School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China.
Phys Chem Chem Phys. 2019 Oct 9;21(39):22113-22120. doi: 10.1039/c9cp04519h.
Cu/SAPO-34 catalysts were prepared by different solid-state ion exchange methods, i.e., mechanical mixing (Cu/SAPO-34-M) and ball milling (Cu/SAPO-34-B), and were used for selective catalytic reduction of NOx with NH3 (NH3-SCR) reaction. Compared with Cu/SAPO-34-M, Cu/SAPO-34-B exhibited more excellent NH3-SCR catalytic activity. Various characterization methods, including XRD, SEM, N2 adsorption-desorption, UV-vis, H2-TPR, EPR, NO + O2-TPD, NH3-TPD, and in situ DRIFTS, were used to elucidate their different catalytic performances. The characterization results suggested that ball milling could be beneficial for increasing the amount of isolated Cu2+ ions in the Cu/SAPO-34 catalyst. In comparison with Cu/SAPO-34-M, Cu/SAPO-34-B had more isolated Cu2+ ions, which mainly contributed to the NOx adsorption and Lewis acid sites. Furthermore, ball milling could improve the redox property of the Cu/SAPO-34 catalyst. The in situ DRIFTS results verified that NH3 adsorbed on Lewis acid sites were more active than those adsorbed on Brønsted acid sites. Therefore, it was believed that ball milling was a suitable method to prepare more efficient Cu/SAPO-34 catalysts for NOx removal from diesel exhaust.
Cu/SAPO-34 催化剂通过不同的固相反位交换方法制备，即机械混合（Cu/SAPO-34-M）和球磨（Cu/SAPO-34-B），并用于选择性催化还原 NOx 与 NH3（NH3-SCR）反应。与 Cu/SAPO-34-M 相比，Cu/SAPO-34-B 表现出更优异的 NH3-SCR 催化活性。使用各种表征方法，包括 XRD、SEM、N2 吸附-解吸、UV-vis、H2-TPR、EPR、NO + O2-TPD、NH3-TPD 和原位 DRIFTS，阐明了它们不同的催化性能。表征结果表明，球磨有利于增加 Cu/SAPO-34 催化剂中孤立的 Cu2+离子的数量。与 Cu/SAPO-34-M 相比，Cu/SAPO-34-B 具有更多的孤立的 Cu2+离子，这主要归因于 NOx 的吸附和路易斯酸位。此外，球磨可以改善 Cu/SAPO-34 催化剂的氧化还原性能。原位 DRIFTS 结果证实，Lewis 酸位上吸附的 NH3 比 Brønsted 酸位上吸附的 NH3 更活跃。因此，人们认为球磨是一种合适的方法，可以制备更高效的 Cu/SAPO-34 催化剂，用于去除柴油机尾气中的 NOx。
