Latest Trends and Challenges in Feedstock Recycling of Polyolefinic Plastics
Journal of the Japan Petroleum Institute
Plastics are widely used in our daily life owing to being light, inexpensive, having good processability, and having ease of functionalization by combining additives. Global plastic production has increased from 1.5 million tons (Mt) in 1950 to 359 Mt in 2018. Over the last ten years (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018), plastic production has increased by 1.5 times 1),2) . Almost half of the global plastic is produced in Asian countries such as China (30 %), Japan
... (4 %), and other Asian countries (17 %), and in North American Free Trade Agreement (NAFTA) countries (18 %), Europe (17 %), followed by other countries (14 %) 2) . The packaging sector accounted for 36 % of global plastic demand in 2015 3) , which was the biggest segment, and which was a common tendency in EU (39.9 %) 2) and Japan (41 %) 4) . The constant growth of waste plastic generation is observed in global primary plastics waste generation data ( Fig. 1 ) 5) . According to the report from the Ellen Macarthur Foundation, 78 Mt of plastic packaging materials was produced in 2013, of which 40 % was treated by landfilling, 32 % was leaked into the environment, 14 % was incinerated for energy recovery, and only 14 % was recycled 6) . Domestically, 8.9 Mt of waste plastics were generated in 2018, of which 84 % (mechanical: 23 %; feedstock: 4 %; energy recovery: 57 %) was recycled or utilized as an energy source and 16 % was treated by incineration without energy recovery and landfill (Fig. 2) 4) . Behind the recent rapid growth in the demand for plastic recycling, there are global trends such as Sustainable Development Goals (SDGs) 7) and circular economy 8) . In addition, recent focus on ocean plastics pollution 9) 14) and the decision by China to ban waste plastics import 15) have caused significant impacts on several industrial sectors around the world. The SDGs, including 17 goals and 169 targets, aim to tackle poverty, health, and environmental conservation issues and achieve a better and more sustainable world by 2030 7) . Recent focus on ocean plastics pollution, and the decision to ban waste plastic import by China have significantly impacted several industrial sectors around the world. Yet, the global waste plastic generation is steadily growing, which has driven substantial and rapid growth in worlds' plastics recycling capacity to meet the needs for sustainable plastics use. In Japan, the Resource Circulation Strategy for Plastics was formulated in May 2019. One of the highlights of this Strategy was the milestones established: 25 % reduction of single-use plastics by 2030, 60 % reuse/recycling of plastic containers and packaging by 2030, complete waste plastic utilization through reuse and recycling by 2035, and introduction of 2 Mt of bio-based plastics by 2030. Thus, immediate and substantial promotion of research and development of technologies for plastic waste recycling and creation of social and legislative frameworks for accelerating plastic recycling are in high demand. To enable substantial enhancement in the world's recycling capacity, we believe that feedstock recycling via pyrolysis technologies is of considerable importance. Thus, this review firstly summarizes global trends in waste plastics recycling and examines the trends and challenges regarding pyrolysis technologies, such as reactor design and effective catalytic pyrolysis, toward chemical feedstock recovery from polyolefinic plastics. The authors' current project on feedstock recycling, i.e., development of pyrolysis technologies using existing petroleum refinery processes, is introduced, and the potential sources of waste polyolefinic plastics, based on material flow analysis, are discussed.