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Chinese Journal of Catalysis
2015, Vol. 36, No. 8
Online: 29 July 2015


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Yi and co-workers in their Article on pages 1175–1182 developed the Rh(III)-catalyzed direct C–H cyanation of diverse N-methoxybenzamides by employing N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) as an environmentally friendly and efficient cyanating reagent. The present reaction proceeds with good regioselectivity to deliver a variety of valuable ortho- cyanated N-methoxybenzamides with board substrate/functional group tolerance.

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Table of Contents for VOL.36 No.8 2015, 36 (8):  0-0.  Abstract ( 128 )   PDF (4266KB) ( 528 )

Review

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Metal nanoparticles immobilized on ion-exchange resins: A versatile and effective catalyst platform for sustainable chemistry Francesca Liguori, Carmen Moreno-Marrodan, Pierluigi Barbaro 2015, 36 (8):  1157-1169.  DOI: 10.1016/S1872-2067(15)60865-8 Abstract ( 370 )   [Full Text(HTML)] () PDF (841KB) ( 1516 )   This paper reviews the recent achievements in the immobilization of metal nanoparticles on ion-exchange resins and the related catalytic application. The focus is on the production processes for fine and commodity chemicals for which a low environmental impact has been demonstrated. The most significant papers that appeared in the literature from January 2010 to July 2014 have been covered. Their uses in unselective processes, bulk chemicals production, fuel cells components, as well as the use of metal-free ion-exchange resins in acid / base-catalysed reactions, were not included.

Communication

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Efficient enantioselective hydrogenation of quinolines catalyzed by conjugated microporous polymers with embedded chiral BINAP ligands Xu Wang, Jun Li, Shengmei Lu, Yan Liu, Can Li 2015, 36 (8):  1170-1174.  DOI: 10.1016/S1872-2067(15)60903-2 Abstract ( 254 )   [Full Text(HTML)] () PDF (801KB) ( 573 )   Chiral Ir complexes were successfully used in the asymmetric hydrogenation of olefins, ketones, and quinolines. However, almost all the catalytic systems could not tolerate a high catalyst loading because of the formation of an irreversible iridium dimer and trimer during the reaction. It is expected that higher catalytic activity may be achieved if the Ir-complexes were isolated in space. The development of conjugated microporous polymers (CMPs) gives the opportunity for the spatial separation of the complexes. A series of chiral CMPs based on the chiral (R)-BINAP ligand (BINAP-CMPs) with different surface areas were synthesized. The BINAP ligands were separately distributed in the framework and were three times more active than the homogeneous catalyst (TOF 340 h-1 VS 100 h-1) for the asymmetric hydrogenation of quinolines.

Articles

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Rh(III)-catalyzed direct C-H cyanation of N-methoxybenzamides using N-cyano-N-phenyl-p-toluenesulfonamide Siwei Zhang, Jie Zhou, Jingjing Shi, Min Wang, H. Eric Xu, Wei Yi 2015, 36 (8):  1175-1182.  DOI: 10.1016/S1872-2067(15)60872-5 Abstract ( 370 )   [Full Text(HTML)] () PDF (688KB) ( 644 )   A new method has been developed for the mild and efficient Rh(III)-catalyzed direct C-H cyanation of a diverse range of N-methoxybenzamides using N-cyano-N-phenyl-p-toluenesulfonamide as an environmentally friendly and efficient cyanating reagent. This new reaction proceeded with good regioselectivity to provide direct access to a wide variety of valuable ortho-cyanated N- methoxybenzamides with board substrate/functional group tolerance.

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Solvent engineering of spin-coating solutions for planar-structured high-efficiency perovskite solar cells Bing Cai, Wen-Hua Zhang, Jieshan Qiu 2015, 36 (8):  1183-1190.  DOI: 10.1016/S1872-2067(15)60929-9 Abstract ( 514 )   [Full Text(HTML)] () PDF (1285KB) ( 2275 )   Control of the morphology and coverage of high-quality perovskite films is the main issue affecting planar-structured perovskite solar cells fabricated by solution processing. In this work, the solvent engineering of mixed solutions for spin-coating uniform perovskite thin films was investigated in detail by adding different ratios of N,N-dimethylformamide (DMF) or γ-butyrolactone (GBL) to dimethyl sulfoxide (DMSO). The morphology and film thickness of the resulting perovskite films were found to be significantly altered. At 20%~40% (volume fraction) of N,N-dimethylformamide mixed with DMSO, micrometer scale grains and reduced grain boundaries were observed on the highly uniform perovskite thin films. The optimized planar-structured perovskite solar cells showed power conversion efficiency as high as 16.5% and a stabilized efficiency of 14.4% at a fixed forward bias of 0.88 V.

