Deactivation study of CuCo catalyst for higher alcohol synthesis via syngas

Abstract

Changes in catalytic performance and catalyst structural evolution during the deactivation of the CuCo/TiO2 model catalyst for higher alcohol synthesis via syngas were investigated. The catalytic activity decreases continuously with time-on-stream, although there is no obvious change in total alcohol selectivity. Meanwhile, the products shift gradually to low carbon number, and the chain growth probabilities of both alcohols and hydrocarbons decrease with reaction time. Using ethane hydrogenolysis as the probe reaction, the catalytic activity also declines with time-on-stream, indicating the decrease in the number of surface metallic cobalt ensembles. To elucidate the structural evolution of the catalyst, the calcined, reduced, and used catalysts were analyzed by various techniques. The bulk crystalline phase of the calcined catalyst is CuCo composite oxide, with small CuO nanoparticles spreading on the catalyst surface. After reduction, the oxides are transformed into CuCo alloy and Cu nanoparticles. For the used sample, severe sintering occurs and CoxC forms on the catalyst surface, both of which reduce the number of surface Co atoms and leads to catalytic deactivation.