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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

在沸石中设计离子和/或簇大小的催化剂是特别有趣的，因为这些迷人的载体提供了独特的纳米级孔系统，不寻常的内部表面形貌和离子交换能力。沸石的孔隙结构不仅允许反应物分子扩散到沸石腔中，从而可以接触到锚定在沸石腔中的催化剂，而且还可以在随后的离子和/或簇生长过程中保持完整。对特定光催化反应所需空间的修饰是很重要的。在常规催化体系中无法实现的独特光催化性能可以在修饰的反应空间中实现。分子筛具有良好的纳米孔结构，是光催化反应中最有前途的修饰空间之一。本研究发现，活性氧化钛催化剂在CO_2和H_2O存在下，在275 K的紫外照射下，可以光催化还原CO…More _2。采用原位光致发光、紫外-可见、XAFS、ESR、FT-IR和XPS等光谱技术研究了活性氧化钛催化剂上H_2O光催化还原CO_2的特性。在二氧化钛粉末上的反应主要生成甲烷，在多孔玻璃和沸石上的反应主要生成CH_4、CH_3OH、c_2和CO。催化剂种类、CO_2/H_2O值和反应温度对phptp催化反应的产率有较大影响。系统的原位光谱研究表明，H_2O光催化还原CO_2与在表面形成的四面体配位钛氧化物的电荷转移激发态（Ti^<3+>- o ^-）^<3*>的高反应活性有关。通过对反应中间物质Ti^<3+>、H原子和C自由基的检测，在分子尺度上提出了H_2O光催化还原CO_2的反应机理。少