Research on the characteristics of pressured pyrolysis products of marine plastics

Abstract

The problem of marine plastic pollution, mainly composed of polyolefin plastics, is becoming increasingly serious, and reducing marine plastic pollution is urgent. Pyrolysis, as a promising technology for treating polyolefin plastics such as polystyrene (PS), has great potential in addressing marine plastic pollution issues. In order to explore the possibility of resource utilization of marine plastics, this article studied the effect of pressure changes on the pyrolysis products of marine plastics. Marine PS was prepared by soaking routine PS in artificial seawater and air drying, and the most significant difference between the two was found to be the salt attached to the surface. The dynamic characteristics of marine PS were analyzed using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, and the apparent activation energy of marine PS calculated by FWO and KAS methods are 102.94 kJ·mol−1 and 95.76 kJ·mol−1, respectively. The effect of pressure at different temperatures on the pyrolysis products of marine PS was studied. The results indicate that the yield of pyrolysis oil decreases as the pressure is increased, while solid products are obtained from scratch. The increase in pressure will gradually make the composition of the thermolytic gas become monotonous. Under critical pressure, pressurization promotes an increase in CH4 content while reducing H2 content, causing the lower heating value of pyrolysis gas to increase to 4.355 kJ·g−1. Analysis of oil content found that increasing pressure promotes the growth of Benzene Toluene Ethylbenzene & Xylene (BTEX) to 33.61%, but excessive pressure can significantly reduce the higher heating value from 42.116 MJ·kg−1 to 31.825 MJ·kg−1. The solid products were characterized using FTIR and it was found that pressure did not have a significant impact on surface functional groups. Increasing the pressure properly promotes the agglomeration of amorphous carbon.