Recovery of fuel liquid from plastic waste using Ni/ZSM-5 catalyst by distillation bubble cap plate column

Abstract

The valorization of polypropylene (PP) plastic waste into high-value liquid fuels via catalytic pyrolysis represents a promising pathway toward sustainable waste-to-energy conversion. This study investigates the optimization of liquid fuel yield using a bifunctional Ni/ZSM-5 catalyst synthesized through impregnation. A total of 500 g of waste PP and 50 g of Ni/ZSM-5 (PP:Ni/ZSM-5 = 10:1) were processed in a stainless-steel fixed-bed semi-batch reactor over a temperature range of 420–580 °C. The evolved vapors were fractionated through a four-tray distillation bubble-cap column and condensed at ±5 °C. The Ni/ZSM-5 catalyst significantly enhanced cracking activity, enabling high liquid fuel recovery at lower operating temperatures. The best-performing temperature identified in this study was 480 °C, which yielded 77 wt.% liquid oil and 17 wt.% fuel gas whereas further heating beyond this point favored secondary cracking, converting liquid fractions into gaseous products. Fractional distillation revealed kerosene-range hydrocarbons in trays I–II and gasoline-range fractions in trays III–IV, indicating selective hydrocarbon distribution. These results demonstrate that Ni/ZSM-5 offers dual functionality for efficient cracking and aromatization, thereby improving product selectivity and energy recovery. The findings underscore the potential of catalytic pyrolysis as a scalable strategy for transforming plastic waste into alternative liquid transportation fuels while reducing environmental burden.