SYNTHESIS OF THE Ni-CONTAINING PHOSPHATES WITH FRAMEWORK STRUCTURES AND THEIR CATALYTIC PROPERTIES IN THE CONVERSION OF METHANOL

Abstract

New phosphates Ca_0.5+xNi_xZr_2-x(PO₄)₃ (x=0.5, 1.0) and the phosphates B_0.5Zr₂(PO₄)₃(B=Ca,Ni) were prepared by the precipitating method. Phosphates were characterized using XRD, IR-spectroscopy and microprobe analysis. The specific surface areas of the samples were determined by the adsorption of nitrogen. It is shown that phosphates Ca_0.5+x?Ni_xZr_2-x(PO₄)₃ (x=0, 0.5, 1.0) were crystallized in the NaZr₂(PO₄)_3-type structure and the phosphate Ni_0.5Zr₂(PO₄)₃ was obtained as a single-phase with Sc₂(WO₄)_3-type structure. The conversion of methanol was studied in a convenient Ar-flow system, in the temperature range from 450 to 750 K. It is shown that the properties of the described phosphates as well as catalytic activity, selectivity, yields of products and alcohol conversion depend on the temperature, structure type, Ni-position in the framework of the phosphate or its cavities and the Ni content in the materials.