(281f) Synthesis of Higher Alcohols From Syngas Over a K Promoted Cu-Co-Zn Catalyst In Supercritical Hexanes

Synthesis of higher alcohols, isobutanol in particular, from synthesis gas (syngas) has been attracting interest due to the potential for producing clean and high octane value fuels. Higher alcohols could be either used directly as fuels, as fuels additives for octane enhancement, or as feed stocks in the chemical industry. The abundance of various carbonaceous sources for producing syngas, including coal, natural gas and biomass, makes this process appealing as an alternative to non-renewable petroleum resources. However, due to the highly exothermic nature of the reactions and the underlying kinetic, this procedure suffers from poor productivity and selectivity towards higher alcohols preventing a large scale and economically feasible commercialized process.

For the last two decades, there has been intensive research centered on shifting the synthesis away from methanol and towards higher alcohols, including; i. the use of modified catalysts, ii. utilizing dual-bed reactors, or iii. slurry phase reactors. In this study, a supercritical medium (i.e. hexanes) was employed to investigate the effect of supercritical solvent on the formation of higher alcohols.

In this work, 0.5 wt% K promoted CuCo/ZnO/Al₂O₃ was investigated as a catalyst for the synthesis of higher alcohols from syngas. The catalyst was prepared by coprecipitation methods and tested in a fixed bed reactor using a supercritical hexanes as the reaction medium. The results suggest that the presence of supercritical hexanes improved the heat transfer from the catalyst bed. It has also been observed that the formation of CH₄ was significantly reduced under supercritical hexanes reaction conditions. The results of the catalytic investigations both with and without the supercritical hexane medium demonstrated that supercritical hexane has a significant effect on the selectivity and the productivity towards higher alcohols.