!2022/03/09)

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A safe synthesis of hydrogen peroxide inspired by nature
A new homogeneous catalyst enables the safe and direct synthesis of hydrogen peroxide

Fukuoka, Japan—Hydrogen peroxide is a ubiquitous chemical found in most homes and usedin everything from dying hair to treating wounds. It is also an invaluable agent for manyindustries from food, textiles, and even in semiconductor production.
Reporting in JACS, researchers at Kyushu University have developed a new process tosynthesize this chemical utilizing a new homogeneous catalyst inspired by nature. Moreover,the process is significantly safer than conventional methods.
Scientists have been reporting the synthesis of hydrogen peroxide for more than two hundredyears. Today's industry standard is a method known as the 'anthraquinone method,' a
stepwise and indirect process that dates back to World War II. However, while hydrogen
peroxide—or H2O2—itself is relatively harmless, its production sometimes is not.
"Current synthesis methods are wasteful. This is a result of the high flammability of thehydrogen and oxygen mixtures and the requirement of varying materials," explains Professor
Seiji Ogo from Kyushu University's Faculty of Engineering, who authored the study.
Ogo and his team have been seeking a greener approach for H2O2 production, looking tonature for inspiration. They focused particularly on a set of enzymes called 'hydrogenases.'
These are enzymes found in extremophile microorganisms—organisms that live in extremely
hostile environments, like the very bottom of the ocean.
Another location of extremophile activity is the hot springs of Japan. This is where Ogo andcolleagues found hydrogenase S-77. Hydrogenases show promising properties for the transferof electrons from hydrogen to oxygen molecules, a key event for the synthesis of hydrogenperoxide.
"Hydrogenase S-77 was the source of inspiration for previous work in my lab, where weconstructed a rhodium-based homogeneous catalyst," explains Ogo. "The catalyst worked byfacilitating the withdrawal of electrons from hydrogen molecules and then donating them tooxygen molecules. However, it gave a poor yield."
In their new study, the catalyst was improved by incorporating a N-heterocyclic carbene
ligand for the reduction stage, which led to a turnover number—a reflection of the efficiencyof the reaction—more than 250 times higher that of the previous catalyst, and one of thehighest ever reported for a homogeneous catalyst.
Further, unlike the conventional anthraquinone method, the new homogeneous catalyst
requires only one step and no separation of hydrogen and oxygen gas from the reaction flask.
Therefore, with more development, the new catalyst could lead to a process that demands

less material and lower costs at industrial levels.
"The new process is an ideal reaction for hydrogen peroxide synthesis because it involves asafe reaction mixture, reaction in one vessel, and direct synthesis using only hydrogen andoxygen," concludes Ogo. "Companies are always seeking ways to lower production costs. Our
catalyst may be an important resource for many industries."###For more information about this research, see "Safe, One-Pot, Homogeneous Direct Synthesisof H2O2" Seiji Ogo, Takeshi Yatabe, Tamon Tome, Riko Takenaka, Yoshihito Shiota, and Kenji
Kato, JACS, https://doi.org/10.1021/jacs.2c13149
About Kyushu UniversityKyushu University is one of Japan's leading research-oriented institutes of higher education
since its founding in 1911. Home to around 19,000 students and 8,000 faculty and staff, Kyushu
U's world-class research centers cover a wide range of study areas and research fields, fromthe humanities and arts to engineering and medical sciences. Its multiple campuses—including
one of the largest in Japan—are located around Fukuoka City, a coastal metropolis on thesouthwestern Japanese island of Kyushu that is frequently ranked among the world's mostlivable cities and historically known as Japan's gateway to Asia. Through its Vision 2030, Kyushu
U will 'Drive Social Change with Integrative Knowledge.' Its synergistic application of knowledge
will encompass all of academia and solve issues in society while innovating new systems for abetter future.

Fig. 1. The safer production of H2O2. Inspired byhydrogenases in nature a Kyushu University researchteam has developed a new catalyst that can synthesizehydrogen peroxide, H2O2, in a safe and efficientmanner. By adding N-heterocyclic to the rhodiumbased homogeneous catalyst they developed in thepast the research team was able to increase H2O2
production 250-fold. (Ogo Lab/Kyushu University)[Contact]
Seiji Ogo, Professor
Department of Applied Chemistry, Faculty of Engineering
E-mail: ogo.seiji.872@m.kyushu-u.ac.jp