Plastic Waste (PW) has become a major global challenge. Since the plastics industry began, the cumulative production of plastic has reached 9.200 million tons worldwide, with further increases expected in the coming decades. Of this amount, 5.000 million tones ended up as waste. Chemical recycling (CR) is an emerging theme in PW management, which has the potential to contribute to a low carbon, resource efficient and sustainable economy. As a form of CR, hydrocracking (HDC) stands as one of the most promising technologies to convert PW into a petrochemical feedstock. This can be next converted by the Steam Cracker (SC) process into ethylene and propylene monomers to produce new plastics, provided SC feedstock specifications are obeyed (C4-C12 hydrocarbons, no olefins, naphthenes &lt; 16,4 %, aromatics &lt;4.8 %). This work fits into this perspective of a CE for plastics and aims to evaluate the potential of the parent and metal (Ni, Pt) based H-USY to convert HDPE into circular carbon feedstocks. The influence of catalyst and metal nature of process conversion and product distribution was analyzed in this study. The possibility to reuse the metal-based systems for more than one HDC cycle was also studied. The results have shown that parent H-USY zeolite allows for a complete conversion of HDPE at T=390C, t=60 min and PH2i20 bar. Instead, upon the incorporation of a Ni or Pt metallic source it is possible to reach higher conversions (85% and 100%, respectively) at significant milder conditions (260 C, 15 min, 20 bar). Moreover, Pt based H-USY Zeolite also allows for an adequate hydrocarbons’ distribution, mostly in C2-C10 range hydrocarbons (&gt; 90 wt.%), without olefins and exhibiting a low content of naphthenes (&lt;10.8%) and aromatics (&lt;4.8%), meeting the specifications required for SC feedstocks. In addition, both Ni and Pt based zeolites proved to be a stable and robust catalyst for more than one HDC cycle, allowing for similar conversions and product distributions to the fresh systems.

HDPE hydrocracking over parent and metal-based HUSY zeolites: A route for a circular economy

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.