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Applied Catalysis A, General (v.455, #)

Contents (pp. iii-x).

Editorial Board (pp. co2).

Effective synthesis of cis-3-hexen-1-yl acetate via transesterification over KOH/γ-Al₂O₃: Structure and catalytic performance by Xiaoshuan Li; Dinghua Yu; Wengui Zhang; Zhengwen Li; Xiaowei Zhang; He Huang (pp. 1-7).

Display Omitted► Synthesis of cis-3-hexen-1-yl acetate via transesterification catalyzed by KOH/γ-Al₂O₃. ► Cis-3-hexen-1-yl acetate was synthetized at a low temperature (88°C). ► The K₂O·CO₂ species were main active compounds on the surface of KOH/γ-Al₂O₃. ► The catalyst only containing Al–O–K groups without K₂O·CO₂ species was inactive for transesterification.Cis-3-hexen-1-yl acetate is a significant green note flavor compound and widely used in the food and cosmetic industry. In this research, a series of solid base KOH/γ-Al₂O₃ have been prepared and been utilized for the synthesis of cis-3-hexen-1-yl acetate via transesterification from cis-3-hexen-1-yl and ethyl acetate. The catalysts were also characterized by several physic-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, N₂ adsorption, CO₂-temperature-programmed desorption (CO₂-TPD), and X-ray fluorescence (XRF). 30%KOH/Al₂O₃ was suggested to be the best conversion due to the cis-3-hexen-1-ol conversion of 59.3% at a temperature 88°C within 2h. Characterization results showed that KOH transformed into Al–O–K and K₂O·CO₂ species during the calcination process. It was confirmed that K₂O·CO₂ disappeared and Al–O–K groups existed on the surface of the water-washing 30%KOH/Al₂O₃ which was inactive for transesterification. K₂O·CO₂ species might be the major active species on KOH/Al₂O₃, and Al–O–K groups was inactive for cis-3-hexen-yl acetate synthesis.

Keywords: Cis-3-hexen-1-yl acetate; Cis-3-hexen-1-ol; Transesterification; KOH/γ-Al; ₂; O; ₃; Flavor

The effect of water on the hydrogenation of o-chloronitrobenzene in ethanol, n-heptane and compressed carbon dioxide by Haiyang Cheng; Xiangchun Meng; Yancun Yu; Fengyu Zhao (pp. 8-15).

Display Omitted► Water addition remarkably affected the reaction rate through hydrogen bonding. ► The improved activity is related to the phase behavior and interaction of CO₂ and reactants. ► The maximum conversion showed at 9MPa is about 2–4 times higher than that obtained without CO₂. ► The H₂O–CO₂ media and Pt/C catalyst is the most effective catalytic system.Water as a clean solvent and promoter in the organic synthesis have attracted more attention, herein the effect of water was studied for the hydrogenation of o-chloronitrobenzene ( o-CNB) over Pt/C and Pd/C catalysts in ethanol, n-heptane and compressed CO₂. Very interesting, the reaction rate decreased in ethanol, but increased in n-heptane and compressed CO₂ with the addition of water. The role of water in the reaction was mainly discussed from the experimental data and phase behavior analysis, one is to activate the functional group of NO₂ through the interactions via a hydrogen bonding, and the other is to affect the solubility of hydrogen in ethanol and n-heptane. The positive effect of the interaction between water and reactants may be counteracted by the negative effect of hydrogen solubility in ethanol. However, the concentration of o-CNB and hydrogen changed slightly in n-heptane with the addition of water, so the interaction of water with reactants may play a main role in improving the TOF. The combination of H₂O and CO₂ is more efficient than the pure H₂O, CO₂ and H₂O– n-heptane systems. The phase behavior may play important role also for the improved activity except for the interactions of H₂O and CO₂ with the reactants. o-CNB phase was expanded in the compressed CO₂ and so the concentration of H₂ in o-CNB phase increased due to the miscible of CO₂ and H₂, resulting in the enhancement of reaction rate and the maximum conversion at pressure of 9MPa CO₂, at which the volume was expanded to the largest one. The similar results were also obtained in the compressed CO₂ system without H₂O. In addition, the stability of Pt/C and Pd/C was studied in H₂O– n-heptane and H₂O–CO₂. As a result, the H₂O–CO₂ media and Pt/C catalyst is one of the most effective systems for the hydrogenation of o-CNB.

Keywords: o; -chloronitrobenzene; Hydrogenation; Water; Compressed carbon dioxide

Studies on the regeneration of sulfur-poisoned NO_X storage and reduction catalysts, including a Ba composite oxide by Toshiyuki Tanaka; Kumi Amano; Kazuhiko Dohmae; Naoki Takahashi; Hirofumi Shinjoh (pp. 16-24).

Display Omitted► Inhibition of sulfur re-adsorption under a rich condition improves NSR catalyst. ► Combination of Ba and Ti is effective for the inhibition of rich sulfur poisoning. ► The Ba-Ti composite oxide is more effective for a prevention of sulfur deactivation.The analysis of sulfur deterioration and regeneration of a NO_X storage and reduction (NSR) catalyst containing Ba as the storage material and TiO₂ as the support was conducted. It was found that the inhibition of sulfur re-adsorption during the sulfur desorption procedure under a rich atmosphere is important for improving sulfur desorption from a sulfur poisoned NSR catalyst, and that the combination of a Ba compound and a TiO₂ support is effective for the inhibition of sulfur poisoning under both lean and rich conditions. On the basis of these results, a highly dispersed Ba-Ti composite oxide catalyst was prepared using a Ba-Ti complex precursor in order to realize the nm-scale distribution of Ba and Ti. Furthermore, it was concluded that the principal factor contributing to the high performance of the Ba-Ti catalyst in terms of the sulfur desorption rate was its ability to inhibit repetitive adsorption during rich treatment for sulfur desorption.

Keywords: NSR catalyst; Desulfation; Barium sulfate; Titanium oxide; Citric acid

Hybrid photocatalytic water splitting for an expanded range of the solar spectrum with cadmium sulfide and zinc sulfide catalysts by E. Baniasadi; I. Dincer; G.F. Naterer (pp. 25-31).

