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Applied Catalysis A, General (v.397, #1-2)

Editorial Board (pp. co2).

Contents (pp. iii-xi).

Renewable fuels via catalytic hydrodeoxygenation by T.V. Choudhary; C.B. Phillips (pp. 1-12).

Display Omitted► HDO of triglyceride based feeds: stand-alone and co-processing. ► HDO of bio-oils from high pressure liquefaction and pyrolysis process. ► Research gaps.There is considerable interest in investigating the deoxygenation process, due to the high oxygen content of the feed-stocks used for the production of renewable fuels. This review addresses studies related to the catalytic hydrodeoxygenation of two feed-stocks (a) oils with high content of triglycerides and (b) oils derived from high pressure liquefaction or pyrolysis of biomass. Future research directions that could potentially bridge the existing gaps in these areas are provided.

Keywords: Bio-fuels; Deoxygenation; Renewables; Pyrolysis oils; Triglycerides

Pillared H-MCM-36 mesoporous and H-MCM-22 microporous materials for conversion of levoglucosan: Influence of varying acidity by M. Käldström; N. Kumar; T. Heikkilä; D.Yu. Murzin (pp. 13-21).

Display Omitted► Transformation of levoglucosan was investigated over zeolites and mesoporous materials. ► H-MCM-36 with different acidities were synthesized, characterized and tested. ► The effect of pillaring on the test reaction was investigated. ► Glycolaldehyde was the main oxygenated species formed.Catalytic transformation of levoglucosan (1-6-anhdyro-β-d-glucopyranose) was carried out in a fixed bed reactor at 573K over H-MCM-22 and pillared H-MCM-36 with different acidities. The yield of the products, phases and product distribution was influenced mainly by the acidity of the zeolite catalysts. Oxygenated species were the main liquid product, consisting foremost of aldehydes and furfural. The formation of the liquid products was higher over MCM-36 pillared materials than over MCM-22 for all the oxygenated species except acetone. The deactivation due to coking was less severe over the pillared materials compared to the microporous precursor. However, it was possible to successfully regenerate the spent zeolites without changing the structure.

Keywords: Pillared; Zeolite; MCM-36; Levoglucosan

XANES-PCA analysis of Ti-species in MCM-41 mesoporous silica synthesized by different method by Oscar A. Anunziata; Andrea R. Beltramone; Maria L. Martinez; Lisandro J. Giovanetti; Felix. G. Requejo; Eduardo Lede (pp. 22-26).

Display Omitted► Ti-species grafted in the mesoporous of MCM-41 synthesized by different method. ► In situ and ex situ Ti-K-XANES study in combination with PCA and ITFA study. ► A complete determination about the kind and concentration of each Ti-species. ► By hydrothermal synthesis, Ti-MCM-41 has the majority of Ti tetrahedral-coordinated. ► In the case of the sol–gel synthesis, Ti-sites have higher average coordination.MCM-41 mesoporous silica was prepared with Ti incorporated in the structure by two different ways: hydrothermal and atmospheric pressure by sol–gel method. To evaluate each synthesis, these materials were in situ investigated through X-ray absorption fine structure (XAFS) spectroscopy in different stages of the synthesis. X-ray absorption structure at the near edge region (XANES) gives the coordination of Ti and the relative concentration of Ti-species present in the mesoporous materials, obtained by different synthesis. The Principal Component Analysis (PCA) of XANES spectra indicate that mesoporous silica modified by Ti synthesized by hydrothermal method has species with majority of Ti tetrahedrally coordinated. This coordination is increased up to six when the sample is hydrated. In the case of the sol–gel synthesis, Ti-sites have higher mean coordination, independently from the degree of hydration.

Keywords: Ti-K-XANES; PCA/ITFA; Ti-MCMC-41; Hydrothermal synthesis; Sol–gel procedure

Organic–inorganic hybrid polyoxometalates: Efficient, heterogeneous and reusable catalysts for solvent-free synthesis of azlactones by Mahbubeh Rostami; Ahmadreza Khosropour; Valiollah Mirkhani; Majid Moghadam; Shahram Tangestaninejad; Iraj Mohammadpoor-Baltork (pp. 27-34).

Display Omitted► Adding ionic liquid to H₃PW₁₂O₄₀ and K₄W₁₀O₃₂. ► Heterogeneous catalysts were prepared. ► These catalysts were active in the synthesis of azlactones. ► Makes the catalyst reusable.Two organic–inorganic hybrid polyoxometalates, consist of 1-butyl-3-methylimidazolium salts of (W₁₀O₃₂)⁴⁻ and (PW₁₂O₄₀)³⁻ polyanions were prepared and characterized by thermal analysis, X-ray diffraction, FT-IR, diffuse reflectance UV–Vis spectroscopic methods and nitrogen absorption–desorption determination (BET). These heterogeneous catalysts were used for synthesis of azlactones by the reaction of aldehydes with hippuric acid and acetic anhydride under solvent-free conditions. These catalysts were reused several times without loss of their activities.

Keywords: Hybrid polyoxometalate; Heterogeneous catalysts; Azlactone; Solvent-free

Spatio-temporal features of periodic oxidation of H₂ and CO on Pt/CeO₂/Al₂O₃ by Yi Liu; Michael P. Harold; Dan Luss (pp. 35-45).

.Display Omitted► Infrared imaging detects complex spatio-temporal patterns during the H₂ and CO reduction of Pt/CeO₂/alumina monolith catalyst. ► Reliance on the effluent concentration of reacting species does not capture the rich dynamics. ► Transient oxidation of CO is enhanced by H₂.Infrared measurements reveal that cyclic shifts between lean and rich (H₂ and/or CO) feeds to a Pt/CeO₂/Al₂O₃ monolith catalyst generate complex, spatio-temporal temperature features. A sharp temperature rise occurs in the upstream of the monolith shortly after the cyclic introduction of either H₂/CO to a pre-oxidized catalyst or O₂ to a pre-reduced catalyst. This initial upstream temperature rise following the reduction of oxygen stored on a pre-oxidized catalyst is higher than following the oxidation of either H₂ or CO (or their mixture) stored on the monolith. The upstream hot zone temperature decreases with time without forming a downstream moving temperature front. The intricate transient temperature gradients are caused by a competition between the chemical and transport rate process. However, the effluent concentrations do not reflect these complex interactions. Only about 20% of the total oxygen trapped during the pre-oxidation with a 5% O₂/N₂ mixture at 350°C is strongly bound or chemisorbed. Most of the oxygen that reacts at high temperature is loosely-bound. The introduction of a nitrogen sweep flow between the lean and rich feeds removes a significant amount of the loosely held oxygen, leading to a much more uniform reduction. Inadequate resolution of the spatio-temporal phenomena may lead to a misinterpretation of the apparent kinetics. The spatial features of the thermal fronts of the two reductants (CO or H₂) are similar. The amplitude of the hot spot of the two reactants differ due to differences in the temperature dependencies of their oxidation rates. The transient oxidation of CO/H₂ mixtures reveal H₂ enhanced CO oxidation is likely due to a kinetic interaction as seen in previous steady-state studies.

Keywords: Cyclic operation; Storage/release; Monolith catalyst; Hydrogen; Platinum; Ceria; Infrared imaging; Spatio-temporal temperature

Experimental and theoretical properties of S–Mo–Co–S clusters by D.H. Galvan; Francis Leonard Deepak; Rodrigo Esparza; A. Posada-Amarillas; R. Núñez-González; X. López-Lozano; M. José-Yacamán (pp. 46-53).

