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Applied Catalysis A, General (v.382, #1)

Editorial Board (pp. co2).

Contents (pp. iii-vii).

Quantitative study of catalytic activity and catalytic deactivation of Fe–Co/Al₂O₃ catalysts for multi-walled carbon nanotube synthesis by the CCVD process by Sophie L. Pirard; Georges Heyen; Jean-Paul Pirard (pp. 1-9).

The catalytic deactivation during MWNT synthesis by the CCVD process was quantified. The catalytic deactivation was modeled by a decreasing hyperbolic law, reflecting the progressive accumulation of amorphous carbon on active sites. The catalytic deactivation was found to be modified with hydrogen, which delayed and slowed down the deactivation by avoiding amorphous carbon deposition.The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific productivity and catalytic deactivation were studied. Carbon source was ethylene, and a bimetallic iron–cobalt catalyst supported on alumina was used. The catalytic deactivation was modeled by a decreasing hyperbolic law, reflecting the progressive accumulation of amorphous carbon on active sites. While the initial specific reaction rate was found not to be influenced by hydrogen, catalytic deactivation was found to be modified in the presence of hydrogen, which delayed and slowed down the deactivation by avoiding amorphous carbon deposition, thus leading to a greater relative specific productivity of carbon nanotubes.

Keywords: Carbon nanotubes; Catalytic deactivation; Modeling

Structural, acidic and catalytic features of transition metal-containing molecular sieves in the transformation of C₄ hydrocarbon by Alcineia C. Oliveira; Nadine Essayem; Alain Tuel; Jean-Marc Clacens; Younes Ben Taârit (pp. 10-20).

²⁷Al NMR spectra show that silicoaluminophosphates have a large amount of EFAL species that provide Lewis acid sites on hydrothermally synthesized molecular sieves, when combined with EFW Cr₂O₃ and Fe₂O₃. These species, mainly Fe₂O₃, are able to catalyze the transformation of n-butane, in contrast to their analogues, the pure MCM-41 materials.MCM-41 mesoporous materials and silicoaluminophosphates (SAPO-5) were prepared by gel hydrothermal crystallization. Both series of materials were modified by transition metals (chromium or iron close to 1wt%). The synthesized solids were characterized by chemical analysis, XRD, nitrogen adsorption–desorption isotherms, SEM, EPR, XPS, IR of ammonia or pyridine adsorption studies, and²⁹Si,²⁷Al and³¹P NMR. The catalysts were evaluated in the n-butane isomerization in order to assess their properties with regard to alkane transformations. The properties of the solids were modified by adding metals that altered the morphology, structural features and acidic character of the solids and result in an efficient performance in the transformation of n-butane in comparison with the pure counterparts. The introduction of Cr or Fe enhanced the catalytic ability of silicoaluminophosphates to produce isobutane. Fe and Cr modified silicoaluminophosphates were shown to be more efficient in the transformation of n-butane in comparison with the MCM-41 analogues. However, the activity of these iron-containing molecular sieves was considered too low in comparison with performances of iron-modified modernite. This was ascribed to an initial redox C₄ activation step occurring in synergy with Brønsted sites with sufficient acid strength which is indeed higher than that provided by MCM-41 and SAPO molecular sieves.

Keywords: Alkane activation; Acidic measurements; Molecular sieves; Isobutane; NMR; SEM

Catalytic behavior toward oxidative steam reforming of dimethyl ether over CuFe₂O₄-Al₂O₃ composite catalysts by Kajornsak Faungnawakij; Nawin Viriya-empikul (pp. 21-27).

