Modeling and simulation of H2S effect in high-temperature water–gas shift reaction using coal-derived syngas

• A model for predicting H2S effect on water–gas shift reaction (WGSR) was presented.
• CO conversion decreases with increased H2S concentration.
• H2S coverage rate on catalyst surface increases with decreased reaction temperature.
• H2S effect can be ignored for temperature in the range at which reversed WGSR occurs.

In this study, a model including hydrogen sulfide (H2S) effect on high-temperature water–gas shift reaction (WGSR) performance was built using coal-derived syngas as feedstock. Based on this model, it was found that the H2S coverage rate increases with the decrease in reaction temperature, leading to more significant carbon monoxide (CO) conversion reduction at low reaction temperature. It was also found that the H2S effect can be ignored when the reaction temperature is in the range at which reverse WGSR occurs. In such a temperature range, CO conversion for both with and without the H2S effect approaches equilibrium result. Through parametric studies using this model, it was found that CO conversion depends significantly on the residence time which can be adjusted by varying the flow rate, steam to carbon molar ratio, inlet pressure of syngas and reactor size. For syngas with fixed CO/H2 molar ratio, CO conversion was found to decrease with the increase in carbon dioxide (CO2) content.