Sulfur self-doped char with high specific capacitance derived from waste tire: Effects of pyrolysis temperature

Qiangqiang Ren; Ziyue Wu; Song Hu; Limo He; Sheng Su; Yi Wang; Long Jiang; Jun Xiang

doi:10.1016/j.scitotenv.2020.140193

Sulfur self-doped char with high specific capacitance derived from waste tire: Effects of pyrolysis temperature

Sci Total Environ. 2020 Nov 1:741:140193. doi: 10.1016/j.scitotenv.2020.140193. Epub 2020 Jun 17.

Authors

Qiangqiang Ren¹, Ziyue Wu², Song Hu³, Limo He⁴, Sheng Su⁵, Yi Wang⁵, Long Jiang⁶, Jun Xiang⁵

Affiliations

¹ State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
² China-EU Institute for Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan 430074, China.
³ State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; China-EU Institute for Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan 430074, China. Electronic address: husong_hust@hotmail.com.
⁴ State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. Electronic address: limo_615@163.com.
⁵ State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; China-EU Institute for Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan 430074, China.
⁶ State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Department of New Energy Science and Engineering, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.

PMID: 32615423
DOI: 10.1016/j.scitotenv.2020.140193

Abstract

Preparation of sulfur self-doped char derived from waste tire (WT) was realized via two successively processes of pyrolysis and activation treatment. WT was firstly pyrolyzed at 400 °C, 600 °C, 800 °C, and 1000 °C to collect waste tire chars (WTCs) and they were subsequently activated at 800 °C with potassium ferrate (K₂FeO₄). The specific capacitance of activated waste tire chars at different pyrolysis temperatures (AWTCs-x-800) decreased from 92.60 F/g to 54.05 F/g at 1 A/g with pyrolysis temperature rising from 400 °C to 1000 °C. As for AWTCs-x-800, higher pyrolysis temperature promoted pore-forming process before 800 °C, and higher pyrolysis temperature enlarged pores after 800 °C. Increase of pyrolysis temperature promoted decomposition of alkyl-aryl CC bonds, transformation of relative small to large aromatic ring system, ordered arrangement of carbon atoms. Besides, it was found that sulfur doping content dominated in specific capacitance performance before 800 °C while surface area dominated after 800 °C. The large surface area and high S 2p_3/2 (-C-S-C-, sulphide bridge) content were beneficial for the larger specific capacitance while more S 2p_5/2 (-C-SOx-C- (x = 2-4, sulphone bridge) had the negative effect. Pyrolysis mainly affected sulfur doping properties, lower pyrolysis temperature promoted sulfur enrichment and S 2p_3/2 generation. Activation promoted surface area improvement and sulfur conversion, higher pyrolysis temperature promoted surface area improvement and sulfur release before 800 °C while the promotion effects weakened after 800 °C, and sulfur transformation of S 2p_3/2 converting to S 2p_5/2 strengthened at higher pyrolysis temperature.

Keywords: Char; Pyrolysis temperature; Specific capacitance; Sulfur; Waste tire.