Thermal conversion of polyethylene into liquid hydrocarbons

Abstract

This study examines the catalytic depolymerization process for extracting liquid hydrocarbons from polyethylene wastes, which aims to reduce the country of Uganda's rising polyethylene waste production while simultaneously examining its effects on the rest of the world. A survey was conducted to determine the most popular and widely used polythene bag in the Kikuubo and Nankulabye markets and the findings revealed that the black medium-sized polythene bag was the most popular. The liquid hydrocarbons were isolated from the black medium sized polythene bags through catalytic depolymerization. As part of the experiment, it was necessary to compare the yield from both new and waste polythene bags, so polythene bags were retrieved from disposal sites and new polythene bags were purchased. In order to prepare the waste polythene bags for catalytic depolymerization, they were cleaned, weighed, and shred. The shredded polythene bags were subjected to pyrolysis in the presence of a catalyst (sodium bicarbonate) at 200°C while the residence time was gradually increased to create vapor that was condensed to yield pyrolytic oil (liquid hydrocarbons); the same process was repeated for the new polythene bags. The yield of the pyrolytic oil was 41.37% and 40.53% for new polythene bags and waste polythene respectively. The pyrolytic oil was a light green color; examinations of its viscosity, density, calorific value, and GC/MS data revealed that it had the following properties: an aniline point of 81°C, a viscosity of 2.29cSt, a calorific value of 21.31MJ/kg, and a hydrocarbon range of C5 to C27. The results suggest that the black polythene bag has the capabilities of generating liquid hydrocarbons which is a promising source of energy for light load machines. A higher yield could have been obtained if a reaction vessel made out of a good conductor was used and temperatures were not limited to 200°C.