Our research provides evidence for the existence of S–Mo–S, S–Mo–Co–S and S–Mo–Co–S with rotated planes nano wires. This evidence was proved by means of High Resolution Transmission Electron Microscopy as shown in the following figure. The S–Mo–S, S–Mo–Co–S and S–Mo–Co–S with rotated planes yielded semi metallic to the first two structures and metallic behavior to the last one..Display Omitted► MoS₂ samples were prepared and characterized by High Resolution Transmission Microscopy. ► The samples showed existence of S–Mo–S, S–Mo–Co–S and S–Mo–Co–S with rotated planes. ► Theoretical analysis was performed on such structures showing semi metallic behavior. ► A hybridization was manifested for three structures under study. ► The nano wires are 1T-MoS₂ configuration, the metal are not in a trigonal prismatic environment.In this work we propose that certain structures found in real commercial catalysts may be related to low dimensional structures. These structures are S–Mo–S and S–Mo–Co–S nanowires which were characterized by High Resolution Scanning Transmission Electron Microscopy (HR-STEM), Electron Diffraction (ED) and Electron Dispersive X-ray analysis (STEM-EDAX). Furthermore, a structural model was constructed with the one dimensional structures in order as to investigate their electronic properties. Energy band analysis on the samples yield indication about the semi metallic behavior, while a careful analysis to the partial Density of States (PDOS) in the vicinity of the Fermi level, provided indication for the existence of strong hybridization between S p- with Mo d- and Co d- and p-orbitals for the samples enunciated formerly. In addition, a very important issue to be mentioned is that in the construction of the 1T-S–Mo–Co–S nanowires, the Co and Mo atoms are not in their pure trigonal prismatic environment as compared to the bulk 2H-MoS₂. This issue could be deleterious for future catalytic applications.

Keywords: Dehydrodesulfurization; Tight-binding; Nanowires; Catalyst

Procedure to tailor activity of methane combustion catalyst: Relation between Pd/PdO_x active sites and methane oxidation activity by Niko M. Kinnunen; Janne T. Hirvi; Tapani Venäläinen; Mika Suvanto; Tapani A. Pakkanen (pp. 54-61).

Display Omitted► An improved PdO_x/Al₂O₃ methane combustion catalyst is presented. ► Acid concentration plays a key role in the preparation. ► Pd/PdO_x ratio is used to tune the combustion activity. ► NH₃ TPD and XRD have are used to correlate activity with surface species.The paper describes a new way to tune the activity of PdO_x/Al₂O₃ catalyst—by adjusting the concentration of the impregnation solvent. The effect of tuning on aging was investigated.Catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Surface properties of the catalysts were measured by Brunauer–Emmett–Teller (BET), NH₃ desorption (NH₃–TPD), and CO pulse chemisorption methods. The activities in methane combustion were measured under lean burn conditions.Activity of the supported catalyst was successfully optimized by adjusting the concentration of carboxylic acid in the impregnation solution. The results showed that the activity of the catalyst is related to the Pd/PdO_x ratio as measured by NH₃–TPD method. The results also indicated that low light-off temperature is obtained when the proper proportion of PdO_x is able to transform to metallic Pd during heating. The catalyst reconstruction during aging caused the amount of PdO sites to increase and, thereby, some loss of catalyst activity.

Keywords: Methane combustion; Acetic acid; Propionic acid; Palladium; PdO; Alumina; NH; ₃; –TPD

Silicon carbide foam composite containing cobalt as a highly selective and re-usable Fischer–Tropsch synthesis catalyst by Maxime Lacroix; Lamia Dreibine; Benoit de Tymowski; Fabrice Vigneron; David Edouard; Dominique Bégin; Patrick Nguyen; Charlotte Pham; Sabine Savin-Poncet; Francis Luck; Marc-Jacques Ledoux; Cuong Pham-Huu (pp. 62-72).

Display Omitted► Medium surface area SiC and Al₂O₃/SiC foam for use as catalyst support. ► High effective surface area and low pressure drop foam catalyst support. ► Active cobalt-based catalyst for the Fischer–Tropsch synthesis reaction with high selectivity for liquid hydrocarbons. ► Easy recovery of both the cobalt active phase and the SiC support by a simple acid washing. ► Complete re-usable support.The Fischer–Tropsch synthesis was evaluated on cobalt based catalyst supported on a medium surface area SiC foam ceramic in a fixed-bed configuration. The catalytic results were compared with those obtained on a Co/Al₂O₃ foam catalyst. At medium conversion (<50%) the two catalysts display similar C₅₊ selectivity indicate that the intrinsic selectivity between the two catalysts is close from each other. However, when the CO conversion was increased to 70%, a significant difference in terms of the C₅₊ selectivity was observed between the two catalysts, i.e. 80% on the Co/SiC and 54% on the Co/Al₂O₃, which indicate that under severe FTS reaction conditions the SiC seems to be more suitable support than alumina. It is also worth to note that under these reaction conditions the chain length probability, α, obtained on the SiC-based catalyst was 0.91 and wax formation was especially favoured. The improvement of the C₅₊ selectivity observed on the SiC catalyst was attributed to the high efficiency of the support to evacuate heat generated during the course of the reaction owing to it higher thermal conductivity and also to the presence of meso- and macro-porosity of the support. Additional catalytic test conducted on a hybrid support, i.e. Al₂O₃ coated SiC foam, again confirms the high C₅₊ selectivity under a similar severe reaction conditions in the presence of a SiC structure underneath of the alumina layer which play a role of heat disperser. In addition, the high chemical inertness of the SiC material also allows one to perform an easy recovery of both the active phase and the support by a simple acid washing. The recovered SiC support was further impregnated with a fresh cobalt phase and re-tested in the FTS and the catalytic results are compared with those of the former catalyst. The same product yield was obtained which confirms the potential of SiC to be employed as a re-usable support.

Keywords: Silicon carbide; Alumina; Fischer; Tropsch synthesis; Catalyst recovery; Support recovery

Synthesis of MWCNTs and hydrogen from ethanol catalytic decomposition over a Ni/La₂O₃ catalyst produced by the reduction of LaNiO₃ by Jaime Gallego; German Sierra; Fanor Mondragon; Joël Barrault; Catherine Batiot-Dupeyrat (pp. 73-81).

.Display Omitted► High yields of H₂ and CNTs are produced by ethanol decomposition over Ni/La₂O₃. ► H₂, different gasses and CNTs yields depend on reaction conditions. ► Carbon nanotubes are of multi-wall-type. ► CNTs properties depend on reaction conditions. ► CNTs defects induce changes in the intershell spacing.In the present paper we present a clean process that allows the simultaneous production of hydrogen and carbon nanotubes based on catalytic decomposition of ethanol, which is a renewable energy source. The catalyst consists of Ni nanoparticles highly dispersed on La₂O₃, obtained by the reduction of LaNiO₃. The effect of reaction conditions, such as reaction temperature and ethanol heating temperature, on the gaseous composition of the produced gas and the characteristics of the carbonaceous deposits was studied. An increase of the reaction temperature leads to an increase in H₂ production. The carbonaceous deposits were characterized by TGA, Raman spectroscopy TEM and HRTEM analysis. TEM micrographs show that the nanotubes were multi-walled with inner diameters ranging from 4nm to 12nm and outer diameters up to 75nm. At low reaction temperatures the production of fibers is favored. The best graphitized carbon material was obtained when ethanol reacts at the surface of the catalyst instead of products issued from the thermal decomposition of ethanol (CH₄, CO, CO₂, C₂H₆ and C₂H₄). The yield of carbon nanotube (CNT) and H₂ were 3.5g_CNT(g_cath)⁻¹ and39 LH2(gh)−1 respectively at 700°C. The inner diameter of the CNTs does not depend on the experimental conditions used, whereas the outer diameter strongly depends on the reaction temperature (from 500°C to 700°C). From HRTEM images two types of carbon materials were shown: one with parallel graphene layers and one with fishbone structure. The intershell spacingsdˆ002 were measured, the average value was equal to 0.344nm for parallel tubes, while in curvature the d spacing is higher: 0.360nm.

