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 La1-xSrxMn1-yCoyO3+delta 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 La0.8Sr0.2Mn0.5Co0.5O3+delta exhibited satisfactory performance and good stability in the cyclic redox tests.

Automated summary

In this study, high reactivity and coking resistance of the La1-xSrxMn1-yCoyO3+delta oxygen carriers were achieved by adjusting the levels of Co and Sr. The introduction of cobalt provided surface active sites to accelerate methane activation, while Sr doping increased oxygen vacancies for improved oxygen migration. The optimal substitution ratios of Co and Sr were found to be in the ranges of 0.4-0.5 and 0.2-0.4, respectively, with La0.8Sr0.2Mn0.5Co0.5O3+delta showing satisfactory performance and stability in redox tests.