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Nano-sized NiLa2O4 spinel-NaBH4-mediated reduction of imines to secondary amines Ali Shiri, Faezeh Soleymanpour, Hossein Eshghi, Iman Khosravi 2015, 36 (8):  1191-1196.  DOI: 10.1016/S1872-2067(15)60921-4 Abstract ( 367 )   [Full Text(HTML)] () PDF (828KB) ( 751 )   Nano-sized NiLa2O4 spinel was produced by thermal decomposition of Ni-La compounds via a sol-gel method. The well-crystallized spinel structure was formed after calcination at 750 ℃. The physicochemical properties of the spinel were investigated using differential thermal analysis, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and particle size distribution analysis. The results show that the nanoparticles have regular shapes with well-defined crystal faces and consist of uniform quasi-spherical crystallites of average size 40 nm. The refined unit cell parameters are a = 3.861205 Å and c = 12.6793 Å. This new nano-sized NiLa2O4 spinel is an efficient heterogeneous catalyst for the selective conversion of imines to the corresponding secondary amines in the presence of NaBH4 as a reducing agent, in good to excellent yields. All the reactions were completely chemoselective at room temperature and had relatively short reaction times. Secondary amines with different aryl groups, including those bearing electron-withdrawing or electron-donating groups, were obtained under the optimum reaction conditions. The catalyst was readily recovered and was recycled four times with no significant loss of catalytic activity.

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Effect of pyrolysis conditions on nitrogen-doped ordered mesoporous carbon electrocatalysts Guifa Long, Kai Wan, Mingyao Liu, Xiaohua Li, Zhenxing Liang, Jinhua Piao 2015, 36 (8):  1197-1204.  DOI: 10.1016/S1872-2067(15)60912-3 Abstract ( 362 )   [Full Text(HTML)] () PDF (566KB) ( 811 )   Pt is the most effective and widely used electrocatalyst for the oxygen reduction reaction (ORR) in fuel cells; however, its scarcity and high cost pose a great challenge to the commercialization of the fuel cell technology. N-doped carbon materials have been regarded as one of the most promising Pt-alternative catalysts. In this work, the N-doped ordered mesoporous carbon was synthesized by the nanocasting method using SBA-15 as the template. The effect of the pyrolysis conditions (pyrolysis temperature, pyrolysis duration, and ramp rate) on this material was investigated. N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the intrinsic properties of the resultant materials. Cyclic voltammetry and rotating ring-disk electrode were used to investigate the electrochemical behavior for ORR in an alkaline medium. It was found that the resultant mesoporous carbon materials exhibit high electrical conductivity, high specific surface area, and unique pore structure. The pyrolysis temperature was the most important parameter in determining the thermodecomposition of the carbon precursor, and the microstructure, elemental composition, and chemical configuration of the resultant mesoporous carbon materials. To achieve reasonable electrocatalytic activity and selectivity, a high pyrolysis temperature above 800 ℃ is required for effective N doping to form active sites and for graphitization to facilitate charge transfer, whereas the pyrolysis duration and ramp rate have a much less significant effect. This indicates that both the surface composition/structure and consequent electrochemical properties are more dependent on the thermodynamics than the kinetics during the pyrolysis process. Finally, the optimal N-doped ordered mesoporous carbon catalyst showed superior electrochemical activity for ORR than the commercial Pt catalyst and is promising for fuel cell and metal-air battery applications.

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Oxidative desulfurization of dibenzothiophene catalyzed by peroxotungstate on functionalized MCM-41 materials using hydrogen peroxide as oxidant Dong Xie, Qihui He, Yangyang Su, Tongwei Wang, Renfu Xu, Baixing Hu 2015, 36 (8):  1205-1213.  DOI: 10.1016/S1872-2067(15)60897-X Abstract ( 333 )   [Full Text(HTML)] () PDF (935KB) ( 678 )   Catalysts play an important role in oxidative desulfurization, a promising process for producing cleaner fossil fuels for transport. A highly efficient catalyst, Q4-H2SeIV3W6, for the oxidative desulfurization of dibenzothiophene (DBT) was reported in 2011. To comprehensively evaluate this catalyst and better understand its recovery, two types of the catalyst were prepared by impregnating Q4-H2SeIV3W6 on MCM-41 and functionalized MCM-41 materials. In the oxidative desulfurization process catalyzed by these supported catalysts, the conversion of DBT reached 98.7%. The catalytic activities were excellent when Q4-H2SeIV3W6 was impregnated on functionalized MCM-41. The results showed that the supported catalysts had excellent reusability. In addition, a mechanism for the catalytic oxidative desulfurization was proposed.

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Direct dehydrogenation of isobutane to isobutene over carbon catalysts Yang Li, Zhongshen Zhang, Junhui Wang, Chunyan Ma, Hongling Yang, Zhengping Hao 2015, 36 (8):  1214-1222.  DOI: 10.1016/S1872-2067(15)60914-7 Abstract ( 484 )   [Full Text(HTML)] () PDF (956KB) ( 695 )   Various carbon materials were found to function as highly active catalysts for the direct dehydrogenation of isobutane without the addition of oxidizing gases (such as oxygen, carbon dioxide or nitrous oxide) or the deposition of metal particles. Among these materials, coconut shell activated carbon (CSAC) generated the highest isobutane conversion of 70%. It is notable that the CSAC catalyst exhibited a high degree of catalytic stability that was comparable to that of conventional catalysts and was able to maintain a selectivity for isobutene of approximately 76%. The most important factor with regard to the catalytic activity of both fresh and used carbon catalysts was determined to be the specific surface area of the material. These results are unique since they indicate that various carbon materials, including deposited coke, can behave as effective catalysts for the isobutane conversion reaction even without the presence of functional groups.

