Chemical catalysed recycling of polypropylene over a spent FCC catalyst and various commercial cracking catalysts using TGA

Thermogravimetric analysis (TGA) has been used as a tool to characterise the activity, regenerability and deactivation behaviour of spent FCC commercial catalyst (FCC-s1) in the degradation of polypropylene. The FCC-s1 catalysts and amorphous silica–alumina (SAHA) significantly reduced the activation energy as compared with thermal process, and zeolites (ZSM-5 and HUSY) further reduced the activation energy. However, silicalite catalysts gave very minimal effect on PP degradation at a temperature similar to that of thermal cracking. Analysis of the TGA results allowed a relationship between catalyst activity and coke content to be derived. The activity of FCC-s1 catalysts was found to fall exponentially with coke content, and it could be recover most its initial value. The results represent an interesting alternative to have significant impact on the economics of a catalytic polymer degradation process employing post-use FCC commercial catalysts of zero market value.