Hydrogenation of carbon dioxide with Fe/Ni-catalysts
Georg Baldauf-Sommerbauer, Susanne Lux, Darren Kong, Matthäus Siebenhofer, Institute of Chemical Engineering and Environmental Technology, Graz University of Technology, NAWI Graz, Graz, Austria
Conversion of carbon dioxide with hydrogen to value-added products could be a substantial approach for CO2 mitigation. The use of sustainably produced hydrogen would have a dual advantage: Firstly, CO2-mitigation and utilization; secondly, chemical hydrogen storage. In this study the performance of low-loaded (0.3-1.0 %wt.), supported, bi-metallic Iron/Nickel (Fe/Ni) catalysts with a Fe/Ni-ration of 2.6-6.6 was investigated with a tubular reactor setup with online gas analysis. Several potential catalysts were screened, whereas two types of commercial support materials (alumina and silica) were compared.
The metal based catalysts were prepared in an incipient wetness method, followed by drying, calcining and reduction steps. The effect of the reduction step was analyzed by the following experimental procedure.
1. Controlled heating (approx. 2.6 K/min) of the catalyst in N2/H2/CO2 (75/20/5 vol.%) from 298 to 773 K (Screening before reduction)
2. Reduction of the catalyst in hydrogen atmosphere at 773 K for two hours
3. Cooling of the catalyst overnight
4. Controlled heating (approx. 2.6 K/min) of the reduced catalyst in N2/H2/CO2 (75/20/5 vol.%)from 298 to 773 K (Screening after reduction)
The analysis of the product gas confirmed the formation of carbon monoxide and methane. Carbon monoxide formation increases with temperature, whereas methane formation passes an optimum between 350 and 425 °C. The support material plays a major role in conversion.
As a main result an optimal catalyst composition and preparation procedure for high CO2-conversion near thermodynamic equilibrium for the reverse watergas-shift reaction at moderate temperature (350-500 °C) was found. This catalyst is applicable for the conversion of a CO2-rich hydrogen feed into a CO-rich process gas for consecutive Fischer-Tropsch-Synthesis or methanol production.
See more of this Group/Topical: Catalysis and Reaction Engineering Division