Display Omitted► We developed a new photo-catalytic and electro-catalytic water splitting systems. ► Hybridization of the photo-catalytic process is examined with multi catalysts. ► Different light intensities and photo-catalyst concentrations are examined. ► CdS shows higher energy and exergy efficiencies compared with ZnS photo-catalysts. ► The hydrogen production of 0.41mmolh⁻¹ with 3% (w/v) ZnS is improved by almost 2 times due to hybridization.In this paper, an experimental study of photo-catalytic water splitting with cadmium sulfide and zinc sulfide photo-catalysts is performed in a dual-cell reactor to investigate the effects of radiation intensity and photo-catalyst concentration on hydrogen and oxygen production rates. Hybridization of the photo-catalytic process is examined with multi catalysts and electric potential bias to enhance the productivity of the reactor and sustain the reaction rate. The hydrogen production of 0.41mmolh⁻¹ with 0.75% (v/v) ZnS is improved by almost 2 times higher than past studies due to illumination of 0.2% (v/v) CdS under 1 sun in a hybrid reactor. The productivity of the reactor is significantly enhanced at light intensities more than 1000Wm⁻². The cadmium sulfide catalyst is found to be an inefficient absorbent of light energy, but it shows higher energy and exergy efficiencies compared with ZnS photo-catalysts in a light-driven water splitting process.

Keywords: Abbreviations; HER; hydrogen evolving reaction; HHV; higher heating value (kJ; mol; ⁻¹; ); NHE; normal hydrogen electrode; OER; oxygen evolving reaction; UV; ultravioletHydrogen production; Solar energy; Photo-catalysis; Efficiency; Hybridization

Selective photoreduction of CO₂ to CO in CO₂-dissolved expanded liquid phase with heterogeneous CO₂-philic Pd complex catalysts by R. Liu; H. Yoshida; S. Fujita; N. Lu; W.H. Tu; M. Arai (pp. 32-38).

Display Omitted► Fluorinated Pd complexes are immobilized on the surface of fluorinated SiO₂ support. ► The Pd catalysts are active for photoreduction of CO₂ to CO in CO₂ expanded liquids. ► The catalytic activities change depending on CO₂ pressure and organic solvent used. ► The immobilized Pd complexes show the highest activity and 100% selectivity to CO.Novel CO₂-philic Pd complexes, PdCl₂[4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy] (bpy: 2,2′-bipyridine) where R_f= n-C₁₀F₂₁, n-C₁₁F₂₃, were anchored onto a silica support modified with long fluorinated hydrocarbon chains (C₆F₁₃) by mixing these complex and the support in DMSO at 413K. These immobilized Pd complex catalysts were applied for the photoreduction of CO₂ in DMF or organic solvents using triethylamine as a hydrogen donor at 323K. The rate of CO₂ reduction and the selectivity to CO were observed to depend on several factors including CO₂ pressure, solvent, Pd complex structure, and Pd loading. With the most active catalyst, the selective photoreduction of CO₂ to CO can be achieved in DMF at a CO₂ pressure of 4MPa and the performance observed is much better compared to the literature results. The features of the supported Pd complexes and the multiphase reaction media were characterized by UV–vis absorption and others to discuss the reasons for their high performance.

Keywords: Heterogeneous catalysis; Palladium; Reduction; Catalyst design; Photocatalysis; Expanded liquid

Copper nanoparticles supported on silica coated maghemite as versatile, magnetically recoverable and reusable catalyst for alkyne coupling and cycloaddition reactions by F. Nador; M.A. Volpe; F. Alonso; A. Feldhoff; A. Kirschning; G. Radivoy (pp. 39-45).

.Display Omitted► Copper nanoparticles on nanosized magnetic support as catalyst for alkyne synthetic transformations. ► Commercially available silica coated maghemite (MagSilica) is used as magnetic support. ► The nanocatalyst is easily recovered and reused by means of an external magnet. ► High versatility of the catalyst for high atom economy alkyne coupling and cycloaddition reactions.A versatile and magnetically recoverable catalyst consisting of copper nanoparticles on silica coated maghemite nanoparticles (MagSilica^®) is presented. The catalyst has been prepared under mild conditions by fast reduction of anhydrous CuCl₂ with lithium sand and a catalytic amount of DTBB (4,4’-di- tert-butylbiphenyl) as electron carrier, in the presence of the magnetic support. The catalyst has been fully characterized and its performance in different coupling and cycloaddition reactions of terminal alkynes has been studied. This new copper-based catalyst has shown to be very efficient and easily reusable in the Glaser alkyne dimerization reaction in THF, the multicomponent Huisgen 1,3-dipolar cycloaddition reaction in water and the three-component synthesis of propargylamines under solvent free conditions.

Keywords: Copper nanoparticles; Magnetic support; Alkyne; Coupling; Cycloaddition

High-performance ring-opening catalysts based on iridium-containing zeolite Beta in the hydroconversion of decalin by Dominic Santi; Tobias Holl; Vincenzo Calemma; Jens Weitkamp (pp. 46-57).

Display Omitted► Open-chain decanes were made from decalin with unprecedented yields up to 44%. ► The acid strength of the Ir/Beta catalyst was tuned by exchange with alkali cations. ► The term high-performance ring-opening catalysts (HIPEROCs) was introduced. ► The main mechanism of ring opening on HIPEROCs is hydrogenolysis on the metal. ► A detailed reaction scheme was advanced for selective ring opening on HIPEROCs.Decalin was converted in a flow-type reactor under a hydrogen pressure of 5.2MPa on Ir/H,A-Beta zeolite catalysts, where A stands for an alkali metal cation. In one series of catalysts, the Ir content was 3wt.%, and the nature of A was varied from lithium to cesium. In a second series, the iridium content in Ir/H,Cs-Beta was varied from 1 to 5wt.%. On some of these catalysts, open-chain decanes (OCDs) were formed with unprecedented selectivities and yields of up to 47 and 44%, respectively. The term “High-Performance Ring-Opening Catalysts” (HIPEROCs) was defined. Evidence is presented for hydrogenolysis on the metal being the main ring-opening mechanism on HIPEROCs. The main function of the Brønsted-acid sites is a mild isomerization of six-membered into five-membered naphthenic rings which are much easier to open by hydrogenolysis. Valuable mechanistic information can be deduced from the carbon-number distributions and the naphthenes vs. alkanes content of the hydrocracked products (C₉-).

Keywords: Selective ring opening; Open-chain decanes; Ir/Beta; HIPEROCs; Bifunctional catalysis; Hydrogenolysis; Decalin

A novel synthetic approach for preparing dimethyl carbonate from dimethoxymethane and O₂ over Cu-MCM-48 by Yongjie Ding; Aiguo Kong; Hengqiang Zhang; Huanhuan Shen; Zhuodong Sun; Songping D. Huang; Yongkui Shan (pp. 58-64).

Display Omitted► A new catalytic synthesis process for dimethyl carbonate. ► Very high dimethyl carbonate yield (81.8%). ► Short reaction time and the recycled Cu-MCM48 catalyst.A new convenient method for the synthesis of dimethyl carbonate from dimethoxymethane and O₂ in the presence of catalytic amounts of Cu-MCM-48 was described. The XRD results indicate that the structure of Cu-MCM-48 is gradually distorted with the increase in the copper content, whereas the framework structure of Cu-MCM-48 is basically retained until the incorporated copper content reaches to 0.62wt%. The SEM, TEM and N₂ adsorption studies show that copper content of 9.51wt% completely changes the morphology and structure of Cu-MCM-48. Effects of the amount of the incorporated copper in catalyst, catalyst amount used and other reaction conditions on the catalytic activity are investigated in details to obtain the optimized reaction conditions. Short reaction time, easy recycling of the catalyst and excellent yields are the main advantages of this process.

