Chemisorption of nitric oxide on char. 1. Reversible nitric oxide sorption

The process of chemisorption of nitric oxide (NO) on a carbon derived from phenol-formaldehyde resin has been studied at temperatures between 323 and 473 K and at NO partial pressures between 2.02 and 10.1 kPa. The process of chemisorption can be split into two separate pathways-one a reversible chemisorptive pathway forming nitric oxide surface complexes C(NO) and the other an irreversible chemisorptive pathway yielding N[sub 2] and carbon surface oxides C(O) and C(O[sub 2]). The enthalpy of formation of C(NO) is between 42 and 46 kJ/mol exothermic. The reversible pathway is governed by isotherms that are linear in NO partial pressure, within the range of pressures studied here. This same process, however, appears to be kinetically second order with respect to NO partial pressure, suggesting a possible role of NO dimer as an intermediate in the process. 35 refs., 11 figs., 1 tab.