My field of research falls within the framework of green chemistry and engineering. More specifically, it involves the development of intensification strategies in the subcritical water (subH₂O) treatment of biomass into biofuels and platform chemicals. These intensification strategies include the use of carbon-based materials as catalysts, microwave irradiation as a heating mechanism, supercritical carbon dioxide (scCO₂) as a solvent, and reactive separation as a mode of operation.

Biomass has been used primarily in my research because it possesses hydrocarbon chains in its structure similar to fossil fuels, albeit in different proportions of carbon and hydrogen, as well as oxygen. Therefore, it can undergo the same transformations as those of crude oil, for example, in order to produce fuels, plastics, and specialty chemicals. To accomplish these transformations, we have employed hydrothermal treatment as the core technology. In one study, we performed the conversion of glucose to 5-hydroxymethylfurfural (HMF), which is a highly versatile platform chemical in the production of fuels and plastics. The process involved the addition of supercritical carbon dioxide to provide the catalyst in the system in the form of carbonic acid. This acid was formed from the reaction between water and scCO₂, which has significantly higher solubility in aqueous solutions than atmospheric CO₂.

Aside from the addition of scCO₂, HMF production was also performed under reactive separation. In this setup, a scCO₂ was made to continuously flow through a stagnant aqueous glucose solution. Our results showed that the reactive separation allowed for a simultaneous and highly selective extraction of HMF owing to the enhanced solubility of HMF in CO₂ at supercritical conditions. The raw material and side products, which were polar compounds such as glucose, fructose, levulinic acid, and formic acid, were retained in the aqueous solution.

In another study, we used graphene oxide (GO) under microwave irradiation in the depolymerization of fucoidan to fucoidan, which are the marine-based equivalent of cellulose and glucose, respectively. As a carbon-based catalyst, GO can also be derived from biomass. In the depolymerization of fucoidan, an acid catalyst is required to effectively cleave the glycosidic bonds in its structure to recover fucose. This was accomplished in our system via two mechanisms: (1) By taking advantage of the microwave absorptivity of GO, local heating on its surface supplied the necessary heat to initiate random scission in fucoidan. (2) Then the oxygen functionalities on the surface of GO, which were acidic in nature, generated the necessary catalysts in the form of hydronium ions to target the glycosidic oxygen in fucoidan and break its bond, thus producing fucose.

These studies were not only conducted from an experimental point of view, but from a theoretical perspective as well. In particular, semi-empirical quantum calculations were performed to show how glucose can be converted to 5-HMF by the Brønsted acids and bases present in the subH₂O–scCO₂ system. Furthermore, from DFT calculations, isopropanol was shown to facilitate hydride shifts, which are predominant in the glucose isomerization and fructose dehydration steps of HMF production, thus reducing the activation energy of the reaction. Lastly, semi-empirical quantum calculations were also performed to generate the reaction pathway for the acid-catalyzed depolymerization of fucoidan to fucose.

Research Activities

[Oral presentation in a workshop]
YL Kam, JKCN Agutaya (presenter), AT Quitain, Y Ogasawara, M Sasaki, MK Lam, S Yuzup, S Assambumrungrat, T Kida. Graphene Oxide under Microwave Irradiation as an Effective Catalyst in the Production of Biodiesel from Chlorella vulgaris. e-ASIA Workshop and Site Visit.
2023 March 15–17. Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia (online).

8th JASTIP-WP2 Annual Workshop.
2023 January 9. CO113, TSP, NSTDA, Thailand (online).

[Participation of Internship]
Block course titled “Chemical Sensors – Basics, Technology and Applications” hosted by the Weimar Research Group.
2023 March 6–17. Institute of Physical and Theoretical Chemistry, University of Tübingen, Germany

 
Discussion of the theory behind Kelvin probe measurements

Demonstration on the use of the Kelvin probe

[Conference organizer]
3^rd International Symposium on Green Chemistry and Engineering as part of the Sakura Science Program hosted by the Kida Laboratory.
2023 January 18. Kumamoto University, Japan.

[Poster presentation in a conference]
 JKCN Agutaya (presenter), T Shinkai, Y Inomata, AT Quitain, T Kida. Theoretical study of the formation of hydroxyl groups on Pt-doped ZnO(10-10) from the heterolysis of water. 48th International Congress on Science, Technology and Technology-based Innovation (STT 48).
2022 November 29 – December 1. Walailak University, Thailand

 
Poster at the SST 48 conference in Thailand              Awarding ceremony at the 48^th STT

[Co-authorship of a paper]
Nishizono, M.; Soreli, C.; Issasi, C.; Agutaya, J. K. C. N.; Sasaki, M.; Mizukami, H. “Production of Dried Tomato Powder with a High Concentration of Functional Components and Nutrients.” Journal of Antioxidant Activity 2023, 2(4), 1–21.
* Performed at Dr. Agutaya's previous affiliation

[Laboratory Visit]
Visit to the Ohgaki Laboratory, Katahira Laboratory, and Watanabe Laboratory of Kyoto University.
2022 September 26. Kyoto University, Japan.
  *This visit to Kyoto University was upon the invitation of Prof. Hideaki Ohgaki as part of the e-ASIA Joint Research Program of Prof. Kida and Prof. Quitain.

    
Tour of the Katahira Laboratory, Kyoto University

Presentation of and discussion with Prof. Takashi Watanabe about the results of his e-ASIA project on biorefinery