Rationality and practicability of performing water-gas shift at ultrahigh-temperatures: pioneering exploration for short-flow syngas upgrading

Abstract

Water-gas shift (WGS) reaction is an important process linking gasification syngas upgrading to downstream synthesis of pure H₂ or hydrogen-based fuels such as ammonia, methanol, and sustainable aviation fuel (SAF). The conventional WGS reaction is a long process that includes syngas cleaning and cooling, pressurization, and multistep medium- and low-temperature shift reactions. The latest progress in biomass gasification has led to breakthroughs in the production of low-tar and pressurized syngas, which could facilitate a short process flow for the WGS at high temperatures with minimized heat loss and maximized shift kinetics. However, WGS still faces thermodynamic limitations at high temperatures. Herein, a new ultrahigh-temperature WGS (UT-WGS) strategy is explored using a Cr-free hybrid catalyst that contains both catalytic and adsorptive sites. The results revealed that the optimum reaction temperature and H₂O/CO ratio are 600 °C and 2, respectively, while the maximum CO conversion and H₂ content are 67.73 % and 75.42 %. Our research contributes to direct upgrading of gasification syngas and low-cost production of hydrogen-based fuels, which will appeal to a broad scientific and engineering audience.