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Chinese Journal of Catalysis
2014, Vol. 35, No. 3
Online: 26 February 2014


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Fan et al. in their Article on pages 286–293 show that the physico- chemical properties and catalytic performance of propane ammoxidation over Ni-Mo nitride catalysts are strongly dependent on the preparation methods of the oxide precursors. The nitrogen species in Ni-Mo nitride play an important role in the selectivity of acrylonitrile for propane ammoxidation.

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Table of Contents for VOL.35 No.3 2014, 35 (3):  0-0.  Abstract ( 190 )   PDF (2617KB) ( 436 )

Communications

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Cyclohexane oxidation：Small organic molecules as catalysts Yicheng Zhang, Weili Dai, Guangjun Wu, Naijia Guan, Landong Li 2014, 35 (3):  279-285.  DOI: 10.1016/S1872-2067(14)60024-3 Abstract ( 321 )   [Full Text(HTML)] () PDF (427KB) ( 942 )   The catalytic activity of several small organic molecules including ketones, aldehydes, esters, alcohols and amines toward cyclohexane oxidation was investigated. The catalytic activity was found to be closely related to polarity, α-H activity, the strength of hydrogen bond formed with cyclohexane and the radical scavenging capability of these molecules. Based on the obtained results, the catalytic role of the organic solvent must be considered for cyclohexane oxidation. Tripropylamine has very high activity in cyclohexane oxidation and it might be further developed as a promising small-molecule organocatalyst for future application.

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Ni-Mo nitride catalysts：Synthesis and application in the ammoxidation of propane Xiaoqiang Fan, Huimin Zhang, Jianmei Li, Zhen Zhao, Chunming Xu, Jian Liu, Aijun Duan, Guiyuan Jiang, Yuechang Wei 2014, 35 (3):  286-293.  DOI: 10.1016/S1872-2067(14)60015-2 Abstract ( 295 )   [Full Text(HTML)] () PDF (610KB) ( 834 )   Five different methods were used to prepare the Ni-Mo oxide precursors including sol-gel, rotary evaporation-microwave drying, co-precipitation, impregnation, and mechanical mixing. Ni-Mo nitride catalysts have been synthesized by temperature-programmed nitration of the oxide precursors in a flow of H2 and N2. The structure and physico-chemical properties of the Ni-Mo oxide precursors and their corresponding nitride catalysts were determined by X-ray diffraction, total nitrogen content analysis, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction, and their catalytic performance for propane ammoxidation was also tested. The catalytic activity and selectivity towards the formation of acrylonitrile over the Ni-Mo nitride catalysts are strongly dependent on the preparation methods for the oxide precursors. The N species in the Ni-Mo nitrides and their mobility and reactivity affect the selectivity for acrylonitrile. The Ni-Mo nitride prepared by co-precipitation, with the largest amount and more reactive N species, exhibited the highest catalytic activity and selectivity for acrylonitrile.

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In situ DRIFTS study of the mechanism of low temperature selective catalytic reduction over manganese-iron oxides Ting Chen, Bin Guan, He Lin, Lin Zhu 2014, 35 (3):  294-301.  DOI: 10.1016/S1872-2067(12)60730-X Abstract ( 428 )   [Full Text(HTML)] () PDF (692KB) ( 664 )   To investigate the mechanism of selective catalytic reduction (SCR) of NOx with NH3, Ti0.9Mn0.05Fe0.05O2-δ catalyst was prepared by self-propagating high-temperature synthesis (SHS) method and evaluated at 25-450℃. The catalyst was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The possible SCR mechanism over Ti0.9Mn0.05Fe0.05O2-δ was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Ti0.9Mn0.05Fe0.05O2-δ showed both high SCR activity and N2 selectivity over a broad temperature window of 100-350℃. The XRD and TEM results indicated that the active components of Mn and Fe were in a highly dispersed state and in an amorphous form on TiO2. The DRIFTS results revealed that Brönsted acid sites were the active centers for NO removal and monodentate nitrates were the key intermediate in the SCR reaction. At 150℃, both Langmuir-Hinshelwood and Eley-Rideal mechanisms are involved in the SCR reaction, while the former one mechanism dominates the catalytic activity of Ti0.9Mn0.05Fe0.05O2-δ. Additionally, the presence of O2 significantly affects NO oxidation and coordinated NH3 activation.