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Immobilization of cellulase onto MnO2 nanoparticles for bioethanol production by enhanced hydrolysis of agricultural waste Elsa Cherian, Mahendradas Dharmendirakumar, Gurunathan Baskar 2015, 36 (8):  1223-1229.  DOI: 10.1016/S1872-2067(15)60906-8 Abstract ( 284 )   [Full Text(HTML)] () PDF (689KB) ( 1098 )   Cellulase is an efficient enzymatic catalyst that hydrolyses cellulosic substances. The high costs associated with using enzymes for industrial applications can be reduced by immobilizing the cellulase. In the current study, cellulase produced by Aspergillus fumigatus JCF was immobilized onto MnO2 nanoparticles, which improve the activity of cellulase and offer a superior support. The surface characteristics of synthesized MnO2 nanoparticles and cellulase-bound MnO2 nanoparticles were investigated by scanning electron microscopy, and Fourier transform infrared spectroscopy was used to analyze the functional characteristics of the immobilized cellulase. The maximum cellulase binding efficiency was 75%. The properties of the immobilized cellulase, including activity, operational pH, temperature, thermal stability, and reusability were investigated and were found to be more stable than for the free enzyme. It was found that cellulase immobilized on MnO2 nanoparticles could be used to hydrolyze cellulosic substances over a broad range of temperature and pH. The results confirmed that cellulase immobilized on MnO2 nanoparticles was very efficient in terms of cellulolytic activity.

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TEMPO immobilized on polymer microspheres-catalyzed oxidation of cyclohexanol by molecular oxygen Baojiao Gao, Liqin Zhang, Tao Chen 2015, 36 (8):  1230-1236.  DOI: 10.1016/S1872-2067(15)60902-0 Abstract ( 304 )   [Full Text(HTML)] () PDF (615KB) ( 746 )   2,2,6,6-four methyl piperidine nitroxide (TEMPO) was bonded on crosslinked poly(glycidyl methacrylate) microspheres (CPGMA microspheres) by ring opening reactions between the epoxy group on the CPGMA microspheres and the hydroxyl group of 4-OH-TEMPO. The obtained heterogeneous TEMPO-immobilized polymeric (TEMPO/CPGMA) microspheres combined with a homogeneous co-catalyst Fe(NO3)3 was used in the oxidation of cyclohexanol by molecular oxygen. The catalytic property and catalytic mechanism were examined. This combination catalyst effectively catalyzed the oxidation of cyclohexanol by molecular oxygen to cyclohexanone as the only product. Both Fe3+ ion and NO3- ion in Fe(NO3)3 together played the role of co-catalyst. For this combination catalyst, under the conditions of 1:1 molar ratio of immobilized TEMPO to Fe(NO3)3, 55 ℃, ordinary pressure and with a suitable amount of this combination catalyst, the cyclohexanone yield was 44.1%, effectively transforming cyclohexanol to cyclohexanone under mild conditions.

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Synthesis, characterisation and activity of SBA-16 supported oxidation catalysts for CO conversion N. K. Renuka, K. Anas, C. U. Aniz 2015, 36 (8):  1237-1241.  DOI: 10.1016/S1872-2067(15)60894-4 Abstract ( 344 )   [Full Text(HTML)] () PDF (536KB) ( 639 )   V2O5, CeO2, and CuO were dispersed on rice husk derived SBA-16, and the CO oxidation activities of these systems were examined. The catalysts were characterised using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, temperature-programmed reduction, and diffuse reflectance ultraviolet spectroscopy. The CuO doped mesoporous silica was identified as a promising catalyst. More than 98% of CO conversion was achieved over the system.

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Oxidative dehydrogenation of ethane with CO2 over Cr supported on submicron ZSM-5 zeolite Yanhu Cheng, Fan Zhang, Yi Zhang, Changxi Miao, Weiming Hua, Yinghong Yue, Zi Gao 2015, 36 (8):  1242-1248.  DOI: 10.1016/S1872-2067(15)60893-2 Abstract ( 382 )   [Full Text(HTML)] () PDF (808KB) ( 1017 )   A series of submicron ZSM-5-supported chromium oxide catalysts were prepared and characterized by XRD, N2 adsorption, 27Al MAS NMR, SEM, XPS, laser Raman spectroscopy and diffuse reflectance UV-Vis spectroscopy. The catalytic performance of these materials during ethane dehydrogenation in the presence of CO2 was investigated. The catalysts exhibited both high activity and stability, with an ethane conversion of ~65% and ethylene yield of ~49% without any obvious deactivation following 50 h. Characterization results show that the excellent catalytic performance results from the high degree of dispersion of CrOx species on the submicron ZSM-5 surface. Both a high Si/Al ratio and the use of the Na-form of the ZSM-5 support were found to favor CrOx dispersion. The promotional effect of CO2 on the dehydrogenation reaction was quite evident and can be attributed to the reverse water-gas shift reaction.

