Liang Jian, Mi Yangyang, Song Ge, Peng Honggen, Li Yonglong, Yan Ran, Liu Wenming, Wang Zheng, Wu Peng, Liu Fudong
Key Laboratory of Jiangxi Province for Environment and Energy Catalysis, College of Chemistry, Nanchang University, 999 Xuefu Road, Nanchang, Jiangxi 330031, China.
Department of Civil, Environmental, and Construction Engineering, Catalysis Cluster for Renewable Energy and Chemical Transformations (REACT), NanoScience Technology Center (NSTC), University of Central Florida, Orlando, FL 32816, United States.
J Hazard Mater. 2020 Nov 5;398:122986. doi: 10.1016/j.jhazmat.2020.122986. Epub 2020 May 21.
Small pore zeolites with chabazite structure have been commercialized for selective catalytic reduction (SCR) of nitrogen oxides (NO) with ammonium (NH) from diesel exhaust. However, conventional zeolite synthesis processes detrimental effects on the environment due to the consumption of large amount of water, organic templates. Thus, this study proposed a green synthesis process with addition of minimal amount of water, structure directing agent and shortened steps to prepare nano-sized SSZ-13 (0.12 μm) using trans-crystallization strategy and exhibited enhanced performance for NO removal after copper ion-exchange. The operation temperature window (NO conversion >90 %) as well as the SO and HO resistance over the green-route prepared nano-sized SSZ-13 (178-480 °C) outperformed the conventional SSZ-13 (29.8 μm, 211-438 °C) mainly due to the much shorter diffusion path. This clearly implied that the mass transportation was key for NH-SCR of NO on such small pore zeolite catalysts, which was further confirmed via an in-depth mass transportation calculation process. These results demonstrate that the Cu-nano-sized SSZ-13 prepared by the environmental benign route has great potential to act as a new generation of deNO catalyst for diesel exhaust and provided a guideline for researchers to develop new methods to synthesize nano-catalysts for air pollution control.
具有菱沸石结构的小孔沸石已商业化用于柴油废气中氮氧化物（NO）与铵（NH）的选择性催化还原（SCR）。然而，传统的沸石合成工艺由于消耗大量水和有机模板，对环境有不利影响。因此，本研究提出了一种绿色合成工艺，通过转晶策略，添加极少量的水、结构导向剂并缩短步骤来制备纳米尺寸的SSZ-13（0.12μm），并且在铜离子交换后表现出增强的NO去除性能。绿色路线制备的纳米尺寸SSZ-13（178-480℃）的操作温度窗口（NO转化率>90%）以及抗SO和抗HO性能优于传统的SSZ-13（29.8μm，211-438℃），这主要是由于扩散路径短得多。这清楚地表明，在这种小孔沸石催化剂上，传质是NO的NH-SCR的关键，这通过深入的传质计算过程得到了进一步证实。这些结果表明，通过环境友好路线制备的Cu-纳米尺寸SSZ-13作为新一代柴油废气脱氮催化剂具有巨大潜力，并为研究人员开发用于空气污染控制的纳米催化剂新方法提供了指导。
