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Chinese Journal of Catalysis
2016, Vol. 37, No. 4
Online: 30 March 2016


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Leng and coworkers in their Article on pages 468–475 synthesized several covalent organic frameworks with nitrogen ligands of tunable type and content. Both bipyridine and imine groups could coordinate with palladium acetate and the obtained heterogeneous catalyst could be utilized to catalyze the Heck reaction.

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Table of Contents for VOL.37 No.4 2016, 37 (4):  0-0.  Abstract ( 170 )   PDF (3763KB) ( 767 )

Review

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Nanosized and hierarchical zeolites: A short review Esmat Koohsaryan, Mansoor Anbia 2016, 37 (4):  447-467.  DOI: 10.1016/S1872-2067(15)61038-5 Abstract ( 1001 )   [Full Text(HTML)] () PDF (6540KB) ( 2230 )   Zeolites are crystalline aluminosilicates with three-dimensional microporous structures. They have been used as ion-exchangers, catalysts, and adsorbents in various fields such as oil refining, petrochemistry, agriculture, and water and wastewater treatment. Their wide use is because of their many beneficial properties, such as framework and compositional flexibilities, physical and hydrothermal stabilities, non-toxicity, high surface areas, exchangeable cations, and good cost-benefit ratios. Although many zeolite applications depend on their microporous structures, this can cause diffusional constraints for bulky reactant and product molecules. There have been many efforts to overcome the intrinsic limitations of conventional zeolites by preparing nanosized and hierarchically structured zeolites. As a result of these efforts, several strategies have been established and the use of new zeolitic materials in various catalytic and adsorptive reactions has been investigated. Longer lifetimes, high catalytic performances, and postponed coking and catalyst deactivation can be achieved using hierarchical and nanosized zeolites. The aim of this review is to provide an overview of the enhanced properties of hierarchical and nanosized zeolites, and recent development methods for their synthesis. The advantages and disadvantages of each route are discussed, and the catalytic applications of nanozeolites and zeolites with secondary porosity, and a comparison with conventional zeolites, are briefly presented.

Articles

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Nitrogen ligands in two-dimensional covalent organic frameworks for metal catalysis Jianqiang Zhang, Yongsheng Peng, Wenguang Leng, Yanan Gao, Feifei Xu, Jinling Chai 2016, 37 (4):  468-475.  DOI: 10.1016/S1872-2067(15)61050-6 Abstract ( 588 )   [Full Text(HTML)] () PDF (769KB) ( 1344 )   We introduced bipyridine ligands into a series of two-dimensional (2D) covalent organic frameworks (COFs) using 2,2'-bipyridine-5,5'-dicarbaldehyde (2,2'-BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2'-BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyridine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be varied, with one ligand favoring binding in the space between adjacent COFs' layers and the other ligand favoring binding within the pores of the COFs. The Pd(II)-loaded COFs exhibited good catalytic activity for the Heck reaction.

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Catalytic nucleophilic addition of terminal alkynes to α,β-unsaturated-γ-lactams Maorong Wang, Bao Gao, Hanmin Huang 2016, 37 (4):  476-483.  DOI: 10.1016/S1872-2067(15)61057-9 Abstract ( 511 )   [Full Text(HTML)] () PDF (638KB) ( 826 )   A novel catalytic reaction has been developed for the nucleophilic addition of terminal alkynes to α,β-unsaturated-γ-lactams via a cyclic N-acyliminium ion intermediate. This simple reaction proceeds rapidly under mild conditions, and provided a practical approach for the synthesis of a wide range of 5-alkynyl-2-pyrrolidinones in moderate to good yields (45%-76%).

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Highly active Cu/SiO2 catalysts for hydrogenation of diethyl malonate to 1,3-propanediol Tongmei Ding, Hengshui Tian, Jichang Liu, Wenbin Wu, Jintao Yu 2016, 37 (4):  484-493.  DOI: 10.1016/S1872-2067(15)61053-1 Abstract ( 352 )   [Full Text(HTML)] () PDF (1485KB) ( 1075 )   Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3-propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO2 catalysts, which were systematically characterized by N2 adsorption-desorption, inductively coupled plasma-atomic emission spectroscopy, N2O chemisorption, X-ray diffraction, Fourier transform infrared spectroscopy, H2 temperature-programmed reduction, transmission electron microscopy, and X-ray photoelectron spectroscopy. When the Cu/SiO2 catalyst was calcined at 723 K, 90.7% conversion of diethyl malonate and 32.3% selectivity of 1,3-propanediol were achieved. Compared with Cu/SiO2 catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO2 catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu+/Cu0. The synergetic effect of Cu0 and Cu+ is suggested to be responsible for the optimum activity.