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Efficient synthesis of 1,8-dioxo-octahydroxanthenes catalyzed by β-cyclodextrin grafted with butyl sulfonic acid in aqueous media Kai Gong, Hualan Wang, Shuxin Wang, Ying Wang, Jinghua Chen 2015, 36 (8):  1249-1255.  DOI: 10.1016/S1872-2067(15)60888-9 Abstract ( 315 )   [Full Text(HTML)] () PDF (580KB) ( 870 )   β-Cyclodextrin was functionalized with butyl sulfonic acid to give an efficient, eco-friendly catalyst for the synthesis of 1,8-dioxo-octahydroxanthenes via the one-pot condensation of aromatic aldehydes and active methylene carbonyl compounds in aqueous media. This new methodology offers several advantages such as excellent yields, short reaction time, a simple procedure and mild reaction conditions. Furthermore, the catalyst can be readily recovered and reused up to five times without a significant loss in its activity.

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Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3 Rui Yang, Haifeng Huang, Yijie Chen, Xixiong Zhang, Hanfeng Lu 2015, 36 (8):  1256-1262.  DOI: 10.1016/S1872-2067(15)60884-1 Abstract ( 254 )   [Full Text(HTML)] () PDF (908KB) ( 868 )   Cr-V/TiO2 catalysts with different Cr/V molar ratios for low-temperature selective catalytic reduction (SCR) of NO with NH3 were prepared by impregnation. The samples were characterized using X-ray diffraction, NH3 temperature-programmed desorption, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The results show that doping with Cr ions increased the amounts of weak and medium acid sites on the catalyst surface, as well as the low-temperature reductive capacity for high-valence V ions, and promoted the chemical adsorption of oxygen on the catalyst surface, which enhanced the rate of the SCR reaction. The catalyst with a Cr/V molar ratio of 0.2:0.8 and 10 wt% loading gave the largest amount of weak acid sites and the best NOx-removing performance, with a NOx conversion greater than 90% at 160-300 ℃. This catalyst had high stability in the presence of 0.01% SO2.

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Visible-light-induced photocatalytic performances of ZnO-CuO nanocomposites for degradation of 2,4-dichlorophenol E. D. Sherly, J. Judith Vijaya, L. John Kennedy 2015, 36 (8):  1263-1272.  DOI: 10.1016/S1872-2067(15)60886-5 Abstract ( 267 )   [Full Text(HTML)] () PDF (2660KB) ( 892 )   Nanostructured ZnO and CuO, and coupled oxides, i.e., ZnCu, Zn2Cu, and ZnCu2, with ZnO:CuO molar ratios of 1:1, 2:1, and 1:2, respectively, were successfully prepared through a simple, one-step, microwave-assisted urea-nitrate combustion synthesis, without the use of organic solvents or surfactants. The prepared samples were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The optical absorption of ZnO extended into the visible region after CuO loading. The photocatalytic activities of ZnO, CuO, and the coupled oxides were evaluated based on photodegradation of 2,4-dichlorophenol under visible-light irradiation. The coupled metal oxide Zn2Cu showed the best photocatalytic activity; this was mainly attributed to the extended photoresponsive range and the increased charge separation rate in the nanocomposite. The photocatalytic degradation process obeyed pseudo-first-order kinetics. The results suggest that the coupled metal oxide Zn2Cu has potential applications as an efficient catalytic material with high efficiency and recyclability for the photocatalytic degradation of organic pollutants in aqueous solution under visible-light irradiation.

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A nanocomposite electrocatalyst for the electro-oxidation of isoproterenol and its application as a sensor Mohammad Mazloum-Ardakani, Mohammad Ali Sheikh-Mohseni, Bibi-Fatemeh Mirjalili, Roya Ahmadi, Mohammad Ali Mirhoseini 2015, 36 (8):  1273-1279.  DOI: 10.1016/S1872-2067(15)60918-4 Abstract ( 213 )   [Full Text(HTML)] () PDF (592KB) ( 638 )   A novel nanocomposite (GCE/AuNP-DAT) was fabricated via the self-assembly of a thiophenol derivative (3,4-dihydroxyphenyl-azo-2-thiophenol, DAT) on a gold nanoparticle (AuNP)-modified glassy carbon electrode (GCE). This novel modified electrode was investigated using cyclic voltammetry, and the electrode was applied for the electrocatalysis of isoproterenol (IP). The electrocatalytic activity of this nanocomposite was studied, and the reaction mechanism and catalytic rate constant were determined for IP. The GCE/AuNP-DAT did not show any electrocatalytic activity for the oxidation of uric acid, and the oxidation signal for IP was therefore not affected by the presence of uric acid at this electrode; any interference from uric acid in the detection of IP was eliminated by the modified electrode. This electrode was applied as a sensor, and differential pulse voltammetry data obtained using this sensor exhibited a linear dynamic range of 1-1500 μmol/L and a detection limit of 0.46 μmol/L for IP.

