PLASTIC WASTES RECYCLING USING MODIFIED ZMS-5A ZEOLITE

E. David^1*, I. Stefanescu¹, V. Stanciu¹, N. Aldea², C. Sandru¹, A. Armeanu¹

¹National Research and Development Institute for Cryogenics and Isotopic Technologies - ICIT Rm. Valcea, code 240050 - Rm. Valcea, Uzinei 4, CP7 Raureni, Valcea, Romania

ABSTRACT

The huge amount of plastic waste that resulted from the dramatic increase in polymer production gives rise to serious environmental concerns, as plastic does not degrade and remains in the municipal refuse tips for decade. According to a nation-wide  survey conducted shows that thousands of tonnes of plastic waste is generated daily in our country, and only 30 wt% of the same is recycled, balance 70 wt% is not possible to dispose off. Plastic waste being more voluminous than organic waste takes up a lot of landfill space that is becoming a scare and expensive. The only sustainable solution is degradation of polymer into various smaller molecular weight fragments. Catalytic degradation of plastic waste offers considerable benefits as compared to thermal degradation and other methods used. Catalytic degradation occurs at considerably low temperature and forms hydrocarbons in the range of motor range fuel. In such degradation process, the most valuable fuel is obviously liquid fuel. Although gaseous products are useful too, as their burning can contribute to the energy demand of an endothermic polymer cracking process, excess gas production is not desirable.

This process involves catalytic degradation of waste plastic into fuel range hydrocarbon. A catalytic cracking process in which waste plastic were melted and cracked in the absence of oxygen and at  high temperature, the resulting gases were cooled by condensation and resulting crude oil was recovered. Noncondensable fraction contains hydrogen from where this can be separated and recovered. From crude oil various products petrol, diesel and kerosene etc. can be obtained by distillation. This process mainly consists of four units (1) reacting vessel or reaction chamber (2) condensation unit (3) receiving unit (4) distillation unit. More specifically the degradation of waste plastic except polyvinyl chloride (PVC) and polyethylene terephthalate (PET) over two  grade cracking catalysts, containing 2% and 8% Fe₂O₃ or Fe supported on ZMS-5A zeolite, was studied in a semi-batch reactor. Also the effect of polymer catalyst ratio was studied on the formation of hydrogen and  liquid hydrocarbons. The best results were obtained when polymer catalyst ratio was 4:1 and after this ratio the liquid yield decreases. Furthermore alternate method for disposal of waste plastic is also studied. And the results of this process are found to be better than other alternate methods which are used for the disposal of waste plastic.

KEYWORDS: fuel compounds, catalytic degradation, plastic waste