Integrating continuous-stirred microwave pyrolysis with ex-situ catalytic upgrading for linear low-density polyethylene conversion: Effects of parameter conditions

A continuous-stirred microwave pyrolysis (CSMP) reactor coupled with an ex-situ catalytic bed was developed for the conversion of linear low-density polyethylene (LLDPE) to high-grade fuels. Effects of catalyst-to-reactant ratio and feeding rate on product yield and chemical selectivity were studied. The CSMP of LLDPE produced up to 84.1 wt.% condensate product composed of hydrocarbon fuels. With the assistance of the ex-situ catalytic process with HZSM-5, more refined chemicals dominated by gasoline-range hydrocarbons (C5-C12 hydrocarbons) were observed. When the catalyst-to-reactant ratio was 15 % and the feeding rate was 6 g/min, the condensate oil with a high higher heating value (45.23 MJ/kg) showed the highest selectivity of gasoline-range hydrocarbons (98.0 %). The pyrolysis processes yielded ethylene as the main gas product. With the addition of HZSM-5, propylene and propane were the primary gas components. The plausible pathway for the conversion of LLDPE mainly proceeded through radical mechanism for pyrolysis and carbenium ion mechanism for catalysis was elaborated. The potential net energy gain increased from 34.16 MJ/kg to 48.91 MJ/kg with growing feeding rate from 6 g/min to 30 g/min.