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Synthesis and application of magnetically recyclable nanocatalyst Fe3O4@Nico@Cu in the reduction of azo dyes Md. Amir, U. Kurtan, A. Baykal 2015, 36 (8):  1280-1286.  DOI: 10.1016/S1872-2067(15)60879-8 Abstract ( 185 )   [Full Text(HTML)] () PDF (673KB) ( 913 )   A novel method for synthesizing magnetically recyclable nanocatalyst Fe3O4@Nico@Cu (Nico = nicotinic acid) was introduced. The structural, morphological, and magnetic properties of the nanocatalyst were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometry. Finally, Fe3O4@Nico@Cu was examined toward the hydrogenation of azo dyes methyl orange, methylene blue, eosin Y, and rhodamine B. The nanocatalyst showed excellent reusability properties that remained unchanged after several catalytic cycles. Therefore, the current findings show the potential of the prepared Fe3O4@Nico@Cu nanocatalyst as a candidate for application in the purification of organic aqueous pollutants for wastewater treatment.

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Potassium poisoning of titania supported deNOx catalysts: Preservation of vanadia and sacrifice of tungsten oxide Changming Chen, Xiaodong Wu, Wenchao Yu, Yuxi Gao, Duan Weng, Lei Shi, Chunlei Geng 2015, 36 (8):  1287-1294.  DOI: 10.1016/S1872-2067(15)60881-6 Abstract ( 272 )   [Full Text(HTML)] () PDF (507KB) ( 632 )   V2O5-WO3/TiO2 catalysts were prepared by a wet impregnation method, and the deactivation by KCl of their catalytic activity for selective catalytic reduction of NOx by NH3 (NH3-SCR) was investigated. The fresh and poisoned catalysts were characterized by inductively coupled plasma (ICP), N2 adsorption, Raman spectroscopy, H2 temperature-programmed reduction, IR spectroscopy of adsorbed NH3, and NH3 oxidation. Vanadia species, which are the active sites for the SCR reaction, were turned into inert potassium vanadate, but they were partially maintained on the catalyst at a high vanadia loading. Tungsten oxide acts as a sacrificial agent that reacts with potassium to form potassium tungstate in addition to its roles in increasing the surface acidity of the catalyst and facilitating the dispersion of vanadia. The V2O5-WO3/TiO2 catalyst at a high vanadia loading exhibited the best resistance to alkali poisoning.

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The effect of P modification on the acidity of HZSM-5 and P-HZSM-5/CuO-ZnO-Al2O3 mixed catalysts for hydrogen production by dimethyl ether steam reforming Jianhui Lü, Shuang Zhou, Kui Ma, Ming Meng, Ye Tian 2015, 36 (8):  1295-1303.  DOI: 10.1016/S1872-2067(15)60883-X Abstract ( 277 )   [Full Text(HTML)] () PDF (3064KB) ( 756 )   Dimethyl ether steam reforming (DME SR) was catalyzed by a CuO-ZnO-Al2O3 (CuZnAlO) catalyst mixed with P-modified HZSM-5 for the production of H2. The effect of P modification on the acidity and activity of the P-HZSM-5/CuZnAlO mixed catalyst for DME SR was investigated. P-HZSM-5/CuZnAlO gave a higher CO2 selectivity and also higher stability during DME SR compared to the mixed catalyst with HZSM-5. N2 desorption, X-ray diffraction, temperature-programmed oxidation (TPO), NH3 temperature-programmed desorption (NH3-TPD), Fourier transform infrared spectroscopy (FT-IR), and solid-state 31P magic angle spinning nuclear magnetic resonance (31P MAS NMR) were used for catalyst characterization. NH3-TPD results showed that both the acid quantity and strength of HZSM-5 were significantly changed after P modification. With increased P content, the density of strong acid sites decreased, while the weak acid sites changed little. TPO results indicated that catalyst deactivation was mainly caused by the deposition of coke. The catalyst with 5% P exhibited much better stability than the parent HZSM-5 due to the disappearance of strong acid sites after P modification. The FT-IR spectra of pyridine adsorption clearly revealed that with increased P content, there was an obvious decrease of Lewis acid sites and slight decrease of Brönsted acid sites. From the results of 31P MAS NMR, NH3-TPD and FT-IR of adsorbed pyridine, a description of the effect of phosphorus modification on HZSM-5 was proposed.

