Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Reexamination Certificate
2000-02-29
2001-05-01
Griffin, Steven P. (Department: 1754)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
C423S244060, C423S244070, C423S244100, C502S034000, C502S053000, C502S224000, C502S345000, C502S415000, C502S517000
Reexamination Certificate
active
06224840
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a &ggr;-Al
2
O
3
sorbent impregnated with alkali salt and CuO, more specifically, to a &ggr;-Al
2
O
3
sorbent impregnated with alkali salt and CuO, which has a superior SO
2
sorption capacity and a high regeneration conversion rate.
BACKGROUND OF THE INVENTION
Sulfur dioxide(SO
2
) exhausted from combustion of fossil fuel pollutes air and acid rain containing SO
2
causes soil and water pollution. Accordingly, removal of SO
2
before emitting flue gas into the atmosphere has been regarded as an important matter, as the consumption of fossil fuel increases.
For the removal of SO
2
, the following two methods have been suggested in the art: one is to prevent the generation of SO
2
itself by desulfurizing the fossil fuel prior to the combustion; and, the other is to remove SO
2
from the flue gas using appropriate sorbents, which can be further classified into dry method and wet method depending on the type of sorbent.
In accordance with the wet method, SO
2
is directly taken up by liquid sorbents such as water, alkali solution, which facilitates efficient removal of SO
2
with relatively inexpensive sorbents. However, the problem of disposal of wastes such as solid materials produced from the reaction with SO
2
and waste water remains unsolved.
On the other hand, in accordance with the dry method, SO
2
is removed by solid sorbent whose surface area is relatively large. This method has several advantages over the wet method that: no waste occurs and the expenses for equipment and operation may be cut down, since the sorbent can be regenerated and reused; and, the pure SO
2
produced from the regeneration step can be utilized as pure sulfur or sulfuric acid after appropriate treatment. However, it has revealed a shortcoming that sulfur removal efficiency is extremely low, since SO
2
is reacted with the sorbent for a relatively short time period compared with the wet method.
Naturally, many studies have focused on the development of a novel sorbent employed for dry method, which has a high SO
2
sorption capacity. For example, Centi et al. discloses a &ggr;-Al
2
O
3
sorbent impregnated with metal oxides (see: Centi et al., Ind. Eng. Chem. Res., 31:1947(1992)), where SO
2
is taken up by the sulfation of the metal oxides to give metal sulfides. Among the metal oxides, copper oxide(CuO) has been used as the most promising one, since it reacts with SO
2
rapidly and has a relatively high SO
2
removal capacity. However, the prior art sorbent is proven to be less satisfactory in the sense that the SO
2
removal capacity is not sufficient enough to be realized in industrial application. Under the circumstances, there are strong reasons for developing an alternative sorbent which has a superior sulfur removal capacity and a high regeneration conversion rate.
SUMMARY OF THE INVENTION
The present inventors have made an effort to improve the sulfur removal capacity and regeneration conversion rate of the conventional sorbents, and finally discovered that: the SO
2
sorption capacity of the sorbent can be improved by additional impregnation of alkali salt promoter into the conventional CuO/&ggr;-Al
2
O
3
sorbent, since the alkali salt promoter causes the &ggr;-Al
2
O
3
carrier to coparticipate in the desulfurization reaction with CuO catalyst.
A primary object of the invention is, therefore, to provide a &ggr;-Al
2
O
3
sorbent impregnated with alkali salt and CuO, which has a superior SO
2
sorption capacity and a high regeneration conversion rate.
The other object of the invention is to provide a process for preparing the &ggr;-Al
2
O
3
sorbent impregnated with alkali salt and CuO.
REFERENCES:
patent: 3957952 (1976-05-01), Naber et al.
patent: 4323544 (1982-04-01), Magder
patent: 4382021 (1983-05-01), Laurer et al.
Yoo et al., Sulfation of A12O3 in Flue Gas Desulfurization by CuO/gamma-Alumina Sorbent, Ind. Eng. Chem. Res., 1994, 33, pp. 1786-1791.*
Jeong et al., Enhancement of the SO2 Sorption Capacity of CuO/gamma-Alumina Sorbent by an Alkali-Salt Promoter, Ind. Eng. Chem. Res., 1997, 36, pp. 5425-5431.
Jeong Sang-Mun
Kim Sang-Done
Yoo Kyung-Seun
Griffin Steven P.
Ildebrando Christina
Knobbe Martens Olson & Bear LLP
Korea Advanced Institute of Science and Technology
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