Highly efficient CO2 hydrogenation to methanol via in-situ condensation and sorption in a novel multi-stage circulating fast fluidized bed reactor

The theme of this study is to explore the enhancement of carbon conversion to methanol by introducing the concept of circulating fast fluidization coupled with in-situ condensation (IC) and in-situ sorption. According to the best of our knowledge, this is the first time a novel multi-stage circulating fast fluidized bed reactor (CFFBR) is implemented in methanol synthesis. The validity of the reactor and thermodynamic models was verified by industrial and experimental data and good agreement is found. It has been found that the combination of IC and in-situ sorption with the short reactor bed policy achieves remarkable improvement in carbon conversion to MeOH (99.20%). The simulation results indicate that considerable improvement in conversion to MeOH (88.02%) can be achieved by the single bed CFFBR configuration with the in-situ sorption. For the same reactor condition, the IC achieves 59.95% conversion to MeOH. It is apparent that sorption is more pronounced than that of IC. Also, it is found that a large multi-stage configuration with IC can greatly improve the carbon conversion to MeOH (98.24%). It has been observed that excessive sorption inhibits the WGS and increases the accumulation of CO, leads to a considerable drop in carbon conversion to MeOH. Two critical points were identified and used to determine the instantaneous equilibrium of the WGS and the beginning of the total carbon conversion to methanol. The results of this study reveal that fascinating phenomena appear when the in-situ sorption with highly selective water adsorbent of zeolite-4A particles is implemented in the single bed CFFBR.