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Preparation of crown ether complexing highly active double metal cyanide catalysts and copolymerization of CO2 and propylene oxide Min Zhang, Yong Yang, Liban Chen 2015, 36 (8):  1304-1311.  DOI: 10.1016/S1872-2067(15)60868-3 Abstract ( 311 )   [Full Text(HTML)] () PDF (1288KB) ( 712 )   Double metal cyanide (DMC) catalysts are generally prepared by coprecipitation of potassium hexacyanocobaltate(III) with zinc chloride followed by complexation with tert-butanol, and these materials have been used for several decades in the copolymerization of CO2 and epoxides. However, the catalytic efficiency of DMC catalysts can be adversely affected by the presence of excess K+, and the preparation of these catalysts can therefore become complicated and time-consuming because of the multiple washing and centrifugation stages required for the removal of the excess K+. In this study, 18-crown-6 ether was used as an effective co-complexing agent for the removal of K+. A series of DMCs containing 18-crown-6 were prepared with different quantities of the crown ether and different washing times. The resulting crown ether-complexing catalysts (CDMCs) and DMC catalysts without crown ether were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis-IR and X-ray diffraction. These characterization results showed that the inclusion of 18-crown-6 allowed for the formation of uniform and highly dispersed CDMC catalysts. In contrast, the DMC catalysts prepared in the absence of 18-crown-6 became uneven and delaminated during the purification by centrifugation, with high- and low-density portions of the material forming on the bottom and top of the catalyst cakes, respectively. The inclusion of 18-crown-6 not only trapped K+ but also participated in the complexion process. The complexion of tert-BuOH and 18-crown-6 led to a less crystalline form of the CDMC catalyst. Elemental analysis revealed that CDMC1 contained 1.2% K+. The copolymer was obtained by the copolymerization of CO2 with propylene oxide using CDMC3 catalyst, which was superior to the copolymer prepared using DMC1. CDMC3 was as active as DMC2 prepared without the crown ether but with seven washing steps. A hypothetical two-stage catalytic mechanism was proposed.

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Adsorption states of typical intermediates on Ag/Al2O3 catalyst mployed in the selective catalytic reduction of NOx by ethanol Hua Deng, Yunbo Yu, Hong He 2015, 36 (8):  1312-1320.  DOI: 10.1016/S1872-2067(15)60873-7 Abstract ( 348 )   [Full Text(HTML)] () PDF (945KB) ( 598 )   The adsorption of ethanol and important intermediates onto Ag/Al2O3 catalyst employed in the selective catalytic reduction of NOx by ethanol was simulated by density functional theory. Considering the interaction between Ag metal and Al2O3 support, typical Ag-O-Al entities, i.e., Ag-O-Altetra and Ag-O-Alocta, (tetra = tetrahedral and octa = octahedral refer to the coordination sites of Al), were selected as potential adsorption sites on the surface of the catalyst. Ethanol, and enolic and isocyanate species were preferentially adsorbed and activated by Ag-O-Altetra entities rather than by Ag-O-Alocta entities. The strong Lewis acidity of Altetra in the Ag-O-Altetra entity was very important, enabling the entity to accept an electron via forward donation from either the C-O σ bond in ethanol or the N-C σ bond in the -NCO species. Moreover, the hybridization of the Ag and Al orbitals was critical for electron back donation from the Ag-O-Altetra entity to the C-C π bond in the enolic species or N-C π bond in the -NCO species. The significant activation of the N-C bond in -NCO on the Ag-O-Altetra sites facilitated cleavage of -NCO to form N2. Thus, we can conclude that the acidity of the Al site and the interaction between Ag and Al play key roles in the selective catalytic reduction of NOx by ethanol over Ag/Al2O3.

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Facet-dependent performance of Cu2O nanocrystal for photocatalytic reduction of Cr(VI) Bang Qin, Yubao Zhao, Hui Li, Liang Qiu, Zao Fan 2015, 36 (8):  1321-1325.  DOI: 10.1016/S1872-2067(15)60877-4 Abstract ( 352 )   [Full Text(HTML)] () PDF (642KB) ( 597 )   Cu2O octahedrons, rhombic dodecahedrons and cubes were prepared and evaluated for the reduction of hexavalent chromium under visible light irradiation. The specific activity of Cu2O with different crystal planes followed the order {111} > {110} > {100}. The surface capping ligands of octahedral and rhombic dodecahedral Cu2O have no blocking effect on their photocatalytic performance.

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Bioelectricity-generating behavior of a chemically modified carbon black anode in microbial fuel cells Xinhong Peng, Xizhang Chu, Wei Liu, Shenghui Wang, Yi Zou, Xiaonan Wang 2015, 36 (8):  1326-1332.  DOI: 10.1016/S1872-2067(15)60880-4 Abstract ( 201 )   [Full Text(HTML)] () PDF (642KB) ( 604 )   The poor stability of the current output in microbial fuel cells (MFCs) inhibits its development and application on a large scale. In this work, a carbon black (CB) MFC anode was chemically activated using HNO3 and KOH as pretreatment agents at low temperature, and further modification was made by Fe3O4 addition to the host CB matrix. The enhanced anodic capacitance contributes to a steady power output with neither overshoot nor undershoot below 1.1 F/cm2. This resulted from the introduction of oxygen(nitrogen)-associated functionalities and the improvement of the surface wettability by the activation treatment. The chemical modification of a CB anode provides a feasible way to optimize power production and anodic capacitance in MFCs.

