Research Results

Establishing a new method of transforming plastics!
~Succeeded in developing a solid catalyst system effective for the synthesis of useful chemicals from polyolefin plastics at low temperatures~

This research presentation was introduced in the following media.

• January 14, 2021 The Chemical Daily
• February 8, 2021 The Chemical Daily

Key points of this study

• We have succeeded in developing a solid catalyst that converts polyolefin-based plastics into useful chemicals such as lubricants under low-temperature conditions.
• It is expected to be a new solid catalytic technology for plastic conversion.

Summary

 Associate Professor Masazumi Tamura (Research Center for Artificial Photosynthesis, Osaka City University), and Professor Keiichi Tomishige (Department of Applied Chemistry, Graduate School of Engineering, Tohoku University), have succeeded in developing a solid catalyst system that is effective in decomposing polyolefin-based plastics, which account for the majority of plastic waste, and have shown that lubricating oils and liquid chemicals, which are useful chemicals, can be synthesized at high yields under low-temperature conditions.

 Technologies such as oil conversion and gasification are known as chemical recycling technologies for polyolefin plastics, but they have various problems, and there has been a need to establish a technology to convert plastics under low temperature conditions and a catalyst technology that enables direct and selective conversion into beneficial chemical raw materials. The Cerium oxide-supported ruthenium catalyst (Ru/CeO₂ catalyst) developed in this research has succeeded in lowering the reaction temperature by more than 100°C compared to conventional technology, and can be applied to commercially available garbage bags and waste plastics, making it the world's first solid catalyst system that has succeeded in obtaining useful chemicals with high yields.

 The results of this research were published online in Applied Catalysis B: Environmental (IF=16.68) on Thursday, December 10, 2020.

Research Background

 In recent years, plastic waste has become a global problem, such as marine debris and its impact on biological systems. Against this backdrop, there is a need to reduce the amount of plastic used and establish appropriate disposal methods, and plastic recycling and reuse technologies are becoming important from the perspective of resource recycling. Polyolefin-based plastics account for the majority of plastic waste, and there is an urgent need to develop technology to recycle them. Among recycling technologies, chemical recycling is expected to be a process that enables low-carbon processes, waste reduction, and the supply of raw materials and chemicals. Chemical recycling technologies for polyolefin-based plastics such as oil conversion and gasification are known, but they generally require high temperatures of 400°C or more, and have problems such as cheap gas production, large amounts of by-products, and catalyst deactivation. From the viewpoint of improving energy use efficiency and reducing carbon dioxide emissions, there was a need to establish a technology that enables the conversion of plastics under low-temperature conditions, as well as a catalyst technology that enables direct and selective conversion of high-value-added chemical raw materials as products.

Outline of Research

 As a result of catalyst development using polyethylene as a model substrate, it was found that Cerium oxide-supported ruthenium catalyst (Ru/CeO2 catalyst) exhibited higher activity than other metal-supported catalysts. As a result, it has become possible to convert polyolefins under conditions as low as 200°C and low hydrogen pressure conditions such as 2 MPa, and it has also been clarified that useful chemicals such as lubricants and liquid chemicals can be obtained with high yields of 90% or more. Compared to the previously reported solid catalysts, this catalyst is capable of lowering the reaction temperature required for the decomposition of polyolefin-based plastics by more than 100°C, making it an extremely active solid catalyst. In addition, this solid catalyst system can be applied to commercially available garbage bags and waste plastics, and we have been able to obtain useful chemicals with high yields.

Expected effect

 This technology enables the resource recycling cycle of plastics and is expected to contribute to solving the problem of plastic waste. In addition, by replacing chemical processes synthesized from petrochemical resources, carbon dioxide, energy, and costs will be reduced, and it is expected to lead to the creation of a low-carbon society.

Future Developments

 For practical use, we will develop a catalyst process using actual waste plastics.

Financial Information

 This research was supported by the Environmental Research Promotion Fund (JPMEERF20183R03) of the Environmental Restoration and Conservation Agency.

Publication Information

All Press Release (PDF:1069KB)

Article source: Osaka City University website