Utilization of Nanobubbles for the Heterogeneously Catalyzed Hydrogenation of 2-Ethyl-9,10-anthraquinone

• Applicant: Dr.-Ing. Kristin Hecht, since 6/2024
• Subject Area: Chemical and Thermal Process Engineering
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441298178

Nanobubbles are defined according to ISO 20480-1:2017 as bubbles with a diameter of less than 1000 nm. The properties of nanobubbles have been investigated scientifically since many years, especially in water and aqueous solutions and in a few cases in other liquid media. Meanwhile, nanobubble generators have become commercially available and nanobubble suspensions find use in various technical applications in the fields of agriculture, health and nutrition.The small diameters of nanobubbles result in a high internal pressure of the bubble, a large specific gas-liquid interfacial area, as well as a very low rise velocity. Due to these properties, nanobubbles should also be interesting for use in chemical processes. The evidence that nanobubble suspensions could be used successfully for chemical reactions has only been shown in a few examples by the working group of N. Mase in Japan. These examples—the hydrogenation of C-C double bonds, the hydrogenation of nitrogen groups, and the oxidation of aldehydes to alcohols—show a significant increase in the rate of the chemical reaction through the use of nanobubble suspensions.The hydrogenation of an alkyl-anthraquinone is an important step in the anthraquinone process, an economically important process for the production of hydrogen peroxide from hydrogen and oxygen. In the framework of the proposed work, the hydrogenation of 2-ethyl-9,10-anthraquinone will be carried out using hydrogen nanobubble suspensions and compared to the dosing of gas through a tube as a model of a classical method for the dosing of the gas. Due to the characteristic properties of nanobubbles, a significantly faster rate of reaction is expected compared to the introduction of gas through a tube. The anthraquinone process is often carried out industrially in mixtures of alcohols and methyl substituted benzenes. To provide a maximal gas concentration in the reaction medium, the lifetime of nanobubbles will be determined in mixtures of alcohols and methyl substituted benzenes as well as in the pure components at different temperatures. To achieve the highest concentration of gas in the reaction medium, an artificial neural network will be use to investigate the relationships between the characteristics and parameters related to the materials and process and their influence on the bubble size distribution and concentration. If a significant increase in the rate of reaction can be achieved by dosing the gas using nanobubble suspensions, the dosing of hydrogen gas could be performed industrially at lower process pressures, resulting in advantages with respect to cost and safety.

• DFG Programme: Research Grants
• Major Instrumentation: Anlage zur Hydrierung mit kleinsten Blasen ; Nanoparticle Tracking Analysator
• Instrumentation Group: 1040 Dispergierer, Zerstäuber, Homogenisatoren ; 1950 Partikelzählgeräte und -klassiergeräte (optisch, elektronisch, außer 35
• Co-Investigator: Dr. Klas Meyer