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Effect of Y on improving the thermal stability of MnOx-CeO2 catalysts for diesel soot oxidation Hailong Zhang, Jianli Wang, Yi Cao, Yijing Wang, Maochu Gong, Yaoqiang Chen 2015, 36 (8):  1333-1341.  DOI: 10.1016/S1872-2067(15)60867-1 Abstract ( 289 )   [Full Text(HTML)] () PDF (619KB) ( 672 )   A series of MnOx-CeO2-Y2O3 catalysts with different Y loadings (0, 1, 3, 6, and 10 wt%) were prepared by a co-precipitation method and investigated for NOx-assisted soot oxidation. The thermal stabilities of these catalysts were evaluated by treating them at 800 ℃ for 12 h under dry air flow. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, Raman spectroscopy, H2 temperature-programmed reduction, oxygen storage capacity, NO temperature- programmed oxidation, X-ray photoelectron spectroscopy, and soot temperature-programmed oxidation. The addition of Y led to decreased BET surface areas and poor low-temperature reduction abilities and oxygen storage capacities, which affected NO and soot oxidation activities. However, after aging, the doping of Y had effectively enhanced the stability of the catalytic activities for NO and soot oxidations, where the addition of 6%-10% Y achieved the optimum result because the maximal soot oxidation rate temperature was increased by only 34-35 ℃. Additionally, the catalytic activity and deactivation of MnOx-CeO2-containing catalysts were closely related to the presence of Mn4+ and oxygen species on the surface.

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Selective oxidation of sulfurs and oxidation desulfurization of model oil by 12-tungstophosphoric acid on cobalt-ferrite nanoparticles as magnetically recoverable catalyst Ezzat Rafiee, Nasibeh Rahpeyma 2015, 36 (8):  1342-1349.  DOI: 10.1016/S1872-2067(15)60862-2 Abstract ( 199 )   [Full Text(HTML)] () PDF (623KB) ( 735 )   Silica-coated CoFe2O4 nanoparticles were prepared and used as a support for the immobilization of 12-tungstophosphoric acid, to produce a new magnetically separable catalyst. This catalyst was characterized using X-ray diffraction, wavelength-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser particle size analysis, and vibrating sample magnetometry. The catalyst showed high activity in the selective oxidation of thioethers and thiophenes to the corresponding sulfones under mild conditions. The catalytic activity of the nanocatalyst in the oxidative desulfurization of model oil was investigated. The effect of nitrogen-containing compounds on sulfur removal from the model oil was also evaluated. The catalyst showed high activity in the oxidative desulfurization of diesel. The catalyst can be readily isolated from the oxidation system using an external magnet and no obvious loss of activity was observed when the catalyst was reused in four consecutive runs.

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Facile solvothermal post-treatment to improve hydrothermal stability of mesoporous SBA-15 zeolite Chenglong Zou, Guanyu Sha, Haifang Gu, Yao Huang, Guoxing Niu 2015, 36 (8):  1350-1357.  DOI: 10.1016/S1872-2067(15)60857-9 Abstract ( 400 )   [Full Text(HTML)] () PDF (1355KB) ( 676 )   A simple and effective approach is demonstrated to improve the hydrothermal stability of mesoporous SBA-15 zeolite via a post-synthesis treatment of organic solvents, such as cyclohexane, toluene and n-butanol, at 157 or 190 ℃ for 6-24 h. After hydrothermal treatment at 800 ℃ for 12 h in 100% steam, the treated SBA-15 retained a well-ordered mesostructure, and retained high surface areas of 192-281 m2/g. SBA-15 zeolite treated by cyclohexane at 190 ℃ for 24 h showed the highest hydrothermal stability. The stabilization mechanism suggests that the solvothermal treatment has a significant promoting effect on dehydrating Si-OH groups in silica walls to form stable Si(OSi)4 from Si(OSi)2(OH)2 or Si(OSi)3OH groups. As a result, the wall defects after solvothermal treatment decrease, and the stability of silica is improved remarkably. This promoting effect strongly depends on the solvent properties, treatment temperature, and precursors of SBA-15 zeolite. The treatment by a nonpolar and low boiling point organic solvent displays the highest promoting effect on the calcined SBA-15 zeolite. This approach is simple, has low energy consumption and has potential application in the laboratory and for industry to prepare hydrothermally stable well-ordered mesoporous SBA-15 zeolite.

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Bimetallic synergistic Au/CuO-hydroxyapatite catalyst for aerobic oxidation of alcohols Tao Tian, Ying Liu, Xungao Zhang 2015, 36 (8):  1358-1364.  DOI: 10.1016/S1872-2067(15)60854-3 Abstract ( 328 )   [Full Text(HTML)] () PDF (1242KB) ( 744 )   A catalyst consisting of Au supported on copper oxide-modified hydroxyapatite (Au/CuO-HAP) was prepared using a homogeneous deposition-precipitation method. The catalyst was characterized using atomic absorption spectrometry, N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic performance in liquid-phase aerobic oxidation of alcohols was investigated. The catalytic activity and benzaldehyde selectivity in benzyl alcohol oxidation with the bimetallic Au/CuO-HAP catalyst were significantly better than those with monometallic Au/HAP and CuO-HAP catalysts. The conversion of benzyl alcohol and selectivity for benzaldehyde at 120 ℃ for 1.5 h under aerobic oxidation conditions were 99.7% and 98.4%, respectively. Various aromatic alcohols were selectively converted to their corresponding aldehydes or ketones over Au/CuO-HAP. The Au/CuO-HAP catalyst could be reused at least four times without loss of activity.

