A Review of Coal and Biomass Hydrogasification: Process Layouts, Hydrogasifiers, and Catalysts

Despite the increasing need for chemicals and energy, the scenario in which fossil feedstocks can be completely replaced by renewables is currently unrealistic. Thus, the combination of biomass and non-renewable matrix-based (i.e., coal) technologies could provide a greener way toward the partial substitution of traditional fuels. The hydrogasification of carbonaceous feedstocks (coal and biomass) for the main production of CH4 offers a promising alternative to this end. However, hydrogasification has received very little attention, and the present review seeks to shed light on the process, reactor, and catalytic advances in the field. Independent of the selected matrices, various efforts have been devoted to the identification of efficient methods for the production of hydrogen feed to the gasifier and energy as well as the reduction in pollutant emissions from the plants. Moreover, the reactor configurations proposed are focused on the intensification of gas-solid contact to reduce by-product formation. The co-hydrogasification of both renewable and non-renewable feedstock is also reviewed, paying attention to the synergistic effect between the two matrices. In addition, due to the slow rates of hydrogasification reaction, the key role of catalysts and feedstock impurities on the reaction kinetics is discussed.

Automated summary

Despite the increasing demand for chemicals and energy, the complete replacement of fossil feedstocks with renewables is currently not feasible. However, the combination of biomass and non-renewable matrix-based technologies could provide a greener alternative for partially substituting traditional fuels. The hydrogasification of carbonaceous feedstocks, such as coal and biomass, offers a promising solution for the production of CH4. This review highlights the advancements in the process, reactor design, and catalysts used in hydrogasification, as well as the efforts to improve hydrogen production, energy efficiency, and reduce pollutant emissions. The co-hydrogasification of renewable and non-renewable feedstocks is also discussed, along with the role of catalysts and impurities in the reaction kinetics.