Background/Objectives
Historically, the chemical industry has relied on driving their processes using heat derived from the combustion of fossil fuels, resulting in significant CO2 emissions. As the electricity grid becomes decarbonized, significant opportunities exist to drive chemical processes with electricity rather than heat, eliminating the emissions from combustion heating. Electrochemical reactions are a way to directly utilize the renewable electricity, promoting the transition to electrically-driven systems. The transition to electrochemical reactions also gives an opportunity to re-examine feedstocks and process flows. For example, electrochemical conversion of biomass-derived species at distributed biorefineries becomes more viable. Before electrochemical reactions can become fully realized, the influence of reaction parameters, kinetics and mechanisms need to be understood. The electrochemical hydrogenation and hydrogenolysis (ECH) of furfural to fuels and fine chemicals will be utilized as an example for how reaction conditions have a significant impact on the decarbonization feasibility. The reaction parameters also influence reaction performance and the mechanisms and kinetics.
Approach/Activities
An experimental study was completed in the laboratory to evaluate the influence of reaction parameters on electrochemical reaction performance and kinetics. The experimental electrochemical findings were compared to classic thermochemical methods used to reduce furfural in terms of the carbon footprint.
Results/Lessons Learned
Utilizing copper electrocatalysts, the chemical intermediate furfuryl alcohol and the fuel candidate 2-methyl furan can be synthesized by electroreduction of furfural. The pH of the electrolyte significantly impacts the product selectivity and the impact of homogeneous side reactions. The reaction mechanisms and kinetics were developed utilizing initial rate studies. These rates were combined with side reaction kinetics to better understand the implications of reaction conditions. While the electrochemical reaction itself may have a lower carbon footprint than the traditional thermochemical reaction, the separation needs are what determine if an electrochemical or thermochemical reaction has a lower carbon footprint. Electrochemical production of 2-methyl furan, which can be separated out during reaction, has a lower carbon footprint compared to the thermochemical process, whereas electrochemical production of furfuryl alcohol, which requires downstream separation from an aqueous stream, is not competitive on a carbon basis with the thermochemical production method.