Abstract:
Catalytic pyrolysis of polymer waste is an attractive alternative process for the conversion of large hydrocarbon compounds to useful products for the most reliable fueling and valuable chemicals, growing toward a circular economy and enhancing the reduction of waste materials. In this study, catalytic pyrolysis of waste polyethylene wax (WPEW) using a dual acid- acid catalyst and acid-base catalyst, which had various pore size distributions and included a strong active site, maximized the desirable yield and product distribution. The effect of the process conditions and synergy of activated carbon (AC) blended into both a spent fluid catalytic cracking catalyst (FCC) and magnesium oxide (MgO) catalyst was examined in a 3000 cm3 custom-built reactor at varying operating temperatures (400-470°C), inert nitrogen gas flow rates (50 mL min-1), catalyst loading (1-5 wt %), and FCC-AC and MgO-AC ratios in the catalytic conversion of WPEW to obtain the highest amount of diesel-like oil. The results indicated that thermal cracking of WPEW at 420°C by a fixed inert N2 flow rate of 50 mL min-1obtained the highest liquid yield of 81.64 wt % and a diesel-like fraction of 35.51 wt %, while the catalytic conversion of WPEW under optimum conditions (temperature: 420°C; fixed inert N2 flow rate: 50 mL min-1; catalyst load: 5 wt %; MgO-AC ratio: 0.5:0.5) achieved the highest liquid diesel-like yield of 41.92 wt %. Physicochemical analyses showed that the highest heating value of WPEW pyrolytic oil was 44.20 MJ kg-1, and the viscosity was 1.7 mm2 s-1at 40°C. The combination of MgO-AC as a dual catalyst illustrates a positive synergistic effect on the catalytic activity performance markedly, outstanding catalytic characteristics alongside high selectivity in pyrolysis of WPEW to paraffinic hydrocarbons in the diesel-like fraction. © 2022 American Chemical Society. All rights reserved.