Microwave transparent vessel for microwave assisted chemical processes

• US 6,258,329 B1
• Filed: 04/20/1998
• Issued: 07/10/2001
• Est. Priority Date: 04/20/1998
• Status: Expired due to Term

• Current Assignee: CEM Global LLC
• Original Assignee: CEM Global LLC
• Inventors: Mutterer, James Nelson Jr., Hargett, Wyatt Price Jr.
• Primary Examiner(s): TRAN, HIEN THI
• Application Number:
  US09/062,979
• Time in Patent Office: 1,177 Days
• Field of Search: 422/21, 422/101, 422/186, 422/186.04, 422/186.29, 422/906, 422/102, 422/99, 219/686, 219/687, 219/756, 204/157.15, 204/157.43
• US Class Current: 422/186.29
• CPC Class Codes: B01J 19/126 Microwaves
• CPC Class Codes: B01J 2219/00056 involving measured parameters
• CPC Class Codes: B01J 2219/00058 Temperature measurement
• CPC Class Codes: B01J 2219/00065 Pressure measurement
• CPC Class Codes: B01J 2219/1218 Multiple reactors

Abstract

A system for carrying out microwave assisted chemical reactions is disclosed. The system includes a source of microwave radiation; a cavity in communication with the source, an attenuator in communication with the cavity for providing access to the cavity while preventing microwaves from escaping through the attenuator, and a vessel positioned in the cavity and the attenuator and extending externally of the attenuator for holding materials in the cavity while microwaves from the source are applied thereto. The vessel includes a reaction chamber and a venting portion. The chamber portion is positioned entirely within the cavity, and the venting portion extends from the cavity and through the attenuator and externally of the attenuator and has a gas passage for permitting gases to flow to or from the reaction portion from gas sources external to the cavity, the attenuator, and the vessel.

Claims

1. A system for carrying out microwave assisted chemistry, comprising:

a source of microwave radiation;

a cavity in communication with said source;

an attenuator in communication with said cavity for providing access to said cavity while preventing microwaves from escaping through said attenuator; and

a microwave-transparent, substantially cylindrical vessel vertically and removably positioned in said cavity and said attenuator and extending externally of said attenuator, said vessel capable of holding materials in said cavity while microwaves from said source are applied thereto;

said vessel further comprising a reaction chamber and a venting portion;

said reaction chamber being positioned entirely within said cavity;

said venting portion being positioned adjacent to said reaction chamber, and extending from said cavity, and extending through said attenuator, and extending externally of said attenuator; and

said venting portion further comprising a plurality of passageways extending longitudinally from said reaction chamber entirely through said venting portion, said passageways comprising an axial passageway for exhausting vapors and gases from said vessel and a parallel passageway for allowing ambient gases from sources external to said vessel to enter said reaction chamber below said axial passageway to thereby lift the vapors and gases and promote efficient evaporation of liquids.

2. A microwave system according to claim 1 comprising a plurality of said cavities, with each said cavity having an associated attenuator and an associated microwave-transparent vessel.

3. A microwave system according to claim 2 wherein the source of microwave radiation is a single microwave source, and all of said cavities are in communication with said single microwave source.

4. A microwave system according to claim 2 wherein said microwave source comprises a magnetron.

5. A microwave system according to claim 3 and further comprising individually adjustable microwave moderating means between each said cavity and said single microwave source for adjusting the microwave radiation that reaches each said cavity from said single microwave source.

6. A microwave system according to claim 5 and further comprising a sensor associated with each said vessel for monitoring the conditions of said vessel and the reaction therein.

7. A microwave system according to claim 6 wherein said sensors are selected from the group consisting of temperature sensors, pressure sensors, photodetectors and electrochemical detectors.

8. A microwave system according to claim 6 and further comprising a control system operatively associated with said moderating means and said sensors for adjusting said moderating means in response to said sensors.

9. A microwave system according to claim 1 wherein said attenuator extends vertically upwardly from said cavity and said vessel is vertically oriented in said attenuator and said cavity.

10. A microwave system according to claim 1 wherein said vessel comprises:

a cylinder formed of a microwave-transparent material that is resistant to chemical attack;

said reaction chamber formed adjacent one end of said cylinder, said chamber forming less than the total solid volume of said cylinder; and

means for drawing fluids through at least one passageway quickly enough to avoid condensation of hot vapors in the cylinder.

11. A system for carrying out microwave assisted chemistry, comprising:

a source of microwave radiation;

a cavity in communication with said source;

an attenuator in communication with said cavity, said attenuator providing access to said cavity while preventing microwaves from escaping from said attenuator;

a cylindrical vessel or cylinder formed of a microwave-transparent material that is resistant to chemical attack, said cylinder vertically and removably positioned in said cavity and said attenuator, and extending externally of said attenuator;

a reaction chamber formed adjacent one end of said cylinder and being positioned within said cavity, said chamber forming less than the total solid volume of said cylinder;

a plurality of fluid passageways positioned longitudinally in said cylinder and extending from said chamber to the opposite end of said cylinder from said chamber, said passageways comprising an axial passageway for exhausting vapors and gases from said cylinder and a parallel passageway for allowing ambient gases from sources external to said cylinder to enter said reaction chamber below said axial passageway to thereby lift the vapors and gases and promote efficient evaporation of liquids during microwave assisted chemical processes; and

means for drawing vapors and gases through said axial passageway quickly enough to avoid condensation of hot vapors and gases in the cylinder.

12. A microwave system according to claim 11 wherein said cylinder comprises two pieces that are separable at a position that permits chemical compositions to be added to said reaction chamber.

13. A microwave system according to claim 11 wherein said cylinder is formed of a tetrafluoroethylene (PTFE) polymer.

14. A microwave system according to claim 11 wherein said cylinder is formed of glass.

15. A microwave system according to claim 11, wherein the plurality of fluid passageways further comprises an additional passageway parallel to said axial passageway.

16. A microwave system according to claim 15 wherein said fluid drawing means comprise threaded tubing adapters at the end of each said passageway at the opposite end of said cylinder.

17. A microwave system according to claim 11 wherein the portion of said cylinder other than said reaction chamber comprises a cylindrical frame and said fluid passageways comprise a plurality of tubes supported on said frame.

18. A system for carrying out microwave assisted chemistry, comprising:

a source of microwave radiation;

a cavity in communication with said source;

a reaction chamber cylinder formed of a material that is microwave transparent and resistant to chemical attack, said reaction chamber vertically and removably positioned within said cavity and having a closed end and a mouth, and including a male sleeve extending from said mouth of said reaction chamber cylinder;

a venting cylinder formed of the same material as said reaction chamber cylinder and including a female sleeve that fits over said male sleeve of said reaction chamber cylinder for engaging said reaction chamber cylinder to said venting cylinder; and

a plurality of passageways extending longitudinally entirely through said venting cylinder, said passageways comprising an axial passageway for exhausting vapors and gases from said reaction chamber cylinder and a parallel passageway for allowing ambient gases from sources external to said reaction chamber cylinder and said venting cylinder to enter said reaction chamber cylinder below said axial passageway to thereby lift the vapors and gases and promote efficient evaporation of liquids when said reaction chamber cylinder and said venting cylinder are engaged.

19. A microwave system according to claim 18, wherein said plurality of passageways further comprises an additional passageway parallel to said axial passageway.

20. A microwave system according to claim 18 further comprising hose fittings at the terminal ends of said passageways.

21. A microwave system according to claim 18, wherein said cylinders are formed of a tetrafluoroethylene polymer.