Higher Alcohol Synthesis from Bio-Syngas over Na-Promoted CuCoMn Catalyst

Abstract

Na-promoted CuCoMn catalysts were successfully applied to the highly efficient production of higher alcohols from bio-syngas, which was derived from biomass gasification. The influence of Na content and synthesis conditions (temperature, pressure, and gas hourly space velocity (GHSV)) on higher alcohol synthesis was investigated. The CuCoMnNa0.1 catalyst gave the best performance for higher alcohol synthesis. Carbon conversion increased significantly with an increase in temperature at lower than 300 °C but alcohol selectivity showed an opposite trend. A higher pressure was found to be beneficial for higher alcohol synthesis. Increasing the GHSV reduced carbon conversion but increased the yield of higher alcohols. The maximum higher alcohol yield that was derived from bio-syngas was 304.6 g·kg-1·h-1 with the C2+ alcohols (C2-C6 higher alcohols) of 64.4% (w, mass fraction) under the conditions used. The distributions of the alcohols and the hydrocarbons were consistent with Anderson-Schulz-Flory (ASF) plots. Adding Na to the CuCoMn catalysts led to an increase in the selectivity toward the higher alcohols and promoted the dispersion of the active elements, copper and cobalt. X-ray photoelectron spectroscopy (XPS) results suggested that Cu was present as a mixture of Cu+ and Cu0 on the catalyst′s surface after use and Co was present as a mixture of Co2+/Co3+ and Co0. With an increase in sodium addition the Cu0/Cu+ ratio and the Co0 intensity both decreased.