화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.107, No.21, 4971-4974, 2003
Low-temperature-programmed replacement of nitrogen by hydrogen in pores of mordenite
Nitrogen molecules were filled in pores of NaMOR by calcination at T-c = 773 K under nitrogen atmosphere and then replaced by hydrogen molecules. The replacement was performed in a specially designed low-temperature routine operated between 173 and 423 K with a flow of 10% hydrogen in nitrogen. The obtained replacement profile comprised four kinds of phenomena, i.e., rapid replacement (R,) of gaseous phase nitrogen in pores by hydrogen, hindered replacement (Rh) of nitrogen condensed around sodium ions, activated chemisorption of (C) of nitrogen molecules on sodium ions, and desorption (D) of chemisorbed nitrogen from Na+ site. The R, exhibited two major peaks at similar to185 and similar to240 K for nitrogen in 12-MR channel (R-rc) and in 8-MR side pocket (R-rp). The R-h was delayed up to 350 K due to hindrance by sodium ions. Both the C and the D exhibited three sharp peaks for sodium ions at three kinds of environments in MOR structure.