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Applied Catalysis A, General (v.302, #1)

Editorial Board (pp. co2).

Status of catalysis by gold following an AURICAT Workshop by Geoffrey C. Bond; David T. Thompson (pp. 1-4).

Gold catalysis; Gold-PGM catalysis; Mechanisms; Commercial applications

Characterization of Mo₂C–WO₂ composite catalysts for bifunctional isomerization: A new pulse method to quantify acid sites by A.-F. Lamic; C.-H. Shin; G. Dj�ga-Mariadassou; C. Potvin (pp. 5-13).

New bimetallic catalysts containing molybdenum carbide (Mo₂C) and tungsten dioxide (WO₂) with three different Mo/W ratios were synthesized by temperature programmed reaction in flow of C₂H₆/H₂ mixture and used for the bifunctional isomerization of n-heptane. They are characterized by X-ray diffraction (XRD), electron diffraction (ED), transmission electron spectroscopy (TEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), N₂ sorption, CO chemisorption and adsorption–desorption of iso-propylamine. New pulse method based on the adsorption–desorption of iso-propylamine was used to estimate the total amount of acid sites of which are differentiated the number of Lewis and Brönsted acid sites. XPS shows that only molybdenum and a limited part of tungsten are reduced while the major part of tungsten is under oxide form as WO₂. The adsorption of CO allows estimating the number of metallic sites (Mo₂C) and coke is formed during the isomerization of n-heptane on Brönsted acid sites (WO₂). A kinetic study gives that the reaction order is first for n-heptane conversion. The stabilisation of activity and high selectivity to iso-C₇ from 86 to 94% for the isomerization of n-heptane are observed after induction period of 9h. The turnover rate (TOR) is 0.1s⁻¹ at 300°C.

Keywords: Mo; ₂; C; WO; ₂; Br�nsted acid sites quantification; Bifunctional isomerization of; n; -heptane; TOR

Low temperature water-gas shift: Type and loading of metal impacts decomposition and hydrogen exchange rates of pseudo-stabilized formate over metal/ceria catalysts by Gary Jacobs; Sandrine Ricote; Burtron H. Davis (pp. 14-21).

In this investigation, a similar degree of surface shell reduction among a series of metal promoted ceria catalysts was established by diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and X-ray absorption near-edge spectroscopy (XANES) measurements. Surface formate species were generated by reaction of CO with bridging OH groups associated with the Ce³⁺ defect sites. The thermal decomposition of the pseudo-stable formates was followed in the absence of H₂O. Decomposition and exchange from H to D of the pseudo-stabilized formate was enhanced by changing the promoter from Au to Pt. Likewise, an increase was observed in both decomposition and exchange rates by increasing the promoter loading from 0.5 to 2.5wt.%. The results suggest that CH bond breaking is facilitated during this thermal decomposition (i.e., reverse decomposition to CO andOH). Therefore, since the rate limiting step of the forward formate decomposition (i.e., the WGS reaction) is strongly suggested to be associated with CH bond cleaving in the formate intermediate (based on earlier kinetic isotope effect and isotopic tracer studies), the results can explain the promotion in the WGS rates as observed by changing from Au to Pt and by increased promoter loading.

Keywords: Gold (Au); Platinum (Pt); Ceria (CeO; ₂; ); Formate; Water-gas shift; H–D exchange; DRIFTS

Preferential oxidation of carbon monoxide with iron-promoted platinum catalysts supported on metal foams by Paul Chin; Xiaolei Sun; George W. Roberts; James J. Spivey (pp. 22-31).