Keywords: Dimethyl carbonate; Dimethoxymethane; Molecular oxygen; Cu-MCM-48

Theoretical study on the cracking reaction catalyzed by a solid acid with zeolitic structure: The catalytic cracking of 1-hexene on the surface of H-ZSM-5 by Yu-Hua Guo; Min Pu; Biao-Hua Chen; Feng Cao (pp. 65-70).

Display Omitted► The H-ZSM-5 zeolite is found to have high activity and selectivity in light olefin cracking reactions. ► The cracking mechanism of hexene over H-ZSM-5 zeolite is investigated by using ONIOM method. ► The olefin cracking process follows a two-step mechanism involving a carbenium ion intermediate. ► The H-ZSM-5 zeolite environment plays a significant role in stabilizing the hexyl carbenium ion. ► The extended zeolite framework also has profound effects on the energetics of the system.The cracking mechanism of 1-hexene over H-ZSM-5 zeolite has been studied by using the ONIOM(B3LYP/6-31G(d,p):UFF) method with an 88T cluster model and the B3LYP/6-31G(d,p) method with a 5T cluster model. The computation results show that the cracking process follows a two-step mechanism involving a carbenium ion intermediate. When the 88T cluster model is used, a stable carbenium ion can be found. When the 5T cluster model is used, no stable carbenium ion is obtained, however, the intrinsic reaction coordinate prompts that there exists a carbenium ion intermediate during the reaction process. The theoretical researches indicate that the H-ZSM-5 zeolite environment plays a significant role in stabilizing the hexyl carbenium ion. The adsorbed carbenium ion on the surface of zeolite is an active high energetic species, and the cleavage of the CC bond on β position occurs easily. The extended zeolite framework has a large effect on the energetics of the adsorbed complexes. The apparent energy barrier of the cracking reaction with 88T cluster model is 104.73kJ/mol and that with 5T cluster model is 149.50kJ/mol.

Keywords: Zeolite; H-ZSM-5; Catalysis; Hexene; Cracking; ONIOM

Catalytic potential of the wonderful chameleons: Nickel phosphate molecular sieves by M.N. Timofeeva; V.N. Panchenko; Zubair Hasan; Sung Hwa Jhung (pp. 71-85).

Display Omitted► Effect of compositions on structural and physicochemical properties of VSB- n was analyzed. ► Adjustable capability of acid–base and red-ox properties of VSB- n was emphasized. ► Opportunities and challenges involved in catalytic applications of VSB- n are reported.This review is devoted to the discoveries and knowledge developed in the past 10–15 years in the area of the design and applications of nickel phosphate molecular sieves (VSB-1 and VSB-5). The main textural and physicochemical characteristics of these materials that make them suitable for catalysis were viewed at the molecular and atomic levels. According to various spectroscopic investigations, the type of metal ions introduced into the VSB-1 and VSB-5 framework allows one to adjust the nature of the surface functional groups and thereby, affects the catalytic properties. Emphasis is placed upon the relationship between the physicochemical properties and their catalytic properties in hydrogenation, oxidation and acid–base type reactions. Because of the simultaneous existence of acid–base and red-ox pairs, nickel phosphate molecular sieves, similar to a chameleon, can adapt to catalytic systems and provide necessary active sites. This review clearly demonstrates that nickel phosphate molecular sieves (VSB- n series) possess promising catalytic properties: e.g., shape selectivity, red-ox and acid–base catalysis, and we expect that this work opens the door to novel applications of these materials in catalysis.

Keywords: Nickel phosphate molecular sieves; VSB-1; VSB-5; Acid–base; Red-ox; Catalytic properties; Review

Characterization and photocatalytic activity of nitrogen-doped titanium(IV) oxide prepared by doping titania with TiN powder by Motoki Iwase; Keiji Yamada; Tsutomu Kurisaki; Hisanobu Wakita (pp. 86-91).

Display Omitted► Nitrogen-doped TiO₂ (N-TiO₂) was prepared by doping TiO₂ with TiN powder. ► We succeeded to prepare anatase N-TiO₂ using a small amount of TiN powder. ► The N atom dopants inhibited the phase transformation from anatase to rutile. ► The XPS N1s spectra of N-TiO₂ differed from those of simply oxidized TiN particles.Titanium(IV) oxide (TiO₂) was doped with a small amount of TiN powder to obtain anatase nitrogen-doped TiO₂(N-TiO₂) with visible-light activity because the oxidation of TiN powder generally led to the formation of rutile N-doped TiO₂. The synthesized N-TiO₂ was yellow, and its UV–vis spectrum of N-TiO₂ showed a continuous and tailing absorption in the visible region. The properties of N-TiO₂ were compared with those of pureTiO₂ and oxidized TiN particles. XRD patterns revealed that the ratio of the rutile phase to the anatase phase in N-TiO₂ was lower than that in pure TiO₂. These results indicate that the N atom dopants inhibit the phase transformation from anatase to rutile. The XRD patterns for all oxidized TiN particles showed the presence of the rutile phase. The results indicate that the TiO₂ rutile phase is more likely to be formed by the heat treatment of TiN particles. The lack of phenol degradation in the presence of ST01 under visible light (423–600nm) irradiation indicated that the TiO₂ anatase phase was inactive to visible light. On the other hand, a decrease in the phenol content for N-TiO₂ calcined at 600°C (N-TiO₂(600)), which was almost completely in the anatase form, revealed that N-doped anatase moieties responded favorably to visible light. The degradation amount for TiN particles oxidized at 600°C (TiN(600)) was comparable to that for N-TiO₂(600) in spite of the fact that the nitrogen content of TiN(600) was larger than that of N-TiO₂(600) (N/Ti=1.0 vs. N/Ti=0.10, respectively). The low degradation amount of TiN(600) was most likely due to the low fraction of the anatase phase and the presence of the cubic TiN phase. N-TiO₂ prepared using a small addition of TiN particles showed visible-light activity originating from the anatase N-doped moieties.

Keywords: Nitrogen-doped TiO; ₂; TiN; Titania; Photocatalysis; Visible light

Transesterification of triacetin and castor oil with methanol catalyzed by supported polyaniline-sulfate. A role of polymer morphology by A. Drelinkiewicz; Z. Kalemba-Jaje; E. Lalik; A. Zięba; D. Mucha; E.N. Konyushenko; J. Stejskal (pp. 92-106).

