Irreversible hydrogen uptake on Mo2N catalyst

Volumetric H-2-uptake measurements on an Mo2N (79 m(2)g(-1)) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308-623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature, The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The H-IR/Mo ratio calculated from the uptakes obtained in the temperature range of 308-623 K varies in the range of 0.0010-0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N pairs, in which the molybdenum atoms are in unsaturated coordination.