A series of 5wt% Pt/0.5wt% Fe/γ-Al₂O₃ catalysts supported on metal foams of different geometries were synthesized and tested for preferential oxidation of a low CO concentration in the presence of a high H₂ concentration. The catalysts were tested in a fixed bed adiabatic reactor at a total pressure of 0.2MPa (absolute) to simulate fuel processor operating pressure. The inlet temperature was varied from 80°C to 170°C, and the gas hourly space velocity ranged from 5000h⁻¹ to 45,000h⁻¹. The inlet gas composition to the reactor reproduced that of the effluent stream from the water-gas-shift reactor in a typical fuel processor: H₂ 42%, CO₂ 9%, H₂O 12%, CO 1.0%, O₂ 0.5–1.0%, and N₂ 35–35.5%.The geometry of a foam is characterized by the volume fraction of solid material (cell density) and by the number of pores per inch. The catalysts with lower cell densities generally exhibited higher CO conversions and selectivities. Under most operating conditions, the CO conversion and selectivity of the best metal foam catalysts were comparable to those of a 400 cells per square inch, ceramic straight-channel monolith with the same nominal catalyst loading. Both the reverse water-gas-shift (r-WGS) reaction and transport resistances affected the performance of these catalysts. Under adiabatic conditions, the r-WGS reaction made it impossible to achieve low outlet CO concentrations. The effects of space velocity and linear velocity were studied independently using various catalyst lengths and volumetric gas flow rates. At a constant space velocity, the CO conversion increased with higher linear velocities, suggesting a significant mass transfer resistance between the bulk gas and the catalyst surface.

Keywords: Carbon monoxide; Foam; Monolith; Platinum; Iron; Preferential oxidation; Selective oxidation; Water-gas-shift; Fuel cell

The role of Fe addition on the activity of Pd-containing catalysts in multiphase hydrodechlorination by E.V. Golubina; E.S. Lokteva; V.V. Lunin; N.S. Telegina; A.Yu. Stakheev; P. Tundo (pp. 32-41).

Multiphase hydrodechlorination of 1,4-dichlorobenzene, hexachlorobenzene and 2,4,8-trichlorodibenzofurane was studied in the presence of Pd/C and Pd-Fe/C catalysts. The effect of the addition of a second metal to Pd/C was investigated. The content (1–12wt.%) and ratio of metals were varied to determine their influence on catalytic activity, which was demonstrated to strongly depend on metal ratio in multiphase hydrodechlorination systems.Metal–metal interaction and structure of bimetallic particles were studied by magnetic measurements and TPR analysis. Bimetallic particles consisted of Pd-enriched PdFe alloy. Also Fe₂O₃ was presented on the surface of catalyst. Based on catalytic performance, magnetic measurements, and TPR, two aspects of the influence of iron addition were considered: (1) formation of Pd-enriched PdFe alloy, which resulted in an increase of catalytic activity of bimetallic catalysts in comparison with Pd/C; (2) formation of FeCl₃ under HDC reaction condition, which prevented complete chlorination of palladium, possibly leading to its deactivation.

Keywords: Hydrodechlorination; Bimetallic catalyst; Palladium; Multiphase reaction

Preyssler catalyst, [NaP₅W₃₀O₁₁₀]¹⁴⁻: A green, efficient and reusable catalyst for esterification of salicylic acid with aliphatic and benzylic alcohols by Fatemeh F. Bamoharram; Majid M. Heravi; Mina Roshani; Manochehr Jahangir; Ali Gharib (pp. 42-47).

A series of eco-friendly solid acid catalysts, including H₁₄[NaP₅W₃₀O₁₁₀], H₁₄–P₅, H₁₄[NaP₅W₂₉MoO₁₁₀], H₁₄–P₅Mo, and silica supported H₁₄[NaP₅W₃₀O₁₁₀], H₁₄–P₅/SiO₂ have been used as catalysts for esterification of salicylic acid with aliphatic alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, t-butanol, 1-pentanol, and 2-pentanol) and benzylic alcohols (benzyl, 2-methylbenzyl, 2-chlorobenzyl, 4-bromobenzyl, 3-nitrobenzyl, and 4-methoxy benzyl) alcohol.The performance of different forms of Preyssler's anion in the presence of dichloroethan as the solvent of choice was compared with H₂SO₄. In all cases, maximum of ester yields and product selectivity (100%) was observed by using H₁₄–P₅ as catalyst. The esterification reactions were extended with other aliphatic and aromatic acids.

