High quality liquid fuel production from waste plastics via two-step cracking route in a bottom-up approach using bi-functional Fe/HZSM-5 catalyst.

Abstract

Plastic waste is a serious menace to the world due to its fastest growth rate of~5% per annum and requires efficient technologies for its safe disposal. Plastic liquefaction producing liquid hydrocarbons is an effective way to dispose waste plastics in an eco-friendly manner. In present study, high quality liquid fuel is produced from waste plastics via two-step bottom-up cracking approach. A comparative analysis of liquid products obtained in thermal and catalytic cracking performed at relatively lower temperature (350°C) with minimal catalyst to plastic feed ratio (1:30) has been studied. Catalytic cracking via two-step bottom-up route provides higher fraction of fuel range hydrocarbons in comparison to the thermal cracking. Catalytic cracking is performed using two different catalysts; HZSM-5 and 5%Fe/HZSM-5 in which later results in higher liquid yield (76wt%) than former (60wt%) having comparable fuel characteristics. GC-MS results confirm that liquid product obtained via catalytic cracking contains higher fraction of fuel range hydrocarbons (C6-C20); 66.39% for 5%Fe/HZSM-5 and 47.33% for HZSM-5 which is comparatively higher than that obtained in thermal cracking (27.39%). FT-IR, 1H and 13C NMR spectroscopic studies confirm that liquid hydrocarbons obtained via catalytic cracking have comparable chemical characteristics with fuel range hydrocarbons. Physiochemical properties of catalysts are studied using XRD, XPS, BET, FE-SEM, HR-TEM, NH3-TPD and H2-TPR techniques and correlated with activity results. Analysis of commercial diesel fuel is also incorporated to compare the fuel characteristics of liquid products.