Effect of temperature on the pyrolysis of plastic waste using zeolite ZSM-5 using a refinery distillation bubble cap plate column

Abstract

The use of plastic is increasing every year, causing an accumulation of plastic waste that is detrimental to the environment. The purpose of this work is to determine the effect of temperature on the conversion of plastic waste into alternative energy through a pyrolysis-catalytic cracking process, using ZSM-5 as a catalyst, and pyrolysis product refinement using a distillation bubble cap plate column. In this study, the raw materials were polypropylene obtained from plastic waste and the catalyst zeolite ZSM-5 (500 ​g ​PP/50 ​g ZSM-5). A fixed bed reactor (D/H ​= ​1/4) was used under vacuum conditions (−3 ​mm ​H2O) to minimize the oxygen content in the reactor. The plastic waste degraded into vapor in the pyrolysis reactor and traveled through a distillation bubble cap plate column consisting of 4 trays that used reactor heat between 500 and 560 ​°C. It was found that the optimum liquid oil (68.43 ​wt%) was obtained at 560 ​°C, and based on API gravity, this oil consisted of gasoline on tray 1 (500–560 ​°C), tray 2 (500–600 ​°C), and tray 3 (580–620 ​°C). Kerosene was obtained on tray 2 (520–650 ​°C), tray 3 (620–650 ​°C), and tray 4 ​at 650 ​°C. The pyrolysis-catalytic cracking process using ZSM-5 at temperatures above 560 ​°C yielded a higher amount of gas, while the thermal process at temperatures above 580 ​°C yielded a high amount of wax polymer. The analysis results of the oil-fuel characteristics of density, calorific value, octane number, and function group, showed similar properties to those of fossil fuels.