Keywords: Preyssler; Catalyst; Heteropolyacid; Esterification; Salicylic acid; Benzylic alcohols

Catalytic performance of vanadium incorporated MCM-41 catalysts for the partial oxidation of methane to formaldehyde by Guoan Du; Sangyun Lim; Yanhui Yang; Chuan Wang; Lisa Pfefferle; Gary L. Haller (pp. 48-61).

The catalytic performance of incorporated V-MCM-41 catalysts for the partial direct oxidation of methane to formaldehyde with molecular oxygen has been investigated. V-MCM-41 catalysts containing 0.56–1.86wt.% V have been prepared by incorporating the vanadium ions into the framework of mesoporous siliceous MCM-41, resulting in a highly ordered structure with large BET surface area and high surface density of isolated vanadium atoms. The structure of the V-MCM-41 catalysts was studied by N₂ physisorption. The influence of the main reaction parameters, i.e. reaction temperature, reaction pressure, CH₄:O₂ ratio, gas hourly space velocity (GHSV) and vanadium content, on the selectivity and space time yield (STY) of formaldehyde were studied. A formaldehyde selectivity of 59.4% using a 0.56wt.% vanadium loading V-MCM-41 catalyst was achieved at a temperature of 873K, pressure of 12psi, CH₄:O₂ molar ratio of 13:1, GHSV of 2.0×10⁵lkg⁻¹h⁻¹. The highest STY_HCHO of 2103gkg⁻¹h⁻¹ with a high HCHO selectivity of 53.2% was obtained with the V-MCM-41 catalyst containing 1.86wt.% vanadium loading at 933K, CH₄:O₂ ratio of 13:1, GHSV of 1.3×10⁶lkg⁻¹h⁻¹. The improved catalytic performance of the V-MCM-41 catalysts is related to the highly dispersed vanadium oxide species forming a high concentration of isolated active sites, which are crucial to minimize the consecutive oxidation of formaldehyde to carbon oxides.

Keywords: V-MCM-41; N; ₂; physisorption; Partial oxidation of methane; Formaldehyde; Space time yield (STY)

Sensitization of photocatalytic activity of S- or N-doped TiO₂ particles by adsorbing Fe³⁺ cations by Teruhisa Ohno; Zenta Miyamoto; Kazumoto Nishijima; Hidekazu Kanemitsu; Feng Xueyuan (pp. 62-68).

A new method to dope Fe³⁺ ions only onto the surface of S- or N-doped TiO₂ is proposed. The photocatalytic activities of Fe³⁺ ions adsorbed on S- or N-doped TiO₂ photocatalysts for oxidation of 2-propanol are markedly improved compared to those of S- or N-doped TiO₂ without treatment of Fe³⁺ ions under a wide range of incident light wavelengths, including UV light and visible light. When the amount of Fe³⁺ ions adsorbed on S-doped TiO₂ particles was 0.90wt.%, photocatalytic activity reached maximum. In the case of N-doped TiO₂ with Fe³⁺ ions, the optimum amount of Fe³⁺ ions was 0.36wt.%. The photocatalytic activities of Fe³⁺ ions adsorbed on S- or N-doped TiO₂ photocatalysts decreased gradually when the amount of Fe³⁺ ions was greater than 1.0wt.%. In addition, when S- or N-doped TiO₂ photocatalysts adsorbed with Fe³⁺ ions was observed after reduction by NaBH₄ followed by air oxidation, further improvement in their photocatalytic activities were observed. In this case, the optimum amounts of Fe³⁺ adsorbed on the surfaces of S- and N-doped TiO₂ photocatalysts were 2.81 and 0.88wt.%, respectively. During the treatment, Fe³⁺ ions adsorbed on S- or N-doped TiO₂ were reduced to generate metal Fe, and Fe was reoxidized again to form Fe³⁺ ions under an aerated condition. After the treatment, the crystal structure of Fe³⁺ ions adsorbed on S-doped TiO₂ and adsorbtivity of 2-propanol on the photocatalyst were changed.

