Synergistic construction of bifunctional and stable Pt/HZSM-5-based catalysts for efficient catalytic cracking of n-butane

Efficient conversion of light alkanes is of essential significance for enhancing the utilization efficiency of resources and exploring the activation and evolution regulation of C-C and C-H bonds in stable molecules. The processes are often executed with catalysts under harsh conditions. The olefin yield and metal stability have been the long-standing concerns. Herein, we report a facile strategy of constructing a bifunctional Pt/HZSM-5-based catalyst by two-step atomic layer deposition (ALD) to achieve a high light olefin formation rate of 0.48 mmol g(cat)(-1)center dot min(-1) in the catalytic cracking of n-butane at 600 degrees C, which is similar to 2.2 times higher than that of the conventional Pt/HZSM-5 catalyst (0.22 mmol g(cat)(-1)center dot min(-1)). Moreover, the bifunctional Pt/HZSM-5-based catalyst exhibited outstanding recyclability and excellent metal stability against sintering in comparison with conventional Pt/HZSM-5. Detailed microscopic and spectroscopic characterization studies demonstrate that the metal oxide (TiO2 or Al2O3) coating not only prevents the metal from high-temperature sintering, but also regulates the proportion of coordinately unsaturated platinum surface atoms. Theoretical calculations further confirm the preference of nucleation of TiO2 or Al2O3 on coordinately unsaturated platinum sites, which in turn modulates the bifunctional dehydrogenation-cracking pathway to improve the olefin formation rate.

Automated summary

This study successfully achieved efficient conversion of light alkanes using a bifunctional Pt/HZSM-5-based catalyst, which exhibited outstanding recyclability and metal stability. The use of metal oxide coating not only prevented metal sintering, but also regulated the proportion of platinum surface atoms, leading to an improved rate of light olefin formation.