(650c) Catalytic Methanation of Carbon Dioxide with Ni/MgO Catalyst in Dual-Step Reductive Calcination

The heterogeneously catalyzed gas-phase conversion of carbon dioxide with hydrogen to produce methane has gained major interest in recent years [1]. One of the reasons for this increased interest is the quest for hydrogen storage systems. Renewably produced hydrogen is stored via methanation of the greenhouse gas carbon dioxide. Methane can partially substitute natural gas in an established gas grid. Our research focuses on process integration in this context and addresses potential carbon dioxide sources. Calcination is a widely used preparatory step in mineral carbonate beneficiation. During calcination carbon dioxide is released in high concentration into the off-gas. If calcination is performed in hydrogen atmosphere (= reductive calcination), a highly concentrated (CO₂/H₂) process gas stream suitable for direct gas phase methanation can be prepared. Our research [2,3] revealed that reductive calcination is a low temperature process compared to calcination in oxidizing atmosphere, and carbon dioxide is partially converted into methane and/or carbon monoxide in a single-step process. The yield of methane and carbon monoxide can be partially controlled by reaction temperature and pressure. Selective methanation, however, is not achieved in the calcining step. Therefore, methanation of the process gas from reductive calcination by catalytic methanation at ambient pressure with a Ni/MgO catalyst was investigated [4]. Although methanation of CO₂ according to the Sabatier reaction has been investigated since decades, little information about process performance at ambient pressure is available. At moderate temperature (534 K) and ambient pressure CO₂-conversion close to equilibrium conversion beyond 90% is possible. Adsorption of reactants and products does not affect kinteics. At moderate temperature conversion does draw advantages from interaction of carbon dioxide with MgO. Latter effect was confirmed by direct methanation of MgCO₃ with hydrogen without catalytic support.

1. Bailera, M., Lisbona, P., Romeo, L.M., and Espatolero, S. (2017) Power to Gas projects review: Lab, pilot and demo plants for storing renewable energy and CO2. Renew. Sustain. Energy Rev., 69 (January 2016), 292–312.

2. Baldauf-Sommerbauer, G., Lux, S., Aniser, W., and Siebenhofer, M. (2017) Synthesis of carbon monoxide from hydrogen and magnesite/dolomite. Chemie Ing. Tech., 89 (1–2), 172–179.

3. Baldauf-Sommerbauer, G., Lux, S., Aniser, W., and Siebenhofer, M. (2016) Reductive calcination of mineral magnesite: hydrogenation of carbon dioxide without catalysts. Chem. Eng. Technol., 39 (11), 2035–2041.

4. Baldauf-Sommerbauer, G., Lux, S., and Siebenhofer, M. (2016) Methanation of carbon dioxide with a nickel/magnesium oxide catalyst. in: AIChE Annual Meeting 2016, San Francisco, USA.