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Chinese Journal of Catalysis
2013, Vol. 34, No. 7
Online: 16 July 2013


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By ball milling carbon nitride (C₃N₄) and ammonia borane (NH₃BH₃, AB), the AB-C₃N₄ system was successfully synthesized, as described by Zhang and coworkers in the Article on pages 1303–1311. The dehydrogenation temperature of C₃N₄-modified ammonia borane was reduced to lower region with depression of byproduct and shorter induction period compared with pristine ammonia borane. Thus, it is expected that the C₃N₄-modified ammonia borane can be used as a hydrogen storage material for the hydrogen fuel car in the future.

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Table of Contents for Vol. 34 No. 7 2013, 34 (7):  0-0.  Abstract ( 248 )   PDF (1874KB) ( 522 )

Reviews

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Progress in carbon monoxide oxidation over nanosized Ag catalysts ZHANG Xiaodong, QU Zhenping, YU Fangli, WANG Yi 2013, 34 (7):  1277-1290.  DOI: 10.1016/S1872-2067(12)60610-X Abstract ( 744 )   [Full Text(HTML)] () PDF (1042KB) ( 1144 )   Nanosized Ag catalysts have attracted much attention because of their unique catalytic properties for various reactions, in particular for CO oxidation at low temperatures. Recently, Ag catalysts displaying high catalytic activities and reaction stabilities, and good application prospects in the elimination of CO, even at ambient temperature, have been developed. In this review, combined with our group’s research, the different influencing factors such as the preparation method, support, pretreatment conditions, second component, other atmosphere, and reaction mechanisms are discussed in detail and summarized.

Communications

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Tuning the catalytic performance of carbon nanotubes by tuning the conjugation between the π orbitals of carbon nanotubes and the active oxygenic functional groups DU Yujue, LI Zhenhua, FAN Kangnian 2013, 34 (7):  1291-1296.  DOI: 10.1016/S1872-2067(12)60627-5 Abstract ( 511 )   [Full Text(HTML)] () PDF (528KB) ( 657 )   Periodic density functional theory calculations were used to systematically investigate the origin of the catalytic activity of carbon nanotubes (CNTs) and ways to improve the catalytic performance of CNTs for the oxidative dehydrogenation of propane. Detailed characterizations of the geometric and electronic structure of the active oxygenic functional groups (CO groups) were presented. The results reveal that the catalytic performance of CNTs can be tuned by tuning the conjugation between CNT π orbitals and the orbitals of the active CO groups. Through conjugation, CNTs act as an electron reservoir to donate or accept electrons from the CO group. We found that CO groups with a negative charge have higher C-H bond activation activity but lead to a more stable i-propoxide intermediate, which inhibits the formation of propene, while positively charged CO groups have the opposite effect. The balance between the activities of the two C-H activation steps can be obtained by tuning the charge of the CO group. This study increases the understanding of the origin of the activity of CNT catalysts at the microscopic scale and gives guidance for the preparation of high-performance CNT catalysts.

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Selective oxidation of toluene using surface-modified vanadium oxide nanobelts LI Xuan, YE Shuang, ZHAO Jianbo, LI Lei, PENG Luming, DING Weiping 2013, 34 (7):  1297-1302.  DOI: 10.1016/S1872-2067(12)60619-6 Abstract ( 350 )   [Full Text(HTML)] () PDF (740KB) ( 993 )   Vanadium oxide nanobelts were synthesized using a sonochemical-hydrothermal method. Hexadecylphosphonic acid (HDPA) was introduced onto the surfaces of the nanobelts and bulk vanadium oxide to tune their catalytic properties; these properties were tested using gas-phase oxidation of toluene. The catalytic activity of the vanadium oxide nanobelts was higher than that of the bulk oxide as a result of the higher lattice oxygen activity of the nanobelts. Doping with HDPA, tuning the lattice oxygen activity, and blocking unselective sites led to both higher activity and selectivities for benzaldehyde and benzoic acid on nanobelt-like vanadium oxides, whereas led to lower activity but higher selectivities for benzaldehyde and benzoic acid on bulk vanadium oxides.

