Conversion of plastics/HVGO mixtures to fuels by two-step processing

A blend containing 20 wt.% low density polyethylene (PE) and 5 wt.% polyvin ylchloride (PVC) in heavy vacuum gas oil was pyrolyzed at 623 K (dechlorina tion step). This mixture was then thermally and catalytically cracked in th e presence of hydrogen at 673-723 K in a batch reactor (hydrocracking step) . The liquid products from hydrocracking contained no chlorine compounds al though the chlorine amount in the dechlorinated mixture was 700 ppm. Experi ments have shown that the dechlorination step and the temperature had great effect on the product distribution from the hydrocracking step. It was obs erved that the dechlorination step led to both degradation of PE and dechlo rination of PVC and that PE could be completely cracked with/without a cata lyst by hydrocracking even though at 673 K. The use of a catalyst decreased the gas yield and led to an increase in coke yield at 723 K. The effect of the catalyst on the boiling point range of liquid product obtained from hy drocracking depended on the reaction temperature. The chlorine compounds in dechlorinated mixture affected the catalytic activity of the catalyst espe cially at 723 K. 75% and 55% of the liquid products obtained at 723 K with and without a catalyst, respectively, were hydrocarbons having boiling poin ts ranging from 323 to 473 K. (C) 2001 Elsevier Science B.V. All rights res erved.