Novel Deacon-like Process of HCl-Oxidation Catalyzed by RuO2

直到最近，住友化学公司才开发出一种高效而稳定的deacon样工艺，用于在RuO2上与空气进行HCl的非均相催化氧化，产生Cl2和水（住友工艺）[1]。住友工艺允许在工业（氯相关）化学中设计封闭的工艺循环，其中氯从副产品氯化氢中回收，几乎不需要额外的能源成本。本课题的主要目的是在原子尺度上对催化HCl在单晶RuO2（110）模型催化剂上被氧氧化的反应机理进行综合表征，包括催化剂的催化活性态和基本反应步骤的鉴定，激活势垒和相应过渡态的确定。我们将应用各种原位技术（包括红外光谱- rairs，表面x射线衍射- sxrd和质谱- ms）和密度泛函理论（DFT）计算来识别催化HCl氧化反应过程中表面的反应中间体，并确定RuO2催化剂的催化活性状态。从我们小组的初步实验中可以看出，RuO2（110）模型催化剂由RuO2- xclx（110）组成。我们将特别关注RuO2-xClx（110）在2HCl + 1/2O2→CI2 + H2O反应中的作用。工作催化剂RuO2-xClx（110）的原子表面结构将通过低能电子衍射（LEED）和DFT计算来确定。同样重要的是RuO2-xClx（110）催化剂在反应条件下的结构和化学稳定性，这将通过原位x射线衍射进行研究。通过DFT计算和光电子能谱，将氯化的RuO2（110）表面的电子性质与RuO2（110）表面的电子性质进行比较，以及这些电子结构的修饰如何影响催化剂表面的化学反应性。以钠作为典型的启动子（注意，NaCl被认为是类deacon过程中很有前途的助催化剂），可以调整催化剂的电子性质，从而调整催化活性。这种促进剂效应也应该通过PES和DFT计算来研究。深入了解为什么RuO2（110）是一种如此有效的HCl氧化催化剂，可能会引发对改进催化剂材料/化合物的理性探索。

Only very recently Sumitomo chemicals have developed an efficient and stable Deacon-like process for the heterogeneously catalyzed oxidation of HCl with air over RuO2 producing Cl2 and water (Sumitomo process) [1]. The Sumitomo process allows to design closed process cycles in industrial (chlorine-related) chemistry in which chlorine is recycled from the byproduct hydrogen chloride almost without additional energy cost. The main objective of this project is the comprehensive characterization of the reaction mechanism of the catalyzed HCl oxidation by oxygen over single-crystalline RuO2(110) model catalyst on the atomic scale, including the identification of the catalytically active state of the catalyst and of the elementary reaction steps, the determination of activation barriers and the corresponding transition states. We shall apply various in-situ techniques (including infrared spectroscopy-RAIRS, surface x-ray diffraction-SXRD and mass spectrornetry-MS) and density functional theory (DFT) calculations to identify the reaction intermediates on the surface during the catalyzed HCl oxidation reaction and to determine the catalytically active state of the RuO2 catalyst. From preliminary experiments in our group there is evidence that the working RuO2(110) model catalyst consists of RuO2-xClx(110). Particular attention will be drawn to the role of RuO2-xClx(110) in the reaction 2HCl + 1/2O2 → CI2 + H2O. The atomic surface structure of the working catalyst RuO2-xClx(110) will be determined by low energy electron diffraction (LEED) and DFT calculations. Equally important is the structural and chemical stability of the RuO2-xClx(110) catalyst under reaction conditions which will be studied by in situ-surface x-ray diffraction. With DFT calculations and photoelectron spectroscopy the electronic property of the chlorinated RuO2(110) surface will be compared to that of RuO2(110) and how these modifications in the electronic structure influence the chemical reactivity of the catalyst's surface. With sodium as a typical promoter (note that NaCl is considered as a promising co-catalyst in Deacon-like processes) one may tune the electronic properties of the catalyst and thereby the catalytic activity. This promoter effect should be studied by PES and DFT calculations as well. A deeper understanding why RuO2(110) is such an efficient catalyst for the oxidation of HCl may trigger a rational search for an improved catalyst materials/ compounds.