ and Ni/β-SiC catalysts prepared by using four different nickel salts (nitrate, acetate, chloride and citrate). Metal particles supported over ceria had bigger particle sizes (leading to lower metal-support interactions) than those supported on β-SiC. It was also demonstrated that the metal salt used in the preparation of Ni-based catalysts had a marked influence on the size of the nickel particles. Larger particles with a worse catalytic behaviour were obtained when nickel chloride and nickel citrate were used as the precursors of Ni supported species. Methane consumption rate and H₂/CO ratio in the effluents were influenced by the type of support and salt precursor used in the preparation of the catalysts. CO₂-TPD proved that catalysts based on ceria as the support presented more basic sites, which was related to a decrease of the H₂/CO molar ratio in the effluents coming from the reactor. High methane consumption rate and good catalytic stability were obtained when nickel nitrate and nickel acetate were used to prepare Ni/β-SiC catalysts. The results showed that these latter catalysts can be considered as promising ones for the tri-reforming process.

Keywords: Methane; Tri-reforming; TPR; TPD; Nickel; Water–gas shift

Electrocatalytic oxidation of allyl alcohol on Pd and Pd-modified Au electrodes in alkaline solution by Changchun Jin; Xijun Sun; Rulin Dong; Zhidong Chen (pp. 57-61).

Display Omitted► Allyl alcohol shows a high reactivity in electrocatalytic oxidation. ► Palladium modification improves catalytic activity of Au electrodes. ► The activity of Pd-modified Au electrodes is dependent on the palladium loading.The electrocatalytic oxidation of allyl alcohol on Pd, Au, Pt, and Pd-modified Au electrodes in alkaline solution has been investigated. The Pd-modified Au electrodes with different amounts of the deposited palladium were prepared by reducing palladium chloride using linear sweep voltammetric method. The results of cyclic voltammetric measurements show an advantage of the Pd electrodes in peak potential and an advantage of the Au electrodes in peak current in allyl alcohol oxidation. However, no catalytic activity of the Pt electrodes is observed. Palladium modification results in a significant improvement in the catalytic activity of the Au electrodes. In allyl alcohol oxidation on the Pd-modified Au electrodes, peak potentials are similar to that obtained on the Pd electrodes and peak currents are depending on the amount of the deposited palladium. The results of chronoamperometric measurements show an improved resistance of the Pd-modified Au electrodes to poisoning.

Keywords: Electrocatalytic oxidation; Allyl alcohol; Palladium; Surface modification; Alkaline solution

Synthesis and photocatalytic properties of nanocrystalline Au, Pd and Pt photodeposited onto mesoporous RuO₂-TiO₂ nanocomposites by Adel A. Ismail; Detlef W. Bahnemann; Saleh A. Al-Sayari (pp. 62-68).

Display Omitted► Noble metals have been photodeposited onto mesoporous RuO₂-TiO₂ photocatalysts. ► Under UV light, Pd/RuO₂-TiO₂ is much than other. ► Under visible light, the photonic efficiency of RuO₂-TiO₂ improved two times by addition Au. ► Pt and Pd could not be improved the photocatalytic activity of RuO₂-TiO₂.Noble metals (Au, Pd and Pt) have been photodeposited onto hexagonal mesoporous RuO₂-TiO₂ nanocomposites to study their influence on the photocatalytic activity under UV and visible lights by determination of the formation rate of HCHO generated by photooxidation of CH₃OH in aqueous solution. X-ray diffraction (XRD) patterns and N₂ sorption isotherms reveal that highly crystalline TiO₂ and mesoporous structure have been formed with high surface area (150–180m²/g) and pore diameter ranging from 6.8 to 7.3nm. TEM measurements show that the framework of the highly crystalline mesoporous RuO₂-TiO₂ is composed of anatase phase grown along [101] direction. The dependence of HCHO formation rate on the noble metals/RuO₂-TiO₂ nanocomposites, behaves quite differently depending on noble metals as electrons sink. Under UV light, the findings reveal that Pd/RuO₂-TiO₂ offers an improvement in term photooxidation rate of CH₃OH and photonic efficiencies over Pt/RuO₂-TiO₂ and Au/RuO₂-TiO₂. However, under visible light, the photocatalytic activity of mesoporous RuO₂-TiO₂ containing Au nanoparticles towards CH₃OH oxidation is remarkable and the photonic efficiency of RuO₂-TiO₂ has been improved two times. Pt and Pd nanoparticles could not be observed in any improvement in photocatalytic activity of RuO₂-TiO₂ under visible light.

