Optimization of Low-Temperature Catalytic Cracking of Polyolefin Waste in Open-Batch Reactors Using Zeolite Beta with Controlled Intrinsic Properties

Abstract

Abstract Environmental problems are worsening due to the complexity in managing plastic waste. Chemical recycling emerges as a pivotal technology that can suppress additional carbon introduction into the carbon cycle and provide petroleum alternatives for current petrochemical processes, leading to value-added products. The utilization of zeolites can significantly reduce energy consumption by lowering the operation temperature required for pyrolysis. Here, we demonstrate low-temperature catalytic cracking of polyethylene (PE) utilizing an open-batch reactor configuration and *BEA-type zeolite catalysts, maximizing the liquid product selectivity. With the optimized open-batch setup and zeolite properties, high PE conversion (~ 80%) and liquid selectivity (~ 70%) were achieved at a low temperature of 330°C, effectively reducing the irreversible coke formation. We systematically explored the effects of aluminum (Al) site density and zeolite crystal size, revealing that zeolite crystal size is another critical factor determining the liquid production from PE due to its reactant shape selectivity. This work not only demonstrates that an effective combination and optimization of reactor and catalysts can enhance the overall catalytic activity but also offers insights into designing catalysis systems for the catalytic recycling of polyolefin wastes.