Oxidative steam reforming of dimethyl ether was studied over CuFe₂O₄-Al₂O₃ composite catalysts which showed excellent activity with high H₂ yield as compared with Cu/ZnO/Al₂O₃ and Pd-Zn/Al₂O₃ catalysts. No degradation was observed in the reaction temperature range of 317–335°C for 200h.Oxidative steam reforming of dimethyl ether (DME OSR) for hydrogen production was studied over CuFe₂O₄-Al₂O₃ composite catalysts. The catalytic behaviors of the catalysts were investigated in terms of DME conversion, H₂ production rate, and selectivity to CO₂, CO, and CH₄ as well as the catalyst temperature and gaseous concentration profiles along the catalyst bed. The catalysts exhibited good reforming activity and low CO formation (<2.5vol.%) with trace amounts of other byproducts in the temperature range of 275–375°C, steam/DME of 2.5, and O₂/DME of 0–1. The increase in O₂/DME resulted in improved DME conversion, but lower selectivity to H₂. The catalyst was essentially stable in DME OSR in the 200h stability test in the temperature range of 317–335°C, while H₂ concentration was stably obtained at ca. 62vol.%. Oxygen was rapidly consumed in the beginning zone of the catalyst bed where the exothermic partial oxidation of DME along with CO oxidation would preferentially occur. The majority of reactions in the remaining zone was endothermic steam reforming of DME together with water gas shift reaction.

Keywords: Oxidative steam reforming; Dimethyl ether; Hydrogen; Copper iron spinel; Alumina; Nanocomposite

Effects of zirconia promotion on the structure and performance of smaller and larger pore silica-supported cobalt catalysts for Fischer–Tropsch synthesis by Jingping Hong; Wei Chu; Petr A. Chernavskii; Andrei Y. Khodakov (pp. 28-35).

The effects of zirconia promotion differ considerably with cobalt Fischer–Tropsch catalysts supported by smaller pore MCM-41 and larger pore SBA-15. In CoSBA-15, the promotion did not modify cobalt reducibility, dispersion and catalytic performance. In CoMCM-41, zirconia promotion led to cobalt localization on the outer surface. The activity of CoMCM-41 passes through a maximum as a function of zirconia content.The effects of modification with zirconia on the properties of cobalt species in cobalt Fischer–Tropsch catalysts supported by mesoporous silicas with different porous structures were investigated using nitrogen adsorption, X-ray diffraction, temperature programmed reduction, in situ magnetic measurements and X-ray absorption. The catalysts were prepared by sequential incipient impregnation using solutions of cobalt nitrate and zirconyl nitrate. The effects of zirconia modification on the structure and performance of cobalt based catalysts differ considerably with cobalt catalysts supported by smaller pore MCM-41 and larger pore SBA-15 silicas. In SBA-15 supported samples, modification with zirconia did not result in any significant change in cobalt reducibility and dispersion. Therefore, the concentration of active cobalt metal surface sites on all SBA-15 supported catalysts was comparable, which led to the similar catalytic performance in Fischer–Tropsch synthesis. In MCM-41 supported cobalt catalysts zirconia promotion weakened the cobalt–silica interaction and led to the preferential localization of Co₃O₄ crystallites on the outer surface of the support. Higher zirconia loading led to larger cobalt particles in the zirconia-modified CoMCM-41 catalysts which displayed easier cobalt reduction. The catalytic activity of CoMCM-41 catalysts in Fischer–Tropsch reaction passed through a maximum as a function of zirconia content. The highest activity corresponded to the maximum concentration of cobalt metal sites.

Keywords: Fischer–Tropsch synthesis; Cobalt catalysts; Texture; Zirconia; Mesoporous silica

Methanolysis of sunflower oil using gem-diamines as active organocatalysts for biodiesel production by Miriam Cerro-Alarcón; Avelino Corma; Sara Iborra; Cristina Martínez; María José Sabater (pp. 36-42).

Diamines with neighbour nitrogen atoms were used as base organocatalysts in the methanolysis of sunflower oil. Their catalytic behaviour inversely correlated to their intrinsic basicity, showing that a favourable steric ability to abstract and to release back the proton is necessary for efficient biodiesel production. Besides, a functionalized derivative of the most active diamine seems a promising candidate for heterogeneization.Diamines with neighbour nitrogen atoms have been used as base organocatalysts in the transesterification of sunflower oil with methanol at different temperatures. Several gem-diamines have been studied: dipiperidine-methane (diamine A), di(3-methylpiperidine)-methane (diamine B) and di(3,5-dimethylpiperidine)-methane (diamine C) using a MeOH/oil molar ratio 10/1, in a batch reactor. It has been found that the catalytic activity follows A>B>C, whatever the reaction temperature used. This ranking is inversely correlated to their intrinsic basicity (C>B>A), indicating that for biodiesel production the intrinsic basicity is not the only catalyst factor controlling the activity but the adequate steric ability to abstract and to release back the proton is necessary for an efficient transesterification process. Besides, dipiperidinephenyl-methane, a functionalized derivative of diamine A, has proved to be a promising candidate for heterogeneization.