Display Omitted► Transesterification of triacetin and castor oil with methanol. ► Esterification of ricinoleic acid with methanol. ► Polyaniline sulfate-based catalysts. ► Multi wall carbon nanutubes coated with polyaniline sulfate. ► Blockage of catalysts in methanolysis of triacetin.Polyaniline-sulfate deposited on three different carriers was studied for transesterification of triacetin and castor oil with methanol at mild reaction conditions (temperature of 55°C). Multi-wall carbon nanotubes (CNT), carbon and silica were coated with polyaniline sulfate (ca. 20wt%) during polymerization of aniline. Because of different textural and hydrophobic properties of the carriers, the polymer coatings of various morphologies were obtained as evidenced by the electron microscopy technique. A uniform coating of CNT with polymer resulted in the most extended polymer structure. Nanorods of polymer forming branched dendritic structures appeared in the other two carbon and silica carriers. The acid capacity and the strength of acid sites were similar in all studied catalysts. All the samples were found to be active solid acid catalysts in methanolysis of both studied triglycerides and CNT-coated polyaniline sulfate exhibited the highest activity. The course of reaction during methanolysis of triacetin on CNT-containing catalyst was similar to that in the presence of soluble sulfuric acid. On the other hand, a partial blockage of active sites was observed in carbon and silica coated with polyaniline sulfate. A blockage effect was ascribed to strong interaction of acid sites with more polar reagents among them diacetin and glycerol. These interactions were facilitated by aggregated fibriral morphology of the polymer coating resulting in locally high density of acid sites.

Keywords: Transesterification; Triacetin; Castor oil; Polyaniline

Selective skeletal isomerization of 1-butene over FER-type zeolites derived from PLS-3 lamellar precursors by Boting Yang; Jin-gang Jiang; Hao Xu; Yuming Liu; Honggen Peng; Peng Wu (pp. 107-113).

Display Omitted► Al-PLS-3 zeolites with the FER topology are derived from lamellar precursors. ► Al-PLS-3 zeolites possess a relatively small crystal size of 50–150nm. ► Al-PLS-3 zeolites have a tunable Si/Al ratio of 40–∞. ► Al-PLS-3 serves as an active and selective catalyst in the 1-butene skeletal isomerization. ► Al-PLS-3 proves to be more durable than commercial ferrierite catalyst.Layered aluminosilicates of PLS-3 were hydrothermally synthesized and employed as the catalysts for the skeletal isomerization of 1-butene. PLS-3 lamellar precursors were successfully prepared at different Si/Al ratios (40–∞) using layered silicate H-kanemite as silica source and tetramethylammonium hydroxide as structure directing agent. A direct calcination caused an interlayer dehydration condensation, converting the precursors into 3-dimensional FER structure with an intersecting micropore system of 8×10-membered rings. The physicochemical properties of the Al-PLS-3 materials thus prepared were characterized by various techniques. Their catalytic properties in the skeletal isomerization of 1-butene has been investigated and compared with conventional ferrierite. Al-PLS-3 synthesized at Si/Al=50 exhibited the same catalytic reactivity as commercial ferrierite. However, possessing smaller crystal size, Al-PLS-3 possessed a much longer catalytic duration against coke formation.

Keywords: Lamellar zeolites; PLS-3; FER; Hydrothermal synthesis; 1-Butene isomerization

Improving the aromatic production in catalytic fast pyrolysis of cellulose by co-feeding low-density polyethylene by Xiangyu Li; Haifeng Zhang; Jian Li; Lu Su; Jiane Zuo; Sridhar Komarneni; Yujue Wang (pp. 114-121).

Display Omitted► Cellulose and LDPE have a synergy in catalytic fast pyrolysis with ZSM-5 zeolite. ► Co-feeding of LDPE with cellulose increases aromatic yield in catalytic pyrolysis. ► Co-feeding of LDPE with cellulose improves the monoaromatic selectivity. ► Co-feeding of LDPE with cellulose decreases coke yield in catalytic fast pyrolysis.Catalytic fast pyrolysis (CFP) of cellulose, low-density polyethylene (LDPE), and their mixture (1:1) with ZSM-5 zeolite was investigated to determine the interaction between cellulose and LDPE when they are co-fed in CFP. Results show that CFP of the cellulose and LDPE mixture produced a much higher aromatic carbon yield (47.46%) than CFP of cellulose (37.66%) and LDPE (34.29%) individually. CFP of the mixture also produced a higher aromatic selectivity for more valuable monoaromatics (85.1%) than CFP of cellulose alone (66.7%). Additionally, CFP of the mixture produced much less coke (11.94%) than CFP of cellulose (36.62%). Co-feeding of LDPE with cellulose can thus decrease the rate of catalyst deactivation by coke deposits that occur rapidly in CFP of cellulose. These results indicate that when cellulose and LDPE are co-pyrolyzed with ZSM-5 zeolite, they have a positive synergistic effect that improves aromatic production and decreases coke formation. Co-feeding of LDPE with cellulose thus has a beneficial effect on cellulose conversion in CFP.

Keywords: Biomass; Plastics; Pyrolysis; Zeolite; Aromatic hydrocarbon; Catalysis

Skeletal isomerization of tetradecane catalyzed by TON-type zeolites with a fragmented core–shell structure by Masaki Okamoto; Lili Huang; Midori Yamano; Sayuri Sawayama; Yohei Nishimura (pp. 122-128).

Display Omitted► TON-type zeolites with a core–shell structure were synthesized by crystal overgrowth. ► The core–shell zeolite with minimal defects was synthesized in the presence of F ion. ► The shell passivated acid sites on the external surface. ► Breaking the core–shell structure enhanced the catalytic activity and selectivity.TON-type zeolites with a core–shell structure were synthesized by crystal overgrowth of an aluminum-free TON-type zeolite on an aluminum-containing TON-type zeolite in the presence of fluoride ion, which was used as a mineralizing reagent to restrain the formation of defects. The core–shell structured zeolite showed greater selectivity for skeletal isomerization in tetradecane hydroisomerization because the acid sites on the external surface of needle-shaped crystals were passivated to inhibit cracking. Breaking the needle-shaped crystals of the core–shell structure to create shorter crystal pieces effectively enhanced the catalytic activity and selectivity for isomerization because new pore entrances were formed.

Keywords: Core–shell structure; Passivation; Isomerization; TON-type zeolite

CH₄–CO₂ reforming over Ni-substituted barium hexaaluminate catalysts by Todd H. Gardner; James J. Spivey; Edwin L. Kugler; Devendra Pakhare (pp. 129-136).

