Process for direct oxidation of propylene to propylene oxide and large particle size titanium silicalite catalysts for use therein

1. A continuous process for the epoxidation of olefins, said process comprising:

a) providing a reactor containing a titanium silicalite epoxidation catalyst, said titanium silicalite being in the form of crystals or crystal intergrowths, said crystals or crystal intergrowths having a mean particle size of greater than 2 μm;

b) continuously supplying olefin to said reactor;

c) supplying hydrogen and oxygen to said reactor, optionally together with hydrogen peroxide, whereby at least a portion of said olefin is epoxidized to an alkylene oxide; and

d) continuously removing said olefin oxide, and isolating said olefin oxide, wherein the reactor further contains a noble metal catalyst.

2. The process of claim 1 , wherein said olefin is an α-olefin.

3. The process of claim 1 , wherein said olefin is propylene.

4. The process of claim 1 , wherein at least a portion of said titanium silicalite epoxidation catalyst is treated to contain a noble metal which is effective to catalyze formation of hydrogen peroxide from hydrogen and oxygen.

5. The process of claim 2 , wherein said noble metal is selected from the group consisting of palladium, gold, platinum, and mixtures thereof.

6. The process of claim 4 , wherein a noble metal treated particulate other than a titanium silicalite crystal or crystal intergrowth is further provided to said reactor.

7. The process of claim 1 , wherein said titanium silicalite catalyst comprises intergrowths of titanium silicalite crystals.

8. The process of claim 1 , wherein said titanium silicalite is prepared from a hydrolyzable silica source containing less than 500 ppm alkali metal.

9. A process for the continuous production of olefin oxides, said process comprising:

a) providing a slurry reactor containing titanium silicalite particles having a mean diameter greater than 2 μm as a dispersed phase in a liquid continuous phase;

b) introducing into said slurry reactor an epoxidizing oxygen source comprising hydrogen and oxygen;

c) introducing into said reactor at least one olefin;

d) withdrawing a product stream comprising liquid continuous phase, olefin oxide, and olefin oxide equivalents;

e) separating any entrained catalyst particles from said product stream prior to, during, or after separation of olefin oxide from said product stream;

f) separating said olefin oxide from said product stream to provide an olefin oxide product;

wherein a noble metal catalyst is further present.

10. The process of claim 9 , wherein said noble metal comprises one or more of Pd, Au, or Pt.

11. The process of claim 9 , wherein said titanium silicalite particles are titanium silicalite intergrowths having a mean particle size of from 3 μm to 30 μm.

12. The process of claim 9 , wherein said noble metal is contained in or on said titanium silicalite catalyst.

13. The process of claim 9 , further comprising separating at least a portion of said liquid continuous phase from said product stream and recycling said at least a portion of said liquid continuous phase to the reactor as a make-up solvent stream.

14. The process of claim 9 , wherein said liquid continuous phase comprises water, methanol, or a mixture of water and methanol.

15. The process of claim 9 , wherein an alkali or metal or ammonium carbonate or bicarbonate are additionally introduced into said reactor.

16. The process of claim 9 , wherein said olefin comprises propylene.

17. The process of claim 9 , wherein said noble metal comprises palladium, gold, or platinum, or mixtures thereof.

18. The process of claim 9 , wherein an ammonium phosphate or ammonium hydrogen phosphate or mixture thereof are introduced into said reactor.