PNNL

Abstract

The catalytic CO hydrogenation is one of the most versatile large-scale chemical syntheses leading to variable chemical feedstock. While traditionally mainly methanol and long-chain hydrocarbons are produced by CO hydrogenation, here we show that the same reaction can be tuned to produce long-chain n-aldehydes, 1-alcohols and olefins, as well as n-paraffins over potassium-promoted CoMn catalysts. The sum selectivity of aldehydes and alcohols is usually >50 wt% whereof up to similar to 97% can be n-aldehydes. While the product slate contains similar to 60% n-aldehydes at p(H2)/p(CO) = 0.5, a 65/35% slate of paraffins/alcohols is obtained at a ratio of 9. A linear Anderson-Schulz-Flory behaviour, independent of the p(H2)/p(CO) ratio, is found for the sum of C4+ products. We advocate a synergistic interaction between a Mn5O8 oxide and a bulk Co2C phase, promoted by the presence of potassium, to be responsible for the unique product spectra in our studies.