Researchers use PEM fuel cell reactor to convert biomass-derived acetone into isopropanol; new biomass to fuels pathway
A team from the University of Wisconsin-Madison, University of Massachusetts-Amherst and Gwangju Institute of Science and Technology of South Korea has demonstrated the feasibility of using proton-exchange-membrane (PEM) reactors electrocatalytically to reduce biomass-derived oxygenates into renewable fuels and chemicals.
George Huber, UW-Madison professor of chemical and biological engineering, and his collaborators used a PEM fuel cell reactor to reduce the model biomass compound acetone into isopropanol— a chemical compound with a wide variety of pharmaceutical and industrial applications, including as a gasoline additive—on an unsupported platinum cathode. The advance paves the way for researchers to convert biomass molecules such as glucose into hexanes, which are significant components of gasoline currently derived by refining crude oil.
A paper on their work is published in the journal ChemSusChem.
Unlike other technologies that use large quantities of hydrogen gas to convert biomass to biofuels, the team’s process is driven by electricity. To reduce biomass molecules into fuel, Huber’s team feeds water into the anode side and passes an electric current through the water to generate protons and electrons. The electrons run through a circuit and the protons pass through the proton-exchange membrane to the cathode side, where they generate hydrogen. The hydrogen reacts with the biomass molecule and reduces it to fuel, while oxygen exits the system.
The current efficiency (the ratio of current contributing to the desired chemical reaction to the overall current) and reaction rate for acetone conversion increased with increasing temperature or applied voltage for the electrocatalytic acetone/water system. The reaction rate and current efficiency went through a maximum with respect to acetone concentration. The reaction rate for acetone conversion increased with increasing temperature for the electrocatalytic acetone/hydrogen system. Increasing the applied voltage for the electrocatalytic acetone/hydrogen system decreased the current efficiency due to production of hydrogen gas.—Green et al.
Huber’s team demonstrated the biomass-to-biofuel reduction process in a continuous-flow reactor. The process yields 50% more liquid fuel over ethanol fermentation processes.
At the production level, the process also could be modular, making it potentially a scalable technology with which reactors could be close to the biomass, and run at night with less expensive electricity, says Huber.
In future work, Huber hopes to improve the catalysts and membranes in the fuel cell to make the process more efficient. While the team used acetone and a few other molecules as their proof-of-concept, one of Huber’s goals is to repeat the process with sugar.
Huber received support for the research from the University of Massachusetts Commercial Venture and Intellectual Property Technology Development Fund.
Green, S. K., Tompsett, G. A., Kim, H. J., Kim, W. B. and Huber, G. W. (2012), Electrocatalytic Reduction of Acetone in a Proton-Exchange-Membrane Reactor: A Model Reaction for the Electrocatalytic Reduction of Biomass. ChemSusChem. doi: 10.1002/cssc.201200416