Syngas methanation over a metal hydride catalyst: Technology performance, efficiency and economic profitability

Abstract

In the last decade, biomass has been considered one of the main renewable energy sources to replace fossil fuels and consequently, biomass conversion technologies for the production of alternative fuels will play a specific role in the future energy as green biofuels for the transport sector or a power generation at small-scale distributed plants. During the thermal conversion - gasification, biomass is converted into more valuable products - syngases which could be used for biomethane production. Though, some challenges still exist related to the broad applicability of the thermal conversion of biomass to biomethane: costly short-life catalysts and a low conversion efficiency due to the high amount of carbon monoxide/dioxide in syngas.To overcome these challenges, an innovative biomethane production concept based on the plasma-assisted gasification and conversion of synthetic gases to biomethane was developed and tested, including research on the adaptability of two catalysts, magnesium nickel and magnesium nickel hydride, for raw syngas conversion. The performance of catalysts was investigated in a fixed bed type reactor using raw syngas obtained from plasma-assisted gasification.The results indicate the magnesium nickel hydride catalysts' good activity and functionality for converting carbon dioxide and carbon monoxide-containing syngas. A high conversion of 0.997 is reached. Determined that the surplus of hydrogen promotes the conversion of carbon oxides, though the volumetric concentration of methane (the maximum of 86.4 vol%) in product gas is reduced. Considering that the developed technology concept can be integrated into small combined heat and power plants, bio-waste generating plants, or decentralized areas as an additional source of renewable energy or biofuel production, the energy-mass balance and economic analysis for the optimization of 1 MWh bio-CH4 production concept was provided.