Articles

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Effects of graphitic carbon nitride on the dehydrogenation of ammonia borane ZHANG Jing, HE Teng, LIU Bin, LIU Lin, ZHAO Zelun, HU Daqiang, JU Xiaohua, WU Guotao, CHEN Ping 2013, 34 (7):  1303-1311.  DOI: 10.1016/S1872-2067(12)60566-X Abstract ( 639 )   [Full Text(HTML)] () PDF (699KB) ( 713 )   By ball milling carbon nitride (C3N4) and ammonia borane (AB), the AB-C3N4 system was successfully synthesized. It is shown that the dehydrogenation temperature of the AB-C3N4 system was obviously decreased. However, the concentration of byproduct ammonia was much higher than that of pristine AB. Thus, LiBH4-modified C3N4 (LC3N4) was produced and employed to synthesize a AB-LC3N4 system. The dehydrogenation of the AB-LC3N4 system was investigated using X-ray diffraction, temperature-programmed desorption-mass spectrometry, thermogravimetry-differential thermal analysis, and nuclear magnetic resonance. The results show that the dehydrogenation temperatures of the AB-LC3N4 systems were reduced to a lower region compared with pristine AB. Moreover, byproduct borazine and the induction period were significantly suppressed. After LiBH4 modification on C3N4, the other byproduct ammonia was also reduced in the dehydrogenation process. Dynamic analysis and NMR characterization results show that the decomposition mechanism of AB-LC3N4 still follows the self-decomposition of AB, which is induced by the formation of NH3BH2NH3BH4.

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Controlling the phase transformations and performance of iron-based catalysts in the Fischer-Tropsch synthesis GAO Fangfang, WANG Hong, QING Ming, YANG Yong, LI Yongwang 2013, 34 (7):  1312-1325.  DOI: 10.1016/S1872-2067(12)60562-2 Abstract ( 735 )   [Full Text(HTML)] () PDF (769KB) ( 690 )   The phase transformations of a series of iron-based models of the catalysts used in the Fischer-Tropsch synthesis (FTS) were controlled using a combination of deep reduction followed by partial carburization. The catalysts were pretreated under a variety of different conditions and their performance in the FTS subsequently tested in a fixed-bed reactor. The physiochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Mössbauer effect spectroscopy (MES), H2 temperature-programmed desorption (TPD), and laser Raman spectroscopy (LRS) before and after the reaction. The results indicated that the catalysts consisted predominately of α-Fe particles following the H2 reduction. The size of the crystals and the stability of the catalysts increased with increasing reduction temperature. The carburization process mainly occurred on the surface of the α-Fe particles, and the rate of the carburization process could be effectively controlled using C2H4. Compared with the catalysts activated with H2 or syngas, the catalysts initially activated with H2 followed by C2H4 exhibited better performance in the FTS.

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Nickel(II) complex anchored on MCM-41 for the epoxidation of styrene by oxygen YANG Gang, CHEN Xing, WANG Xiaoli, XING Weihong, XU Nanping 2013, 34 (7):  1326-1332.  DOI: 10.1016/S1872-2067(12)60568-3 Abstract ( 454 )   [Full Text(HTML)] () PDF (658KB) ( 733 )   A heterogeneous catalyst, MCM-41-Ni, was synthesized by anchoring a nickel(II) Schiff base complex onto amino-modified MCM-41. The catalyst was characterized by small angle X-ray diffraction, nitrogen adsorption, infrared spectroscopy, thermal gravimetric analysis, inductively coupled plasma and C, H, N elemental analysis, and transmission electron microscopy. MCM-41-Ni showed excellent catalytic activity for the epoxidation of styrene with O2 as oxidant with high styrene conversion (95.2%) and epoxide selectivity (66.7%). The influence of reaction temperature, catalyst amount, solvent, and reaction time was studied. MCM-41-Ni showed good recyclability and can be reused four times.

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Electrocatalytic measurement of methionine concentration with a carbon nanotube paste electrode modified with benzoylferrocene Hadi BEITOLLAHI, Alireza MOHADESI, Farzaneh GHORBANI, Hassan KARIMI MALEH, Mehdi BAGHAYERI, Rahman HOSSEINZADEH 2013, 34 (7):  1333-1338.  DOI: 10.1016/S1872-2067(12)60582-8 Abstract ( 395 )   [Full Text(HTML)] () PDF (310KB) ( 628 )   A benzoylferrocene modified multi-wall carbon nanotube paste electrode for the measurement of methionine (MET) concentration is described. MET electrochemical response characteristics of the modified electrode in a phosphate buffer solution of pH 7.0 were investigated by cyclic voltammetry, square wave voltammetry, and chronoamperometry. Under optimized conditions, the square wave voltammetric peak current of MET increased linearly with MET concentration in the range of 1.0 × 10-7 to 2.0 ×10-4 mol/L. The detection limit was 58.0 nmol/L MET. The diffusion coefficient (D = 5.62 × 10-6 cm2/s) and electron transfer coefficient (α = 0.4) for MET oxidation were also determined. The sensor was successfully applied for the measurement of MET concentration in human urine.

