Propylene oxide process
View Patent ↗A process for making propylene oxide from propylene is disclosed. Propylene, hydrogen, and oxygen are reacted in a slurry comprising a catalyst and a solvent to produce a gaseous product stream and a liquid product stream. The gaseous product stream is contacted with an absorbent to produce a gas effluent and a liquid effluent. The gas effluent is recycled to the reaction step.
1. A process for producing propylene oxide comprising
(a) reacting propylene, oxygen, and hydrogen in a slurry comprising a catalyst and a solvent to produce propylene oxide, wherein the propylene oxide is present in a gaseous product stream and a liquid product stream;
(b) contacting the gaseous product stream with an absorbent to produce a gas effluent and a liquid effluent; and
(c) recycling the gas effluent to the step (a).
2. The process of claim 1 wherein the gaseous product stream comprises at least 10 percent of the propylene oxide produced in the step (a).
3. The process of claim 2 wherein the gaseous product stream comprises at least 20 percent of the propylene oxide produced in the step (a).
4. The process of claim 1 wherein the gas effluent comprises less than 0.1 mole percent propylene oxide.
5. The process of claim 1 wherein the gas effluent comprises less than 0.01 mole percent propylene oxide.
6. The process of claim 1 wherein the solvent is selected from the group consisting of water, methanol, and mixtures thereof.
7. The process of claim 1 wherein the absorbent is a recycled solvent from the process.
8. The process of claim 1 wherein the catalyst comprises a transition metal zeolite and a noble metal.
9. The process of claim 1 wherein the catalyst has a concentration in the range of from 5 to 30 wt % relative to the slurry.
10. The process of claim 1 wherein the step (a) is performed in a slurry bubble-column reactor.
11. The process of claim 10 wherein the reactor content is mixed by gas bubbles in a churn-turbulent flow regime.
12. The process of claim 10 wherein the reactor is cylindrical and has a diameter of greater than 0.2 meter and a height-to-diameter ratio of greater than 3:1.
13. The process of claim 10 wherein the propylene, oxygen, and hydrogen are fed at or near the bottom of the reactor.
14. The process of claim 1 wherein the step (a) is performed at a temperature in the range of from 30 to 100° C.
15. The process of claim 1 wherein the step (a) is performed at a pressure in the range of from 150 to 400 psig.