Display Omitted► The used catalyst shows contraction of the unit cell, the result of NiO reduction. ► Graphitic carbon is confirmed after catalyst use. ► Catalyst light-off temperature correlates with Ni substitution into the lattice. ► Carbon deposition on the used catalysts correlates with Ni substitution.A series of Ni-substituted barium hexaaluminate catalysts, Ba_0.75Ni_yAl12−_yO19−_δ ( y=0.4, 0.6 and 1.0), were tested for CO₂ reforming of CH₄ at temperatures between 200 and 900°C. Temperature programmed surface reaction results show that the reaction lights-off in a temperature range between 448 and 503°C with a consistent decrease in light-off temperature with increasing Ni substitution. Isothermal runs performed at 900°C show near equilibrium conversion and stable product concentrations for 18h on all catalysts. Temperature programmed oxidation of the used catalysts show that the amount of carbon deposited on the catalyst increases with Ni substitution. High resolution XRD of the used Ba_0.75Ni_0.4Al_11.6O19−_δ catalyst shows a statistically significant contraction of the unit cell which is the result of NiO reduction from the lattice. XRD of the used catalyst also confirms the presence of graphitic carbon. XPS and ICP measurements of the as prepared catalysts show that lower levels of Ni substitution result in an increasing proportion of Ba at the surface.

Keywords: Ni-substituted hexaaluminate; Methane dry reforming; Syngas; Carbon dioxide; Green house gas

Highly efficient Pd–ZnO catalyst doubly promoted by CNTs and Sc₂O₃ for methanol steam reforming by Lu Yang; Guo-Dong Lin; Hong-Bin Zhang (pp. 137-144).

Display Omitted► Highly efficient CNTs and Sc₂O₃ doubly promoted Pd–ZnO catalyst for MSR was developed. ► CNTs can act as a novel promoter of CH₃OH dehydrogenation by promoting H spillover. ► Sc₂O₃ can act as a modifier of Pd–ZnO catalyst by ion-doping and valence-compensation.A type of Pd–ZnO catalyst doubly promoted by CNTs and Sc₂O₃ for methanol steam reforming (MSR) was developed, and displayed excellent activity and operation stability for the selective formation of H₂ and CO₂. Over a Pd_0.15Zn₁Sc_0.067–10%CNTs catalyst under the reaction conditions of 0.5MPa and 548K, the STY(H₂) can maintain stable at the level of 1.56molh⁻¹g⁻¹ at 75h after the reaction started, which was 1.7 times that of the corresponding (CNTs and Sc)-free counterpart Pd_0.15Zn₁. Characterization of the catalyst revealed that the highly conductive CNTs could promote hydrogen spillover from the PdZn/ZnO-sites to the CNTs adsorption-sites, and then combine to form H₂(a), followed by desorbing to H₂(g), which would help increase the rate of a series of surface dehydrogenation reactions in the MSR process. The pronounced modification action of Sc³⁺ may be due to the high solubility of Sc₂O₃ in ZnO lattice. Solution of a small amount of Sc₂O₃ in ZnO lattice resulted in the formation of Schottky defects in the form of cationic vacancies at the surface of ZnO, where the (PdZn)⁰–Pd²⁺ clusters can be better stabilized through the Pd²⁺ accommodated at the surface vacant cation-sites. This would be conducive to inhibiting the sintering of the catalytically active (PdZn)⁰ nanoparticles, and thus, markedly prolonging the life of the catalyst.

Keywords: MWCNTs; Pd–ZnO catalyst; Sc; ₂; O; ₃; Methanol steam reforming

Investigation of K-promoted Cu-Zn-Al, Cu-X-Al and Cu-Zn-X (X=Cr, Mn) catalysts for carbon monoxide hydrogenation to higher alcohols by E. Heracleous; E.T. Liakakou; A.A. Lappas; A.A. Lemonidou (pp. 145-154).

Display Omitted► Higher alcohols were synthesized from syngas over modified K/Cu-Zn-Al catalysts. ► The synthesis yields primary 2-methyl branched alcohols with up to five carbons. ► Cr-substitution favors methanol formation and reduces alcohol chain homologation. ► Substitution of Zn by Mn leads to a 50% increase in HAS compared to the base case. ► Inverse correlation between acidity and higher alcohols selectivity was established.In this study, we report the effect of Cu/Zn/Al chemical composition and Zn and/or Al substitution by Mn and/or Cr in K-promoted Cu-Zn-Al catalysts for the hydrogenation of CO to higher alcohols. In terms of higher alcohols, the synthesis yielded preferentially primary 2-methyl branched alcohols with up to five carbon atoms, namely 2-methyl-1-propanol and 2-methyl-1-butanol, together with ethanol and propanol. Variation of the Cu/Zn/Al chemical composition showed that the catalyst with a Cu/Zn atomic ratio of 1 and low Al content (K-Cu₄₅Zn₄₅Al₁₀) exhibits the optimum performance in terms of both activity and selectivity to higher alcohols. High Al contents on the other hand favor methanol production at the expense of higher alcohols. It is postulated that due to its acidic nature, alumina reduces the basic sites on the catalyst, thereby retarding the C₁→C₂ step. Substitution of Zn and/or Al by Mn and/or Cr was found to reduce activity by ∼50%, probably due to the lower exposed copper surface area as indicated by the formation of larger CuO crystals. In terms of selectivity, the most appreciable changes were recorded for the K-Cu₄₅Mn₄₅Al₁₀ catalyst, where a 50% increase in higher alcohol formation was measured, rendering the catalyst the most selective among the investigated materials. Characterization of the catalysts provided some insight on the beneficial influence of Zn substitution by Mn in the K-Cu₄₅Mn₄₅Al₁₀ sample. Inverse correlation between acidity and higher alcohols selectivity was evidenced, in accordance with the general notion that higher alcohol formation requires basic sites and indicates that reduced acidity is needed for the aldol-type condensation reactions. The replacement of Mn by Zn in K-Cu-Mn-Al reduced acidity and thus promoted the production of the desired higher alcohol products.

Keywords: CO hydrogenation to higher alcohols; Cu-Zn-Al catalysts; Alkali promotion; Cr promoter; Mn promoter; Acidity

Metathesis of methyloleate over methyltrioxorhenium supported on ZnCl₂-promoted mesoporous alumina by Subha Kumaraswamy Pillai; Safia Hamoudi; Khaled Belkacemi (pp. 155-163).

Display Omitted► Highly active 3%MTO/ZnCl₂–Al₂O₃-meso catalyst for methyloleate self-metathesis. ► This catalyst reached high yield of 87% for total metathesis products. ► Al/Zn ratio of 8–12 was revealed optimum for methyoleate metathesis conversion. ► Other metal halides did not promote metathesis of methyloleate as zinc chloride.Methyltrioxorhenium impregnated on ZnCl₂-modified mesoporous alumina at Al/Zn ratio of 8–12 was revealed as an effective catalyst for self-metathesis of methyloleate at mild reaction conditions.The use of other promoters either in form of metal chlorides or as other zinc halides did not promote the metathesis of methyloleate as zinc chloride. The enhancement of the activity was not only due to the chloride and/or zinc but could be attributed to the interaction of both elements as Zn–Cl or ZnCl₂ bonds with the mesoporous alumina.The results of this research suggest that it is possible to design a heterogeneous catalyst for the efficient and selective self-metathesis of functionalized olefins such as methyloleate and edible oils, avoiding the utilization of expensive homogeneous catalysts or use of toxic promoters such as SnR₄ with heterogeneous catalysts.

