Catalysis Communications (v.8, #12)

Editorial board (pp. ifc).

contents continued from IBC (pp. iv-viii).

ZrOCl₂·8H₂O as an efficient, environmentally friendly and reusable catalyst for synthesis of benzoxazoles, benzothiazoles, benzimidazoles and oxazolo[4,5- b]pyridines under solvent-free conditions by Iraj Mohammadpoor-Baltork; Ahmad Reza Khosropour; Seyedeh Fatemeh Hojati (pp. 1865-1870).

A new and efficient method for the preparation of benzoxazoles, benzothiazoles, benzimidazoles and oxazolo[4,5- b]pyridines from reactions of orthoesters with o-substituted aminoaromatics and 2-amino-3-hydroxypyridine in the presence of catalytic amounts of the moisture stable, inexpensive ZrOCl₂·8H₂O under solvent-free conditions is presented. This new protocol has the advantages of easy availability, easy handling, stability, reusability and eco-friendly of the catalyst, high yields, very short reaction times, solvent-free reaction conditions, simple experimental and work-up procedure.

Keywords: ZrOCl; ₂; ·8H; ₂; O; Benzoxazoles; Benzothiazoles; Benzimidazoles; Oxazolo[4,5-; b; ]pyridines; Orthoesters

MCM-41 catalyzed rapid and efficient one-pot synthesis of polyhydroquinolines via the Hantzsch reaction under solvent-free conditions by Lingaiah Nagarapu; M. Dharani Kumari; N. Vijaya Kumari; Srinivas Kantevari (pp. 1871-1875).

A one-pot four-component reaction of aldehydes, 5,5-dimethyl-1,3-cyclohexanedione, ethyl acetoacetate and ammonium acetate has efficiently been carried out in the presence of 1mol% of MCM-41 as a heterogeneous catalyst in a solvent-free media at 90°C to form the corresponding polyhydroquinoline derivatives via the Hantzsch reaction. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction time (15–25min), milder conditions and the remarkable reusability of the catalyst, MCM-41.

Keywords: MCM-41; 5,5-Dimethyl-1,3-cyclohexanedione; Ethyl acetoacetate; Solvent-free media; Reusability

Sulfamic acid as an efficient and recyclable catalyst for the ring opening of epoxides with amines and anilines: An easy synthesis of β-amino alcohols under solvent-free conditions by Ahmed Kamal; B. Rajendra Prasad; A. Malla Reddy; M. Naseer A. Khan (pp. 1876-1880).

Application of sulfamic acid as an efficient and green catalyst for the ring opening of epoxides by aliphatic and aromatic amines under solvent-free conditions is described. In this process the use of basic neutralization agent was not required due to the intrinsic zwitterionic property of sulfamic acid. The salient features of this methodology are cheaper process, easy availability of the catalyst, versatility, and the catalyst can be recovered after completion of the reaction and can be recycled without affecting the catalytic property.

Keywords: Sulfamic acid; β-Amino alcohols; Amines; Epoxides; Solvent-free conditions

Microwave-assisted synthesis of MgO–CNTs supported ruthenium catalysts for ammonia synthesis by Qing-Chi Xu; Jing-Dong Lin; Jun Li; Xian-Zhu Fu; Ying Liang; Dai-Wei Liao (pp. 1881-1885).

Small and uniform ruthenium nanoparticles (1.3–2.0nm) supported on the mixture of MgO and carbon nanotubes (CNTs) were prepared by microwave irradiation and the promoted Ru/MgO–CNTs (K–Ru/MgO–CNTs-a) exhibited high activity for ammonia synthesis. The results show that the highest activity of the K–Ru/MgO–CNTs-a catalyst is5631μmolh-1g-cat-1 under 0.20MPa at 683K. The activity is 2.2 times as active as that of K–Ru/MgO–CNTs-b prepared by conventional wet impregnation process. Moreover, this method preparing K–Ru/MgO–CNTs-a catalyst is fast and simple.

Keywords: Ammonia synthesis; Ruthenium; Microwave; Carbon nanotubes; MgO

Highly efficient synthesis of coumarin derivatives in the presence of H₁₄[NaP₅W₃₀O₁₁₀] as a green and reusable catalyst by Majid M. Heravi; Marzieh Khorasani; Fatemeh Derikvand; Hossein A. Oskooie; Fatemeh F. Bamoharram (pp. 1886-1890).

A variety of heteropolyanions including: Keggin, Dawson, Preyssler, mixed addenda and sandwich types, catalyzed the formation of 4-methylnaphtho-(1,2- b)-pyran-2-one (coumarin) from the condensation of α-naphthol and ethylacetoacetate in a solvent free system and under heating conditions. Our data vividly indicate that sodium30–tungsto pentaphosphate, [NaP₅W₃₀O₁₁₀]¹⁴⁻, which so-called Preyssler’s anion, with high hydrolytic (pH 0–12) and thermal stability is the catalyst of choice. This catalyst catalyzed the synthesis of other coumarin derivatives in high yields and good selectivity.

Keywords: Coumarin; Heteropolyacid; Preyssler catalyst; Pechmann

Dehydrogenation of cyclohexanol on Cu–ZnO/SiO₂ catalysts: The role of copper species by Dinghao Ji; Wanchun Zhu; Zhenlu Wang; Guojia Wang (pp. 1891-1895).

For the dehydrogenation of cyclohexanol a series of Cu–ZnO/SiO₂ catalysts with various Cu to ZnO molar ratios was prepared using the impregnation method, with the loading of copper fixed at 9.5at.%. The catalysts were characterized by XPS, H₂–N₂O titration, BET, H₂-TPR, NH₃-TPD and XRD techniques. The results indicate that the addition of ZnO can improve the dispersion of copper species on reduced Cu–ZnO/SiO₂ (CZS) catalysts. Cu⁰ and Cu⁺ species were found on the reduced CZS catalysts surface, and the amount of Cu⁺ increased with the content of ZnO increasing. The addition of ZnO increased the acidity of the CZS catalysts. However, only Cu⁰ species can be found on the reduced Cu/SiO₂ (CS) catalyst surface. According to the reaction results, we found that the selectivity to phenol was related to the amount of Cu⁺ species, the Cu⁺ species should be the active sites for the production of phenol, the Cu⁰ is responsible for cyclohexanol dehydrogenation to cyclohexanone.

Keywords: Dehydrogenation; Cyclohexanol; Phenol; Cu; ⁺; Cu–ZnO/SiO; ₂

Effects of precursors on the surface Mn species and the activities for NO reduction over MnO_x/TiO₂ catalysts by Junhua Li; Jianjun Chen; Rui Ke; Chuankui Luo; Jiming Hao (pp. 1896-1900).

TiO₂-supported manganese oxide catalysts were prepared from two different precursors, manganese nitrate (MN) and manganese acetate (MA), and these samples were characterized by BET, XRD, TG/DTA, XPS and FT–IR. The characterization results showed that the MN precursor resulted primarily in MnO₂, accompanied with some Mn-nitrate, while the MA precursor caused mainly Mn₂O₃ species. These two different precursors also led to different surface Mn atom concentrations indicated by XPS and NH₃ adsorption. Consequently, the higher low-temperature activity of MnO_x/TiO₂ from MA precursor was attributed to higher surface Mn concentration and the surface Mn₂O₃ species.

Keywords: De-NO; _x; ,Selective catalytic reduction; Precursor; MnO; _x; /TiO; ₂; Low-temperature

Synthesis and characterization of mesoporous Mn/Al-SBA-15 and its catalytic activity for NO reduction with ammonia by Xi Liang; Junhua Li; Qichun Lin; Keqin Sun (pp. 1901-1904).

Al-SBA-15 was prepared by one-step hydrothermal synthesis method, and was characterized by X-ray diffraction, N₂-adsorption, transmission electron microscope and Fourier infrared spectra of chemisorbed pyridine (Py-IR). The results showed that Al-SBA-15 had well-ordered hexagonal mesopores. As compared with Si-SBA-15, Al-SBA-15 had thicker pore wall, higher surface area, and stronger Lewis acidity. Due to the stronger Lewis acidity, Mn/Al-SBA-15 catalyst prepared by impregnation showed better activity than Mn/Si-SBA-15 in the selective catalytic reduction of NO by NH₃.

Keywords: Al-SBA-15; One-step hydrothermal synthesis; Lewis acidity; Ammonia; SCR

A novel catalyst for gas phase hydrodechlorination of chlorobenzene: Silica supported Ni₃P by Xuguang Liu; Jixiang Chen; Jiyan Zhang (pp. 1905-1909).

The silica supported nickel and Ni₃P catalysts were used for the gas phase catalytic hydrodechlorinaton of chlorobenzene, and their properties were characterized by means of H₂ temperature programmed reduction (H₂-TPR), N₂ adsorption, X-ray diffraction (XRD), H₂ temperature programmed desorption (H₂-TPD) and X-ray photoelectron spectroscopy (XPS). Compared with the nickel catalyst, the Ni₃P catalyst showed remarkably better catalytic performance for the hydrodechlorinaton of chlorobenzene, which was mainly attributed to more spilt-over hydrogen species on its surface. The spilt-over hydrogen species was responsible for promoting the dissociation of C–Cl bonds.

