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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, 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, 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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乔明华, Huarong Hu a, Fuzhong Xie a, Yan Pei a, Minghua Qiao a, ∗, Shirun Yana, Heyong He a, Kangnian Fan a, Hexing Li b, Baoning Zong c, Xiaoxin Zhang c
Journal of Catalysis 237 (2006) 143-151,-0001,():
-1年11月30日
Skeletal Ni catalysts (RQ Ni) prepared by alkali leaching of rapidly quenched Ni–Al alloys have been systematically characterized, focusing on the effect of the cooling rate during alloy preparation. It is found that the residual Al content, texture, structure, surface hydrogen species, and active sites of the RQ Ni catalysts can be controlled by the cooling rate of the Ni–Al alloys. In liquid-phase hydrogenation of 2-ethylanthraquinone (eAQ), the RQ Ni catalyst with higher cooling rate favors hydrogenation of the carbonyl group and retards the saturation of the aromatic ring and the formation of the degradation products, thus leading to a higher yield of H2O2. Based on the characterizations, the improved selectivity is ascribed to the dominant population of strongly chemisorbed hydrogen, which is inactive for the hydrogenation of the aromatic ring, along with the electronic interaction between residual metallic Al and Ni, favoring a carbonyl group-bonded configuration of eAQ on the catalyst.
Skeletal Ni, Rapid quenching, Cooling rate, Ni-Alalloy, eAQ, Hydrogenation, H2O2
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【期刊论文】Controlled Synthesis, Characterization, and Crystallization of Ni-P Nanospheres
乔明华, Songhai Xie, † Minghua Qiao, † Wuzong Zhou, *, ‡ Ge Luo, † Heyong He, † Kangnian Fan, † Tiejun Zhao, § and Weikang Yuan§
J. Phys. Chem. B 2005, 109, 24361-24368,-0001,():
-1年11月30日
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