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Effect of calcination temperature of Ni/SiO2-ZrO2 catalyst on its hydrodeoxygenation of guaiacol Xinghua Zhang, Qi Zhang, Lungang Chen, Ying Xu, Tiejun Wang, Longlong Ma 2014, 35 (3):  302-309.  DOI: 10.1016/S1872-2067(12)60733-5 Abstract ( 404 )   [Full Text(HTML)] () PDF (857KB) ( 819 )   SiO2-ZrO2 composites were synthesized by chemical precipitation and used to prepare a series of bifunctional Ni/SiO2-ZrO2 catalysts by impregnation. The effect of calcination temperature on the catalyst structure and its catalysis of the hydrodeoxygenation of guaiacol was investigated. Guaiacol was converted to cyclohexane by a synergism between the metal center and solid acid support. The catalyst calcined at 500℃ gave a maximum 100% guaiacol conversion and 96.8% selectivity for cyclohexane. The catalyst samples were characterized by N2 adsorption, H2 chemisorption, X-ray diffraction, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, and Raman spectroscopy. The synthesized SiO2-ZrO2 was an amorphous oxide. The Ni/SiO2-ZrO2 catalyst calcined at 500℃ has more acidity, smaller NiO particles, and larger BET surface area and pore volume, which gave it the best catalytic performance.

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Transesterification of glycerol with dimethyl carbonate over Mg-Al hydrotalcites Liping Zheng, Shuixin Xia, Zhaotong Hou, Mengyuan Zhang, Zhaoyin Hou 2014, 35 (3):  310-318.  DOI: 10.1016/S1872-2067(12)60738-4 Abstract ( 255 )   [Full Text(HTML)] () PDF (1310KB) ( 850 )   Glycerol carbonate (GC) was synthesized via the catalytic transesterification of glycerol with dimethyl carbonate over a series of Mg-Al hydrotalcites with different Mg/Al ratios (0.5-6) under mild conditions. All catalysts exhibited a high selectivity toward GC. The sample with Mg/Al=2 exhibited 97.1% of selectivity toward GC and 66.9% of glycerol conversion at 70℃ for 3 h. Characterization results indicated that the activity of calcined Mg-Al hydrotalcites depended mainly on the surface area, pore diameter, and crystallinity.

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Highly efficient and clean synthesis of 1-amino-2-acetylanthraquinone by copper-catalyzed reductive cleavage of isoxazole motif Zhongkui Zhao, Renzhi Li, Yu Li 2014, 35 (3):  319-323.  DOI: 10.1016/S1872-2067(12)60743-8 Abstract ( 394 )   [Full Text(HTML)] () PDF (558KB) ( 691 )   A clean and highly efficient synthesis of 1-amino-2-acetylanthraquinone via reductive isoxazole ring cleavage of 3-methylanthra[1,2-c]isoxazole-6,11-dione catalyzed by trace copper using hydrazine hydrate as a clean reducing agent and water as a green reaction medium under mild reaction conditions was investigated. Various transition-metal catalysts were screened for the reductive ring-opening reaction, and Cu(NO3)2 was shown to be an excellent catalyst. A conversion of 97.2% and 1-amino-2-acetylanthraquinone selectivity greater than 95% were obtained in the presence of 2.6 mol% Cu(NO3)2 (turnover number 38) with 1.3 equiv. of hydrazine hydrate for 2 h in water. The structure of the product was confirmed by 1H nuclear magnetic resonance spectroscopy and mass spectrometry; the main byproduct was hydroxyl-substituted 1-amino-2-acetylanthraquinone. A possible reaction mechanism for the copper-catalyzed ring cleavage of 3-methylanthra[1,2-c]isoxazole-6,11-dione with hydrazine hydrate was proposed.

