Characterization and Catalytic Properties of the Ni/Al 2 O 3 Catalysts for Aqueous-phase Reforming of Glucose
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Characterization and Catalytic Properties of the Ni/Al2O3 Catalysts for Aqueous-phase Reforming of Glucose Guodong Wen Æ Yunpeng Xu Æ Zhusheng Xu Æ Zhijian Tian
Received: 2 November 2008 / Accepted: 29 November 2008 / Published online: 13 December 2008 Ó Springer Science+Business Media, LLC 2008
Abstract Two Ni/Al2O3 catalysts with high Ni loadings of 36 wt% and 48 wt%, which possess high activities for aqueous-phase reforming of glucose, have been successfully prepared by a novel two-step impregnation method. The catalytic performance was investigated at 533 K and autogenous pressure in a batch reactor and a significant enhancement in hydrogen yield was observed over the catalyst prepared by two-step impregnation as compared to the corresponding catalyst prepared by conventional single impregnation. The catalysts were characterized by XRD, N2 adsorption/desorption, H2 chemisorption, O2 uptake, TPO, H2-TPR and TEM. It was found that two-step impregnation yielded catalysts with higher nickel dispersion as well as smaller nickel particle size compared to single impregnation. Keywords Aqueous-phase reforming Glucose Hydrogen Ni/Al2O3
1 Introduction Biomass was considered as a promising renewable source for hydrogen production compared to the diminishing fossil fuels [1]. Recently, a new process has been reported by Dumesic and co-workers that hydrogen could be efficiently produced from biomass-derived glucose and polyols at mild conditions near 500 K in a single fixed-bed flow reactor aqueous-phase reforming (APR) process [2]. This process is energy saving because part of the water and the oxygenated hydrocarbons with low volatility were not allowed to vaporize. Moreover, APR occurs at low temperatures that the water–gas shift (WGS) reaction is thermodynamically favored, thus lead to low levels of CO. Particular attention had been paid to glucose [3–6], the only compound in this class of reactants that is directly relevant to biomass utilization. APR of glucose occurs according to the following stoichiometric reaction [7]: C6 H12 O6 þ 6H2 O ! 12H2 þ 6CO2
ð1Þ
The following two main reactions would occur during the reaction conditions:
G. Wen Y. Xu Z. Xu Z. Tian (&) Laboratory of Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, People’s Republic of China e-mail: [email protected] G. Wen Graduate University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, People’s Republic of China Z. Tian State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, People’s Republic of China
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C6 H12 O6 ! 6H2 + 6CO
ð2Þ
CO þ H2 O ! CO2 þ H2
ð3Þ
Pt catalysts were identified as promising catalysts for the APR reactions [7]. However, the high cost of Pt makes it advantageous to develop non-precious catalysts. Although non-precious Ni catalyst showed high initial activity that was comparable to Pt catalyst, significant deactivation was observed [8]. Efforts h
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