Keywords: Ethanol; MWCNTs; Hydrogen; Perovskites; Nickel

Effect of the particle size and surface area of tungstated zirconia on the WO_x nuclearity and n-heptane isomerization over Pt/WO₃–ZrO₂ by Dalibor Kaucký; Blanka Wichterlová; Jiri Dedecek; Zdenek Sobalik; Ivo Jakubec (pp. 82-93).

Display Omitted► The effect of zirconia and WO_x nuclearity on n-heptane isomerization was analyzed. ► UV–Vis gave analysis of four types of WO_x of different nuclearity on various zirconia. ► The most active are small two dimensional poly-WO_x species with 35000cm⁻¹ band. ► Nanosize hydrous zirconia yields highly active small poly-WO_x at low W content.Four series of tungstated zirconia of different surface area ranging from 100 to 20m²g⁻¹ and of micro- and nano-meter crystal size were investigated with respect to nuclearity and reducibility of WO_x species, concentration of strong and weak acid sites, and n-heptane isomerization over Pt/WO₃–ZrO₂. The nuclearity of WO_x species was analyzed by diffuse reflectance UV–Vis spectroscopy and their reducibility by TPR-H₂. TPD of ammonia distinguished acid sites of different strengths. n-Heptane isomerization proceeds over Pt/WO₃–ZrO₂ in hydrogen/nitrogen mixture at 250°C. At least four types of WO_x species differing in nuclearity were identified in tungstated zirconia by a maxima of absorption at 39000, 35000, 30000 and 27000cm⁻¹, intensity of which depended on the surface area, crystal size and WO₃ loading. From the changes in the relative intensities of the characteristic individual bands of WO_x species with tungsten loading, at different surface area and crystal size, it follows that at the lowest loading mononuclear W–O–Zr species (39000cm⁻¹) and two-dimensional poly-tungstate like WO_x species (35000cm⁻¹) are formed, which are at loading above a nominal monolayer started to transform into a larger defined WO_x, likely tri-dimensional clusters (30000cm⁻¹). The absorption maximum at 27000cm⁻¹ corresponds to bulk-like WO₃. The nuclearity of WO_x species was reflected in their reducibility, which increased with increased nuclearity, and it was higher for the nano-size tungstated zirconia. The isomerization activity followed the relative population of poly-tungstate WO_x species (35000cm⁻¹), but was not in strict agreement with the concentration of strong acid sites. This might be connected with the rate determining step of the isomerization process or formation of radical cations depending on reaction conditions. The nano-size tungstated zirconia exhibited high isomerization activity advantageously at low W loading (6–12wt.%) compared to the micro-meter size ones. This finding corresponds to formation of poly-tungstate WO_x species already at low loadings, likely at the defective sites of the nano-size zirconia.

Keywords: n-Heptane isomerization; Pt/WO; ₃; –ZrO; ₂; Nano ZrO; ₂; WO; _x; clusters; UV–Vis spectra WO; _x

Oxadiazoline and ketoimine palladium(II) complexes supported on a chitosan membrane and their catalytic activity for the microwave-assisted Suzuki–Miyaura cross-coupling in water by Jamal Lasri; Tatiana C.O. Mac Leod; Armando J.L. Pombeiro (pp. 94-102).

Display Omitted► Chitosan supported Pd catalysts for microwave-assisted Suzuki–Miyaura couplings in water. ► High catalytic activity even in the presence of lower catalyst loadings in comparison with other supported palladium sources. ► Effects of catalyst loading, temperature, time, phase-transfer agent and base were investigated. ► Environmentally friendly microwave protocol.The fused bicyclic Δ⁴-1,2,4-oxadiazoline trans-(▪) palladium(II) complex 1 (R= p-ClC₆H₄), in refluxing chloroform, undergoes N–O bond cleavage of the oxadiazoline ring to furnish the new ketoimine palladium(II) complex trans-(▪) 2 bearing the 4-chloro-N-(5,5-dimethylpyrrolidin-2-ylidene)benzamide ligands. Complexes 1 (R=Me) and 2 (R= p-ClC₆H₄) were immobilized on a chitosan membrane and the systems acted as supported-catalysts (Pd-chit 1 and Pd-chit 2, respectively) for the model microwave-assisted Suzuki–Miyaura cross-coupling reactions in water using p-bromoanisole and phenylboronic acid to give p-methoxybiphenyl in excellent yield. The effects of catalyst loading, temperature, time, the phase-transfer agent tetrabutylammonium bromide (TBAB) and base were investigated, and the supported catalyst was recovered and reused up to seven times, with a gradual loss of catalytic activity.

Keywords: Palladium(II) complexes; Chitosan membrane; Catalysts; Suzuki–Miyaura cross-coupling reaction; Water; Microwaves; Recycle

Ozonized activated carbon as catalyst for MTBE-cleavage by A. Nau; S. Kohl; H.-W. Zanthoff; H. Wiederhold; H. Vogel (pp. 103-111).

Display Omitted► The catalytic activity of the oxidized activated carbon can be traced back to the surface groups generated by ozonization. ► Carboxylic acid and anhydride groups are responsible for the activity of oxidized carbon. ► In contrast to commonly used amorphous alumosilicates, the modified carbon inhibited the production of the by-product dimethylether. ► MTBE cleavage is Broensted-acid catalyzed.The application of oxidized carbon materials for the cleavage of methyl-tert-butyl ether has been investigated under technical relevant conditions in a fully automated apparatus with paralleled tube reactors. The carbon spheres oxidized for 60min (SAC60) are active for MTBE cleavage at 498K and 6bar(g). MTBE is selectively converted into isobutene ( S>99%) and MeOH ( S>99.9%) at 80% conversion. The catalytic activity of the oxidized activated carbon can be traced back to the surface groups generated by ozonization of the carbon as the untreated sample did not show any conversion of MTBE at all. Broensted acidic carboxylic acid and anhydride surface groups are responsible for the activity of oxidized carbon as was concluded from simulation of the ex situ DRIFT spectra of the applied materials. In contrast to commonly used amorphous alumosilicates, the modified carbon completely inhibited the production of the undesired by-product dimethylether. Therefore, as no Lewis-acid sites are present on SAC60 and none of the present surface groups (carboxylic acids, anhydrides, lactones and carbonyl groups) cause the dehydration of methanol into dimethylether, it can be concluded that DME formation most probably occurs purely on Lewis-acidic or on basic sites. The decrease in conversion over time-on-stream obtained for the oxidized carbon material is ascribed either to poisoning of present active sites or to a decarboxylation of the activated carbon.

