The effect of weak acid anions on the selective catalytic wet air oxidation of aqueous ammonia to nitrogen

Zidan Wang; Sohaib Hameed; Yaoyao Wen; Nuowei Zhang; Hengjun Gai; Jinbao Zheng; Bing H Chen

doi:10.1038/s41598-017-04207-5

The effect of weak acid anions on the selective catalytic wet air oxidation of aqueous ammonia to nitrogen

Sci Rep. 2017 Jun 20;7(1):3911. doi: 10.1038/s41598-017-04207-5.

Authors

Zidan Wang¹, Sohaib Hameed¹, Yaoyao Wen¹, Nuowei Zhang², Hengjun Gai³, Jinbao Zheng³, Bing H Chen⁴

Affiliations

¹ Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Xiamen University, Xiamen, 361005, PR China.
² Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Xiamen University, Xiamen, 361005, PR China. zhnw@xmu.edu.cn.
³ Qingdao University of Science and Technology, Shandong Qingdao, 266042, China.
⁴ Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, Xiamen University, Xiamen, 361005, PR China. chenbh@xmu.edu.cn.

Abstract

In this work, the effect of weak acid anions on the ammonia removal has been extensively studied for the process of selective catalytic wet air oxidation (CWAO) of ammonia to nitrogen. It is found that the presence of weak acid anions can effectively enhance the ammonia conversion and selectivity towards nitrogen. The combination between the weak acid anions and H⁺ to produce weak acid molecules is responsible for such enhancement. Firstly, the H⁺ consumption of weak acid anions can increase the NH₃ concentration and thus the reactivity of ammonia oxidation, due to the shift to NH₃ on the equilibrium of NH₄⁺/NH₃. Secondly, the competition combination with H⁺ between the weak acid anions and NO₂^- can increase the concentration of NO₂^- and thus boosts the disproportionation reaction between NH₄⁺ and NO₂^- to produce nitrogen.

Publication types

Research Support, Non-U.S. Gov't