Process for preparing aggregates

Abstract

Hard, rounded aggregates are produced by preparing droplets of a slurry consisting of suspending liquid containing distinct particles of a solid and dropping the droplets of the slurry onto a bed of particles under conditions where the suspending liquid of the slurry droplet is removed. This technique is especially desirable for making unique fixed-bed catalysts.

We claim: 
     
       1. A process for preparing aggregates comprising (a) preparing a slurry, said slurry comprising a suspending liquid and distinct particles of a first solid suspended in said liquid;   (b) preparing a particle bed consisting of particles of a second solid;   (c) forming droplets of said slurry; and   (d) dropping said droplets of said slurry into said particle bed .Iadd.in such a manner that the total droplet is not immersed in the powder and .Iaddend.under conditions where said suspending liquid is at least partially removed from the slurry droplet to form an aggregate of said distinct particles of said first solid .Iadd.having a void center. .Iaddend.   
     
     
       2. The process of claim 1 wherein said suspending liquid is water. 
     
     
       3. The process of claim 1 wherein the first solid is a catalyst or a catalyst precursor. 
     
     
       4. The process of claim 1 wherein the first solid contains at least bismuth and molybdenum. 
     
     
       5. The process of claim 1 wherein the particle size of the first solid is less than about a millimeter. 
     
     
       6. The process of claim 1 wherein the slurry has an apparent viscosity of about 400 to about 15,000 centipoise. 
     
     
       7. The process of claim 1 wherein the particle bed is composed of particles having a size of below about 500 microns. 
     
     
       8. The process of claim 1 wherein the first solid and said second solid are chemically similar.  .[.9. The process of claim 1 whereby an aggregate with a void center is produced..]. .Iadd. 10. The process in claim 1 wherein the particle bed is static when receiving said droplets. .Iaddend.