Keywords: Photocatalysts; Titanium dioxide; Visible light; S-doped TiO; ₂; N-doped TiO; ₂; Fe; ³⁺; ions; Reduction and oxidation

An effective method to enhance the stability on-stream of butene aromatization: Post-treatment of ZSM-5 by alkali solution of sodium hydroxide by Yueqin Song; Xiangxue Zhu; Yi Song; Qingxia Wang; Longya Xu (pp. 69-77).

The catalytic stability of ZSM-5 zeolite in butene aromatization was improved by the treatment of ZSM-5 zeolite with sodium hydroxide solution of appropriate concentration. By characterizing pore structures, the acidity of the catalyst and the coke amount, we found that alkali-treatment of ZSM-5 led to a formation of new mesopores resulting from a preferential removal of silicon species, while the intrinsic micropores remained unchanged. As for the acidity, the amount and properties of acid sites exhibited a slight change on the alkali-treated ZSM-5 zeolites. In addition, the alkali-treatment to ZSM-5 zeolite led to only a little reduction in the amount of coke during the butene aromatization. But a portion of coke was deposited in the newly created mesopores because of the alkali-treatment and the formation of coke in the micropores was found to be reduced. These changes can suppress the channel blockage of ZSM-5 zeolite by the coke deposits during butene aromatization. The variation of the coking location was the main reason for the favorable enhancement in the reaction stability during butene aromatization.

Keywords: Butene aromatization; Stability; ZSM-5; Alkali-treatment

A bimodal catalytic membrane having a hydrogen-permselective silica layer on a bimodal catalytic support: Preparation and application to the steam reforming of methane by Toshinori Tsuru; Hiroaki Shintani; Tomohisa Yoshioka; Masashi Asaeda (pp. 78-85).

The steam reforming of methane for hydrogen production was experimentally investigated using catalytic membrane reactors, consisting of a microporous silica top layer, for the selective permeation of hydrogen, and an α-alumina support layer, for catalytic reaction of the steam reforming of methane. An α-alumina support layer with a bimodal structure, which was proposed for the enhanced dispersion of Ni catalysts, was prepared by impregnating γ-Al₂O₃ inside α-Al₂O₃ microfiltration membranes (1μm in pore diameter), and then immersing the membranes in a nickel nitrate solution, resulting in a bimodal catalytic support. The bimodal catalytic support showed a large conversion of methane at a high space velocity compared with a conventional catalytic membrane with a monomodal structure. The enhanced activity of Ni-catalysts in bimodal catalytic supports was confirmed by hydrogen adsorption measurements. A bimodal catalytic membrane, i.e. a silica membrane coated on a bimodal catalytic support, showing an approximate selectivity of hydrogen over nitrogen of 100 with a hydrogen permeance of (0.5–1)×10⁻⁵m³m⁻²s⁻¹kPa⁻¹ was examined for the steam reforming of methane. The reaction was carried out at 500°C, and the feed and permeate pressures were maintained at 100 and 20kPa, respectively. Methane conversion could be increased up to approximately 0.7 beyond the equilibrium conversion of 0.44 by extracting hydrogen from the reaction stream to the permeate stream.

Keywords: Membrane reactor; Hydrogen; Bimodal catalytic membrane; Steam reforming of methane; Microporous silica membrane

A protocol on yields to synthesize commercial imperative bisphenols using HPA and supported HPA: Effective condensation over solid acid catalysts by Seshachalam Udayakumar; Samikannu Ajaikumar; Arumugam Pandurangan (pp. 86-95).

