Production of synthetic natural gas: a study of nickel catalysts obtained by solid-state combustion of nickel complexes with ethylenediamine

Bulk nickel and nickel-alumina catalysts were prepared by solid-state combustion (SSC) from energy-rich complexes that are formed by adding liquid ethylenediamine to solid nickel nitrate at molar ratios of 1 : 2 and 1 : 3. It was noted that the fast gasification of a complex mixed with alumina minimized their interaction; therefore, the main condensed combustion product was nickel oxide, as with the combustion of individual complexes. A study of the obtained nickel-containing catalysts for CO₂ methanation showed that a catalytically active phase was formed at temperatures ranging from 250 to 350 °C, even in a reaction medium in the presence of CO₂. It was found that after activation, the nickel-alumina catalyst more effectively catalyzed the methanation of CO₂ compared to the synthesized bulk catalyst and the industrial NIAP-07-01 catalyst containing ∼2 times more nickel. Indeed, the amount of CO₂ converted into methane on the synthesized nickel-alumina catalyst was 1.5, 3, 8 and 9 times higher than on NIAP-07-01 at 350, 300, 250 and 200 °C, respectively. Furthermore, the catalyst synthesized by the SSC method is capable of methanating CO₂ even at 150 °C. Its activity does not decrease over time, and it steadily converts about 55% of CO₂ into methane at 350 °C for 10 hours.