Keywords: Noble metals; RuO; ₂; -TiO; ₂; ;Mesoporous; Photooxidation; Methanol; UV and visible light

High-throughput study of the iron promotional effect over Pt/WO_x–ZrO₂ catalysts on the skeletal isomerization of n-hexane by M.L. Hernandez-Pichardo; J.A. Montoya de la Fuente; P. Del Angel; A. Vargas; J. Navarrete; I. Hernandez; L. Lartundo; M. González-Brambila (pp. 69-78).

Display Omitted► Fe as promoter in Pt/WO_x–ZrO₂ catalysts for n-hexane isomerization. ► The study was performed using high-throughput experimentation approaches. ► An optimum Fe/W ratio between 0.05 and 0.07 was found at any tungsten content. ► The tungsten content was optimized by the promotion with iron at low concentrations (0–1% Fe).Pt supported on tungstated zirconia catalysts (Pt/WZ) doped with different Fe contents were evaluated in the n-hexane hydroisomerization reaction. High-throughput experimentation (HTE) approaches were used to investigate the effect of the iron incorporation over the catalytic activity. It was found that the presence of iron at low concentrations (0.5–1wt%) increases the conversion and the yield to the high octane 2,2-dimethyl-butane (2,2-DMB) isomer. The characterization results suggest that the presence of iron modifies the nanostructure of the WO_x species on the zirconia surface which in turn produces the generation of active Brønsted acid sites thus optimizing the tungsten content toward the highest catalytic activity. It was also found that the surfactant incorporation further improves the performance of Pt/WZ catalysts, although, the activity was improved with the Fe addition at lower concentration.

Keywords: Iron promoter; High-throughput experimentation; Tungstated zirconia; Surfactant; n; -Hexane hydroisomerization

Catalytic partial oxidation and steam reforming of methane on La₂O₃–Al₂O₃ supported Pt catalysts as observed by X-ray absorption spectroscopy by K.O. Rocha; J.B.O. Santos; D. Meira; P.S. Pizani; C.M.P. Marques; D. Zanchet; J.M.C. Bueno (pp. 79-87).

Display Omitted► Pt/La₂O₃–Al₂O₃ catalysts were studied by XANES under partial oxidation of methane (POM). ► Pt/La₂O₃–Al₂O₃ catalysts were studied by EXAFS under steam reforming of methane. ► EXAFS data suggested changes in the Pt particle structure with temperature and reactant composition. ► The extinction of the POM reaction occurred at low temperature on metallic Pt sites.Structural transformations of Pt supported on Al₂O₃ or La₂O₃–Al₂O₃ were studied by X-ray absorption near edge structure (XANES) at the Pt L₃ edge during heating and cooling under partial oxidation of methane (POM) conditions, and by extended X-ray absorption fine structure (EXAFS) under steam reforming of methane (SRM) conditions. Ignition of the POM reaction occurred simultaneously with the reduction of PtO₂ to metallic Pt, indicating that the ignition occurs on metallic Pt. When the temperature of the POM reaction was decreased, carbon accumulated on the metallic Pt surface, and the activation of CH₄ was suppressed at about 370°C. Nevertheless, the oxidation of carbon remaining on the metallic Pt surface continued until a temperature of around 270°C was reached, when oxidation of Pt occurred and the oxidation reactions were extinguished. The EXAFS data obtained during SRM and under H₂ suggest that complex alterations in the structure of Pt particles occur with changes of temperature and reactant composition. The SRM activity of Pt catalysts depends on both the access of CH₄ to active Pt sites, and the changes in the structure of Pt particles under reaction conditions. For both reactions, Pt supported on La₂O₃–Al₂O₃ was more stable than Pt supported on Al₂O₃, indicating a higher stability of Al₂O₃ modified with La₂O₃.