The most common method of bisphenol synthesis is the condensation of a ketone or aldehyde with phenol in the presence of an acidic condensing agent. Liquid-phase bisphenol synthesis from phenolic compounds using aldehydes condensation reaction has been investigated over heteropolyacid (HPA) and supported HPA catalysts, with various percentages of impregnation. These catalysts have been characterized: their phase purity was obtained with XRD, their surface area and their pore diameters were obtained with BET, and their acidity was obtained with FT-IR. The SEM and TEM pictures will show the morphology of host material and the dispersion of HPA on the silicon matrix, respectively. Surface coverage of HPA on host materials was confirmed with the FT-IR techniques. The reaction was optimized for better yields with various parameters like solvent, mole ratio and percentage of HPA present in the catalyst. The increase in the acidity to a certain level increases the acid-catalyzed condensation reaction. Though the host material does not suffer in structural distortions at HPA loadings, it leads to a considerable change in the structural order. The reaction needs those materials with optimum pore size for this condensation reaction. Hence optimum loading shows very high influence on the catalytic activity.

Keywords: HPA; HPA/Si-MCM-41; Bisphenol; Phenol; Aldehyde; Mole ratio

CO oxidation over gold-supported catalysts-coated ceramic foams prepared from stainless steel wastes by M.I. Dom�nguez; M. S�nchez; M.A. Centeno; M. Montes; J.A. Odriozola (pp. 96-103).

A multilayer replication method has been used to prepare reticulated ceramic foams from steel making wastes. These ceramic sponges have been used as support for preparing catalytic devices, after deposition of catalytic coatings of Al₂O₃, CeO₂ and gold. The obtained catalytic systems are active to the CO oxidation reaction and may be stable with no loss of activity as far as the amount of residual water in the gaseous stream remains constant. In the absence of water and reaction temperatures of 150�C the catalytic monolith shows 100% conversion of CO at least for 54h. The metal content of the wastes has a positive influence in the activity of the foams. The best catalytic results are obtained for the Au/CeO₂-supported foams where the oxidation capability of gold atoms is combined with the redox properties of the ceria phase.

Keywords: Gold catalysts; Wastes; CO oxidation; Ceramic foams

IR studies of OH groups in mesoporous aluminosilicates by K. G�ra-Marek; J. Datka (pp. 104-109).

The properties of acidic hydroxyl groups and Lewis acid sites in amorphous mesoporous aluminosilicates was followed by quantitative IR studies of ammonia adsorption and by low temperature studies of CO adsorption. We studied aluminosilicates synthesized by three methods: via atrane complexes, by grafting aluminium onto the siliceous material (HMCM-48) and in aqueous solution following a typical synthesis procedure (HMCM-41). IR spectra of OH groups showed weak but well seen band of Si–(OH)–Al groups at 3600–3610cm⁻¹. The post-synthesis grafting of Al into MCM-48 was found to be the most effective way to produce mesoporous material with large content of Brønsted acid sites. IR studies have shown that the stoichiometry of dehydroxylation of the amorphous mesoporous materials was different than for zeolites: in mesoporous materials one Brønsted site lost created one Lewis acid site. IR experiments of CO sorption evidenced that generally two kinds of Si–(OH)–Al groups exist in mesoporous aluminosilicates: weakly acidic ones of Δ ν_OH⋯CO≈160cm⁻¹ (similar to that in zeolite NaHX), present in all the materials, hydroxyls of moderate acidity of Δ ν_OH⋯CO≈200cm⁻¹ (acid strength intermediate between that in zeolites NaHX and NaHY) present in HMCM-41 and HMCM-48, or hydroxyls of high acidity of Δ ν_OH⋯CO≈300cm⁻¹ (similar to that in highly siliceous zeolite HZSM-5) present in aluminoslicate prepared via atrane complexes method. This method of synthesis was found to be the most effective in preparation of mesoporous aluminosilicates with the strongest Brønsted acid sites. The weakly acidic hydroxyls in mesoporous aluminosilicates are very prone to dehydroxylation, they are lost at as low temperature as 800K, hydroxyls of moderate, or high acidity are resistant to dehydroxylation and behave like zeolitic OH groups.

