LAUSR

Methanation is an exothermic process that utilizes catalysts to convert the carbon dioxide and carbon monoxide in biogas to methane, forming synthetic natural gas. The criteria for determining a suitable catalyst should not only be its effectiveness, but also the environmental impact of extracting and refining the metal. The authors examine the environmental impacts of implementing a select group of methanation catalysts in the field for industrial scale synthetic natural gas production using the analytical hierarchy process (AHP). Catalysts containing a combination of rare earth metals are investigated separately and AHP is used to rank the catalysts based on their environmental impact per kg of CO2 converted. It is determined that catalysts containing common metals, such as nickel, have the lowest environmental impact per conversion rate across a number of metrics and represented the catalysts with the second and third highest conversion rates analyzed. Catalysts containing ruthenium are found to be the most detrimental to the environment, in spite of the favorable conversion rate offered by a ruthenium‐cesium catalyst in methanation reactors.