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Applied Catalysis A, General (v.309, #1)

Editorial Board (pp. co2).

Effect of hydrogen pressure on intentional deactivation of unsupported Pt catalyst: Catalytic properties and physical characterization by Z. Paál; A. Wootsch; I. Bakos; S. Szabó; H. Sauer; U. Wild; R. Schlögl (pp. 1-9).

Unsupported Pt black reduced by hydrazine looked like an agglomeration of elongated Pt particles, as confirmed by electron microscopy. Cyclic voltammetry indicated the presence of low Miller-index (e.g. {100} and {111} facets) as well as terrace structures. This Pt catalyst was subjected to deactivating treatments with hexane (nH) alone and in the presence of H₂ of various pressures in two sets of experiments, both carried out at 483 and 603K. One series monitored catalytic reactions during deactivation and in subsequent standard test runs. The other series applied deactivating treatments quasi in situ in the electron spectrometer and were followed by XPS and UPS studies. More hydrogen favored the formation of C₆ saturated products: isomers and methylcyclopentane (MCP). XPS detected more carbon deposited in the absence of hydrogen, and accordingly the residual activity was much less after these pretreatments, being about twice as high when the pretreatment was carried out at 483K as opposed to 603K. With the same p(H₂) present in the carbonizing mixture, less C remained at 483K. The amount of retained carbon increased up to 36%. Its amount showed correlation with the activities measured in standard test runs after deactivating exposures. An abrupt increase of the activity loss appeared upon exposures at higher temperatures and with less hydrogen, resulting in 22–30%C. This was concomitant with the change of the chemical state of C: with more C, more “graphite-like�? carbon and C_xH_y polymers. “Disordered C�? or “Pt-C�? entities, poisoning active Pt ensembles may have been responsible for selectivity shift. Multilayer deposits may have appeared with more than 30%C, causing severe activity loss. Deactivation by carbon must have geometric rather than electronic reasons.

Keywords: Pt; Platinum black; Deactivation; Hexane; Hydrogen effect; Carbonaceous deposits; XPS; UPS; Cyclic voltammetry

Effect of additives on properties of V₂O₅/SiO₂ and V₂O₅/MgO catalysts by A. Klisińska; K. Samson; I. Gressel; B. Grzybowska (pp. 10-16).

Oxidative dehydrogenation, ODH of propane and ethane was studied on VO_x/SiO₂ (VSi) and VO_x/MgO (VMg) catalysts of the same vanadium loading (1.5 theoretical monolayer of vanadia) and doped with additives of main group elements (K and P) and of transition metal ions (Ni, Cr, Nb, and Mo). The additives modify both the specific activity and selectivity to olefins, the modifying effect (its sign and extent) depending on the type of the catalyst and on the alkane nature. The main difference between the two series of the catalysts consist in: (a) increase in the specific activity in the ODH reactions on introduction of the additives (except K) for VSi and decrease for VMg catalysts, (b) considerable increase in the selectivity to propene in ODH of propane for K-doped VSi catalyst and decrease for K-doped VMg catalyst (Ni, Cr, and Mo increasing and P decreasing the selectivity for the both series), and (c) higher selectivities to ethene as compared with those to propene for VSi and lower to ethene than to propene for VMg catalysts. In contrast to the propane ODH the additives exert only very small effect on the selectivities to ethene in the ODH of ethane.

Keywords: Vanadia catalysts; Additives; Oxidative dehydrogenation of propane and ethane

Effect of additives on properties of V₂O₅/SiO₂ and V₂O₅/MgO catalysts by A. Klisińska; S. Loridant; B. Grzybowska; J. Stoch; I. Gressel (pp. 17-27).

Effect of additives (A) of main group elements (P and K) and of transition metal ions (Ni, Cr, Nb and Mo) introduced to VO_x/SiO₂ (VSiA) and VO_x/MgO (VMgA) catalysts on their structure and physicochemical properties, has been studied with the use of XRD, XPS, Raman spectroscopy, H₂-TPR and TPD of adsorbed propane. Acido-basic properties were determined from IR spectra of adsorbed pyridine and from isopropanol decomposition. The results of the characterization have been correlated with catalytic data for oxidative dehydrogenation (ODH) of propane and ethane reported in Part I. The additives do not affect markedly the catalysts’ structure, but modify their acido-basic properties and reducibility. For both VSi and VMg catalysts number of acidic sites increases with the electronegativity of the additive. For VSiA catalysts, in which V₂O₅ is the main phase and acidic properties dominate over dehydrogenating, the selectivity to propene increases with the decrease in acidity and with the increase in the MO bond energy. For VMgA catalysts, containing magnesium orthovanadate, in which dehydrogenating properties dominate over acidic ones, the selectivity to propene does not depend clearly on the acido-basic properties, but appears to be influenced by the properties of the catalysts’ oxygen. Selectivity to ethene in ODH of ethane does not depend on acidic properties for both series of the catalysts.

