Consequence of controlled hydrogen spillover on FeK/CuAl2O4 in CO2 hydrogenation

[Display omitted] •A series of FeK/CuAl2O4 was structurally modified to control catalytic properties.•Intricate interplay of controlled catalytic sites changed hydrogen spillover.•Porosity, oxygen vacancy, and Fe2O3 dispersion on CuAl2O4 surface governed catalysis.•Controlled hydrogen spillover gave a systematic control of product selectivity.•Mutual distance between Cu(0) and Fe2O3 controlled olefin/paraffin ratio. Catalytic hydrogenation of CO2 to hydrocarbons has received considerable attention due to its potential for enhancing environmental sustainability. Although the research on the activity enhancement reached a matured level, achieving systematic selectivity control of CO2-derived hydrocarbons is still a formidable challenge. Herein, we developed a catalytic route for control of hydrocarbon selectivity utilizing hydrogen spillover phenomena using potassium-promoted iron-based catalysts supported on CuAl2O4 spinel oxides (denoted as FeK/CAO) with systematically modified surface properties for controlled activations of CO2 and H2. Different thermal treatments constructed a series of FeK/CAO catalysts having systematically controlled surface compositions of individual catalytic components with their different dispersions and hence mutual distances, different degrees of reducibility, and different concentrations of oxygen vacancy. The controlled surface characteristics changed H2 activation process and hence the hydrogen spillover phenomena during CO2 hydrogenation, resulting in the systematic control of CO2 conversion and hydrocarbon selectivity. Property–performance relationship proposed that the hydrogen spillover can be influenced by the reducibility, the Cu particle sizes, and the distance between hydrogenation catalytic sites and C–C bond formation catalytic sites. This study successfully demonstrates the ability to control the ratio of olefins to paraffins in the hydrocarbon products derived from CO2 hydrogenation.