Enhanced electro-reduction of NO to NH 3 on Pt cathode at electro-scrubber

Abstract

Besides cheaper electrodes used in NH₃ product formation during NO degradation by mediated electrochemical reduction (MER), a specific electrode that can perform direct electrochemical reduction (DER) and MER of NO is an added advantage. In the present study, a Pt electrode was used to examine NO degradation through NH₃ formation during the electro-scrubbing process. Initially, the DER of NO was tested on a Pt electrode to determine if the DER of NO is possible. The NO degradation by only absorption, DER on Pt, and MER using electrogenerated [Ni(I)(CN)₄]³⁻ showed that a combination of DER and MER increased the NO degradation efficiency. In addition, the online FTIR spectra obtained under different conditions showed that the product formed was NH₃, either from the DER or MER during electro-scrubbing. The feed gas flow rate and feed concentration results of NH₃ formation revealed an additional chemical reaction that was influenced by the Pt electrode in addition to the DER and MER processes. Furthermore, the degradation efficiency of NO when using the Pt electrode increased to 90% compared to that of the Cu electrode (65%), which showed that Pt follows a combination of DER and MER processes. Based on the gas-phase FTIR results of NH₃ formation during NO degradation, higher NH₃ production (0.32 mg/h) was obtained when using a Pt electrode than that using a Cu electrode (0.21 mg/h), highlighting the specificity of the Pt electrode in NH₃ formation during the degradation of NO gas.