Comparison of plastic types for catalytic degradation of waste plastics into liquid product with spent FCC catalyst

The catalytic degradation of waste plastics such as polyethylene (HDPE, LDPE), polypropylene (PP) and polystyrene (PS) over spent fluid catalytic cracking (FCC) catalyst was carried out at atmospheric pressure with a stirred semi-batch operation at 400 degreesC using the same reaction temperature programming. The objective was to investigate the influence of plastic types on the yield, liquid product rate and liquid product distribution for catalytic degradation. The catalytic degradation of waste PE and PP with polyolefinic structure exhibited the liquid yield of 80-85% and the solid yield of below 1%, whereas that of waste PS with polycyclic structure produced much more liquid, solid products and much less gas products. Accumulative liquid product weight by catalytic degradation strongly depended on the degradation temperature of the plastics. Among the polyolefinic polymers, both waste HDPE and PP showed around 80% of olefin components in the liquid product while waste LDPE favored more paraffin and aromatic formation, but all polyolefinic samples had a very similar tendency for the molecular weight distributions of liquid product. On the other hand, for waste PS the liquid products showed the aromatic of 97% or over and the C-8 aromatic components of about 75%. (C) 2002 Elsevier Science Ltd. All rights reserved.