Thermocatalytic Conversion of Automotive Shredder Waste and Formation of Nanocarbons as a Process Byproduct

Thermocatalytic conversion of plastic wastes using titanium dioxide (TiO 2 ) is a novel and promising approach for waste management and sustainable production of materials. In this approach, the heat-treatment of a mixture of plastic waste and TiO 2 at elevated temperatures helps to achieve fast and complete decomposition and offers several advanced byproducts. In this study, the different physicochemical interactions between TiO 2 and an industrial plastic waste (i.e., automotive shredder residue, ASR) at elevated temperatures were investigated. The nonisothermal degradation kinetics of ASR, with and without TiO 2, were calculated from the thermogravimetric analysis (TGA) and results confirmed that the TiO 2 influences and catalyzes the degradation of ASR. The analysis of the resulting gas showed that the TiO 2 limits the formation of CO 2 gas, which is considered an unfavorable product of thermal processes, without changing the quality of the hydrocarbons (i.e., oils) generated during the heat treatment of ASR. While ASR decomposes, TiO 2 transforms into value-added Ti-based ceramics; this transformation generates a high yield of CO that can be collected for commercial purposes. In addition, TiO 2 led to the formation of considerable quantities of onion-like carbon nanoparticles (OLC-NPs) from the gas phase; this product was characterized and its formation mechanism was discussed.