Environmental assessment of carbon dioxide methanation process using mixed metal oxide and zeolite-supported catalysts by life cycle assessment methodology

Carbon dioxide methanation process is a well-known carbon dioxide utilization technology, not only on account of its ability to subside carbon dioxide in the atmosphere but also to produce methane, which is of serious industrial significance. Although this process is promising in terms of tackling greenhouse gases and global warming, it can, on the other hand, release toxic emissions into the atmosphere, rivers and soil during the process. At this point, life cycle environmental assessment emerges as a crucial tool to reveal the overall effects of this technology. This paper presents a life cycle assessment case study for carbon dioxide methanation process to evaluate all aspects of its environmental impacts. Different scenarios for this purpose were considered by changing catalyst types, namely, mixed metal oxide and zeolite-supported metal catalysts. The results showed that the toxic wastes formed and emissions released when using the Ni/Al2O3 catalyst were less compared to the other cases. Not only did the change in material type in the catalyst affect the total emissions, but the catalyst conversion and selectivity had an influence on the life cycle impact of the system as well. Various power generation alternatives considering renewable and non-renewable sources were evaluated, while a combination of natural gas and wind turbines for the initial sources of power generation was found to perform better in terms of environmental impact.