The Ce-Cu-SAPO-18 catalysts were prepared by the ion exchange method. The Ce-Cu-SAPO-18-2 catalyst with a Ce content of 1.24 wt% showed the excellent NH₃-SCR activity. Characterization results demonstrated that the Ce-Cu-SAPO-18-2 catalyst possessed strong redox ability and high reactive nitrate and NH₃ species, which were responsible for the remarkable SCR performance. The best-performing Ce-Cu-SAPO-18-2 catalyst displayed a broad operation temperature window, a result possibly due to the improvement of physicochemical properties and acceleration of reaction rate in the Langmuir−Hinshelwood (L−H) and Eley−Rideal (E−R) mechanisms. The higher amounts of isolated Cu²⁺ species and acid sites in Ce-Cu-SAPO-18-2 promoted the adsorption and activation of NO, and facilitated the reaction between the adsorbed NO_x species and the gas-phase NH₃ molecules according to the L−H mechanism. For the E−R mechanism, the NH₃ (L) species were the crucial initial intermediates for NH₃ activation, and the more amount of Lewis acid sites in the Ce-Cu-SAPO-18-2 sample originated from its coordinatively unsaturated cationic sites benefited the reaction between the adsorbed NH₃ species and NO molecules. Based on the results of in situ DRIFTS characterization, we believe that the L−H mechanism dominated the NH₃-SCR reaction at low temperatures, and the doping of Ce in the catalyst improved the L−H and E−R reactions at low temperatures.

通过离子交换法制备了Ce-Cu-SAPO-18催化剂。Ce含量为1.24wt％的Ce-Cu-SAPO-18-2催化剂显示出优异的NH ₃ -SCR活性。表征结果表明，Ce-Cu-SAPO-18-2催化剂具有较强的氧化还原能力和较高的反应性硝酸盐和NH ₃种类，这是SCR性能优异的原因。表现最佳的Ce-Cu-SAPO-18-2催化剂显示出较宽的操作温度范围，其结果可能是由于Langmuir-Hinshelwood（L-H）和Eley-Rideal的理化性质和反应速率的提高所致（ER）机制。分离出的Cu ^2+的量更高根据L-H机理，Ce-Cu-SAPO-18-2中的碳原子类型和酸位促进了NO的吸附和活化，并促进了吸附的NO _x物种与气相NH ₃分子之间的反应。对于E-R机理，NH ₃（L）物种是NH ₃活化的关键初始中间体，并且Ce-Cu-SAPO-18-2样品中更多的路易斯酸位源自其配位不饱和阳离子这些位点有利于吸附的NH ₃物种与NO分子之间的反应。根据原位DRIFTS表征的结果，我们认为L-H机制主导了NH ₃低温下的-SCR反应以及催化剂中Ce的掺杂改善了低温下的LH和E-R反应。