Comparative study on the desulfurization of powdered rubber and an aliphatic thiol

Abstract This study investigates the comparative desulfurization process of waste rubber powder and 1-butanethiol through reactive adsorption, using a Cu nanoparticle-based adsorbent deposited on an activated carbon support. The adsorbent was characterized by particle size analysis, textural analysis, FTIR spectroscopy, and X-ray diffraction, revealing a monomodal distribution of copper particles, a high specific surface area, and the presence of copper compounds on the support surface. Experimental results showed a significant difference in the desulfurization efficiency between the two compounds. The desulfurization conversion for butanethiol was nearly complete at 220 °C, whereas for rubber powder, the conversion was below 10% within the same temperature range. Increasing the temperature to 280 °C resulted in a doubling of the rubber powder conversion, but it remained significantly lower than that achieved for butanethiol. This difference is attributed to the limited accessibility of the adsorbent to sulfur atoms in the cross-linked polybutadiene structure, compared to the high accessibility in the case of 1-butanethiol. Therefore, the use of copper nanoparticles deposited on activated carbon proved to be efficient in the desulfurization of 1-butanethiol but showed limitations in the case of vulcanized rubber, where the accessibility of sulfides to the adsorbent was restricted by the macromolecular structure of the polymer.