The effect of temperature, heating rate, initial cross-linking and zeolitic catalysts as key process and structural parameters on the degradation of natural rubber (NR) to produce the valuable hydrocarbons

Abstract

In this study, the effects of different zeolite based catalysts, initial crosslinking, temperature and heating rate as key process and structural parameters on the thermal degradation of natural rubber (NR) were investigated. The product composition containing liquid, gas and coke yield as well as the varied components of liquid product as a function of the studied parameters in the stirred reactor were compared. The degradation temperature, heating rate, initial crosslinking and catalyst type affected on the formation of aromatic and aliphatic products appreciably. The results showed that the thermal pyrolysis of natural rubber tended to follow the un-zipping and Diels-Alder mechanisms significantly though the catalytic pyrolysis reduced the unzipping share and enhanced the Diels-Alder reactions. Meanwhile, the results showed that the non-vulcanized sample produced the maximum condensed hydrocarbons at 450 °C and the medium heating rate in the studied range. The studied degradation mechanism using TGA instrument indicated that the ratio of crosslinking over chain scission and unzipping decreased with increase in temperature and heating rate. Generally, it showed that the double bond in the polymer structure beside the heating rate could played an important role in the degradation mechanism and the products. The results indicated that activation energy decreased with increasing the heating rate (171.06–136.51 kJ mol−1).