In-situ electrochemical NOx removal process for the lean-burn engine exhaust based on carbon black gas diffusion electrode. (10th May 2017)

• Record Type: Journal Article
• Authors: Qi, Zhaoyu; Dong, Heng; Yu, Han; Zhao, Min; Yu, Hongbing
• Is Part Of: Journal of cleaner production. Volume 151(2017)
• Page Start: 465
• Page End: 474
• Publication Date: 2017-05-10
• Subjects: Lean-burn engine exhaust -- Electrochemical oxidation -- Gas diffusion electrode -- NO adsorption -- NOx removal mechanism; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2017.03.085
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: With the aim to remove NOx from the lean-burn engine exhaust, a novel in-situ electrochemical device was designed using carbon black-based gas diffusion electrode (GDE) as cathode. Taking advantage of the excessive O2 from the exhaust, in-situ electro-generation of H2 O2 from oxygen reduction reaction (ORR) under catalysis of the GDE could oxidize NOx to NO3 − . The highest NOx removal efficiency was 77.7% for 1000 ppm NOx with energy consumption of 1.327 W cm −2 cm −3 . The electrochemical NOx removal pathway was proposed that, as NO and O2 were adsorbed on different sites in the catalyst layer (CL), electro-generated H2 O2 attacked the C―N adsorption bonds mostly in the nitro compounds to oxidize adsorbed NO to NO3 −, while NO2 was directly oxidized by the produced H2 O2 in the electrolyte. The NOx removal efficiency is mainly controlled by the NO adsorption rate as well as the H2 O2 oxidation rate, and the former is the dominant factor. This in-situ electrochemical NOx removal system exhibited properties of energy-saving, low–cost and environmental compatibility, indicating great potential for industrial application. Graphical abstract: Proposed reaction pathways of electrochemical NOx removal by H2 O2 electro-generated on the carbon black-based gas diffusion electrodes in situ . Highlights: Electrochemical NOx removal is established using gas diffusion electrode. Efficient NOx removal (77.7% for 1000 ppm NOx ) is achieved. Low energy consumption (0.375–1.327 W cm −2 cm −3 ) is obtained. Characterization revealed NOx adsorption sites were separated with ORR sites. Possible reaction pathways of NOx adsorption and oxidation were discussed.