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Enzymatic resolution of epichlorohydrin catalyzed by whole cells in an organic solvent/buffer biphasic system ZOU Shuping, YAN Haiwei, HU Zhongce, ZHENG Yuguo 2013, 34 (7):  1339-1347.  DOI: 10.1016/S1872-2067(12)60576-2 Abstract ( 517 )   [Full Text(HTML)] () PDF (503KB) ( 834 )   The biocatalytic resolution of (R,S)-epichlorohydrin to (R)-epichlorohydrin by whole cells from a recombinant Escherichia coli BL21(ED3) expressing epoxide hydrolase activity in a series of organic solvent/buffer biphasic systems was studied. Isooctane was found to be the best organic solvent. The optimum volume ratio of the organic phase to the aqueous phase, reaction temperature, pH, substrate concentration, cell concentration, and reaction time were 7:3, 30 ℃, 8.0, 574 mmol/L, 0.07 g/ml wet cells, and 45 min, respectively. Under the optimized conditions, a yield of 37.5% with 99.3% ee and an average productivity of 0.286 mol/(L·h) were obtained in a stirred reactor (1-L scale). Thus, the bioconversion was more efficient in the isooctane/buffer biphasic system than that in a monophasic aqueous system, where the substrate concentration and the average productivity of (R)-epichlorohydrin were improved by 55.2% and 98.6%, respectively.

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Effect of SAPO-34 molecular sieve morphology on methanol to olefins performance WU Lei, LIU Ziyu, XIA Lin, QIU Minghuang, LIU Xu, ZHU Haojia, SUN Yuhan 2013, 34 (7):  1348-1356.  DOI: 10.1016/S1872-2067(12)60575-0 Abstract ( 564 )   [Full Text(HTML)] () PDF (737KB) ( 920 )   SAPO-34 molecular sieve samples with sheet-like and cubic morphology were synthesized under microwave and hydrothermal conditions, respectively. The sheet-like SAPO-34 was 130 nm thick with a Brunauer-Emmett-Teller (BET) surface area of 593 m2/g, while the cubic sample was 1.5-2.5 μm in size with a BET surface area of 708 m2/g. Both samples exhibited a similar density for strong acid sites, while the cubic SAPO-34 possessed less weak acid sites. A methanol to olefins catalytic test carried out at 450 ℃ and 1.0 h-1 showed that the sheet-like SAPO-34 exhibited a long stability life of 380 min and gave a high ethylene selectivity of 51.77% and a high total selectivity for ethylene, propylene, and butylene of 90.20%. However, the stability life for the cubic SAPO-34 was only 212 min, and the ethylene selectivity and total selectivity for ethylene, propylene, and butylene decreased to 49.84% and 86.81%, respectively. It is thought that the longer stability life and higher olefin selectivity for sheet-like SAPO-34 occur because of the shorter diffusion path that hinders the further conversion of produced olefins and coke formation.

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Catalytic decomposition of N2O on cobalt substituted barium hexaferrites Barkat UL-AIN, Safeer AHMED, HUANG Yanqiang 2013, 34 (7):  1357-1362.  DOI: 10.1016/S1872-2067(12)60587-7 Abstract ( 497 )   [Full Text(HTML)] () PDF (1429KB) ( 756 )   Catalytic decomposition of N2O was studied over Co substituted Mg-Y type hexaferrites (Ba2Mg2-xCoxFe12O22, x = 0.4-2.0). The materials were synthesized by a sol-gel method using citric acid as the chelator followed by calcination at 1223 K for 5 h. X-ray diffraction, thermogravimetric analysis/derivative thermogravimetric, scanning electron microscopy, and N2 adsorption techniques were used to confirm the formation of hexaferrite. The Ba2Mg2-xCoxFe12O22 catalysts displayed good activity for decomposition of high concentration N2O (30 vol%), and complete substitution of Mg for Co lowered the complete conversion temperature from 1123 K to 973 K. Increasing calcination temperature suppressed the catalytic activity by deteriorating surface area. Moreover, coupling microwave discharge significantly boosted the catalytic activity. Co substituted Mg-Y type hexaferrites are potentially active and thermally stable to be used as catalyst for high concentration N2O decomposition.