Keywords: Hydrodechlorination; Chlorobenzene; Trinickel phosphide; Hydrogen spillover

Novel stereo controlled glycosylation of 1,2,3,4,6-penta- o-acetyl-β-d-glucopyranoside using MgO–ZrO₂ as an environmentally benign catalyst by Vishal Y. Joshi; Manohar R. Sawant (pp. 1910-1916).

Glycosylation reactions are most commonly encountered in nature. Synthetically, glycosylations are carried out with Lewis acid catalysts or mineral acids. However an environmental threat associated with catalysts has encouraged process modification by alternative development of solid catalysts based glycosylation reactions, which are commercially viable as well. In this contribution comparative study of glycosidic bond formation of 1,2,3,4,6-penta- o-acetyl-β-d-glucopyranoside with various alcohols over variety of reaction promoters/catalyst like p-toluene sulphonic acid, HCl, H₂SO₄ and MgO–ZrO₂ were taken up to evaluate the performance of this potential promoter/catalysts systems. The best catalyst for the selective synthesis of alkyl-β-d-glucopyranosides was MgO–ZrO₂ which remains active upto three runs. This replacement of homogeneous acid catalysts by heterogeneous base catalyst shows alkyl-β-d-glucopyranoside as major product at comparatively low temperature range. The effects of variety of parameters were studied in a batch reactor. The mechanism of the reaction over basic mixed metal oxide at 363K is put forth.

Keywords: Glycosidic bond formation; Heterogeneous base catalyst; Selective synthesis of alkyl-β-; d; -glucopyranoside

Photoremediation of natural leachate from a municipal solid waste site in a pilot-scale bubble column reactor by A.S. Qazaq; T. Hudaya; I.A.L. Lee; A. Sulidis; A.A. Adesina (pp. 1917-1922).

An 18-litre pilot-scale bubble column photoreactor has been used to carry out the mineralisation of a municipal solid waste dirty brown leachate. Rate data collected at 300K and atmospheric pressure with titania particles suspended in upward flowing oxidising air through a stationary liquid phase suggested that the mineralisation of humic compounds was accompanied by a parallel hydrolytic photodecomposition of nitrogenous matter toNH4+ ions. The total organic carbon (TOC) reduction rate followed a Langmuir–Hinshelwood kinetics, whileNH4+ ions production is competitively inhibited at high TOC concentration (>35mM). Photoremediation was also attended by significant (50–70%) decolourisation. The treated leachate may be recycled for agricultural use.

Keywords: Photoremediation; Titania; Bubble column reactor; Total organic carbon; Municipal solid waste leachate

Zirconium phosphonate immobilized chiral amino alcohol for heterogeneous enantioselective addition of diethylzinc to benzaldehyde by Botao Zheng; Xinjun Wu; Xuebing Ma; Lingshan Xiao; Yeling Ji; Xiangkai Fu (pp. 1923-1928).

The chiral (1 R,2 S)-(−)-2-amino-1,2-diphenylethanol and (1 S,2 R)-(+)-2-amino-1,2-diphenylethanol had been immobilized on the layered frame of zirconium phosphate to obtain zirconium phosphonates (1 R,2 S)-(−)-4a and (1 S,2 R)-(+)-4b. The enantioselective addition of Et₂Zn to benzaldehyde using zirconium phosphonates (1 R,2 S)-(−)-4a and (1 S,2 R)-(+)-4b as heterogeneous catalysts yielded secondary alcohol in 80.1% yield and e.e. values of up to 54.3%, which was only 7.6% e.e. lower than that using the corresponding ligands (1 R,2 S)-(−)-2a and (1 S,2 R)-(+)-2b as homogeneous catalysts. The zirconium phosphonates (1 R,2 S)-(−)-4a and (1 S,2 R)-(+)-4b were characterized by IR, SEM, XRD and TG analysis. SEM and XRD data showed that the catalysts (1 S,2 R)-(+)-4b and (1 R,2 S)-(−)-4a were in aggregate and mesopore structure with the same interlayer spacing 2.48nm and pore diameter 5.6nm.

Keywords: Immobilized; Zirconium phosphonate; Heterogeneous; Enantioselective addition

Copper(II) tetrafluoroborate as a mild and efficient catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1 H)-ones under solvent-free conditions by Ahmed Kamal; Tadiparthi Krishnaji; Mohd. Ameruddin Azhar (pp. 1929-1933).

A simple, mild and efficient procedure for the synthesis of dihydropyrimidinones using copper(II) tetrafluoroborate as a new catalyst is described under solvent-free conditions in shorter reaction times at room temperature.

Keywords: Biginelli; 3,4-Dihydropyrimidinones; Copper(II) tetrafluoroborate; Solvent-free; Bioactivity; Three-component condensation

Hydrogen storage characteristics of metal oxide doped Al–MCM-41 mesoporous materials by Savidha Ramachandran; Jang-Hoon Ha; Do Kyung Kim (pp. 1934-1938).

The feasibility and perspectives of Al–MCM-41 as hydrogen storage systems were evaluated. The Al–MCM-41 with varying content of aluminum was synthesized by hydrothermal process. Different metal oxides were impregnated over Al–MCM-41 by incipient wetness impregnation (IWI) method. The crystallnity of the samples were interrogated by powder X-ray diffraction. The textural properties were measured by N₂ sorption method. The structural properties were established by Transmission Electron Microscope (TEM). The gas chromatogram indicates that hydrogen uptake in Al–MCM-41 is strongly dependent on density of Brønsted acid sites and the amount of metal oxide (especially NiO).

Keywords: Hydrogen; Storage; MCM-41; Nickel; Impregnation

The selective catalytic oxidation of methane to methyl bisulfate at ambient pressure by Beata Michalkiewicz; Patryk Kosowski (pp. 1939-1942).

The selective catalytic oxidation of methane in 25wt.% oleum to methyl bisulfate at ambient pressure in presence of PtCl₄ catalyst was investigated. The reaction between methane and sulfuric acid took place at atmospheric pressure if the mass transfer between gas and liquid was sufficient. The process was carried out at 130–220°C in absorption reactor packed with glass balls 1.5–7mm in diameter.

Keywords: Methane; Methyl bisulfate; Oleum; PtCl; ₄

Hybridized synergy effect among TiO₂, Pt and graphite silica on photocatalytic hydrogen production from water–methanol solution by Miyuki Ikeda; Yoshihumi Kusumoto; Yohei Yakushijin; Shouichi Somekawa; Pascaline Ngweniform; Bashir Ahmmad (pp. 1943-1946).

The photocatalytic production of hydrogen gas from aqueous methanol solution was performed using powdered mixtures of graphite silica (GS) and platinized TiO₂ (Pt/TiO₂) or those of GS, Pt and TiO₂. The addition of GS to Pt/TiO₂ resulted in the decrease of the amount of H₂ gas, whereas the addition of GS to mixtures of TiO₂ and Pt led to the incremental production of H₂ gas. This effect is attributed to the aggregation of GS, TiO₂ and Pt in suspension. The new additional electron transfer process of TiO₂→Pt→GS caused the increment of the amount of hydrogen gas.

Keywords: Titanium dioxide; Platinum powder; Graphite silica; Hydrogen gas; Water–alcohol mixture; Photocatalysis

The study of the uncalcined Au catalyst and inorganic salts on direct gas-phase epoxidation of propylene by Fushan Wang; Caixia Qi; Jiantai Ma (pp. 1947-1952).

This paper presents the results of the propylene epoxidation in co-presence of hydrogen and oxygen on both dried and calcined Au catalysts, which were prepared by liquid grafting method using Me₂Au(acac) as a precursor and trimethylsilylated Ti-MCM-48 as a support. The calcined catalyst shows PO activity at temperatures much higher and wider than the dried one. Addition of inorganic salts greatly modified the catalytic behaviors. CsNO₃ could be a promising promoter whereas KBr led to the production of propionaldehyde instead of propylene oxide.

Keywords: Gold catalyst; Propylene epoxidation; Silylation; Promoter; Me; ₂; Au(acac)

Thermally differential methanation – A novel method to realize highly selective removal of CO from H₂-rich reformates by Zhan-Guo Zhang; Guangwen Xu (pp. 1953-1956).

Temperature-programmed methanations of CO in both He-diluted and reformate-simulated CO–CO₂–H₂ mixtures over a commercially available 0.5% Ru/Al₂O₃ catalyst have revealed that CO methanation always occurred earlier than that of CO₂ at lower temperatures and the temperature where CO₂ started methanating and the corresponding remaining CO decreased with decreasing initial CO content in the feed. This, while confirming the prior methanation of CO over CO₂, indicates that the fully selective CO methanation is possible. Thus, a novel method called thermally differential methanation was proposed and a totally 820h long term, simplified thermally differential methanation was conducted to verify the effectiveness of the method on realizing simultaneously the full selectivity and a satisfactorily deep removal of CO from H₂-rich reformates for PEFC application.

Keywords: CO removal; Thermally differential methanation; Ru catalyst; PEFC

Comparative study of iron-based Fischer–Tropsch synthesis catalyst promoted with potassium or sodium by Xia An; Bao-shan Wu; Hai-Jun Wan; Ting-Zhen Li; Zhi-Chao Tao; Hong-Wei Xiang; Yong-Wang Li (pp. 1957-1962).