Keywords: Biomass to fuels; Biodiesel; Transesterification; Alcoholysis; Organocatalysis; Gem; -diamines

Investigation of the packed bed and the micro-channel bed for methanol catalytic combustion over Pt/A1₂O₃ catalysts by Chih-Hsing Leu; Shun-Chih King; Cheng-Chun Chen; Jia-Ming Huang; Shann-Shiuann Tzeng; I-Hung Liu; Wen-Chen Chang (pp. 43-48).

Methanol catalytic combustion processes over Pt/Al₂O₃ catalysts were studied in the packed bed and the micro-channel bed. The IR image of the micro-channel bed revealed that the distribution of the catalytic reaction differed from that of the packed bed. Thus, this study explored the characterizations of the catalyst beds to assist in improving the design of methanol reformer system.On site hydrogen production from methanol steam reforming is an attractive topic for fuel cells. Methanol steam reforming is an endothermic reaction in which the heat can be supplied from methanol catalytic combustion. This study designed similar experimental conditions to compare the differences between the packed bed and the micro-channel bed for methanol catalytic combustion over Pt/Al₂O₃ catalysts. The characteristics of different catalyst beds are examined. These results show that the efficiency of methanol catalytic combustion in the micro-channel bed was superior to that in the packed bed. In the micro-channel bed, the sealed pad creating free space detrimentally affected the efficiency of methanol catalytic combustion, although the space velocity was reduced. The temperature of the IR image on the micro-channel plate of the catalyst bed displayed the temperature of the real reaction status in time.

Keywords: Methanol; Pt/A1; ₂; O; ₃; Catalytic combustion; Packed bed; Micro-channel bed; IR image

Effect of liquid phase reducing agents on the dispersion of supported Pt catalysts by Melanie T. Schaal; Jayakiran Rebelli; Heather M. McKerrow; Christopher T. Williams; John R. Monnier (pp. 49-57).

Silica-supported Pt catalysts were exposed to room temperature, aqueous solutions containing different initial concentrations of formaldehyde, dimethylamine borane, or hydrazine. Platinum sintering was observed upon exposure to each reducing agent. Both Pt/C and Pt/Al₂O₃ catalysts exhibited less sintering upon formaldehyde exposure than that observed for Pt/SiO₂, suggesting a support dependency.Silica-supported Pt catalysts were exposed to room temperature, aqueous solutions containing different initial concentrations of formaldehyde, dimethylamine borane, or hydrazine. Platinum sintering was observed upon exposure to each reducing agent; sintering increased with increasing reducing agent concentration until an apparent, limiting dispersion was achieved. Chemisorption results indicate that exposure of 2.2wt% Pt/SiO₂ to a pH 9 solution containing ∼5.6mmol of hydrazine, formaldehyde, or dimethylamine borane per liter decreased Pt dispersion by ∼30–60%. These results were qualitatively confirmed with STEM and FTIR spectroscopy of adsorbed CO. Sintering of Pt/SiO₂ catalysts was observed in solutions at both controlled (pH 9) and uncontrolled pH for three different Pt weight loadings, and upon exposure to both gas phase and liquid phase reducing agents. Significantly less Pt sintering was observed when Pt/Al₂O₃ and Pt/C catalysts were exposed to similar formaldehyde solutions, strongly suggesting a support dependency. Based on the non-uniform shape of the Pt particles, the prominent sintering mechanism appears to be particle migration and coalescence aided by inherently low Pt–SiO₂ metal-support interactions which were further weakened by the reducing environment and, potentially, by the presence of water.

Keywords: Platinum; Electroless deposition; Liquid phase sintering; Reducing agent

Effect of cobalt precursor on the performance of ceria-supported cobalt catalysts for ethanol steam reforming by Hua Song; Burcu Mirkelamoglu; Umit S. Ozkan (pp. 58-64).

