Synthesis of mixed alcohols with enhanced C3+ alcohol production by CO hydrogenation over potassium promoted molybdenum sulfide

Abstract

Alcohol mixtures with high C3+ alcohols content can enhance the performance of alcohol mixtures as a blend component in gasoline. Sulfur-resistant potassium promoted molybdenum sulfide (K-MoS2) catalysts enabled synthesizing mixed alcohols through CO hydrogenation. However, the liquid oxygenate selectivity and yield of K-MoS2 catalysts are usually low, and the alcohols follow the Anderson-Schulz-Flory (ASF) distribution, which means methanol and ethanol present the main liquid oxygenates. To achieve high liquid oxygenate selectivity and yield enhancing C3+ alcohol production, we designed multilayer K-MoS2 catalysts possessing a well-contacted MoS2 and KMoS2 phase, respectively. The reduced rim site exposure and the well-contacted MoS2-KMoS2 dual site induced by the multilayer structure enhance the chain growth through CHx β-addition and CO insertion. Accordingly, the observed higher alcohol formation deviates from the ASF distribution. By tailoring the K/Mo ratio, catalysts with varying composition of MoS2 and KMoS2 phases were obtained for suppressing the formation of hydrocarbons and CO2 effectively. An optimized production of liquid oxygenates with enhanced C3+ alcohol production under appropriate reaction temperature became possible. The optimized catalysts have liquid oxygenate selectivity and yield of 29.1–32.7% and 7.9–10.6%, respectively, yet with good stability. C3+ alcohols take up more than 46% (carbon atom fraction) in the liquid oxygenate. The C3+ alcohol yield reaches 3.6–5.1%.