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Poly(vinyl chloride)-supported Pd(Ⅱ) complex as an efficient catalyst for Heck and Cu-free Sonogashira reactions under aerobic conditions Mohammad Bakherad, Ali Keivanloo, Shahrzad Samangooei 2014, 35 (3):  324-328.  DOI: 10.1016/S1872-2067(12)60746-3 Abstract ( 283 )   [Full Text(HTML)] () PDF (591KB) ( 705 )   A novel poly(vinyl chloride)-supported Pd complex was found to be a highly active catalyst for the Heck and Sonogashira reactions of aryl halides under aerobic conditions. The complex is thermally stable, and can be easily recovered and reused. The catalyst was recycled for the Heck and Sonogashira reactions for five runs without appreciable loss of its catalytic activity, and with negligible metal leaching.

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Poly(4-vinylpyridinium) perchlorate as an efficient solid acid catalyst for the chemoselective preparation of 1,1-diacetates from aldehydes under solvent-free conditions Nader Ghaffari Khaligh 2014, 35 (3):  329-334.  DOI: 10.1016/S1872-2067(12)60750-5 Abstract ( 277 )   [Full Text(HTML)] () PDF (441KB) ( 462 )   Poly(4-vinylpyridinium) perchlorate has been used as a supported, recyclable, environmentally-benign catalyst for the formation of acylals from aliphatic and aromatic aldehydes in good to excellent yields under solvent-free conditions. Notably, the reaction conditions were tolerant of ketones. This methodology offers several distinct advantages, including its operational simplicity and high product yield, as well as being green in terms of avoiding the use of toxic catalysts and solvents. Furthermore, the catalyst can be recovered and reused several times without any loss in its activity.

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The effects of Mn loading on the structure and ozone decomposition activity of MnOx supported on activated carbon Mingxiao Wang, Pengyi Zhang, Jinge Li, Chuanjia Jiang 2014, 35 (3):  335-341.  DOI: 10.1016/S1872-2067(12)60756-6 Abstract ( 399 )   [Full Text(HTML)] () PDF (942KB) ( 1118 )   Manganese oxide catalysts supported on activated carbon (AC, MnOx/AC) for ozone decomposition were prepared by in situ reduction of the permanganate. The morphology, oxidation state, and crystal phase of the supported manganese oxide were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electron spin resonance, Raman spectroscopy, and temperature-programmed reduction. The supported MnOx layer was distributed on the surface of AC with a morphology that changed from a porous lichen-like structure to stacked nanospheres, and the thickness of the MnOx layer increased from 180 nm to 710 nm when the Mn loading was increased from 0.44% to 11%. The crystal phase changed from poorly crystalline β-MnOOH to δ-MnO2 with the oxidation state of Mn increasing from +2.9-+3.1 to +3.7-+3.8. The activity for the decomposition of low concentration ozone at room temperature was related to the morphology and loading of the supported MnOx. The 1.1% MnOx/AC showed the best performance, which was due to its porous lichen-like structure and relatively high Mn loading, while 11% MnOx/AC with the thickest MnOx layer had the lowest activity owning to its compact morphology.

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Cobalt-based catalysts derived from cobalt carbonyl clusters for Fischer-Tropsch synthesis Xuefen Li, Fenghua Bai, Haiquan Su 2014, 35 (3):  342-350.  DOI: 10.1016/S1872-2067(12)60757-8 Abstract ( 202 )   [Full Text(HTML)] () PDF (1069KB) ( 701 )   Co catalysts supported on γ-Al2O3 were prepared using Co2(CO)6HCCCOOH, Co3(CO)9CCH2COOH, and Co4(CO)10HCCCOOH as precursors. Co(NO3)2 was used as the precursor for preparing the reference catalyst. The results of Fischer-Tropsch synthesis tests and characterization by transmission electron microscopy, NH3 temperature-programmed desorption, and infrared showed that the different precursors have significant effects on the dispersion of the Co, which affect their catalytic behavior. CO conversion and C5+ selectivity over these catalysts prepared from different precursors decreased in the order Co3(CO)9CCH2COOH > Co2(CO)6HCCCOOH > Co4(CO)10HCCCOOH > Co(NO3)2.

