Gas cleaning systems for integrating biomass gasification with Fischer-Tropsch synthesis - A review of impurity removal processes and their sequences

Abstract

Well-established examples of biofuel utilization, such as ethanol and biodiesel, prove that it is possible to establish sustainable ways to progressively reduce the market dependence on fossil fuels, maintain the use of internal combustion engines (ICEs), and mitigate some negative aspects of their utilization. Biomass-to-liquid route (BtL), especially the Fischer-Tropsch (FT) process, represents a pathway for achieving the conversion of biomass into liquid biofuels (i.e., gasoline, diesel, and kerosene). Synthetic fuels obtained from municipal solid waste (MSW) via the FT process have already been studied as a partial substitution for jet fuels, encouraged by tax credits and feedstock availability. The use of biofuels by the aviation market represents an increasing trend, with future projections pointing to a significant insertion of those renewable fuels in commercial products. However, the net cost of the BtL route is still prohibitive for commercial applications due to many technical challenges, for example, the gas cleaning and conditioning process to meet FT process gas quality requirements. The desired gas quality can be achieved by knowing all the key parameters involved, from the feedstock selection, gasification process, and finally, the cleaning system. This work synthesized relevant information on impurities generation and related removal techniques considering the gasification integrated into the Fischer-Tropsch process (G-FT). The review process provides complementary information about the influence of feedstock selection, gasification parameters, measuring techniques, and related issues. Finally, a flexible gas cleaning sequence is proposed by comparing the existing gas cleaning techniques and pathways, observing Fischer-Tropsch synthesis (FTS) gas quality requirements.