Keywords: Vanadia-silica; Vanadia-magnesia catalysts; Additives; Oxidative dehydrogenation of propane and ethane

Pd-promoted Cr/ZnO catalyst for synthesis of methanol from syngas by Qianwen Zhang; Xiaohong Li; Kaoru Fujimoto (pp. 28-32).

The effect of palladium on the performance of Cr/ZnO catalyst was investigated for the synthesis of methanol from synthesis gas. Hydrogen adsorption on the Pd-Cr/ZnO well fits the equation combination of Langmuir isotherm equation and Freundilich isotherm equation while CO adsorption well fits Freundilich model. Addition of palladium in Cr/ZnO promoted the activity and selectivity of methanol synthesis.

Keywords: Methanol synthesis; H; ₂; adsorption; CO adsorption; Palladium; Cr/ZnO

FT-IR study of methanol, formaldehyde and methyl formate adsorption on the surface of Mo/Sn oxide catalyst by V. Lochař (pp. 33-36).

The FT-IR spectra of the surface species arising from the adsorption of methanol, formaldehyde and methyl formate on mixed molybdenum-stannic oxide with Mo/(Mo+Sn)=0.1 are discussed. Methanol is adsorbed mainly in the undissociated form due to hydrogen bond on a cation–anion couple with basic character. Methoxy complex is oxidized to a bidendate formate near 473K. Hydrogen-bonded H₂CO, coordinatively bonded H₂CO, bidendate formate and polymer species are observed during the adsorption of formaldehyde at pressure 1.5kPa. Methyl formate is adsorbed in the form of hydrogen-bonded HCOOCH₃, HCOOCH₃ coordinatively bonded, methoxy complex and bidentate formate. In contrast to MoO₃–SnO₂ catalyst with molar ratio Mo/(Mo+Sn)=0.3, formates are more stable up to 473K. This can be explained by the contribution of Sn ions during their interaction with CH₃OH, H₂CO and HCOOCH₃.

Keywords: FT-IR spectroscopy; Adsorption forms; Methanol; Stannic; Molybdenum

Influence of pretreatment conditions on low-temperature carbon monoxide oxidation over CeO₂/Co₃O₄ catalysts by Chih-Wei Tang; Chao-Chieh Kuo; Ming-Chih Kuo; Chen-Bin Wang; Shu-Hua Chien (pp. 37-43).

The modification of ceria (CeO₂) on high surface area cobaltic oxide (Co₃O₄) and the promotion effect of CO oxidation via different pretreatment conditions were studied. The high-valence cobalt oxide was prepared first by precipitation-oxidation in ice bath, followed by reduction at 230°C to get pure and high surface area cobaltic oxide (assigned as R230, S_BET=100m²g⁻¹). Further, the Ce20/R230 catalyst was prepared by impregnation with cerium nitrate (20% cerium loading). Pretreatment of Ce20/R230 catalyst was divided into two methods: reduction (under 200 and 400°C) and calcination (under 350 and 550°C). The catalysts were characterized by X-ray diffraction (XRD), infrared (IR), and diffuse reflectance spectroscopy (DRS), and temperature-programmed reduction (TPR) and by nitrogen adsorption at −196°C. The results showed that pretreatment under low-temperatures obtained both larger surface area and better activity. The Ce20/R230-H200 catalyst exhibited the highest surface area ( S_BET=109m²g⁻¹) and the best catalytic activity in CO oxidation with T₅₀ (50% conversion) at 88°C among series of catalysts due to the combined effect of cobaltic oxide and ceria. The optimized pretreatment of CeO₂/Co₃O₄ catalysts can clearly enhance the catalytic activity.

Keywords: Cobaltic oxide; Ceria; CO oxidation

One-pot synthesis of dihydropyrimidinones using facile and reusable polyoxometalate catalysts for the Biginelli reaction by Razieh Fazaeli; Shahram Tangestaninejad; Hamid Aliyan; Majid Moghadam (pp. 44-51).

