(560br) Carbon Dioxide Hydrogenation

Kleiber, S., Graz University of Technology
Siebenhofer, M., Graz University of Technology
Lux, S., Graz University of Technology
Hydrogenation of carbon dioxide may on the one hand contribute to reduction of CO2 emissions, on the other hand we might make use of CO2 to raise the energy density of hydrogen based energy carriers by orders of magnitude. The hydrogenation products methane and methanol provide the physical properties for improved energy density of hydrogen based energy carriers. Both constituents do also easily release hydrogen by steam reforming, making them highly feasible for fuel cell powering. However, hydrogenation of CO2 is not free of charge and does need sophisticated stable catalysts, easy to prepare, easy to recycle, robust and stable for long term usage. A suitable catalyst system can improve the reaction conditions concerning temperature, pressure, CO2 conversion, and product yield. State of the art catalysts in industrial methanol production are Cu/ZnO/Al2O3, for methane synthesis Ni-based catalysts with Al2O3 backbone or SiO2 backbone have established.

Changing the catalyst backbone from Al2O3 to MgO is very promising due to the appreciable CO2 capture capacity of MgO as well as the low technological demand for recycling of spent catalysts. Due to the caustic properties of MgO based catalyst systems a product yield close to equilibrium conversion can even be obtained at moderate operation pressure. Exemplarily Ni doped MgO catalysts offer great performances in methanation of CO2 at ambient pressure. For catalyst optimization the Ni-load of MgO has been varied between 11 wt% and 27 wt%. For methanol synthesis the catalyst performance of Cu/MgO and Cu/ZnO/MgO systems has been investigated and compared.