|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,700,000 (Direct Cost : ¥1,700,000)
There has been consoderable interest in the specific interaction between a dinitrogen molecule and solid materials, from the viewpoints of dinitrogen-fixation. Of particular interest has been the characterization of the chemical bonding nature between dinitrogen and the active center existing on surfaces of such solid materials. We have found that a copper-ion-excahnged ZSM-5-type zeolite strongly adsorbs N_2 at room temperature, givign the intence infrared absorption band at 2295 cm^<-1>. The focus of the present investigation is on understanding the state of N_2 adsorption sites and also the bonding state between copper ion and N_2 in more detail. Through this investigation, we have a potential to use this material as N_2-separation, -fixation, and -activation catalysts.
It is also found tha the amount of N_2adsorbed, as well as CO amount, is increased with increasing exchange capacity of copper ion in this zeolite. The behavior of monolayr capcity of N_2 with ion exchange capacity ha
s the same tendency with the area of 2151 cm^<-1> band resulting from the interaction with CO molecule. The IR spectra of the sample on which N_2 gas was introduced are measured after the adsorption and desorption of CO on cooper-ion-exchanged ZSM-type zeolite which was previously evacuated at 873 K.Photoemission spectra are also measured in N_2 adsorption stages, and it is found that the observed emission band due to Cu^4 decend its intencity with increasing N_2 pressures. These results are explained by considering that the monovalent copper ion formed in the evacuation process in vacuo is the important site for N_2 adsorption. Furthermore, the site giving an IR band at 2151 cm^<-1> through the interaction with CO molecules, as well as 540 nm-band in emission spectra, can be important one in the N_2 adsorption. Taking account of the XAFS results reported previously, it can be tentatively said that this site takes a gcometrical structure of the three- or four-coordinated one around copper through the interaction with CO or N_2 molecule