A six-lump kinetic model for HDPE/VGO blend hydrocracking

A six lump-based kinetic model has been developed for the hydrocracking of high-density polyethylene (HDPE) blended with vacuum gas oil (VGO) over a PtPd/HY zeolite catalyst. The blend (20 wt% HDPE and 80 wt% VGO) has been hydrocracked in a semi-continuous stirred tank reactor under the following conditions: 400-440 degrees C; 80 H-2 bar; catalyst to feed (C/F) weight ratio, 0.05-0.1 g(cat)g(feed)(-1); reaction time, 15-120 min; and stirring rate, 1300 rpm. The kinetic model, which is an approach to tackle the complex reaction mechanism behind the hydrocracking of a HDPE/VGO blend, predicts the evolution over time of product distribution (gas, naphtha, light cycle oil (LCO), heavy cycle oil (HCO), HDPE and coke). The kinetic model and its computed parameters have been used for the simulation of the HDPE/VGO hydrocracking establishing that a C/F ratio of 0.075 g(cat)g(feed)(-1) and temperature-time combinations of 430 degrees C-10 min and 440 degrees C-70 min are the optimal operating conditions. Under these conditions, a proper balance between the HCO conversion (>80 %), HDPE conversion (>60 %) and liquid fuel production index (>1.0) would be obtained. This kinetic model could serve as a basis for scaling-up in the valorization of waste plastics by co-feeding them to industrial hydrocracking units, within a Waste-Refinery strategy.

Automated summary

A six lump-based kinetic model was developed to predict the hydrocracking process of a blend of high-density polyethylene (HDPE) and vacuum gas oil (VGO). The model identified the optimal operating conditions for achieving high conversion rates and liquid fuel production.