Oriented Isomorphous Substitution: An Efficient and Alternative Route to Fabricate the Zn Rich Phase Pure (Cu1-x,Zn-x)(2)(OH)(2)CO3 Precursor Catalyst for Methanol Synthesis

摘要

A new methodology has been demonstrated for the synthesis of a series of phase pure (Cu1-x,Zn-x)(2)(OH)(2)CO3 precursors by isomorphous substitution of Zn2+ in the malachite structure. By following the present protocol, it was possible to synthesize the pure phase (Cu1-x,Zn-x)(2)(OH)(2)CO3 with substitution level as high as x=0.5, which is better than the maximum possible value achieved by coprecipitation method, i. e. x=0.31. The isomorphous substitution by Zn2+ leads to the change in the morphology of malachite crystals from flake-like to regular needle-like shape with high Zn dispersion. The activity of the calcined catalysts was increased by similar to 1.5-1.7 fold for the hydrogenation of syngas to methanol as compared with those prepared from the traditional coprecipitation route. The synergy between Cu and ZnO was further demonstrated quantitatively by characterization of the catalysts treated with syngas at 250 degrees C.