The effect of water on the reaction path during mixed alcohols synthesis from syngas

Abstract

Water is an inevitable by-product in the process of CO/CO2 hydrogenation to downstream chemicals. However, the role of water for mixed alcohols synthesis has been rarely reported so far. Herein, the effect of water was studied on the reaction path itself using a typical ZnCr catalyst, whose structure remained unchanged even after water treatment. It was found that the intentional introduction of water into the reaction system enhanced the space–time yield (STY) of methanol, whereas that of isobutanol was almost unchanged. In situ DRIFTS technique was employed to simulate the whole reaction process and revealed that water only promoted the formation of methanol’s precursors (formate species), but did not promote the production of isobutanol’s precursors (C2 intermediates that formed by formyl species combining with molecularly adsorbed CO species). These findings may enrich the understanding of the formation mechanism of mixed alcohols synthesis.