US PATENT SUBCLASS 95 / 45
.~ Selective diffusion of gases through substantially solid barrier (e.g., semipermeable membrane, etc.)

Current as of: June, 1999
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95 /   HD   GAS SEPARATION: PROCESSES

43  DF  SELECTIVE DIFFUSION OF GASES {2}
45.~ Selective diffusion of gases through substantially solid barrier (e.g., semipermeable membrane, etc.) {10}
46  DF  .~.~> Degasification of liquid
47  DF  .~.~> Nitrogen or nitrogen containing compound permeates barrier
48  DF  .~.~> Halogen containing compound permeates barrier
49  DF  .~.~> Sulfur containing compound permeates barrier
50  DF  .~.~> Organic compound permeates barrier
51  DF  .~.~> Carbon dioxide or carbon monoxide permeates barrier
52  DF  .~.~> Water vapor permeates barrier
53  DF  .~.~> Helium permeates barrier
54  DF  .~.~> Oxygen permeates barrier
55  DF  .~.~> Hydrogen permeates barrier {1}

DEFINITION

Classification: 95/45

Selective diffusion of gases through substantially solid barrier (e.g., semipermeable membrane, etc.):

(under subclass 43) Process in which a plurality of gases or a mixture of gas entrained in a liquid contacts a substantially solid surface (e.g., semipermeable membrane, etc.) and a gas is separated from another gas or a gas is separated from the liquid because of the differential permeability of the surface of the solid with respect to the gases.

(1) Note. Class 95 will take dissociation of a gas molecule at the barrier boundary when such dissociation facilitates passage of the gas through the barrier; the atoms reconvert to the gas molecule on the downstream side of the barrier. If the dissociation of the gas occurs away from the barrier and a resulting product diffuses through the barrier, then the patent will be in Class 423 for an inorganic gas and in the appropriate organic class for an organic gas.

SEE OR SEARCH CLASS

205, Electrolysis: Processes, Compositions Used Therein, and Methods of Preparing the Compositions,

334+, for processes using a solid electrolyte membrane (SEM) situated between two electrodes positioned to apply external voltage across the membrane. These membranes are used where the partial pressure of the gas to be diffused through the membrane on the feed side of the membrane is lower than that on the permeate side. Molecules on the feed side of a cell containing a solid electrolyte membrane are electrochemically dissociated into ions on the cathode. The ions are then transported across the matrix of the membrane by the applied

voltage and recombined to form molecules on the anode. Class 95 takes the use of a solid electrolyte membrane which functions without electrodes and without externally applied voltage. These membranes are used where the partial pressure of the gas to be diffused through the membrane on the permeate side is lower than that on the feed side. Electrodeless solid electrolyte membrane cells are operated by maintaining a pressure on the feed side such that a positive driving force for ion transport can be achieved in the absence of an externally applied voltage and power source.

210, Liquid Purification or Separation,

96.2, 257.2, and 321.6+ for apparatus having membranes or dialyzers for separating liquids, subclasses 500.21+ for semipermeable membranes used in the separation of liquids, and subclasses 634+ for processes of separating a liquid by selective diffusion of a component of a liquid through a membrane or septum. 427, Coating Processes,

245+, for methods of coating a base so that the resulting product is foraminous or porous, wherein the coating includes openings or holes which are very small, generally microscopic in size.

520, Synthetic Resins or Natural Rubbers, for synthetic resins or natural rubbers that may be used for selective diffusion of gases.

585, Chemistry of Hydrocarbon Compounds,

818+, for processes in which a liquid hydrocarbon is recovered from a liquid mixture containing the hydrocarbon by the use of selective diffusion through a semipermeable membrane.