Catalytic pyrolysis of polypropylene waste films into valuable upstream petrochemical products

Abstract

Plastic bags are greatly involved in modern Thai lifestyle, especially in food and goods packaging, creating environmental concerns on waste treatment due to their low biodegrability. A large number of plastic bags with other municipal wastes are landfilled and burned into atmosphere. Pyrolysis of these plastics is an alternative for utilizing plastic waste because it can produce valuable raw materials that can be used in petroleum and petrochemical industries. Due to high energy consumption, catalysts are also employed in plastic pyrolysis to reduce costs of operation. In this study, reprocessing effect on product distribution was studied on thermal pyrolysis of polypropylene (PP) films. Film reprocessing affected pyrolyzed products due to the changes of the rheological and some thermal properties of the films. Moreover, pyrolysis of PP films differed from that in the pellet form. Hence, forms of the PP-based materials must be considered because they had an effect on pyrolyzed product distribution and composition. In catalytic pyrolysis, sulfated zirconia was employed as a catalyst. The result showed that the cracking activity increased with the catalyst to polymer ratio and the amount of sulfate loading. Liquid product was the most dominant pyrolyzed product. Moreover, the addition of catalysts resulted in gasoline production.