Gas distribution in oxidation reactions

Patent metadata

Field	Value
Publication number	US-10105668-B2
Application number	US-201615577030-A
Country	US
Kind code	B2
Filing date	Jun 3, 2016
Priority date	Jun 30, 2015
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

Systems, methods, and apparatus for distribution of oxygen-containing gas within a gas-liquid oxidation reaction are provided herein. The invention is particularly suited for oxidation of liquid-phase organic reactants with oxidizing gas, such as the oxidation of cyclohexylbenzene to cyclohexylbenzene hydroperoxide using an oxygen-containing gas. The oxygen-containing gas is distributed through a gas distributor and into a liquid-phase reaction medium within an oxidation reactor. In some aspects, this achieves a high degree of uniformity of oxygen concentration within the liquid-phase reaction medium. The gas distributor is disposed within a lower portion of the reactor, and may comprise a network of conduits in fluid communication with each other, which are arranged within a plane that is substantially parallel to a bottom surface of the reactor. A plurality of orifices are disposed on the conduits, such that oxygen-containing gas flows through the conduits and into the liquid-phase reaction medium via the orifices.

First claim

We claim:

1. A process comprising:
(a) providing a liquid feed comprising cyclohexylbenzene to an oxidation reactor, thereby forming a liquid-phase reaction medium in the oxidation reactor;
(b) providing an oxidation catalyst to the liquid-phase reaction medium, either together with or separately from the liquid feed;
(c) distributing an oxygen-containing gas into the liquid-phase reaction medium through a gas distributor, wherein the gas distributor (i) is disposed in a lower portion of the oxidation reactor, (ii) is submerged in the liquid-phase reaction medium, and (iii) comprises a network of conduits through which the oxygen-containing gas flows, said conduits being in direct or indirect fluid communication with one another and having disposed thereon a plurality of orifices through which the oxygen-containing gas passes from the conduits into the liquid-phase reaction medium; and
(d) forming cyclohexylbenzene hydroperoxide in the liquid-phase reaction medium;
wherein the conduits are disposed within a gas distributor horizontal cross-sectional area that is substantially parallel to a bottom surface of the oxidation reactor, and which occupies from 70 to 95% of the cross sectional area of the lower portion of the oxidation reactor in which the gas distributor is disposed; and
wherein there are on average 0.5-5 of the orifices per square foot within the gas distributor horizontal cross-sectional area.

2. The process of claim 1 , wherein the orifices are nozzles.

3. The process of claim 2 , wherein each nozzle is oriented such that the oxygen-containing gas exits the nozzle in (i) a direction within the plane of the distributor horizontal cross sectional area, (ii) a direction perpendicular to the distributor horizontal cross sectional area and toward a bottom of the oxidation reactor, or (iii) a direction at any angle therebetween.

4. The process of claim 1 , wherein the oxygen-containing gas, after being passed through the orifices, contacts the bottom of the oxidation reactor at least in part, and thereafter rises upward through the liquid phase reaction medium as a plurality of bubbles.

5. The process of claim 1 , wherein there are on average 1 to 2 of the orifices per square foot within the distributor horizontal cross sectional area.

6. The process of claim 1 , wherein each orifice through which the oxygen-containing gas flows is 3 to 6 mm in diameter.

7. The process of claim 1 , wherein the network of conduits is an arm distributor network comprising (i) 1 to 5 header conduits running parallel to each other through the distributor cross sectional area and (ii) 10 to 50 arm conduits each in fluid communication with at least one of the header conduits, and running through the distributor horizontal cross sectional area in a direction transverse to the header conduits.

8. The process of claim 7 , wherein the arm conduits each run substantially perpendicular to the header conduit(s).

9. The process of claim 7 , wherein the arm distributor network comprises (i) 2 header conduits running substantially parallel to each other and (ii) 23 arm conduits, each arm conduit being in fluid communication with both header conduits, and each arm conduit running substantially perpendicular to the header conduits.