Keywords: Pt catalysts; La; ₂; O; ₃; –Al; ₂; O; ₃; oxides; Partial oxidation of methane; Steam reforming of methane; Pt-supported catalysts; In situ; XAFS

Copper nanoparticles stabilized on nitrogen-doped carbon nanotubes as efficient and recyclable catalysts for alkyne/aldehyde/cyclic amine A³-type coupling reactions by Vasanthakumar Ganga Ramu; Ankur Bordoloi; Tharamani C. Nagaiah; Wolfgang Schuhmann; Martin Muhler; Chiara Cabrele (pp. 88-94).

Display Omitted► Metallic copper nanoparticles dispersed on nitrogen-doped carbon nanotubes were prepared. ► The supported nanoparticles were applied as reusable catalysts in A³-type reactions. ► Diastereomerically pure proline derivatives were straightforwardly synthesized.Metallic copper nanoparticles have been efficiently dispersed and stabilized on nitrogen-doped carbon nanotubes. They are about 8–10nm in diameter and highly resistant against bulk oxidation. Their catalytic activity and recyclability have been investigated in A³-type coupling reactions for the synthesis of propargylamines. It was easily possible to prepare diastereomerically pure derivatives of proline and to efficiently recover and reuse the supported catalyst several times.

Keywords: A; ³; coupling; Copper catalysis; Copper nanoparticles; Heterogeneous catalysis; Nitrogen-doped carbon nanotubes

Organometal-bridged PMOs as efficiency and reusable bifunctional catalysts in one-pot cascade reactions by Jianlin Huang; Fang Zhang; Hexing Li (pp. 95-103).

Display Omitted► Bifunctional catalysts were prepared by surfactant-directed co-condensation. ► Organometal incorporated into silica walls of periodic mesoporous organosilica. ► Synergic effect between two kinds of active sites. ► High catalytic efficiency and strong durability in one-pot cascade organic reactions.Two bifunctional catalysts with two kinds of organometals incorporated into the periodic mesoporous organosilica (PMO) supports, denoted as Rh/Pd@PMO(Ph) catalyst and Fe/Cp*Rh@PMO(Et) chiral catalyst, were synthesized by surfactant directed co-condensation between phenyl (Ph)- or ethyl (Et)-bridged and organometal-bridged silanes. Two bifunctional catalysts exhibited high activities and selectivities and even high ee values in one-pot two-step cascade reactions comprised Rh(I)-catalyzed methylenation and Pd(II)-catalyzed Heck reaction, or Fe(III)-catalyzed hydrolysis and Cp*Rh-catalyzed asymmetric hydrogenation. The promoting effects from the ordered mesoporous structure, the coordination model, and the synergic effect between two kinds of active sites were discussed based on the detailed characterizations. Their catalytic efficiencies were comparable with the corresponding homogeneous catalysts and could be easily recycled and used repetitively, which could greatly reduce the cost and diminish the environmental pollutions from heavy metal ions.

Keywords: Bifunction catalysts; Periodic mesoporous organosilicas (PMOs); Organometal-bridged PMO; Surfactant directed co-condensation; One-pot cascade reactions; Asymmetric reaction

Interaction of Zn²⁺ with extraframework aluminum in HBEA zeolite and its role in enhancing n-pentane isomerization by Nur Hidayatul Nazirah Kamarudin; Aishah Abdul Jalil; Sugeng Triwahyono; Rino R. Mukti; Muhammad Arif Ab Aziz; Herma Dina Setiabudi; Mohd Nazlan Mohd Muhid; Halimaton Hamdan (pp. 104-112).

