Ce-Promoted Rh/TiO 2 Heterogeneous Catalysts Towards Ethanol Production from Syngas
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Ce-Promoted Rh/TiO2 Heterogeneous Catalysts Towards Ethanol Production from Syngas Changming Li • Junmin Liu • Wa Gao Yufei Zhao • Min Wei
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Received: 4 July 2013 / Accepted: 30 August 2013 / Published online: 25 September 2013 Ó Springer Science+Business Media New York 2013
Abstract Direct synthesis of ethanol from syngas derived from coal, natural gas, or biomass is one of the most promising routes for renewable energy production. In this work, Ce-promoted highly-dispersed Rh catalyst on TiO2 support was prepared by the deposition–precipitation method, which exhibits largely enhanced catalytic activity and selectivity for ethanol production from syngas. XRD and TEM reveal a high dispersion of Rh nanoparticles (*1 nm) on the surface of TiO2 support by the introduction of CeO2. It was found that the relative content of Rh and CeO2 imposes significant influence on the catalytic behavior, and the sample of 1 wt% Rh–1 wt% CeO2/TiO2 exhibits the highest CO conversion (32 %) and the largest ethanol selectivity (33 %) under the conditions of 573 K, 3 MPa, H2:CO = 2:1. H2-TPR and XPS results confirm a gradually enhanced electron interaction between Rh and CeO2 with the increase of Ce content; CO-TPD further reveals that the Rh–CeO2 interaction generates a new adsorption site for CO, accounting for the improved selectivity towards ethanol. Therefore, this work provides a facile and effective method for the preparation of Rh– CeO2/TiO2 catalysts with high catalytic behavior, which can be potentially used in syngas conversion to ethanol. Keywords Syngas conversion Ethanol production Rh–CeO2/TiO2 Catalysts
C. Li J. Liu W. Gao Y. Zhao M. Wei (&) State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, People’s Republic of China e-mail: [email protected]; [email protected]
1 Introduction The limited resources of fossil fuels and environmental concerns have stimulated a broad intensive search for alternative energy sources [1, 2]. Ethanol, as a renewable and clean fuel, has attracted increasing attention [3, 4]. The catalytic ethanol production from syngas, which can be conveniently manufactured from natural gas, coal and biomass, [5] becomes one of the most prospective technologies in the new energy fields. Despite the immense amount of research concentrated on this catalytic conversion process, no commercial process exists due to the challenging chemical and technological barriers [6]. The key is to develop efficient catalysts towards ethanol production for practical industrial applications. Rh-based catalysts supported on SiO2 have been known to be the most efficient ones in the synthesis of C2 oxygenates from CO hydrogenation due to their unique CO adsorption behavior [7–14]. Their catalytic activity/selectivity can be further improved by introducing promoters in Rh catalysts such as Fe [15], Mn [16], La [17] and V [18]. Although much progress has been made, a main obstacle in these Rh-based catalysts is their relatively low efficiency for comme
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