Higher Alcohol Synthesis from CO2 Hydrogenation through a CO2/H2O Co-Transport Membrane Reactor

Abstract

With the rapid development of renewable energy, direct CO2 hydrogenation (CHR) to liquid fuels and value-added chemicals has attracted considerable attention worldwide. Among them, converting the greenhouse gas CO2 into higher alcohols (HAs) is of great significance due to their potential applications as fuel additive and fine chemical intermediates. However, owing to the chemical inertness of CO2 molecules and uncontrollability of C-C coupling, this reaction still suffers from low CO2 conversion, poor HA selectivity and product rate. In this presentation, we show a CO2/H2O co-transport membrane reactor in the presence of multifunctional catalysts to capture CO2 and store H2 in HAs in one step. The results explicitly show that the captured CO2 from flue gas at retentate side can directly react with a sweeping H2 at the permeate side to form liquid chemicals such as HAs with specific catalysts. Due to transportability of H2O, a product of the CHR, from permeate side to retentate side of membrane reactor, the CHR conversion is expected to be shifted towards desirable HAs production. Besides, through gradual addition of CO2 into H2 stream along the membrane length, the tubular CO2/H2O co-transport membrane reactor can create CHR-favorable, high local H2/CO2 ratio for improved CO2 reduction into the reactive C1-species, which is highly desirable to facilitate subsequent C-C coupling and OH insertion to form the wanted HAs.