Display Omitted► Zn²⁺ bonded with (AlO)⁺ extraframework aluminum to form Zn(OAl)₂. ► The formation of Zn(OAl)₂ induced the formation of Si(OH)Al. ► The Brønsted acidic center exchanged from (AlO)⁺ to Si(OH)Al. ► Zn²⁺ increased Lewis acid sites and decreased Brønsted acid sites. ► The presence of Zn²⁺ increased the yield of iso-pentane by about 25.7% over HBEA.The electrodeposition method was used to produce Zn²⁺ cation precursors, followed by the introduction of Zn²⁺ cation precursors to HBEA by the ion exchange technique. The introduction of Zn²⁺ cations slightly changed the specific surface area and crystallinity of HBEA. IR, XPS and solid state MAS NMR results showed that Zn²⁺ cations interacted with (AlO)⁺ extraframework aluminum to form Zn(OAl)₂ and simultaneously induced the formation of bridging hydroxyl groups, Si(OH)Al. The pyridine adsorbed IR study revealed that the presence of Zn²⁺ cations fully eliminated weak and partially eliminated strong Brønsted acid sites. As a result, strong and relatively weak Lewis acid sites were formed in which the pyridine probe molecule desorbed at 623K and below. The presence of Zn²⁺ cations enhanced the catalytic activity of HBEA in n-pentane isomerization due to the presence of strong Lewis acid sites; the sites may facilitate the formation and maintenance of active protonic acid sites through a hydrogen spillover mechanism. At 598K, the yield of isopentane for Zn-HBEA was 25.7% higher than that of HBEA. Within a reaction temperature range of 373–648K, the apparent activation energy for isomerization of n-pentane over HBEA and Zn-HBEA was 118.76 and 90.79kJ/mol, respectively.

Keywords: Zn-HBEA; Extraframework aluminum; Bridging hydroxyl groups; Protonic acid sites; n; -Pentane isomerization

Support effects in the aqueous phase reforming of glycerol over supported platinum catalysts by Aysegul Ciftci; Baoxiang Peng; Andreas Jentys; Johannes A. Lercher; Emiel J.M. Hensen (pp. 113-119).

Display Omitted► Alumina, silica and silica–alumina supported Pt tested in aqueous phase reforming of glycerol. ► Alumina-containing supports convert to boehmite under reaction conditions. ► Boehmite formation leads to increased 1,2-propanediol selectivity. ► Pt on boehmite is more active than Pt on alumina or silica.Aqueous phase glycerol reforming was studied for a set of Pt catalysts supported on γ-Al₂O₃, SiO₂ and amorphous silica–alumina (ASA) with varying alumina concentrations. The main products at 225°C under 29barN₂ pressure for a feed of 20wt.% glycerol are H₂, CO₂ and C₁–C₃ alkanes, 1,2-propanediol, hydroxyacetone and C₁–C₃ monoalcohols are the products in the liquid phase. Boehmite formation is observed for the γ-Al₂O₃ and ASA supported catalysts. The higher the Al concentration of ASA, the higher the amount of boehmite. Especially at low Al concentrations, the presence of boehmite is limited and silica leaches from the ASA support under reaction conditions. The increased surface acidity as a result of the presence of boehmite leads to increased hydroxyacetone formation (glycerol dehydration) and 1,2-propanediol (hydroxyacetone hydrogenation) formation. The activity of boehmite supported Pt for hydrodeoxygenation and reforming reactions is higher than that of γ-Al₂O₃ and SiO₂ supported Pt.

Keywords: Glycerol; Aqueous phase reforming; Amorphous silica alumina; Platinum

New life of a forgotten method: Electrochemical route toward highly efficient Pt/C catalysts for low-temperature fuel cells by Igor Leontyev; Aleksandra Kuriganova; Yuri Kudryavtsev; Brahim Dkhil; Nina Smirnova (pp. 120-125).

Display Omitted► We highlight novel, simple route for manufacturing Pt/C catalyst for fuel-cell applications. ► This method based on dispergation of Pt electrodes under pulsed alternating current. ► Activity of prepared Pt/C catalyst is significantly higher than commercially counterpart.Driven by global environmental concerns, great efforts are currently made to develop novel, cheap and practical means for producing highly efficient electrocatalysts, specifically for the low-temperature fuel-cell applications. Employing an old but yet unexplored method based on electrochemical dispergation of platinum by the alternating current, we show that the freshly prepared Pt/C catalysts exhibit greatly enhanced catalytic activity (up to 350% for oxygen reduction and up to 200% for ethylene glycol oxidation) as compared with that of a commercially available counterpart (E-TEK). A key role in these reactions is attributed to a specific nanoparticle morphology. These findings should provide a revival of an ancient but simple and efficient electrochemical process and motivate further researches in the field.

