Oxygen Vacancy-Mediated Hydroxyl Radical Generation over Mn-Doped SrCoO3 Perovskite for Enhanced Steam Gasification of Graphite and Anti-Coking Performance
Abstract
Coke deposits on the inner walls of furnace tubes during the steam cracking process can significantly reduce heat transfer efficiency and ethylene yield. This study designed a series of Co-Mn-based perovskite catalysts with tunable molecular structures, morphologies, and pore structures to achieve in situ and efficient coke removal. This research evaluated the catalytic performance of these catalysts as coke models in the graphite gasification reaction. The optimal synthesis parameters for SrCo1−xMnxO3 (SCM-x) were determined through the sol–gel method. Specifically, the Mn doping content was x = 0.1, citric acid was used as the complexing agent, pH = 3, and calcination was performed at 800 °C, which produced a cubic perovskite structure with a porous, flake-like morphology. Under the optimized reaction conditions (catalyst and graphite particle sizes of 140–150 and 160–180 mesh, 900 °C, 10 wt.% catalyst loading, water flow 0.167 mL·min−1, 120 min), SCM-0.1 achieved a graphite conversion of 64.78%, which around 18 times higher than that without catalyst. The results of XRD, XPS, H2O-TPD, in situ DRIFTS, SEM, and UV analyses revealed that Mn doping increased oxygen vacancy concentration, enhanced oxygen mobility and bound-water adsorption, and promoted the formation of ·OH radicals from water vapor, which effectively accelerates the gasification of graphite. These findings demonstrate the potential of Mn-doped SrCoO3 perovskites as an anti-coking coating material for ethylene cracking furnaces.