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

Abstract

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.

A critical review on direct catalytic hydrogasification of coal into CH4: catalysis process configurations, evaluations, and prospects

“…However, little review has been concentrated on this issue. (Saraceno et al 2023) conducted a review of CHG, and the process layouts, hydrogasifiers, and catalysts were elaborated. Whereas, the catalytic mechanisms of coal hydrogasification with the addition of different catalysts (alkali-metal compounds, transition-metal compounds, and alkaline-earth-metal compounds) remain ambiguous.…”

“…The catalysts mainly participate in these two processes to accelerate the C-H 2 reaction. It is also well recognized that the reactivity of catalytic hydrogasification is determined by many factors, such as the nature of catalysts, including addition amount, dispersion, and component, and the properties of model carbon consist of surface area, ash/sulfur content, and degree of condensation (Tomita et al 1983;Liu et al 2017aLiu et al , 2017bZhang et al 2019;Saraceno et al 2023). Disappointingly, although great progress had been made in catalytic hydrogasification of model carbon, the trail nearly ceased and did not extend to catalytic hydrogasification of coal because of the low economic attractiveness of SNG in the 1980-2000s.…”

Investigation of the Kinetics of Pressure Coal Char Hydrogasification

“…The reactor is sterilized with helium and then filled with hydrogen after the sample has been inserted inside. The mass flow controller maintains the hydrogen flow rate at ±1.5% (9). The analyzer calculates the amount of CH4 in the process gas (8).…”

“…It specifically makes sure that hydrogen solution and an additional reactant are supplied to the process. The mass flow controller maintains the hydrogen flow rate at ±1.5% (9). The analyzer calculates the amount of CH 4 in the process gas (8).…”

“…Saraceno et al [9] conducted a comprehensive review of various coal and biomass gasification methods, with a particular emphasis on hydrogasification. The review focused on examining the impact of different factors, including catalytic gasification, on the intensity of the hydrogasification process.…”