Keywords: Low-temperature fuel cell; Platinum nanoparticles; Electrocatalysis; Oxygen reduction reaction (ORR); X-ray diffraction (XRD); Shape

Investigations of surface VO_x species and their contributions to activities of VO_x/Ti_0.5Sn_0.5O₂ catalysts toward selective catalytic reduction of NO by NH₃ by Lihui Dong; Chuanzhi Sun; Changjin Tang; Bing Zhang; Jie Zhu; Bin Liu; Fei Gao; Yuhai Hu; Lin Dong; Yi Chen (pp. 126-136).

Display Omitted► Vanadium oxide species are highly dispersed and form epitaxial-growth layer on TS support. ► The catalyst with the 1.5mmolV/100m² possesses a maximum amount of Brønsted acid sites. ► Polymeric vanadium oxide species are the primary active species. ► 1.5V/TS catalyst exhibits the best catalytic performance for the “NO+NH₃+O₂” reaction. ► A possible reaction mechanism is proposed on the basis of in situ FT-IR interrogation.High surface area Ti_0.5Sn_0.5O₂ mixed oxide with rutile phase was prepared by a coprecipitation method. The surface area of Ti_0.5Sn_0.5O₂ sample is 76.7m²g⁻¹, and VO_x/Ti_0.5Sn_0.5O₂ catalysts were prepared using the mixed oxide as support. Characterizations using XRD, FT-IR, LRS, EPR, UV–vis, and TEM demonstrated that vanadium oxide species are highly dispersed on the surface of Ti_0.5Sn_0.5O₂ support when the loading amount of vanadium oxide is ≤1.5mmolV/100m² Ti_0.5Sn_0.5O₂. The dispersed vanadium oxide species form epitaxial-growth layer on the support. In situ FT-IR (NH₃ adsorption), combined with NH₃-TPD, indicate that the catalyst with vanadium loading amount of 1.5mmolV/100m² Ti_0.5Sn_0.5O₂, which equals to the dispersion capability, possesses a maximum amount of Brønsted acid sites. The 1.5V/Ti_0.5Sn_0.5O₂ catalyst exhibits the best catalytic performance and good resistance to water vapor poison for the “NO+NH₃+O₂” reaction, indicating that surface dispersed polymeric vanadium oxide species are the primary active species. A possible reaction mechanism is proposed on the basis of in situ FT-IR results.

Keywords: Vanadium oxide; Ti; _0.5; Sn; _0.5; O; ₂; Surface structure; Acidic sites; “NO; +; NH; ₃; +; O; ₂; ” reaction

Effects of iron content on bismuth molybdate for the oxidative dehydrogenation of n-butenes to 1,3-butadiene by Jung-Hyun Park; Hyeryeung Noh; Ji Won Park; Kyoungho Row; Kwang Deog Jung; Chae-Ho Shin (pp. 137-143).

.Display Omitted► β-Bi₂Mo₂O₉ and BiMoFe_x oxide catalysts as catalysts for oxidative dehydrogenation of 1-butene (ODH). ► Fe addition in Bi–Mo oxide catalyst enables to promote catalytic activity. ► Oxygen acceptor Bi₃Mo₂FeO₁₂ and oxygen donor Fe₂(MoO₄)₃ for ODH reaction. ► Yield in 1,3-butadiene could be correlated to the lattice oxygen capacity of the catalyst.BiMoFe_x oxide catalysts ( x=0–1.00) were prepared by co-precipitation and their catalytic activities in the oxidative dehydrogenation of n-butenes were tested. X-ray diffraction (XRD) and Raman spectroscopy showed that the main solid phases were composed of Bi₃Mo₂FeO₁₂ as oxygen acceptor and Fe₂(MoO₄)₃ as oxygen donor and the mixing of these phases enhanced catalytic activity. XRD patterns showed that Fe₂(MoO₄)₃ was reduced to FeMoO₄ during the reaction. The peak temperature of programmed reduction of 1-butene and successive oxidation (TPRO) was dependent on Fe contents in BiMoFe_x oxide catalysts and was minimized at x=0.65, which showed the greatest oxygen mobility. The peak position in the low temperature region of TPRO profiles could be correlated with butene conversion and BD yield.