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Synthesis, characterization, and catalytic performance of bifunctional titanium silicalite-1 LI Hao, LEI Qian, ZHANG Xiaoming, SUO Jishuan 2013, 34 (7):  1363-1372.  DOI: 10.1016/S1872-2067(12)60589-0 Abstract ( 462 )   [Full Text(HTML)] () PDF (515KB) ( 797 )   A series of bifunctional Ti-molecular sieves (M-TS-1, M = Al, B, or Fe) containing different trivalent ions (Al3+, B3+, or Fe3+), with MFI topology, were synthesized using tetrapropylammonium bromide, silica sol, and n-butylamine as a template, base, and Si source, respectively. The simultaneous presence of Ti and trivalent ions in lattice positions provided catalysts with activity in both oxidation and acid-catalyzed reactions. The samples were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, NH3 temperature-programmed desorption, inductively coupled plasma atomic emission spectroscopy, and N2 adsorption-desorption isotherms. The results showed that the numbers and strength of acid sites of TS-1 were enhanced by the incorporation of trivalent ions. Using selective oxidation of ethylene as the probe reaction, the catalytic properties of M-TS-1 were investigated. The results showed that Al-TS-1 and B-TS-1 had better catalytic properties; conversion and utilization of H2O2 reached 95% and 90%, respectively, and the yield of ethylene glycol plus its monomethyl ether was greater than 10%.

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Ru(II) pyridyl-based NNN complex catalysts for (asymmetric) transfer hydrogenation of ketones at room temperature DU Wangming, WANG Qingfu, YU Zhengkun 2013, 34 (7):  1373-1377.  DOI: 10.1016/S1872-2067(12)60583-X Abstract ( 574 )   [Full Text(HTML)] () PDF (541KB) ( 604 )   Ru(II) complexes bearing pyridyl-based benzimidazolyl-imidazolinyl tridentate NNN ligands were synthesized and structurally characterized. Their molecular structure was confirmed by X-ray crystallography. These complexes demonstrated good to excellent catalytic activity in the asymmetric transfer hydrogenation of ketones at room temperature, achieving up to 99% yields and 97% ee values.

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Recyclable Fe3O4@SiO2-Ag magnetic nanospheres for the rapid decolorizing of dye pollutants SUN Lijuan, HE Jiang, AN Songsong, ZHANG Junwei, ZHENG Jinmin, REN Dong 2013, 34 (7):  1378-1385.  DOI: 10.1016/S1872-2067(12)60605-6 Abstract ( 473 )   [Full Text(HTML)] () PDF (1014KB) ( 1186 )   A simple electroless plating method using non-toxic, cost-effective precursors to fabricate Fe3O4@SiO2-Ag nanospheres for catalytic reduction of dye pollutants is developed. Incorporating the individual advantages of Ag and Fe3O4 nanoparticles, the Fe3O4@SiO2-Ag nanospheres exhibit enhanced catalytic reduction efficiency for rhodamine B and eosin Y compared with those of pure Ag or Fe3O4 nanoparticles, and can also be rapidly separated from aqueous solution using a magnet. The catalytic reaction rate is strongly dependent on both reaction temperature and Fe3O4@SiO2-Ag dosage. The presence of surfactants and inorganic salt (Na2SO4) influences the catalytic activity of the Fe3O4@SiO2-Ag nanospheres. Fe3O4@SiO2-Ag nanospheres show great promise for the treatment of industrial dye pollutants.

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The roles of hydroxyapatite and FeOx in a Au/FeOx-hydroxyapatite catalyst for CO oxidation ZHAO Kunfeng, QIAO Botao, ZHANG Yanjie, WANG Junhu 2013, 34 (7):  1386-1394.  DOI: 10.1016/S1872-2067(12)60590-7 Abstract ( 544 )   [Full Text(HTML)] () PDF (746KB) ( 900 )   A FeOx-modified hydroxyapatite (HAP, Ca10(PO4)6(OH)2)-supported gold catalyst is highly active and stable during CO oxidation at low temperature, and it is also sinter-resistant to calcination at temperature up to 600 ℃. This work used catalyst characterization and activity tests to investigate the roles of the HAP support and FeOx promoter in CO oxidation. XPS results suggested that a strong interaction between the HAP support and the Au and FeOx nanoparticles gave the sintering resistance. In situ DRIFT studies revealed that the addition of FeOx changed the nature of the reaction mechanism and intermediates to promote catalytic activity. TEM and Mössbauer examination of the spent catalysts in combination with the in situ DRIFT results suggested that the better stability of Au/FeOx-HAP originated from its better prevention of carbonate accumulation.

