Double adjustment of Co and Sr in LaMnO3+δ perovskite oxygen carriers for chemical looping steam methane reforming

As a key factor for chemical looping steam methane reforming, the oxygen carrier with high quality is essential. In this work, both high reactivity and coking resistance of the La 1−x Sr x Mn 1−y Co y O 3+δ oxygen carriers are achieved by double adjustment of Co and Sr. The redox tests and characterization results showed that the introduction of cobalt provided surface active sites to accelerate the activation of methane on the surface, and the Sr doping increased the oxygen vacancies which facilitated the migration of oxygen anion in the bulk of the oxygen carrier particles. The doping of Co and Sr can match the supply of oxygen from the bulk and the need of oxygen on the surface of the oxygen carrier particles. The best substitution proportion of Co and Sr could be set in range of 0.4–0.5 and 0.2–0.4, respectively. The La 0.8 Sr 0.2 Mn 0.5 Co 0.5 O 3+δ exhibited satisfactory performance and good stability in the cyclic redox tests. • The Co doping adds active sites for methane activation on the surface of particles. • The Sr doping accelerates the migration of oxygen ions in the bulk of particles. • The supply of oxygen from the bulk matches the need of oxygen on the surface. • The double adjustment of Co and Sr achieves high reactivity and coking resistance.