The role of intermediate Co_xMn_1−xO (<i>x</i> = 0.6–0.85) nanocrystals in the formation of active species for the direct production of lower olefins from syngas

Abstract

Cobalt-manganese (CoMn) oxides obtained through a one-pot synthesis can be controllably reduced to CoxMn1-xO nanocrystals for the direct production of C2-C4 olefins with high selectivity (50.9 mol%) from syngas at high CO conversion (92.4%), higher than predicted by the Anderson-Schulz-Flory distribution. The formed CoxMn1-xO is the key to generating an active Co2C quadrangular nanoprism phase with (101) and (020) exposed facets in-situ during the reaction, which plays a pivotal role in the high lower-olefin yield. No deactivation was observed after 100 hours under harsh high-conversion reaction conditions, and the activity is one order of magnitude higher than that of the traditional cobalt catalyst.