Preparation of Petrochemical Feedstock from Rubber Wastes by Thermal Solvolysis

Abstract

The thermal decomposition of crumb rubber based on isoprene pure rubber in an autoclave in various media such as toluene, isopropyl alcohol, and water has been studied. The highest degree of conversion of pure rubber is achieved in a toluene medium, while the lowest is in water. The formation of a gas is minimum in the aqueous medium and maximum in a medium of isopropyl alcohol; however, the yield of the gaseous products is much lower than in the processes of high-temperature pyrolysis of rubber. The fractional composition of the liquid products varies within a wide range, namely, more gasoline fractions are formed in the medium of toluene; oil fractions, in water; and middle distillates predominate in the products obtained in the isopropyl alcohol medium. The concentration of dipentene and p-cymene, which may be of interest as the feedstock for industrial organic synthesis, in the distillate fractions reaches 10–16 wt %. Unsaturated aliphatic structures predominate in the oil fractions obtained in the medium of water or isopropyl alcohol, while alkylbenzenes predominate in the “toluene” oils. The oil fractions can be of interest as a feedstock for the production of both lubricating and process oils. The solid carbonaceous residue from the thermal solvolysis of rubber contains not only untransformed carbon black, but also zinc oxide and sulfide, so that it can be sent to the production of zinc or be reused as a rubber filler.