WassergasShift

WasserGasShift refers to the water-gas shift reaction, a chemical process that converts carbon monoxide and steam into carbon dioxide and hydrogen: CO + H2O → CO2 + H2. The reaction is exothermic and equilibrium favors hydrogen at lower temperatures, but kinetic rates increase with temperature. Consequently, industrial practice typically uses a two-stage configuration: a high-temperature shift stage followed by a low-temperature shift stage.

In industry, WasserGasShift is applied to adjust the hydrogen-to-carbon-monoxide ratio in syngas produced by steam reforming or coal gasification. The resultant hydrogen is used for refinery hydrotreating and hydrocracking, ammonia synthesis, and other chemical processes. The shift equipment is usually integrated after gasification or reforming and after gas cleanup steps that manage sulfur compounds and particulates. To improve overall hydrogen yield, CO2 is often removed or partially swept from the system to shift the equilibrium toward more hydrogen production.

Catalysts and operating conditions: The high-temperature shift typically uses iron oxide–chromium oxide catalysts and operates around 340–420°C. The low-temperature shift uses copper-based catalysts, commonly Cu/ZnO/Al2O3, at approximately 200–250°C. Together, the two stages balance reaction kinetics with thermodynamic drive, maximizing CO conversion while maintaining catalyst life and manageable heat release.

Thermodynamics and design considerations: Because the reaction is exothermic, lowering temperature favors hydrogen production, but too low a temperature slows conversion. Plant designers optimize reactor configuration, pressure, and CO2 removal to achieve desired hydrogen yields. WasserGasShift is a mature, widely deployed unit operation in hydrogen production and industrial gas processing.