Hydrogenation of carbon dioxide as an alternative source of hydrocarbons

Abstract

Nowadays, one of the most promising areas is the chemical utilization of carbon dioxide into chemical products and fuels. Carbon dioxide hydrogenation on catalytic composite membranes for obtai-ning lower hydrocarbons was studied. The developed membrane-catalytic composites are a combination of active catalytic and proton-conducting components deposited on a thermal- and chemical-resistant flexi-ble carrier – heat-resistant Kevlar fabric. As the proton-conducting component was the product of the oxidizing dehydropolycondensation of acetylene. In the assembling of active electrodes of the mem-brane composite standard widely applied industrial catalysts were used: platinum aluminium oxide (Pt/Al₂O₃), aluminium-nickel molybdenum (Ni/Mo/Al), platinum aluminium oxide with the addition of iron (Fe/Pt/Al2O3). Catalytic studies were carried out in a flow-type laboratory reactor, an internal vol-ume divided into two chambers by a composite catalytic membrane. The hydrogenation of carbon diox-ide was carried out in the temperature range of 150–300 ⁰C and a pressure of 1.0 MPa and the molar ra-tio of the initial mixture n(CO₂)/n(H₂) = 1/1.18. The application of the "hydrogen pump’s" principle has allowed in 3-4 times to increase the activity of the membrane composite catalyst. It has been experimen-tally shown that the generation of proton flux through a membrane composite, depending on the selected catalytic component, allows the hydrogenation of carbon dioxide to produce lower hydrocarbons from C₁ to C₅. The active catalytic component, which contains platinum or nickel, leads to the selective hy-drogenation of CO₂ to methane with the possibility of increasing the carbon chain with the formation of alkanes. The iron-containing catalytic component allows the hyd-rogenation of carbon dioxide to me-thane with the possibility of increasing the carbon chain and the formation of alkenes