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Application of sodium titanate nanotubes doped with vanadium (VNaTNT) as a heterogeneous catalyst for oxidation of sulfides at room temperature Mohammad Ali Dadvar, Razieh Fazaeli 2016, 37 (4):  494-501.  DOI: 10.1016/S1872-2067(15)61056-7 Abstract ( 318 )   [Full Text(HTML)] () PDF (1332KB) ( 935 )   A heterogeneous titanate nanotube (TNT) catalyst containing TiO2, Na, and V has been synthesized and used in the chemoselective oxidation of sulfides to the corresponding sulfoxides in the presence of 30% H2O2 in water. Some of the advantages of our method include excellent yields, heterogeneous conditions, simplicity, compatibility with a variety of functionalities, and ease of isolation of the products. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption were used for structural and textural characterization of the catalyst (VNaTNT).

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Selective oxidation of glycerol to lactic acid over activated carbon supported Pt catalyst in alkaline solution Chen Zhang, Tao Wang, Xiao Liu, Yunjie Ding 2016, 37 (4):  502-509.  DOI: 10.1016/S1872-2067(15)61055-5 Abstract ( 335 )   [Full Text(HTML)] () PDF (786KB) ( 1086 )   Pt/activated carbon (Pt/AC) catalyst combined with base works efficiently for lactic acid production from glycerol under mild conditions. Base type (LiOH, NaOH, KOH, or Ba(OH)2) and base/glycerol molar ratio significantly affected the catalytic performance. The corresponding lactic acid selectivity was in the order of LiOH > NaOH > KOH > Ba(OH)2. An increase in LiOH/glycerol molar ratio elevated the glycerol conversion and lactic acid selectivity to some degree, but excess LiOH inhibited the transformation of glycerol to lactic acid. In the presence of Pt/AC catalyst, the maximum selectivity of lactic acid was 69.3% at a glycerol conversion of 100% after 6 h at 90 ℃, with a LiOH/glycerol molar ratio of 1.5. The Pt/AC catalyst was recycled five times and was found to exhibit slightly decreased glycerol conversion and stable lactic acid selectivity. In addition, the experimental results indicated that reaction intermediate dihydroxyacetone was more favorable as the starting reagent for lactic acid formation than glyceraldehyde. However, the Pt/AC catalyst had adverse effects on the intermediate transformation to lactic acid, because it favored the catalytic oxidation of them to glyceric acid.

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Effects of zinc on Fe-based catalysts during the synthesis of light olefins from the Fischer-Tropsch process Xinhua Gao, Jianli Zhang, Ning Chen, Qingxiang Ma, Subing Fan, Tiansheng Zhao, Noritatsu Tsubaki 2016, 37 (4):  510-516.  DOI: 10.1016/S1872-2067(15)61051-8 Abstract ( 458 )   [Full Text(HTML)] () PDF (822KB) ( 1254 )   Fe-based catalysts for the production of light olefins via the Fischer-Tropsch synthesis were modified by adding a Zn promoter using both microwave-hydrothermal and impregnation methods. The physicochemical properties of the resulting catalysts were determined by scanning electron microscopy, the Brunauer-Emmett-Teller method, X-ray diffraction, H2 temperature-programed reduction and X-ray photoelectron spectroscopy. The results demonstrate that the addition of a Zn promoter improves both the light olefin selectivity over the catalyst and the catalyst stability. The catalysts prepared via the impregnation method, which contain greater quantities of surface ZnO, exhibit severe carbon deposition following activity trials. In contrast, those materials synthesized using the microwave-hydrothermal approach show improved dispersion of Zn and Fe phases and decreased carbon deposition, and so exhibit better CO conversion and stability.

