Ion Exchange of One-Pot Synthesized Cu-SAPO-44 with NH4NO3 to Promote Cu Dispersion and Activity for Selective Catalytic Reduction of NOx with NH3
Ion Exchange of One-Pot Synthesized Cu-SAPO-44 with NH4NO3 to Promote Cu Dispersion and Activity for Selective Catalytic Reduction of NOx with NH3
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DOI：
10.3390/catal9110882
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发表时间：
2019-10
期刊：
影响因子：
3.9
通讯作者：
Nana Zhang;Ying Xin;Qian Li;Xicheng Ma;Yong-xin Qi;Lirong Zheng;Zhaoliang Zhang
中科院分区：
文献类型：
--
作者：
Nana Zhang;Ying Xin;Qian Li;Xicheng Ma;Yong-xin Qi;Lirong Zheng;Zhaoliang Zhang
含铜CHA型（Cu-CHA）分子筛因其优异的低温活性和水热稳定性，在NH3-SCR选择性催化还原NOx反应中得到了广泛的研究。本文以双胺为模板剂，采用一锅法合成了一系列Cu-SAPO-44分子筛。采用X射线粉末衍射（XRD）、N2吸附-脱附等温线、电感耦合等离子体（ICP）、场发射扫描电子显微镜（FE-SEM）、高分辨透射电子显微镜（HRTEM）、X射线吸收精细结构（XAFS）和H2-程序升温还原（H2-TPR）等手段研究了硝酸铵处理对Cu物种的影响。结果表明，在原始样品中，除了主要的SAPO-44结构之外，通过XRD检测到CuO相。经硝酸铵离子交换后，ICP分析表明，铜含量大大降低。通过SEM、TEM和H2-TPR证实了CuO团聚体的去除和高度分散的CuO纳米颗粒（~2.36 nm）的存在。此外，一个孤立的Cu 2+的比例显着增加，来自XAFS。结果，在较高温度（≥350 °C）下的活性大大提高。
Cu-containing CHA type (Cu-CHA) zeolites have been widely investigated owing to their excellent low-temperature activity and high hydrothermal stability in selective catalytic reduction of NOx with NH3 (NH3-SCR). Herein, a series of Cu-SAPO-44 zeolites were prepared by one-pot method with dual-amine templates and the subsequent ion exchange (IE) with NH4NO3. The effect of NH4NO3 treatment on Cu species was investigated by X-ray powder diffraction (XRD), N2 adsorption-desorption isotherm, inductively coupled plasma (ICP); field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HRTEM), X-ray absorption fine structure (XAFS), and H2-temperature-programmed reduction (H2-TPR). The results indicated that—besides the main SAPO-44 structure—the CuO phase was detected by XRD in original samples. After IE with NH4NO3, the Cu contents decreased greatly from ICP analysis. The removal of CuO agglomerations and the presence of highly dispersed CuO nanoparticles (~2.36 nm) were confirmed by SEM, TEM and H2-TPR. Furthermore, a significant increase in the proportion of isolated Cu2+ was derived from XAFS. As a result, the activity at higher temperature (≥350 °C) was improved a lot.