FeCu/SiO₂ catalysts, in which K or Na promoter is incorporated respectively, are prepared by a combination method of continuous co-precipitation and spray drying technology. The catalysts were characterized by temperature-programmed desorption and Mössbauer spectroscopy. The Fischer–Tropsch synthesis (FTS) performance of the catalysts was studied in a continuously stirred tank slurry reactor. The basicity of the K-promoted catalyst is enhanced, as demonstrated by CO₂-TPD results. MES results show that sodium can weaken the dispersion of α-Fe₂O₃ phase; either potassium or sodium can promote carburization of the catalyst, while the effect of sodium is weaker. FTS results indicate that the addition of K or Na can improve the catalyst activity, and shift the product distribution to heavy hydrocarbons to the different extent.

Keywords: Potassium; Sodium; Promoter; Fischer–Tropsch synthesis; Iron-based catalyst

Alumina supported copper nanoparticles for aziridination and cyclopropanation reactions by M. Lakshmi Kantam; V. Swarna Jaya; M. Jaya Lakshmi; B. Ramachandra Reddy; B.M. Choudary; S.K. Bhargava (pp. 1963-1968).

Alumina supported copper (Cu–Al₂O₃) nanoparticles were prepared and applied for the aziridination of olefins employing [ N-(p-tolylsulfonyl)imino]phenyliodinane (PhI=NTs) as nitrene source to afford the corresponding 3-membered cyclic compounds in moderate to excellent yields. Cyclopropanation of several olefins was also carried out by using Cu–Al₂O₃ nanoparticles and ethyl diazoacetate as a carbene source. The catalyst was recovered by simple centrifugation and reused for four cycles.

Keywords: Alumina; Copper nanoparticles; Aziridination; Cyclopropanation; Reusability

A novel solid superbase of Eu₂O₃/Al₂O₃ and its catalytic performance for the transesterification of soybean oil to biodiesel by Xu Li; Guanzhong Lu; Yanglong Guo; Yun Guo; Yanqin Wang; Zhigang Zhang; Xiaohui Liu; Yunsong Wang (pp. 1969-1972).

A novel solid superbase catalyst of Eu₂O₃/Al₂O₃ was prepared and its basic strength reached 26.5 measured by indicators according to Hammett scale. The catalytic activity of Eu₂O₃/Al₂O₃ was evaluated for the transesterification of soybean oil with methanol to biodiesel in the fixed bed reactor and under atmospheric pressure. The results show that Eu₂O₃/Al₂O₃ is an excellent catalyst for the transesterification of soybean oil, and the conversion of soybean oil can reach 63.2% at 70°C for 8h.

Keywords: Eu; ₂; O; ₃; /Al; ₂; O; ₃; Solid superbase catalyst; Biodiesel; Soybean oil; Catalytic transesterification

HClO₄–SiO₂ as a novel and recyclable catalyst for the synthesis of 2,4,6-triarylpyridines under solvent-free conditions by Lingaiah Nagarapu; Aneesa; Rakesh Peddiraju; Satyender Apuri (pp. 1973-1976).

A simple and efficient synthesis of 2,4,6-triarylpyridines using a variety of aromatic and heteroaromatic aldehydes in the presence of solid-supported perchloric acid (HClO₄–SiO₂) as a heterogeneous catalyst at 120°C under solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, shorter reaction times (4–6h), milder conditions and the catalyst exhibited remarkable reusable activity.

Keywords: Solid-supported perchloric acid; 2,4,6-triarylpyridines; One-pot synthesis; Shorter reaction times; Reusable activity

An XPS evidence of the effect of the electronic state of Pd on CH₄ oxidation on Pd/ γ–Al₂O₃ catalysts by G. Corro; O. Vázquez-Cuchillo; F. Banuelos; J.L.G. Fierro; M. Azomoza (pp. 1977-1980).

In this work, we investigated the catalytic activity of 2% Pd/ γ–Al₂O₃ and 2% Pd–1% Sn/ γ–Al₂O₃ for CH₄ oxidation in lean conditions in the presence and in the absence of SO₂ in the reaction feed. The catalysts were studied by the Pd3 d_5/2 electron binding energy values determined by XPS analysis. Sulfates formation and/or tin addition to Pd/Al₂O₃ resulted in an increase of the Pd3 d_5/2 electron binding energy. Results showed a direct relation between Pd activity for CH₄ oxidation and the degree of oxidation of Pd species.

Keywords: Methane oxidation; NGV’s emissions; Pd-Sn catalysts; Sulfur deactivation

Peroxo and superoxo anions: A DFT study on Fe/ZSM-5 zeolite by Gang Yang; Lijun Zhou; Xianchun Liu; Xiuwen Han; Xinhe Bao (pp. 1981-1984).

Metal peroxide species are the active sites in lots of solid-state and enzyme catalytic systems. With density functional calculations, the configurations of peroxide and superoxide anions in Fe/ZSM-5 zeolite were first resolved. The presence of superoxide anion was validated, which is less stabilized than the peroxide anion, especially at higher temperatures. It acts as the precursor to the active peroxide anion. Raman frequencies of these two species were analyzed considering¹⁸O/¹⁶O isotope effects. The present results are in fine agreement with previous theoretical and experimental results.

Keywords: Active site; Density functional; Peroxide; Superoxide; Fe/ZSM-5 zeolite

Forced thermal cycling of catalytic reactions: Experiments and modelling by Søren Jensen; Jakob L. Olsen; Sune Thorsteinsson; Ole Hansen; Ulrich J. Quaade (pp. 1985-1990).

Recent studies of catalytic reactions subjected to fast forced temperature oscillations have revealed a rate enhancement increasing with temperature oscillation frequency. We present detailed studies of the rate enhancement up to frequencies of 2.5Hz. A maximum in the rate enhancement is observed at about 1Hz. A model for the rate enhancement that includes the surface kinetics and the dynamic partial pressure variations in the reactor is introduced. The model predicts a levelling off of the rate enhancement with frequency at about 1Hz. The experimentally observed decrease above 1Hz is explained by dynamic thermal limitations of the reactor.

Keywords: PACS; 82.65.+r; 82.65.s; 82.40.BjMicroreactor; Catalysis; Temperature cycling

An efficient synthesis of 2,4,6-triarylpyridines catalyzed by heteropolyacid under solvent-free conditions by Majid M. Heravi; Khadijeh Bakhtiari; Zohreh Daroogheha; Fatemeh F. Bamoharram (pp. 1991-1994).

Preyssler type heteropolyacid is found to be an efficient catalyst for the synthesis of 2,4,6-triarylpyridines in good yields. The catalyst is recycled and reused several times.

Keywords: Preyssler type heteropolyacid; 2,4,6-Triarylpyridines; Krohnke pyridines; Solvent-free condition; H; ₁₄; [NaP; ₅; W; ₃₀; O; ₁₁₀; ]

Nitroaldol reaction in fluorous media: An important improvement of the chemoselective addition of aldehyde by Wen-Bin Yi; Xin Wang; Chun Cai (pp. 1995-1998).

Ytterbium perfluorooctanesulfonate [Yb(OPf)₃] catalyses the highly efficient Henry reaction in the presence of a catalytic amount of a novel perfluoroalkylated-pyridine as a ligand in a fluorous biphase system (FBS) composed of toluene and perfluorodecalin. An unprecedented chemoselective addition of aldehydes among various carbonyl compounds and the robustness of the catalytic system for recycling using by simple phase-separation were obtained.

Keywords: Chemoselective addition; Henry reaction; Ytterbium perfluorooctanesulfonate; Perfluorinated ligand; Fluorous biphasic catalysis

Selective hydrogenation of o-chloronitrobenzene over palladium supported nanotubular titanium dioxide derived catalysts by Lucky M. Sikhwivhilu; Neil J. Coville; Basha M. Pulimaddi; Jayasri Venkatreddy; Venkataraman Vishwanathan (pp. 1999-2006).

Titania derived nanotubes were synthesized by treating P-25 Degussa TiO₂ with a concentrated (18M) KOH solution. Ageing the material in KOH solution for 2 days resulted in formation of tubular titania and Raman analysis revealed that the material has a titanate structure. The synthesized material was used as a catalyst support for the hydrogenation of ortho-chloronitrobenzene ( o-CNB) with Pd as the active phase. The vapour-phase hydrogenation of o-CNB was carried out in ethanol at 523K and atmospheric pressure over a Pd/TiO₂ derived nanotube catalyst (Pd/TiO₂-M). Pd/TiO₂-M gave complete conversion (100%) of o-CNB with the selectivity to ortho-chloroaniline ( o-CAN) of 86%. The stability of the Pd/TiO₂-M catalyst was tested over 5h during which time the conversion slowly dropped to 80% (selectivity 93%) due to catalyst poisoning. TPR analysis revealed the existence of a strong palladium-support interaction and this was found to be crucial to the overall activity of the catalyst.

Keywords: Nanotubular titanate; Titanium dioxide; ortho; -Chloronitrobenzene; ortho; -Chloroaniline; Hydrogenation

On the location of different titanium sites in Ti–OMS-2 and their catalytic role in oxidation of styrene by Hadi Nur; Fitri Hayati; Halimaton Hamdan (pp. 2007-2011).

Octahedral manganese oxide molecular sieves (OMS-2) modified by impregnation of TiO₂ exhibit a higher catalytic activity for oxidation of styrene with tert-butylhydroperoxide in comparison to titanium-incorporated OMS-2, where the styrene conversions were ca. 70% and 45–50%, respectively. The framework of titanium species has no effect on the enhancement of catalytic activity, while the non-framework of titanium species induces a synergetic effect that enhances the oxidation of styrene with tert-butylhydroperoxide.

