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Design of Active Photocatalytic System for Removal of NOx

活性光催化脱硝系统设计

基本信息

批准号：
05044110
负责人：
ANPO Masakazu
金额：
$ 2.24万
依托单位：
College of Engineering, 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：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The characterization of the Cu^+/ZSM-5 catalyst prepared from the ion-exchanged Cu^<2+>/ZSM-5 sample by the evacuation at higher temperatures has been undertaken by in situ photoluminescence, EPR,and FT-IR spectroscopy. EPR measurements of the Cu^<2+> signal indicate that the evacuation of the Cu^<2+>/ZSM-5 system at temperatures higher than 373 K leads to a decrease in the intensity of the EPR signal, suggesting that Cu^<2+> is chemically reduced to Cu^+ by this thermal vacuum treatment. Only the reduced Cu^+/ZSM-5 catalysts exhibit photoluminescence spectra at around 420-550 nm, attributed to the radiative decay from excited Cu^+ ions within the ZSM-5. The decrease in the intensity of EPR signal due to Cu^<2+> is closely related to the increase in the photoluminescence intensity due to Cu^+. The addition of NO onto the Cu^+/ZSM-5 catalyst leads to the formation Cu^<+delta+>--NO^<delta-> adducts and dynamic quenching of the photoluminescence, suggesting that Cu^+ reacts with NO mot only in the ground state but also in the excited state. UV-irradiation of the Cu^+/ZSM-5 catalyst in the presence of NO leads to the photocatalytic decomposition of NO into N_2 and O_2 at temperatures as low as 275 K.In situ photoluminescence, EPR,and FT-IR measurements suggest that a local charge separation involving electron transfer from the excited Cu^+ ion to the pi-anti-bonding orbital of NO is involved in the decomposition of NO on the catalyst under UV-irradiation.

用原位光致发光、电子顺磁共振和傅立叶变换红外光谱对离子交换法制备的Cu2+/ZSM-5催化剂进行了表征。对Cu2+/ZSM-5体系的EPR测量表明，在高于373K的温度下，Cu2+/ZSM-5体系的电子顺磁共振信号强度降低，表明这种热真空处理使Cu2+被化学还原为Cu2+。只有还原的Cu2+/ZSM-5催化剂在420-550 nm附近表现出光致发光，这归因于ZSM-5中被激发的Cu2+离子的辐射衰减。Cu2+引起的EPR信号强度的减弱与Cu2+引起的光致发光强度的增强密切相关。在Cu2+/ZSM-5催化剂上加入NO后，生成了加合物Cu^&lt；+Delta+&gt；--NO^&lt；Delta-gt；，光致发光动态猝灭，表明Cu2+不仅在基态下与NO反应，而且在激发态下与NO反应.在含有NO的Cu2+/ZSM-5催化剂上进行紫外光照射，可以在275K的温度下将NO光催化分解为N_2和O_2。原位光致发光、EPR和FT-IR测试表明，在紫外光照射下，NO在催化剂上发生局部电荷分离，电子从被激发的Cu2+离子转移到NO的pi反键轨道。