Keywords: MTBE cleavage; Broensted-acidity; Activated carbon; DRIFTS; Oxygen surface groups

Photodeposition of gold on titanium dioxide for photocatalytic phenol oxidation by M.C. Hidalgo; J.J. Murcia; J.A. Navío; G. Colón (pp. 112-120).

Display Omitted► Influence of photodeposition parameters on phenol photooxidation. ► Light intensity and deposition time high influence on gold deposits on TiO₂. ► Low light intensity allowed a feasible method for Au–TiO₂ with high photoactivity.The influence of experimental conditions during the photodeposition in the preparation of supported Au on TiO₂ has been studied. Besides preparation pH, light intensity and deposition time showed to have a high influence on the final properties of gold deposits.Photodeposition using illumination with a high light intensity UV–vis lamp (140W/m² UVA range) resulted to be an ineffective method for obtaining nanoparticles of gold on the titania, producing very large and poorly distributed gold deposits. Thus obtained materials did not show any important improvement of their photocatalytic activity tested for phenol oxidation.By contrast, photodeposition using a low light intensity of illumination (0.15W/m² UVA range), produced materials with notably improved photocatalytic activity. The illumination with such a low light intensity allowed the control of the amount, aggregation and oxidation state of gold by changing deposition time, enabling a feasible method of tailoring Au–TiO₂ with the appropriate properties for a high photocatalytic activity.Best photocatalytic behaviour for phenol photodegradation was obtained for Au–TiO₂ samples prepared by photodeposition at low light intensity with 120min photodeposition time for catalysts with a 0.5% and 1% nominal content of gold and with 60min photodeposition time for catalyst with a 2% nominal content of gold.

Keywords: Photocatalysis; Au/TiO; ₂; Gold; Photodeposition; Light intensity; Phenol photodegradation

Gold nanoparticles supported on cerium(IV) oxide powder for mineralization of organic acids in aqueous suspensions under irradiation of visible light of λ=530nm by Hiroshi Kominami; Atsuhiro Tanaka; Keiji Hashimoto (pp. 121-126).

Display Omitted► Gold (Au)/cerium oxide (CeO₂) samples were prepared by the photodeposition method. ► Au/CeO₂ showed absorption at ca. 550nm due to surface plasmon resonance of Au. ► Formic acid, oxalic acid and acetic acid were stoichiometrically decomposed to CO₂. ► A green light-emitting diode ( λ=530nm) can be used as the light source. ► Apparent quantum efficiency of formic acid mineralization reached 4.7%.Gold (Au) nanoparticles supported on cerium(IV) oxide (CeO₂) were prepared by the photodeposition method. These samples showed strong absorption at around 550nm due to localized surface plasmon resonance (LSPR) of Au. These Au/CeO₂ samples were used for mineralization of organic acids (formic acid, oxalic acid and acetic acid) in the aqueous suspensions under irradiation of visible light (>ca. 520nm) and three acids were stoichiometrically decomposed to carbon dioxide. Apparent activation energy for mineralization of formic acid was very small (2.4kJmol⁻¹) compared with those by thermocatalytic reactions, and the action spectrum was in good agreement with the photoabsorption spectrum, indicating that the rate-determining step in mineralization of organic acids in the irradiated Au/CeO₂ system was different from the thermal activation process and that this mineralization involved a photoinduced step by LSPR of Au supported on CeO₂. When a green light-emitting diode (center wavelength=530nm) was used as the light source of visible light, mineralization of formic acid also occurred. Apparent quantum efficiency of formic acid mineralization increased with decrease in the intensity of the green light and reached 4.7% at 0.4mWcm⁻².

Keywords: Photocatalyst; Gold nanoparticles; Cerium(IV) oxide; Mineralization of organic acids; Visible light; Localized surface plasmon resonance

The role of Ni species in the deoxygenation of rapeseed oil over NiMo-alumina catalysts by Peter Priecel; David Kubička; Libor Čapek; Zdeněk Bastl; Petr Ryšánek (pp. 127-137).

Display Omitted► NiMo-alumina catalysts were prepared with different distribution of Ni species. ► NiMo-alumina catalysts were tested in the deoxygenation of rapeseed oil. ► Conversion increased with increasing Ni(Oh):Ni(Td) population ratio. ► C₁₈/C₁₇ selectivities ratio increased with decreasing Ni(Oh):Ni(Td) population ratio.The deoxygenation of rapeseed oil has been studied over sulfided NiMo-alumina catalysts (NiMoS-alumina). The main focus has been on the preparation of catalyst precursors (oxide form of sulfided NiMo-alumina catalysts – NiMoO-alumina) with a different distribution of Ni species in order to contribute to the understanding of the effect of catalyst preparation on the activity/selectivity of NiMoS-alumina catalysts in the deoxygenation of rapeseed oil. To analyze the state of Ni species the NiMoO-alumina catalysts have been characterized by UV–vis diffuse reflectance spectrometry (DRS), X-ray diffraction (XRD) and XPS. It has been found out that the NiMoO-alumina catalysts with higher population of octahedral nickel species resulted in more active NiMoS-alumina catalysts than those containing higher population of tetrahedral nickel species.

Keywords: Deoxygenation; NiMo-alumina; UV–vis; XRD; XPS; Ni species; Temperature pretreatment; Hydrotreating

Synthesis of NiO–MgO–ZrO₂ catalysts and their performance in reforming of model biogas by Yvan J.O. Asencios; Jorge D.A. Bellido; Elisabete M. Assaf (pp. 138-144).

Display Omitted► The NiO–MgO and the MgO–ZrO₂ solid solutions were obtained. ► The addition of MgO stabilized the tetragonal phase of zirconia and originated oxygen vacancies. ► Solid solutions help to increase the activity of catalysts. ► Oxygen vacancies seems to promote removal of the carbon deposited. ► NiO–MgO–ZrO₂ catalysts are active in model biogas reforming.Catalysts containing NiO/MgO/ZrO₂ mixtures were synthesized by the polymerization method in a single step. They were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR) and physisorption of N₂ (BET) and then tested in the reforming of a model biogas (1.5CH₄:1CO₂) in the presence of air (1.5CH₄+1CO₂+0.25O₂) at 750°C for 6h. It was observed that the catalyst Ni20MZ performed better in catalytic processes than the well known catalysts, Ni/ZrO₂ and Ni/MgO, synthesized under the same conditions. The formation of solid solutions, MgO–ZrO₂ and NiO–MgO, increased the rate of conversion of reactants (CH₄ and CO₂) into synthesis gas (H₂+CO). The formation of oxygen vacancies (in samples containing ZrO₂ and MgO) seems to promote removal of the coke deposited on the nickel surface. The values of the H₂/CO ratio were generally found to be slightly lower than stoichiometric, owing to the reverse water–gas shift reaction occurring in parallel.

Keywords: NiO–MgO–ZrO; ₂; catalysts; Polymerization method; Reforming reaction; Model biogas; Synthesis gas

Nanocrystalline gold supported on Fe-, Ti- and Ce-modified hexagonal mesoporous silica as a catalyst for the aerobic oxidative esterification of benzyl alcohol by Luciana A. Parreira; Nina Bogdanchikova; Alexey Pestryakov; T.A. Zepeda; Inga Tuzovskaya; M.H. Farías; Elena V. Gusevskaya (pp. 145-152).

