【摘 要】
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Ag/Al2O3催化碳氢化合物选择性还原(HC-SCR)氮氧化物(NOx)是有望实际应用于柴油机尾气治理的技术之一.催化剂表面的银物种在净化NOx中起到了至关重要的作用.本文通过X射线光
【出 处】
：
第七届国际分子模拟与信息技术应用学术会议
论文部分内容阅读
Ag/Al2O3催化碳氢化合物选择性还原(HC-SCR)氮氧化物(NOx)是有望实际应用于柴油机尾气治理的技术之一.催化剂表面的银物种在净化NOx中起到了至关重要的作用.本文通过X射线光电子能谱(XPS)、X射线近边吸收光谱(XANES)、X射线拓展边精细结构(EXAFS)联合理论计算(DFT)的方法研究了银物种的特征.通过负载梯度浓度的银,发现在负载量小于2wt％时,氧化态银为主导且催化活性优良.在1 wt％负载量时,银离子是主要银物种且其活性最佳.当负载量增至2wt％,低温活性提高而高温活性下降,银离子仍为主要物种且伴随有Ag-Ag配位壳层出现.DFT模拟了银离子和氧化银簇(Agn,1≤n≤4)负载于载体氧化铝之上的模型,结构参数与EXAFS实验表征结果十分吻合.对比不同模型的能隙大小发现:Ag离子锚定于AlⅢ位有利杂化Ag,O,Al原子轨道降低能隙进而提升催化活性.
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