Keywords: Bismuth molybdenum iron oxide; Oxidative dehydrogenation; n; -Butenes; 1.3-butadiene; Oxygen mobility

Effects of MoO₃ loading and calcination temperature on the activity of the sulphur-resistant methanation catalyst MoO₃/γ-Al₂O₃ by Baowei Wang; Guozhong Ding; Yuguang Shang; Jing Lv; Haiyang Wang; Erdong Wang; Zhenhua Li; Xinbin Ma; Shaodong Qin; Qi Sun (pp. 144-150).

Display Omitted► The catalysts for syngas methanation were studied in the feed containing H₂S. ► Mo–Al/25 catalyst calcined at 600°C had the greatest surface and highest activity. ► The saturated monolayer coverage was proved to be closet to 25wt.% MoO₃. ► Octahedrally coordinated Mo⁶⁺ (O) species was not the active catalytic precursor.The effects of calcination temperature and MoO₃ loading on the syngas methanation performance of MoO₃/γ-Al₂O₃ catalyst prepared by the incipient-wetness impregnation method were studied. Mo–Al/25 catalyst (∼4.04Mo/nm²) calcined at 600°C reached maximum activity with 46.45% CO conversion. All of the experimental results demonstrated that the saturated monolayer coverage of MoO₃ over a γ-Al₂O₃ support was closet to 25wt.% MoO₃. It was discovered that tetrahedrally coordinated Mo⁶⁺ (T), instead of octahedrally coordinated Mo⁶⁺ (O), is the active catalytic precursor in its oxidised state. Additionally, it was also confirmed that the presence of crystalline MoO₃ and Al₂(MoO₄)₃ species depended on not only the MoO₃ loading but also the calcination temperature.

Keywords: Synthetic natural gas; Methanation; Alumina; MoO; ₃; loading; Calcination temperature

Study on methanethiol synthesis from H₂S and dimethyl sulfide over Al₂O₃ catalysts promoted with phosphorus by Shiping Chen; Yuanhua Zhang; Ming Wu; Weiping Fang; Yiquan Yang (pp. 151-156).

.Display Omitted► The DMS was used as a feed to synthesize MT, an important chemical intermediate. ► Phosphorus-modified alumina was applied to the synthesis of MT from H₂S and DMS. ► Phosphorus-modified alumina has a longer life time at 773K than pure alumina. ► The O₂ was added in H₂S feed to inhibit the deactivation at high temperature.A series of P-promoted alumina catalysts with phosphorous contents varying in the range of 1–5% for the reaction of hydrogen sulfide (H₂S) and dimethyl sulfide (DMS) to produce methanethiol (MT) were prepared and characterized by using XRD, SEM, BET, FT-IR and NMR techniques. The activity assay results showed that at the reaction temperature of 593K, the P-promoted alumina catalyst exhibits as high as 100% selectivity toward MT; the DMS conversion ranges from 44.7% to 51.4% depending on the loading of phosphorus. The characterization results showed that introducing a small amount of phosphorus into γ-Al₂O₃ increases the specific surface area, pore volume and the amount of Lewis acid sites. The increase of the Lewis acid sites enhances the capacity of the catalyst to break the CS bond of dimethyl sulfide to methylthiolate (CH₃S⁻) and CH₃⁺, and H₂S adsorbed on alumina to SH⁻ and H⁺, both of CH₃⁺ and H⁺ then interact further with lattice oxygen O²⁻ of the catalyst to form methoxyl (CH₃O⁻) and OH⁻, respectively, subsequent combination of CH₃S⁻ with OH⁻ or CH₃O⁻ with SH⁻ leads to the formation of methanethiol.

Keywords: Phosphorus-promoted alumina; Hydrogen sulfide; Dimethyl sulfide; Methanethiol

Cross ketonization of Cuphea sp. oil with acetic acid over a composite oxide of Fe, Ce, and Al by Michael A. Jackson; Steven C. Cermak (pp. 157-163).

