Cooperative Co0 /CoII Sites Stabilized by a Perovskite Matrix Enable Selective C-O and C-C bond Hydrogenolysis of Oxygenated Arenes.

Abstract

Strontium-substituted lanthanum cobaltite (La0.8 Sr0.2 CoO3 ) matrix-stabilized Co0 /CoII catalytic sites were prepared, which present tunable C-O and C-C hydrogenolysis activity for the vapor-phase upgrading of oxygenated arenes. CoII sites associated with oxygen vacancies were favored at low temperatures and performed selective C-O hydrogenolysis, in which Sr-substitution facilitated oxygen vacancy formation, leading to approximately 10 times higher reactivity compared to undoped LaCoO3 . Co0 sites were favored at high temperatures and performed extensive C-C bond hydrogenolysis, generating a wide range of alkanes. The lower reaction order with P (1.1±0.1) for C-C hydrogenolysis than for C-O hydrogenolysis (2.0±0.1) led to a high selectivity towards C-C hydrogenolysis at low P . The Co3 O4 surfaces featured a narrower temperature window for obtaining the respective optimal CoII and Co0 pairs compared to analogous perovskite surfaces; whereas, the perovskite matrix stabilizes these pairs for selective C-O and C-C hydrogenolysis. This stabilization effect offers an additional handle to control reactivity in oxide catalysts.