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An environmentally-friendly base organocatalyzed one-pot strategy for the regioselective synthesis of novel 3,6-diaryl-4-methylpyridazines Mehdi Rimaz, Farkhondeh Aali 2016, 37 (4):  517-525.  DOI: 10.1016/S1872-2067(15)61060-9 Abstract ( 295 )   [Full Text(HTML)] () PDF (904KB) ( 754 )   This report describes a new three-component strategy for the regioselective synthesis of a series of tri-substituted pyridazines via a 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalyzed condensation of propiophenones, arylglyoxalmonohydrates and hydrazine hydrate in water. This method provides a green and convenient one-pot route toward a diverse set of 3,6-diaryl-4-methylpyridazines bearing various aryl substituents. This procedure is highly regioselective, operationally simple, uses water as a safe, environmentally friendly solvent, and DABCO as a green base-organocatalyst, and affords good to excellent yields of products.

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Derived oil production by catalytic pyrolysis of scrap tires Wei Li, Chuanfeng Huang, Dapeng Li, Pengju Huo, Mingfeng Wang, Lei Han, Gang Chen, Huihui Li, Xiaohong Li, Yongjuan Wang, Mengyan Wang 2016, 37 (4):  526-532.  DOI: 10.1016/S1872-2067(15)60998-6 Abstract ( 391 )   [Full Text(HTML)] () PDF (1526KB) ( 1143 )   Scrap tires were pyrolyzed in a continuously stirred batch reactor in the presence and absence of catalysts. The maximum yield of derived oil was up to 55.65 wt% at the optimum temperature, 500 ℃. The catalytic pyrolysis was performed using 1.0 wt% (on a scrap tire weight basis) of catalysts based on ZSM-5, USY, β, SAPO-11, and ZSM-22. The oil products were characterized using simulation distillation, elemental analysis, and gas chromatography-mass spectrometry. The results show that using a catalyst can increase the conversion of scrap tires to gas and decrease char by-products; the yield of derived oil remains unchanged or a little lower. The oils derived from catalytic pyrolysis had H/C ratios of 1.55-1.65 and contained approximately 70-75 wt% light oil, 0.3-0.58 wt% S and 0.78-1.0 wt% N. Catalysts with high acid strengths and appropriate pore sizes, such as ZSM-5, USY, β, and SAPO-11, increased the amount of single-ring aromatics in the light-middle-fraction oil to 45 wt%. The derived oil can therefore be used as a petrochemical feedstock for producing high-value-added chemical products or fuel oil.

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Synthesis of nitrocarbazole compounds and their electrocatalytic oxidation of alcohol Yinghong Zhu, Jianqing Zhang, Ziying Chen, Anlun Zhang, Chunan Ma 2016, 37 (4):  533-538.  DOI: 10.1016/S1872-2067(15)61047-6 Abstract ( 659 )   [Full Text(HTML)] () PDF (607KB) ( 859 )   Three compounds with nitrocarbazole frameworks were synthesized and their electrochemical reversibility as organic electrocatalysts was studied by cyclic voltammetry. The electrochemical reversibility and oxidation-reduction potential of the compounds were greatly affected by their substituents. The oxidation-reduction potential of the compound with an electron-donating group was negative, while that of the compound with an electron-withdrawing group on the carbazole framework was positive. The electrocatalytic oxidation activities of the nitrocarbazole compounds were investigated through cyclic voltammetry and controlled potential electrolysis at room temperature. The electrocatalysts showed excellent selectivity for p-methoxybenzyl alcohol, converting it to the corresponding aldehyde through electro-oxidation with just 2.5 mol% of the electrocatalysts presented. The electrocatalysts maintained their excellent electroredox activity following recycling.

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A Fe-N-C catalyst with highly dispersed iron in carbon for oxygen reduction reaction and its application in direct methanol fuel cells Lingzheng Gu, Luhua Jiang, Xuning Li, Jutao Jin, Junhu Wang, Gongquan Sun 2016, 37 (4):  539-548.  DOI: 10.1016/S1872-2067(15)61049-X Abstract ( 485 )   [Full Text(HTML)] () PDF (1182KB) ( 1189 )   Exploring non-precious metal catalysts for the oxygen reduction reaction (ORR) is essential for fuel cells and metal-air batteries. Herein, we report a Fe-N-C catalyst possessing a high specific surface area (1501 m2/g) and uniformly dispersed iron within a carbon matrix prepared via a two-step pyrolysis process. The Fe-N-C catalyst exhibits excellent ORR activity in 0.1 mol/L NaOH electrolyte (onset potential, Eo = 1.08 V and half wave potential, E1/2 = 0.88 V vs. reversible hydrogen electrode) and 0.1 mol/L HClO4 electrolyte (Eo = 0.85 V and E1/2 = 0.75 V vs. reversible hydrogen electrode). The direct methanol fuel cells employing Fe-N-C as the cathodic catalyst displayed promising performance with a maximum power density of 33 mW/cm2 in alkaline media and 47 mW/cm2 in acidic media. The detailed investigation on the composition-structure- performance relationship by X-ray diffraction, X-ray photoelectron spectroscopy and Mössbauer spectroscopy suggests that Fe-N4, together with graphitic-N and pyridinic-N are the active ORR components. The promising direct methanol fuel cell performance displayed by the Fe-N-C catalyst is related to the intrinsic high catalytic activity, and critically for this application, to the high methanol tolerance.

