Total utilization of waste tire rubber through pyrolysis to obtain oils and CO2 activation of pyrolysis char

• Waste tire rubber was successfully pyrolyzed to mainly produce oil and char.
• Pyrolysis char was successfully activated using CO2 to produce activated char.
• The maximum surface area of activated char was 437 m2/g.
• The sulfur contents of the pyrolysis oils were 0.85–0.96 wt.%.
• Acid treatment of pyrolysis char strongly decreased the ash and sulfur contents.

Waste tire rubber (WTR) was pyrolyzed in a fixed bed reactor in the final temperature range of 500–800 °C. Pyrolysis oils were analyzed both quantitatively and qualitatively. Pyrolysis chars obtained were activated using CO2 at a final temperature of 950 °C with a final activation time of 1–3 h. In addition, the influence of the acid treatment of pyrolysis char on the physicochemical properties was investigated. In the experiments, the yields of pyrolysis oil and pyrolysis char were 30–38 and about 37 wt.%, respectively. The pyrolysis oils consisted mainly of limonene, aromatic hydrocarbons such as xylene, and some heteroatom-containing compounds, such as benzothiazole and 2,4-dimethylquinoline. The sulfur contents of the pyrolysis oils were 0.85–0.96 wt.%. Most of the sulfur remained in the pyrolysis char. The maximum surface area of the activated char obtained by CO2 activation was 437 m2/g. The acid treatment of the pyrolysis char decreased the ash and sulfur contents, which supported the strong potential of the acid-treated char for use in commercial applications.