The effect of cobalt precursor on the performance of Co/CeO₂ catalysts in ethanol steam reforming was investigated. The results obtained from steady-state reaction experiments showed a significantly better catalytic performance over the samples prepared by using organometallic Co precursors (especially, cobalt acetyl acetonate). Characterization results suggest a segregation effect for the Co species when they are bound to organic ligands, affecting dispersion and stability.The effect of cobalt precursor on the performance of Co/CeO₂ catalysts in ethanol steam reforming was investigated. The catalysts were characterized using various characterization techniques including H₂ chemisorption, temperature-programmed reduction, temperature-programmed desorption, X-ray diffraction, transmission electron microscopy, and diffuse reflectance infrared Fourier transform spectroscopy. The results obtained from steady-state reaction experiments showed a significantly better catalytic performance over the samples prepared by using organometallic Co precursors (especially, cobalt acetyl acetonate). Characterization results suggest that the organic ligands bound to the cobalt species might facilitate its dispersion on the surface of the CeO₂ support, resulting in the improved activity and stability.

Keywords: Cobalt catalyst; Ceria; Ethanol steam reforming; Cobalt precursor

Alkaline treatment on commercially available aluminum rich mordenite by Adri N.C. van laak; Robert W. Gosselink; Sophia L. Sagala; Johan D. Meeldijk; Petra E. de Jongh; Krijn P. de Jong (pp. 65-72).

Several commercially available samples consisting of agglomerated small mordenite crystallites with low Si/Al ratios (5.7–10at/at) have been treated in aqueous NaOH solution. Upon alkaline treatment inter- and intra-crystalline mesoporosity was introduced, resulting in enhanced accessibility and thereby improving the catalytic performance.Several commercially available samples consisting of agglomerated small mordenite crystallites with low Si/Al ratios (5.7–10at/at) have been treated in aqueous NaOH solution. It was found that the porosity can be enhanced when the sodium hydroxide solution is sufficiently concentrated. Treatment in 1M NaOH for 15min resulted in inter-crystalline porosity and the mesopore volume was increased from 0.01 to 0.21cm³g⁻¹ together with an increased external surface area from 36 to 85m²g⁻¹. The micropore volume and crystallinity were preserved after the treatment. Both H-MOR and Na-MOR mordenite agglomerates have been successfully treated: the Na-MOR requires a longer contact time to obtain similar porosity. By carefully choosing the alkaline concentration and contact time, intra-crystalline mesoporosity can be obtained for mordenite with Si/Al ratios as low as 10. Catalytic tests with proton mordenite showed that alkaline treatment leads to more than one order of magnitude of activity gain in the liquid-phase alkylation of benzene with propene to form cumene, while selectivity is preserved. These results demonstrate that alkaline treatment also on high-aluminum content mordenites is an effective tool to enhance accessibility and thereby its catalytic performance.

Keywords: Mordenite; Mesoporosity; Desilication; Alkylation; Catalysis

An investigation of the role of Zr and La dopants into Ce1− x−_yZr_xLa_yO_δ enriched γ-Al₂O₃ TWC washcoats by A. Papavasiliou; A. Tsetsekou; V. Matsouka; M. Konsolakis; I.V. Yentekakis (pp. 73-84).

Composite TWCs of γ-alumina promoted with ceria based solid solution and Pt (0.5wt%) as the only active phase varying in the solid solution composition (Ce_xZr_yLa_zO_δ), are comparatively investigated. Doping ceria with Zr and La cation proved beneficial for both catalytic performance and thermal durability of the washcoat, with Ce_0.4Zr_0.5La_0.1O_1.9/γ-Al₂O₃/Pt sample presenting the optimum properties.This work involves the synthesis of composite three-way catalytic (TWC) washcoats consisting of 80wt% of γ-alumina as the main supporting material, promoted with 20wt% of ceria based solid solution. Pt in low loading (0.5wt%) was employed as the only active phase. Washcoats varying in the solid solution composition (Ce_xZr_yLa_zO_δ), prepared by coprecipitation, are comparatively investigated in an attempt to elucidate the effect of Ce, Zr and La oxide promoters on the catalytic activity and thermal durability. For this purpose, catalytic activity measurements as well as detailed structural and morphological evaluations (differential thermal analysis (DTA), X-ray diffraction (XRD), N₂ adsorption, oxygen storage capacity and DRIFTS analyses) were carried out before and after thermal aging in oxidative atmosphere. The catalytic performance was studied in loaded cordierite monoliths (TWCs form) under simulated exhaust conditions at the stoichiometric point. Doping ceria with Zr and La cation proved beneficial for both catalytic performance and thermal durability of the washcoat, with Ce_0.4Zr_0.5La_0.1O_1.9/γ-Al₂O₃/Pt sample presenting the optimum properties. The catalytic behavior is discussed based on oxygen storage capacity, noble metal dispersion and textural characteristics of the examined samples.

