Cracking–oxidation of dibutyl phthalate: core–shell catalyst, decarboxylation mechanism, and process cost

Abstract

Phthalates are priority control pollutants with potential endocrine-disrupting and carcinogenic effects. Conventional catalytic cracking–oxidation technologies for treating such pollutants often face challenges including catalyst component leaching, active site deactivation, and unclear reaction mechanisms. In this study, a CeO₂/Si-ZSM-5@Al-MS core–shell structured catalyst was successfully constructed by loading CeO₂ onto an all-silica ZSM-5 core and encapsulating it with an aluminum-doped mesoporous silica shell. This catalyst exhibited excellent performance in the catalytic cracking of dibutyl phthalate (DBP), maintaining stable operation for 200 hours and effectively overcoming the technical bottlenecks of traditional processes. Combined density functional theory calculations and gas chromatography-mass spectrometry analysis systematically elucidated the decarboxylation pathway of phthalic anhydride over the CeO₂/Si-ZSM-5 core, which is the hydrolysis product of DBP from the Al-MS shell. Furthermore, the integration of activated carbon thermal desorption with the cracking–oxidation technology exhibits significantly lower operating costs compared to existing DBP wastewater treatment technologies.