LaCo1−x−yCuxTiyO3/KIT-6 perovskites: synthesis and catalytic behavior in syngas conversion to higher alcohols

Abstract

Highly dispersed LaCo_1−x−yCu_xTi_yO₃/KIT-6 perovskites were synthesized by the citrate method with inert mesoporous KIT-6 addition. The KIT-6 matrix was removed by dissolution in 7% NaOH aqueous solution. The dispersity of perovskites probably varies depending on the largest cation and its content at the B position of the perovskite ABO₃ structure. The Co_S=2³⁺/Co_S=0³⁺ ratio increases with the increase in copper content and in the presence of Ti⁴⁺. It may be explained by the compensation of the distortion of the perovskite structure. The maximum syngas conversion is achieved at n_Co/n_Cu = 7/3. At a higher copper content, the activity of the samples decreases due to the formation of large copper particles (up to 40 nm) in the course of the reduction. The selectivity for alcohols increases with an increase in the proportion of copper and reaches maximum values at a ratio of n_Co/n_Cu close to 1. The distribution of alcohols is the same for all samples, except for LaCo_0.35Cu_0.35Ti_0.3O₃/KIT-6. It can be assumed that the synthesis of alcohols proceeds on bimetallic CoCu particles 3 nm in size and cobalt particles 4–6 nm in size, most likely enriched with copper on the surface.