Influence of Channel, Construction and Brønsted Acid Sites on the Catalytic Conversion Pathways of Isobutane Over MFI, TON and RFE Zeolites

Despite thorough exploration of the acidity properties and pore structure effects of zeolite catalysts on catalytic conversion, a comprehensive understanding of how these factors influence reaction pathways is still lacking. Herein, three common zeolites (ZSM-5, ZSM-22 and ZSM-48) of different shapes and size dimensions were introduced into catalytic conversion of isobutane, with combination of X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption and desorption, solid-state ²⁹Si and ²⁷Al MAS NMR, ammonia temperature programmed desorption (NH₃-TPD) and pyridine adsorption infrared spectroscopy (Py-FTIR) to characterize their structure and acidity. And channels and topologies were associated with stability and catalytic activity. ZSM-5 performed best, showing the most active sites. Furthermore, ZSM-48 led to an increase in the propene yield by suppressing inhibitory secondary reactions in the monomolecular reaction pathway. Moreover, the amount of Brønsted acid sites (BASs) of ZSM-22 were a key factor in promoting light alkene formation. However, 1D channels contributed to the deactivation of ZSM-22 and ZSM-48. The detailed reaction pathways of zeolite catalysts with diverse pore structures and acidities are crucial for optimizing their catalytic performance.

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