Hydrogen Pressure as a Key Parameter to Control the Quality of the Naphtha Produced in the Hydrocracking of an HDPE/VGO Blend

The hydrocracking of high-density polyethylene (HDPE) blended with vacuum gas oil (VGO) has been studied to assess the effect of H2 pressure on the yield and composition of the products and with the aim of obtaining commercial fuels, mainly naphtha. The experiments have been performed using a PtPd/HY catalyst in a semibatch reactor under the following conditions: H2 pressure, 20–110 bar; 440 °C; catalyst to feed ratio, 0.1 gcat (gfeed)−1; HDPE to total feed ratio, 0.2 gHDPE (gfeed)−1; and reaction time, 2 h. The composition of the main fractions produced (gas, naphtha, and light cycle oil) reveals the interest in carrying out the process at 110 bar. Thus, conversions of 96 and 79% for the removal of heavy hydrocarbons and the removal of HDPE molecules have been obtained, respectively, together with a yield of naphtha of 53.4 wt%. This naphtha is mainly paraffinic, and it has a RON of 91.5 (within the commercial standards). Furthermore, three fractions have been observed in the analysis (temperature-programmed oxidation) of the coke. This analysis reveals that at 110 bar, the coke retained in the HY zeolite cages is less developed and burns at a moderate temperature.