Method for producing alpha-alumina formed body

Abstract

A high-strength α-alumina formed body with a low soda content, of which pore distribution is controlled, can be provided in an easy and inexpensive manner. The α-alumina formed body can be produced by a method comprising calcining a gibbsite-phase aluminum hydroxide to obtain rehydratable alumina powder; forming the rehydratable alumina powder in the presence of water to obtain a formed body; maintaining the formed body in the presence of water at about 110-200 ° C., to rehydrate the formed body; and calcining the rehydrated formed body at about 1200° C. or higher. The α-alumina formed body is useful as a carrier for catalysts, chemicals, microbes for food leftover disposal and the like.

What is claimed is:  
     
         1 . A method for producing an α-alumina formed body, the method comprising the steps of: 
 (i) calcining a gibbsite-phase aluminum hydroxide controlled in median particle size and in packed bulk density to obtain at least partially rehydratable alumina powder;  
 (ii) forming the at least partially rehydratable alumina powder in the presence of water to obtain a formed body;  
 (iii) maintaining the formed body in the presence of water at a temperature of form about 110° C. to about 200° C., to rehydrate the formed body; and  
 (iv) calcining the rehydrated formed body at a temperature of about 1200° C. or higher.  
 
     
     
         2 . A method for producing an α-alumina formed body according to  claim 1 , which further comprising a step of washing the rehydrated α-alumina formed body with water at a temperature of 100° C. or lower before the calcining thereof.  
     
     
         3 . A method for producing an α-alumina formed body according to  claim 1  or  2 , wherein the gibbsite-phase aluminum hydroxide has a median particle size of about 15 μm or smaller.  
     
     
         4 . A method for producing an α-alumina formed body according to  claim 1  or  2 , wherein the gibbsite-crystal aluminum hydroxide has a packed bulk density of about 0.8 g/cm 3  or larger.  
     
     
         5 . A carrier for supporting catalysts, chemicals or microbes for food leftover disposal, which comprises the α-alumina formed body obtained by a method according to  claim 1 .  
     
     
         6 . A method for using the α-alumina formed body obtained by a method according to  claim 1  as a carrier.