Keywords: TWCs; Alumina; Ceria; Thermal stability; Simulated exhaust conditions

Homogeneous catalysis in the preparation of new carboximide-based thermoplastic polymers by Sevil Çetinkaya; Taner Özker (pp. 85-89).

The applicability of organometallic catalyst (PCy₃)₂(Cl)₂RuCHPh as initiator in the ring opening metathesis polymerization (ROMP) of norbornene dicarboximide derivatives bearing halo-substituted phenyl groups has been investigated. The synthesis and polymerization of exo-N-4-chlorophenyl-norbornene-5,6-dicarboximide (ClPhNDI), exo-N-4-bromophenyl-norbornene-5,6-dicarboximide (BrPhNDI) and exo-N-4-iodophenyl-norbornene-5,6-dicarboximide (IPhNDI) are reported. All of the prepared polymers were soluble in common organic solvents.The ring opening metathesis polymerization (ROMP) of norbornene dicarboximide derivatives3(a–c) bearing halo-substituted phenyl groups was carried out with well-defined organometallic catalyst (PCy₃)₂(Cl)₂RuCHPh. This catalyst is highly active for the polymerization of norbornene dicarboximide derivatives. Exo-N-4-chlorophenyl-norbornene-5,6-dicarboximide (ClPhNDI,3a), exo-N-4-bromophenyl-norbornene-5,6-dicarboximide (BrPhNDI,3b), exo-N-4-iodophenyl-norbornene-5,6-dicarboximide (IPhNDI,3c) monomers gave high molecular weight thermoplastic polymers in high yields (77–96%). All of the prepared polymers were soluble in common organic solvents at room temperature and gave similar IR and NMR spectra. Their glass transition temperatures were detected at temperatures over 187°C. The surface properties of ROMP polymers were investigated by SEM.

Keywords: Organometallic catalyst; Ruthenium alkylidene; Polynorbornene dicarboximide; Metathesis; ROMP

Heterogeneous Baeyer–Villiger oxidation of cyclic ketones using tert-BuOOH as oxidant by Buddhadeb Dutta; Sreyashi Jana; Susmita Bhunia; Hisashi Honda; Subratanath Koner (pp. 90-98).

Sn(salen)Cl₂ complex was encapsulated into zeolite (NaY) matrix by a template synthesis method. The Sn(salen)-NaY catalyst has been characterized by UV–vis, infrared (IR) spectroscopy, X-ray diffraction, Mössbauer spectra, and¹¹⁹Sn MAS NMR studies. The catalyst shows high catalytic activity in Baeyer–Villiger oxidation of various cyclic ketones. Recycling of the catalyst shows no major change in its catalytic efficacy.The [Sn(salen)]²⁺ complex moiety has been immobilized into NaY zeolite by in situ synthesis of the salen complex in NaY matrix to prepare a new catalyst, Sn(salen)-NaY. The catalyst has been characterized by UV–vis, infrared (IR) spectroscopy, X-ray powder diffraction, Mössbauer and¹¹⁹Sn NMR spectroscopy. The catalyst shows impressive catalytic performance (with high selectivity) in Baeyer–Villiger oxidation of various cyclic ketones including 2-adamantanone, cyclohexanone, cyclopentanone, 4-methylcyclohexanone, 2-methylcyclohexanone using tert-butyl hydroperoxide ( tert-BuOOH) as an oxidant. The yield of ɛ-caprolactone from catalytic oxidation of cyclohexanone over Sn(salen)-NaY catalyst was ca. 75%. The catalyst can be recycled for several times without any major decline in catalytic activity.