Keywords: Acidity; OH groups; Mesoporous materials; Dehydroxylation; IR spectroscopy

Gold on titania catalysts, influence of some physicochemical parameters on the activity and stability for the oxidation of carbon monoxide by Fran�ois Moreau; Geoffrey C. Bond (pp. 110-117).

In the standard deposition-precipitation method for preparing Au/TiO₂ (P-25) catalysts, after addition of NaOH to the HAuCl₄ solution and introduction of the P-25, the suspension was heated to 343K. As the pH was increased from 2 to 9, the gold uptake decreased but the specific activity rose as the particles became smaller. Excellent catalysts were however made by conducting the whole preparation at room temperature, showing that heating to 343K as was done earlier was quite unnecessary. No advantage was found in performing preparations in the dark.In a second preparation method HAuCl₄ solution was heated at 343K before TiO₂ addition. This method of preparation, if carried out at pH 6, ensured total deposition of the gold, a relatively high activity for CO oxidation, and represents the best compromise from a practical standpoint.Catalysts made with a high-area anatase (90m²g⁻¹) responded to the pH used in the preparation in a similar way as TiO₂ (P-25), but the pH for optimum activity covered a wider range (7–9). Preparations made with anatase of high surface area (240 or 350m²g⁻¹) gave complete recovery of gold from solution, but had only a low catalytic activity. Maximum specific rate was found with anatase of 37m²g⁻¹, the value being only slightly lower than the highest value given with the P-25 support.The safest way for preserving the activity of Au/TiO₂ catalysts is by keeping them below ambient temperature. The activity loss observed during long-term CO oxidation experiments could be restored by oxidation at 573K. Sintered catalysts could be reactivated by treatment with aqua regia and re-deposition of the gold precursor at pH 9.

Keywords: CO oxidation; Au/TiO; ₂; Deposition precipitation; Stability; Storage; Reactivation

Role of Pt in high performance Pt-Mo catalysts for hydrotreatment reactions by M.H. Pinz�n; A. Centeno; S.A. Giraldo (pp. 118-126).

The effect of Pt/(Pt+Mo) atomic ratio, metal content and the characteristics of the alumina support on activity and synergy in hydrotreatment (HDT) reactions were studied. Pt-Mo supported on different commercial gamma alumina (γ-Al₂O₃) catalysts with different metal contents were prepared and evaluated in simultaneous dibenzothiophene (DBT) hydrodesulfurization (HDS) and naphthalene hydrogenation (HYD) reactions. The characterization of the catalysts was performed using CO chemisorption, proton affinity distribution (PAD) and infrared (IR) spectroscopy of adsorbed NO. The Pt/(Pt+Mo) atomic ratio drastically influences the catalytic behavior. The formation of active sites with high activity and an important synergistic effect is enhanced at a very specific low metals composition of the catalysts. The characterization results suggest that the enhanced HDS and HYD activities are due to an improved dispersion of the active species on the support, which was reached at low metal contents and a specific atomic ratio. Moreover, this improved dispersion was influenced by the surface composition of the alumina and could be associated with a specific interaction between the Pt and the hydroxyl groups of the alumina as well as with the formation and distribution of the Mo active phase exposed on the support.

Keywords: Hydrodesulfurization; Hydrotreatment; Platinum-molybdenum; Proton affinity distribution; CO adsorption; NO adsorption

Gold catalysts supported on ceria and ceria–alumina for water-gas shift reaction by D. Andreeva; I. Ivanov; L. Ilieva; M.V. Abrashev (pp. 127-132).

