Separation device

• US 4,685,940 A
• Filed: 07/30/1985
• Issued: 08/11/1987
• Est. Priority Date: 03/12/1984
• Status: Expired due to Term

• Current Assignee: Abraham Soffer, Jacob E. Koresh, Shlomo Saggy
• Original Assignee: Abraham Soffer, Jacob E. Koresh, Shlomo Saggy
• Inventors: Koresh, Jacob E., Saggy, Shlomo, Soffer, Abraham
• Primary Examiner(s): Spitzer, Robert
• Application Number:
  US06/760,529
• Time in Patent Office: 742 Days
• Field of Search: 55/16, 55/158, 210/500.2, 423/447.1, 423/447.2, 423/447.7, 423/447.9, 423/449
• US Class Current: 96/8
• CPC Class Codes: B01D 2325/0283 Pore size
• CPC Class Codes: B01D 2325/20 Specific permeability or cut-off range
• CPC Class Codes: B01D 67/0067 by carbonisation or pyrolysis
• CPC Class Codes: B01D 67/0083 Thermal after-treatment
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/021 Carbon
• CPC Class Codes: C04B 2111/00801 Membranes; Diaphragms
• CPC Class Codes: C04B 35/52 based on carbon, e.g. graphite
• CPC Class Codes: C04B 38/0022 obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors
• CPC Class Codes: C04B 41/00 After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone conditioning of the materials prior to shaping C04B40/00; applying liquids or other fluent materials to surfaces, in general B05; grinding or polishing B24; apparatus or processes for treating or working shaped articles of clay or other ceramic compositions, slag or mixtures containing cementitious material B28B11/00; working stone or stone-like materials B28D; glazes, other than cold glazes, C03C8/00; etching, surface-brightening or pickling compositions C09K13/00

Abstract

There are provided carbon membranes for use in separation processes. These have a very narrow range of pore sizes, with a very sharp cutoff at the upper pore size, and thus they are suited for the separation of various constituents which differ but little in their size. The membranes can be of a varied configuration: sheet form, tubular form, assymetrical membranes and the like. There is provided a process for the production of such membranes by controlled pyrolysis of a carbon containing percursor material.

Claims

1. A carbon membrane for separating two gases having different size molecules in a range of 2.5 Å

to 5.0 Å

, wherein the molecules of each gas differ from one another in size by an amount not greater than 10%, said membrane having pores of a preselected size which also is in the range of 2.5 Å

to 5.0 Å and

which is intermediate the molecule sizes of the two gases to be separated, and said membrane having a pore size distribution which is such that the membrane has no significant number of pores which are 10% or greater in size than the smaller of the molecule sizes of the two gases.

2. A carbon membrane according to claim 1, wherein the membrane is in sheet form and of from 1μ

to 300μ

thickness.

3. Carbon membranes according to claim 1, in the form of tubular fibers, of from 5μ

to 1 mm diameter and with a wall thickness of 1μ

to 300μ

, depending on the diameter, of desired length.

4. A separation module of the shell and tube type comprising a plurality of hollow carbon fibers as claimed in claim 3.

5. A carbon membrane according to claim 1, wherein the carbon membrane is of assymetrical construction, and the active carbon membrane is 50μ

to 300μ

in thickness and supported by a porous support of adequate mechanical strength.

6. A separation module for the separation of gaseous mixtures comprising a plurallity of assymmetrical carbon membranes according to claim 5, in a membrane stack configuration.

7. A carbon membrane according to claim 1, wherein the carbon membrane is the product of pyrolysis of a carbon containing precursor at a temperature of from 250°

C. to 2500°

C.

8. A carbon membrane according to claim 1, wherein the carbon membrane is the product of pyrolysis of a suitable precursor and subsequent pore size manipulation by heat treatment or by controlled oxidation.

9. A process for the production of a carbon membrane for a separation process as claimed in claim 1, which comprises pyrolyzing under an inert atmosphere a mechanically heat stable carbon containing precursor material having the configuration of the final product.

10. A process according to claim 9 wherein the pyrolysis is effected at a temperature between 250°

C. and 2500°

C.

11. A process according to claim 9, wherein the precursor is cellulose, a cellulose derivative, a thermosetting polymer or peach tar mesophase having the configuration of the desired product, with the pore size range of the precursor being determined by the temperature of pyrolysis and being in the range of 2.5 Å

to 5.0 Å

.