Pt/HZSM-5基催化剂双功能协同性对正丁烷催化裂解反应机制的影响

Light alkanes are stable, and they are not fully utilized in chemical industry. Catalytic cracking is an important process for the valorization of light alkanes, and the related study is also of significant importance for the activation and evolution regulation of C‒H bond and C‒C bond. In this work, on the basis of highly stable Pt/HZSM-5 based bifunctional model catalysts constructed by atomic layer deposition, the dehydrogenation component Pt was introduced onto HZSM-5 zeolites with different acidic properties, and their influences on the reaction pathways and formation of targeted light olefins were studied. It was found that the dehydrogenation function of Pt and cracking role of acidic HZSM-5 zeolites work in synergy. Among the catalysts with the introducing of Pt onto HZSM-5 zeolites with different SiO₂/Al₂O₃ ratios, the dehydrogenation effect brought by metal introduction onto zeolite with high SiO₂/Al₂O₃ ratio is stronger than those introduced onto the ones with low SiO₂/Al₂O₃ ratios. Meanwhile, the introducing of dehydrogenation component onto acidic supports with different cracking abilities would also vary the formation pathways of light olefins. Specifically, with introducing Pt, the pathway of butene formation is enhanced on zeolite with high SiO₂/Al₂O₃ ratio, while the pathways of ethene and propene formation are strengthened on zeolites with low ones. With further decreasing SiO₂/Al₂O₃ ratio, the pathway of ethene formation is mainly enhanced. The present study is expected to provide guidance for the regulation of reaction pathways and future design of efficient bifunctional catalysts for complex heterogeneous reactions.