Display Omitted► New ketonization catalyst consisting of a mixed metal oxide. ► Effectively converts Cuphea spp. oil to 2-undecanone upon reaction with acetic acid. ► Selectivity of 90% in a plug flow reactor. ► Leads to a sustainable source of a fragrance compound which is also an effective insect repellent.The objective of this work was to demonstrate the viability of the cross ketonization reaction with the triacylglycerol from Cuphea sp. and acetic acid in a fixed-bed plug-flow reactor. The seed oil from Cuphea sp. contains up to 71% decanoic acid and the reaction of this fatty acid residue with acetic acid yields the fragrance compound and insect repellent 2-undecanone. To this end, we screened several ketonization catalysts taken from the literature including CeO₂, CeO₂/Al₂O₃, CeO₂/ZrO₂, MnO_x/Al₂O₃. The catalysts were characterized by N₂ adsorption/desorption, H₂-TPH, CO₂-TPD, and XRD. Each of these catalysts affected the conversion but the highest yield was found with a new coprecipitated mixed metal oxide of empirical formula Fe_0.5Ce_0.2Al_0.3O_x. In a flow reactor, Fe_0.5Ce_0.2Al_0.3O_x gave 2-undecanone at 91% theoretical yield with reaction conditions of 400°C, weight hourly space velocity of 2, molar ratio of acetic acid to Cuphea oil of 23, and N₂ carrier gas flow of 125ml/min at 2.4bar. This high yield is attributed to the low rate of coke formation on the mixed metal catalyst. In the absence of acetic acid, coupling of the decanoic acid residues gives 10-ketononadecane.

Keywords: Cuphea oil; Ketonization; 2-Undecanone; Insect repellent; Ceria

Ni-modified Mo₂C catalysts for methane dry reforming by Chuan Shi; Anjie Zhang; Xiaosong Li; Shaohua Zhang; Aimin Zhu; Yufei Ma; Chaktong Au (pp. 164-170).

Display Omitted► The presence of Ni could promote the carburization of Mo₂C. ► Ni–Mo₂C catalyst is a typical bi-functional catalyst for CH₄/CO₂ dry reforming. ► A catalytic oxidation–reduction cycle could be established over Ni–Mo₂C (1/2).Dry reforming of methane with CO₂ (DRM) was studied over Ni–Mo₂C catalysts with Ni/Mo molar ratios of 1/3, 1/2, and 1/1 (denoted as Ni–Mo₂C (1/3), Ni–Mo₂C (1/2), and Ni–Mo₂C (1/1), respectively) aiming to investigate the catalytic roles of Ni and the carbide. The results of XRD and XPS characterizations indicated that the carbonization process was promoted by the presence of Ni. The CH₄-TPR and CO₂-TPO over the fresh samples proved that CH₄ dissociation was greatly enhanced by Ni. The Ni–Mo₂C (1/2) catalyst showed the best catalytic activity and stability for CH₄/CO₂ (1/1) dry reforming. Above 80% of CH₄ and CO₂ conversions were maintained at 800°C during a test run of 20h at W/F=0.3gscm⁻³. Characterizations of the spent samples revealed that the deactivation of Ni–Mo₂C (1/1) was due to coke formation whereas that of Ni–Mo₂C (1/3) was due to bulk oxidation of Mo₂C into MoO₂. Only at a Ni/Mo molar ratio of 1/2, a catalytic oxidation–reduction cycle could be established. It was suggested that Ni–Mo₂C was a typical bi-functional catalyst. In CH₄/CO₂ dry reforming, the dissociation of CH₄ was catalyzed by Ni, while the activation of CO₂ took place on Mo₂C. By regulating the molar ratio of Ni and Mo₂C, a catalytic redox cycle could be established.

Keywords: Methane; Carbon dioxide; Molybdenum carbide; Nickel; Dry reforming

Corrigendum to “Hydroformylation of propene heterogeneously catalyzed by HRh(CO)(PPh₃)₃ encapsulated in to hexagonal mesoporous silica—Parametric variation and mass transfer study” [Appl. Catal. A: Gen. 415–416 (2012) 124–131] by N. Sudheesh; Jaydeep N. Parmar; Ram S. Shukla (pp. 171-171).

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Applied Catalysis A, General (v.431-432, #)