Valorization of polypropylene pyrolysis waxes by catalytic cracking on hybrid catalysts

Plastic recycling has become necessary, in terms of plastic waste recovery, and as a source of hydrocarbons for different petrochemical activities. In the pyrolysis of polyolefins, waxes are obtained at low temperature, which minimizes energy requirements and the waxes are readily integrated in the refinery. The valorization of propylene pyrolysis waxes was evaluated by using them as additives to the usual FCC feedstock (VGO). Experiments with reaction times and catalyst/oil ratio similar to industrial unit conditions were conducted in a riser simulator reactor, using both commercial FCC catalysts based on HY zeolites and hybrid catalysts made up of a mixture of HY and HZSM-5 zeolites. The addition of waxes had a positive impact in terms of quality and quantity of the obtained products, with high temperatures and reaction times being the most suitable for achieving the highest conversion and octane number. Concerning gasoline composition, low temperatures and high reaction times produced an isoparaffinic gasoline, while high temperatures and low reaction times enhanced olefins in gasoline. The hybrid catalyst decreased the aromaticity of the gasoline, producing more gasoline range olefins and high molecular weight isoparaffins. This is an abstract of a paper presented at the 7th World Congress of Chemical Engineering (Glasgow, Scotland 7/10-14/2005).