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首页> 外文期刊>ACS catalysis >SO2 Poisoning of the NH3-SCR Reaction over Cu-SAPO-34: Effect of Ammonium Sulfate versus Other S-Containing Species
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SO2 Poisoning of the NH3-SCR Reaction over Cu-SAPO-34: Effect of Ammonium Sulfate versus Other S-Containing Species

机译：Cu-SAPO-34上的NH3-SCR反应的SO2中毒：硫酸铵与其他含S物质的影响

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SO2 poisoning of NH3-SCR over Cu-SAPO-34 was studied, specifically to evaluate the forms/states of stored S and the effect of such species on low-temperature NOx reduction activity. Two primary sulfur species types were observed and were found to be interchangeable depending on whether NH3 was available or not. In one case both ammonium sulfate and Cu sulfate species could be present and in the other only Cu sulfate species. Cu sulfate, in the absence of ammonia, was found in three different states/forms, identified by three desorption features during temperature programmed desorption (TPD) experiments. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of NO adsorption was used to investigate the nature and accessibility of the Cu species before and after sulfate formation, without the interference of ammonium sulfate; these data revealed that the Cu2+ inside the six-membered rings was completely blocked by sulfur and that the nature of the [CuOH](+) close to the eight-membered ring changed. In comparing the effect of different forms of S on low-temperature NOx reduction activity, ammonium sulfate had the greatest impact on performance loss. Interestingly, the results also show that ammonium sulfate can actually play a role as a SCR reactant, likely analogous to the mechanism involving ammonium nitrate. Ammonium sulfate decomposes at temperatures as low as similar to 300-350 degrees C, whereas higher temperatures (>480 degrees C) were needed to desorb other S-containing species. This appears favorable, as NH3 can react with preadsorbed sulfur on the catalyst to form ammonium sulfate, which decomposes at lower temperatures in comparison to the other sulfate forms.
机译：研究了Cu-SAPO-34上NH3-SCR的SO2中毒现象，专门评估了储存的S的形式/状态以及此类物质对低温NOx还原活性的影响。观察到两种主要的硫物质类型，并且根据是否可使用NH3可以互换。在一种情况下，硫酸铵和硫酸铜都可能同时存在，而在另一种情况下，只有硫酸铜才存在。在无氨的情况下，硫酸铜以三种不同的状态/形式存在，在程序升温脱附（TPD）实验过程中通过三种脱附特征得以识别。利用NO吸收的漫反射红外傅里叶变换光谱法（DRIFTS）研究了硫酸盐形成前后Cu物种的性质和可及性，不受硫酸铵的干扰。这些数据表明，六元环内部的Cu2 +被硫完全封闭，并且接近八元环的[CuOH]（+）的性质发生了变化。在比较不同形式的S对低温NOx还原活性的影响时，硫酸铵对性能损失的影响最大。有趣的是，结果还表明，硫酸铵实际上可以充当SCR反应物，可能类似于涉及硝酸铵的机理。硫酸铵在类似于300-350摄氏度的低温下分解，而需要更高的温度（> 480摄氏度）才能解吸其他含S物质。这似乎是有利的，因为NH 3可以与催化剂上预吸附的硫反应形成硫酸铵，与其他硫酸盐形式相比，硫酸铵在较低的温度下分解。

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