Influence of Gas-Phase Reactions on the Product Yields Obtained in the Pyrolysis of Polyethylene

Abstract

The characterization of the product fractions obtained from the pyrolysis of polyethylene (PE) in a laboratory-scale fixed bed reactor was performed. The experimental system allowed quantitative information to be obtained on the global tar, char, and gas yields. Pyrolysis runs were performed using reactor temperatures ranging between 500 and 800 °C. The influence of the residence times in the reactor of the primary volatiles generated by the pyrolysis process was also discussed. The secondary reactivity of the tar originated from PE pyrolysis was examined. A lumped-parameters approach was used in order to evaluate the global kinetic parameters for the gas-phase tar-cracking process. PE tars resulted to be more refractory to thermal decomposition than those obtained in the pyrolysis of biomass and lignocellulosic materials, but more reactive than tars obtained in the pyrolysis of coal.

Evolution of products during the degradation of polyethylene in a batch reactor

“…As previously shown, the yield of paraffins decreases with the increase in temperature. According to various authors [21,25,26] this fact could indicate the presence of repolymerization reactions that lead to an increase in hydrogen content in the evolved gas and a higher degree of unsaturation in the products obtained.…”

Microwave Pyrolysis of Plastic Wastes

“…It is known [90,91], that the final yield and hence product composition of pyrolysis products are determined mainly by the secondary and tertiary reactions that occur after the polymer molecules have first been cracked. Considering this and the increase in the reaction rate with temperature, the results in Table 21.2 are explained as follows: for the microwave pyrolysis results, as temperature increased, the reaction rate increased with the consequent increase in the production rate of primary gaseous products.…”

Equivalent Reactor Network Model for Simulating the Air Gasification of Polyethylene in a Conical Spouted Bed Gasifier

“…The gas consists commonly of 3.9 wt % H 2 , 14.3 wt % CH 4 , and 81.8 wt % C 2+ , whereas the char was found to be mainly composed of carbon. 21,27 The typical yield distribution of the pyrolysis products was coded in the ERN model using FORTRAN modules.…”