PROCESS FOR THE EPOXIDATION OF PROPENE TO PROPYLENE OXIDE

Abstract

A continuous process for the preparation of propylene oxide, comprising providing a liquid feed stream comprising propene, hydrogen peroxide, methanol, water, at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane; passing the liquid feed stream provided in (i) into an epoxidation reactor comprising a catalyst comprising a titanium zeolite of structure type MFI, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation reactor, obtaining a reaction mixture comprising propylene oxide, methanol, water, and the at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane; removing an effluent stream from the epoxidation reactor, the effluent stream comprising propylene oxide, methanol, water, at least a portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane.

Claims

1. A continuous process for preparing propylene oxide, the process comprising: (i) passing a liquid feed stream, comprising propene, hydrogen peroxide, methanol, water, at least one dissolved potassium salt of hydroxyethylidene diphosphonic acid, and optionally propane, into an epoxidation reactor comprising a catalyst comprising a titanium zeolite of structure type MFI, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation reactor, to obtain a reaction mixture comprising propylene oxide, methanol, water, and the at least one dissolved potassium salt of hydroxyethylidene diphosphonic acid, and optionally propane; and (ii) removing an effluent stream from the epoxidation reactor, the effluent stream comprising propylene oxide, methanol, water, at least a portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane.

2. The process of claim 1, wherein the molar ratio of potassium relative to phosphorus in the at least one potassium salt of hydroxyethylidene diphosphonic acid ranges from 1:2 to 2:1.

3. The process of claim 1, wherein the at least one potassium salt of hydroxyethylidenediphosphonic acid comprises a dipotassium salt of hydroxyethylidenediphosphonic acid.

4. The process of claim 1, wherein: in the liquid feed stream, the molar ratio of potassium comprised in the at least one potassium salt of hydroxyethylidenediphosphonic acid relative to the hydrogen peroxide ranges from 510.sup.6:1 to 100010.sup.6:1; and, in the liquid feed stream, the molar ratio of potassium in the liquid feed stream relative to the potassium comprised in the at least one potassium salt of hydroxyethylidenediphosphonic acid ranges from 1.2:1 to 1:1.

5. The process of claim 1, wherein, in the liquid feed stream, the molar ratio of phosphorus in the liquid feed stream relative to phosphorus comprised in the at least one potassium salt of hydroxyethylidenediphosphonic acid ranges from 1.2:1 to 1:1.

6. The process of claim 1, wherein: the liquid feed stream passed into the epoxidation reactor has a temperature ranging from 0 to 60 C.; and the liquid feed stream passed into the epoxidation reactor is at a pressure ranging from 14 to 100 bar.

7. The process of claim 1, wherein: the temperature of the reaction mixture is controlled using a heat transfer medium; the epoxidation reaction conditions comprise an epoxidation reaction temperature ranging from 10 to 100 C., wherein the epoxidation reaction temperature is defined as the temperature of the heat transfer medium prior to controlling of the temperature of the reaction mixture; and, the epoxidation reaction conditions comprise an epoxidation reaction pressure ranges from 14 to 100 bar, wherein the epoxidation reaction pressure is defined as the pressure at the exit of the epoxidation reactor.

8. The process of claim 1, wherein: the effluent stream further comprises hydrogen peroxide and optionally propene; and the process further comprises: (iii) separating propylene oxide from the effluent stream, obtaining a stream being depleted in propylene oxide and comprising hydrogen peroxide, methanol, water, at least a portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, optionally propene and optionally propane; (iv) passing the stream being depleted in propylene oxide and comprising hydrogen peroxide, methanol, water, at least a portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, optionally propene and optionally propane, obtained in (iii) into an epoxidation reactor comprising a catalyst comprising a titanium zeolite of structure type MFI, and subjecting the stream to epoxidation reaction conditions in the epoxidation reactor, to obtain a reaction mixture comprising propylene oxide, methanol, water, the portion of the at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane; and (v) removing an effluent stream from the epoxidation reactor of (iv), the effluent stream comprising propylene oxide, methanol, water, at least a portion of the portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane.

9. The process of claim 1, wherein the epoxidation reaction conditions comprise a hydrogen peroxide conversion ranging from 90 to 100%, wherein the hydrogen peroxide conversion is calculated based on the amount of hydrogen peroxide comprised in the effluent stream removed in (ii), relative to the amount of hydrogen peroxide comprised in the liquid feed stream in (i).

10. The process of claim 1, wherein: the catalyst comprising a titanium zeolite of structure type MFI is present in the reactor as fixed-bed catalyst; and the titanium zeolite of structure type MFI comprises titanium silicalite-1.

11. The process of claim 1, wherein: the oxygen selectivity of the epoxidation reaction is at most 1.2%, wherein the oxygen selectivity is defined as the molar amount of oxygen comprised in the effluent stream removed in (ii), relative to the molar amount of hydrogen peroxide comprised in the liquid feed stream; and the organic by-product selectivity of the epoxidation reaction is at most 9.0%, wherein the organic by-product selectivity is defined as the molar amount of hydrogen peroxide consumed to produce the molar amount of organic by-products comprised in the effluent stream removed in (ii), relative to the total molar amount of hydrogen peroxide consumed.

