Sorption Enhanced Steam Methane Reforming For Hydrogen Production——Preparation And CO₂Absorption Kinetic Investigation Of Li₄SiO₄

Sorption Enhanced Steam Methane Reforming(SESMR) process was widely investigated theoretically and experimentally because the combination of reaction and CO2absorption in a single unit operation has lots of advantages for achieving lower reaction temperature, high conversions and yields and high H2purity. It is important to select a propriate CO2absorbent and then to study its kinetic behaviors for the application of SESMR.In this study, Li4SiO4was used as the CO2acceptors in the SESMR system. FactSage and HSC softwares were used for the thermaldynamic calculation of the preparation of Li4SiO4and the theoretical condition was achieved. Based on the theoretical results, all samples prepared at different conditions were characterized by XRD and SEM techniques to analyze the purity and crystal appearance of the samples. The results show that pure Li4SiO4powders can be obtained by calcining Li2CO3and SiO2at750℃for6h with Li/Si molar ratio of4.1.The absorption behaviors were studied by TGA method at different temperature under different CO2atmosphere. The results show that double shell model can perfectly fit the CO2absorption mechanism on Li4SiO4. The whole reaction has two stages:rapid reaction stage and ion diffusion control stage.Based on the preparation of pure Li4SiO4, K element was doped into Li4SiO4to improve the absorption ability of the absorbent. The results show that the rapid reaction stage can be extended and the maximum absorption capacity can be significantly improved. Moreover, the absorption ability can maintain as the concentration of CO2decreases and Li4.12K0.24SiO4has a better sorption enhancement than pure Li4SiO4while steam occurs. The reversibility of the is quite well after10cycles.