Display Omitted► The one-port aerobic oxidative esterification of benzyl alcohol was studied. ► Nanoparticles of gold supported on hexagonal mesoporous silica promote this reaction. ► The modification of the support with Ti, Fe or Ce improves the catalytic performance. ► Ce and Ti modified materials show high catalytic activity, selectivity and stability. ► Methyl benzoate was obtained in a 92% yield with a turnover number of ca. 4300.The materials containing gold nanoparticles supported on pure and Ce, Ti, or Fe-modified hexagonal mesoporous silica were prepared and their structural and electronic properties were studied by XRD, TEM, XPS, and N₂ adsorption techniques. The materials were shown to be effective heterogeneous catalysts for the liquid-phase aerobic oxidation of benzyl alcohol in methanol solutions. It was found that the modifiers significantly improve the catalytic properties of supported gold particles and allow performing the selective one-pot oxidative esterification of benzyl alcohol resulting in methyl benzoate. The modified catalysts exhibited high activity (turnover frequencies of up to ca. 1000h⁻¹), selectivity to methyl benzoate (up to 95%), and stability (turnover numbers of up to ca. 4300). Ce and Ti were found to be more effective promoters as compared with Fe in terms of catalyst stability.

Keywords: Oxidative esterification; Benzyl alcohol; Gold supported catalysts; Mesoporous metallosilicates

Improved hydrothermal stability of niobia-supported Pd catalysts by Hien N. Pham; Yomaira J. Pagan-Torres; Juan Carlos Serrano-Ruiz; Dong Wang; James A. Dumesic; Abhaya K. Datye (pp. 153-162).

Display Omitted► Pd/niobia for conversion of γ-valerolactone (GVL) to pentanoic acid (PA). ► Correlation between loss of surface area of niobia support and Pd sintering. ► Silica addition to niobia leads to partial retention of the open, porous structure. ► Silica-modified niobias preserve a higher amount of acid sites after GVL reaction. ► Control over Pd sintering is the crucial factor for improving catalytic stability.Aqueous-phase reactions at elevated temperatures can cause significant loss of surface area in oxide supports. Addition of a second component can help improve the hydrothermal stability of the support and retain a more open, porous structure. Here we show that small amounts of silica (5wt%) help improve the activity and stability of Pd/niobia–silica catalysts used for pentanoic acid formation from γ-valerolactone. At the end of the run, the Pd/Nb–Si oxide catalysts showed significantly higher activity than catalysts where the Pd was deposited on commercial niobia (HY-340). Loss of surface area occurred for all of the catalysts; however, surface area loss occurred to lesser extents for the Pd/Nb–Si oxide catalysts. In these samples, the regions that contained more silica retained their porous structure and maintained smaller Pd crystallite sizes after reaction while those areas with depleted silica content transformed into crystalline niobia along with significant metal particle growth. We conclude that addition of silica to niobia not only improves the stability of the support but also helps retain smaller crystallite sizes for the Pd phase, resulting in improved catalytic performance in the bi-functional aqueous-phase conversion of γ-valerolactone into pentanoic acid.

Keywords: Niobia; γ-valerolactone; Pentanoic acid; High surface area; Hydrothermal stability

Promoted activity of the selective catalytic reduction of NO_x with propene by H₂ addition over a metal-monolithic anodic alumina-supported Ag catalyst by Yu Guo; Jian Chen; Hideo Kameyama (pp. 163-170).

Display Omitted► A metal-monolithic anodic alumina-supported Ag catalyst was used. ► Hydrogen was added to promote the SCR activity at low temperatures. ► The addition of H₂ greatly promoted nitrate decomposition to free silver sites. ► An electrical-heating pattern gave a quick SCR system response.The effect of H₂ addition on the selective catalytic reduction of NO_x with propene (C₃H₆-SCR of NO_x) was investigated using a metal-monolithic anodic alumina-supported Ag catalyst. The de-NO_x activity of the Ag/Al₂O₃ catalyst at low temperature was markedly enhanced by the addition of a small amount of H₂; the enhancement was associated with the improved propene activation at low temperatures. The addition of H₂ greatly promoted the nitrate decomposition at low temperatures, which was believed to alleviate nitrate poisoning and to initiate the SCR reaction at low temperatures, because of the formation of free silver sites. Furthermore, it is suggested that a small amount of H₂ addition will further reduce the freed Ag⁺ species into Ag_n δ⁺ and will eventually lead to the improved de-NO_x activity, because Ag_n δ⁺ is more active for the propene activation than Ag⁺ at low temperatures. However, excess H₂ and high Ag loading mainly promoted the nonselective combustion of propene with oxygen, rather than the selective oxidation of propene with NO_x. Additionally, a combination of this H₂ promotion effect and electrical heating produced a favorable de-NO_x system with a quick response, a wide temperature-window and a high de-NO_x activity.

Keywords: C; ₃; H; ₆; -SCR; NO; _x; reduction; Silver; Anodic alumina catalyst; Hydrogen addition

Effect of Pt addition to Ru–Sn/Al₂O₃ catalyst on hydrogenation of methyl laurate by Shin-ichi Taniguchi; Takahiko Makino; Hiroko Watanuki; Yu-uki Kojima; Makoto Sano; Takanori Miyake (pp. 171-173).

Display Omitted► Hydrogenation of methyl laurate was studied on Ru–Sn/Al₂O₃ and Ru–Sn–Pt/Al₂O₃. ► Without Pt, elution of Sn species during the reaction was observed. ► Addition of Pt promoted reduction of Sn species and reduced elution of Sn species. ► Pt addition resulted in the better stability of the catalyst.Hydrogenation of methyl laurate was studied using the binary Ru–Sn and the ternary Ru–Sn–Pt catalysts, both supported on Al₂O₃. The catalysts were suspended in neat methyl ester, and the reaction was carried out at 300°C and 9.15MPa (Gauge pressure) of H₂ in an autoclave. The catalysts were prepared by the conventional co-impregnation method and characterized by XRD and nitrogen adsorption–desorption isotherm. Elution of metals during the reaction was measured by ICP. Under the adopted reduction conditions of the catalyst precursor, not all the Sn species were reduced to Sn metal; our study revealed that a part of SnO₂ dissolved during the reaction. The addition of Pt to Ru–Sn/γ-Al₂O₃ promoted reduction of the Sn species, prevented the elution of Sn and gave a higher catalytic performance.

Keywords: Hydrogenation; Ruthenium; Tin; Platinum; Methyl laurate; Elution

Modeling the simultaneous oxidation of CO and H₂ on Pt – Promoting effect of H₂ on the CO-light-off by W. Hauptmann; M. Votsmeier; H. Vogel; D.G. Vlachos (pp. 174-182).

Display Omitted► Microkinetic model to simulate the promoting effect of H₂ on the CO oxidation on Pt. ► Coupling of the CO and the H₂ oxidation sub-mechanisms. ► Carboxyl path is crucial to describe the process. ► Estimated parameters are in accordance with experimental values. ► Developed mechanism is thermodynamically consistent.A microkinetic model is developed to simulate the promoting effect of H₂ on the light-off of CO oxidation on platinum. It is shown that the coupling of the CO and the H₂ oxidation sub-mechanisms, via the hydroxyl intermediate and its reaction with CO to carboxyl, is crucial to describe the process. This carboxyl-path was not considered in previous modeling studies.

Keywords: CO oxidation; H; ₂; oxidation; Promotion; Pt; Microkinetic model; Light-off; Carboxyl-path

LaFeO₃-supported nano Co-Cu catalysts for higher alcohol synthesis from syngas by Y.Z. Fang; Y. Liu; L.H. Zhang (pp. 183-191).