The efficiency of various heteropoly compounds as well-known solid acids is investigated for the three-component condensation reaction of an aldehyde with β-ketoester and urea in acetonitrile to afford the dihydropyrimidinones (DHPM). Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields and short reaction times. Furthermore, the catalyst could be easily recovered after completion of the reaction and reused without a considerable change in its activity.

Keywords: Biginelli reaction; Polyoxometalates (POMs); Homogeneous; Heterogeneous; Multicomponent reactions (MCR); Environmentally friendly processes

Cyclic voltammetry as a tool for characterization of supported VIII group metal catalysts by Anton V. Tokarev; Leonid M. Kustov; Ari Ivaska; Dmitry Yu. Murzin (pp. 52-61).

Possibility of the cyclic voltammetry (CV) in characterization of supported VIII group metal catalysts was studied. The emphasis was laid on Pd catalysts. A standard procedure for CV measurements was proposed and validated. Reasons causing cumbersome behavior of copper underpotential deposition (UPD) were revealed. The relative surface areas of metal catalysts on conductive and non-conductive supports were measured.

Keywords: Cyclic voltammetry; Supported catalysts; Characterization; Surface area determination; Conductive and non-conductive supports

Studies on the structural change of a reaction-controlled phase-transfer [π-C₅H₅NC₁₆H₃₃]₃{PO₄[WO₃]₄} catalyst during the selective oxidation of cyclopentene to glutaric acid with aqueous H₂O₂ by Hui Chen; Wei-Lin Dai; Xin-Li Yang; Ruihua Gao; Yong Cao; Hexing Li; Kangnian Fan (pp. 62-69).

The selective oxidation of cyclopentene to glutaric acid (GAC) with aqueous hydrogen peroxide was carried out over a reaction-controlled phase-transfer catalyst—[π-C₅H₅NC₁₆H₃₃]₃{PO₄[WO₃]₄}. The high GAC yield of 83.1% was obtained on the fresh catalyst, while a much higher GAC yield of 98.8% was obtained over the recovered catalyst. The fresh catalyst, the one under reaction conditions and the recovered ones were all characterized by TG, FT-IR, Raman and³¹P NMR spectroscopy. It is interesting to find that the atomic content of tungsten and phosphorous as well as the molecular structure of the fresh catalyst all change after the reaction.³¹P NMR results reveal that under the treatment with high concentration hydrogen peroxide the insoluble catalyst can degrade into smaller and active species, which is soluble in the reaction mixture and can transfer oxygen to the CC bond, resulting in the selective cleavage of cyclopentene to glutaric acid. After the complete consumption of hydrogen peroxide, the smaller and active tungsten species will polymerize into (PW₁₁O₃₉)⁷⁻ and (PW₁₂O₄₀)³⁻ with stable Keggin structure by forming WO_cW (edge-sharing) bond. These compounds are insoluble and will precipitate from the reaction mixture after the reaction when hydrogen peroxide is used up, making it much convenient for recovering and reusing.

Keywords: Cyclopentene; Glutaric acid; Selective oxidation; Hydrogen peroxide; Reaction-controlled phase-transfer catalyst

Vapor-phase synthesis of 1,2-dihydro-2,2,4-trimethylquinolines from anilines and acetone over group 5–7 metal halide clusters as catalysts by Satoshi Kamiguchi; Ikuko Takahashi; Hideki Kurokawa; Hiroshi Miura; Teiji Chihara (pp. 70-75).

Reaction of aniline with acetone to form 1,2-dihydro-2,2,4-trimethylquinoline (1) was studied in a gas-phase reaction over halide clusters as solid acid catalysts. After activation of a niobium halide cluster, [(Nb₆Cl₁₂)Cl₂(H₂O)₄]·4H₂O (2), which has an octahedral metal framework, at an elevated temperature in a hydrogen stream for 1h, reaction was initiated by introduction of stoichiometric amounts of aniline and acetone at the activation temperature. The catalysis to yield1 became evident above 200°C. Both the catalytic activity of2 and the selectivity for1 increased with increasing temperature, having a local maximum at 300°C. The selectivity for1 was 76% with 34% conversion at 450°C. Reactions of o-, m-, and p-toluidines with acetone also produced the corresponding quinolines. The chloride clusters of tantalum with the same metal framework and rhenium with a triangular metal framework also catalyzed the condensation. Thus, a halide cluster can be a substitute for liquid acid, particularly at high temperatures.

