(305d) A Novel Aluminosilicate Zeolite for Efficient Catalytic Pyrolysis of High-Density Polyethylene for High Yields of Gasoline Range Hydrocarbons

Plastic products are essential across numerous industries due to their durability and versatility. The recycling rate of plastic waste, however, remains low, leading to significant environmental challenges. The urgency of the plastics pollution problem has prompted the research community to develop advanced technologies enabling recycling and upcycling. Pyrolysis is an economically viable approach for plastic waste management. High-density polyethylene (HDPE) is a thermoplastic widely used in various applications. One major limitation for HDPE pyrolysis is the wide range of products formed and low product selectivity. To address this challenge, researchers have been testing different catalysts for HDPE pyrolysis, particularly zeolites due to their popularity in existing petrochemical processes.

In this work, a novel zeolite, ZEO-1, was studied for HDPE pyrolysis using a microreactor.¹ ZEO-1 has a high silica content with larger pores than common zeolites and a large surface area, having shown excellent heavy-oil conversion and selectivity to fuels by fluid catalytic cracking. Our work compares the performance of ZEO-1 against other common zeolites, such as ZSM-5 and beta. We observed that HDPE pyrolysis using ZEO-1 gave approximately 60 wt% gasoline yield at 500 ^oC at vacuum. This yield was 15 and 20% higher than that using ZSM-5 and beta catalysts, respectively, although all zeolites helped achieve higher HDPE conversion and gasoline yields compared to neat pyrolysis. Increasing system pressure reduced the benefit of using ZEO-1, although it still provides benefits. Our findings pave a way to the advancement of new strategies of waste plastic management by novel catalyst design.

1. Lin, Q. F.; Gao, Z. R.; Lin, C.; Zhang, S.; Chen, J.; Li, Z.; Liu, X.; Fan, W.; Li, J.; Chen, X.; Camblor, M. A.; Chen, F. J., A stable aluminosilicate zeolite with intersecting three-dimensional extra-large pores. Science 2021, 374 (6575), 1605-1608.