The in-situ effect of H2S on the decomposition of natural rubber and catalyst activity

Abstract

In this work, the pyrolysis of natural rubber (NR) under N₂ and H₂S atmosphere was performed to illustrate the possible effect of H₂S on NR decomposition with and without catalysts. A molecular dynamics simulation based on reactive force field (ReaxFF) was also conducted to understand the interaction mechanism between H₂S and intermediates from NR decomposition. Furthermore, the catalytic decomposition of NR under H₂S atmosphere and the adsorption characteristics of H₂S by zeolites alone were also carried out to investigate the effect of catalysts on sulfur behavior and the reversed effect of H₂S on catalyst activity. This work revealed that the introduction of H₂S can influence the yields of pyrolytic oil and gas, as well as composition of the oil. Combining experimental and simulation studies, H₂S can interact with intermediates from NR decomposition forming sulfur-containing substances in pyrolytic oil. The H₂S adsorption experiments by various catalysts revealed that catalysts can chemically adsorb H₂S. The introduction of Zn can promote the adsorption ability by reacting with sulfur-containing substances to generate ZnS, with the desulfurization effect following the order of 3Zn/ZSM5 > ZSM5 > 3ZnO/ZSM5.

Keywords: Catalytic pyrolysis; Desulfurization; Tire; ZSM; Zn.