Direct production of olefins from waste plastic using a pyrolysis and fluid catalytic cracking integrated process: Part 1. study on the production and analysis of waxy oil obtained using a new type of a fluidized bed reactor

Abstract

The ultimate aim of this research is to produce ethylene and propylene directly from waste plastic. To achieve this, we designed a new cracker having a fluidized bed reactor (FBR) and a fluid catalytic cracking (FCC) unit. The FBR produces oil in vapor phase, and the FCC unit transforms the vapor into olefins. As a first step toward achieving the research goal, the current study conducts pyrolysis of low-density polyethylene using a new pyrolysis process having a FBR. By understanding characteristics of pyrolysis oils obtained in this study, it becomes possible to determine its suitability as FCC feed and its relationship with olefin productivity. The current investigation focused on the effects of vapor residence time, reaction temperature, and type of fluidizing medium on yield and composition of oil. The results showed that the waxy oil yield depended highly on reaction temperature, reaching a maximum of about 95 wt%. The sum of yields of n-alkenes and n-alkadienes, which are favorable for producing olefins when catalytically cracked in the FCC unit, reached 82 wt%. SIMDIS analysis, which determines the boiling point range distribution of oil, revealed strong effects of reaction temperature and residence time on the carbon numbers of the waxy oil.