Paired electrocatalytic alkane dehydrogenation and CO2 reduction in a multicompartment electroreactor using metal-organic framework based proton conducting membranes

January 2021 – December 2024
Alkane dehydrogenation is a central reaction not only in current chemical industry, but also in the revalorization of polyolefin waste feedstock. Dehydrogenation is endothermic and at high temperature (> 500°C) faces selectivity challenges. Here we will dehydrogenate alkanes at moderate temperature (100-200 °C), by driving the reaction with (renewable) electricity in a two-compartment electrochemical reactor. At the anode, we use either a noble metal catalyst that is promoted to enhance its selectivity for mono-dehydrogenation; or a homogeneous pincer Ir catalyst is used, which after alkane dehydrogenation and metal dihydride formation is regenerated at the anode. Ir pincers allow unique, e.g. terminal selectivity. At the cathode, the protons and electrons from the alkane are used to reduce CO2 to formic acid on modified Sn electrodes, which need to operate at the same temperatures as the anodic compartment. Critical is the membrane between anodic and cathodic compartments which must conduct protons even at 100-200°C; mixed matrix membranes with stable polymers (e.g. polybenzimidazole) and metal-organic framework fillers will be designed and applied. All compounds are assembled in a mass-transport optimized electroreactor. Advanced operando techniques (in situ TEM, XRD, DEMS) are applied to characterize the catalyst in the actual reaction conditions, and to measure rates of dehydrogenation, proton transport and CO2 reduction.