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Performance of TPA loaded sba-15 catalyst in polypropylene degradation reaction

Ersoy Yalçın, Ulviy
Plastic materials are widely used due to their low cost and easy processing properties. With an increase in plastic usage, the amount of plastic wastes has also increased, and this situation causes environmental problems. Landfilling, incineration, and recycling are the methods used for the disposal of plastic wastes. Landfilling is not a convenient method as it causes soil pollution. Incineration is also not preferred due to its harmful effects on the environment caused by toxic gases. Recycling seems to be the most convenient method to eliminate environmental problems. In this study, tungstophosphoric acid (TPA) loaded SBA-15 catalysts with different TPA loadings were synthesized via one-pot hydrothermal method. To investigate the performance of these catalysts in the degradation of PP, pyrolysis experiments were carried out at 315 °C and 400 °C for 30 minutes, with a heating rate of 5°C/min, under nitrogen atmosphere at a flow rate of 60 cc/min and a catalyst to polymer weight ratio of 1/2. Characterization of the synthesized materials was done using various characterization methods. Synthesized materials exhibited Type IV isotherms, and pore sizes changed between 6.7-9.7 nm, showing the mesoporosity of the materials. Surface areas of the synthesized materials decreased with an increase in the amount of TPA loaded. All catalysts exhibited both Lewis and Brønsted acid sites. TPA loaded SBA-15 catalysts decreased the activation energy of PP degradation reaction from 172 kJ/mol to 100.5 kJ/mol. The liquid product amount increased with an increase in the reaction temperature and TPA loading while the gas product amount decreased. The solid residue was not observed when the catalysts were used. TPA loaded SBA-15 catalysts had high isobutane and ethylene selectivity among gas products. The majority of the liquid products consisted of C8-C14 at both temperatures. SBA15-TPA 0.20 showed the best performance in the catalytic degradation of PP with the highest selectivity of C10 at 315°C and C14 at 400 °C. Products in the gasoline range can be obtained mostly at 315 °C, while products in the diesel range can be obtained mostly at 400 °C.