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Updated: Oct 3, 2026

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
Published on: February 19, 2018
Crystal Structure of an Ammonium Nickel Molybdate Prepared by Chemical Precipitation
Doron Levin1, Stuart L. Soled, Jackie Y. Ying
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Exxon Research and Engineering Company, Annandale, New Jersey 08801.
Abstract:
A layered ammonium nickel molybdate was prepared by precipitation from a solution of nickel nitrate and ammonium heptamolybdate. The compound obtained, (NH(4))HNi(2)(OH)(2)(MoO(4))(2), is trigonal with hexagonal unit cell parameters a = 6.0147(4) Å, c = 21.8812(13) Å, and Z = 3. A powder X-ray diffraction pattern was obtained using synchrotron radiation. The structure was generated from three-dimensional Patterson and difference Fourier density maps and refined in the space group R&thremacr;m by the Rietveld method. The structure consists of molybdate tetrahedra and nickel octahedra forming layers perpendicular to the c axis. There are three layers per unit cell, with ammonium ions incorporated between the layers. The structure is a member of a solid solution series of (NH(4))H(2)(x)()Ni(3)(-)(x)()O(OH)(MoO(4))(2), where 0 = x = (3)/(2). The nonstoichiometry arises from variable occupancy of the nickel position and allows for the formation of these compounds having Ni/Mo ratios varying from 0.75 to 1.5.
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