STEAM CRACKING OF UNCONVENTIONAL HYDROCARBON FEEDSTOCKS FOR PRODUCTION OF PETROCHEMICALS

The thermal decomposition of polyalkenes was investigated as a recycling route for the production of petrochemical feedstock. Individual polyalkenes (LDPE, HDPE, LLDPE, PP) and their mixtures, possibly with small addition of PVC and PS were thermally decomposed in a batch reactor at 450°C, thus forming oil/wax products. Then these products were dissolved in primary heavy naphtha to obtain steam cracking feedstock. The selectivity of products and kinetics of copyrolysis for eight different solutions of oils/waxes in the temperature range from 740 to 820°C at residence times from 0.1 to 0.55 s were studied. An overview of obtained results will be given. The influence of hydrocarbons structure on the cracking mechanism and on the yields of desired low molecular alkenes during copyrolysis will be presented. In addition to the primary reactions, the secondary reactions leading to coke formation have also been studied. The formation of coke during copyrolysis of seven different solutions of oils/waxes is compared with coke formation from individual naphtha.