12. A catalytic system, comprising a catalyst comprising a titanium zeolite of structure type MFI and at least one potassium salt of hydroxyethylidene diphosphonic acid, wherein the titanium zeolite of structure type MFI comprises titanium silicalite-1.

13. The catalytic system of claim 12, wherein the molar ratio of potassium relative to phosphorus in the at least one potassium salt of hydroxyethylidenediphosphonic acid ranges from 1:2 to 2:1.

14. The catalytic system of claim 12, wherein the at least one potassium salt of hydroxyethylidenediphosphonic acid is a dipotassium salt of hydroxyethylidene-diphosphonic acid.

15. The catalyst system of claim 12, which is adapted to function as a catalyst system for the epoxidation of propene.

Description

SHORT DESCRIPTION OF THE FIGURES

[0250] FIG. 1 shows, on the Y axis, the selectivity of 2-methoxy-1-propanol (solid circles: K.sub.2HPO.sub.4, rectangles: K.sub.2HEDP as buffer). The x axis shows the run time in h.

[0251] FIG. 2 shows, on the Y axis, the H.sub.2O.sub.2-based selectivity to PO (solid circles: K.sub.2HPO.sub.4, rectangles: K.sub.2HEDP as buffer). The x axis shows the run time in h.

[0252] FIG. 3 shows, on the Y axis, the oxygen selectivity (solid circles: K.sub.2HPO.sub.4, rectangles: K.sub.2HEDP as buffer). The x axis shows the run time in h.

[0253] FIG. 4 shows, on the Y axis, the cooling water temperature (solid circles: K.sub.2HPO.sub.4, rectangles: K.sub.2HEDP as buffer). The x axis shows the run time in h.

[0254] FIG. 5 shows, on the Y axis, the H.sub.2O.sub.2 conversion (solid circles: K.sub.2HPO.sub.4, rectangles: K.sub.2HEDP as buffer). The x axis shows the run time in h.

[0255] FIG. 6 shows, on the Y axis, the selectivity of 2-methoxy-1-propanol. The x axis shows the run time in h.

[0256] FIG. 7 shows, on the Y axis, the H.sub.2O.sub.2-based selectivity to PO. The x axis shows the run time in h.

[0257] FIG. 8 shows, on the Y axis, the oxygen selectivity. The x axis shows the run time in h.

[0258] FIG. 9 shows, on the Y axis, the cooling water temperature. The x axis shows the run time in h.

[0259] FIG. 10 shows, on the Y axis, the H.sub.2O.sub.2 conversion. The x axis shows the run time in h.

[0260] FIG. 11 shows, on the Y axis, the selectivity of 2-methoxy-1-propanol from Comparative Example 2 (rectangles: K-ATMP as buffer, triangles: K.sub.2-ATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0261] FIG. 12 shows, on the Y axis, the selectivity of 1-methoxy-2-propanol from Comparative Example 2 (rectangles: K-ATMP as buffer, triangles: K.sub.2-ATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0262] FIG. 13 shows, on the Y axis, the H.sub.2O.sub.2-based selectivity to PO from Comparative Example 2 (rectangles: K-ATMP as buffer, triangles: K.sub.2-ATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0263] FIG. 14 shows, on the Y axis, the selectivity of 2-methoxy-1-propanol from Example 1, Comparative Example 1 and Comparative Example 3 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0264] FIG. 15 shows, on the Y axis, the selectivity to oxygen from Example 1, Comparative Example 1 and Comparative Example 3 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0265] FIG. 16 shows, on the Y axis, the H.sub.2O.sub.2-based selectivity to PO from Example 1, Comparative Example 1 and Comparative Example 3 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0266] FIG. 17 shows, on the Y axis, the selectivity of 2-methoxy-1-propanol from Example 1, Comparative Example 1 and Comparative Examples 3 and 4 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer, triangles: [NH.sub.4].sub.xATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0267] FIG. 18 shows, on the Y axis, the selectivity of 1-methoxy-2-propanol from Example 1, Comparative Example 1 and Comparative Examples 3 and 4 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer, triangles: [NH.sub.4].sub.xATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0268] FIG. 19 shows, on the Y axis, the selectivity to oxygen from Example 1, Comparative Example 1 and Comparative Examples 3 and 4 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer, triangles: [NH.sub.4].sub.xATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

[0269] FIG. 20 shows, on the Y axis, the H.sub.2O.sub.2-based selectivity to PO from Example 1, Comparative Example 1 and Comparative Examples 3 and 4 (solid circles: K.sub.2HPO.sub.4, crosses: K.sub.2HEDP, rectangles: NH.sub.4HEDP as buffer, triangles: [NH.sub.4].sub.xATMP as buffer). The x axis shows the run time in h (HOS, hours on stream).

CITED LITERATURE

[0270] U.S. Pat. No. 4,833,260

[0271] U.S. Pat. No. 4,824,976

[0272] EP 0 757 045 A