The influence of the support composition and structure (M_xZr_(1-x)O_(2-δ)) of bimetallic catalysts on the activity in methanol steam reforming

摘要

Metal oxide-stabilized zirconia supports (MxZr1-xO2-delta) with different dopants (M = Y, La, Ce) were prepared by coprecipitation method. Bimetallic Cu Ni and Ru Rh catalysts supported on MxZr1-xO2-delta were prepared by the sequential wetness impregnation method, for use in hydrogen production by methanol steam reforming. The effect of the nature and quantity of the dopant cation (M = Y, Ce) on the catalytic performance of zirconia supported metal catalysts was investigated. The activity of Ni-Cu/YxZr1-xO2-(x/2) (x = 0.1-0.3) samples increases with an increase in yttrium concentration due to the formation of oxygen vacancies. The dependence of the catalytic activity on the ceria concentration was not monotonous. The sample containing 10% of cerium oxide showed the highest activity. The performance of a Ni-Cu/La0.1Zr0,9O1.95 sample was compared with the performance of a Y and Ce containing samples with the same quantity of dopant cation (10%). The La doped catalyst was more active than the yttria-containing composites, but its selectivity was lower. The catalyst based on Ru-Rh alloy differed with significantly higher activity and lower selectivity compared with Ni-Cu samples. The selectivity of the process was not less than 99.5% for all catalysts even at the high temperatures. At the same time, the improved activity of the catalyst also results in an increase in carbon monoxide formation while the hydrogen selectivity decreases. The optimal characteristics, such as rather high hydrogen yield, good selectivity and stability were shown by the catalyst with Ce0.1Zr0.9O2-delta support. (C) 2017 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.