Cracking catalysts used as fluidized bed material in the Hamburg pyrolysis process

Abstract

The effects of fluid catalytic cracking (FCC) catalysts as fluidized bed material on the pyrolysis of polystyrene and polyethylene were investigated at temperatures between 370 and 515°C in a scale of ∼1 kgh−1. The results were compared qualitatively with pyrolysis-GC-MS-experiments (200 μg). The catalytic influence on the product distribution is easily seen by the comparison to non-catalytic experiments with simple quartz sand. In the catalytic polystyrene pyrolysis, the product distribution is changed from the usual main product styrene (61 wt.%) to basic chemicals (18–26 wt.% ethylbenzene, 9–22 wt.% benzene, 1–7 wt.% styrene, 3–5 % toluene) and soot (15–23 wt.%). Surprisingly, it was shown that in the catalytic pyrolysis of polyethylene even at low temperatures (450–515°C) gases (48–52 wt.%) and low boiling aliphatic oils (38–39 wt.%) were received instead of waxes (∼90 wt.%) in non-catalytic experiments. A further success of the catalytic pyrolysis is a dramatic reduction of the process temperature. Pyrolysis-GC-MS-experiments confirmed these results qualitatively.