Accurately tuning the pore size and acidity of mesoporous zeolites for enhancing the catalytic hydrocracking of polypropylene

Abstract

Catalytic hydrocracking of plastics is one of the appealing strategies for converting waste plastics into high-value chemicals and fuels, featuring environmental friendliness and economy. Zeolites are considered to be promising catalysts for plastic hydrocracking. But there is still a distance from practical applications due to obstacles, such as the unsatisfactory catalytic efficiency and unclear influences of the active sites of zeolites on the catalytic performance. Herein, we synthesized a series of Al-MCM-41 catalysts with regulable specific surface area, pore size, and acidity by a sol–gel method, which were used for catalytic hydrocracking of polypropylene (PP) to clarify the structure–performance relationship. The results showed that the specific surface area and pore size of the zeolite were positively correlated with the catalytic performance of PP hydrocracking. Additionally, it was found that the acidity of the zeolite exhibited a peak distribution. Al-MCM-41 has a high liquid fuel yield (70.23%) at a lower hydrocracking temperature (220 °C) and is an efficient catalyst for PP hydrocracking. Furthermore, it was observed that zeolites with larger pore size and specific surface area can prolong the life of zeolites. The research can give a better understanding of how to design higher-performance and long-life catalysts for chemical upcycling of waste plastics.