High-Capacity, Regenerable Sorbent for Removal of Mercury From Flue GasEPA Contract Number: 68D00225
Title: High-Capacity, Regenerable Sorbent for Removal of Mercury From Flue Gas
Investigators: Turchi, Craig S.
Small Business: ADA Technologies Inc.
EPA Contact: Manager, SBIR Program
Project Period: September 1, 2000 through March 1, 2001
Project Amount: $69,995
RFA: Small Business Innovation Research (SBIR) - Phase I (2000) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , SBIR - Air Pollution , Small Business Innovation Research (SBIR)
Description:The Phase I objective is to characterize the different physical attributes of candidate sorbent compounds with regard to mercury uptake and to assess the feasibility of incorporating the new sorbents into a practical treatment system. Mercury is of significant environmental concern because of its toxicity, persistence in the environment, and bioaccumulation in the food chain. Domestic coal-fired power plants emit a total of about 50 metric tons of mercury to the atmosphere annually (approximately 33 percent of all mercury emissions). At present, the injection of carbon-based sorbents is the best candidate technology for reduction of mercury emissions from coal-fired powers plants that do not have wet scrubbers (about 75 percent of all plants). However, this approach is limited by sorbent capacity and flue-gas interactions with the carbon, and it appears that sorbent-to-mercury ratios of 10,000:1 may be required. Carbon injection also may detrimentally impact fly ash quality, making sale of the important by-product more difficult for the utilities.
The proposed work is focused on the characterization and testing of a novel class of sorbents that has shown high affinity for mercury in preliminary laboratory studies. These compounds has been able to adsorb mercury at mass ratios of greater than 1:1 under laboratory conditions. In addition, although the sorbent forms a strong chemical bond with mercury at temperatures typically found with flue gas, the compounds can be thermally regenerated at slightly higher temperatures, allowing for reuse of the sorbent and recovery of mercury for recycling or stabilization through processes already under development at ADA Technologies, Inc.
Inevitably, sorbent performance in flue gas will be poorer than is attained under controlled conditions; however, it is anticipated that the physical structure of these materials will be less prone to interference from other gas components. Unlike activated carbon, which has broad affinity for numerous compounds, members of this class of materials are inert to most chemicals. The sorbents that exhibit favorable properties of high mercury capacity and stability will be tested in simulated flue gas. Optimal methods of deploying the new sorbents will be investigated, including use of fluidized-bed, fixed-bed, or impregnated monolith designs.