Insights on alkylidene formation on Mo2C: A potential overlap between direct deoxygenation and olefin metathesis

Abstract

There is evidence that there is a potential overlap between olefin metathesis and deoxygenation chemistries on molybdenum carbide catalysts. Ketones and aldehydes are known to undergo selective deoxygenation on Mo2C to form surface alkylidenes, and metal alkylidenes are initiator and propagator sites in olefin metathesis reactions. Moreover, a recent report correlated increased olefin metathesis activity with molybdenum carbide or oxycarbide formation on pre-treatment of a supported molybdenum oxide catalyst in methane. Taken together, these three strands prompt a DFT study of the elementary carbonyl bond scission step of selected aldehydes and ketones to form surface alkylidenes on Mo2C. This theoretical study is extended to an analysis of previously reported experimental reflectance infrared data for the interaction of cyclopentanone and acetaldehyde with a polycrystalline bulk hexagonal Mo2C sample.