INFLUENCE OF CONDITIONS OF ALUMINUM HYDROXIDE THERMOCHEMICAL ACTIVATION ON PHASE-COMPOSITION AND CRYSTALLINITY OF THE SUPPORT OBTAINED

The phase composition and crystallinity of aluminum hydroxides prepare d by thermal. decomposition of hydrargillite with subsequent treatment in an autoclave at 130 - 180 degrees C for 5 - 20 h in the presence o f nitric acid are studied by IR spectroscopy, thermogravimetry, and X- ray analysis. It is shown that a variation in temperature and time of autoclave treatment permits one to regulate the number and the size of boehmite crystals obtained. Mechanical grinding of the samples before the autoclave treatment and a decrease in the temperature of the proc ess to 130 - 135 degrees C allows one to prepare a support that is ide ntical in the phase composition to the commercial alumina prepared by precipitation.