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Preparation and characterization of nano-CaO based on eggshell waste：Novel and green catalytic approach to highly efficient synthesis of pyrano[4,3-b]pyrans Elaheh Mosaddegh, Asadollah Hassankhani 2014, 35 (3):  351-356.  DOI: 10.1016/S1872-2067(12)60755-4 Abstract ( 315 )   [Full Text(HTML)] () PDF (880KB) ( 2781 )   Nano-CaO was prepared by calcination of ball-milled chicken eggshell waste. This novel, bioactive, heterogeneous catalyst, which had high catalytic activity and reusability, was used in the green synthesis of pyrano[4,3-b]pyrans via condensation of various aromatic aldehydes, malononitrile, and 4-hydroxy-6-methyl-2H-pyran-2-one at 120℃ under solvent-free conditions. The reaction proceeded to completion within 5-45 min in 93%-98% yield. The nano-CaO was fully characterized by scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, X-ray fluorescence spectroscopy, and thermal gravimetric, surface area, and elemental analyses.

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Pd/C-catalyzed ligand-free and aerobic Suzuki reaction in water Xiaofeng Rao, Chun Liu, Yixia Zhang, Zhanming Gao, Zilin Jin 2014, 35 (3):  357-361.  DOI: 10.1016/S1872-2067(12)60754-2 Abstract ( 331 )   [Full Text(HTML)] () PDF (586KB) ( 737 )   A general and efficient catalytic system for Pd/C-catalyzed ligand-free aerobic Suzuki cross-coupling reactions was developed. The reaction tolerated a wide range of aryl bromides with a hydrophilic group or a hydrophobic group without any additives in water. Moreover, the catalytic system was successfully extended to the cross-couplings of heteroaryl halides with various arylboronic acids. The Pd/C catalyst could be reused three times without significant loss of catalytic activity.

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Boehmite nanoparticle catalyst for the one-pot multicomponent synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones under solvent-free conditions Ali Keivanloo, Mahdi Mirzaee, Mohammad Bakherad, Atena Soozani 2014, 35 (3):  362-367.  DOI: 10.1016/S1872-2067(12)60759-1 Abstract ( 313 )   [Full Text(HTML)] () PDF (478KB) ( 622 )   A simple, green, and efficient synthesis protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones using boehmite nanoparticles as catalyst was developed. It did not use any toxic metal catalysts or corrosive acidic reagents. The method gave good to excellent yields and has short reaction time, operational simplicity, and a recyclable catalyst.

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ZnAl2O4@SiO2 nanocomposite catalyst for the acetylation of alcohols, phenols and amines with acetic anhydride under solvent-free conditions Saeed Farhadi, Kosar Jahanara 2014, 35 (3):  368-375.  DOI: 10.1016/S1872-2067(12)60758-X Abstract ( 305 )   [Full Text(HTML)] () PDF (509KB) ( 951 )   A ZnAl2O4@SiO2 nanocomposite was prepared from metal nitrates and tetraethyl orthosilicate by the sol-gel process, and characterized by X-ray diffraction, Fourier transform infrared, transmission electron microscopy, and N2 adsorption-desorption measurements. The nanocomposite was tested as a heterogeneous catalyst for the acetylation of alcohols, phenols, and amines under solvent-free conditions. Under optimized conditions, efficient acetylation of these substrates with acetic anhydride over the ZnAl2O4@SiO2 nanocomposite was obtained. Acetylation of anilines and primary aliphatic amines proceeded rapidly at room temperature, while the reaction time was longer for the acetylation of alcohols and phenols, showing that an amine NH2 group can be selectively acetylated in the presence of alcoholic or phenolic OH groups. The catalyst can be reused without obvious loss of catalytic activity. The catalytic activity of the ZnAl2O4@SiO2 nanocomposite was higher than that of pure ZnAl2O4. The method gives high yields, and is clean, cost effective, compatible with substrates having other functional groups and it is suitable for practical organic synthesis.

