Homogeneous Ni(I)tetra Sulfonated Phthalocyanine Electrocatalyst Generated at Low Overpotential Clubbed with a Wet‐Scrubbing Column for High Efficiency NO Reduction to NH3

• Published in: ChemistrySelect (Weinheim) Vol. 6; no. 43; pp. 11980 - 11984
• Main Authors: Muthuraman, G., Silambarasan, P., Moon, I.‐S.
• Format: Journal Article
• Language: English
• Published: 22.11.2021
• Subjects: Electro scrubbing; Environmental chemistry; NH3 generation; NO removal; Pollution control
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202103406

Although the degradation of NO gas to a less toxic form is a promising strategy to help solve atmospheric health and ozone depletion problems, conversion to a useful gas is a recent strategy. The generation of NH3 from NO with high efficiency per catalyst area or weight is in the early stages. In this investigation, a tetra sulfonated phthalocyanine with a Ni(II) (Ni(II)TSPc) complex was used to produce a low valent homogenous electrocatalyst Ni(I)TSPc in an alkaline medium at a lower overpotential. Ni(I)TSPc formation at a lower overpotential was demonstrated by the initial change in oxidation/reduction potential from 25 mV to −360 mV during electrolysis, peak potential change in cyclic voltammetry, and UV‐Vis spectral analysis. A potentiometric titration method used to quantify the electrogenerated Ni(I)TSPc revealed 90 % efficiency in 1 h. The decrease of Ni(I)TSPc concentration when contacting NO gas at the wet scrubber column showed that the NO removal process followed a Ni(I)TSPc (Ni(I)) mediation or mediated electrocatalytic reduction (MER) process. The NO removal efficiency reached almost 100 % at a 0.2 L/min gas flow rate of 20 ppm. The selective formation of NH3 with a maximum of 1492 μmol/g Ni(I) was achieved for the first time in the homogeneous electrocatalytic reduction process. The developed process generated NH3 from NO gas and has the potential for scale‐up. Electro‐generation of low‐valent Ni(I)TSPc at less potential (−0.36 V) in 1 M KOH solution enhances the Ni(I)TSPc formation to 90 % and it facilitates the NH3 formation from NO sustainably without additional reaction at electro‐scrubbing under continuous removal process. Using the present approach, achieved 1469 μmol/gm (Ni(I)) h by electrogenerated Ni(I)tetra sulfonated phthalocyanine mediator at electro‐scrubbing process.