Preparation of amorphous alumina spheres

Claim 1

A METHOD OF PREPARING AMORPHOUS, HIGH SURFACE AREA ALUMINA SPHERES, WHICH COMPRISES: A. COMMINGLING AN AMMONIA PRECURSOR AND AN ACIDIC ALUMINA HYDDROSOL AT BELOW GELATIONN TEMPERATURE, SAID AMMONIA PRECURSOR BEING DECOMPOSABLE TO AMMONIAWITH INCREASING TEMPERATURE; B. DISPERSING THE MIXTURE AS DROPLETS IN A HOT OIL BATH EFFECTING DECOMPOSITION OF SAID AMMONIA PRECURSOR AND FORMATION OF HYDROGEL SPHERES THEREIN; C. SEPARATING AND IMMERSINNG THE HYDROGEL PARTICLES IN AN AQUEOUS AMMONONIIUM CHLORIDE SALT SOLUTION HAVING A PH OF AT LEAST ABOUT 5.5, AND HAVING A SALT CONCENTRATION SUBSTANTIALLY EQUIVALENT TO THE SALT CONCENTRATION OF THE INTERNAL AQUEOUS PHASE OF SAID HYDROGEL PARTICLES; D. MAINTIAINING SAD PARTICLES IN CONTACT WITH SAID SOLUTION WHILE REDUCING THE SALT CONCENTRATION GRADUALLY AT CONDITIONS TO MINIMIZE THE CONCENTRATION GRADIENT BETWEEN SAID SOLUTION AND THE INTERNAL AQUEOUS PHASE OF SAID PARTICLES, UNTIL SAID SOLUTION ISSUBSTANTIALLY SALT-FREE; E. SEPARATING, AND DRYING AND CALCINING THE RESULTING SALT-FREE HYDROGEL PARTICLES.

Claim 2

A METHOD OF PREPARING AMORPHOUS, HIGH SURFACE AREA ALUMINA SPHERES, WHICH COMPRISES: A. COMMINGLING AN AMMONIA PRECURSOR AND AN ACIDIC ALUMINA HYDDROSOL AT BELOW GELATIONN TEMPERATURE, SAID AMMONIA PRECURSOR BEING DECOMPOSABLE TO AMMONIAWITH INCREASING TEMPERATURE; B. DISPERSING THE MIXTURE AS DROPLETS IN A HOT OIL BATH EFFECTING DECOMPOSITION OF SAID AMMONIA PRECURSOR AND FORMATION OF HYDROGEL SPHERES THEREIN; C. SEPARATING AND IMMERSINNG THE HYDROGEL PARTICLES IN AN AQUEOUS AMMONONIIUM CHLORIDE SALT SOLUTION HAVING A PH OF AT LEAST ABOUT 5.5, AND HAVING A SALT CONCENTRATION SUBSTANTIALLY EQUIVALENT TO THE SALT CONCENTRATION OF THE INTERNAL AQUEOUS PHASE OF SAID HYDROGEL PARTICLES; D. MAINTIAINING SAD PARTICLES IN CONTACT WITH SAID SOLUTION WHILE REDUCING THE SALT CONCENTRATION GRADUALLY AT CONDITIONS TO MINIMIZE THE CONCENTRATION GRADIENT BETWEEN SAID SOLUTION AND THE INTERNAL AQUEOUS PHASE OF SAID PARTICLES, UNTIL SAID SOLUTION ISSUBSTANTIALLY SALT-FREE; E. SEPARATING, AND DRYING AND CALCINING THE RESULTING SALT-FREE HYDROGEL PARTICLES.

Claim 3

A method of preparing amorphous, high surface area alumina spheres, which comprises: a. commingling an ammonia precursor and an acidic alumina hydrosol at below gelation temperature, said ammonia precursor being decomposable to ammonia with increasing temperature; b. dispersing the mixture as droplets in a hot oil bath effecting decomposition of said ammonia precursor and formation of hydrogel spheres therein; c. separating and immersing the hydrogel particles in an aqueous ammonium chloride salt solution having a pH of at least about 5.5, and having a salt concentration substantially equivalent to the salt concentration of the internal aqueous phase of said hydrogel particles; d. maintaining said particles in contact with said solution while reducing the salt concentration gradually at conditions to minimize the concentration gradient between said solution and the internal aqueous phase of said particles, until said solution is substantially salt-free; e. separating, and drying and calCining the resulting salt-free hydrogel particles.

Claim 4

A method of preparing amorphous, high surface area alumina spheres, which comprises: a. commingling an ammonia precursor and an acidic alumina hydrosol at below gelation temperature, said ammonia precursor being decomposable to ammonia with increasing temperature; b. dispersing the mixture as droplets in a hot oil bath effecting decomposition of said ammonia precursor and formation of hydrogel spheres therein; c. separating and immersing the hydrogel particles in an aqueous ammonium chloride salt solution having a pH of at least about 5.5, and having a salt concentration substantially equivalent to the salt concentration of the internal aqueous phase of said hydrogel particles; d. maintaining said particles in contact with said solution while reducing the salt concentration gradually at conditions to minimize the concentration gradient between said solution and the internal aqueous phase of said particles, until said solution is substantially salt-free; e. separating, and drying and calCining the resulting salt-free hydrogel particles.