Kirin Holdings Company – Started joint research on PET, degrading enzymes for sustainable recycling
With the strong awareness of sustainability around the world, the recycling of PET plastic in particular has gained attention, as many kinds of products containing PET can be found very easily in our daily lives. In particular, there is a shared urgency regarding the creation of a sustainable PET recycling system in which container and packaging resources are recycled. Consequently, interest has grown in chemical recycling technology as a solution to this problem.
In chemical recycling, waste PET bottles are sorted, crushed and washed to remove dirt and foreign substances, then subjected to chemical decomposition to break them down and refine them into raw materials, which are then synthesized back into PET. . Currently, in the chemical recycling technology decomposition process, metal catalysts are used, and the heat treatment is carried out at high temperatures of about 300 degrees Celsius. On the other hand, the enzymatic decomposition method is attracting attention as a new recycling process, which uses enzymes instead of metals as catalysts in the degradation process.
The enzymatic degradation method
The enzymatic degradation method involves using heat-resistant PET degrading enzymes to break down PET to the molecular level of monomer. This means that PET plastic can be broken down into microscopic pieces, allowing for purer recycled PET plastic (because it is much easier to separate foreign substances from the plastic). Additionally, by using enzymes as catalysts, the decomposition process can be carried out at relatively low temperatures around 70 degrees Celsius, reducing the environmental impact at the same time.
Although there are several enzymes capable of degrading PET – one of the most commonly used plastics in the world – only a few of them have been put into practice because enzymes have a low heat tolerance and a low degradation activity under high temperature conditions. In this joint research, the objective is to obtain a thermostable PET degradation enzyme with improved heat tolerance and degradation activity by modifying PET2 – one of the thermostable PET degradation enzymes – by combining the knowledge and technologies held by the three parties.
Moreover, based on the mechanism of PET degradation activity revealed by X-ray crystallography and single molecule observation,
The development of PET degrading enzymes with high thermal stability and degrading activity will reduce the amount of enzymes required for PET degradation, thereby reducing the cost of PET recycling. The enzymatic degradation method can also reduce the thermal energy needed to degrade PET under mild conditions, thereby reducing environmental impact.
Before that, the
As part of the Kirin Group Vision 2027 (KV 2027), a long-term management plan launched in 2019, the