CO2 hydrogenation

Gas phase catalysis

In the "Gas phase catalysis" research focus area, the Institute of Physical Chemistry is primarily investigating the hydrogenation of carbon dioxide to methane. These investigations are based on the power-to-gas concept (Fig. 1). In this concept, surplus energy from renewable sources is stored using water electrolysis. The resulting hydrogen is converted by carbon dioxide into methane, which is a very suitable energy storage medium for the natural gas network. The aim of the work at the institute is to find a particularly active, selective and at the same time stable catalyst for CO₂ methanation. The focus is on nickel-containing compounds, as these samples exhibit high activity in CO₂ hydrogenation. A hydrotalcite-based mixed oxide of aluminium and magnesium oxide is often used as a carrier material. The advantages of this system are its high specific surface area, a highly dispersed distribution of the active nickel centres and the variation of the basicity of the carrier material. These catalysts are synthesised by co-precipitation (Fig. 2) or impregnation. This is followed by a comprehensive, versatile characterisation of the catalysts. The sample composition is analysed by XRD and XPS, the specific surface area by BET and the reduction behaviour by TG-DSC. The samples are reduced using a reduction apparatus. The resulting samples are analysed in a catalyser test stand with a gas chromatograph to determine their performance (Fig. 3). This performance is assessed on the basis of the conversion of the reactants hydrogen and carbon dioxide and on the basis of the yield or selectivity of the product methane. The investigations are carried out as a function of temperature, pressure and reactant composition. In addition, in-situ methods such as DRIFTS are used to investigate the reaction mechanism of CO₂ methanation.

Topics for theses:

For interested students, topics for student research projects, bachelor's and master's/diploma theses can be arranged individually on an ongoing basis.

Selected publications:

N. Bette, J. Thielemann, M. Schreiner, F. Mertens, ChemCatChem 2016, 8, 2903. https://doi.org/10.1002/cctc.201600469
P. Völs, S. Hilbert, B. Störr, N. Bette, A. Lißner, J. Seidel, F. Mertens, Ind. Eng. Chem. Res. 2021, 60, 5114. https://doi.org/10.1021/acs.iecr.1c00028