Keywords: Titanium-incorporated octahedral manganese oxide molecular sieves; Non-framework titanium; Oxidation of styrene

Efficient synthesis of 1,3-dioxanes catalyzed by trifluoromethanesulfonic acid using formalin as formaldehyde source by Yuying Du; Fuli Tian (pp. 2012-2016).

Prins cyclizations of styrene derivatives were smoothly conducted in a water solution of formaldehyde using trifluoromethanesulfonic acid (TfOH) as catalyst. While excellent yield was obtained in the Prins cyclization of styrene in the presence of TfOH, low yields or no reaction were observed when other traditional minimal acids catalysts were used.

Keywords: Trifluoromethanesulfonic acid; Prins cyclization; 1,3-Dioxane; Formalin

Oxovanadium(IV) complex of β-alanine derived ligand immobilised on polystyrene for the oxidation of various organic substrates by Mannar R. Maurya; Sweta Sikarwar; Maneesh Kumar (pp. 2017-2024).

Tridentate Schiff base (H₂fsal-β-ala) obtained from 3-formylsalicylic acid and β-alanine has been covalently bonded to divinylbenzene cross-linked chloromethylated polystyrene. This chelating resin, abbreviated as PS-H₂fsal-β-ala (PS=polymeric support), reacts with vanadyl sulfate in DMF to give polymer bound complex, PS-[VO(fsal-β-ala)·DMF], formation of which has been confirmed by various physiochemical methods such as elemental analysis, FT-IR and diffused reflectance spectra, thermo gravimetric analysis, and scanning electron micrograph. Catalytic potential of PS-[VO(fsal-β-ala)·DMF] has been tested for the oxidation of various organic substrates such as benzene, cumene, naphthalene, cyclohexane, styrene, cyclohexene and trans-stilbene in the presence of 30% H₂O₂ as an oxidant. Oxidation products obtained from each substrate have been characterised by gas chromatography and their identities confirmed by gas chromatography–mass spectrometry.

Keywords: Chloromethylated polystyrene; Polymer-anchored complex; Oxovanadium(IV) complex; Oxidation reactions

Ethylene polymerization using an asymmetric dinuclear titanocene catalyst carrying a novel 3-oxa-pentamethylene bridge by Xu Li; Xutao Zhao; Bochao Zhu; Feng Lin; Junquan Sun (pp. 2025-2031).

The asymmetric 3-oxa-pentamethylene bridged dinuclear titanocenium complex (CpTiCl₂)₂ ( η⁵-C₉H₆(CH₂CH₂ OCH₂CH₂)- η⁵-C₅H₃ CH₃) (1) has been prepared, characterized by¹H NMR spectroscopy and elemental analysis, and after activation with MAO tested as a homogenous catalyst for the polymerization of ethylene. The results show that the catalytic activity of1 as well as the molecular weight of the produced polyethylene are higher than those using the alkylidene bridged asymmetric dinuclear metallocenes (CpTiCl₂)₂ ( η⁵-C₉H₆(CH₂)_n- η⁵-C₅H₄), n=3 (4), 4 (5). The molecular weight distribution of polyethylene produced with1/MAO reaches 11.00 and the HT-GPC curve shows a bimodal distribution. The melting point of the polyethylene obtained by1/MAO is higher than 135°C and the¹³C NMR spectrum of PE shows only one strong signal at 30ppm for the methylene units indicating a highly linear and crystalline polymer.

Keywords: Asymmetric dinuclear titanocene catalysts; Ethylene polymerization; Polyethylene

On the structure-sensitivity of 2-butanol dehydrogenation over Cu/SiO₂ cogelled xerogel catalysts by Stéphanie Lambert; Caroline Cellier; Fabrice Ferauche; Éric M. Gaigneaux; Benoît Heinrichs (pp. 2032-2036).

Cu/SiO₂ cogelled xerogel catalysts were synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Cu with 3-(2-aminoethylamino)-propyltrimethoxysilane (EDAS). The resulting catalysts are composed of metallic crystallites with a diameter of about 3nm located inside microporous silica particles and larger metallic particles with a diameter of 8–30nm located outside silica network. Cu/SiO₂ catalysts were tested for 2-butanol dehydrogenation. This reaction over Cu/SiO₂ cogelled xerogel catalysts is a structure-sensitive reaction: large metallic particles located outside silica particles are responsible for the dehydrogenation reaction, while small metallic particles located inside silica particles do not participate to the reaction.

Keywords: Sol–gel process; Cogelification; Copper catalysts; 2-Butanol dehydrogenation; Structure-sensitive reaction

Manganese ferrite nanoparticles synthesized through a nanocasting route as a highly active Fenton catalyst by Teresa Valdés-Solís; Patricia Valle-Vigón; Sonia Álvarez; Gregorio Marbán; Antonio B. Fuertes (pp. 2037-2042).

Spinel ferrite MnFe₂O₄ nanoparticles were synthesized by means of a nanocasting technique using a low-cost mesoporous silica gel as a hard template. The magnetic nanoparticles, of <10nm diameter and with a surface area of around 100m²/g, were tested as a heterogeneous Fenton catalyst for the decomposition of hydrogen peroxide under neutral and basic conditions. This catalyst shows a much higher activity than previous heterogeneous catalysts reported in the literature, which is mainly ascribed to its small particle size. Furthermore, the magnetic catalyst can be easily separated from the reaction medium by means of an external magnetic field. The effects of residual silica and the purity of the catalyst (hematite formation) on catalytic activity have been studied and correlated. The results obtained show this catalyst to be a suitable candidate for the removal of pollutants in wastewaters by means of the Fenton heterogeneous reaction.

Keywords: Hydrogen peroxide decomposition; Template method; Manganese ferrite spinel; Nanoparticle; Heterogeneous Fenton reaction

Chemo-enzymatic epoxidation of (+)-3-carene by Marcelo A. Moreira; Maria G. Nascimento (pp. 2043-2047).

The chemo-enzymatic epoxidation of (+)-3-carene using peroxy acids formed in situ, in the presence of H₂O₂ and enzymes from different sources is here presented. The reaction proceeded efficiently and various parameters of the experimental conditions were evaluated. The product was obtained in high yields and kept the optical purity of the substrate.

Keywords: Epoxidation; Lipases; Proteases; (+)-3-carene

Significant yield improvement in the stereoselective synthesis of allyl cyanides from Baylis–Hillman derivatives in aqueous medium under the influence of the phase-transfer catalyst by Vijay Singh; Richa Pathak; Sanjay Batra (pp. 2048-2052).

The nucleophilic reaction of NaCN with the acetyl derivative of Baylis–Hillman adducts in the presence of a phase-transfer catalyst in aqueous medium stereoselectively affords the corresponding allyl cyanides in a short period and excellent yields.

Keywords: Baylis–Hillman; Allyl cyanide; NaCN; Phase-transfer catalyst; Water

Alkaline earth metal oxides as solid bases for ligand-free Heck reaction by Fengxi Chen; Ivy Lin; Henan Li; Geok Joo Gan; Kelvin Toh; Lijun Tham (pp. 2053-2058).

Alkaline earth metal oxides (MO, M=Mg, Ca, Sr and Ba) are investigated as solid bases for ligand-free Heck reaction (Pd concentration: 0.05mol%). SrO is efficient to promote Heck arylation of styrene with bromobenzene (BB). However, aryl amination of BB to form N, N-dimethylaniline is also observed with SrO. CaO- n particles ( n: calcination temperature) are prepared by calcination of dried Ca(NO₃)₂ aqueous solution at 700 or 900°C. The CaO- n particles outperform other alkaline earth metal oxides considering both BB conversion and selectivity to Heck products. The CaO-900 particles show better performance than the CaO-700 particles. This is attributed to their platelet morphology with sharp edges and corners and the preferential growth along the (111) crystal plane.

Keywords: Ligand-free Heck reaction; Solid base; Alkaline earth metal oxides

Multi-walled carbon nanotubes (MWNTs) as an efficient catalyst for catalytic wet air oxidation of phenol by Shaoxia Yang; Wanpeng Zhu; Xiang Li; Jianbing Wang; Yunrui Zhou (pp. 2059-2063).

Multi-walled carbon nanotubes (MWNTs) were used as a catalyst for catalytic wet air oxidation (CWAO) of phenol in a batch reactor. SEM, TEM and FT-IR technique were applied to investigate the microstructure and the surface functional group of the MWNTs. When the carboxylic groups (–COOH) are grafted onto the surface of the MWNTs, the functionalized MWNTs exhibit a good catalytic activity in CWAO of phenol. At a reaction temperature of 160°C, oxygen pressure of 2.0MPa and a phenol concentration of 1000mg/L, 100% phenol and 76% TOC are removed after 120min reaction.

Keywords: Carbon nanotubes; Multi-walled carbon nanotubes; Catalytic wet air oxidation; Phenol

Highly efficient chemoselective catalytic hydrogenation of diaryl substituted α,β-unsaturated nitriles/carbonyls using homogeneous Pd(OAc)₂/PPh₃ catalyst by Malhari D. Bhor; Mayur J. Bhanushali; Nitin S. Nandurkar; Bhalchandra M. Bhanage (pp. 2064-2068).