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Electrocatalytic oxidation of hydrazine on magnetic bar carbon paste electrode modified with benzothiazole and iron oxide nanoparticles: Simultaneous determination of hydrazine and phenol Ali Benvidi, Shahriar Jahanbani, Bibi-Fatemeh Mirjalili, Reza Zare 2016, 37 (4):  549-560.  DOI: 10.1016/S1872-2067(15)61046-4 Abstract ( 316 )   [Full Text(HTML)] () PDF (897KB) ( 830 )   A magnetic bar carbon paste electrode (MBCPE) modified with Fe3O4 magnetic nanoparticles (Fe3O4NPs) and 2-(3,4-dihydroxyphenyl) benzothiazole (DPB) for the electrochemical determination of hydrazine was developed. The DPB was firstly self-assembled on the Fe3O4NPs, and the resulting Fe3O4NPs/DPB composite was then absorbed on the designed MBCPE. The MBCPE was used to attract the magnetic nanoparticles to the electrode surface. Owing to its high conductivity and large effective surface area, the novel electrode had a very large current response for the electrocatalytic oxidation of hydrazine. The modified electrode was characterized by voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, infrared spectroscopy, and UV-visible spectroscopy. Voltammetric methods were used to study the electrochemical behaviour of hydrazine on MBCPE/Fe3O4NPs/DPB in phosphate buffer solution (pH = 7.0). The MBCPE/ Fe3O4NPs/DPB, acting as an electrochemical sensor, exhibited very high electrocatalytic activity for the oxidation of hydrazine. The presence of DPB was found to reduce the oxidation potential of hydrazine and increase the catalytic current. The dependence of the electrocatalytic current on the hydrazine concentration exhibited two linear ranges, 0.1-0.4 μmol/L and 0.7-12.0 μmol/L, with a detection limit of 18.0 nmol/L. Additionally, the simultaneous determination of hydrazine and phenol was investigated using the MBCPE/Fe3O4NPs/DPB electrode. Voltammetric experiments showed a linear range of 100-470 μmol/L and a detection limit of 24.3 μmol/L for phenol, and the proposed electrode was applied to the determination of hydrazine and phenol in water samples.

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Purification and characterization of manganese peroxidases from native and mutant Trametes versicolor IBL-04 Muhammad Asgher, Muhammad Ramzan, Muhammad Bilal 2016, 37 (4):  561-570.  DOI: 10.1016/S1872-2067(15)61044-0 Abstract ( 389 )   [Full Text(HTML)] () PDF (488KB) ( 1223 )   Extracellular manganese peroxidases (MnPs) produced by native and mutant strains of Trametes versicolor IBL-04 (EB-60, EMS-90) were purified by ammonium sulphate precipitation and dialysis, followed by ion-exchange and gel-permeation chromatography. The purified enzymes elucidated a single band in the 43-kDa region on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The optimum pH and temperature of the purified enzymes were found to be 5.0 and 40 ℃, respectively. Mutant strain MnPs exhibited a broader active pH range and higher thermal stability than native MnP. Purified MnPs from selected mutants showed almost identical properties to native MnP in electrophoresis, steady-state kinetics, and metal ion and endocrine-disrupting compound (EDC) degradation efficiency. Although the fastest reaction rates occurred with Mn2+, MnPs displayed the highest affinity for ABTS, methoxyhydroquinone, 4-aminophenol and reactive dyes. MnP activity was significantly enhanced by Mn2+ and Cu2+, and inhibited in the presence of Zn2+, Fe2+, ethylenediaminetetraacetic acid and cysteine to various extents, with Hg2+ as the most potent inhibitory agent. MnPs from all sources efficiently catalyzed the degradation of the EDCs, nonylphenol and triclosan, removing over 80% after 3 h of treatment, which was further increased up to 90% in the presence of MnP-mediator system. The properties of T. versicolor MnPs, such as high pH and thermal stability, as well as unique Michaelis-Menten kinetic parameters and high EDC elimination efficiency, render them promising candidates for industrial exploitation.