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Effect of pore structure of mesoporous carbon on its supported Ru catalysts for ammonia synthesis ZHOU Yaping, LAN Guojun, ZHOU Bin, JIANG Wei, HAN Wenfeng, LIU Huazhang, LI Ying 2013, 34 (7):  1395-1401.  DOI: 10.1016/S1872-2067(12)60596-8 Abstract ( 720 )   [Full Text(HTML)] () PDF (2330KB) ( 1114 )   Mesoporous carbon (MC) was prepared by a hard-template method and used as support for the preparation of a Ru-based ammonia synthesis catalyst, Ba-Ru-K/MC. N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy were used to characterize the mesoporous carbon and its supported Ru catalysts. The effects of pore structure of the Ba-Ru-K/MC catalyst on its performance for ammonia synthesis were studied. The results show that the surface area of the mesoporous carbon material varies with the SiO2/C mass ratio and reaches the largest at 1.0 of SiO2/C. The catalytic activity of Ba-Ru-K/MC for ammonia synthesis increases with increased mesoporous surface area of the mesoporous carbon. The reaction rate of ammonia synthesis is 139 mmol/(gcat·h) at 425 ℃, 10 MPa, and a gas hourly space velocity of 10000 h-1.

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Dehydration of xylose to furfural using a Lewis or Brönsted acid catalyst and N2 stripping Iker AGIRREZABAL-TELLERIA, Cristina GARCÍA-SANCHO, Pedro MAIRELES-TORRES, Pedro Luis ARIAS 2013, 34 (7):  1402-1406.  DOI: 10.1016/S1872-2067(12)60599-3 Abstract ( 468 )   [Full Text(HTML)] () PDF (314KB) ( 1257 )   The activity of Lewis (Nb2O5) and Brönsted (Amberlyst 70) acid catalysts for the cyclodehydration of xylose to furfural was studied. The nature of the acidity resulted in significant changes in the reaction mechanism. Lewis acid sites promote the formation of xylulose, while Brönsted acid sites are required to further dehydrate the sugar to furfural. Amberlyst 70 in water/toluene at 175 ℃ showed lower activity but gave a higher furfural yield. Using N2 as the stripping agent considerably improved the furfural yield and product purity in the stripped stream. Catalyst stability was also studied.

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Fuel reforming over Ni-based catalysts coupled with selective catalytic reduction of NOx ZHAO Jiaojiao, YU Yunbo, HAN Xue, HE Hong 2013, 34 (7):  1407-1417.  DOI: 10.1016/S1872-2067(12)60598-1 Abstract ( 577 )   [Full Text(HTML)] () PDF (652KB) ( 667 )   La2O2CO3, CeO2, ZrO2, and Al2O3 supported Ni catalysts were prepared by an impregnation method and employed for reforming of n-dodecane to simultaneously produce low molecular weight hydrocarbons (HCs) and H2. These reforming products served as reductants and promoters for the selective catalytic reduction (SCR) of NOx over Ag/Al2O3. N2 adsorption-desorption, X-Ray powder diffraction, H2 temperature programmed reduction, and thermogravimetric analysis were performed for Ni-based catalysts. It was shown that an increase in the redox performance of Ni-based catalysts enhanced the H2 production from fuel reforming but decreased the amount of HCs available for further SCR reaction. The temperature window for NOx removal using the coupled system shifted to lower temperatures at the expense of the NOx conversion. An optimal ratio of H2/HCs was achieved using a Ni/ZrO2+Ag/Al2O3 dual catalyst system, which exhibited high activity for NOx conversion at typical diesel exhaust temperatures. Studies on the durability and performance of this Ni/ZrO2+Ag/Al2O3 coupled system were also performed, and the results showed that the lifetime of the reforming catalyst may limit the system and requires further improvement.