α,β-unsaturated nitriles are chemoselectively hydrogenated to corresponding saturated nitriles with Pd(OAc)₂/PPh₃ as a homogeneous catalytic system using atmospheric pressure of molecular hydrogen. Various parameters like catalyst concentration, role of solvents, variation in the reaction temperature were screened and optimized reaction conditions were successfully used for chemoselective hydrogenation of other diaryl substituted α,β-unsaturated nitriles. The present catalytic system have also been used for hydrogenation of α,β-unsaturated carbonyls at atmospheric pressure of hydrogen.

Keywords: Unsaturated nitrile; Chemoselectivity; Homogeneous hydrogenation; Palladium; P-ligands

The catalytic activity of immobilized on modified silica metalloporphyrins bearing antioxidative 2,6-di- tert-butylphenol pendants by Elena R. Milaeva; Olga A. Gerasimova; Anton L. Maximov; Ekaterina A. Ivanova; Eduard A. Karachanov; Nick Hadjiliadis; Maria Louloudi (pp. 2069-2073).

A comparative study of the catalytic activity of supported manganese(III) and iron(III) chlorides of meso-tetrakis(3,5-di- tert-butyl-4-hydroxyphenyl)porphyrin (R₄PMnCl, R₄PFeCl) and meso-tetraphenylporphyrin (TPPMnCl, TPPFeCl) is reported. The metalloporphyrins have been immobilized via coordination bond on the surface of two series of imidazole modified silica, imidazole propyl silica (IPS) and imidazole 3-(glycidyloxypropyl) silica (IGOPS). The heterogenised catalysts have been evaluated for hydrocarbon oxidation by sodium periodate. The critical role of 2,6-di- tert-butylphenol groups on the periphery of porphyrin ring in their catalytic activity has been evaluated and pertinent structural and mechanistic aspects are discussed.

Keywords: Supported metalloporphyrins; 2,6-di-; tert; -butylphenol; Biomimetic oxidation

Potassium leaching during triglyceride transesterification using K/γ-Al₂O₃ catalysts by D. Martín Alonso; R. Mariscal; R. Moreno-Tost; M.D. Zafra Poves; M. López Granados (pp. 2074-2080).

A K/γ-Al₂O₃ catalyst was prepared using the wet impregnation method with K₂CO₃ as a precursor salt. During the activation process, a clear interaction between potassium carbonate-derived species and the support took place resulting in the formation of K aluminate-like species, as observed by evolved gas analysis by mass spectrometry (EGA-MS) and infrared spectroscopy (FTIR). This catalyst was tested in the transesterification of sunflower oil with methanol, achieving a methyl ester yield close to 100% after 1h. However, when it was used in successive runs the catalyst showed a strong decrease in its catalytic performance. It is established experimentally that the performance in the first run was mainly due to a homogeneous contribution from active basic species dissolved in methanol. The leaching of potassium species in the reaction media was not avoided although a clear interaction between active phase and support was observed. The present work stresses the obligation of the reutilization and of the verification of the leaching of active species in analogous catalytic systems based on alkaline and alkaline-earth metal oxides when used in the transesterification reaction with methanol.

Keywords: Biodiesel; Sunflower oil; Transesterification; Solid catalyst; Leaching; Homogeneous catalytic contribution

Catalytic behaviour of Pt or Pd metal nanoparticles–zeolite bifunctional catalysts for n-pentane hydroisomerization by A. Brito; F.J. García; M.C. Alvarez-Galván; M.E. Borges; C. Díaz; V.A. de la Peña O’Shea (pp. 2081-2086).

Bifunctional catalysts based on acidified Mordenite or ZSM-5 and platinum or palladium as metal function, were tested for n-pentane hydroisomerization. Two methods were used to introduce platinum: wetness impregnation and microemulsion; palladium was introduced via an organometallic complex. A lower catalytic activity was obtained for palladium catalyst in comparison with platinum samples which is explained by the lower activity of Pd in the dehydrogenation reaction step. Different catalytic behaviour of systems based on Mordenite and ZSM-5 was attributed to zeolite pore structure. The uncompleted removal of surfactant during calcination could explain the lower activity showed by catalysts prepared by microemulsion.

Keywords: n; -Pentane; Hydroisomerization; Platinum; Palladium; Mordenite; ZSM-5

High-valent tin(IV) porphyrin, Sn^IV(TPP)(BF₄)₂, as an efficient catalyst for the ring-opening of epoxides by Majid Moghadam; Shahram Tangestaninejad; Valiollah Mirkhani; Iraj Mohammadpoor-Baltork; S. Abdolmanaf Taghavi (pp. 2087-2095).

The new electron deficient tin(IV)tetraphenylporphyrinato tetrafluoroborate, [Sn^IV(tpp)(BF₄)₂], was used as an efficient catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. Conversion of epoxides to thiiranes was also performed efficiently in the presence of this catalyst. This catalyst efficiently catalyzed conversion of epoxides to 1,3-dioxolanes. The results showed that replacing ofBF4- with Cl⁻ converts the tin(IV) porphyrin to an efficient Lewis acid.

Keywords: Epoxides; Ring-opening; Tin porphyrin; Electron deficient

Novel promoting effect of SO₂ on the selective catalytic reduction of NO_x by ammonia over Co₃O₄ catalyst by Rui Ke; Junhua Li; Xi Liang; Jiming Hao (pp. 2096-2099).

Spinel nano-Co₃O₄ was prepared by solid-state reaction at room temperature and investigated for selective catalytic reduction of NO_x by NH₃ (NH₃-SCR). Although suffering from pore filling and plugging, treatment of this catalyst by SO₂ showed novel promoting effect on NH₃-SCR above 250°C. Bulk cobalt sulfate was observed over the sulfated Co₃O₄ with XRD, which would be an active component for NH₃-SCR. The sulphated Co₃O₄ catalyst exhibited good resistance to SO₂ (500ppm, 100ppm) and 10% H₂O at a space velocity of about 25000h⁻¹ at 300°C, as tested for 12h.

Keywords: Co; ₃; O; ₄; Selective catalytic reduction; Ammonia; SO; ₂; resistance; Cobalt sulfate

Opposite effect of gas phase H₂O₂ on photocatalytic oxidation of acetone and benzene vapors by A.V. Vorontsov (pp. 2100-2104).

The effect of additions of gas phase H₂O₂ was measured for gas phase photocatalytic oxidation of organic vapors. Photocatalytic oxidation of benzene vapor over TiO₂ in a flow reactor resulted in a quick catalyst deactivation. Additions of gas phase H₂O₂ into the reactor feed provided enhanced and sustained oxidation of benzene vapor. The increase of inlet H₂O₂ vapor concentration from 0 to about 1000ppm led to the one order of magnitude growth of benzene vapor complete oxidation rate. The highest rate of 1.1nmol/s was observed at C₆H₆ concentration 124ppm and H₂O₂ concentration 1000ppm. In the case of acetone vapor photocatalytic oxidation, the rate of complete oxidation in the flow reactor decreased with an increase of gas phase H₂O₂ inlet concentration. TiO₂ Degussa P25 provided higher oxidation rate in the presence of H₂O₂ than pure anatase TiO₂.

Keywords: Hydrogen peroxide; Photocatalysis; Titanium dioxide; Rutile; Reactivation; Aromatic compounds; Deactivation; Surface peroxocomplex

Calibrated Co₃O₄ nanoparticles patterned in SBA-15 silicas: Accessibility and activity for CO oxidation by I. Lopes; A. Davidson; C. Thomas (pp. 2105-2109).

The catalytic performances in CO oxidation of Co₃O₄ nanoparticles patterned in the porosity of SBA-15 silicas are investigated. Accessibility limitations of the reactants to the catalytic sites are clearly revealed, when the Co₃O₄ nanoparticles are embedded in the SBA-15 pores. Despite these limitations, the synthesised Co₃O₄ nanoparticles exhibit promising CO oxidation properties.

Keywords: CO oxidation; Co; ₃; O; ₄; SBA-15; Nanocasting; Catalysts; Site accessibility

The catalytic activity of CuO–CeO₂ mixed oxides for diesel soot oxidation with a NO/O₂ mixture by Xiaodong Wu; Qing Liang; Duan Weng; Zhenxiang Lu (pp. 2110-2114).

Copper doped ceria and ceria–zirconia mixed oxides were synthesized using the citric acid sol–gel method. The temperature-programmed oxidation (TPO) results showed that the Cu modification improved the low-temperature activity and the selectivity to CO₂ of ceria for soot oxidation in the presence of NO and excess oxygen even after ageing at 800°C for 20h in flow air. Meanwhile, not only the segregation of Cu and sintering of CuO, but also the separation of Ce- and Zr-rich phases worsened the activity of the Cu–Ce–Zr catalyst after the high-temperature calcination.

Keywords: Copper oxide–ceria; Soot; Selectivity; Nitrate storage capacity; Thermal stability

Hydrogenation of quinoline by ruthenium nanoparticles immobilized on poly(4-vinylpyridine) by Roberto A. Sánchez-Delgado; Nataliya Machalaba; Nkechia Ng-a-qui (pp. 2115-2118).

