Aerogel and metallic compositions

• US 20070142222A1
• Filed: 10/24/2006
• Published: 06/21/2007
• Est. Priority Date: 12/27/2001
• Status: Abandoned Application

• Current Assignee: Aerogel Composite LLC, University of Connecticut (State of Connecticut)
• Original Assignee: Aerogel Composite LLC, University of Connecticut (State of Connecticut)
• Inventors: Hara, Hiroaki, Erkey, Can
• Application Number:
  US11/585,578
• Publication Number:
  US 20070142222A1
• Time in Patent Office: Days
• US Class Current: 502/237
• CPC Class Codes: B01J 21/18 Carbon
• CPC Class Codes: B01J 23/40 of the platinum group metals
• CPC Class Codes: B01J 35/10 characterised by their surface properties or porosity
• CPC Class Codes: B01J 35/1023 500-1000 m2/g
• CPC Class Codes: B01J 35/1042 0.5-1.0 ml/g
• CPC Class Codes: B01J 35/1047 more than 1.0 ml/g
• CPC Class Codes: B01J 35/1061 2-50 nm
• CPC Class Codes: B01J 35/60 characterised by their surface properties or porosity
• CPC Class Codes: B01J 35/617 500-1000 m2/g
• CPC Class Codes: B01J 35/635 0.5-1.0 ml/g
• CPC Class Codes: B01J 35/638 more than 1.0 ml/g
• CPC Class Codes: B01J 35/647 2-50 nm
• CPC Class Codes: B01J 37/0203 the impregnation liquid containing organic compounds
• CPC Class Codes: B01J 37/03 Precipitation; Co-precipitation
• CPC Class Codes: B01J 37/084 Decomposition of carbon-containing compounds into carbon
• CPC Class Codes: C04B 14/028 Carbon aerogels
• CPC Class Codes: C04B 14/064 Silica aerogel
• CPC Class Codes: C04B 14/302 Aerogels
• CPC Class Codes: C04B 14/34 Metals , e.g. ferro-silicon
• CPC Class Codes: C04B 14/386 Carbon carbon nanotubes C04B14/026
• CPC Class Codes: C04B 20/0056 : Hollow or porous fibres
• CPC Class Codes: C04B 20/008 : Micro- or nanosized fillers, e.g. micronised fillers with particle size smaller than that of the hydraulic binder colloidal silica C04B14/062 ; silica fume C04B18/146
• CPC Class Codes: C04B 2103/007 : Supercritical fluids
• CPC Class Codes: C04B 2111/00413 : Materials having an inhomogeneous concentration of ingredients or irregular properties in different layers
• CPC Class Codes: C04B 2111/00853 : in electrochemical cells or batteries, e.g. fuel cells
• CPC Class Codes: C04B 30/00 : Compositions for artificial stone, not containing binders
• 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 38/0045 : by a process involving the formation of a sol or a gel, e.g. sol-gel or precipitation processes
• CPC Class Codes: C04B 38/009 : Porous or hollow ceramic granular materials, e.g. microballoons C04B18/027, C04B20/002 take precedence
• CPC Class Codes: C04B 41/0072 : Heat treatment
• CPC Class Codes: C04B 41/009 : characterised by the material treated
• CPC Class Codes: C04B 41/4554 : the coating or impregnating material being an organic or organo-metallic precursor of an inorganic material
• CPC Class Codes: C04B 41/4582 : Porous coatings, e.g. coating containing porous fillers
• CPC Class Codes: C04B 41/5001 : with carbon or carbonisable materials
• CPC Class Codes: C04B 41/51 : Metallising , e.g. infiltration of sintered ceramic preforms with molten metal covering materials with metals in general C23C; ceramic compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides, other than as macroscopic reinforcing agents C22C; infiltration of preforms containing free metal, e.g. cermets C22C
• CPC Class Codes: H01M 4/9008 : Organic or organo-metallic compounds
• CPC Class Codes: H01M 4/9075 : Catalytic material supported on carriers, e.g. powder carriers H01M4/8807, H01M4/881, H01M4/8814, H01M4/925 take precedence
• CPC Class Codes: H01M 4/9083 : on carbon or graphite
• CPC Class Codes: H01M 4/923 : Compounds thereof with non-metallic elements
• CPC Class Codes: H01M 4/925 : supported on carriers, e.g. powder carriers
• CPC Class Codes: H01M 4/926 : on carbon or graphite
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

Metallic aerogel compositions comprising an aerogel, e.g., RF or carbon aerogel, having metallic particles dispersed on its surface are disclosed. The aerogel compositions can have a uniform distribution of small metallic particles, e.g., 1 nanometer average particle diameter. Also disclosed are processes for making the aerogel compositions comprising contacting an aerogel with a supercritical fluid containing a metallic compound. The aerogel compositions are useful, for example in the manufacture of fuel cell electrodes.

