Performance and dynamic behavior of sorption-enhanced water-gas shift reaction in a fluidized bed reactor for H2 production and CO2 capture

Abstract

A multi-scale dynamic model for a sorption-enhanced water-gas shift (SE-WGS) fluidized bed reactor was developed and the reactor performance in terms of hydrogen production and carbon dioxide capture was analyzed. K2CO3-promoted hydrotalcite sorbent was used as a reference in the SE-WGS fluidized bed reactor and steam methane reforming gas was used as the feed. The sensitivity analysis of the performance was carried out by varying the temperature, pressure, and sorbent circulation rate. The CO conversion achieved at low pressures in the SE-WGS fluidized bed reactor was much higher than the catalytic equilibrium conversion. However, the advantages of the SE-WGS reactor were lost at pressures of over 7 bar. The desired sorption capacity and rate of the CO2 sorbent were suggested to enhance the performance of the SE-WGS fluidized bed reactor at 30 bar. At a five-time higher sorption capacity, the CO conversion and carbon capture efficiencies could be achieved to 95.0% and 86.4%, respectively. In addition, with a simultaneous increase of 1.5 times in the sorption rate, the CO conversion and carbon capture efficiency could be achieved to 99.3% and 98.2%, respectively. Because the CO2 sorption capacity is mainly determined in the mixing zone, the operating conditions need to be finely controlled for the maximum utilization of the sorbent capacity. The study demonstrates the advantages of the SE-WGS fluidized bed reactor for simultaneous H2 production and CO2 capture. In addition, the optimization of the sorption capacity and rate of the CO2 sorbent can provide guidance for the development of high-performance sorbents for application in SE-WGS fluidized bed reactors.