| Project Information |
| Project ID: | DE-FG26-99FT40582 |
| Project Title: | Study of the Activation of Coal Chars |
| FE Program: | Adv. Research - University/National Laboratory R&D |
| Research Type: | Applied Research |
| Funding Memorandum: | Other Federal Assistance |
| Project Performer |
| Performer Type: | Private Higher Educational Institution |
| Performer: | Brown University
Brown University
(Waterman Street) |
| Project Team Members: |
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| Project Location |
| City: | Providence |
| State: | Rhode Island |
| Zip Code: | 02912-0001 |
| Congressional District: | 02 |
| Responsible FE Site: | NETL |
| Project Point of Contact |
| Name: | Suuberg, Eric M. |
| Telephone: | (401) 863-1420 |
| Fax Number: | |
| Email Address: | |
| Fossil Energy Point of Contact |
| Name: | Read, Richard B. |
| Telephone: | (412) 386-5721 |
| Location: | NETL |
| Email Address: | richard.read@netl.doe.gov |
| Project Dates |
| Start Date: | 06/30/1999 |
| End Date: | 12/31/2003 |
| Contract Specialist |
| Name: | Mitchell, Cynthia Y. |
| Telephone: | (412) 386-4862 |
| Cost & Funding Information |
| Total Est. Cost: | $217,925 |
| DOE Share: | $190,925 |
| Non DOE Share: | $27,000 |
| Project Description |
There are two intrinsic determinants of performance of a given carbon. The first is the nature of its porosity, which is the main feature of interest in the present proposal. The second is the nature of its surface. Regarding this second point, the nature of the oxygen functional groups on the carbon surface is key. Depending upon the type of groups present, the surface can behave in an amphoteric manner - either as an acid or basic adsorbent, which in turn favors adsorption of appropriately interacting adsorptives. The presence of mineral impurities can also significantly affect the behavior of the surface. The porosity may sometimes be related to the presence of surface oxides on the carbon.
The proposed project approach involves the use of a combination of adsorption techniques which are now accepted by the activated carbon community as providing reliable characterization of the porosity of carbons. This will involve combined use of nitrogen and carbon dioxide adsorptives. In the proposed program of study, the activation of the Argonne Premium coal set will be examined as a function of pyrolysis conditions (temperature and heating rate), mineral content, and activation conditions (gaseous environment, temperature). The activating gases which will be examined include oxygen, carbon dioxide, nitric oxide, and steam. The intent is to develop a clearer understanding of how the above factors influence development of porosity with burn-off. It is also proposed that a study be conducted into when the micropores are accessible to activating agents and when not. This will employ a chemisorption-based technique.
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| Project Background |
The U.S. production capacity for activated carbons is 146,000 tons per annum, and the total world capacity is more than 2.5 times this value1. The estimated growth in the market is 5.5% per annum, not taking into account any major new applications, such as for gas storage.
There is an enormous range of carbons presently on the market - not all activated carbons are appropriate for all tasks. Currently, activated carbons are produced from a large variety of starting materials- hard and soft woods, nutshells, sugar, coal, and man-made polymers. All have unique properties, which derive in large measure from the starting material, but which can also be strongly influenced by the nature of the processing they receive.
There are two intrinsic determinants of performance of a given carbon. The first is the nature of its porosity, which is the main feature of interest in the present proposal. The second is the nature of its surface. Regarding this second point, the nature of the oxygen functional groups on the carbon surface is key. Depending upon the type of groups present, the surface can behave in an amphoteric manner - either as an acid or basic adsorbent, which in turn favors adsorption of appropriately interacting adsorptives. The presence of mineral impurities can also significantly affect the behavior of the surface. The porosity may sometimes be related to the presence of surface oxides on the carbon. For example, the smallest microporosity in a carbon can sometimes be partially blocked by the presence of oxides on the carbon surface.
Generally raw carbons require a process termed ôactivationö to reach commercially interesting surface areas of the order 1000 m2/g. The surface area is present in fine porosity in the carbon. High surface areas are required for high sorptive capacities in the carbon. In industrial practice, so-called physical activation generally involves burning off some of the raw carbon in oxidizing gas, so as to create the fine porosity and surface area. The usual commercial choices of gas for activation are steam, air or CO2, or their mixtures. Activation normally takes place at temperatures between 700 |C and 1000|C in steam and CO2 activation, and lower for pure air. There is also a second category of activation procedures termed ôchemicalö activation. These procedures, which involve addition of materials such as zinc salts or phosphoric acid to the carbon precursors, will not be considered here.
It is important to note that the porosity of the carbon is largely determined by the combination of starting material and pyrolysis conditions; subsequent activation only serves to ôopen upö the porosity2. There appears to be, in many cases, a pre-activation maximum in the surface area, and micropore volume, near a pyrolysis temperature of 700|C2.
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| Project Milestones |
| This information is currently unavailable. |
| Project Accomplishments |
