Non-magnetic insulating catalysts are shown to be able to convert non-equilibrium mixtures of hydrogen by an electric mechanism. The molecular electrons feel the difference of temperature between the nuclei and the thermal bath, through their "Fermi" contact interaction, and consequently transfer the rotational angular momenta to the catalyst. This transfer, realized by the electrostatic interactions between the molecular and surface ionic electron clouds, is measured by non-diagonal exchange integrals. Our simple model of single-electron excitations interprets the experimental conversion rates recently observed on different surfaces (MOF or ASW) with different technics (infrared or ionization spectroscopy) and allows the study of the conversion rates in different contexts: thermal as well as transient, metallic or oxygen-induced, ion-molecule and molecule-molecule electron exchanges.