Influence of Reaction Temperature and Heating Rate on the Pyrolysis Products of Rice Husk

Rice cultivation generates a substantial amount of rice husks (RH) as agricultural waste from rice milling, which is not effectively utilized for environmentally friendly products. This study investigates the product yields and chemical characteristics of RH pyrolysis conducted at temperatures between 400 and 600 °C, at 50 °C intervals, with heating rates of 5, 10, and 20 °C/min. The highest liquid product yield (30.57%) was achieved at 600 °C under a heating rate of 20 °C/min. Gas chromatography–mass spectrometry (GC–MS) characterization revealed that the liquid product consisted predominantly of complex mixtures, with C6 compounds dominating the carbon number distribution, followed by C8 and C5 compounds. During the pyrolysis process, CO2 and CO were the main components of the non-condensable gases, whereas total hydrocarbons (THC) were generated at pyrolysis temperatures of 500 °C and above. The carbon content of biochar increased as the pyrolysis temperature increased, while the oxygen and hydrogen contents decreased. These findings elucidate the influence of temperature and heating rate on the chemical properties of pyrolysis products derived from RH. In addition, the kinetic analysis of RH pyrolysis showed that the estimated activation energy varies depending on the applied method. Therefore, the combined use of multiple methods is considered desirable for providing a more reliable kinetic interpretation of RH pyrolysis.