Keywords: Halide cluster; Quinoline synthesis; Solid acid; Vapor-phase synthesis; Skraup synthesis

K₄Ce₂M₁₀O₃₀ (M=Ta, Nb) as visible light-driven photocatalysts for hydrogen evolution from water decomposition by Mengkui Tian; Wenfeng Shangguan; Jian Yuan; Li Jiang; Mingxia Chen; Jianwei Shi; Ziyuan Ouyang; Shijie Wang (pp. 76-84).

A series of single-phase metal oxide photocatalysts K₄Ce₂M₁₀O₃₀ (M=Ta, Nb), capable of evolving H₂ and O₂ from aqueous solutions containing a sacrificial electron donor (Na₂SO₃) and acceptor (AgNO₃), respectively, under visible light irradiation ( λ>420nm) without any co-catalyst were presented. The activities were greatly enhanced by the incorporation of Pt, RuO₂ and NiO (NiO_x) as co-catalysts on the prepared oxides. The photocatalysts have an appropriate band gap energy ca. 1.8–2.3eV (corresponding to absorption edge of 540–690nm) and excellent chemical potential level for utilization of solar energy, representing candidates of photocatalysts for hydrogen evolution from water decomposition. Density function theory (DFT) calculation indicated that while their valence bands are composed of hybridization with O 2p+Ta 5d (or Nb 4d) and occupied Ce 4f orbitals, the conduction bands of these photocatalysts K₄Ce₂M₁₀O₃₀ (M=Ta, Nb) are mainly attributable to the Ta 5d (or Nb 4d) orbitals. Although the unoccupied Ce 4f orbitals have overlap in the bottom of conduction band, they are less effective in transferring electrons and photocatalytic activities for their high localized nature. The contribution of these orbitals to the energy bands affects the electronic structure of the both photocatalysts and gives rise to their differences in light absorption and photocatalytic activities.

Keywords: Photocatalyst; Visible light-driven; K; ₄; Ce; ₂; M; ₁₀; O; ₃₀; (M; =; Ta, Nb); Water decomposition; DFT calculation

Synthesis of dialkyl peroxides in the presence of polymer-supported phase-transfer catalysts by Stefan Baj; Agnieszka Siewniak; Beata Socha (pp. 85-90).

The synthesis of dialkyl peroxides from alkyl hydroperoxides and alkyl bromides in the presence of polymer-supported phase-transfer catalysts has been investigated. It was revealed that polymer-bound quaternary ammonium and polyethylene glycol catalysts were more active than their soluble forms. High yields (60–92%) of the products were obtained. The catalyst could be recycled several times with no appreciable loss of activity.

Keywords: Dialkyl peroxides; Hydroperoxides; Polymer-supported phase-transfer catalysts; Triphase catalysis

Syntheses of Ti- and Al-containing hexagonal mesoporous silicas for gas-phase epoxidation of propylene by molecular oxygen by Yanyong Liu; Kazuhisa Murata; Megumu Inaba; Naoki Mimura (pp. 91-105).

Ti- and Al-containing hexagonal mesoporous silicas (Ti-Al-HMS) were synthesized through a sol–gel reaction using dodecylamine as a surfactant. All Ti⁴⁺ ions could enter into the HMS framework until Ti/Si=4mol% and all Al³⁺ ions could enter into the HMS framework until Al/Si=1mol% in Ti-Al-HMS after calcination at 923K for 4h. The Al³⁺ ions at the extra-framework of HMS are much stronger acidic sites than the Al³⁺ ions in the intra-framework of HMS. In a fixed-bed catalytic system, Ti-Al-HMS (Ti/Al/Si=4/1/100 (molar ratio)) showed 47.8% of propylene conversion and 30.6% of selectivity for propylene oxide (PO) for the propylene epoxidation by molecular oxygen at 523K. The simultaneous existence of Ti and Al in the framework of HMS is very important for improving the PO yield. An epoxide-like intermediate formed from Ti site, Al site and adsorbed O₂ was proposed for explaining the synergy effect of Ti and Al in Ti-Al-HMS for the propylene epoxidation by molecular oxygen. The Ti⁴⁺ ions at the extra-framework had little effect on improving the PO yield, and the Al³⁺ ions at the extra-framework greatly decreased the selectivity for PO, because their strong acidity promoted the oligomerization-cracking of propylene. The sol–gel method is more effective than the impregnation method for preparing a catalyst containing Ti and Al for the propylene epoxidation by molecular oxygen. Ti-Al-HMS deactivated rapidly for the propylene epoxidation at 523K due to the carbonaceous deposits on the catalyst surface. The deactivated catalyst could be regenerated by calcinating in air at 923K for removing the carbonaceous deposits. Adding a little amount of hydrogen in the feed gas obviously decreased the speed of catalyst deactivation but could not completely suppress the catalyst deactivation. The amounts of the carbonaceous deposits were 2.6wt% without H₂ and 0.9wt% with H₂ in the feed gases over Ti-Al-HMS after 3h on stream at 523K. The KNO₃ additive could improve the selectivity for PO and the Ca(NO₃)₂ additive could improve the propylene conversion over Ti-Al-HMS for the propylene epoxidation by molecular oxygen.

