Alumina aerogel and process of preparing same

Claim 1

A STABLE AQUEOUS COLLOIDAL DISPERSION OF ALUMINA AERCGEL,WHICH DISPERSION IS FURTHER CHARACTERIZED IN THAT IT IS STABLE TOWARD APPRECIABLE SETTLING OF ALUMINA AEROGEL PARTICLES AT A CONCENTRATION OF 5% BY WEIGHT.

Claim 3

A METHOD OF PREPARING A WATER-DISPERSIBLE ALUMINA AEROGEL WHICH COMPRISES FORMING A HOMOGENEOUS SOLUTION OF AN AQUEOUS SOLUTION CONTAINING FROM 8 TO 31% BY WEIGHT OF ALUMINUM CHLORIDE AND AN AMOUNT OF LIQUID ETHYLENE OXIDE SUFFICIENT TO REACT WITH AT LEAST 90% OF SAID ALIUMINUM CHLORIDE BUT NOT IN EXCESS OF 4 MOLS OF ETHYLENE OXIDE PER MOL OF ALUMINUM CHLORIDE,AT A TEMPERATURE BELOW THE BOILING POINT OF LIQUID ETHYLENE OXIDE BUT ABOVE THE FREEZING POINT OF THE SOLUTION, ALLOWING THE RESULTING SOLUTION TO SET TO A GEL, WASHING THE RESULTING GEL, WHICH CONTAINS WATER, COLLOIDAL ALUMINA AND ETHYLENE CHLORHYDRIN, WITH A WATER-MISCIBLE MONOHYDRIN ALCOHOL HAVING A CRITICAL TEMPERATURE BELOW THE CRITICAL TEMPERATURE OF WATER UNTIL SUBSTANTIALLY ALL OF THE ETHYLENE CHLORHYDRIN IS REMOVED FROM THE GEL, HEATING THE GEL IN A PRESSURERESISTANT VESSEL UNTIL THE LIQUID IN THE GEL HAS REACHED A TEMPERATURE AT WHICH THE SURFACE TENSION OF THE LIQUID IS SO SMALL AS TO PRODUCE NO SUBSTANTIAL SHRINKAGE OF THE GEL WHEN THE LIQUID IS ALLOWED TO EVAPORATE, MAINTAINING SUCH TEMPERATURE, AND THEN RELEASING THE VAPOR FROM THE PRESSURE-RESISTANT VESSEL AT A RATE INSUFFICIENT TO INJURE THE GEL STRUCTURE.

Claim 4

A METHOD OF PREPARING A WATER-DISPERSIBLE ALUMINA AEROGEL WHICH COMPRISES FORMING A HOMOGENEOUS SOLUTION OF AN AQUEOUS SOLUTION CONTAINING FROM 8 TO 31% BY WEIGHT OF ALUMINUM CHLORIDE AND AN AMOUNT OF LIQUID ETHYLENE OXIDE SUFFICIENT TO REACT WITH AT LEAST 90% OF SAID ALIUMINUM CHLORIDE BUT NOT IN EXCESS OF 4 MOLS OF ETHYLENE OXIDE PER MOL OF ALUMINUM CHLORIDE,AT A TEMPERATURE BELOW THE BOILING POINT OF LIQUID ETHYLENE OXIDE BUT ABOVE THE FREEZING POINT OF THE SOLUTION, ALLOWING THE RESULTING SOLUTION TO SET TO A GEL, WASHING THE RESULTING GEL, WHICH CONTAINS WATER, COLLOIDAL ALUMINA AND ETHYLENE CHLORHYDRIN, WITH A WATER-MISCIBLE MONOHYDRIN ALCOHOL HAVING A CRITICAL TEMPERATURE BELOW THE CRITICAL TEMPERATURE OF WATER UNTIL SUBSTANTIALLY ALL OF THE ETHYLENE CHLORHYDRIN IS REMOVED FROM THE GEL, HEATING THE GEL IN A PRESSURERESISTANT VESSEL UNTIL THE LIQUID IN THE GEL HAS REACHED A TEMPERATURE AT WHICH THE SURFACE TENSION OF THE LIQUID IS SO SMALL AS TO PRODUCE NO SUBSTANTIAL SHRINKAGE OF THE GEL WHEN THE LIQUID IS ALLOWED TO EVAPORATE, MAINTAINING SUCH TEMPERATURE, AND THEN RELEASING THE VAPOR FROM THE PRESSURE-RESISTANT VESSEL AT A RATE INSUFFICIENT TO INJURE THE GEL STRUCTURE.