DOE OSTI2019
The conversion of CO 2 to value-added products is an attractive approach for reducing the cost of CO 2 capture. Formic acid (FA) is a multipurpose industrial chemical feedstock for formic acid fuel cells, additives in the textile and agricultural sectors, cleaning products, and corrosion inhibitors. FA can be produced directly from CO 2 via a two-electron process facilitated with DC electricity supplied via renewable/intermittent power sources [1]. The state-of-the-art method for industrial FA production is the Kemira process, which uses methanol, sodium methoxide, and CO to produce methyl formate that is subsequently hydrolyzed to formic acid. Conversely, an electrochemical approach reduces the number of chemical input for FA production, but conventional electrochemical processes for CO 2 reduction to FA continue to suffer from selectivity issues where the electrocatalyst produces a wide range of products. These competing products include FA, hydrogen, carbon monoxide, methanol, and methane that reduce faradaic efficiency by up to 50% [2]. The CAER-Andora process features an enzymatic catalyst with high selectivity for FA production with turn-over-frequency >85 s-1. The CAER-Andora process combines an electrochemical cell that features graphite electrodes and an electrochemically facile charge mediator, combined with an immobilized proprietary catalyst inside a FA production cell. These processes work together to 1) reduce faradaic inefficiencies by producing only FA, 2) protect the valuable catalyst from deactivation by overpotentials, and 3) provide a modular system configuration that facilitates independent optimization of the electrochemical and production cells. Operating at <3 V, the CAER-Andora process currently produces ~1 mM FA/hour with >90% CO2 to FA conversion in the production cell, and progress towards the intensification of the CO 2 utilization process will be discussed.
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