Power-to-Gas: Storing surplus electrical energy. Study of Al2O3 support modification

In this work carbon dioxide methanation was performed in order to produce methane. This process is known as “Power-to-Gas”, which uses the excess of electricity produced from renewable sources to generate hydrogen via water electrolysis. This hydrogen can react with carbon dioxide, obtained from different industrial processes, to generate methane that can be stored, burned or injected into the existing natural gas grid. Thus, different catalysts supported on alumina and cerium/zirconium modified alumina were prepared, using nickel as main active metal and with the addition of small amounts of noble metals, rhodium and ruthenium, in order to increase their catalytic activity. Addition of noble metals increased the dispersion and the reducibility of the nickel species, whilst support modifiers increased the amount of nickel oxide with moderate interaction with the support and non-stoichiometric nickel aluminate species. These species proved to be related with the catalytic activity. For the catalysts tested, promising results were obtained between 640 and 700 K with a methane yield of 70%.