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Iron(III) phthalocyanine chloride-catalyzed oxidation-aromatization of α,β-unsaturated ketones with hydrazine hydrate: Synthesis of 3,5-disubstituted 1H-pyrazoles Junlong Zhao, Jun Qiu, Xiaofeng Gou, Chengwen Hua, Bang Chen 2016, 37 (4):  571-578.  DOI: 10.1016/S1872-2067(15)61043-9 Abstract ( 572 )   [Full Text(HTML)] () PDF (810KB) ( 1022 )   We have developed an iron(III) phthalocyanine chloride-catalyzed oxidation-aromatization of α,β-unsaturated ketones with hydrazine hydrate. Various 3,5-disubstituted 1H-pyrazoles were obtained in good to excellent yields. This method offers several advantages, including room- temperature conditions, short reaction time, high yields, simple work-up procedure, and use of air as an oxidant. The catalyst can be recovered and reused five times without loss of activity.

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Determination of isoproterenol in pharmaceutical and biological samples using a pyrogallol red multiwalled carbon nanotube paste electrode as a sensor Mohsen Keyvanfard, Khadijeh Alizad 2016, 37 (4):  579-583.  DOI: 10.1016/S1872-2067(15)61036-1 Abstract ( 305 )   [Full Text(HTML)] () PDF (560KB) ( 818 )   Isoproterenol (ISPR) is an important catecholamine-based drug that is widely used in the treatment of heart disease. However, overdose of this drug is very dangerous to the human body. In this study, a new sensor based on a pyrogallol red modified-multiwalled carbon nanotube paste electrode (PGRMMWCNTPE) was prepared and used for high sensitivity determination of ISPR in aqueous solution. Electrocatalytic oxidation of ISPR at the PGRMMWCNTPE was investigated by chronoamperometry, cyclic voltammetry, and square-wave voltammetry. The values of the catalytic rate constant, electron transfer coefficient, and diffusion coefficient for ISPR oxidation were then calculated using voltammetric data. A linear calibration curve was constructed for ISPR concentration in the range 0.8-570 μmol/L with a detection limit of 0.47 μmol/L ISPR. The sensor was then applied to the determination of ISPR in urine and drug samples with satisfactory results.

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A magnetic biocatalyst based on mussel-inspired polydopamine and its acylation of dihydromyricetin Xiao Deng, Shilin Cao, Ning Li, Hong Wu, Thomas J. Smith, Minhua Zong, Wenyong Lou 2016, 37 (4):  584-595.  DOI: 10.1016/S1872-2067(15)61045-2 Abstract ( 562 )   [Full Text(HTML)] () PDF (965KB) ( 1134 )   A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles (PD-MNPs) was prepared and characterized. The widely used Aspergillus niger lipase (ANL) was immobilized on the PD-MNPs (ANL@PD-MNPs) with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significantly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy. A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin (DMY) in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.

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Kinetic study and kinetic parameters of lipase-catalyzed glycerolysis of sardine oil in a homogeneous medium Ángela García Solaesa, María Teresa Sanz, Sagrario Beltrán, Rodrigo Melgosa 2016, 37 (4):  596-606.  DOI: 10.1016/S1872-2067(15)61040-3 Abstract ( 416 )   [Full Text(HTML)] () PDF (600KB) ( 1059 )   The production of polyunsaturated fatty acids (PUFAs) concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic catalysts. The enzymatic glycerolysis of sardine oil by Lipozyme® 435 to get PUFA concentrates in the forms of di- and monoacylglycerols (DAGs, MAGs) in an optimized amount of tert-butanol as the organic solvent was studied. First, mass transfer limitation of the reaction system was analyzed. The effects of different operating variables such as lipase loading, temperature and feed composition were investigated. A semi-empirical kinetic model based on the reversible elementary reactions of glycerolysis and hydrolysis of the glycerides was employed to correlate the experimental kinetic data. A molar ratio glycerol:oil of 3:1 was the optimum, which produced more than 84 wt% of MAG at 323 K. A comparison with other glycerolysis systems was performed using MAG yield, reaction rate and significance of kinetic parameters.

