Study on the Synergistic Performance of Fe₂O₃/SiO₂Oxygen Carriers and Co-ZSM-5 Catalysts in the Chemical Looping Oxidative Dehydrogenation of Ethane

As an important chemical raw material, the traditional preparation method of ethylene has the problems of high energy consumption and low selectivity. The chemical looping oxidative dehydrogenation process is promising to solve the problem. However, the oxygen carrier used in this process has the problems of low ethane cracking efficiency and selectivity due to excessive oxidation. Combining this process with catalytic dehydrogenation is a new approach. This study synthesized the Fe₂O₃/SiO₂-0.6 oxygen carrier (A) and prepared Co-ZSM-5 (B) catalyst by in situ synthesis and then investigated six combination strategies: alternately packing two, four, and six layers of the oxygen carrier and catalyst; physically mixing the particles at the particle level; physically mixing via co-grinding of fine powders; and the impregnation-calcination method. The results showed that the six-layer alternating (ABABAB) arrangement achieved a 49.5% ethane conversion and 79.3% ethylene selectivity at 700 °C and that the first three cycles maintained a high ethylene yield. The series connection mode with different site proximity and nanoscale site contact significantly improved the ethylene selectivity and yield. The introduction of SiO₂ resulted in a smaller grain size and better dispersion of Fe₂O₃, enhancing the gas diffusion performance. The synergistic effect of the composite catalyst combined the advantages of active oxygen and stable oxygen species, and the optimization of site proximity promoted the rapid release and oxygen transfer of lattice oxygen.