Keywords: Propylene; Epoxidation; Molecular oxygen; Ti-Al-HMS; Carbonaceous deposits; Metal nitrate additive

Liquid phase alkylation of phenol with 1-octene over large pore zeolites by Smita Wagholikar; S. Mayadevi; S. Sivasanker (pp. 106-114).

A comparative study is presented of the liquid phase alkylation of phenol with 1-octene over different zeolite catalysts: H-beta (BEA(15)), H-mordenite (MOR(11)) and H-USY (FAU(15)). A wide spectrum of monoalkylated products, identified as isomers of phenyl octyl ether ( O-alkylate) and octyl phenol ( C-alkylate), was formed in the reaction. The reaction was studied in detail over BEA(15), such studies included the influence of process variables such as temperature, reactant mole ratio, catalyst amount and alkali metal (K) poisoning on its performance in the alkylation reaction. A kinetic analysis of the reaction over BEA(15) was also carried out assuming a second order parallel reaction mechanism. The activity of the different catalysts for the reaction followed the order: BEA(15)>FAU(15)>MOR(11). The poisoning of BEA(15) with potassium resulted in a decrease in the catalyst activity concomitant with a decrease in the number of strong acid centres in the catalyst.

Keywords: Alkylation; Phenol; 1-Octene; Alkyl phenols; Zeolites

Niobia–silica aerogel mixed oxide catalysts: Effects of the niobium content, the calcination temperature and the surface hydrophilicity on the epoxidation of olefins with hydrogen peroxide by Filippo Somma; Alessio Puppinato; Giorgio Strukul (pp. 115-121).

Niobia–silica mixed oxides can be synthesized under acidic conditions and evaporated under supercritical conditions to yield meso-macroporous materials. The amount of active metal in the catalyst changes the acidity of the final material and in the epoxidation of allylic alcohols (geraniol) a high amount of niobium improves the production of glycols.Surface modification with methyl groups is possible by addition of methyltriethoxysilane without any change in the morphological properties of the final materials. The extent of methylation does not change significantly the surface area and the porosity but does change the catalytic activity of the materials in the epoxidation of the cyclooctene and geraniol. Methylation improves the activity of the catalysts and the use of the oxidant in the epoxidation of unsubstitued olefins, whereas only small differences were observed in the epoxidation of geraniol.

Keywords: Oxidation; Olefins; Hydrogen peroxide; Sol–gel; Supported Nb; ₂; O; ₅; catalysts

Aerobic oxychlorination of phenols catalyzed by copper(II) chloride by Luciano Menini; Elena V. Gusevskaya (pp. 122-128).

Oxychlorination of phenol and electron-rich phenolic compounds catalyzed by CuCl₂ under mild conditions has been developed. Chloride ions are used as halogenating agents and dioxygen as a final oxidant. The catalyst shows not only high regioselectivity for para- or ortho isomers but also a remarkable chemoselectivity for monochlorination, with no products of the oxidation of phenols being formed in detectable amounts. Non-phenolic aromatics and phenols with electron withdrawing substituents undergo no transformation at all under similar conditions. A free radical mechanism is suggested, which involves one-electron oxidation of phenol by CuCl₂ to the corresponding phenoxy radical followed by a rapid reaction of the tautomeric cyclohexadienyl radical with CuCl₂ resulting in chlorinated product and CuCl. Re-oxidation of CuCl by dioxygen completes a catalytic cycle. This simple, low cost and selective method might be applied for the synthesis of chlorophenols, which are widely used in pharmaceutical, agricultural and dye industries.

Keywords: Catalytic oxychlorination; Phenols; Dioxygen; Copper chloride

Enhanced performances of N₂O destruction in the presence of CO over the mixed metal oxide catalysts derived from hydrotalcite-type precursors by Kil Sang Chang; Hye-Jin Lee; Yong-Sung Park; Je-Wan Woo (pp. 129-138).

