Hydrophobic modification for CO photo-hydrogenation to olefins with low CO2 selectivity

Abstract

CO photo-hydrogenation is currently attracting a lot of interest as a low energy input technology for the sustainable production of olefins. Herein, a novel photo-driven Fischer-Tropsch to olefins (FTO) catalyst was synthesized by physical mixing a layered-double-hydroxide-derived cobalt catalyst (LD-Co) with a hydrophobic polydivinylbenzene (PDVB). The obtained LD-Co/PDVB catalyst synergistically harnessed the photothermal and catalytic properties of LD-Co with the hydrophobic properties of PDVB to deliver outstanding photothermal FTO performance. Under ultraviolet-visible irradiation, hydrophobic LD-Co/PDVB delivered a higher CO photo-hydrogenation activity than hydrophilic LD-Co, together with a high olefin selectivity (42.72%−50.49%) and greatly suppressed CO2 selectivity (2.89%−11.50%) compared to LD-Co (12.65%−30.61%) at 180–195 °C. Water vapor adsorption-desorption experiments and water-gas shift (WGS) reaction tests revealed that the hydrophobic modification acted to suppress the WGS reaction, thereby boosting the olefin production and suppressing CO2 selectivity. The findings demonstrated that a simple hydrophobic modification can be used to regulate the activity and selectivity of catalysts for photothermal FTO reactions, opening new vistas towards improved photo-driven olefin production.