Carbon dioxide methanation for intensified reactors

The present work is related to the development of sustainable energy systems based on the Power-to-Gas concept. The main objective is to utilise renewable hydrogen and carbon dioxide to produce methane for storage in the natural gas infrastructure. Multitubular fixed-bed reactors are established at industrial scale for CO2 methanation. Catalytic pellets commonly loaded in this type of reactor involve poor heat transfer and high pressure drop that lead to inefficient processes. Today, reaction engineers focus their research on the branch of process intensification. Highlighted features of intensified reactors are improved heat and mass transfer, product efficiency, and reduced size. VTT Technical Research Centre of Finland is developing a technology in methods by washcoating and nanocoating. The aim of this work was to determine the suitability of these novel catalysts for CO2 methanation, and the optimal operation conditions that favour their performance. Washcoated and nanocoated catalysts were tested in laboratory scale and compared with conventional packed-bed catalysts. The reactors were loaded with nickel-based catalysts and operated at three different temperatures (350, 400, and 5000C) and three different flow rates (0.7, 1.0 and 1.3 ln/min), H2:CO2 = 4, and at atmospheric pressure. The catalyst bulk density of washcoated reactors was significantly lower than in packed-bed reactors. As a result, the washcoated catalysts performed better due to more efficient heat transfer and temperature control. Carbon dioxide conversion equal to 69% and 99% methane selectivity were obtained with the washcoat with highest nickel content at 4100C. The good results obtained with washcoated reactors encourage the development of these reactors into scaled-up configurations. Conversely, nanocoated catalysts exhibited lower performance. Nevertheless, the possibility of developing active catalysts minimizing the content of active phase motivates further research on the nanocoating technology