文摘
The results of the study of phase formation, structural types, surface properties of the phosphates Cu0.5(1+y)FeyZr2−y(PO4)3 and their catalytic activity in methanol conversion are presented. The samples of phosphates with y = 0, 0.5, 1.0, 1.5 and 2.0 were prepared by the precipitating method. The X-ray phase analysis showed that the phosphates within 0 ≤ y ≤ 1.0 form a series of structural analogues belonging to the structural type of Sc2(WO4)3, the compound Cu1.5Fe2(PO4)3 (y = 2) crystallizes in the Fe7(PO4)6-type structure, the sample with y = 1.5 of the composition Cu1.25Fe1.5Zr0.5P3O12 was phase mixture. It was shown that with an increase in y value (i.e. with a reduction of the zirconium concentration in structures of phosphates) a reduction of a specific surface of samples (from 10 to 1.3 m2/g) and a progressive increase in surface acidity (from 5.2 to 14.7 μmol/m2) are observed. Catalytic properties of the phosphates in reactions of methanol conversion in argon inert and air oxidative atmospheres were studied. Methanol dehydration to dimethyl ether is observed in inert atmosphere only and on the iron-free phosphate (y = 0). Methanol dehydrogenation to formaldehyde takes place only in oxidative atmosphere, the degree of methanol conversion and formaldehyde selectivity depend on iron contents in the phosphate.