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Preparation and characterization of Pd/N codoped TiO2 photocatalysts with high visible light photocatalytic activity YU Xinluan, WANG Yan, MENG Xiangjiang, YANG Jianjun 2013, 34 (7):  1418-1428.  DOI: 10.1016/S1872-2067(12)60597-X Abstract ( 532 )   [Full Text(HTML)] () PDF (1142KB) ( 691 )   Pd/N codoped TiO2 photocatalysts were prepared by annealing nanotubular titanic acid, uniformly dispersed urea, and palladium chloride in air or nitrogen atmosphere. The resultant photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and electron spin resonance spectroscopy. The results showed that the calcination atmosphere played an important role in the morphology, crystal structure, spectral absorption, oxygen vacancy concentration, and visible light photocatalytic performance of the catalysts. The photocatalytic performance of samples calcined in an air atmosphere was better than those calcined in a nitrogen atmosphere. The visible light photocatalytic activity of the samples was investigated by monitoring the photocatalytic oxidation of propylene. It was found that the samples prepared at 400 ℃ in air possessed the highest photocatalytic activity under visible light irradiation (λ ≥ 420 nm). The mechanism of the visible light response of the Pd/N codoped TiO2 photocatalysts was discussed in depth, and the origin of the visible light photocatalytic activity was attributed to both the elemental Pt/N dopants and the existence of oxygen vacancies.

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Hierarchical mesoporous ZSM-5 zeolite with increased external surface acid sites and high catalytic performance in o-xylene isomerization ZHOU Jian, LIU Zhicheng, LI Liyuan, WANG Yangdong, GAO Huanxin, YANG Weimin, XIE Zaiku, TANG Yi 2013, 34 (7):  1429-1433.  DOI: 10.1016/S1872-2067(12)60602-0 Abstract ( 661 )   [Full Text(HTML)] () PDF (544KB) ( 954 )   Surface acid sites of hierarchical mesoporous ZSM-5 zeolite synthesized by steam-assisted crystallization were characterized by NH3 temperature-programmed desorption and in-situ infrared spectroscopy. Compared with the conventional ZSM-5 zeolite, the hierarchical ZSM-5 zeolite had a lower concentration of surface acid sites. However, the hierarchical structure had more Lewis acid sites and, more importantly, much more external active sites as confirmed by 2,6-di-tert-butylpyridine infrared spectroscopy. Such hierarchical structure exposed more acid sites on the external surface, which subsequently lead to higher catalytic activity in reactions involving bulky molecules, such as o-xylene isomerization.

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An atomistic thermodynamics study of the structural evolution of the Pt3Ni(111) surface in an oxygen environment SUN Dapeng, ZHAO Yonghui, SU Haiyan, LI Weixue 2013, 34 (7):  1434-1442.  DOI: 10.1016/S1872-2067(12)60604-4 Abstract ( 524 )   [Full Text(HTML)] () PDF (638KB) ( 689 )   The structural evolution of the Pt3Ni(111) surface under oxidizing conditions was studied by ab initio atomistic thermodynamics. The thermodynamic phase diagram from Ni-rich to Pt-rich conditions with oxygen coverages up to one monolayer was constructed from their 560 possible surface structures. With an increase in the oxygen chemical potential, there were only two types of thermodynamically stable structures, which were a clean Pt-skin surface and a Ni-skin surface with chemisorbed oxygen, regardless of the underlying Pt-rich or Ni-rich conditions. Bimetallic surfaces with chemisorbed oxygen were only metastable. The detail analysis revealed that the structural evolution is determined by the factors of segregation cost, difference between oxygen-metal (Pt and Ni) bonding strength, and oxygen chemical potential.

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A nanocrystalline MgO support for Ni catalysts for steam reforming of CH4 Mahmood ANDACHE, Mehran REZAEI, Mansour KAZEMI MOGHADAM 2013, 34 (7):  1443-1448.  DOI: 10.1016/S1872-2067(12)60606-8 Abstract ( 454 )   [Full Text(HTML)] () PDF (811KB) ( 971 )   Nanocrystalline MgO with a relatively high surface area and mesoporous structure was synthesized by a surfactant assisted precipitation method for use as the support of nickel catalysts for steam reforming of methane. The samples were characterized by X-ray diffraction, N2 adsorption, temperature-programmed reduction, temperature-programmed oxidation, scanning electron microscopy, and transmission electron microscopy. The catalysts showed high catalytic activity and good stability in the steam reforming of methane. Increasing the nickel loading up to 10 wt% gave increased activity. Catalysts with higher nickel loadings showed more deposited carbon after reaction. The excellent anti-coking performance of the catalysts was attributed to the formation of a nickel-magnesia solid solution, basicity of the support surface, and nickel-support interaction.

