Oxygen activity regulation over LaNiO3 perovskites by Ti substitution for chemical looping partial oxidation of methane

The oxygen species in oxygen carriers directly influence the reaction performance in chemical looping processes. This paper describes the relationship between oxygen species and performance in chemical looping partial oxidation of methane (CLPOM) over LaNixTi1-xO3-& delta;(x = 0, 0.25, 0.5, 0.75 and 1) perovskites. Due to the increase of Ti substitution, the predominate reaction during CLPOM gradually changes from complete oxidation to partial oxidation. Quasi in situ XPS characterization suggests that the relative concentration of nucleophilic lattice ox-ygen species for partial oxidation increases with Ti substitution, while the relative concentration of electrophilic adsorbed oxygen species for complete oxidation decreases. The moderate Ti substitution for LaNi0.5Ti0.5O3-& delta; provides the suitable lattice oxygen activity for the methane partial oxidation. Moreover, LaNi0.5Ti0.5O3-& delta; ex-hibits high cyclic stability in redox cycles. This work demonstrates that the regulation of oxygen species dis-tribution and activity is feasible to tailor the reaction performance of oxygen carriers in chemical looping processes.

Automated summary

This paper investigates the influence of oxygen species in oxygen carriers on the reaction performance in chemical looping processes. The study finds that the predominant reaction changes from complete oxidation to partial oxidation with the increase of Ti substitution in LaNixTi1-xO3-& delta;(x = 0, 0.25, 0.5, 0.75 and 1) perovskites during chemical looping partial oxidation of methane. Experimental results indicate that moderate Ti substitution provides suitable lattice oxygen activity for methane partial oxidation, and the LaNi0.5Ti0.5O3-& delta; material exhibits high cyclic stability. This research highlights the feasibility of regulating the distribution and activity of oxygen species to tailor the reaction performance of oxygen carriers in chemical looping processes.