Rubber waste tyre: Effect of temperature on pyrolysis char yield and properties

Abstract. Waste tyre pyrolysis is a viable technology to convert tyres into useful products such as pyrolysis oil, fuel and gas. Most of the research focus on investigating the effect of pyrolysis operating parameters on the oil product. With the increasing applications of the solid char produced, it is found that no detailed investigation on the effect of pyrolysis temperature on the char yield and properties. Thus, this project is aimed to determine the effect of pyrolysis temperature on tyre- derived char yield and properties. A total of three char samples were produced from rubber crumb, namely Char400, Char550 and Char700, corresponding to their pyrolysis temperature at 400°C, 550°C and 700°C respectively. Rubber crumb and these 3 char samples were sent to Fourier Transform Infrared Spectroscopy (FTIR), Elemental analysis of carbon, hydrogen, nitrogen and sulphur (CHNS), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis for characterization purposes. It was found that increasing temperature from 400°C to 700°C led to significant char yield reduction from 76% to 36.25%. In terms of composition, Char400 has additional alkane and phenol functional groups indicating the main constituents in rubber crumb did not decompose completely at low temperatures. Furthermore, char produced at higher temperatures has lower carbon content, higher sulphur content, higher specific surface area, lower average pore width and more structured surface morphology. Overall, temperature affects char yield and properties significantly.