Scientific bases for the synthesis of highly dispersed framework zirconium phosphate catalysts for paraffin isomerization and selective oxidation

Results of the systematic study of the synthesis of highly dispersed framework zirconium phosphates stabilized by ammonium, lanthanum, aluminum, manganese, and cobalt cations were presented. The synthesis involved the mechanochemical activation of a mixture of solid reactants (salts) or the sol-gel process each followed by the hydrothermal treatment of obtained precursors in the presence of surfactants. The relationship between the bulk structure parameters of framework zirconium phosphates, which are controlled by varying the chemical composition and conditions of synthesis, and the surface characteristics of the systems (the strength and concentration of different Lewis and Brønsted sites) was studied. The introduction of silicon into framework zirconium phosphates and the modification of their surface with tungsten and platinum, increased the stead-state conversion (to 30-40%) at 250°-350°C with retention of a high (about 80%) selectivity with respect to isomers. The systems based on framework zirconium phosphates are promising catalysts for paraffin (pentane and hexane) isomerization, the selective oxidation of methane by oxygen into synthesis gas at short contact times, and the oxidative dehydrogenation of propane into propylene.