Display Omitted► Strong interactions between Co₃O₄ and the support exist in Co₃O₄/LaFe_0.7Cu_0.3O₃. ► Co₃O₄/LaFe_0.7Cu_0.3O₃ can be reduced to Cu-Co or Cu@Co/La₂O₃-LaFeO₃. ► Co in Cu-Co or Cu@Co/La₂O₃-LaFeO₃ can be carbonized to Co₂C during reaction. ► Co₂C is the active site to higher alcohol synthesis. ► Cu-Co₂C/La₂O₂CO₃-LaFeO₃ catalyst possesses high activity and good stability.To produce Co-Cu catalysts supported on perovskite-type oxides of LaFeO₃, we prepared LaFe_0.7Cu_0.3O₃ according to the citrate complexation method; the impregnation method was used to load cobalt oxide onto the support. The Co₃O₄/LaFe_0.7Cu_0.3O₃ catalysts were characterized by XRD, TEM, TPR, XPS and S_BET analysis, and were used to catalyze the synthesis of alcohol from syngas. Copper ions in the perovskite lattice were easily segregated by pre-reduction, which resulted in the formation of nano-sized copper metal. The copper nano-particles catalyzed the reduction of Co₃O₄, which led to the production of highly dispersed copper nano-particles covered by a metallic cobalt shell of core–shell structure Cu@Co and Cu-Co alloy supported on perovskite-type oxides of LaFeO₃. During the reaction, Cu-Co and La₂O₃ facilitated the formation of Co₂C, and the phase of the catalyst precursor changed to Co₂C-Cu/La₂O₂CO₃-LaFeO₃. The prepared catalysts were highly active, selective and stable during the synthesis of alcohol from syngas. The high activity and selectivity of the catalysts were attributed to the presence of copper-modified Co₂C species, which were highly dispersed nano-particles located on the LaFeO₃ surface. The good stability of the catalysts was attributed to the interactions between Co₂C-Cu nano-particles and their support.

Keywords: Higher alcohols synthesis; Stability; Perovskite; Cu-Co; Syngas

Adsorption and degradation performance of Rhodamine B over BiOBr under monochromatic 532nm pulsed laser exposure by Mohammed Ashraf Gondal; Xiaofeng Chang; Mohammad Ashraf Ali; Zain Hassan Yamani; Qin Zhou; Guangbin Ji (pp. 192-200).

.Display Omitted► The BiOBr photocatalyst was synthesized at our laboratory. ► The structures of BiOBr before/after photochemical reaction were determined by XRD. ► The adsorption/degradation of RhB under 532nm pulsed laser exposure were studied. ► The effects of BiOBr dosage/pulsed laser energy on dye removal were investigated. ► It was proved the dissolved O₂ plays a key role in the photodegradation of RhB.The adsorption (under dark condition) and photodegradation behaviors of Rhodamine B molecules on BiOBr under visible (532nm) pulsed laser exposure were studied and reported for the first time. The adsorption kinetics/isotherm behaviors and thermodynamic process (adsorption dynamical parameters) occurred on as-prepared BiOBr were investigated. The photodegradation mechanisms, effects of BiOBr dosage and pulsed laser energy on dye removal efficiency in the presence of BiOBr particles were studied as well. Furthermore, the photodegradation of other kinds of Rhodamine dyes such as Rhodamine 6G, Sulforhodamine B and Sulforhodamine 640 were initially investigated and compared under 532nm pulsed laser exposure. The study also demonstrated that the dissolved oxygen plays a very significant role in the photo-catalytic decomposition of Rhodamine. The BiOBr catalyst was found intact even under acidified conditions showing good stability of the catalyst.

Keywords: BiOBr; Photodegradation; 532; nm-pulsed-laser; Sorption; Rhodamine B

Flame spray synthesis of CoMo/Al₂O₃ hydrotreating catalysts by Martin Høj; Kasper Linde; Thomas Klint Hansen; Michael Brorson; Anker Degn Jensen; Jan-Dierk Grunwaldt (pp. 201-208).

Display Omitted► Preparation: CoMo on alumina catalysts prepared from Co–Mo–Al-precursor solution by flame synthesis. ► One step synthesis results in mostly γ-alumina, some CoAl₂O₄ spinel and XRD-amorphous MoO₃. ► High surface area due to 5–10nm sized oxide nanoparticles. ► Catalysis: excellent hydrotreating activities similar to those of impregnated catalysts. ► Flame synthesis is a promising method for preparation of hydrotreating catalysts.The first alumina supported and unsupported cobalt molybdenum hydrotreating catalysts have been prepared by one-step flame spray pyrolysis (FSP) by spraying and combusting tris(acetylacetonato)aluminum, cobalt 2-ethylhexanoate and molybdenum 2-ethylhexaoate dissolved in toluene. The oxide particles produced contained varying amounts of transition metals (8, 16, 24 and 32wt.% Mo with atomic ratio Co/Mo=1/3 and 16wt.% Mo with atomic ratios Co/Mo=2/3 and 1/1) with alumina constituting the balance. In addition, an unsupported reference catalyst (atomic ratio Co/Mo=1/3) was produced. The particles obtained consisted mostly of γ-Al₂O₃ with some CoAl₂O₄, as evidenced by X-ray diffraction (XRD) and UV–vis spectroscopy. Bulk MoO₃ was not detected by XRD, except at the highest molybdenum content (32wt.%) and in the unsupported sample, indicating that molybdenum is well dispersed on the surface of the support. The specific surface area as measured by nitrogen adsorption (BET) decreased from 221 to 90m²/g when going from the lowest loading supported catalyst (8wt.%) to the unsupported reference. Transmission electron microscopy (TEM) images showed that at low molybdenum loadings nanoparticle agglomerates with 5–10nm primary particles were produced. As the molybdenum loading on the alumina was increased from 8 to 32wt.% and for the unsupported reference the primary particle size increased to up to 20nm and the morphology became more irregular due to primary particle sintering and aggregation.After activation by sulfidation the activity of the catalysts were measured for the three hydrotreating reactions hydrodesulfurization, hydrodenitrogenation and hydrogenation using a model oil containing dibenzothiophene, indole and naphthalene in n-heptane solution. The best catalyst was the FSP-produced material containing 16wt.% Mo (atomic ratio Co/Mo=1/3), which did not contain crystalline MoO₃ and only small amounts of CoAl₂O₄. The hydrotreating activity was approximately 75% of that of commercial cobalt molybdenum catalysts prepared by wet impregnation of pre-shaped alumina extrudates. Since the commercial catalyst is the product of years of development, this shows the potential of the flame spray pyrolysis technique.The Co–Mo–S phase, active for hydrotreating, is formed upon sulfidation of the flame made oxide precursor. TEM images of the spent catalysts showed that as the metal loading was increased from 8 to 32wt.% Mo the average length of supported MoS₂ entities increased from 3 to 4nm (for the unsupported catalyst it was 8.5nm), while the average number of MoS₂ layers per particle increased from 1.1 to 2.5. The increase in MoS₂ particle size resulted in lower activity.

Keywords: Flame spray pyrolysis; Cobalt; Molybdenum sulfide; Hydrotreating; Nanomaterial; Catalysis

Kinetic modelling of the SO₂-oxidation with Pt in a microstructured reactor by W. Benzinger; A. Wenka; R. Dittmeyer (pp. 209-217).