Keywords: Self-metathesis; Methyloleate; Methyltrioxorhenium (MTO); ZnCl; ₂; -promoted mesoporous alumina

Synthesis of biolubricants using sulfated zirconia catalysts by Jinho Oh; Sungeun Yang; Chanyeon Kim; Inchang Choi; Jae Hyun Kim; Hyunjoo Lee (pp. 164-171).

Display Omitted► Sulfated zirconia catalysts were used for effective synthesis of biolubricants. ► Biolubricants consist of esters produced via esterication/transesterification. ► Soybean oil or its cleaved free fatty acids were used as biomass resource. ► In situ hydrogenation occurred without H₂ gas. ► Biolubricants showed improved viscosity index compared to commercial products.Synthesis of biomass-derived lubricants via esterification, transesterification, and simultaneous reactions of both was studied by using sulfated zirconia catalysts. Soybean oil or free fatty acids derived from soybean oil were used as a biomass-derived resource for the synthesis of biolubricants. Long chain alcohols (carbon number≥8) or neo-polyols (e.g., 2,2-diethyl-1,3-propanediol, trimethylol propane, pentaerythritol) were used as co-reactants. The structure of the alcohol significantly affected the conversion and yield for the esterification with oleic acid. The esters produced showed kinematic viscosity and viscosity index comparable to commercial lubricants. Various sulfated zirconia catalysts were prepared and were characterized by X-ray diffraction, NH₃ temperature-programmed desorption, Brunauer–Emmett–Teller isotherm, and tested for esterification. The type of zirconium precursor demonstrated a significant effect on the physical property of the catalyst and its catalytic activity. Interestingly, esters with fully saturated hydrocarbon chains were synthesized from unsaturated free fatty acids regardless of the absence of hydrogen gas. The sulfated zirconia could be recycled for up to five repeated reactions without any degradation. The effects of reaction time and temperature were also investigated.

Keywords: Biomass; Biolubricants; Transesterification; Esterification; Sulfated zirconia

Mo(II) complexes of 8-aminoquinoline and their immobilization in MCM-41 by Marta S. Saraiva; Carla D. Nunes; Teresa G. Nunes; Maria José Calhorda (pp. 172-182).

Display Omitted► Two new Mo(II) complexes with the 8-aminoquinoline ligand were prepared. ► The Mo(II) complexes were immobilized in MCM-41 using two different methodologies. ► MCM-Mo(II) materials were active pre-catalysts for olefin epoxidation. ► Homogeneous catalysts are more active than their heterogeneous counterparts. ► All catalysts epoxidize allylic alcohols selectively.Two new Mo(II) complexes [MoBr(η³-C₃H₅)(CO)₂(8-aq)] (1) and [MoI₂(CO)₃(8-aq)] (2) containing the bidentate 8-aminoquinoline ligand (8-aq) were synthesized and characterized. They were immobilized in MCM-41. A 3-iodopropyltrimethoxysilane spacer reacted both with the surface, through the silane, and through the other end, with the coordinated8-aq of complexes1 and2, leading to an immobilized form of the complex (MCM-Pr-1,2). In an alternative route, 8-aq reacted with 3-iodopropyltrimethoxysilane to form a new ligandL₁, which could be supported in the MCM-41 and then react with the metal precursors to afford (MCM-L₁-1,2). The complexes and the materials were characterized using FTIR and NMR spectroscopies, and the structure of the materials was checked with powder X-ray diffraction and nitrogen adsorption isotherms. The first synthetic procedure was less efficient in terms of metal load inside the channels of the materials.The complexes and the new materials were tested as catalytic precursors in the epoxidation of cis-cycloctene, styrene, 1-octene, R-(+)limonene, geraniol, cis-3-hexene-1-ol and trans-2-hexene-1-ol, using tert-butylhydroperoxide (TBHP) as oxidant. Although almost all the catalysts were 100% selective toward the epoxide, the conversions were in general poor. The best catalyst was complex1, but the conversions dropped after immobilization. Conversions could be a bit improved by a careful choice of reaction conditions, the most effective being the absence of added solvent (the substrate acted as solvent).

Keywords: Molybdenum; MCM; Oxidation catalysis; 8-Aminoquinoline; Alkenes

Facile microwave-assisted synthesis of monodispersed ball-like Ag@AgBr photocatalyst with high activity and durability by Xiang Xu; Xiaoping Shen; Hu Zhou; Dezhou Qiu; Guoxing Zhu; Kangmin Chen (pp. 183-192).

Display Omitted► The monodispersed and uniform Ag@AgBr ball-like photocatalysts were synthesized. ► The shape, size and composition of the products could be well controlled. ► The Ag@AgBr visible light photocatalysts show high activity and good durability. ► The degradation pathways and the mechanism of photocatalytic process were proposed.We reported a rapid one-step microwave-assisted approach to synthesize a plasmonic photocatalyst of ball-like AgBr nanoparticles ( ca. 290nm in average diameter) with a small amount of metal Ag anchored on the surface. The obtained Ag@AgBr nanocomposites were characterized by means of X-ray diffraction, scanning electron microscopy, Transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. The shape, size, and compositions of the Ag@AgBr photocatalysts could be controlled by tuning the microwave irradiation time and the concentrations of polyvinylpyrrolidone (PVP) in the reaction solution. The as-prepared Ag@AgBr plasmonic photocatalysts show excellent visible-light photocatalytic performance and good reusability for decomposing organic pollutant of Rhodamine B (RhB) due to the surface plasmon resonance (SPR) effect of Ag nanoparticles. Meanwhile, the possible degradation pathways of RhB and a mechanism of the plasmonic photocatalytic process were also proposed.

Keywords: Nanoparticles; Photocatalysis; Silver; Silver bromide; Microwave

Ethanol electro-oxidation using cadmium-doped cobalt/carbon nanoparticles as novel non precious electrocatalyst by Nasser A.M. Barakat; Mohammad A. Abdelkareem; Hak Yong Kim (pp. 193-198).