A series of catalysts composed of ruthenium nanoparticles immobilized on poly(4-vinylpyridine) was prepared by NaBH₄ reduction of RuCl₃·3H₂O in methanol in the presence of the polymer; TEM measurements of a 10wt% Ru/P4VPy material indicate that ruthenium particles of 1–2nm predominate. This catalyst is efficient for the selective hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline at 100–120°C and 30–40bar H₂. The activity increases with hydrogen pressure up to 40bar but is essentially independent of quinoline concentration. Polar solvents, triethylamine, and acetic acid enhance catalytic performance, suggesting an ionic mechanism involving heterolytic hydrogen activation.

Keywords: Hydrogenation; Quinoline; Ruthenium; Nanoparticles; Polymer-supported; Poly(4-vinylpyridine)

Iron(III) trifluoroacetate and trifluoromethanesulfonate: Recyclable Lewis acid catalysts for one-pot synthesis of 3,4-dihydropyrimidinones or their sulfur analogues and 1,4-dihydropyridines via solvent-free Biginelli and Hantzsch condensation protocols by Hadi Adibi; Heshmat Allah Samimi; Mojtaba Beygzadeh (pp. 2119-2124).

Iron(III) trifluoroacetate [Fe(CF₃CO₂)₃] or trifluoromethanesulfonate [Fe(CF₃SO₃)₃] catalyzes three component coupling of β-dicarbonyl compounds, aldehydes and urea or thiourea to afford the corresponding 3,4-dihydropyrimidinones or their sulfur analogues under solvent-free conditions. Also, these catalysts were used for one-pot synthesis of 1,4-dihydropyridines via solvent-free Hantzsch reaction. This new protocol allows the recycling of catalysts with no loss in their potency.

Keywords: 1,4-Dihydropyridines; 3,4-Dihydropyrimidinones; Trifluoroacetate; Trifluoromethanesulfonate

A high performance bimetallic catalyst for photo-Fenton oxidation of Orange II over a wide pH range by Frank L.Y. Lam; Xijun Hu (pp. 2125-2129).

A bimetallic catalyst supported on MCM-41 was synthesized by chemical vapour deposition and evaluated in the photo-Fenton degradation of Orange II. An in situ oxidation method recently developed in our group was applied to stabilize the metal catalyst supported on MCM-41, achieving an extremely low metal leaching level. This FeCu/MCM-41 shows TOC removals of 93%, 83%, and 78% at pHs of 3, 5.5, and 7, respectively, and maintains its high catalytic activity after 10 consecutive runs. This catalyst successfully overcomes the two problems faced by the heterogeneous photo-Fenton process – metal leaching and narrow working pH range.

Keywords: Bimetallic catalyst; Chemical vapor deposition; Fenton; Stability

A fast, efficient and eco-friendly procedure to prepare isatin ketals by Núbia Moura Ribeiro; Angelo da Cunha Pinto; Bárbara Vasconcellos da Silva; Flávio de Almeida Violante; Marluce Oliveira Dias (pp. 2130-2136).

A fast and efficient solvent-free procedure to prepare isatin ketals has been developed. Three different clays, commercial Montmorillonite K10 (Aldrich Co.) and two natural clays, were used as catalysts. A Brazilian-manufactured microwave oven was used as heat source. Montmorillonite K10 provides the best results.

Keywords: Natural clays; Montmorillonite K10; Isatin; Ketalization

Structure and catalytic activity of POSS-stabilized Pd nanoparticles by Sonia E. Létant; Julie Herberg; Long N. Dinh; Robert S. Maxwell; Randall L. Simpson; Andrew P. Saab (pp. 2137-2142).

Palladium nanoparticles stabilized with polyhedral oligomeric silsesquioxanes have been characterized and determined to function as a heterogeneous catalyst. TEM and SEM studies indicate the material comprises 2–5nm diameter Pd crystallites in a POSS layer, which aggregate to form spherical secondary structures of about 50nm in diameter. Solid-state NMR reveals that the primary interaction between Pd and POSS is through the alkyl-amino functional groups on the POSS cage, in addition to some weak interactions with the cage itself. This material is observed by microbalance measurements to efficiently catalyze the direct hydrogenation of 1,4-diphenylbutadiyne.

Keywords: Catalysis; Nanoparticles; Palladium; POSS

In situ copolymerization of ethylene to linear low-density polyethylene (LLDPE) with calcosilicate (CAS-1) supported dual-functional catalytic system by Hong Xu; Cun-Yue Guo; Mingge Zhang; Hai-Jian Yang; Jinxiang Dong; Guoqing Yuan (pp. 2143-2149).

Calcosilicate (CAS-1) was used for the first time as an effective carrier for simultaneous immobilization of a dual-functional catalytic system consisted of iron-based bis(imino) pyridyl complex (O) and zirconocene compound (C) to form heterogeneous catalyst precursor (CAS-1/O/C). The α-olefins formed formO-catalyzed ethylene oligomerization copolymerized in situ with ethylene to linear low-density polyethylene (LLDPE) under the catalysis ofC in CAS-1/O/C upon addition of cocatalysts as described hereafter. Instead of methylaluminoxane (MAO), triethylaluminum (TEA) was employed to activate the copolymerization reaction with high catalytic activities and smooth kinetic process. Experimental results reflected that the selectivity for lower α-olefins was improved due to the confinement effect of the layered structures of CAS-1, hence greatly increasing the incorporation rate of α-olefins into LLDPE main chains and the branching degree accordingly during the in situ copolymerization of α-olefins and ethylene. The layered structure of CAS-1 endowed the resultant LLDPE with improved thermal stability in addition to higher molecular weights ( M_n).

Keywords: In situ; copolymerization; Ethylene; CAS-1; Support; Dual-functional catalyst

Aminophosphine supported on Al₂O₃ as recoverable catalyst for the Suzuki coupling by Baoda Lin; Zhiqing Liu; Miaochang Liu; Changduo Pan; Jinchang Ding; Huayue Wu; Jiang Cheng (pp. 2150-2152).

In this paper, aminophoshpine was supported on Al₂O₃, which was a very active catalyst for the Suzuki coupling. The reaction condition was mild. The catalyst could use four times with synthetically useful results.

Keywords: Aminophosphine; Recoverable; Suzuki coupling

Role of nitrogen-containing organic compound in plasma exhaust treatment by Yong Nie; Jingyi Wang; Kan Zhong; Liming Wang; Zhicheng Guan (pp. 2153-2158).

Role of nitrogen-containing organic compounds produced during the plasma process on the subsequent of C₂H₄-SCR of NO _x over Ag/γ-Al₂O₃ catalyst at 523K was studied in a two-stage plasma-facilitated catalysis system. Results showed that nitrogen-containing organic compounds (methyl nitrate, ethyl nitrate, nitro methyl) produced in the plasma reactor can improve the subsequent catalytic performance at lower temperature besides NO₂ and aldehyde; more the amounts of nitrogen-containing organic compounds produced after plasma pretreatment, more the amounts of N₂ produced in the subsequent catalysis process, and N₂ selectivity leveled at about 82%.

Keywords: Nitrogen-containing organic compounds; Plasma-facilitated catalysis; NO; _x; N; ₂; selectivity

Synthesis of biodiesel from soybean oil and methanol catalyzed by zeolite beta modified with La³⁺ by Qing Shu; Bolun Yang; Hong Yuan; Song Qing; Gangli Zhu (pp. 2159-2165).

La/zeolite beta was prepared by an ion exchange method and used to synthesize the biodiesel (fatty acid methyl esters, FAME). The La(NO₃)₃ was applied as the ion exchange precursor to incorporate La ion into zeolite beta. The composition of the zeolite beta before and after ion exchange was analyzed by the SEM microphotographs and EDS spectrograms, the Brønsted and Lewis acid sites were investigated by FTIR imaging. The transesterification was carried out in a batch reactor and the composition of the FAME product was determined by a potassium hydroxide saponification method. The syntheses conditions with respect to catalytic activities have been optimized individually. Results of the experiment showed that La/zeolite beta shows higher conversion and stability than zeolite beta for the production of biodiesel, which may be correlated to the higher quantity of external Brønsted acid sites available for the reactants. The product consists of a mixture of monoalkyl esters primarily, and when the methanol/ soybean oil molar ratio was 14.5, reaction temperature at 333K, reaction time 4h and catalyst/soybean oil mass ratio of 0.011, the conversion of triglyceride 48.9wt% was obtained from this optimal reaction condition.

Keywords: Biodiesel; Soybean oil; La/zeolite beta; Transesterification; Solid acid

Effect of Ag addition on the properties of Pd–Ag/TiO₂ catalysts containing different TiO₂ crystalline phases by Kunyaluck Kontapakdee; Joongjai Panpranot; Piyasan Praserthdam (pp. 2166-2170).

Anatase and rutile TiO₂ were used for preparation of the TiO₂ supported Pd and Pd–Ag catalysts for selective hydrogenation of acetylene. It was found that Pd/TiO₂-anatase exhibited higher acetylene conversion and ethylene selectivity than rutile TiO₂ supported ones. However, addition of Ag to Pd/TiO₂-anatase catalyst resulted in lower ethylene selectivity while that of Pd/TiO₂-rutile increased. It is suggested that Ag addition suppressed the beneficial effect of the Ti³⁺ sites presented on the anatase TiO₂ during selective acetylene hydrogenation whereas without Ti³⁺, Ag promoted ethylene selectivity by blocking sites for over-hydrogenation of ethylene to ethane.

