Process for the preparation of propylene oxide

Patent metadata

Field	Value
Publication number	US-10544115-B2
Application number	US-201716076600-A
Country	US
Kind code	B2
Filing date	Feb 16, 2017
Priority date	Feb 17, 2016
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

A continuous process for the preparation of propylene oxide, comprising a start-up stage and normal run stage, wherein the normal run stage comprises (i) continuously providing a liquid feed stream comprising propene, hydrogen peroxide, acetonitrile, a formate salt, water and optionally propane, wherein in the liquid feed stream, the molar amount of the formate salt relative to the molar amount of hydrogen peroxide at a given point of time during the normal run stage is aN(Fo/H2O2); (ii) continuously passing the liquid feed stream provided in (i) into an epoxidation zone comprising a catalyst comprising a titanium zeolite having framework type MWW, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation zone, obtaining a reaction mixture comprising propylene oxide, acetonitrile, water, the formate salt, optionally propene, and optionally propane; (iii) continuously removing an effluent stream from the epoxidation zone, the effluent stream comprising propylene oxide, acetonitrile, water, at least a portion of the formate salt, optionally propene, and optionally propane; wherein the normal run stage is characterized in an average rate of change of aN(Fo/H2O2) of less than 0 h−1.

First claim

The invention claimed is:

1. A continuous process for preparing propylene oxide comprising a start-up stage and a normal run stage, wherein the normal run stage comprises:
(i) continuously providing a liquid feed stream comprising propene, hydrogen peroxide, acetonitrile, a formate salt, water and optionally propane, wherein in the liquid feed stream, the molar amount of the formate salt relative to the molar amount of hydrogen peroxide at a given point of time during the normal run stage is a N (Fo/H 2 O 2 );
(ii) continuously passing the liquid feed stream provided in (i) into an epoxidation zone comprising a catalyst comprising a titanium zeolite having framework MWW, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation zone, obtaining a reaction mixture comprising propylene oxide, acetonitrile, water, the formate salt, optionally propene, and optionally propane; and
(iii) continuously removing an effluent stream from the epoxidation zone, the effluent stream comprising propylene oxide, acetonitrile, water, at least a portion of the formate salt, optionally propene, and optionally propane;
wherein the normal run stage is characterized in an average rate of change of a N (Fo/H 2 O 2 ) of less than 0 h −1 .

2. The continuous process of claim 1 , wherein the average rate of change of a N (Fo/H 2 O 2 ) ranges from −10 −10 to −10 −6 h −1 .

3. The continuous process of claim 1 , wherein at the beginning of the normal run stage, a N (Fo/H 2 O 2 ) ranges from 1.0*10 −4 to 1.0*10 −2 .

4. The continuous process of claim 1 , wherein:
during the normal run stage, the epoxidation conditions according to (ii) comprise an epoxidation temperature T N ;
during the normal run stage, the average rate of change of T N ranges from 0 to 50 K*h −1 ; and
T N is the temperature of a heat transfer medium used for adjusting the temperature of the reaction mixture in the epoxidation reaction zone according to (ii).

5. The continuous process of claim 4 , wherein:
during the initial stage of the normal run stage, the average rate of change of T N ranges from 0 to 0.5 K*h −1 ; and
after said initial stage, when a N (Fo/H 2 O 2 ) ranges from 40 to 60% of a N (Fo/H 2 O 2 ) at the beginning of the normal run stage, T N is increased by at least 0.1° C.

6. The continuous process of claim 4 , wherein during the normal run stage, T N ranges from 20 to 70° C.

7. The continuous process of claim 1 , wherein:
during the normal run stage, the epoxidation conditions according to (ii) comprise a hydrogen peroxide conversion c N (H 2 O 2 );
the average rate of change of c N (H 2 O 2 ) ranges from −1.0*10 −3 to 1.0*10 −3 %-points*h −1 ; and
c N (H 2 O 2 ) is defined as the molar amount of hydrogen peroxide comprised in the effluent stream removed in (iii) relative to the molar amount of hydrogen peroxide comprised in the liquid feed stream provided in (i) at a given point of time during the normal run stage.

8. The continuous process of claim 7 , wherein during the normal run stage, c N (H 2 O 2 ) ranges from 99.5 to 100%.

9. The continuous process of claim 1 , wherein the formate salt according to (i) consists of a potassium formate salt.

10. The continuous process of claim 1 , wherein:
during the normal run stage, the epoxidation conditions according to (ii) comprise an epoxidation reaction pressure ranging from 14 to 100 bar; and
the epoxidation reaction pressure is defined as the absolute pressure at the exit of the epoxidation zone.