Claims

1-32. -32. (canceled)

33. A method for producing metal particles or mixed metal particles dispersed on a particulate substrate comprising:

a. exposing an organometallic and the particulate substrate to a supercritical or near supercritical fluid under conditions to form a mixture of the fluid and the organometallic;

b. allowing the mixture to remain in contact with the substrate for a time sufficient to deposit dispersed organometallic onto the substrate;

c. venting the mixture;

d. thereby adsorbing the organometallic onto the substrate; and

then

e. reducing the dispersed organometallic to dispersed metal particles with a reducing agent.

37. The method of claim 33, wherein the metal particles are nanoparticles.

38. The method of claim 37, whrein the nanoparticles are about 1 nm to about 4 nm in average diameter.

39. The method of claim 33, wherein the metal particles are noble metal particles.

40. The method of claim 33, wherein the metal particles comprise platinum, iridium, ruthenium, rhodium, palladium, chromium, gold, silver, nickel, cobalt, or a mixture thereof, or an alloy thereof.

41. The method of claim 33, wherein the metal particles comprise platinum.

42. The method of claim 33, wherein the metal particles comprise silver.

43. The method of claim 33, wherein the metal particles comprise ruthenium.

44. The method of claim 33, wherein the metal particles are mixed metal particles.

45. The method of claim 33, wherein the fluid comprises carbon dioxide, ethane, or propane.

46. The method of claim 33, wherein the reducing is by addition of a reducing agent.

47. The method of claim 46, wherein the reducing agent comprises hydrogen.

48. The method of claim 33, wherein the organometallic is adsorbed while in the mixture.

49. The method of claim 33, wherein the organometallic is adsorbed when the mixture is vented.

50. The method of claim 33, wherein in step (a), at least some of the organometallic dissolves in the fluid.

51. The method of claim 33, wherein in step (a), all or substantially all of the organometallic dissolves in the fluid.

52. The method of claim 33, wherein the method produces a supported particulate catalyst suitable for use in a fuel cell.

55. The method of claim 33, wherein the particulate substrate is a porous particulate substrate.

53. A method for producing particulate substrate-supported dispersed metallic particles comprising:

a. mixing an organometallic in a supercritical or near supercritical fluid to form a mixture;

b. exposing a particulate substrate to the mixture of a) under supercritical or near supercritical conditions for a period of time sufficient to deposit dispersed organometallic on the substrate;

c. venting the mixture;

d. thereby adsorbing the organometallic onto the substrate; and

then

e. reducing the organometallic to dispersed metal particles with a reducing agent.

54. A method for producing particulate substrate-supported dispersed metallic particles comprising;

a. adding a particulate substrate and an organometallic to a reactor;

b. adding a supercritical fluid to the reactor to form a mixture with the organometallic;

c. allowing the organometallic to remain in contact with the substrate for a time sufficient to deposit dispersed organometallic onto the substrate;

d. venting the reactor;

e. thereby adsorbing the organometallic onto the substrate; and

then

f. adding a gaseous reducing agent to the reactor; and

g. contacting the reducing agent and organometallic until the organometallic is reduced to dispersed metal particles.

56. A method for producing metal particles or mixed metal particles dispersed on a surface of a substrate comprising;

exposing an organometallic and the surface to a supercritical or near supercritical fluid in a reactor under conditions to form a mixture of the fluid and the organometallic;

allowing the mixture to remain in contact with the surface for a time sufficient to deposit dispersed organometallic onto the surface;

depressurizing the reactor; and

then

reducing the dispersed organometallic to dispersed metal or mixed metal particles.

57. The method of claim 57, wherein the substrate is a porous substrate.