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Photocatalytic degradation of 2,4-dichlorophenol with V2O5-TiO2 catalysts: Effect of catalyst support and surfactant additives Eda Sinirtas, Meltem Isleyen, Gulin Selda Pozan Soylu 2016, 37 (4):  607-615.  DOI: 10.1016/S1872-2067(15)61035-X Abstract ( 261 )   [Full Text(HTML)] () PDF (845KB) ( 1026 )   Binary oxide catalysts with various weight percentage V2O5 loadings were prepared by solid-state dispersion and the nanocomposites were modified with surfactants. The catalysts were analyzed using X-ray diffraction, diffuse-reflectance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption-desorption. The photocatalytic activities of the catalysts were evaluated in the degradation of 2,4-dichlorophenol under ultraviolet irradiation. The photocatalytic activity of 50 wt% V2O5-TiO2 (50V2O5-TiO2) was higher than those of pure V2O5, TiO2, and P25. Interactions between V2O5 and TiO2 affected the photocatalytic efficiencies of the binary oxide catalysts. Cetyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium bromide (HTAB) significantly enhanced the efficiency of the 50V2O5-TiO2 catalyst. The highest percentage of 2,4-dichlorophenol degradation (100%) and highest reaction rate (2.22 mg/(L·min)) were obtained in 30 min with the (50V2O5-TiO2)-CTAB catalyst. It is concluded that the addition of a surfactant to the binary oxide significantly enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.

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Electrooxidation of methanol and ethanol on carbon electrodeposited Ni-MgO nanocomposite H. B. Hassan, Z. Abdel Hamid, Rabab M. El-Sherif 2016, 37 (4):  616-627.  DOI: 10.1016/S1872-2067(15)61034-8 Abstract ( 442 )   [Full Text(HTML)] () PDF (870KB) ( 917 )   Ni-MgO nano-composites were prepared on carbon anodes by electrodeposition from a nickel Watts bath in the presence of fine MgO reinforcement particles. Their performance as electrocatalysts for the oxidation of methanol and ethanol in alkaline medium was investigated and compared with that of carbon coated pure Ni (Ni/C). The chemical composition, phase structure, and surface morphology of the deposited nano-composites were studied by energy dispersive X-ray spectroscopy, X-ray diffractometry, and scanning electron microscopy, respectively. Different electrochemical techniques were used to estimate the catalytic activity of the prepared electrocatalyst anodes, including cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The Ni/C electrocatalyst alone exhibited remarkably low catalytic activity and poor stability toward the electrooxidation process. The inclusion of MgO significantly promoted the catalytic activity of the Ni catalyst for the alcohol electrooxidation and enhanced its poisoning resistance. The EIS results confirmed those of CV and revealed a lower charge transfer resistance and enhanced roughness for the Ni-MgO/C nano-composite electrodes compared with those of Ni/C.

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A novel method for enhancing the stability of ZSM-5 zeolites used for catalytic cracking of LPG: Catalyst modification by dealumination and subsequent silicon loading Leyla Vafi, Ramin Karimzadeh 2016, 37 (4):  628-635.  DOI: 10.1016/S1872-2067(15)61062-2 Abstract ( 371 )   [Full Text(HTML)] () PDF (685KB) ( 1152 )   Composite structures of ZSM-5 zeolites were prepared by the synthesis of mesopores and micropores using carbon nanotubes as a template. Dealumination of mesopores was performed selectively using trichloroacetic acid, which could only diffuse into the mesopores and not the micropores owing to the size of the trichloroacetic acid molecules. Empty spaces are created in the catalyst as a result of removal of the Al atoms from the zeolite structure. If Si atoms fill the empty space, then the structure of the mesopores becomes similar to silicates, which do not have any catalytic properties. Silicon containing solution was used to fill the empty spaces, and in doing so, a unique method was developed, by which silicon atoms can directly replace the extracted Al atoms from the mesopore structure. Therefore, by changing the geometry and properties of the mesopores and micropores, the amount of coke reduced from 14% for HZSM-5 to 3% for the modified zeolite.