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Design of Highly Active Photocatalytic System for the Removal of NOx

高活性光催化脱硝系统设计

基本信息

批准号：
02044125
负责人：
ANPO Masakazu
金额：
$ 0.9万
依托单位：
University of Osaka Prefecture
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1990
资助国家：
日本
起止时间：
1990 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02044125/
关键词：
photocatalysis NOx decomposition photocatalytic decomposition ion-echanged catalyst copper ion catalyst ESR measurement FT-IR measurement surface active site

项目摘要

Reducing global air pollution caused by NOx and SOx is currently an urgent and serious challenge. Utilization of photocatalytic processes in gas-solid systems also promising. In the present project, we have studied and found that Cu^<2+> ions supported on silica (Cu^<2+>/SiO_2) and Y-Zeolite (Cu^<2+>/Y-Zeolite) prepared by an ion-exchange method are easily reduced to Cu^+ ions when the Cu^<2+>/SiO_2 and Cu^<2+>/Y-Zeolite samples are evacuated at temperatures higher than 573 K and the reduced Cu^+ ions on silica (Cu^+/SiO_2) and Y-Zeolite (Cu^+/Y-Zeolite) catalysts can decompose NO molecules photocatalytically and stoichiometrically into N_2 and O_2 at 275 K.UV irradiation ( 270 nm) of the Cu^+/SiO_2 and Cu^+/Y-Zeolite catalysts in the presence of NO molecules at 275 K was found to lead to the decomposition of NO into N_2 and O_2. Decomposition of NO proceeds linearly with UV irradiation time at 275 K. The major products of NO decomposition were N_2 and O_2 with a minor formation of N_2 … More O and NO_2. These minor products were found to be secondary products of N, O, and NO, and the overall reaction was found to be stoichiometrical. Thus, these results clearly indicate that UV irradiation of the CU^+/SiO_2 catalyst (or Cu^+/Y-Zeolite) in the presence of NO leads to the photocatalytic decomposition of NO into N_2 and O_2 at 275 K.The physicochemical and photochemical properties of Cu^+ ions anchored onto SiO_2 and Y-Zeolite have been investigated by means of ESR measurements of the copper (Cu^<2+>) ions and of NO species adsorbed on the copper ions and dynamic photoluminescence measurements of the excited state of the copper (Cu^+) ions (3d^94s^1 electronic state), as well as product analysis of photodecomposition of NO molecules. These results indicate that the excited state of copper ions (Cu^+ ions) plays a significant role in the photocatalytic decomposition of NO molecules and the photoreaction involves an electron transfer from the excited state of the Cu^+ ion into an anti-bonding orbital of NO molecule within the lifetime of its excited state.Thus, the present results obtained with the Cu^+/SiO_2 and Cu^+/Y-Zeolite catalysts imply the possibility of their utilization as a potentially promising type of photocatalysts for the direct decomposition of NOx into N_2 and O_2 at around normal temperature. Less

减少氮氧化物和硫氧化物造成的全球空气污染是当前紧迫而严峻的挑战。在气固系统中利用光催化过程也很有前景。本课题研究发现，通过离子交换法制备的二氧化硅(Cu^<2+>/SiO_2)和Y-沸石(Cu^<2+>/Y-Zeolite)负载的Cu^<2+>离子，当Cu^<2+>/SiO_2和Cu^<2+>/Y-Zeolite样品在100℃抽真空时，很容易被还原为Cu^+离子。温度高于573 K，二氧化硅(Cu^+/SiO_2)和Y-沸石(Cu^+/Y-Zeolite)催化剂上还原的Cu^+离子可以在275 K下光催化和化学计量地将NO分子分解为N_2和O_2。Cu^+/SiO_2和Y-Zeolite在紫外光照射(270 nm)下发现Cu^+/Y-沸石催化剂在275 K下NO分子存在下导致NO分解成N_2和O_2。在275 K下，NO的分解与UV照射时间成线性关系。NO分解的主要产物是N_2和O_2，少量形成N_2…更多O和NO_2。发现这些次要产物是 N、O 和 NO 的次级产物，并且发现整个反应是化学计量的。因此，这些结果清楚地表明，在NO存在下，UV照射CU^+/SiO_2催化剂（或Cu^+/Y-Zeolite）导致NO在275 K下光催化分解为N_2和O_2。通过ESR测量，研究了锚定在SiO_2和Y-Zeolite上的Cu^+离子的物理化学和光化学性质。铜 (Cu^<2+>) 离子和吸附在铜离子上的 NO 物种，以及铜 (Cu^+) 离子激发态（3d^94s^1 电子态）的动态光致发光测量，以及 NO 分子光分解的产物分析。这些结果表明，铜离子(Cu^+离子)的激发态在NO分子的光催化分解中起着重要作用，并且光反应涉及电子在其激发态寿命内从Cu^+离子的激发态转移到NO分子的反键轨道。因此，用Cu^+/SiO_2和Cu^+/SiO_2获得的结果 Cu^+/Y-沸石催化剂意味着它们有可能作为一种有前景的光催化剂，在常温左右将NOx直接分解为N_2和O_2。较少的