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Preparation of Photocatalysts in Micro-pores of Zeolite and Their Reaction Dynamics

沸石微孔光催化剂的制备及其反应动力学

基本信息

批准号：
05453123
负责人：
ANPO Masakazu
金额：
$ 3.97万
依托单位：
University of Osaka Prefecture
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05453123/
关键词：
Photocatalyst Micro-pore Zeolite Dynamics Anchored catalyst Photosynthesis Reduction of CO_2 Quantum effect

项目摘要

It is of special interest to design the ion and/or cluster size catalysts within the zeolites because these fascinating supports offer unique nano-scaled pore systems, unusual internal surface tipology, and ion-exchange capacities. The pore structure of the zeolite not only allows for reactant molecules to diffuse into the ppre where in can access the catalyst anchored within the zeolite cavities, but also can remain intact during subsequent ion and/or cluster growth. The modification of the space required for a specific photocatalytic reactions is important. Unique photocatalytic properties which cannot be realized in normal catalytic systems can be expected in modified reaction spaces. Zeolites with well-defined nano-pore structure provide one of the most promising modified spaces for photocatalytic reactions.In the present study, it was found that UV-irradiation of the active titanium oxide catalysts in the presence of CO_2 and H_2O at 275 K led to the photocatalytic reduction of CO … More _2. The characteristic features of the photocatalytic reduction of CO_2 with H_2O on the active titanium oxide catalysts were investigated by in situ photoluminescence, UV-Vis, XAFS,ESR,FT-IR and XPS spectroscopic techniques.The reactions on TiO_2 powders produced methane as the major product, while, on the highly dispersed titanium oxide anchored on a porous glass and zeolites the formation of CH_4, CH_3OH,C_2-compounds and CO was observed as the major products. The yields of the phptpcatalytic reactions strongly depended on the type of catalysts, the values of CO_2/H_2O and the reaction temperatures. In situ spectroscopic studies of the system indicated that the photocatalytic reduction of CO_2 with H_2O is linked to the much higher reactivity of the charge transfer excited state, i.e., (Ti^<3+>-O^-)^<3*> of the tetrahedral coordinated titanium oxides species formed on the surfaces. Based on the detection of reaction intermediate species such as Ti^<3+>, H atoms, and C radicals, reaction mechanism for the photocatalytic reduction of CO_2 with H_2O has been proposed on a molecular scale. Less

在沸石内设计离子和/或簇尺寸的催化剂特别令人感兴趣，因为这些令人着迷的载体提供了独特的纳米级孔隙系统、不寻常的内表面拓扑结构和离子交换能力。沸石的孔结构不仅允许反应物分子扩散到ppre中，其中可以接触固定在沸石腔内的催化剂，而且还可以在随后的离子和/或簇生长期间保持完整。特定光催化反应所需空间的修改很重要。在改进的反应空间中可以期待在普通催化系统中无法实现的独特光催化性能。具有明确纳米孔结构的沸石为光催化反应提供了最有前途的修饰空间之一。在本研究中，发现在275 K下CO_2和H_2O存在下，活性二氧化钛催化剂的紫外线照射导致CO的光催化还原……更多_2。采用原位光致发光、UV-Vis、XAFS、ESR、FT-IR和XPS光谱技术研究了活性二氧化钛催化剂上H_2O光催化还原CO_2的特征。TiO_2粉末上的反应主要产物是甲烷，而在多孔玻璃上锚定的高度分散的二氧化钛上的反应主要产物是甲烷。观察到沸石的主要产物是CH_4、CH_3OH、C_2-化合物和CO的形成。 phptp催化反应的产率很大程度上取决于催化剂的类型、CO_2/H_2O的值和反应温度。系统的原位光谱研究表明，H_2O对CO_2的光催化还原与电荷转移激发态的更高反应活性有关，即表面形成的四面体配位氧化钛物种的(Ti^<3+>-O^-)^<3*>。基于Ti^3+、H原子和C自由基等反应中间体的检测，提出了分子尺度上H_2O光催化还原CO_2的反应机理。较少的