Adjusting effects of pyrolytic volatiles interaction in char to upgrade oil by swelling waste nylon-tire

Abstract

Waste nylon-tire (WNT) is a typical solid municipal waste, pyrolysis efficiently disposes WNT to produce oil containing high-value chemicals. Upgrading the quality of oil is the key to improve WNT pyrolysis economy. Herein, swelling was applied to pretreat WNT, and swelled waste nylon-tire (SWNT) was pyrolyzed at different temperatures (400 °C-600 °C). Lower than 500 °C, swelling pretreatment realized the number of compounds in oil by GC-MS decreased 59.57% at 400 °C (60.78% at 450 °C, 67.97% at 500 °C) compared to Waste nylon-tire pyrolytic oil (TPO). Over 500 °C, this phenomenon weakened, decreased 47.67% at 550 °C (11.48% at 600 °C). At 400 °C and 450 °C, long chain methyl esters yield was over 30 A.% instead of short chain alkanes in TPO. D-limonene yield was over 20 A.% in oil of swelled waste nylon-tire (STPO). From 500 °C to 600 °C, swelling pretreatment affected the relative content of BTX and PAHs. At 500 °C and 550 °C, the relative content of BTX in STPO was more than twice of TPO, and BTX reached 28.75 A.% at 600 °C. PAHs in STPO appeared at 500 °C higher than TPO (450 °C), and PAHs was 0.73 A.% at 500 °C. Swelling pretreatment could produce more larger pores in particle during pyrolysis, which sharply inhibited the interaction of volatiles inside tire, so the number of compounds in oil sharply decreased at lower temperatures. Over 550 °C, temperature became the dominant role for generating oil, and components tended to be similar for STPO and TPO. CS₂ with high-volatility released quickly from WNT during pyrolysis, it could be recycled to reduce final cost and environment impacts.

Keywords: Compounds; Pyrolytic oil; Swelling pretreatment; Volatiles interaction; Waste nylon-tire.