Study on the pyrolysis characteristics and char gasification kinetics of pre-separated automobile shredder residues

Abstract

Automobile shredder residue (ASR) is a typical solid waste produced by the end-of-life automobile industry. The pyrolysis and gasification of ASR are effective methods to achieve reduction and resource utilization. By means of thermogravimetric analysis and fixed-bed experiments, the distribution as well as physicochemical properties of five typical ASR pyrolysis products after pre-sorting were systematically investigated, and the gasification kinetics of their pyrolysis char under CO2 as well as steam were also studied. Results showed that the pyrolysis of ASR was basically completed at 500°C, and the pyrolysis gas yield increased significantly with temperature. The tar contained mainly poly-benzene rings with carbon atoms C11–15 and their derivatives. At high temperatures, the structure of pyrolysis char tended to become more ordered, with small functional group such as - OH, - NH, - CH3, - CC -, and - COOH fracturing. The residual amounts of heavy metals such as Cr, Pb, and Ni in pyrolysis char were mostly exceed 45%, which were significantly affected by the type of heavy metals, pyrolysis temperature and material type. Hydrogen production from steam gasification accounted for up to 65%, and the gasification reactivity was better than that of CO2 gasification. The activation energy (E) calculated through shrinking core model (SCM) and random pore model (RPM) was 38.81–105.44 kJ/mol and 39.53–98.56 kJ/mol, respectively, which provided a good fit to the gasification kinetics in two gasification atmospheres. This study provides detailed data for the ASR pyrolysis and gasification technology, which is an important reference value for ASR research.