Selective C2+ alcohol synthesis by CO2 hydrogenation via a reaction-coupling strategy

Higher alcohol synthesis (HAS) from non-petroleum carbon resources (a mixture of H-2 and CO2) is an attractive but challenging research target. This reaction still suffers from poor higher alcohol (HA) selectivity due to the complexity in the reaction network and uncontrollability in C-C coupling. Herein, we employed a reaction-coupling strategy to achieve selective conversion of CO2 to HAs over multifunctional catalysts composed of a HAS primary component (KCuFeZn) and CH3OH/CO synthesis promoting component (e.g., CuZnAlZr, ZnZr, ZnCrAl). A linear correlation between HA STY over multifunctional catalysts and CH3OH + CO yield over promoting components confirms the key role of extra CHxO*/CO* species in HAS catalysis. After screening, an optimized multifunctional catalyst composed of 4.7KCuFeZn and CuZnAlZr in close proximity realizes nearly 2 times higher HA selectivity (CO-free, 33.0% versus 17.4%) and HA STY (84.0 mg g(KCFZ)(-1) h(-1)versus 42.1 mg g(KCFZ)(-1) h(-1)) than the sole 4.7KCFZ catalyst at the same space velocity on the basis of 4.7KCFZ. Notably, the close proximity of two components by mortar mixing gives >55% selectivity to high value-added C2+ products (HA and light olefins). It is found that the fast migration of CO*/CHxO* species can improve HAS activity via the synergy of two components at the interfaces. Hopefully, this work would provide a promising avenue to improve HAS activity over a multifunctional catalyst affording multiple types of active sites via a reaction-coupling strategy.