Incorporation of Highly Dispersed Cobalt Nanoparticles into the Ordered Mesoporous Carbon for CO Hydrogenation
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Incorporation of Highly Dispersed Cobalt Nanoparticles into the Ordered Mesoporous Carbon for CO Hydrogenation Yifei Yang • Litao Jia • Bo Hou • Debao Li Jungang Wang • Yuhan Sun
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Received: 19 July 2013 / Accepted: 27 September 2013 Ó Springer Science+Business Media New York 2013
Abstract Highly dispersed cobalt nanoparticles were incorporated into the ordered mesoporous carbon (OMC) via the ultrasonically assisted vacuum-pressure impregnation (UAVI) for CO hydrogenation. The as-synthesized samples were subjected to the characterization of N2 physisorption, HAADF-STEM, XRD, XPS, magnetic measurement, H2 chemisorption and 59Co zero field spinecho NMR. It is found that the cobalt particles are exclusively distributed into the channels of OMC and the rigid frameworks significantly bridle the growth of active species to obtain ultrafine cobalt particles with size less than 4 nm. The highly dispersed cobalt nanoparticles perform superior catalytic performances during the CO hydrogenation as compared to the catalyst prepared by the conventional impregnation. The observed stability of novel catalysts outperforms the conventional one during the 96 h evaluation on stream due to the confinement effect to the
Y. Yang (&) L. Jia (&) B. Hou D. Li J. Wang Y. Sun (&) State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, The Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China e-mail: [email protected] L. Jia e-mail: [email protected] Y. Sun e-mail: [email protected] Y. Yang Graduate University of Chinese Academy of Sciences, Beijing 100049, China Y. Sun Low Carbon Conversion Center, Shanghai Advanced Research Institute, The Chinese Academy of Sciences, Shanghai 201203, China
sintering and conglomeration of active species. On the other hand, a typical structural sensitivity is also observed for the highly dispersed catalysts and the coordinativeunsaturated disordered stacking of cobalt atoms renders higher efficiency to improve CO turnover frequency. Besides, a high selectivity to mixed alcohols is also obtained for the highly dispersed catalysts and the yields of methane and methanol decrease gradually with increasing the particle size. Unfortunately, the highly dispersed particles also display a relatively high selectivity to CO2. Keywords Cobalt-based catalysts CO hydrogenation Heterogeneous catalysis Nanoparticles Ordered mesoporous carbon
1 Introduction Supported metal nanoparticles play a crucial role in a range of heterogeneous catalysis, from the mature petrochemical industries to developing clean energy technologies, because of their high activity and selectivity for a large number of important chemical reactions [1, 2]. Specially, in such systems active species are usually dispersed on a high-surface-area support for maximizing the efficiency of catalytic components, to some extent, whose nanoarchitecture dictates the catalytic performance, regardless of their compositions. Actually, numerous fundamental studies have also shown that the unprecedented activity of metal cata
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