Keywords: Pd/TiO; ₂; Pd–Ag/TiO; ₂; Selective acetylene hydrogenation; Crystalline phase

Development of a Pt/TiO₂ catalyst on an anodic alumite film for catalytic decomposition of formaldehyde at room temperature by Lifeng Wang; Qi Zhang; Makoto Sakurai; Hideo Kameyama (pp. 2171-2175).

A Pt/TiO₂ catalyst was prepared on an anodic alumite film and employed in the catalytic decomposition of formaldehyde at room temperature. The results show that the catalyst exhibits good activity toward the decomposition of formaldehyde at room temperature when the anodic alumite film is treated in hot water. Moreover, in accordance with the process requirements, the developed catalyst can be formed into various shapes such as a mesh, plate, fin, serrate etc., because aluminum can be formed into any shapes.

Keywords: Formaldehyde; Pt/TiO; ₂; Structure-catalyst; Anodic alumite film

Soot combustion activity of NO_x-sorbing Cs–MnO_x–CeO₂ catalysts by Kazuhiro Ito; Kouji Kishikawa; Akihisa Watajima; Keita Ikeue; Masato Machida (pp. 2176-2180).

Activities of Cs-loaded MnO_x–CeO₂ for combustion of model diesel soot (carbon black) and sorptive NO uptake have been studied. MnO_x–CeO₂ is a pseudo-solid solution having redox properties favorable for soot oxidation. The addition of Cs not only lowered the temperature of soot ignition ( T_i), but also increased oxidative NO_x adsorption to form nitrate on the surface. Soot ignition over Cs–MnO_x–CeO₂ was further promoted in a stream of NO/O₂, presumably because nitrate on the surface plays a role of an oxidizing agent. Soot ignition started just before sharp desorption of NO_x, suggesting that adsorbed nitrate species would directly interact with soot.

Keywords: Diesel soot combustion; NO; _x; adsorption; Manganese; Cerium; Cesium

Microwave-accelerated solvent-free aerobic oxidation of benzyl alcohol over efficient and reusable manganese oxides by Yang Su; Lu-Cun Wang; Yong-Mei Liu; Yong Cao; He-Yong He; Kang-Nian Fan (pp. 2181-2185).

A new facile and cost-effective process involving the solvent-free oxidation of benzyl alcohol using molecular oxygen as oxidant under controlled microwave irradiation has been developed for the production of chlorine-free benzaldehyde. Influence of different catalyst parameters (different manganese oxides and other kinds of transition metal oxides) and reaction conditions (reaction period and temperature) on the process performance has been studied. Under optimized reaction conditions, the MnO₂ catalyst showed a superior catalytic performance in the highly selective oxidation of benzyl alcohol as compared to other manganese oxide materials such as MnO, Mn₂O₃ and Mn₃O₄. Moreover, a very stable catalytic activity as a function of cycling test was observed for the MnO₂ catalyst.

Keywords: Benzaldehyde; Manganese oxides; Aerobic oxidation; Microwave irradiation; Solvent-free

Non-oxidative dehydrogenation of ethane to ethylene over chromium catalysts prepared from layered double hydroxide precursors by Andrey Tsyganok; Richard G. Green; Javier B. Giorgi; Abdelhamid Sayari (pp. 2186-2193).

Non-oxidative dehydrogenation of ethane into ethylene at 700°C over reductively pretreated Cr–Mg–Al and Cr–Mg mixed oxide catalysts has been studied. The catalysts were prepared from layered double hydroxide (LDH) precursors that contained various species of chromium (i.e., cationic Cr(III), complex of Cr(III) with an anionic chelating agent, and chromate anion). Synthesized materials were characterized with powder X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy techniques. It was shown that the surface area of the LDH-derived mixed oxides, their catalytic performance, coking ability, and susceptibility to sintering were highly dependent on the method used for introducing chromium into the LDH precursors of the catalysts.

Keywords: Ethane dehydrogenation; Ethylene production; Supported chromium catalysts; Layered double hydroxides

Photocatalytic N-alkylation of benzylamine in microreactors by Yoshihisa Matsushita; Nobuko Ohba; Shinji Kumada; Tadashi Suzuki; Teijiro Ichimura (pp. 2194-2197).

A photocatalytic process of N-alkylation of benzylamine in alcohol media was successfully observed by using microreactors with immobilized Pt-free TiO₂ as well as Pt-loaded TiO₂, while it has been reported that the N-alkylation did not occur by the irradiation of Pt-free TiO₂ in conventional batch reactors. The use of continuous-flow microreactor inhibited the formation of N, N-dialkylation products. These results suggest the possibilities of a catalytic microreaction system on organic photoreactions.

Keywords: Microreactor; Titania; Photocatalytic reaction; UV-LED; Alkylation

Lithium perchlorate promoted highly regioselective ring opening of epoxides under solvent-free conditions by Najmodin Azizi; Bahareh Mirmashhori; Mohammad R. Saidi (pp. 2198-2203).

A simple and efficient synthesis of diol diesters, protected chlorohydrins, chlorohydrins and β-hydroxy azides with acetyl or benzoyl, TMSN₃ and TMSCl groups has been achieved by ring opening of epoxides with acetic anhydride, acetyl chloride or benzoyl chloride and TMSN₃ using catalytic amount of lithium perchlorate under solvent-free conditions. All reactions proceeded in short times and afforded the corresponding products in good to excellent yields under mild reaction conditions. LiClO₄ shows enhanced reactivity for the ring opening of epoxides under solvent-free conditions, therefore, reducing the reaction times dramatically and improved the yields and amount of catalyst.

Keywords: Lithium perchlorate; Diol diesters; Chlorohydrins; β-Hydroxy azides; Solvent-free

Plasma catalytic methane conversion over sol–gel derived Ru/TiO₂ catalyst in a dielectric-barrier discharge reactor by Seung-Soo Kim; Byeongwan Kwon; Jinsoo Kim (pp. 2204-2207).

Plasma catalytic methane conversion was carried out in the presence of sol–gel derived Ru/TiO₂ catalysts within a dielectric-barrier discharge (DBD) reactor. Plasma-assisted reduction (PAR) was applied to reduce the prepared Ru/TiO₂ catalysts in DBD reactor, and most of the catalysts were successively reduced by PAR within 15min. The highest methane conversion was obtained when 5wt% Ru/TiO₂ catalysts were used after calcination at 400°C. The selectivities of light alkanes (C₂H₆, C₃H₈, C₄H₁₀) were highly increased when Ru/TiO₂ catalysts were used in DBD reactor.

Keywords: Plasma catalytic reaction; Methane conversion; Dielectric-barrier discharge; Ru/TiO; ₂; catalyst

Amberlyst A-21^®: An efficient, cost-effective and recyclable catalyst for the synthesis of substituted 4 H-chromenes by J.S. Yadav; B.V. Subba Reddy; Manoj K. Gupta; I. Prathap; S.K. Pandey (pp. 2208-2211).

A variety of substituted 4 H-chromene derivatives have been synthesized in good to excellent yields from o-hydroxybenzaldehydes and ethyl cyanoacetate or malononitrile in ethanol using inexpensive and reusable catalyst i.e., Amberlyst A-21^® under mild reaction conditions. The recovered activated catalyst is recycled in five times subsequent runs with no decrease in activity. The use of reusable catalyst makes this procedure quite simple, more convenient, economically viable and environmentally friendly.

Keywords: o; -Hydroxybenzaldehyde; Heterogeneous catalysis; Ethyl cyanoacetate; Chromenes

Ultrasound-assisted preparation of a novel Ni–B amorphous catalyst in uniform nanoparticles for p-chloronitrobenzene hydrogenation by Hui Li; Jing Zhang; Hexing Li (pp. 2212-2216).

Uniform Ni–B amorphous alloy nanoparticles were prepared by ultrasound-assisted reduction ofNi(NH3)62+ withBH4- in aqueous solution and the particle size was controlled by adjusting the ultrasound power. During liquid-phase p-chloronitrobenzene hydrogenation, the as-prepared Ni–B catalyst exhibited much higher activity and better p-chloroaniline selectivity than the regular Ni–B obtained via direct reduction of Ni²⁺ withBH4-. The higher activity could be attributed to both higher dispersion of Ni active sites and higher intrinsic activity. The higher selectivity could be attributed to both uniform Ni–B particles with larger size and Ni active sites with higher electron density.

Keywords: Ultrasound-assisted reduction; Ni–B amorphous alloy catalyst; Uniform diameter; p; -Chloronitrobenzene; Hydrogenation; p; -Chloroaniline

Synthesis of β-amino carbonyl compounds via a Mannich reaction catalyzed by SalenZn complex by Mei Wu; Huanwang Jing; Tao Chang (pp. 2217-2221).

A practical method was developed to synthesize a series of new β-amino carbonyl compounds via a three-component Mannich reaction of aromatic amines with aromatic aldehydes and active methylene compounds catalyzed by SalenZn complex under mild reaction condition. The catalyst and solvent effects were investigated. The substituted group effects of aromatic amines and aldehydes were also discussed.

Keywords: SalenZn complex; Mannich reaction; β-Amino carbonyl compounds; Aromatic amines; Aromatic aldehydes

Direct formation of H₂O₂ from H₂ and O₂ and decomposition/hydrogenation of H₂O₂ in aqueous acidic reaction medium over halide-containing Pd/SiO₂ catalytic system by Chanchal Samanta; Vasant R. Choudhary (pp. 2222-2228).