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Synthesis, characterization, and application of silica supported ionic liquid as catalyst for reductive amination of cyclohexanone with formic acid and triethyl amine as hydrogen source Ashif H. Tamboli, Avinash A. Chaugule, Faheem A. Sheikh, Wook-Jin Chung, Hern Kim 2015, 36 (8):  1365-1371.  DOI: 10.1016/S1872-2067(15)60848-8 Abstract ( 275 )   [Full Text(HTML)] () PDF (483KB) ( 954 )   A silica supported ionic liquid was synthesized and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and thermogravimetric analysis. All these techniques, especially SEM results indicated the presence of well-defined spherical particles having diameters larger than the pristine silica particles, confirming the successful immobilization of the ionic liquid. The prepared silica supported ionic liquid was used in the reductive amination of cyclohexanone under different conditions with different azeotropic mixtures of formic acid and triethyl amine as a hydrogen source. The catalyst showed efficient catalytic performance and excellent yields of N-cyclohexyl amine derivatives in the range of 58% to 84% at 30 ℃. After completion of the reaction, the catalyst was easily recovered by simple filtration and reused for another five cycles without any significant impact on product yields. The obtained catalytic performance indicates that the present catalyst is green, very active, and reusable for the reductive amination of cyclohexanone.

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Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes Ali Nakhaei Pour, Elham Hosaini, Mohammad Izadyar, Mohammad Reza Housaindokht 2015, 36 (8):  1372-1378.  DOI: 10.1016/S1872-2067(15)60840-3 Abstract ( 271 )   [Full Text(HTML)] () PDF (703KB) ( 727 )   The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reaction temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage.

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Efficient solvent-free synthesis of pyridopyrazine and quinoxaline derivatives using copper-DiAmSar complex anchored on SBA-15 as a reusable catalyst Marzieh Mohammadi, Ghasem Rezanejade Bardajee, Nader Noroozi Pesyan 2015, 36 (8):  1379-1386.  DOI: 10.1016/S1872-2067(15)60845-2 Abstract ( 352 )   [Full Text(HTML)] () PDF (655KB) ( 665 )   A catalytic system comprising mesoporous silica functionalized with Cu(II)-DiAmSar was synthesized. This was demonstrated as an efficient heterogeneous catalyst for the synthesis of biologically useful pyridopyrazine and quinoxaline heterocycles under solvent-free conditions. X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption, Fourtier transformation infrared spectroscopy, and thermogravimetric analysis were used to characterize the catalyst and investigate the texture of SBA-15 during the grafting process.

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Easily prepared water soluble Pd-NHC complex as an efficient, phosphine-free palladium catalyst for the Sonogashira reaction Chunyan Zhang, Jianhua Liu, Chungu Xia 2015, 36 (8):  1387-1391.  DOI: 10.1016/S1872-2067(15)60843-9 Abstract ( 303 )   [Full Text(HTML)] () PDF (512KB) ( 630 )   A water soluble Pd-NHC complex was prepared and its catalytic activity in the Sonogashira reaction of terminal alkynes and aryl iodides using water as solvent under phosphine-free conditions was shown. This gives an efficient approach to diarylalkynes. The water soluble Pd-NHC complex can be easily recovered by extraction of the reaction solution and it was reused four times with only a slight loss of catalytic activity.

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Methanol to hydrocarbons reaction over HZSM-22 and SAPO-11: Effect of catalyst acid strength on reaction and deactivation mechanism Jinbang Wang, Jinzhe Li, Shutao Xu, Yuchun Zhi, Yingxu Wei, Yanli He, Jingrun Chen, Mozhi Zhang, Quanyi Wang, Wenna Zhang, Xinqiang Wu, Xinwen Guo, Zhongmin Liu 2015, 36 (8):  1392-1402.  DOI: 10.1016/S1872-2067(15)60953-6 Abstract ( 341 )   [Full Text(HTML)] () PDF (977KB) ( 773 )   The conversion of methanol to hydrocarbons has been investigated over HZSM-22 and SAPO-11. Both of these catalysts possess one-dimensional 10-ring channels, but have different acidic strengths. Comparison studies and 12C/13C isotopic switching experiments were conducted to evaluate the influence of the acidic strength of the catalyst on the conversion of methanol, as well as its deactivation mechanism. Although the conversion of methanol proceeded via an alkene methylation-cracking pathway over both catalysts, the acidity of the catalysts had a significant impact on the conversion and product distribution of these reactions. The stability of the catalysts varied with temperature. The catalysts were deactivated at high temperature by the deposition of graphitic coke on their outer surface. Deactivation also occurred at low temperatures a result that the pores of the catalyst were blocked by polyaromatic compounds. The co-reaction of 13C-methanol and 12C-1-butene confirmed the importance of the acidity of the catalyst on the distribution of the hydrocarbon products.