Conversion of low density polyethylene into fuel through co-processing with vacuum gas oil in a fluid catalytic cracking riser reactor

• Mixtures of vacuum gas oil (VGO) and low density polyethylene (LDPE) were processed.
• A fluid catalytic cracking riser reactor was used.
• The influences of processing parameters on product yield patterns were presented.
• The different compositional distributions of the obtained products were presented.
• Non-conventional VGO/LDPE feed co-processing in FCC unit is viable.

In this work, mixtures of vacuum gas oil and low density polyethylene, a major component of common industrial and consumer household plastics, were pyrolytically co-processed in a fluid catalytic cracking (FCC) riser reactor as a viable alternative for the energy and petrochemical revalorisation of plastic wastes into valuable petrochemical feedstocks and fuel within an existing industrial technology. Using equilibrium FCC catalyst, the oil–polymer blends were catalytically cracked at different processing conditions of temperatures between 773 K and 973 K and catalyst feed ratios of 5:1, 7:1 and 10:1. The influence of each of these processing parameters on the cracking gas and liquid yield patterns were studied and presented. Further analysed and presented are the different compositional distributions of the obtained liquids and gaseous products. The analysis of the results obtained revealed that with very little modifications to existing process superstructure, yields and compositional distributions of products from the fluid catalytic cracking of the oil–polymer blend in many cases were very similar to those of the processed oil feedstock, bringing to manifest the viability of the feedstock co-processing without significant detriments to FCC product yields and quality.