Formation of H₂O₂ from H₂ and O₂ and decomposition/hydrogenation of H₂O₂ have been studied in aqueous acidic medium over Pd/SiO₂ catalyst in presence of different halide ions (viz. F⁻, Cl⁻ and Br⁻). The halide ions were introduced in the catalytic system via incorporating them in the catalyst or by adding into the reaction medium. The nature of the halide ions present in the catalytic system showed profound influence on the H₂O₂ formation selectivity in the H₂ to H₂O₂ oxidation over the catalyst. The H₂O₂ destruction via catalytic decomposition and by hydrogenation (in presence of hydrogen) was also found to be strongly dependent upon the nature of the halide ions present in the catalytic system. Among the different halides, Br⁻ was found to selectivity promote the conversion of H₂ to H₂O₂ by significantly reducing the H₂O₂ decomposition and hydrogenation over the catalyst. The other halides, on the other hand, showed a negative influence on the H₂O₂ formation by promoting the H₂ combustion to water and/or by increasing the rate of decomposition/hydrogenation of H₂O₂ over the catalyst. An optimum concentration of Br⁻ ions in the reaction medium or in the catalyst was found to be crucial for obtaining the higher H₂O₂ yield in the direct synthesis.

Keywords: Direct H; ₂; O; ₂; formation; Pd/SiO; ₂; catalyst; H; ₂; O; ₂; decomposition; Br; ⁻; catalyst promoter

Wet 2,4,6-trichloro[1,3,5]triazine (TCT) an efficient catalyst for synthesis ofα,α′-bis(substituted-benzylidene) cycloalkanones under solvent-free conditions by Mohammad A. Bigdeli; Gholam Hossein Mahdavinia; Saeed Jafari; Hassan Hazarkhani (pp. 2229-2231).

An array of aromatic aldehydes undergo crossed aldol condensation with ketones in the presence of catalytic amounts of wet-TCT under solvent-free conditions to afford the correspondingα,α′-bis(substituted-benzylidene) cycloalkanones in excellent yields. Contrary to the existing methods, which use classical Lewis acids a new catalyst (TCT) is employed. This method is also general with respect to all types of aromatic aldehydes and is an eco friendly procedure.

Keywords: α; ,; α; ′; -bis(substituted-benzylidene) cycloalkanones; Crossed aldol condensation; Cyanuric chloride; Solvent-free

Solution synthesis of unsupported Ni–W–S hydrotreating catalysts by Le Zhang; Pavel Afanasiev; Dadong Li; Xiangyun Long; Michel Vrinat (pp. 2232-2237).

Solution synthesis of unsupported Ni–W–S hydrotreating catalysts was studied, in whichWO2S22- core reacted with Ni²⁺ ions, eventually in the presence of organic surfactant. The products were characterized by X-ray powder diffraction, low-temperature nitrogen adsorption, transmission electron microscopy and extended X-ray absorption fine structure spectroscopy. Catalytic activity of Ni–W–S systems was evaluated in thiophene hydrodesulfurization (HDS) reaction. It has been shown that highly active unsupported sulfides can be obtained by this method. The influence of preparation conditions on the activity and physico-chemical properties of the solids was discussed.

Keywords: Nickel; Tungsten; Unsupported catalyst; Hydrotreating; Thiosalt; EXAFS

Catalytic properties of Ru- η⁶-C₆H₆-diphosphine complexes for hydrogenation of benzene in aqueous-organic biphasic system by Li Zhang; Lei Wang; Xiao-Yan Ma; Rui-Xiang Li; Xian-Jun Li (pp. 2238-2242).

The influences of pH on the catalytic properties of Ru- η⁶-C₆H₆-diphosphine complex [RuCl( η⁶-C₆H₆)(BISBI)]Cl (1) (BISBI=2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl), [RuCl( η⁶-C₆H₆)(BDPX)]Cl (2) (BDPX=1,2-bis(diphenylphosphinomethyl)benzene), Ru₂Cl₄( η⁶-C₆H₆)₂( μ₂-BDNA) (3) (BDNA=1,8-bis(diphenylphosphinomethyl)naphthalene), [RuCl( η⁶-C₆H₆)(BISBI)]BF₄ (4), [RuCl( η⁶-C₆H₆)(BDPX)]BF₄ (5), and [( η⁶-C₆H₆)₂Ru₂Cl₂( μ₂-Cl)( μ₂-BDNA)]BF₄ (6) for the hydrogenation of benzene were investigated in aqueous-organic biphasic system. The hydrogenation of benzene catalyzed by all complexes yielded only cyclohexane. The catalytic results revealed that the stabilities of these complexes were not only closely relative with their compositions or molecular structures but also the pH value of aqueous solution. Complexes1 and2 were homogeneous catalysts at pH <5, but complexes3,4,5 and6 were partly decomposed in the same reaction conditions and played simultaneously the roles of homogeneous and heterogeneous catalysts. When the pH was up to 12, all of six complexes were gradually decomposed to Ru(0) particles. The addition of extra phosphine ligand was favorable to prevent these complexes from decomposing in the catalytic process. The experiment of mercury poisoning and the curve of conversion vs time strongly supported above conclusions.

Keywords: Biphasic catalysis; Ruthenium; Bidentate phosphine; Benzene; Hydrogenation

Selective catalytic reduction of NO_x with methane over indium supported on tungstated zirconia by Dong Yang; Junhua Li; Mingfen Wen; Chongli Song (pp. 2243-2247).

Selective catalytic reduction (SCR) of NO_x with methane was investigated over a series of non-noble metal (cobalt, manganese, nickel, tin, silver, indium) catalysts supported on tungstated zirconia (WZr). A great improvement of catalytic activity was found over the indium-loaded WZr catalysts upon the other WZr. The highest NO_x conversion of 70% was achieved over an 1%In/WZr catalyst at 450°C and 12,000h⁻¹. InO⁺ was proposed to be the active site in NO reduction. H₂O and SO₂ significantly inhibited NO reduction by competing with reactants to adsorb on InO⁺ site and forming inactiveIn(OH)2+ and In(SO₃)⁺ species.

Keywords: Nitrogen oxides; Selective catalytic reduction; Methane; Indium; Tungstated zirconia

Direct observation of induction period of MTO process with consecutive pulse reaction system by Yingxu Wei; Dazhi Zhang; Fuxiang Chang; Zhongmin Liu (pp. 2248-2252).

The initial transformation of methanol over HZSM-5 catalyst was investigated by a consecutive pulse reaction system. The reactant–catalyst contact time influenced the initial methanol transformation and the performances implied methanol reaction in induction period or under steady-state condition. The induction period, in which an organic-free HZSM-5 catalyst could be transferred to a working catalyst, were directly observed. The analysis result of the product stream predicted hydrogen-deficient species deposition over catalyst surface at the beginning of MTO reaction. The hydrogen transfer level of steady-state MTO reaction also varied with reaction contact time.

Keywords: MTO; Pulse reaction; Contact time; Induction period

Catalysts based on foam materials for neutralization of waste gases by A.N. Pestryakov; V.V. Lunin; V.P. Petranovskii (pp. 2253-2256).

Catalysts of new structural type – foam metals – have been tested in the process of complete oxidation of aromatic compounds and neutralization of gas emissions of furnaces for wire enameling. Foam catalysts have better hydrodynamic and mechanical characteristics as compared with commercial catalysts, high catalytic activity and life time in the processes of neutralization of waste gases exceeding the indices of the traditional granular and honeycomb catalysts.

Keywords: Foam catalysts; Deep oxidation

On the effect of La–Cr–O– phase composition on diesel soot catalytic combustion by S. Ifrah; A. Kaddouri; P. Gelin; G. Bergeret (pp. 2257-2262).

A series of samples of La–Cr–O– perovskites were designed as catalysts for diesel soot combustion. They were prepared by using co-precipitation method, at ambient temperature using ammonia followed by a hydrothermal treatment ( T=200°C, P=20atm, t=24h). All the chromium-containing precursors were then calcined at high temperature to develop the oxide catalyst. Two phase composition 86%LaCrO₃–(14%) La₂CrO₆ or 94%LaCrO₃–6%La₂O₃ were formed depending on the atmosphere of calcination (oxygen or hydrogen respectively) used. Their respective BET surface areas were 1.1 and 6.5m²g⁻¹. Highly crystalline, pure phase of LaCrO₃ and La₂CrO₆ powders were also prepared, with BET area of 4 and 3m²g⁻¹, respectively. The crystalline structure and properties of all samples were characterised by X-ray diffraction (XRD), using Rietveld refinement, and temperature-programmed reduction (TPR) techniques. O₂-TPD measurements performed on all samples showed the presence of suprafacial, weakly chemisorbed oxygen only for LaCrO₃, which contributes actively to soot combustion. TPR study performed on all catalysts showed that while pure LaCrO₃ and La₂O₃ samples did not reduce, the biphasic catalysts showed the presence of oxygen depletion peaks characteristic of lattice oxygen mobility in the samples at ca. 665°C. Catalytic combustion of diesel soot was studied over all catalysts. The results showed that pure LaCrO₃ exhibited significant catalytic activity which was sensitively affected by the modifier La₂CrO₆ or La₂O₃.

Keywords: Hydrothermal; La–Cr–O– phase composition; Reduction properties; Soot combustion

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Catalysis Communications (v.8, #12)

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Catalysis Communications (v.8, #12)