Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Free carbon containing
Reexamination Certificate
1999-09-14
2001-05-01
Hendrickson, Stuart L. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Free carbon containing
C423S460000
Reexamination Certificate
active
06225257
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to the field of storage media for methane and natural gas. More particularly, the invention pertains to a method of enhancing a microporous carbon adsorbent to improve its natural gas storage capability.
BACKGROUND OF THE INVENTION
It is known that the density of gaseous methane can be enhanced in a storage vessel with the use of a carbonaceous adsorbent material having pores in a specified and limited range of diameters. In addition, activated carbons with a good microporous structure, but undesired microstructure, show lower working capacity. Therefore, there is always a compromise between the microporosity of the adsorbent where the enhancement effect takes place and the bulk density of the adsorbent, which determines the filling capacity of the storage system. Thus, the essential and principal feature of this invention is to provide post-carbonization treatment procedures which are applied to existing and preselected microporous carbons, which as a result of these treatments, then exhibit increased enhancement properties as storage media for methane and natural gas.
U.S. Pat. No. 5,071,820 (Quinn) entitled CARBONACEOUS MATERIAL WITH HIGH MICROPORE AND LOW MACROPORE VOLUME AND PROCESS FOR PRODUCING SAME discloses a two-step procedure for making activated carbon that involves heating the carbon to 150-200° C. in oxygen for 45-75 minutes, after which the oxygen is purged with nitrogen, and then the carbon is heated to 750-900° C. in nitrogen for 15-45minutes. The process can be repeated depending on the extent of microporosity desired.
U.S. Pat. No. 5,614,460 (Schwarz) entitled MICROPOROUS CARBONS FOR FUEL GAS STORAGE discloses a method for making activated carbon, known as CNDS synthetic activated carbon, by using crystalline salts of aromatic sulfonates as precursors.
U.S. Pat. No. 5,385,876 (Schwarz) entitled ACTIVATED CARBONS MOLECULARLY ENGINEERED discloses a method for making microporous carbon adsorbent material using an inorganic matrix and active carbon supported within the matrix.
U.S. Pat. No. 5,372,619 (Greinke) entitled METHOD FOR STORING METHANE USING A HALOGENATING AGENT TREATED ACTIVATED CARBON discloses a method for making a halogenated or sulfonated active carbon which has a high storage capacity for methane.
U.S. Pat. No. 4,499,208 (Fuderer) entitled ACTIVATED CARBON ADSORBENT WITH INCREASED HEAT CAPACITY AND THE PRODUCTION THEREOF discloses a method for increasing the heat capacity of activated carbon by adding dense alumina and heating at an elevated temperature
U.S. Pat. No. 4,960,450 (Schwarz) entitled SELECTION AND PREPARATION OF ACTIVATED CARBON FOR FUEL GAS STORAGE discloses a method for making an activated carbon for enhanced sorption of hydrogen by washing the carbon in water or acid and then oxidizing the washed carbon in a stream of oxygen and inert gas at an elevated temperature.
U.S. Pat. No. 4,716,736 (Schwarz) entitled METAL ASSISTED CARBON COLD STORAGE OF HYDROGEN discloses a method for storing hydrogen by using a transition metal dispersed in activated carbon.
U.S. Pat. No. 5,360,461 (Meinzer) entitled POLYMERIC STORAGE BED FOR HYDROGEN discloses a hydrogen storage device using polymeric material and a metal hydride.
U.S. Pat. No. 5,626,637 (Baker) entitled LOW PRESSURE METHANE STORAGE WITH HIGHLY MICROPOROUS CARBONS discloses a method for storing hydrocarbon fuels by making chemically and thermally treating an activated carbon using potassium hydroxide.
U.S. Pat. No. 5,653,951 (Rodriguez) entitled STORAGE OF HYDROGEN IN LAYERED NANOSTRUCTURES discloses a composition comprising a solid layered nanostructure, preferably carbon, for storage of hydrogen.
U.S. Pat. No. 4,857,243 (Von Blucher) entitled PROCESS OF MAKING MICROSPHERULES OF ACTIVATED CARBON discloses a method of making activated carbon microspherules by kneading activated carbon particles of a size below 100 &mgr;m together with a dispersion of a water-insoluble synthetic resin, pressing the mixture through a screen with a mesh size related to the size of the desired product, powdering the pressed material, and granulating and drying the resulting microspherules.