10. The process of claim 1 , wherein the oxygen-containing gas is delivered to the liquid-phase reaction medium such that in any given continuous area of 10.0 centimeters by 10.0 centimeters inside (i) a first horizontal cross-section of the liquid-phase reaction medium 100 centimeters above the gas distributor, and/or (ii) a second horizontal cross-section of the liquid-phase reaction medium 500 centimeters above the gas distributor, the average quantity of oxygen passing through the given continuous area per second QO1 is in a range from 60% to 140% of QO2, where QO2 is the average quantity of oxygen passing through the whole given horizontal cross-section, expressed in terms of quantity of oxygen per 100 square centimeters per second.

11. The process of claim 10 , wherein the time-averaged gas volume fraction through the entirety of each of the first and second horizontal cross-sections of the liquid-phase reaction medium is less than 0.130 during the distributing (c); and further wherein the oxygen concentration in a vapor-phase headspace in the reactor above the liquid-phase reaction medium remains at or below 8 vol % during the distributing (c).

12. The process of claim 1 , wherein the oxidation reactor is a cylinder of average diameter D centered upon a reactor vertical axis, and further wherein the distributor horizontal cross-sectional area is centered upon the reactor vertical axis.

13. The process of claim 12 , wherein the average diameter D is from 35 ft (10.668 m) to 100 ft (30.480 m).

14. The process of claim 13 , wherein the average diameter D is from 35 ft (10.668 m) to 50 ft (15.240 m); and wherein the process further comprises:
(e) obtaining a first oxidation effluent comprising the cyclohexylbenzene hydroperoxide and unreacted cyclohexylbenzene from the liquid-phase reaction medium;
(f) providing the first oxidation effluent and additional oxidation catalyst to a second oxidation reactor having diameter D2 from 50 ft (15.240 m) to 70 ft (21.336 m), forming therein a second liquid-phase reaction medium;
(g) distributing additional oxygen-containing gas into the second liquid-phase reaction medium through a second gas distributor, wherein the second gas distributor (i) is disposed in a lower portion of the second oxidation reactor, (ii) is submerged in the second liquid-phase reaction medium, and (iii) comprises a network of additional conduits through which the additional oxygen-containing gas flows, said additional conduits being in direct or indirect fluid communication with one another and having disposed thereon a plurality of additional orifices through which the additional oxygen-containing gas passes from the additional conduits into the second liquid-phase reaction medium; and
(h) forming additional cyclohexylbenzene hydroperoxide in the second liquid-phase reaction medium;
wherein the additional conduits run substantially parallel to, and are disposed within, a second distributor horizontal cross-sectional area that is from 70 to 95% of the cross sectional area of the lower portion of the second oxidation reactor in which the second gas distributor is disposed; and
wherein there are on average 0.5-5 of the additional orifices per square foot within the second distributor horizontal cross sectional area.

15. The process of claim 14 , and further comprising:
(i) obtaining a second oxidation effluent comprising the cyclohexylbenzene hydroperoxide, the additional cyclohexylbenzene hydroperoxide, and a portion of the unreacted cyclohexylbenzene from the second liquid-phase reaction medium;
(j) providing the second oxidation effluent and further oxidation catalyst to a third oxidation reactor having diameter D3 from 85 ft (25.908 m) to 100 ft (30.480 m), forming therein a third liquid-phase reaction medium;
(k) distributing further oxygen-containing gas into the third liquid-phase reaction medium through a third gas distributor, wherein the third gas distributor (i) is disposed in a lower portion of the third oxidation reactor, (ii) is submerged in the third liquid-phase reaction medium, and (iii) comprises a network of further conduits through which the further oxygen-containing gas flows, said further conduits being in direct or indirect fluid communication with one another and having disposed thereon a plurality of further orifices through which the further oxygen-containing gas passes from

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Igci Yesim
• Patel Bryan A
• Chang Min

Classifications

• C07C409/14

  the carbon atom belonging to a ring other than a six-membered aromatic ring · CPC title

• C07C407/00

  Preparation of peroxy compounds · CPC title

• C07C2601/14

  The ring being saturated · CPC title

• B01J8/22 Primary

  gas being introduced into the liquid · CPC title

• B01J4/004

  Sparger-type elements · CPC title