11. The continuous process of claim 1 , wherein:
during the normal nm stage, the epoxidation conditions according to (ii) comprise a catalyst loading ranging from 0.05 to 1.25 h −1 ; and
the catalyst loading is defined as the ratio of the mass flow rate in kg/h of hydrogen peroxide contained in liquid feed stream provided in (i) relative to the amount in kg of catalyst comprising a titanium zeolite having framework MWW comprised in the epoxidation zone according to (ii).

12. The continuous process of claim 1 , wherein the titanium zeolite having framework MWW comprised in the catalyst according to (ii) contains titanium, calculated as elemental titanium, in an amount ranging from 0.1 to 5 weight-%, based on the total weight of the titanium zeolite having framework MWW.

13. The continuous process of claim 1 , wherein the titanium zeolite having framework MWW comprised in the catalyst according to (ii) contains titanium, calculated as elemental titanium, in an amount ranges from 0.1 to 5 weight-%, based on the total weight of the titanium zeolite having framework MWW, and contains zinc, calculated as elemental zinc, in an amount ranging from 0.1 to 5 weight-%, based on the total weight of the titanium zeolite having framework MWW.

14. The continuous process of claim 1 , wherein during the normal run stage, the liquid feed stream provided in (i) comprises:
the acetonitrile in an amount ranging from 60 to 75 weight-%, based on the total weight of the liquid feed stream;
the hydrogen peroxide in an amount ranging from 6 to 10 weight-%, based on the total weight of the liquid feed stream;
the water at a molar ratio of water relative to acetonitrile ranging from 1:50 to 1:4;
the propene at a molar ratio of propene relative to hydrogen peroxide comprised in the liquid feed stream ranging from 1:1 to 1.6:1, and
optionally the propane at a molar ratio of propane relative to the sum of propene and propane ranging from 0.0001:1 to 0.15:1;
wherein at least 95 weight-% of the liquid feed stream provided in (i) consist of propene, hydrogen peroxide, acetonitrile, the formate salt, water and optionally propane.

15. The continuous process of claim 1 , comprising a start-up stage prior to the normal run stage, wherein the start-up stage comprises:
(a) continuously providing a liquid feed stream comprising propene, acetonitrile, and optionally propane and continuously passing said liquid feed stream under start-up conditions for a period of time t 1 into the epoxidation zone comprising the catalyst comprising a titanium zeolite having framework MWW;
wherein after the period of time t 1 , the start-up stage further comprises:

(b) continuously providing a liquid feed stream comprising hydrogen peroxide, admixing said liquid feed stream to the liquid feed stream provided in (a) obtaining a liquid feed stream comprising hydrogen peroxide, propene, acetonitrile, and optionally propane, and continuously passing said liquid feed stream under start-up conditions for a period of time t 2 into the epoxidation zone comprising the catalyst comprising a titanium zeolite having framework structure MWW,
wherein:
the liquid feed stream according to (b) comprises the formate salt, wherein the molar amount of the formate salt relative to the molar amount of hydrogen peroxide at a given point of time during step (b) of the start-up stage is a S (Fo/H 2 O 2 ); and
after the period of time t 2 , the normal run stage begins and a S (Fo/H 2 O 2 ) is a N (Fo/H 2 O 2 ) at the beginning of the normal run stage.

16. The continuous process of claim 15 , wherein at least 98 weight-% of the liquid feed stream provided in (a) consist of propene, acetonitrile, and optionally propane, wherein the liquid feed stream according to (a) comprises hydrogen peroxide in an amount ranging from 0 to 0.01 weight-%, based on the total weight of the liquid feed stream, and wherein the liquid feed stream according to (a) comprises the formate salt in an amount ranging from 0 to 0.01 weight-%, based on the total weight of the liquid feed stream.

17. The continuous proc

Assignees

• Basf Se

Inventors

• Riedel Dominic
• Teles Joaquim Henrique
• Schelling Heiner
• Wegerle Ulrike
• Mueller Ulrich
• Parvulescu Andrei-Nicolae
• Mannweiler Jochen
• Henn Timo
• Luederitz Thomas
• Woerz Nicolai Tonio
• Mueller Christian
• Weber Markus
• Urbanczyk Daniel

Classifications

• C07D301/12 Primary

  with hydrogen peroxide or inorganic peroxides or peracids · CPC title

• C07D301/36

  Use of additives, e.g. for stabilisation · CPC title

• B01J29/7088

  MWW-type, e.g. MCM-22, ERB-1, ITQ-1, PSH-3 or SSZ-25 · CPC title

• B01J19/0013

  Controlling the temperature of the process · CPC title

• B01J2219/00162

  controlling the pressure · CPC title