Display Omitted► SO₂ oxidation experiments in a microstructured test reactor. ► Numerical simulations were performed for a single channel configuration. ► For the surface chemistry a kinetic model based on elementary steps was developed. ► The assumed multi-step mechanism involves coordination of SO₂ on two surface sites. ► Model predictions and the experimental results are in good agreement.In terms of tons per day SO₃ is one of the most important chemicals in the world. It is produced via the contact process in a gas phase catalytic oxidation reaction. The contact process consists of multiple catalyst beds, inter-stage cooling and an absorption step in the case of sulphuric acid production. Transferring this process to a microstructured reactor with its unique heat and mass transport properties should make it possible to develop a small scale one pass synthesis well suited for on-site SO₃ production, e.g., for surfactant making. In a test reactor experiments were performed with different molar ratios of sulphur dioxide to oxygen, hydrodynamic residence time and reaction temperature. Numerical simulations with ANSYS FLUENT 12.0 were performed for a single channel configuration. For this purpose a detailed model of the flow, the heat distribution and the surface chemistry was used. For the surface chemistry a detailed kinetic model based on elementary steps occurring on the catalyst surface was used. The assumed multi-step mechanism involves coordination of SO₂ on two surface sites. The simulations are compared to the experimental results. Good agreement between the model predictions and the experimental results is achieved. A sensitivity analysis was performed to get an idea of the rate determining steps.

Keywords: Micro process engineering; Microstructure reactor; SO; ₂; oxidation; Platinum; Multi-step mechanism; Computational fluid dynamics

Methyl mercaptan and carbonyl sulfide traces removal through adsorption and catalysis on zeolites and layered double hydroxides by Andrey Ryzhikov; Vasile Hulea; Didier Tichit; Catherine Leroi; Didier Anglerot; Bernard Coq; Philippe Trens (pp. 218-224).

Display Omitted► Zeolites and LDH used as sorbents for methyl mercaptan and carbonyl sulfide. ► Affinity of COS is lower for Me-zeolite in comparison with CH₃SH. ► Basicity of catalysts rules the catalytic hydrolysis of COS.In this paper, the adsorption of methyl mercaptan and carbonyl sulfide by metal exchanged zeolites and layered double hydroxides (LDH) is studied. The affinity of CH₃SH for metal-exchanged zeolites was found to increase with the basicity and the valence of the cation. Yoon–Nelson modelling gave good predictions of half time of breakthrough for each zeolite tested. Thermogravimetry was used in the case of the system CH₃SH/NaX for elucidating the desorption process of CH₃SH from NaX. In contrast, the affinity of COS was found clearly lower for Me-zeolite in comparison with CH₃SH. Catalytic hydrolysis of COS was tested with the same metal exchanged zeolites and LDH materials and the basicity of the catalysts was found to strongly influence the hydrolysis.

Keywords: Methyl mercaptan; Carbonyl sulfide; Zeolites; Layered double Hydroxides; Adsorption; Hydrolysis

Influence of the surface chemistry of activated carbons on the ATRP catalysis of methyl methacrylate polymerization by S. Barrientos-Ramírez; G. Montes de Oca-Ramírez; E.V. Ramos-Fernández; A. Sepúlveda-Escribano; M.M. Pastor-Blas; A. González-Montiel; F. Rodríguez-Reinoso (pp. 225-233).

Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate (MMA) using a CuBr–[1,1,4,7,10,10-hexamethyltriethylenetetramine] (Cu^IBr/HMTETA) catalyst (Cat) supported on activated carbon.Display Omitted► Carbon is a suitable support of CuBr/HMTETA for ATRP polymerization of MMA. ► Carboxylic groups on the surface provide high polymerization control. ► Lack of surface functionalization is detrimental for the catalytic behavior.A parent activated carbon (C-0) was subjected to four different treatments: (i) heat treatment at 1273K in Ar (C-1); (ii) heat treatment at 473K in air (C-2); (iii) oxidation with H₂O₂ (C-3) and, (iv) oxidation with HNO₃ (C-4). These materials were evaluated as supports of CuBr–[1,1,4,7,10,10-hexamethyltriethylenetetramine] (Cu^IBr–HMTETA), a catalyst for the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate (MMA) using methyl-α-bromophenylacetate (MBP) as radical initiator. The supported catalysts showed an adequate control of polymerization, evidenced by polydispersity indexes (PDI) falling in the range 1.13–1.55. The best performance was achieved when activated carbon was treated with nitric acid (C-4) and with air at 473K (C-2). Some copper leaching was always detected. The catalysts were reused and an adequate polymerization control was obtained in subsequent runs.

Keywords: ATRP; Activated carbon; Surface chemistry; Catalyst; PMMA; Controlled polymerization

NO removal by activated carbon-supported copper catalysts prepared by impregnation, polyol, and microwave heated polyol processes by Kui-Hao Chuang; Chi-Yuan Lu; Ming-Yen Wey; Ya-Ni Huang (pp. 234-240).

Display Omitted► Pretreatment of AC support with HNO₃ increased the number of carboxyl sites. ► The active phases of Cu/AC prepared by the MP were Cu, CuO, and Cu₂O. ► The MP is an easy and effective preparation method for Cu/AC catalyst for NO removal.The effect of HNO₃ pretreatment of activated carbon (AC)-supported copper catalysts for NO removal with NH₃ was studied. In addition, the effects of various preparation methods for Cu/AC catalysts, namely, impregnation (IM), polyol process (P), and microwave heated polyol process (MP), on the activity of NO removal with NH₃ were compared. HNO₃ pretreatment increased the number of carboxyl sites and promoted good dispersion of active sites. In addition, the chemical states of active phases were found to be affected when the catalysts were prepared by the microwave heated polyol process. More Cu₂O particles were observed on the Cu/AC-N-MP catalyst than on the Cu/AC-N-P catalyst. The experimental results indicated that HNO₃ pretreatment of the AC support led to increased catalytic activity for NO removal with NH₃. The catalytic activity of the Cu/AC catalysts for NO removal at 200°C decreased in the following order: Cu/AC-N-MP>Cu/AC-N-P>Cu/AC-N-IM. The microwave heated polyol process is a facile method for the rapid synthesis of carbon-supported Cu catalysts for NO removal at low temperature.

Keywords: NO removal; Microwave heated polyol process; Copper species; Catalyst

Influence of the triblock copolymer P123 and phosphorous on the physico-chemical properties of TiO₂ by Vojka Žunič; Srečo D. Škapin; Marjeta Maček-Kržmanc; Ines Bračko; Andrijana Sever Škapin; Danilo Suvorov (pp. 241-249).

