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乔明华, Yan Pei a, Pingjun Guo a, Minghua Qiao a, ∗, Hexing Li b, Shiqiang Wei c, Heyong He a, Kangnian Fan a
Journal of Catalysis 248 (2007) 303-310,-0001,():
-1年11月30日
Binary CoB and ternary CoFeB amorphous alloy catalysts with different Fe contents were prepared by the chemical reduction method. In liquid-phase hydrogenation of crotonaldehyde, incorporation of Fe into the CoB catalyst reduced the overall activity while effectively improving the selectivity and yield to crotyl alcohol. On the optimum CoFeB-3 catalyst with a nominal Fe/(Co+Fe) molar ratio of 0.6, the initial selectivity amounted to 71%, and the yield of crotyl alcohol reached 63%. It is found that the selectivity enhancement was due to the lower decrement in the intrinsic formation rate of crotyl alcohol compared with that of butanal, not to the increment in the activation of the C=O bond. Based on the characterizations, including X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, and previous findings, the enhanced selectivity from Fe modification was tentatively attributed to an ensemble size effect.
CoB, Fe modification, Amorphous alloy, Crotonaldehyde, Crotyl alcohol, Hydrogenation, Ensemble size effect
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乔明华, Xueying Chen, † Minghua Qiao, † Songhai Xie, † Kangnian Fan, † Wuzong Zhou, *, ‡ and Heyong He*, †
Published on Web 10/04/2007,-0001,():
-1年11月30日
Zeolite analcime with a core-shell and hollow icositetrahedron architecture was prepared by a one-pot hydrothermal route in the presence of ethylamine and Raney Ni. Detailed investigations on samples at different preparation stages revealed that the growth of the complex single crystalline geometrical structure did not follow the classic crystal growth route, i.e., a crystal with a highly symmetric morphology (such as polyhedra) is normally developed by attachment of atoms or ions to a nucleus. A reversed crystal growth process through oriented aggregation of nanocrystallites and surface recrystallization was observed. The whole process can be described by the following four successive steps. (1) Primary analcime nanoplatelets undergo oriented aggregation to yield discus-shaped particles. (2) These disci further assemble into polycrystalline microspheres. (3) The relatively large platelets grow into nanorods by consuming the smaller ones, and meanwhile, the surface of the microspheres recrystallizes into a thin single crystalline icositetrahedral shell via Ostwald ripening. (4) Recrystallization continues from the surface to the core at the expense of the nanorods, and the thickness of the monocrystalline shell keeps on increasing until all the nanorods are consumed, leading to hollow single crystalline analcime icositetrahedra. The present work adds new useful information for the understanding of the principles of zeolite growth.
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乔明华, Liang-Feng Chen a, Ping-Jun Guo a, Ming-Hua Qiao a, ∗, Shi-Run Yan a, He-Xing Li b, Wei Shen a, Hua-Long Xua, Kang-Nian Fan a
Journal of Catalysis 257 (2008) 172-180,-0001,():
-1年11月30日
Cu/SiO2 catalysts prepared by the ammonia-evaporation (AE) method have been systematically characterized focusing on the effect of the AE temperature during catalyst preparation. It is found that the texture, composition, and structure of the calcined and reduced Cu/SiO2 catalysts were profoundly affected by the AE temperature. Based on characterizations and previous findings, the copper species on calcined Cu/SiO2 samples and reduced Cu/SiO2 catalysts were assigned. In gas-phase hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG), the evolution of the catalytic activity with the Cu0 and Cu+ surface areas suggested that Cu+ also participated in the hydrogenation process. The cooperative effect between Cu0 and Cu+ is proposed to be responsible for the highest hydrogenation activity of the Cu/SiO2 catalyst prepared at the AE temperature of 363K, on which an EG yield of 98% was obtained under the optimized hydrogenation conditions.
Cu/, SiO2, Ammonia-evaporation, Copper phyllosilicate, Dimethyl oxalate, Ethylene glycol, Hydrogenation
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乔明华, Bo Liu, ¤ Minghua Qiao, ¤ Jing-Fa Deng, ¤ Kangnian Fan, ¤ Xiaoxin Zhang, y and Baoning Zongy
Journal of Catalysis 204, 512-515 (2001),-0001,():
-1年11月30日
A novel skeletal Ni catalyst, prepared by alkali leaching of a Ni-Al alloy obtained by the rapid quenching technique, exhibited higher selectivity in hydrogenation of 2-ethylanthraquinone to "active quinones" than that of the Raney Ni catalyst originating from a conventional alloy. It is suggested that the structural defects of the rapidly quenched alloy lead to a high population of the strongly bound hydrogen, which is essential for selective hydrogenation of the carbonyl group.
skeletal Ni, rapid quenching, 2-ethylanthraquinone, hydrogenation, hydrogen peroxide.,
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乔明华, Fuzhong Xie a, Xianwen Chu a, Huarong Hu a, Minghua Qiao a, ∗, Shirun Yana, Yuanlong Zhu a, Heyong He a, Kangnian Fan a, Hexing Li b, Baoning Zong c, Xiaoxin Zhang c
Journal of Catalysis 241 (2006) 211-220,-0001,():
-1年11月30日
Sn may block the active sites for CO adsorption and/or dissociation, thus suppressing the undesired methanation reaction. On the other hand, bifunctional Ni-Sn ensembles may form, in which Sn facilitates H2O dissociation while neighboring Niadsorbs CO, thus promoting the desired water–gas shift reaction, leading to more H2.
Skeletal Ni, Rapid quenching, Sn modification, Aqueous-phase reforming, Ethylene glycol, H2 production
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