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Ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles as new and green magnetically separable catalyst for 1,8-dioxodecahydroacridine synthesis Amir Khojastehnezhad, Mohammad Rahimizadeh, Hossein Eshghi, Farid Moeinpour, Mehdi Bakavoli 2014, 35 (3):  376-382.  DOI: 10.1016/S1872-2067(14)60001-2 Abstract ( 245 )   [Full Text(HTML)] () PDF (745KB) ( 910 )   A new magnetically separable catalyst consisting of ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles was prepared. The synthesized catalyst was characterized using vibrating sample magnetometry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. This new magnetic catalyst was shown to be an efficient heterogeneous catalyst for the synthesis of 1,8-dioxodecahydroacridines under solvent-free conditions. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.

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An electrode with Ni(Ⅱ) loaded analcime zeolite catalyst for the electrooxidation of methanol Seyed Naser Azizi, Shahram Ghasemi, Neda Salek Gilani 2014, 35 (3):  383-390.  DOI: 10.1016/S1872-2067(14)60002-4 Abstract ( 302 )   [Full Text(HTML)] () PDF (983KB) ( 729 )   There is a high overvoltage in the oxidation of methanol in fuel cells, and so modified electrodes are used to decrease it. A modified electrode that used Ni(Ⅱ) loaded analcime zeolite to catalyze the electrooxidation of methanol in alkaline solution was proposed. Analcime zeolite was synthesized by hydrothermal synthesis, and Ni(Ⅱ) ions were incorporated into the analcime structure, which was then mixed with carbon paste to prepare modified electrode. The electrocatalytic oxidation of methanol on the surface of the modified electrode in alkaline solution was investigated by cyclic voltammetry and chronoamperometry. The effects of the scan rate of the potential, concentration of methanol, and amount of zeolite were investigated. The rate constant for the catalytic reaction of methanol was 6×103 cm3 mol-1 s-1 from measurements using chronoamperometry. The proposed electrode significantly improved the electron transfer rate and decreased the overpotential for methanol oxidation.

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An efficient one-pot three-component synthesis of tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives using starch solution as catalyst Nourallah Hazeri, Malek Taher Maghsoodlou, Fatemeh Mir, Mehrnoosh Kangani, Hamideh Saravani, Ebrahim Molashahi 2014, 35 (3):  391-395.  DOI: 10.1016/S1872-2067(14)60003-6 Abstract ( 386 )   [Full Text(HTML)] () PDF (337KB) ( 1231 )   Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst. The use of a nontoxic and biodegradable catalyst, simple work-up procedure, and short reaction time are advantages of this method.

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Acidic ionic liquid-catalyzed esterification of oleic acid for biodiesel synthesis Ying Li, Shuanglan Hu, Jianhua Cheng, Wenyong Lou 2014, 35 (3):  396-406.  DOI: 10.1016/S1872-2067(14)60005-X Abstract ( 363 )   [Full Text(HTML)] () PDF (678KB) ( 984 )   Acidic ionic liquids (ILs) are used as environmentally-friendly and promising acid catalysts for biodiesel synthesis owing to their beneficial characteristics such as high catalytic activity, high selectivity, and ease of recycling. In this paper, seven different acidic ILs were examined as catalysts in the synthesis of biodiesel from the esterification of oleic acid with methanol. It was found that the stronger the acidity of the IL, the higher its esterification activity. The introduction of a SO3H group into the IL greatly increases its Brönsted acidity and results in a bifunctional nature of the ILs for use as either a catalyst or environmentally-friendly solution in the esterification reaction. All of these effects contribute to product formation. Of all the tested acidic ILs, 1-sulfobutyl-3-methylimidazoliumhydrosulfate ([BHSO3MIM]HSO4) exhibited the best catalytic performance. The [BHSO3MIM]HSO4-catalyzed esterification of oleic acid with methanol was systematically explored, and the reaction conditions were optimized using a response surface methodology. The optimum molar ratio of methanol to oleic acid, catalyst amount, reaction temperature, and reaction time were 4:1, 10% (based on the mass of oleic acid), 130 ℃, and 4 h, respectively, under these conditions, and a yield of methyl oleate (biodiesel) of 97.7% was achieved. Furthermore, [BHSO3MIM]HSO4 retained around 95.6% of its original catalytic activity after 10 successive reuses (4 h per period of use), showing excellent operational stability. In addition, the use of [BHSO3MIM]HSO4 for biodiesel synthesis from waste oils containing 72% of free fatty acids was examined, and yields as high as 94.9% after 6 h were obtained. Clearly, [BHSO3MIM]HSO4 shows considerable potential for the synthesis of biodiesel.