Gold-supported catalysts on ceria and ceria–alumina with different ratios in the water-gas shift reaction were studied. It was shown that the addition of alumina leads to the deeper oxygen vacancies formation, detected by Raman and TPR measurements. It was established an increase of the ceria dispersion and as well as slightly increase of the gold particle size. In the presence of alumina after catalytic operation the dispersion of gold and ceria practically does not change. The lower WGS activity on gold/ceria–alumina can be explained on the basis of reduction–oxidation cycle of the reaction. It was established no efficiency re-oxidation of the catalyst surface at the temperatures of the reaction test by the water vapour and we consider this as a main reason of the lower catalytic activity.

Keywords: Gold; Ceria–alumina; WGS; TPR

Hydrogen production from partial oxidation of iso-octane over Ni/Ce_0.75Zr_0.25O₂ and Ni/β″-Al₂O₃ catalysts by Sitthiphong Pengpanich; Vissanu Meeyoo; Thirasak Rirksomboon; Johannes Schwank (pp. 133-139).

In this study, the partial oxidation of iso-octane over Ni/Ce_0.75Zr_0.25O₂ and Ni/β″-Al₂O₃ catalysts was investigated. The results indicated that Ni/Ce_0.75Zr_0.25O₂ is more active than Ni/β″-Al₂O₃. The partial oxidation products were mainly H₂ and CO for Ni/Ce_0.75Zr_0.25O₂ catalyst, with hydrogen selectivity up to 53% in the temperature range of 550–800°C with a C/O feed ratio of 1. The H₂/CO ratio was in the range of 1.3–1.7 depending on the operating temperature. At temperatures above 700°C, the presence of methane was detected. The main products of iso-octane partial oxidation over Ni/β″-Al₂O₃ catalyst were CO₂ and i-C₄H₈ at temperatures below 650°C while H₂ and CO along with small amount of hydrocarbons such as CH₄, C₂H₄, C₂H₆ and C₃H₆ were obtained at temperatures above 650°C, yielding a H₂/CO ratio of about 1.3. As a result, the hydrogen selectivity was lower than that of Ni/Ce_0.75Zr_0.25O₂ catalyst. For both catalysts, the carbon dioxide and carbon monoxide selectivities were decreased whilst the hydrogen and hydrocarbons selectivities were increased with increasing C/O feed ratio. The Ni/Ce_0.75Zr_0.25O₂ catalyst can be operated over a wider C/O feed ratio range than the Ni/β″-Al₂O₃ catalyst, resulting in less amount of carbon formed. The presence of steam in the feed yielded a larger amount of hydrogen and less amount of coke formation. Since the iso-octane conversion of both catalysts remained unchanged after a prolonged reaction time, a decrease in H₂ selectivity for Ni/β″-Al₂O₃ catalyst may be attributed to the phase change of β″-Al₂O₃ in the presence of steam.

Keywords: iso; -Octane; Partial oxidation; Ni/CeO; ₂; –ZrO; ₂; Ni/β″-Al; ₂; O; ₃

Synthesis of methyl isobutyl ketone from acetone over metal-doped ion exchange resin catalyst by Sandip Talwalkar; Sanjay Mahajani (pp. 140-148).

The kinetics of one-step synthesis of methyl isobutyl ketone from acetone was studied in the presence of the bifunctional commercial ion exchange resin, Amberlyst CH28 over a wide range of temperature, total pressure and catalyst loading in a batch reactor. An activity-based kinetic model is proposed to predict the observed results, with the non-idealities of the liquid phase being described using the UNIQUAC method. Formation of mesityl oxide was found to govern the overall rate of reaction. Low reaction rates were observed at higher conversion, possibly due to a pseudo-equilibrium caused by reversible deactivation of the catalyst as a result of formation of water in the reaction system. Simultaneous removal of water during the course of the reaction may result in an enhanced conversion.

Keywords: Methyl isobutyl ketone; Bifunctional catalyst; Hydrogenation; Ion exchange resin; Acetone; Mesityl oxide

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Applied Catalysis A, General (v.302, #1)