(204e) Conversion of Syngas into Liquid Hydrocarbons

TDA Research Inc. is developing a continuous, high-pressure homogeneous catalytic process to convert syngas derived from biomass gasification into valuable hydrocarbons including alcohols, acetates, and acids with high selectivity and minimum methane formation. Our process uses metal carbonyl catalyst precursors that form catalytically active anionic carbonyl and metal-carbonyl hydrides. The carbonyl anions catalyze CO-transfer reactions, hydride transfer, and hydrogen reduction, and the carbonyl hydrides transfer both CO and hydrogen. They also exhibit water gas shift activity, which allows ethanol to be made using syngas from biomass gasifiers that have hydrogen to carbon monoxide ratios of one or lower. The rate of ethanol formation exceeds 0.26 g ethanol/g metal catalyst/h, which on a metals basis is higher than the best heterogeneous catalysts reported in the literature (K promoted MoS₂), but with the homogeneous system shows much lower selectivity to methane, a low value product. We also present data for proof of concept for a process that includes methanol and catalyst recycle.

Besides forming methanol and ethanol without the need for added H₂, our catalyst promotes the formation of acids and acetates through the esterification reaction as well as catalyzing numerous reduction and hydroformylation reactions. With water-gas shift, H₂O + CO = H₂ + CO₂, we have demonstrated that no gaseous H₂ need be added to the reactor to form, for example, methanol and ethanol. Recent results have shown the ability to selectivity promote esterification (producing acetates) in addition to carbonylation followed by hydrogenation (producing alcohols). In addition, our homogeneous catalyst’s water-gas shift activity has the potential to minimize residual water in the products leading more energy-efficient product separation.