DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS
The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly fly ash containing unburned carbon. However, the carbonaceous residue in fly ash, unburned carbon (UC), is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, this research program focuses on the development of activated carbons from the unburned carbon present in fly ash. During the present reporting period (June 30, 1999--June 29, 2000), Task 1 ''Procurement and characterization of CCBPs'' was initiated and samples from various combustion systems were collected. The suite assembled thus far includes samples from pulverized utility boilers with low-NOx burners and Selective Non Catalytic Reduction system, and also from an utility cyclone unit. The characterization studies showed that the sample from the cyclone unit contained the highest carbon content (LOI of {approx} 80%), since this unit has been retrofitted with a technology to separate the unburned carbon from the fly ash. In contrast, the sample from the unit retrofitted with a Selective Non Catalytic Reduction system showed the lowest carbon content with LOI values around 2-4%. The samples from the utility boilers with low-NOx burners were collected from the hot-side hoppers and present carbon contents {approx} 50%. The BET (N{sub 2} 77K) surface areas of the samples investigated were between 30-40 m{sup 2}/g and the pore volume is mainly due to mesopores. In addition, during this reporting period, also Task 2 ''Development of activated carbons'' and Task 3 ''Characterization of activated carbons'' were initiated. The investigations showed that after steam activation at 850 C, the unburned carbon samples generated activated carbons with microporous structure and surface areas up to 443 m{sup 2}/g. The samples activated with steam present generally higher surface areas than those using CO{sub 2} or KOH pretreatment, probably due to the faster reaction rate of steam. The activation process could tailor the inherent mesoporosity of these materials into the desired porosity for a specific application, since the mesophore volume accounted for {approx} 66% of the total pore volume for the parent samples, while after steam activation the micropore volume accounted for over 60% of the total.
- Research Organization:
- The Pennsylvania State University (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FG26-99FT40593
- OSTI ID:
- 818152
- Resource Relation:
- Other Information: PBD: 31 Jul 2000
- Country of Publication:
- United States
- Language:
- English
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DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS
DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS