Pyrolysis of waste plastics with microwave and thermal methods

Plastics obtained by the polymerization of hydrocarbons are produced more than 400 million tons each year to meet the demands of the modern world. Plastics are important materials that are durable, strong, inexpensive and with many other features. Due to these properties, the use of plastic is increasing day by day. But, plastics are important in terms of environmental pollution since they can remain in nature for a long time without degradation. On the other hand, the continuous increase in urbanization and industrialization caused a significant increase in energy demand. Nowadays, there is a need to search alternative energy sources in addition to traditional energy sources to meet this demand. The transformation of waste plastics into alternative energy sources by appropriate methods is important both for environmental pollution and for obtaining alternative fuel. In this study, the conversion of waste plastic to a new liquid fuel by polyethylene terephthalate (PET) pyrolysis method was investigated. Pyrolysis experiments were performed in a batch reactor under catalytic and non-catalytic conditions, reaction time of 15-90 minutes, reaction temperature of 325-425 °C, solid/solvent ratio of 1/4 and initial nitrogen gas of 20 bar. The waste plastic samples were used as raw and pre-treated in the microwave. The pyrolysis studies showed that the pyrolysis of received and microwave pre-treated samples in catalytic and non-catalytic conditions gave the appropriate processes parameters: at temperature of 375-400 °C and reaction time of 30 minutes. It was determined that the pre-treatment time in the microwave had a partial effect on the liquefaction products. As a result of the pyrolysis at the optimum values in the catalytic conditions of the pre-treated in microwaves sample, the total conversion was 62,4 % and the oil+gas yield was 38,7 %. According to the results of GC- MS analysis, the obtained oils consist of mainly single and multi-ring aromatic compounds and polyaromatic compounds.