Production of hydrogen rich products from mixture of polyolefin and PET over different modified ZSM-5 catalysts

Abstract

The goal of this work was the production of hydrogen rich fraction and high value added products by pyrolysis of waste plastics over zeolite catalysts. The effects of Si/Al ratios: 22.5, 49.1 and 65.5 on product yields were also investigated. Raw materials (polyolefin) and polyethylene terephthalate (PET)) were placed in a horizontal tubular furnace. For pyrolysis, high temperature and nitrogen flow was used. It was found, that the transition metal incorporated into the structure of synthetic zeolite had an advanced effect to the hydrogen yield and isomerization. Acidic catalysts with high Si/Al ratio can also support the decomposition of C-C bonds, maximize the yields of gaseous products and minimize the amount of pyrolysis oil. The maximum hydrogen production (47.0 %) was achieved over Ni/ZSM-5 catalyst. This was happened due to the presence of nickel in the catalyst which increasing the conversion rate. Pyrolysis oil contains high content of aromatic compounds, which was caused by the structure of PET waste and isomerization effect of ZSM-5 catalyst. For hydrogen both the aromatization reactions and the high concentration of unsaturated branched compounds could be blamed. Keywords: pyrolysis, PET, polyolefin, hydrogen, metal loaded catalysts, transition metal