Display Omitted▶ Combination of sol–gel and solvothermal synthesis of TiO₂ nano-powders. ▶ TiO₂ nano-powders characterized with a high specific surface area (up to 335m²/g). ▶ Addition of phosphorous (P) inhibits particles growth during the thermal treatment. ▶ Addition of P stabilizes the anatase phase to higher annealing temperatures. ▶ The highest photocatalytic activity was obtained with pure TiO₂ anatase.Nanocrystalline TiO₂ powders with a high specific surface area (up to 335m²/g) were synthesized by a combination of sol–gel and solvothermal syntheses. The influence of the TiO₂ framework template, the triblock copolymer P123, and the framework stabilizer, phosphorous (P) in the form of phosphoric acid (H₃PO₄), on the photocatalytic oxidation of isopropanol was studied. As-prepared samples were characterized by means of X-ray powder diffraction (XRD), thermogravimetric analysis (TG-DTA), measurements of the specific surface area ( s_BET), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The photocatalytic activity under UV (ultraviolet) irradiation of the as-prepared samples was measured by monitoring the degradation of the isopropanol in the gaseous medium. The application of P123 increased the specific surface area of the samples; furthermore, the addition of phosphorous inhibited the particle growth during the thermal treatment and stabilized the anatase crystal phase at higher annealing temperatures (up to 900°C), thus leading to a higher photocatalytic activity. However, when P123 and phosphorous were used together the specific surface area was increased and an improvement in the photocatalytic oxidation was observed.

Keywords: Titanium dioxide; Nano-powder; Sol–gel synthesis; Solvothermal synthesis; Isopropanol photocatalytic oxidation

Immobilization of 1,5,7-triazabicyclo [4.4.0] dec-5-ene over mesoporous materials: An efficient catalyst for Michael-addition reactions under solvent-free condition by Pranjal Kalita; Rajiv Kumar (pp. 250-258).

Immobilization of 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD, a bicylic guanidine base) over mesoporous material like SBA-15 has been found to be an excellent catalyst for Michael-addition of β-nitro styrene with malonate. The reactions were performed under solvent-free condition at 373K for 9h. A wide variety of Michael donors and acceptors were investigated. Among them, high yield of Michael product was obtained for the reaction between p-Cl-nitrostyrene with dimethyl malonate.

Keywords: Mesoporous materials; 1,5,7-triazabicyclo [4.4.0] dec-5-ene; Michael-addition; β-nitro styrene and malonate

Solid acid catalyzed glucose conversion to ethyl levulinate by Lincai Peng; Lu Lin; Junhua Zhang; Jianbin Shi; Shijie Liu (pp. 259-265).

Display Omitted► SO₄²⁻/ZrO₂ is found to be efficient in the conversion of glucose to ethyl levulinate. ► A maximum ethyl levulinate formation yield of ca. 30mol% was obtained from glucose. ► SO₄²⁻/ZrO₂–Al₂O₃ can suppress the formation of ethyl levulinate from ethyl glucoside. ► The effect of small amounts of water present in ethanol is thought to be negligible. ► SO₄²⁻/ZrO₂ after calcination can be reused multiple times with similar product yield.A series of solid acid catalysts including SO₄²⁻/ZrO₂, SO₄²⁻/TiO₂, SO₄²⁻/ZrO₂–TiO₂ and SO₄²⁻/ZrO₂–Al₂O₃ were prepared by precipitation and impregnation method for ethyl levulinate production from glucose in ethanol. Effects of various reaction parameters and catalyst reuse cycle towards the reaction performance were studied. Experimental results showed that different components of the sulfated metal oxides had markedly different catalytic effects on the ethanolysis of glucose. SO₄²⁻/ZrO₂–Al₂O₃ could significantly suppress the formation of ethyl levulinate due to the incorporation of Al₂O₃. With SO₄²⁻/ZrO₂ as the catalyst, an optimized ethyl levulinate yield of above 30mol% was obtained at 200°C for 3h with catalyst dosage of 2.5wt%, and the recovered catalyst after calcination was found to remain active with an almost unchanged product yield after being reused five times. The main liquid substances including ethyl levulinate, diethyl ether and ethanol can be easily separated from the resulting product mixture by fractionation and the excess ethanol was recycled. The physicochemical properties of the prepared and thermally regenerated catalysts were characterized using BET surface area, XRD, NH₃-TPD and XPS techniques.

Keywords: Glucose; Ethanol; Ethyl levulinate; Solid acid catalyst

A thermodynamic study of the redox properties of supported Co particles by Kevin Bakhmutsky; Noah L. Wieder; Thomas Baldassare; Michael A. Smith; Raymond J. Gorte (pp. 266-271).

Display Omitted► Redox properties of Co catalysts were studied to understand deactivation during FTS. ► Thermodynamic properties of particles on 2-wt% Co/SBA-15 were similar to bulk Co. ► Results for low loading Co/ZrO₂ catalysts suggest interactions between CoO_x and ZrO₂. ► Pd promoters are able to break up interactions between Co and ZrO₂.The redox properties of various Co catalysts were investigated in order to understand a deactivation process that has been reported for small Co particles in Fischer–Tropsch synthesis (FTS). Coulometric titration was used to measure the equilibrium isotherms for a series of Co catalysts, including bulk CoO_x, 2-wt% Co on SBA-15, and several zirconia-supported Co (2- to 20-wt% Co) catalysts. TEM results demonstrate that the 2-wt% Co/SBA-15 consisted of particles that were less than 5nm in diameter; but the thermodynamic properties were indistinguishable from that found for bulk Co, showing that the redox properties are not a function of particle size alone. For zirconia-supported samples with 2-wt% and 5-wt% Co, about half of the Co exhibited a significant shift to lower P(O₂) for the equilibrium state associated with the coexistence of CoO and Co, implying that interactions between CoO_x and zirconia can affect the redox properties of Co and suggesting that a large fraction of the Co in these catalysts would be in the form of CoO on these samples under FTS conditions. With higher Co loadings, the equilibrium data was identical to that for bulk CoO_x. For the 5-wt% Co/zirconia catalyst, the addition of 0.5-wt% Pd shifted the equilibrium back to that found with bulk CoO_x, implying that Pd promoters are able to break up interactions between Co and zirconia.

Keywords: Cobalt; Fischer–Tropsch synthesis; Mesoporous silica; Nanoparticles; Redox thermodynamics; Reducibility; Zirconia

Spatially resolved temperature and gas species concentration changes during C₃H₆ oxidation over a Pt/Al₂O₃ catalyst following sulfur exposure by April Russell; Cary Henry; Neal W. Currier; Aleksey Yezerets; William S. Epling (pp. 272-284).

Display Omitted► Catalyst exposure to sulfur shifted C₃H₆ oxidation light-off downstream. ► Reaction front propagation through the catalyst slowed in zones exposed to sulfur. ► Partial removal of sulfur from the zones re-established activity.Spatially resolved capillary inlet mass spectrometry (SpaciMS) and infra-red thermography have been used to characterize propylene oxidation along a Pt/Al₂O₃ monolith-supported catalyst, before and after heterogeneous sulfur deposition. The combined techniques clearly illustrate reaction location, and therefore catalyst use, and how these performance indicators change following different degrees of sulfur damage, as well as after partial desulfation. With each sulfation step, light-off temperatures (T50) increased and the time for back-to-front ignition changed pattern during temperature programmed oxidation. With 1500ppm propylene fed, the reaction zones established during constant inlet temperature operation shifted further into the catalyst and increased in width following sulfur treatment. When the temperature was sufficient to achieve light-off of 4500ppm propylene, back-to-front ignition proceeded toward the inlet, such that even after sulfur deposition the reaction zones were very close to the catalyst inlet and virtually indistinguishable between catalyst sulfation states. However, IRT measurements demonstrate that the reaction light-off position did move downstream in the catalyst with sulfur damage.

Keywords: Diesel oxidation catalyst; Spatially resolved reactions; Sulfur poisoning; Propylene oxidation

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Applied Catalysis A, General (v.397, #1-2)

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Applied Catalysis A, General (v.397, #1-2)