Hydrogen reduction of nickel ions in molecular sieve X

Abstract

The hydrogen reduction of nickel ions in a microcrystalline sample of molecular sieve X has been studied in the temperature range 620–790 K at pressures from 0.03 to 13 kN m^–2. A mechanism involving a back reaction between product nickel atoms and zeolitic water is proposed which accounts for the experimental data and gives the fraction of nickel ions at site II. Although this fraction decreases somewhat with increasing nickel ion exchange, there appears to be no marked site preference shown by nickel ions exchanging into NaX.