1993 年 14 巻 10 号 p. 623-629
Nitrogen, one of the most chemically inactive molecules, does not adsorb on A12O3 and Pt/Al2O3 catalysts at room temperature. However, once it was excited by plasma discharge using radio-frequency (13.56 MHZ), activated adsorption of nitrogen occurred on Pt/Al2O3 and Al2O3 at room temperature. The characterization of chemisorbed N2 and its chemical reactivity with hydrogen have been studied by temperature programmed desorption (TPD) and infrared spectroscopy (IR). The adsorbed nitrogen on Pt/Al2O3 or Al2O3 was desorbed below 300°C by TPD, and IR spectra of the adsorbed nitrogen on Pt/Al2O3 were observed at ca . 2260 and 2230 cm-1, which were assigned to N-N stretching vibration. Since almost the same absorption bands were observed with N2 on Al2O3, it was considered that N2(a) was chemisorbed mainly on the Al2O3 support . The H2 exposure experiment at room temperature showed that the infrared bands of N2(a) on the Al2O3 support (without Pt) did not change, but the intensity of the spectrum of N2 on the Pt/Al2O3 catalyst decreased significantly with time. Moreover, NH3 was detected in the liquid N2 trap by GC after the TPD run. It was proposed that the N2(a) reacted with the hydrogen spilt-over from the Pt surface to form other species like NHx(a) (X=1∼3) even at room temperature.