The catalytic destruction of N₂O in the presence of CO has been performed over a fixed bed of mixed metal oxide catalysts derived by calcination from hydrotalcite-type precursors. The hydrotalcite-type precursors were obtained by co-precipitation of cobalt, aluminum and some of the transition metal nitrates such as rhodium, palladium and cerium with the addition of the precipitants under controlled pH. The reactions were carried out under atmospheric pressure in the temperature range of 150–500°C and space velocities were set between 15,000 and 100,000/h. The presence of CO in excess of N₂O in the feed showed a positive effect on the N₂O destruction, leading to a decrease in the operation temperature with respect to direct N₂O decomposition. The N₂O destruction rates in the presence of CO were increased hundreds to thousands times than the rates in the absence of CO. The presence of NO in a small amount in the feed did not show any inhibition effect on the N₂O conversion in the presence of CO, but do show in the absence of CO. Some mechanistic aspects of the adsorption and the relevant reaction steps concerning the N₂O decomposition in the presence of CO have been suggested by using the results of experimental and analytical investigations.

Keywords: N; ₂; O decomposition; Mixed metal oxide catalyst; CO; Reducing agent; Nitric oxide; Hydrotalcite

Effect of γ-alumina content on catalytic performance of modified ZSM-5 for dehydration of crude methanol to dimethyl ether by Shin Dong Kim; Seung Chan Baek; Yun-Jo Lee; Ki-Won Jun; Myung Jun Kim; Ik Sang Yoo (pp. 139-143).

The effect of γ-alumina as a binder on the catalytic performance of Na-modified ZSM-5 was investigated by using the dehydration of methanol to dimethyl ether (DME). A series of modified ZSM-5 catalysts were prepared with/without γ-alumina and the activity of each catalyst was examined in the dehydration of crude methanol to DME using a fixed-bed reactor at the reaction pressure of 10atm and LHSV of 10h⁻¹. The surface and pore characteristics were investigated by Ar adsorption and the acid properties were studied by TPD of ammonia and FT-IR of adsorbed pyridine. Though the addition of γ-alumina lowered the activity of NaHZSM-5, it broadened the operative temperature range (OTR), thereby resulting in more stable catalysts. The ZSM-5 containing 70% of γ-alumina was found to be an efficient catalyst, exhibiting quite high activity as well as wide OTR. This beneficial effect is ascribed to the adequate dilution of the strong acid sites of ZSM-5 in the γ-alumina matrix.

Keywords: γ-Alumina; Binder; Crude methanol; Dimethyl ether; Modified ZSM-5; Operative temperature range

Chemo-, regio- and stereo-selective aerial oxidation of limonene to the endo-1,2-epoxide over Mn(Salen)-sulfonated SBA-15 by Lakshi Saikia; D. Srinivas; Paul Ratnasamy (pp. 144-154).

Mn(Salen) complexes immobilized on sulfonic acid-functionalized SBA-15 molecular sieves (SBA-15- pr-SO₃-Mn(Salen)) catalyze the Mukaiyama-type oxidation of R-(+)-limonene selectively to the 1,2-epoxide with molecular oxygen at 298K (Salen= N, N-ethylenebis(salicylidenaminato)). The endo-diastereomer is formed with a diasteromeric excess of 39.8%. This catalyst exhibited higher catalytic activity than “neat�? Mn(Salen) complexes directly supported on SBA-15 or zeolite-Y. A change in the oxidation state of Mn from +3 in the “neat�? complex to +2 when immobilized on the sulfonated surface is a probable cause for the observed enhancement of catalytic activity. A part of the Mn complexes was leached out of the solid phase during the reaction.

Keywords: Aerial oxidation of limonene; Chemo-, regio- and stereo-selective epoxidation; Catalysis by Mn(Salen) complexes; Sulfonic acid-functionalized SBA-15; Immobilized Mn Schiff base complexes; Mesoporous molecular sieves; Mukaiyama-type oxidation

Erratum to “Sensitization of photocatalytic activity of S- or N-doped TiO₂ particles by adsorbing Fe³⁺ cations�? [Appl. Catal. A: Gen. 302 (2006) 62–68] by Teruhisa Ohno; Zenta Miyamoto; Kazumoto Nishijima; Hidekazu Kanemitsu; Feng Xueyuan (pp. 155-156).

Calendar of Forthcoming Events (pp. 157-158).

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Applied Catalysis A, General (v.309, #1)