U.S. Pat. No. 4,921,826 (Juntgen) entitled PROCESS FOR PRODUCING AN ACTIVE CARBON CATALYST discloses a process for producing an active carbon catalyst by ammonia treatment of active carbons at a temperature above 350° C. in an inert-gas stream until no SO
2
development occurs.
U.S. Pat. No. 4,371,454 (Hisatsugu) entitled PROCESS FOR PREPARING SPHERICAL CARBON MATERIAL AND SPHERICAL ACTIVATED CARBON discloses a process for preparing spherical activated carbon from an admixture of pitch, amorphous carbon, and a viscosity-controlling agent.
U.S. Pat. No. 4,205,055 (Maire) entitled DUAL PORE-STRUCTURE ARTIFICIAL CARBON AND GRAPHITE discloses a process for making the material and the material itself which is an artificial dual pore-structured carbon suitable for use as a catalyst substrate or an electrode material consisting essentially of a macroporous agglomeration of strongly bonded microporous grains of carbon.
U.S. Pat. No. 5,242,879 (Abe) entitled ACTIVE CARBON MATERIALS, PROCESS FOR THE PREPARATION THEREOF AND THE USE THEREOF discloses an activated carbon tailored for decomposition of hydrogen peroxide, hydrazines, and other water pollutants having an average pore radius between 15 and 30 Å.
U.S. Pat. No. 5,464,605 (Hayden) entitled PROCESS FOR THE DECOMPOSITION AND REMOVAL OF PEROXIDES discloses a process for decomposition and removal of peroxides from a gaseous or liquid media by contacting the media with a carbonaceous char which is made by carbonizing a bituminous coal at temperatures below 700° C. in the presence of an oxidant gas, oxidizing the coal at temperatures below 700° C. during or after the carbonization, and contacting the carbonized coal with a nitrogen compound and raising the temperature above 700° C. The resulting material is then activated to the desired density at temperatures above 700° C. in steam and/or carbon dioxide.
U.S. Pat. No. 5,064,805 (Otowa) entitled PRODUCTION OF HIGH QUALITY CARBON discloses a high quality activated carbon produced by starting with coconut shell char and activating with potassium hydroxide.
U.S. Pat. No. 4,978,649 (Surovikin) entitled POROUS CARBONACEOUS MATERIAL discloses an activated carbon produced by a process that increases the proportion of pores with a size greater than 200 Å.
U.S. Pat. No. 5,837,741 (Schwarz) entitled COMPOSITE MICROPOROUS CARBONS FOR FUEL GAS STORAGE discloses a method of making a microporous carbon material from a precursor which is either a crystalline salt of an aromatic sulfonate or a nonporous polymeric salt.
SUMMARY OF THE INVENTION
Briefly stated, microporous carbonaceous materials, useful in the storage of gaseous fuels such as methane and natural gas. are improved through modification of their microporous structure in a post-carbonization process. This modification is done by heat treatment in an oxidizing atmosphere containing carbon dioxide with or without other diluting gases such as nitrogen, argon or water-vapor. The post-carbonization process involved modifying a starting microporous carbon with heat treatment in which the carbon is contacted with a carbon dioxide-containing atmosphere. This new treatment can be favorably applied either to selected and commercially available activated microporous carbons which have been designed for applications other than fuel gas storage or to synthetic microporous carbons proposed for storage of light gases.
According to an embodiment of the invention, a method for post-carbonization treatment of microporous carbons includes the steps of: (a) providing a specified amount of at least one microporous carbon at room temperature; (b) raising a temperature of said carbon at 10 degrees Celsius per minute from room temperature to approximately 850 degrees Celsius in a first controlled atmosphere; (c) holding said temperature of said carbon at approximately 850 degrees Celsius for a specified period of time in a second controlled atmosphere;
Amankwah Kwabena A. G.
Amato Wayne S.
Contescu Cristian I.
Putyera Karol
Brown, Pinnisi & Michaels P.C.
Hendrickson Stuart L.
Niagara Mohawk Power Corporation
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