Researchers have created a novel method that leverages microwave-assisted flow reactions and reusable solid catalysts to effectively break down polysaccharides into simple sugars. This new device employs a continuous-flow hydrolysis technique, in which cellobiose is passed through a sulfonated carbon catalyst that is heated with microwaves, facilitating the efficient conversion of cellobiose into glucose.
A group of scientists at Kyushu University has pioneered a device that integrates a catalyst with microwave flow reaction technology to effectively transform complex polysaccharides into simple monosaccharides. This device uses a continuous-flow hydrolysis system, where cellobiose—a disaccharide formed by two glucose units—is directed through a sulfonated carbon catalyst, which is heated by microwaves. This chemical process successfully breaks down cellobiose into glucose. Their findings have been shared in the journal ACS Sustainable Chemistry & Engineering.
The conversion of biomass into valuable resources has been an area of research for many years. Biomass polysaccharides, which are long, complex sugar chains found abundantly in nature, are considered promising candidates for efficient conversion because they can be transformed into simple sugars. These simple sugars can then be utilized in various sectors, including food, pharmaceuticals, and chemical manufacturing.
Hydrolysis is a highly effective reaction for converting long-chain sugars into simple sugars, typically relying on acids as catalysts. While many acid catalysts exist in gas or liquid form, solid acid catalysts—which are acids in solid state—have gained attention for their recyclability and sustainability.
Nevertheless, solid acid catalysts often require high temperatures to function effectively. To address this challenge, Associate Professor Shuntaro Tsubaki from Kyushu University’s Faculty of Agriculture and his research team explored the application of microwave flow reactions to heat the solid catalysts during the hydrolysis process.
“Microwaves generate a localized high-temperature reaction zone on the solid catalyst, which enhances catalytic activity while maintaining a lower overall reaction temperature,” Tsubaki points out. “Moreover, this design allows for a continuous flow of the substrate through the reaction chamber where microwaves heat the catalyst, leading to higher yields of the resulting product.”
The device developed by the researchers features a solid acid catalyst made from sulfonated carbon. They tested the system using cellobiose, a disaccharide, as the model substrate. In their setup, a cellobiose solution flows through the sulfonated carbon catalyst, heated to temperatures between 100-140℃ using microwave energy. This process effectively breaks down cellobiose via hydrolysis, resulting in the production of glucose.
A crucial factor contributing to the system’s efficiency is the ability to distinctly separate the electric and magnetic fields produced by the microwaves.
“Microwaves generate both electric and magnetic fields. The electric field heats dipolar materials, such as water—this is similar to how microwaves heat your food. Conversely, the magnetic field heats conductive materials like metals and carbon,” explains Tsubaki. “In our device, we enhanced catalytic activity by isolating the two fields, applying the electric field to heat the liquid cellobiose solution while simultaneously using the magnetic field to raise the temperature of the catalyst.”
Microwave-enhanced catalytic reactions have been effectively employed in diverse chemical processes, including organic synthesis, plastics recycling, and biomass conversion. The research team is optimistic that as renewable energy sources grow more prevalent, electric-powered chemical production—like their method—will drive the industry toward a more sustainable future.
“We anticipate that our system will contribute to developing more sustainable methods of chemical synthesis. We also plan to investigate the application of our approach to the hydrolysis of other polysaccharides, as well as proteins for the generation of amino acids and peptides,” concludes Tsubaki.
