PYROLYSIS OF POLYOLEFINS WITH STEAM TO YIELD OLEFINS

The polyolefinic fraction of post consumer plastics waste was pyrolyze d in a fluidized bed lab scale reactor. In order to improve olefin yie lds, steam was used as the fluidizing agent. The influence of the reac tion temperature on olefin yields was investigated in the range 600-80 0 degrees C. Furthermore, the residence time was varied at a given tem perature of 700 degrees C between 1.8 and 3.2 s. The product distribut ion shows a characteristic influence of the cracking temperature on th e yields of the different components. High amounts of olefins are obta ined at temperatures around 700 degrees C, with 20-31 wt.% ethene, 14- 18 wt.% propene, 3-6 wt.% butenes and, additionally, 19-23 wt.% pyroly sis gasoline as the main products. These yields are similar to the pro duct distribution of naphtha cracked in a steam cracker, with 29 wt.% ethene, 16 wt.% propene, 10 wt.% butene/butadiene, and 24 wt.% pyrolys is gasoline. After separation the olefins can be reused as monomers fo r the production of polyolefins.