铈锆复合氧化物催化HCl氧化中相互作用机制

采用浸渍法制备了不同负载量的ZrO₂/CeO₂·（xZr/Ce）和CeO₂/ZrO₂·（yCe/Zr）两组催化剂。并采用XRD、Raman、N₂-Sorption、TEM和H₂-TPR等手段对xZr/Ce和yCe/Zr的结构和性质进行表征，并结合HCl催化氧化活性研究CeO₂与ZrO₂在反应体系中的相互作用。结果显示，CeO₂表面掺杂适量的Zr⁴⁺可以增加xZr/Ce表面氧空位浓度，提高其HCl氧化反应活性；但当CeO₂表面掺杂过量的Zr⁴⁺，Zr元素会以ZrO₂的形式存在于xZr/Ce表面，覆盖氧空位，降低了xZr/Ce的反应活性。对于yCe/Zr催化剂，ZrO₂表面高分散的CeO₂有利于催化活性的提高，但ZrO₂表层负载的CeO₂对催化活性的贡献具有阈值，当CeO₂负载量超过10%后，额外增加的铈物种对催化活性已无显著促进作用；对比发现xZr/Ce的氧空位主要来自于铈锆固溶体，yCe/Zr的氧空位主要来自于高分散的CeO₂，由铈锆固溶体产生的氧空位对活性提升更有利；与纯组分CeO₂相比，xZr/Ce与yCe/Zr两组催化剂在苛刻条件下的长期稳定性测试中均表现出高反应稳定性。

Interaction between CeO2 and ZrO2 in HCl catalytic oxidation

ZrO₂/CeO₂ (xZr/Ce) and CeO₂/ZrO₂ (yCe/Zr) catalysts with different loading were prepared by wet impregnation method. XRD, Raman, N₂-Sorption, TEM and H₂-TPR were used to study the interaction between CeO₂ and ZrO₂ in the recycling of Cl₂ from HCl oxidation. The results showed that the doping appropriate amount of zirconium species on the surface of CeO₂ could increase the concentration of oxygen vacancy over xZr/Ce, which was in favor of enhancing the activity of HCl oxidation. When there were too many Zr⁴⁺ doping on the surface of CeO₂, a part of Zr elements would be presented as ZrO₂ over the surface of xZr/Ce and the oxygen vacancy was covered, which was unfavorable to the activity of HCl oxidation. For yCe/Zr catalyst, the dispersive CeO₂ over ZrO₂ was beneficial to the improvement of the catalytic activity, but the increase of catalytic activity would slow down when the loading of CeO₂ exceed 10%. By comparing xZr/Ce with yCe/Zr catalysts, the oxygen vacancy of xZr/Ce was mainly formed by Ce-Zr solid solution, while the oxygen vacancy of yCe/Zr was formed by highly dispersive CeO₂. It was found that the oxygen vacancy produced by different structure have different effects on the activity. The oxygen vacancies produced by Ce-Zr solid solution are more favorable to the activity enhancement. The ability of chlorine resistance of xZr/Ce and yCe/Zr catalysts behaved a superior stability in the long-term test compared to pure CeO₂.