| 초록 |
Understanding coke formation and deactivation in zeolites is of prime importance for designing solid acid catalysts with enhanced lifetime. The cooperative effects of secondary mesoporosity and defect sites on the amount and location of coke formation and catalytic deactivation of zeolite were investigated. After supporting Ga, aromatization results showed that both generating mesoporosity and annealing defect sites effectively retarded catalyst deactivation via the suppression of internal coke formation. The mesoporosity alone could not efficiently reduce the total amount of coke deposition, but it changed the location of coke. In contrast, the annealing of defect sites reduced the total amount of coke. This phenomenon implies that coke precursors are first generated at the internal defects of zeolite, and then deposited as coke at the either internal or external surfaces of the zeolite depending on the relative kinetics of the coke precursor diffusion and its polymerization. The catalyst with secondary mesoporosity and annealed defect sites exhibited the slowest catalyst deactivation due to the highly suppression of both internal and external coke formation. |
