The influence of the support composition and structure (MxZr1-xO2-d) of bimetallic catalysts on the activity in methanol steam reforming
Metal oxide-stabilized zirconia supports (MxZr1-xO2-δ) with different dopants (M = Y, La, Ce) were prepared by coprecipitation method. Bimetallic CuNi and RuRh catalystssupported on MxZr1-xO2-δ 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 NiCu/YxZr1-xO2-(x/2) (x = 0.1–0.3) samples increases with an increase in yttrium concentration due to the formation of oxygenvacancies. 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 NiCu/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 RuRh alloy differed with significantly higher activity and lower selectivity compared with NiCu 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-δ support.