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Preparation and characterization of Ni-Ti-O mixed oxide for selective catalytic reduction of NO under lean-burn conditions YUAN Deling, LI Xinyong, ZHAO Qidong 2013, 34 (7):  1449-1455.  DOI: 10.1016/S1872-2067(12)60614-7 Abstract ( 438 )   [Full Text(HTML)] () PDF (590KB) ( 559 )   A novel Ni-Ti-O mixed-oxide catalyst was prepared by a homogeneous coprecipitation method and tested in the selective catalytic reduction of NO by propene (C3H6-SCR) in the presence of excess O2. Catalysts with different molar ratios of Ni-Ti were characterized using X-ray diffraction, N2 adsorption-desorption, pyridine adsorption, temperature-programmed desorption, and in-situ Fourier-transform infrared spectroscopy. The Ni1Ti1 catalyst showed good activity in C3H6-SCR at 430 ℃ and the NOx conversion achieved 68%. This catalyst displayed an anatase structure and had a high surface area (149 m2/g), which is helpful to enhance the catalyst activity. Lewis acid sites were beneficial for adsorbing nitrate, which was the main intermediate produced during the SCR of NO by C3H6.

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Synthesis, structural analysis and evaluation of the catalytic activity of a non-symmetric N-(salicylidene)diethylenetriamine complex of copper(II) Hassan HOSSEINI-MONFARED, Sohaila ALAVI, Milosz SICZEK 2013, 34 (7):  1456-1461.  DOI: 10.1016/S1872-2067(12)60616-0 Abstract ( 443 )   [Full Text(HTML)] () PDF (299KB) ( 768 )   A new copper(II) complex of a non-symmetric Schiff base, [CuII(saldien)(H2O)]+ (1), has been synthesized and characterized by elemental analysis and several other spectroscopic methods (Hsaldien = N-(salicylidene)diethylenetriamine). The crystal structure of 1 has also been determined by X-ray crystallography. The geometry of the complex cation in 1 was found to be distorted square pyramidal with the mononegative Schiff base coordinating to the copper in a tetradentate mode via the O,N,N', and N''-donor atoms. The remaining coordination site was occupied by the O atom of a H2O molecule in the axial position. The catalytic potential of 1 was tested in the oxidation reactions of cyclooctene and cyclohexene with aqueous 30% H2O2/NaHCO3 in acetonitrile. These reactions proceeded smoothly to give the corresponding epoxides with selectivity levels greater than 99%. This catalytic system also showed high levels of activity and selectivity towards the oxidation of cyclohexane (i.e., cyclohexanol 37% and cyclohexanone 54%) in comparison with most of the other Cu-based systems reported in the literature.

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Catalytic steam reforming of rice straw biomass to hydrogen-rich syngas over Ni-based catalysts LI Qingyuan, JI Shengfu, HU Jinyong, JIANG Sai 2013, 34 (7):  1462-1468.  DOI: 10.1016/S1872-2067(12)60618-4 Abstract ( 511 )   [Full Text(HTML)] () PDF (643KB) ( 856 )   Ni-based catalysts with SiO2, γ-Al2O3, CaO, and TiO2 as supports and MgO-7.5% Ni/γ-Al2O3 catalysts with different contents of MgO were prepared. The structure of the catalysts was characterized by powder X-ray diffraction and N2 adsorption-desorption measurements. The performance of the catalysts in the steam reforming of rice straw biomass to syngas was evaluated. The effects of reaction conditions on the activity of the catalysts were also investigated. Ni-based catalysts supported on γ-Al2O3 had higher catalytic activity than the catalysts supported on TiO2, CaO, and SiO2. The yield of H2 reached 1071.3 ml H2/g biomass and the ratio of H2 to CO was 1.4:1 over a 7.5% Ni/γ-Al2O3 catalyst. Addition of MgO to the 7.5% Ni/γ-Al2O3 catalyst improved its catalytic activity. The yield of H2 reached 1194.6 ml H2/g biomass and the ratio of H2 to CO was 3.9:1 over the 1.0% MgO-7.5% Ni/γ-Al2O3 catalyst. MgO not only improves the steam reforming reaction of Ni-based catalysts, but can also promote the water-gas shift reaction. This method shows promise for production of H2-rich syngas from biomass.