Infrared heated co-pyrolysis behavior of polyethylene and corn stover via optimization of secondary reactions

Abstract

Infrared-fast pyrolysis (IF) has proven effective for examining the co-pyrolysis behavior of polyethylene (PE) and corn stover (CS) by optimizing secondary reactions. In this study, a fixed-bed reactor with fast infrared heating was adopted to explore the distribution of pyrolysis products and compare the product compositions generated by IF with those produced by electric-conventional slow pyrolysis (ECS). Increasing the PE ratio first increased the oil yield and then reduced it at 600 °C during the co-pyrolysis process by IF. The maximum oil yield produced by IF in PE50%-CS50% was 1.6 times the calculated yield, whereas the oil generated by ECS were roughly comparable to the calculated amount. Owing to the sluggish heating rate in ECS, the pyrolysis volatiles experienced a prolonged residence time in the high-temperature area, resulting in a severe secondary reaction and large variations in H2 and CO2 content. The highest H2 content in PE75%-CS25% was 18.09 vol%, which was 3.4 times the calculated value. The lowest CO2 content was 45.7 vol% in PE50%-CS50%, which was 27% less than predicted. During IF, The phenols, ketones, acids, aldehydes, and polyaromatic rings gradually decreased as the PE ratio increased, while the alcohol and ester content initially increased and then decreased. The alcohol reached a maximum content of 57.3% in CS50%-PE50%, while the ester reached a maximum value in PE25%-CS75%. The increased PE content produced a large number of hydrogen radicals that accelerated the hydrogenation and deoxygenation reactions of phenols and furans.