Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Environ Sci Technol. 2021 Dec 7;55(23):16175-16183. doi: 10.1021/acs.est.1c06475. Epub 2021 Nov 15.
Cu-SSZ-39 exhibits excellent hydrothermal stability and is expected to be used for NO purification in diesel vehicles. In this work, the selective catalytic reduction (SCR) activities in the presence or absence of NO were tested over Cu-SSZ-39 catalysts with different Cu contents. The results showed that the NO conversion of Cu-SSZ-39 was improved by NO when NO/NO = 0.5, especially for the catalysts with low Cu loadings. The kinetic studies showed two kinetic regimes for fast SCR from 150 to 220 °C due to a change in the rate-controlling mechanism. The activity test and diffuse reflectance infrared Fourier transform spectra demonstrated that the reduction of NO mainly occurred on the Cu species in the absence of feed NO, and when NO/NO = 1, NO could react with NHNO on the Brønsted acid sites in addition to undergoing reduction on Cu species. Thus, NO can promote the SCR reaction over Cu-SSZ-39 by facilitating the formation of surface nitrate species.
Cu-SSZ-39 表现出优异的水热稳定性，有望用于柴油车中 NO 的净化。在这项工作中，在不同 Cu 含量的 Cu-SSZ-39 催化剂上测试了存在或不存在 NO 的选择性催化还原 (SCR) 活性。结果表明，当 NO/NO = 0.5 时，Cu-SSZ-39 的 NO 转化率通过 NO 得到提高，特别是对于低 Cu 负载的催化剂。动力学研究表明，由于速率控制机制的变化，在 150 至 220°C 之间存在快速 SCR 的两个动力学区。活性测试和漫反射红外傅里叶变换光谱表明，在没有进料 NO 的情况下，NO 的还原主要发生在 Cu 物种上，当 NO/NO = 1 时，NO 除了在 Cu 物种上进行还原外，还可以与 Brønsted 酸位上的 NHNO 反应。因此，NO 可以通过促进表面硝酸盐物种的形成来促进 Cu-SSZ-39 上的 SCR 反应。
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