Integrated process for making propene and propene oxide from propane
The integrated process comprises a step a) of dehydrogenating propane providing a stream S1 comprising propane and propene; a step b) of separating stream S1 in at least one rectification column, providing an overhead product stream S2 comprising more than 99% by weight propene, a side stream S3 comprising from 90 to 98% by weight propene and a bottoms product stream S4 enriched in propane; a step c) of reacting propene with hydrogen peroxide in the presence of an epoxidation catalyst using propene in molar excess; and a step d) of separating non-reacted propene and propene oxide from the reaction mixture of step c) providing a propene oxide product and a stream S5 comprising propene and propane; wherein stream S3 is passed to step c), stream S5 is recycled to step b) and stream S4 is recycled to step a).
1. An integrated process for making propene and propene oxide from propane, comprising:
a) a step of dehydrogenating propane to provide a stream, S1, comprising propane and propene, wherein the combined amount of propane and propene in stream S1 is at least 95% by weight;
b) a step of separating stream S1 in at least one rectification column to provide:
i) an overhead product stream, S2, comprising more than 99% by weight propene;
ii) a side stream, S3, comprising from 90 to 98% by weight propene; and
iii) a bottoms product stream, S4, enriched in propane relative to stream S1;
c) a step of reacting propene with hydrogen peroxide in the presence of an epoxidation catalyst using propene in molar excess to hydrogen peroxide, to provide a reaction mixture comprising propene oxide and non-reacted propene; and
d) a step of separating non-reacted propene and propene oxide from the reaction mixture of step c) to provide a propene oxide product and a stream, S5, comprising propene and propane;
wherein: stream S3 is passed to step c); stream S5 is recycled to the rectification column of step b); and stream S4 is recycled to step a).
2. The process of claim 1 , wherein step b) is carried out in a single rectification column.
3. The process of claim 1 , wherein:
step b) is carried out in two thermally integrated rectification columns, wherein the first column is operated at a higher pressure than the second column, and overhead vapor from the first column is used for heating the bottoms evaporator of the second column;
streams S1 and S5 are fed to the first column;
side stream S3 is withdrawn from the first column;
the bottoms product of the first column is the feed to the second column;
the bottoms product of the second column is withdrawn as stream S4; and
the overhead products of the first and second column are combined to provide stream S2.
4. The process of claim 3 , wherein side stream S3 is withdrawn as a vapor stream and used for heating the bottoms evaporator of the second column.
5. The process of claim 1 , wherein stream S4 comprises more than 90% by weight propane.
6. The process of claim 3 , wherein stream S4 comprises more than 90% by weight propane.
7. The process of claim 1 , wherein a part of the non-reacted propene separated in step d) is combined with stream S3 to provide a propene feed to step c), said propene feed comprising from 2 to 20% by weight propane, and the remainder of the non-reacted propene separated in step d) is recycled as stream S5 to step b).
8. The process of claim 3 , wherein a part of the non-reacted propene separated in step d) is combined with stream S3 to provide a propene feed to step c), said propene feed comprising from 2 to 20% by weight propane, and the remainder of the non-reacted propene separated in step d) is recycled as stream S5 to step b).
9. The process of claim 5 , wherein a part of the non-reacted propene separated in step d) is combined with stream S3 to provide a propene feed to step c), said propene feed comprising from 2 to 20% by weight propane, and the remainder of the non-reacted propene separated in step d) is recycled as stream S5 to step b).
10. The process of claim 6 , wherein a part of the non-reacted propene separated in step d) is combined with stream S3 to provide a propene feed to step c), said propene feed comprising from 2 to 20% by weight propane, and the remainder of the non-reacted propene separated in step d) is recycled as stream S5 to step b).
11. The process of claim 1 , wherein, in step c), the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
12. The process of claim 3 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
13. The process of claim 5 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
14. The process of claim 7 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
15. The process of claim 8 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
16. The process of claim 9 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.
17. The process of claim 10 , wherein in step c) the initial molar ratio of propene to hydrogen peroxide is from 3:1 to 5:1.