Hydrogen-selective membrane

• US 5,451,386 A
• Filed: 05/19/1993
• Issued: 09/19/1995
• Est. Priority Date: 05/19/1993
• Status: Expired due to Fees

• Current Assignee: Oregon State University (Oregon University System)
• Original Assignee: Oregon State University (Oregon University System)
• Inventors: Way, J. Douglas, Collins, John P.
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US08/064,513
• Time in Patent Office: 853 Days
• Field of Search: 95/96, 96/8, 96/10, 423/351, 423/658.2, 423/237
• US Class Current: 423/237
• CPC Class Codes: B01D 2325/04 Characteristic thickness
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 53/229 Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• CPC Class Codes: B01D 53/8634 Ammonia
• CPC Class Codes: B01D 67/0069 by deposition from the liquid phase, e.g. electrochemical deposition B01D67/0046 takes precedence
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 69/1411 containing dispersed material in a continuous matrix
• CPC Class Codes: B01D 71/022 Metals
• CPC Class Codes: B01D 71/02231 Palladium
• CPC Class Codes: C01B 2203/041 In-situ membrane purification during hydrogen production
• CPC Class Codes: C01B 2203/0465 Composition of the impurity
• CPC Class Codes: C01B 2203/047 the impurity being carbon monoxide
• CPC Class Codes: C01B 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 2203/0495 the impurity being water
• CPC Class Codes: C01B 3/047 Decomposition of ammonia
• CPC Class Codes: C01B 3/505 Membranes containing palladium
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 μm but typically less than about 20 μm. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m².s at a temperature of greater than about 500° C. and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500° C. and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400° C. and less than about 1000° C. before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process.

Claims

1. A method for removing ammonia from a reaction mixture, comprising the steps of:

providing a mixture of gases that includes ammonia;

providing a composite ceramic-metal membrane that is impermeable to ammonia and which has a hydrogen-to nitrogen selectivity greater than achieved by Knudsen diffusion, the membrane comprising (a) a porous tubular ceramic support having a pore size of greater than about 10 nm, the ceramic support having an inside surface and an outside surface, and (b) a palladium metal layer deposited directly on the inside surface of the ceramic support, the metal layer being uniform and having a thickness of from about 10 μ

m to about 20 μ

m;

placing a catalyst inside the tubular ceramic support and adjacent the inside surface, the catalyst catalyzing the decomposition of ammonia to hydrogen and nitrogen;

flowing the mixture of gases through the tubular ceramic support so that the mixture contacts the catalyst, thereby decomposing ammonia to hydrogen gas and nitrogen gas; and

separating substantially pure hydrogen gas from the nitrogen gas using the ceramic-metal membrane.

2. The method according to claim 1 wherein the membrane has a hydrogen permeability of greater than about 1.0 moles/m².s at a temperature of greater than about 500°

C. and a transmembrane pressure difference of about 1,500 kPa.

3. The method according to claim 1 wherein the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500°

C. and a transmembrane pressure of about 700 kPa.

4. The method according to claim 1 wherein the mixture of gases is a mixture of exhaust gases from the IGCC process.