Display Omitted► The study introduces Co-mainly-based material as EOR electrocatalyst. ► Cd-doped Co nanoparticles encapsulated in graphite shell are introduced. ► The introduced NPs can be effectively used as electrocatalyst in ethanol oxidation. ► The introduced NPs reveal low onset potential and high current densities.Novel electrocatalyst based on non precious metals (Co and Cd) is introduced to be used as anode in the ethanol fuel cells. Cd-doped Cobalt nanoparticles encapsulated in graphite shell have been synthesized using simple sol–gel technique. The introduced electrocatalyst can be prepared from a sol–gel composed of cadmium acetate, cobalt acetate and poly(vinyl alcohol) based on the polycondensation possibility of the acetates. Grinding and calcination in Ar atmosphere of the prepared gel leads to produce Cd-doped Co nanoparticles encapsulated in a thin graphite layer. High current density (70mAcm⁻²) and considerably low onset potential (∼585mV vs. NHE) were obtained when the synthesized nanoparticles have been exploited as electrocatalyst for ethanol (concentration 1M) oxidation in basic media (1M KOH). Considering that the introduced nanoparticles composed of non precious metals and the obtained electrochemical results are satisfactory, the introduced study might open new avenues to the cobalt-based nanostructures to be used as novel electrocatalysts in the fuel cells applications.

Keywords: Direct ethanol fuel cells; Non precious catalysts; Cadmium-doped cobalt; Sol–gel

Large-scale preparation and morphology-dependent photodegradation performances of monodispersed AgBr crystals by Qinghua Liang; Yao Shi; Wangjing Ma; Zhi Li; Xinmin Yang (pp. 199-205).

Display Omitted► Monodispersed spherical, cubic and octahedral AgBr crystals were synthesized. ► Photodegradation performances were evaluated by decomposing Rhodamine B and methyl orange. ► AgBr octahedrons enclosed with {111} facets possessed the highest activities.The physicochemical properties of semiconductor catalysts depend intensively on their morphologies. Herein, three typical AgBr catalysts with well-defined spherical, cubic and octahedral shape were synthesized in a large scale through a facile ion exchange procedure controlled by a computerized double-jet apparatus. The as-synthesized monodispersed AgBr crystals were systematically characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), powder X-ray diffraction (XRD), and UV–vis diffuse reflection spectra (DRS). To clarify the relationship between photodegradation activities and structures, photodegradation performances of the AgBr crystals were evaluated by the degradation of Rhodamine B (RhB) and methyl orange (MO) aqueous solution under visible-light irradiation. The results demonstrated that the octahedral AgBr crystals exposed with {111} facets exhibited the highest photodegradation efficiency. Consequently, the present work is going to be instructive to develop the high efficient AgBr and other semiconductor photocatalysts for practical applications in the future.

Keywords: Photodegradation; Photoactivity; AgBr crystal; Morphology-dependent

Novel acidic ionic liquid polymer for biodiesel synthesis from waste oils by Xuezheng Liang (pp. 206-210).

Display Omitted► Solid acidic ionic liquid polymer with hydrophobic surface was synthesized. ► One-pot synthesis of biodiesel from waste oils was developed. ► Both the esterification and transesterification were efficiently catalyzed.The novel solid acidic ionic liquid polymer (PIL) has been synthesized through the copolymerization of acidic ionic liquid oligomers and divinylbenzene (DVB). Its catalytic activities were investigated through the biodiesel synthesis from waste oils. The results showed that the PIL was very efficient for both the transesterification of triglycerides and esterification of free fatty acids with the total yield over 99.0%. The catalytic activities were quite high with just one-step to complete the reactions simultaneously under very mild conditions. The PIL owned the advantages of high activities, high hydrophobic surface, high acidity and high stability.

Keywords: Solid acidic ionic liquid polymer; Hydrophobic; Biodiesel synthesis

Synthesis and characterization of Cu/N-doped mesoporous TiO₂ visible light photocatalysts by Chan-Soo Kim; Jung-Woo Shin; Young-Hyuck Cho; Hee-Dong Jang; Hong-Sik Byun; Tae-Oh Kim (pp. 211-218).

Display Omitted► Visible-light responsive Cu/N-doped mesoporous TiO₂ photocatalysts were synthesized. ► Cu/N-doped TiO₂ photocatalysts had a mesoporous structure and large specific area. ► Cu/N-doped mesoporous TiO₂ photocatalysts were responsive to visible light. ► Photocatalytic activity of Cu/N-doped mesoporous TiO₂ was greater than P25.Visible-light-responsive Cu/N-doped mesoporous TiO₂ photocatalysts were synthesized by a template-free homogenous coprecipitation method that was followed by an impregnation method. The photocatalysts were characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), the Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods, and ultraviolet–visible spectrophotometry. The Cu/N-doped TiO₂ photocatalysts had a well-defined mesoporous structure and large specific area and were responsive to visible light. On increasing the amount of Cu loaded, absorption in the visible-light range increased significantly, while the specific surface area and pore volume decreased. The photocatalytic activities were evaluated via the photodegradation of gaseous xylene under UV- and visible-light irradiation. The photocatalytic activity of Cu/N-doped mesoporous TiO₂ was considerably greater than that of both the sample undoped with Cu as well as that of commercially available TiO₂ (Degussa P25), which has low Cu content. Doping with nitrogen and Cu resulted in highly effective mesoporous TiO₂ photocatalysts that were responsive to visible light.

Keywords: Cu/N-doped mesoporous TiO; ₂; Visible-light response; Surface area

Kinetic study for the direct synthesis of dimethyl carbonate from methanol and CO₂ over CeO₂ at high pressure conditions by B.A.V. Santos; C.S.M. Pereira; V.M.T.M. Silva; J.M. Loureiro; A.E. Rodrigues (pp. 219-226).

Display Omitted► The kinetics for direct synthesis of DMC over CeO₂ at high pressure is studied. ► Model based on Langmuir–Hinshelwood mechanism fits our data. ► Δ_r H° and Δ_r G° were estimated to be −20.10 and 31.50kJmol⁻¹. ► The activation energy was estimated to be 106kJmol⁻¹. ► An activation volume was estimated to be −0.209cm³mol⁻¹.The kinetics for the direct synthesis of dimethyl carbonate was studied over CeO₂ at high pressure conditions in a batch reactor. Langmuir–Hinshelwood and Eley–Rideal mechanisms were proposed and compared by the performance of the respective reaction rate expression in fitting to the experimental kinetic data. The reactions were held at different temperatures (378–408K), CO₂/methanol molar ratios (1.1–4.0) and pressures (15–20MPa) in order to adjust the kinetic parameters. An activation energy of 106kJmol⁻¹, as well as the standard enthalpy and Gibbs energy of reaction (−20.10 and 31.50kJmol⁻¹) were calculated from experiments. Furthermore, the changes in pressure revealed an effect on the kinetic constant, with an activation volume equal to −0.208cm³mol⁻¹.

