Slurry reaction system
The present invention provides a slurry reaction system wherein liquid reaction mixture containing catalyst fines is separated from catalyst particles of a size suitable for use in the slurry reaction in a first separation step and in a subsequent separation step the catalyst fines are separated from liquid reaction mixture.
1 . (canceled)
2 . A process for producing propylene oxide by reaction of propylene, oxygen and hydrogen in a slurry of catalyst particles having an average diameter of 30 to 40 micron and comprising a titanium or vanadium zeolite and a noble metal in a solvent, wherein a substantial portion of the catalyst particles are reduced in particle size by attrition to finer particles of less than 1 micron diameter, the improvement wherein in a first separation step catalyst particles of at least 5 micron diameter are separated from reaction liquid containing catalyst fines having less than 1 micron diameter, and in a subsequent separate separation the catalyst fines are filtered from reaction liquid.
3 . The process of claim 2 wherein said first separation step comprises an internal or external filtration and the liquid flow rate through the filtration is 0.01 to 2 gpm/sq.ft.
4 . The process of claim 2 wherein the filtration is operated at a differential pressure of 0 to 120 psia.
5 . The process of claim 2 wherein the catalyst particles comprise noble metal promoted titanium silicalite.
6 . The process of claim 2 wherein the solvent is methanol or methanol-water.