CO2 sorbents for a sorption-enhanced water–gas-shift process in IGCC plants: A thermodynamic analysis and process simulation study

• Thermodynamic criteria were developed to screen SEWGS sorbents.
• Seven sorbents were identified thermodynamically suitable for SEWGS application.
• Process simulation revealed superior energy efficiency of an IGCC + SEWGS plant.

A sorption-enhanced water–gas-shift reaction process (SEWGS) combines the WGS reaction and CO2 removal into a single process step in an integrated gasification combined cycle (IGCC) power plant. In the SEWGS, a solid sorbent is employed to capture the CO2 generated by the WGS reaction. A key technical issue for the SEWGS is to identify and develop sorbents that can capture CO2 under high pressure and high temperature syngas conditions and minimize or even eliminate the need for WGS catalysts. We present the results from a thermodynamic analysis and process simulation study that aimed to identify sorbents and optimal temperature windows to maximize the thermal efficiency of an IGCC + SEWGS plant. The results from the thermodynamic analysis identified two metal oxides, one silicate, three zirconates, and one titanate sorbents that are suitable for the SEWGS application. The results from the process simulation study revealed that the overall thermal efficiency of a 1187 MWth (thermal input) IGCC + SEWGS plant gasifying an Illinois coal, and using the seven sorbents selected from the thermodynamic analysis, was between 0.5 and 2.4 percentage points greater than that of a reference IGCC + Selexol plant.