Keywords: Abbreviations; DMC; dimethyl carbonate; MeOH; methanol; mHV2; modified Huron–Vidal second order mixing rule; MC; methyl carbonate; NC; number of compounds; NP; number of points; SEM; scanning electron microscope; SRK; Soave–Redlich–Kwong equation of stateDimethyl carbonate; High pressure reaction; CeO; ₂

Adsorption and photocatalytic degradation of 2,4-dichlorophenol in TiO₂ suspensions. Effect of hydrogen peroxide, sodium peroxodisulphate and ozone by E. Pulido Melián; O. González Díaz; J.M. Doña Rodríguez; J. Araña; J. Pérez Peña (pp. 227-233).

Display Omitted► DCP degradation is fastest at pH 12 and mineralisation at pH 5. ► At pH 3, toxicity remains high and recalcitrant chlorinated intermediates are formed. ► The DCP adsorption isotherm fits the Freundlich model and the Langmuir model well. ► DCP interaction with the TiO₂ surface gives rise to the formation of a phenolate. ► H₂O₂ enhances the photocatalytic process while S₂O₈²⁻ has the opposite effect. 2,4-dichlorophenol (DCP) was decomposed in the presence of TiO₂ suspensions by illumination. The operating variables that were studied included initial DCP concentration, photocatalyst doses and initial pH. Mineralisation was slow at the optimum pH (12) for DCP degradation, with the optimum pH for both degradation and mineralisation being pH_o 5. The kinetic patterns were fitted to a first order kinetic. Adsorption and rate constants were obtained by using the Langmuir–Hinshelwood model. The adsorption isotherm was fitted to the Freundlich model and the Langmuir model with high coefficients of correlation. The adsorption constant in darkness was lower than that obtained with the kinetic model. According to the FTIR results, DCP–TiO₂ interaction occurs as a result of the formation of a phenolate. Of the three oxidants tested – hydrogen peroxide, ozone and sodium peroxodisulphate – only H₂O₂ resulted in enhancement of the photocatalytic process.

Keywords: Photocatalysis; TiO; ₂; ,; 2,4; -dichlorophenol; Hydrogen peroxide; Ozone; Peroxodisulphate

Vapor-phase methanol and ethanol coupling reactions on CuMgAl mixed metal oxides by Juan J. Bravo-Suárez; Bala Subramaniam; Raghunath V. Chaudhari (pp. 234-246).

Display Omitted► CuMgAlO_x mixed oxides were prepared from CuMgAl–CO₃ layered double hydroxides. ► CuMgAlO_x are the most active oxides for MeOH and EtOH coupling at moderate conditions. ► On CuMgAlO_x, CC coupling products are C₃₊ alcohols, C₃₊ aldehydes, and C₃₊ esters. ► Adsorbed alkoxides, carboxylates, and aldehyde oligomers were observed by in situ FTIR.The effects of catalyst composition on methanol and ethanol coupling reactions were studied on CuMgAlO_x mixed metal oxides (MMOs). CuMgAlO_x samples with Cu contents between 4 and 38at.% were prepared by thermal decomposition of layered double hydroxides. These MMOs contained highly dispersed CuO consisting of isolated and oligomeric CuO (number of CuO nearest neighbors between 2 and 4.5) species as determined by ultraviolet–visible spectroscopy and temperature programmed reduction techniques. The catalysts were tested at 448–523K, 0.1MPa, alcohols gas-hourly space velocities (GHSVs) of 1000–3000stdcm³g_cat⁻¹h⁻¹, and a feed MeOH/EtOH molar ratio of 4. Incorporation of Cu in MgAlO_x solid solutions drastically changed product selectivity, formation rates, and catalyst stability. The main products on CuMgAlO_x included CC coupling (e.g., C₃₊ alcohols, aldehydes, and esters), non-CC coupling (e.g., acetaldehyde, methyl formate, methyl acetate), and methanol decomposition (i.e., CO_x) products as a result of CC coupling reactions on MAl (M=Mg, Cu) and dehydrogenation, esterification, reverse methanol synthesis, and the water–gas shift reactions on Cu, respectively. The highest space-time yield of CC coupling products was 300gkg_cat⁻¹h⁻¹, obtained with CuMgAlO_x containing 21at.% Cu at 523K and an alcohols GHSV of 3000stdcm³g_cat⁻¹h⁻¹. In situ Fourier transform infrared spectroscopy during MeOH+EtOH, EtOH, and MeOH reactions on CuMgAlO_x and MgAlO_x suggested that surface carboxylates (formate and acetate) are spectator species whereas oligomeric forms of formaldehyde and acetaldehyde may be responsible for the deactivation of MgAlO_x.

Keywords: Alcohol coupling; Esterification; Layered double hydroxides; Mixed metal oxides; Infrared spectroscopy

Silica-supported PEI capped nanopalladium as potential catalyst in Suzuki, Heck and Sonogashira coupling reactions by Pitchaimani Veerakumar; Murugesan Velayudham; Kuang-Lieh Lu; Seenivasan Rajagopal (pp. 247-260).

Display Omitted► We have developed branched polymer PEI capped PdNPs for the coupling reactions. ► The Pd/SiO₂ gives high product yields and improved catalytic activity. ► Polyelectrolyte capped PdNPs is effective and stable catalytic system. ► It is a simple, convenient and novel method for the coupling reactions.We present the use of amine-functionalized silica (NH₂-SiO₂) as support for palladium nanoparticles (PdNPs) and the use of heterogeneous catalysts (Pd/NH₂-SiO₂) for the Suzuki, Heck and Sonogashira coupling reactions. The synthesized Pd catalyst is well characterized by XRD, HRTEM, BET, SEM-EDX, FT-IR, and UV–vis spectral techniques. It exhibits efficient catalytic activity for these coupling reactions without the assistance of ligand and copper salts.

Keywords: Silica; Heterogeneous; Palladium; Polyethylenimine; Catalysis

Iron oxide functionalised MIL-101 materials in aqueous phase selective oxidations by Alina Mariana Balu; Carol Sze Ki Lin; Hongli Liu; Yingwei Li; Carolina Vargas; Rafael Luque (pp. 261-266).

Display Omitted► Fe/MIL-101 was synthesized by a microwave methodology. ► Lewis acidity in materials was remarkably enhanced upon Fe incorporation. ► Fe/MIL-101 exhibited excelling activities in oxidations using hydrogen peroxide.A highly active Fe containing MIL-101 material has been prepared by using a simple microwave-assisted deposition methodology. The material, characterized by several techniques including N₂ physisorption, XPS and TEM, was found to have a significantly enhanced acidity due to the incorporation of ca. 2wt.% Fe in the form of hematite Fe₂O₃ phase. Fe/MIL-101 exhibited excelling activities in aqueous phase oxidations of alcohols and alkenes using hydrogen peroxide as green oxidant.

Keywords: Heterogeneous catalysis; Metal-organic frameworks; Microwave chemistry; Nanoparticles; Oxidation

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Applied Catalysis A, General (v.455, #)