Effect of volatile reactions on oil production and composition in thermal and catalytic pyrolysis of polyethylene

•Yield and quality of the oil were investigated at various volatilization conditions.•A high volatilization temperature favors cracking of volatiles to form light oil.•Effect of volatilization time on oil is dependent on volatilization temperatures.•Volatile reactions hardly affect the carbon distribution of the oil after catalysis.•Alkenes are more than alkanes in oil and contribute to coke deposition on catalyst.