Research progress in pyrolysis theory and technology of waste tires

The enormous number of vehicles and the industrial system generate large quantities of waste tires， and pyrolysis is considered to be an effective means of treating waste tires. This paper focuses on the current research status of waste tire pyrolysis technology， summarizes the composition and formation mechanism of waste tire pyrolysis products， and analyses the factors restricting the resource utilization of pyrolysis products and the methods to enhance the resource utilization of pyrolysis products， and puts forward the bottleneck problems that need to be broken through for the industrial application of waste tire pyrolysis technology in the future. Pyrolysis of waste tires produces a range of products such as fuel gas， oil and carbon， as well as other valuable chemicals such as limonene， benzene， toluene， ethylbenzene and others. Existing studies have indicated that the distribution of pyrolysis products from waste tires is determined by the degree of primary and secondary reactions in the pyrolysis process， and the degree of primary and secondary reactions is affected by process parameters such as temperature， heating rate， volatile retention time， pressure， reactor structure， catalysts and material particle size， among which temperature has the greatest influence on the distribution of pyrolysis products. The increase of temperature is conducive to the formation of H2， CH4， CO， benzene， toluene， ethylbenzene and xylene， and promotes the conversion of limonene to aromatics and the conversion of sulfur from pyrolysis oil and gas to pyrolysis carbon. In order to realize the industrial application of waste tire pyrolysis technology， further research work should be carried out in the accurate construction of pyrolysis kinetic models， the development of highly selective catalysts and the design of pollutant treatment schemes.