Effect of Surfactant-Induced Modifications on CuCoMn Catalysts for Higher Alcohol Synthesis

A series of surfactant-modified CuCoMn-based catalysts were prepared for higher alcohol synthesis from biomass-based syngas. Three typical surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and pluronic P123 triblock copolymer (EO20PO70EO20), were employed. Compared to surfactant-free CuCoMn catalyst, CO conversion increased from 17.4% to 29.7% over SDS-modified CuCoMn catalyst, and the selectivity of higher alcohols increased from 22.0% to 41.2% over CTAB-modified catalyst. Besides, the proportions of higher alcohols in total alcohols increased over all surfactant-modified catalysts. The catalysts were characterized by N2 adsorption/desorption, XRD, XPS and IR analysis. The results showed that several more favorable features rendered the CTAB-modified CuCoMn catalyst to be suitable for higher alcohol production, such as the larger pore size, better crystallinity of CuCoMnO4 spinel, moderate surface atomic distribution and lower valence of metallic ions. In addition, it was verified that CTAB addition at the metal precipitation stage was beneficial to higher alcohol synthesis. Surfactant-induced modification provides a promising alternative method for catalyst improvement in synthesis of higher alcohols.