Intensified effect of phosphorus doping to La-Fe-O perovskite-type oxygen carrier in microalgae chemical looping gasification for enhanced syngas production

[Display omitted] •Novel P-doped LaFe1-xPxO3 perovskite-type OCs were successfully prepared.•Microalgae CLG performance was significantly enhanced via P doping strategy.•Syngas production over P-doped perovskites was thermodynamic and kinetic favorable.•Surface oxygen species and oxygen vacancies formation were enhanced by P doping. Chemical looping gasification (CLG) with perovskite-type oxygen carriers has been gaining an increasing interest for efficient and clean utilization of biomass resources. Compared with conventional metal-doping method, the incorporation of non-metallic element in perovskite has advantages in reactivity and cost. Herein, a novel phosphorus doping strategy was applied to enhance the reactivity of LaFeO3 for microalgae CLG. Comprehensive studies including kinetic analysis, thermodynamic investigation and gaseous products evaluation were carried out via TG-FTIR-MS method. TG results showed the enhanced CLG performance over LaFe1-xPxO3 oxygen carriers. Specifically, CLG with LaFe0.99P0.01O3 (LFP1) gained the largest pre-exponential factor of 4.38 × 1033 s−1 and average ΔS value of −8.8 J·mol−1·K−1 through kinetic and thermodynamic analysis using FWO method, indicating the enhancing reactivity of MA-LFP1 system. The FTIR and MS spectra also revealed the best CLG performance of LFP1 with the highest total gas yield and syngas production. Meanwhile, the release kinetics of gaseous products demonstrated the minimum E(H2), E(CH4) and E2(CO) values of 14.86, 11.37 and 201.67 kJ/mol, respectively, owing to the highest proportion of surface-active oxygen species and oxygen vacancies on the LFP1 surface confirmed by characterizations. Results in this study provided helpful guidance for designing efficient perovskite-type oxygen carrier via doping with non-metallic elements toward the full utilization of microalgae.