CO<sub>2</sub> Hydrogenation to Methanol over In<sub>2</sub>O<sub>3</sub>: The Size Effect
Linlin Wu, Rui Zou, Chenyang Shen, Changjun Liu
Abstract
Indium oxide (In 2 O 3 ) and In 2 O 3 -supported catalysts for CO 2 hydrogenation to methanol have attracted increasing interest because of their high methanol selectivity, even at elevated temperatures. However, the stability behavior of In 2 O 3 is still not clear. In this work, the size effect of In 2 O 3 on activity and stability has been investigated. It was found that the smaller In 2 O 3 nanoparticle possesses more surface oxygen vacancies as active sites for CO 2 activation and H 2 dissociation. Higher initial activity is achieved. However, the smaller In 2 O 3 nanoparticle is prone to be over-reduced during the reaction, causing a deactivation of In 2 O 3 . On the contrary, the larger In 2 O 3 nanoparticle has a lower initial activity but effectively prevents the over-reduction. The larger particle size helps the stabilization of surface oxygen vacancies and enhances the stability of In 2 O 3 for the hydrogenation of CO 2 to methanol. The present study of the size effect is important for the improvement in the stability of the In 2 O 3 catalyst by either metal loading (to form the In 2 O 3 -supported catalyst) or the formation of In 2 O 3 –ZrO 2 solid solution.