Keywords: Heterogeneous catalytic oxidation; NaY zeolite; Sn(salen)Cl; ₂; Immobilization; Baeyer–Villiger oxidation

Mesoporous nickel oxides as effective catalysts for oxidative dehydrogenation of propane to propene by Jian-Hui Li; Cai-Cai Wang; Chuan-Jing Huang; Yi-Fei Sun; Wei-Zheng Weng; Hui-Lin Wan (pp. 99-105).

Mesoporous NiO prepared by a surfactant-assisted route has been proved to be catalytically active and selective for oxidative dehydrogenation of propane to propene. With this catalyst, an optimum propene yield of 13.2% was obtained at 450°C. The characterization results demonstrate that the densities of O⁻ species and cation vacancies are much higher for this meso-NiO catalyst.Mesoporous NiO catalysts prepared by a surfactant-assisted route have been investigated in the oxidative dehydrogenation of propane (ODHP) to propene; these catalysts are compared with two other NiO samples prepared by homogeneous precipitation and sol–gel method, respectively. Mesoporous NiO is proven to be an active and selective catalytic material with an optimum propene yield of 13.2% by the 25.8% propane conversion at 450°C. The propene selectivity remains around 50% in the temperature range from 400 to 550°C. XRD, N₂ adsorption, TEM, O₂-TPD, XPS and Raman characterizations have been used to study the intrinsic differences among these NiO catalysts. The results demonstrate that the densities of O⁻ species and cation vacancies are much higher for the meso-NiO than for other samples; this difference is related to their different catalytic performances. Besides this, the efficient molecular transport by diffusion in the mesoporous channels also plays an important role during the ODHP reaction.

Keywords: Mesoporous; NiO; Oxidative dehydrogenation; Propane; Propene

Metallocene catalyst supported on silica–magnesia xerogels for ethylene polymerization by Rodrigo Brambilla; Cláudio Radtke; Fernanda C. Stedile; João H.Z. Dos Santos; Márcia S.L. Miranda (pp. 106-114).

A series of supported metallocene catalysts were prepared by grafting of Cp₂ZrCl₂ on silica–magnesia xerogels and evaluated in ethylene polymerization. The Cp₂ZrCl₂/SiO₂–MgO systems presented higher catalyst activity in comparison to that resulting from the metallocene grafted on bare silica and it allowed the activation using combination of TEA:MAO, employing low Al content.A series of supported metallocene catalysts were prepared by grafting Cp₂ZrCl₂ on silica–magnesia xerogels, and then they were evaluated for the process of ethylene polymerization. The supports were characterized by a set of complementary techniques including small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and N₂ adsorption–desorption. The supported catalysts were characterized by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance infrared spectroscopy (DRIFTS). The use of silica–magnesia xerogels for immobilization of metallocene yielded systems with higher catalyst activity when compared to the results from metallocene grafted on bare silica. The resulting polymers showed a broader molecular weight distribution than those obtained by homogeneous Cp₂ZrCl₂ and Cp₂ZrCl₂/SiO₂, which potentially provides a better processing capacity of these alternative polyethylenes. In the case of polyethylene obtained with the system containing 16.0wt.% Mg/Si, a fiber-like morphology was observed.

Keywords: Metallocene; Support; Silica–magnesia; Sol–gel; Polyethylene

The heterogenation of melamine and its catalytic activity by Farook Adam; Kasim Mohammed Hello; Hasnah Osman (pp. 115-121).