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Active oxygen-assisted NO-NO2 recycling and decomposition of surface oxygenated species on diesel soot with Pt/Ce0.6Zr0.4O2 catalyst Shuang Liu, Xiaodong Wu, Yu Lin, Min Li, Duan Weng 2014, 35 (3):  407-415.  DOI: 10.1016/S1872-2067(14)60004-8 Abstract ( 245 )   [Full Text(HTML)] () PDF (962KB) ( 586 )   A Pt/Ce0.6Zr0.4O2 catalyst was synthesized by impregnating a Ce0.6Zr0.4O2 support with Pt(NO3)2 solution. This material exhibits higher catalytic activity than Pt/Al2O3 for soot oxidation under loose contact conditions in both NO + O2 and O2 atmospheres. The results show that the pronounced activity of this catalyst is attributed to a synergistic effect arising from the combination of Pt and Ce0.6Zr0.4O2 solid solution, leading to a remarkable increase in the availability of active oxygen at temperatures as low as 450 ℃. The NO↔NO2 recycling efficiency is improved over Pt/Ce0.6Zr0.4O2 catalyst, enhancing the ability of the NO2-soot reaction to generate surface oxygenated complexes (SOCs) on the soot. More importantly, the catalytic oxidation of these SOCs can be accelerated with the participation of active oxygen from the CeO2-ZrO2 solid solution. As a result, during soot oxidation under NO + O2, the light-off temperature of the Pt/Ce0.6Zr0.4O2 catalyst is lowered by 34 ℃ than that of Pt/Al2O3 catalyst.

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The role of water in photocatalytic dissociation of methanol on rutile TiO2(110)-(1×1) Chenbiao Xu, Wenshao Yang, Qing Guo, Dongxu Dai, Maodu Chen, Xueming Yang 2014, 35 (3):  416-422.  DOI: 10.1016/S1872-2067(14)60006-1 Abstract ( 313 )   [Full Text(HTML)] () PDF (491KB) ( 609 )   We have performed a surface photocatalysis study of the molecularly adsorbed forms of methanol on a vacuum-annealed rutile TiO2(110)-(1×1) surface using temperature-programmed desorption both with and without coadsorbed water to investigate the effect of water and methanol on the photocatalytic dissociation of each other on rutile TiO2(110)-(1×1). Our experimental results show conclusively that methanol has no effect on photocatalytic water splitting with water covered rutile TiO2(110)-(1×1) surface. Further experimental results also show that water does not affect the process of photocatalytic methanol dissociation but does suppress photo-induced desorption of the formaldehyde product of methanol photocatalysis and can enhance the formation of the methyl formate product.

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Simultaneous and sensitive detection of dopamine and uric acid using a poly(L-methionine)/gold nanoparticle-modified glassy carbon electrode Reza Ojani, Jahan-Bakhsh Raoof, Ali Asghar Maleki, Saeid Safshekan 2014, 35 (3):  423-429.  DOI: 10.1016/S1872-2067(14)60022-X Abstract ( 265 )   [Full Text(HTML)] () PDF (1086KB) ( 494 )   A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine) (PMT)-modified glassy carbon electrode (GCE) to form a nano-Au/PMT composite-modified GCE (nano-Au/PMT/GCE). Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode. The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH = 7.00). Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0×10-8 to 10-6 mol/L for DA and 7.0×10-8 to 10-6 mol/L for UA. The detection limits were 3.7×10-8 mol/L for DA and 4.5×10-8 mol/L for UA at a signal-to-noise ratio of 3. According to our experimental results, nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.

