Composite zeolite beta catalysts for catalytic hydrocracking of plastic waste to liquid fuels

Abstract

Abstract The conversion of model waste plastic mixture into high-value liquid product was studied in the presence of hydrogen and composites of zeolite beta catalysts. For the sake of comparison, the conversion of actual waste plastic mixture and high-density polyethylene was also carried out. The composite zeolite beta catalysts were synthesized using a range of silica-to-alumina ratios, alkali concentrations, and hydrothermal treatment times. SEM, EDX, XRD, N2-BET, FTIR, and py-FTIR were used for the characterization of the catalysts. The catalytic experiments were conducted in a 500 ml stirred batch reactor at 20 bar initial cold H2 pressure and the temperature of the reaction was varied between 360 and 400 °C. The two composite catalysts, BC27 and BC48, prepared without alkali pretreatment were found to be the most suitable catalysts. With BC27 and BC48 at 400 °C, 93.0 wt% conversion was obtained with actual plastic mixture and the liquid yield exceeded 68.0 wt%. Experiments with the regenerated catalysts showed their performance comparable to the fresh catalysts.

Keywords

• Chemical recycling
• Plastic conversion
• Waste plastic
• Zeolite beta
• Composite catalyst