Production of highly microporous activated carbon products

• US 5,416,056 A
• Filed: 10/25/1993
• Issued: 05/16/1995
• Est. Priority Date: 10/25/1993
• Status: Expired due to Term

• Current Assignee: Meadwestvaco (WestRock Company)
• Original Assignee: Westvaco Corporation (Meadwestvaco Corporation)
• Inventors: Baker, Frederick S.
• Primary Examiner(s): MCFARLANE, ANTHONY R
• Application Number:
  US08/143,551
• Time in Patent Office: 568 Days
• Field of Search: 502/425, 502/426, 502/427, 502/416, 502/417, 502/437, 502/526
• US Class Current: 502/425
• CPC Class Codes: C01B 32/30 Active carbon
• CPC Class Codes: C01B 32/318 characterised by the starting materials
• CPC Class Codes: C01B 32/342 characterised by non-gaseous activating agents
• CPC Class Codes: C01B 32/348 Metallic compounds
• CPC Class Codes: F02B 43/00 Engines characterised by operating on gaseous fuels; Plants including such engines engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel F02B7/06; engines convertible from gas to other fuel consumption F02B69/04
• CPC Class Codes: F02F 7/0085 Materials for constructing engines or their parts
• CPC Class Codes: F17C 11/007 for hydrocarbon gases, such as methane or natural gas, propane, butane or mixtures thereof [LPG]
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A two-stage process for chemical activation of lignocellulose-derived carbon is disclosed comprising a first activation stage of blending a lignocellulose material with phosphoric acid, carbonizing the blend at from about 300° F. to about 1,100° F. (about 150°-590° C.), and water washing the carbonized material and a second activation stage of blending the carbonized material with a potassium hydroxide solution, activating this blend at from about 1,200° to about 1,800° F. (about 650°-980° C.), and water washing and drying the microporous activated carbon product, which is characterized by greater than 50% of its total pore volume comprising pores of less than 16 Å in width and greater than 80% of its total pore volume comprising pores of less than 20 Å in width and greater than 95% of its total pore volume comprising pores of less than 50 Å in width.

Claims

1. A process for the manufacture of microporous activated carbon comprising sequential chemical activation stages including:

a first activation stage comprising the steps of forming a first blend of a lignocellulose material with phosphoric acid, carbonizing the first blend at from about 300°

to about 1,100°

F. (about 150°

-590°

C.), and water washing the carbonized material; and

a second activation stage comprising the steps of forming a second blend of the carbonized material and a potassium hydroxide solution, activating the second blend at from about 1,200°

to about 1,800°

F. (about 650°

-980°

C.), and water washing and drying the microporous activated carbon product which is characterized by greater than 80% of total pore volume comprising pores of less than 20 Å

in width and greater than 95% of total pore volume comprising pores of less than 50 Å

in width.

2. The process of claim 1 wherein the microporous activated carbon is characterized by greater than 50% of total pore volume comprising pores of less than 16 Å

in width and greater than 95% of total pore volume comprising pores of less than 50 Å

in width.

3. The process of claim 1 wherein the lignocellulose material is selected from the group consisting of wood chips, sawdust, wood flour, and coconut shell.

4. The process of claim 1 wherein the first blend comprises a ratio of phosphoric acid to lignocellulose material of from 1:

1 to 3;

1 and the second blend comprises a ratio of potassium hydroxide to carbonized material of from 0.5;

1 to 4;

1.

5. The process of claim 1 wherein the phosphoric acid is recovered in the washing step of the first activation stage and recycled for use in the first blend, and the potassium hydroxide is recovered as alkali in the washing step of the second activation stage and, following regeneration of the alkali, recycled for use in the second blend.