ADSORPTION OF NITROGEN MONOXIDE ON IRON-OXIDE HYDROXIDES AND THEIR CALCINATED PRODUCTS

The adsorption of NO on α-, β-, and γ FeOOH has been measured by means of a gravimetric; method at 30°C. The adsorption isotherms below 100 Torr were well expressed by the Langmuir formula. The Langmuir constant b (Table 1) had value characteristic of the surface structure of each adsorbent and was defined by the geometrical positions of reasonable chemi-sorptive sites on the predominant crystailographic surfaces. The chemisorptive sites seemed to be O2-for α-and β-FeOOH and OH- for γ-FeOOH. The effect of heat treatment of each FeOOH in vacuo on the NO adsorption was also examined and it was found that the samples prepared by calcinating any FeOOH at 500°C adsorbed considerably large amounts of NO (ca. 10~;15×l0″smmol/m2, see Figs. 3, 4, and 5). © 1979, The Chemical Society of Japan. All rights reserved.