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Species surface concentrations on a SAPO-34 catalyst exposed to a gas mixture Yasukazu Kobayashi, Yuxin Li, Yao Wang, Dezheng Wang 2014, 35 (3):  430-436.  DOI: 10.1016/S1872-2067(14)60007-3 Abstract ( 312 )   [Full Text(HTML)] () PDF (522KB) ( 470 )   The use of the Langmuir isotherm for competitive adsorption and the use of ideal adsorbed solution theory (IAST) for calculating the surface concentrations of adsorbed species on a SAPO-34 catalyst exposed to a gas mixture were compared with experimental measurements. Two binary mixtures, namely, methanol and dimethyl ether (DME) at 80 ℃ and DME and ethene at 25 ℃ were used. IAST gave good agreement in the whole range of experimental concentrations, while Langmuir theory only gave good agreement up to when one-third of the acid sites were covered and then showed increasingly large deviations with increased pressure, and it failed to capture the phenomenon that the concentration of an adsorbed species with a smaller saturation adsorption capacity would decrease with increased pressure. Thus, for reactions of gas mixtures whose components have different saturation adsorption capacities, Langmuir theory can only be used for the reaction kinetics when the surface concentrations are quite low, and IAST should be used when the surface concentrations are high.

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La(OH)3 and La2O2CO3 nanorod catalysts for Claisen-Schmidt condensation Fei Wang, Na Ta, Yong Li, Wenjie Shen 2014, 35 (3):  437-443.  DOI: 10.1016/S1872-2067(14)60008-5 Abstract ( 346 )   [Full Text(HTML)] () PDF (728KB) ( 807 )   La(OH)3 nanorods of 15 nm diameter and up to 700 nm long were synthesized using different pH values of the solution used in the hydrothermal synthesis. A more alkaline solution favored the formation of tiny La(OH)3 nuclei, which grew along the c-axis due to their anisotropic nature and led to the formation of rod-shaped crystals. Calcination of the La(OH)3 nanorods at 773 K gave La2O2CO3 nanorods. Their basic properties were correlated with their size. As the aspect ratio increased from 2 to 20, the basic sites increased from 0.08 to 0.24 mmol/g, which was due to a higher exposure of (110) planes. In the catalysis of the condensation reaction of benzaldehyde with acetophenone, the reaction rate was correlated with the number of La3+-O2- pairs on the exposed (110) facets of the La2O2CO3 nanorods.

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SiO2-Cu2O：An efficient and recyclable heterogeneous catalyst for N-benzylation of primary and secondary amines Manjulla Gupta, Satya Paul, Rajive Gupta 2014, 35 (3):  444-450.  DOI: 10.1016/S1872-2067(14)60009-7 Abstract ( 238 )   [Full Text(HTML)] () PDF (3008KB) ( 639 )   A mild, effective, and selective procedure is reported for the mono N-benzylation and N,N-dibenzylation of primary amines as well as mono N-benzylation of secondary amines using silica-supported copper(I) oxide in water. The silica-supported Cu2O was generated in situ by the reaction of Fehling solution and glucose at 100 ℃ onto activated silica. The catalyst was filtered, washed with water, and oven-dried, and was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and atomic absorption spectroscopy. The prepared Cu2O-SiO2 was found to be thermally stable up to 325 ℃. The copper was uniformly distributed onto the surface of the silica, and the mean particle diameter was 7 nm. The catalyst served as a selective heterogenous catalyst for the N-benzylation of primary and secondary amines. The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity. Various reaction solvents including water, acetonitrile, and toluene were screened for N-benzylation of amines, and the success of the aqueous system highlights the low environmental impact of the procedure.

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Author Index 2014, 35 (3):  451-451.  Abstract ( 90 )   [Full Text(HTML)] () PDF (271KB) ( 214 )