Torrefaction enhanced biomass chemical-looping gasification coupled with CO2-splitting via half doped LaFe0.5M0.5O3 perovskites

Abstract

In order to explore the oxidation and reduction properties of the LaFe0.5M0.5O3(M = Mn, Co, Ni, Cu) perovskites, torrefied biomass (TB) gasification and CO2 splitting were coupled as a whole chemical looping reaction, while the doped LaFe0.5M0.5O3 were prepared and employed as oxygen carriers(OCs) in the chemical looping. An proper torrefaction temperature was screened first for producing more syngas, then the effect of doped perovskites on the chemical looping reaction were evaluated via thermogravimetric analyzer and fixed-bed reactor in terms of the syngas yield and CO formation rate. The results showed that the doped perovskites exhibited higher activity in the gasification process, which promoted the conversion of TB and improved the yield of H2 and CO. Specifically, the CO yield of LaFe0.5Co0.5O3 and the H2 yield of LaFe0.5Ni0.5O3 was improved by about 4 times and 1.3 times respectively compared with original LaFeO3. Moreover, LaFe0.5Ni0.5O3 exhibited better performance in both TB gasification and the CO2 splitting reaction, and the yield of H2 and CO reached 3.71 mmol·g−1 and 1.80 mmol·g−1, respectively. Furthermore, the composition and surface topography evolution of doped perovskite were analyzed via TEM, SEM and XRD, and the results of XPS, EPR and TGA were combined to reveal the reaction mechanism.