The melamine molecule has been immobilized onto silica to form RHAPrMela. The nitrogen atoms were believed to be involved in the reaction mechanism for the esterification of ethyl alcohol with acetic acid. Several other alcohols were also studied with the same catalyst. A conversion of 73% was achieved with 100% selectivity for the respective esters.The immobilization of melamine (Mela) onto silica extracted from rice husk ash (RHA) has been done via 3-chloropropyltriethoxysiline (CPTES). The resulting catalyst was designated as RHAPrMela. The melamine loading on the silica was found to be ca. 65.74%. The²⁹Si MAS NMR showed the presence of T², T³, Q³ and Q⁴ silicon centers. The¹³C MAS NMR showed that RHAPrMela had three chemical shifts at 14.83, 31.17 and 52.24ppm, consistent with the three carbon atoms, and two chemical shifts at 161.52 and 169.67ppm with double spinning side bands, indicating that the three carbon atoms in melamine ring are not equivalent in RHAPrMela. The catalytic potential of RHAPrMela was tested for the esterification of acetic acid with several alcohols. A conversion of 73% was achieved with 100% selectivity for the respective esters. The catalyst was easily regenerated and could be reused many times without loss of catalytic activity.

Keywords: Surface modification; Silica surface; Sol–gel technique; Melamine; Esterification

3D solid carbon foam-based photocatalytic materials for vapor phase flow-through structured photoreactors by Shabnam Hajiesmaili; Sébastien Josset; Dominique Bégin; Cuong Pham-Huu; Nicolas Keller; Valérie Keller (pp. 122-130).

3D solid carbon foams were used as support designing efficient vapor phase flow-through structured photoreactors with low-pressure drops. The foam-structured photoreactor benefits from an increased surface to reactor volume ratio and by the static mixer effect induced by the foam. Gas phase methanol oxidation was chosen as target reaction.3D solid carbon foams were used as support for preparing photocatalytic materials working in a traversing-flow mode and designing efficient vapor phase flow-through structured photoreactors. The carbon foams were obtained by resin polymerization and pyrolysis treatments starting from a three-dimension structured reticulated polyurethane foam used as a pre-shaped precursor. The 3D solid carbon foam supported TiO₂ photocatalysts were characterized in terms of morphology, pressure drop, light transmission ability and static mixer role, and using the vapor phase methanol UV-A photocatalytic oxidation as target reaction. The foam-structured photoreactor benefits from a strong gain of exposed surface leading to an increased surface to reactor volume ratio with a large increase in the TiO₂ amount inside the reactor. Further, the improved air-to-surface contact probability ratio induced by the static mixer effect of the foam resulted in a high methanol conversion obtained at a given TiO₂ amount in the reactor. The potential of this 3D-structured photocatalytic material for flow-through photoreactors targeting real applications was also highlighted by induced ultra-low-pressure drops resulting from a high porosity and a large cell size morphology.

Keywords: Photocatalysis; Structured reactors; Carbon foam; Static mixer; TiO; ₂

Aerobic oxidation of alcohols over carbon nanotube-supported Ru catalysts assembled at the interfaces of emulsion droplets by Xiaomin Yang; Xiuna Wang; Jieshan Qiu (pp. 131-137).

Carbon nanotube (CNT)-supported ruthenium catalysts, assembled at the interfaces of emulsion droplets, show excellent activity, selectivity, and stability for the selective oxidation of a variety of alcohols with oxygen or air as oxidant. After the reactions, the catalysts can be easily separated and recycled by sedimentation.Carbon nanotube (CNT)-supported ruthenium catalysts, assembled at the interfaces of emulsion droplets, show excellent activity, selectivity, and stability for the selective oxidations of benzyl alcohol to benzaldehyde with oxygen or air as oxidant in the presence of water. The selective oxidation of benzyl alcohol over Ru/CNTs catalysts is greatly enhanced and quickened due to the presence of water. A reaction pathway is proposed, in which the promotion effect of water on the catalytic activity of Ru/CNTs is discussed. The as-made Ru/CNTs catalysts are also active for the aerobic oxidation of a variety of alcohols with a sulfur or nitrogen atom or a carbon–carbon double bond in the multiphase reaction system. Moreover, after the reactions, the catalysts can be easily separated and recycled by sedimentation.

Keywords: Aerobic oxidation; Alcohols; Carbon nanotubes; Ru; Emulsion catalysis

Corrigendum to “Oxidative functionalisation of lignin by layer-by-layer immobilised laccases and laccase microcapsules” [Appl. Catal. A: Gen. 372 (2010) 115–123] by Claudia Crestini; Raffaella Perazzini; Raffaele Saladino (pp. 138-138).

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Applied Catalysis A, General (v.382, #1)