Graphite composite chips

• US 4,631,200 A
• Filed: 05/17/1985
• Issued: 12/23/1986
• Est. Priority Date: 05/17/1985
• Status: Expired due to Term

• Current Assignee: H-D Tech Incorporated
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Bierschenk, Thomas R.
• Primary Examiner(s): Lusignan, Michael R.
• Application Number:
  US06/734,996
• Time in Patent Office: 585 Days
• Field of Search: 427/113, 427/115, 427/122, 427/385.5, 427/221, 204/294, 204/290 R
• US Class Current: 427/113
• CPC Class Codes: C25B 11/043 Carbon, e.g. diamond or graphene
• CPC Class Codes: C25B 9/40 Cells or assemblies of cells comprising electrodes made of particles; Assemblies of constructional parts thereof
• CPC Class Codes: C25B 9/70 Assemblies comprising two or more cells
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

For use in trickle bed electrolytic cells, the preferred and illustrated embodiment sets forth an improved graphite composite chip. It is a chip characterized by having a much higher percentage with a more uniform coating thereon. The coating has the form of a mix of carbon and Teflon on graphite chips. It is more uniform and applied to both sides of the chips. This improves current flow and distribution in an electrolytic cell such as a hydrogen peroxide cell. One procedure taught herein is a method of making such composite chips on graphite wherein carbon in particulate form is mixed with water and particulate Teflon dispersion and is added to graphite chips of a selected mesh size; after mixing, the water is drained and all water is removed by a vacuum in a rotary evaporator whereupon the dried material is then sintered for a specified time and temperature.

Claims

1. A method for making composite chips for use in packed bed electrolytic cells featuring a uniform coating of carbon and Teflon on graphite chips wherein the method comprises:

(a) preliminarily washing particulate carbon with a metal removing wash;

(b) mixing the washed particulate carbon with a fluorocarbon dispersion in water and adding thereto graphite chips having a specified mesh;

(c) removing the water until dry; and

(d) sintering the dried material at an elevated temperature for a specified interval wherein the coating material is applied to an average thickness of about 90 microns on about 95% or more of the graphite chips so treated.

2. The method of claim 1 including applying a second application of carbon and fluorocarbon dispersed in water on graphite chips after a first application.

3. The method of claim 2 including the step of adding a small quantity of surfactant to the water for the second application.

4. The method of claim 1 wherein the preliminary step of washing the carbon uses 30% hydrochloric acid for about one hour, thereafter filtering, rinsing and drying the carbon to remove metal therefrom.

5. The method of claim 1 wherein the carbon is approximately 2.75 grams of carbon, and the fluorocarbon dispersion is about 4 cc of 70% Teflon, and both are mixed in a suitable quantity of water.

6. The method of claim 5 wherein about 75 grams of graphite are mixed in the water, the graphite having a mesh between about -10 and about +20.

7. The method of claim 1 wherein the step of removing water under vacuum involves rotary spinning in vacuum at an elevated temperature reaching about 100°

C.

8. The method of claim 1 including the step of sintering to about 350°

for about one hour.