Although the gasification of coal is an efficient means of producing syngas, the carbon content of coal is such that gasification produces significantly higher ratios of carbon oxides to hydrogen than might be obtained for example by the steam reforming of natural gas. The CO:H₂ ratio can be adjusted, and more hydrogen produced, by the subsequent application of the water-gas shift (WGS) reaction. This paper presents a review of technologies associated with the catalytic WGS reaction in a fixed-bed reactor that might be incorporated into a coal gasification-based system for H₂ production with CO₂ capture. The main output from this review is the identification of key project areas requiring further research.
The performance of existing, commercially-available catalysts—designed for use in natural gas reforming processes—with coal-derived syngases is an important aspect of developing technologies for coal-based H₂ production. This paper presents an experimental assessment of the performance of selected commercially-available WGS catalysts [two high-temperature catalysts (HT01 & HT02) and a sour shift catalyst (SS01)] with such syngases. For the three commercial catalysts investigated in this study, CO reaction order is found to be in a range of 0.75–1. The effect of changes in H₂O concentration over HT01 is insignificant, while H₂O reaction orders determined using HT02 and SS01 were found to be significantly positive even at high H₂O:C ratios. The CO conversion rate is significantly reduced by increasing CO₂ concentration, while increasing H₂ concentration also causes a slight reduction in CO conversion rate for the three commercial catalysts investigated.