Absorption of Nitrogen Oxides into Sodium Hydroxide Solution in a Rotating Packed Bed with Preoxidation by Ozone

• Published in: Energy & fuels 2017-10, Vol.31 (10), p.11019-11025
• Main Authors: Sun, Baochang, Sheng, Miaopeng, Gao, Wenlei, Zhang, Liangliang, Arowo, Moses, Liang, Yan, Shao, Lei, Chu, Guang-Wen, Zou, Haikui, Chen, Jian-Feng
• Format: Article
• Language: English
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.7b01417

This study employed a rotating packed bed (RPB) to enhance the absorption performance of nitrogen oxides (NO x ) into sodium hydroxide (NaOH) solution with the preoxidation of NO by ozone. The absorption performance of NO x was evaluated in terms of its removal efficiency (η) from a gas stream under various operating conditions including O3/NO x molar ratio (MR), rotation speed of the RPB (N), liquid flow rate (L), NaOH concentration (C NaOH), inlet NO x concentration (C NO x ), and using time (t). Also, the corresponding effect of adding oxidants (NaClO, H2O2, and KMnO4) and a reductant (CO­(NH2)2) into the NaOH solution on NO x removal efficiency was investigated. Results indicated that preoxidation of NO by O3 significantly improved NO x removal efficiency and the removal efficiency increased with increasing O3/NO x molar ratio, NaOH concentration, and liquid flow rate but decreased with increase in inlet NO x concentration and using time. Additionally, NO x removal efficiency first increased and then decreased with increasing rotation speed of the RPB. Both the oxidation and reduction additives enhanced NO x removal efficiency, and the order of enhancement was found to be KMnO4 > H2O2 > CO­(NH2)2 > NaClO. These results further indicate that the hydrolysis reactions of NO x are the rate-determining steps in the NO x absorption process and, thus, the main factors hindering NO x removal during the wet scrubbing process. This work demonstrates that RPB has great potential for removal of NO x by a wet scrubbing process in view of the small size of the RPB, low temperature, and the short gas retention time of 0.27 s applied in this work.