Evaluation of pyrolysis product of virgin high density polyethylene degradation using different process parameters in a stirred reactor

Abstract

The yield as well as molecular weight and composition of the condensed product generated from the HDPE was studied to gain insight into the role of temperature, equilibrium FCC catalyst, agitator speed and carrier gas on the pyrolysis products. Pyrolysis was done in a suite stirred bucchi stainless-steel autoclave reactor. The effect of process parameters such as degradation temperature, catalyst/polymer ratio (%), carrier gas type and stirrer rate on the condensed product yield and composition was determined. Reaction products were determined by GC analysis and shown to contain naphthenes (cycloalkanes), paraffins (alkanes), olefins (alkenes) and aromatics.The maximum “fuel like” condensed product yields were at 450°C and 10% catalyst, respectively.The influence of different types of carrier gasses with varied molecular weights and reactivity was studied. Hydrogen as a reactive carrier gas increased the condensed and paraffinic product yield. Appropriate heat transfer – by stirring – can increase the catalyst efficiency in a stirred reactor. It is demonstrated that the use of equilibrium FCC commercial catalyst under appropriate reaction conditions can have the ability to control both the condensed yield and carbon number distribution from HDPE degradation, and thus potentially decrease the process cost with more valuable hydrocarbons.