Alkali metal and alkali earth metal-modified La-Fe-based perovskite catalyzed coke combustion

Abstract

Coke catalytic gasification is an efficient method of burning coke. The core of this technology is the preparation of efficient and stable catalysts. A series of different type La-Fe-based perovskite catalysts, including ABO3 (La1-xSrxFeO3, LaK0.04Sr0.25FeO3), R-P (LaK1.7Sr0.2Fe1.7O6) and A2B2O6 (LaKSr0.17Fe1.5O6, LaKSr0.2Fe1.8O6) were prepared by sol-gel method and calcination of metal-organic framework (MOF) precursor method. The activity of perovskite catalytic coke was tested by thermogravimetric analysis and tubular reactor. Among them, LaKSr0.17Fe1.5O6−MOF has the best catalytic activity, with T10, T50, and T90 values of 610.65 °C, 666.86 °C, and 705.84 °C, respectively. LaKSr0.17Fe1.5O6−MOF not only improves coke conversion but also reduces reaction temperature. DFT and experimental results show that doped K and Sr metals promote the formation of many active sites (oxygen vacancies) on the surface of LaKSr0.17Fe1.5O6−MOF, which reduces the adsorption energy of O2 molecules, realizes the oxygen exchange kinetics. The oxygen release regeneration process is achieved between perovskite lattice oxygen and O2 molecules. These processes synergistically promote coke conversion. In addition, it also has strong stable regeneration performance. These results provide a promising strategy for designing and preparing efficient and low-cost catalysts for the practical application of coke removal.