Xiong Peng¹, Travis J. Omasta², William E. Mustain¹

¹ College of Engineering and Computing, University of South Carolina, Columbia, SC 29208, United States

² Department of Chemical and Biomolecular Engineering, University of Connecticut, United States

Biomass resources prove an ideal alternate to fossil resources and function as the only sustainable source of organic compounds [1]. Today, biomass energy provides approximately 10% of the global total energy needs [2], and plays an important role in contributing to the world’s economy. Thermochemical methods to convert biomass such as gasification, pyrolysis and combustion have been widely used to convert biomass into chemicals and fuels [3]. However, thermochemical conversion methods are notorious for high capital cost, intensive energy consumption and negative environmental impacts [4]. Biological routes like anaerobic digestion for biomass conversion to fermentation products, ethanol and acetic acid, has received great research attention due to its reduced environment footprint and significantly lower energy consumption [5]. However, additional processing steps are needed to be developed in order to convert these liquid products to fuels with a high carbon efficiency and low environment footprint. Electrochemical approaches are ideal in both bases, as they allow for facile pairing with renewable energy and operate at low temperature and pressure.

From a chemical processing perspective, acetic acid has not historically been a very attractive product – and nearly all of the biologically-derived acetic acid is sold as vinegar for food. However, biologically-inspired engineered systems that enable the efficient digestion and processing of lignocellulosic biomass may make acetic acid widely available in the near future and it will be imperative that catalytic pathways are established to convert this need feedstock into useful commodity chemicals and/or fuels. In this work, our team developed a two compartment three-electrode operando cell to study the acetate oxidation reaction mechanism. Pt was used as both working and counter electrode, and Ag/AgCl was the reference electrode. The cell was designed to have a large electrode surface area with small electrolyte volume. There were 12 products of acetate partial oxidation detected in this work. Nine of these twelve products have been reported before: ethylene, ethane, methane, methanol, methyl acetate, carbon dioxide, carbon monoxide, oxygen, hydrogen [6]. The three remaining products: formate, methyl formate, and formaldehyde have not been reported before to the best of our knowledge. By analyzing all of the products against potential, we propose a new complex reaction pathway that is able to account for the production of all the products detected in this study.

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