Nickel promoted Si-rich ZSM-5 nanocatalyst remarkably converts LDPE plastic waste to gasoline range hydrocarbons in a dual-bed semi-batch reactor at atmospheric pressure

Abstract

Catalytic pyrolysis is an environmentally friendly recycling method, which has attracted remarkable attention due to worldwide issues of the production and accumulation of plastic wastes. In this work, the catalytic pyrolysis of Low-density polyethylene (LDPE) was carried out in a dual-bed semi-batch reactor over the Si-rich Ni/ZSM-5 nanocatalyst at atmospheric pressure. The parent nanocatalyst was prepared by hydrothermal technique and modified with nickel promoter (0–25 wt%). The properties of the nanocatalysts were characterized by XRD, FTIR, FE-SEM, EDX, TEM, BET, NH3-TPD, and TG-DTA techniques. The results showed the high crystallinity, spherical particles, and high specific surface area (376 m2g−1). The impact of operational conditions was evaluated to maximize the production of the high value-added compounds. The high percentage of the Ni promoter (25 wt%) led to the highest amount of gasoline range hydrocarbons (61%). The appropriate operational conditions were temperature of 525 °C, catalyst to plastic ratio of 1:20, and 2.5 ml min−1 nitrogen flow rate, resulting in the best product distribution: aromatics (39.4%), olefins (28.3%), and paraffins (15%). The reusability of the nanocatalyst showed high performance and more aromatic production. The characterization results of the used nanocatalyst confirmed the high stability through the pyrolysis reaction and lack of significant structural defect. The developed nanocatalyst represented the high activity through the pyrolysis of the real LDPE plastic waste, including the major product distribution in the gasoline range hydrocarbons.