Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Nitrogen or nitrogenous component
Patent
1997-10-08
1999-08-10
Straub, Gary P.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Nitrogen or nitrogenous component
423240S, 42324407, 42324408, B01D 5350, B01D 5356, B01D 5360, B01D 5368
Patent
active
059355395
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This application is the National Stage filing under 35 U.S.C. .sctn.371 of International Application No. PCT/EP95/03430 filed Aug. 31, 1995, and incorporated herein by reference.
The invention relates to the purification of gases contaminated by nitric oxide, in particular to the purification of smoke generated by the combustion of a fuel in the presence of air.
TECHNOLOGY REVIEW
Smoke generated by the combustion of gaseous, liquid or solid combustible materials is usually contaminated by nitrogen oxides arising from atmospheric nitrogen and, if appropriate, from nitrogenous compounds present in the fuel. In this smoke, most of the nitrogen oxides are composed of nitric oxide (NO), the balance being mainly composed of nitrogen dioxide (NO.sub.2).
The high toxicity of nitric oxide and nitrogen dioxide and their contribution to the formation of acid rain imply removing them from smoke before discharging the latter to the atmosphere.
U.S. Pat. No. 4,783,325 provides a two-stage process for purifying a gas containing nitric oxide. In a first step, a gas mixture containing oxygen and an initiator of perhydroxyl radicals is introduced into the gas to be purified, which is maintained at high temperature, so as to oxidize the nitric oxide to nitrogen dioxide; in a second step, the gas collected from the first step is treated with lime, sodium carbonate, sodium bicarbonate or sodium sesquicarbonate, in order to decompose the nitrogen dioxide. In this known process, the gas compound which is the initiator of perhydroxyl radicals can be a vaporized hydrocarbon or gaseous hydrogen peroxide. This known process implies that two different reactants are introduced separately and successively into the gas to be treated, which complicates its implementation and requires expensive equipment. The use of a gaseous reactant complicates the execution of the process still more.
In order to purify a gas from nitrogen dioxide, the suggestion has also been made to subject it to washing by means of an alkaline solution of hydrogen peroxide or of a peroxide compound such as sodium perborate or percarbonate (Japanese Patent Application JP-A-51006884). This process, however, does not relate to the purification of a gas contaminated by nitric oxide. Moreover, it has the disadvantage of requiring complex and expensive equipment for carrying out washing of the gas to be purified with the aqueous alkaline solution.
It has also been proposed to introduce sodium percarbonate or sodium perborate into a cigarette filter, in order to remove nicotine, carbon monoxide, nitric oxide and nitrogen dioxide from the smoke (Japanese Patent Application JP-A-57018974).
The invention is targeted at providing a solid reactive composition which makes possible efficient purification of a gas contaminated by nitric oxide, while avoiding the disadvantages of the known processes described above.
SUMMARY OF THE INVENTION
The invention consequently relates to a pulverulent solid reactive composition for purifying, from nitric oxide, a gas containing nitric oxide, the said composition comprising a mixture composed of at least one solid peroxide compound and of at least one alkali metal salt selected from alkali metal carbonates, alkali metal bicarbonates, and alkali metal carbonate and alkali metal bicarbonate solid solutions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the amount of NO removed out of smoke using sodium percarbonate powder.
FIG. 2 shows the amount of NO.sub.x removed out of smoke using sodium percarbonate powder.
FIG. 3 shows the amount of HCl removed out of smoke using sodium percarbonate powder.
FIG. 4 shows the amount of SO.sub.2 removed out of smoke using sodium percarbonate powder.
FIG. 5 shows the amount of NO removed out of smoke using sodium bicarbonate powder.
FIG. 6 shows the amount of NO.sub.x, removed out of smoke using sodium bicarbonate powder.
FIG. 7 shows the amount of HCl removed out of smoke using sodium bicarbonate powder.
FIG. 8 shows the amount of SO.sub.2 removed out of smoke
REFERENCES:
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patent: 4783325 (1988-11-01), Jones
patent: 4908195 (1990-03-01), Wanner et al.
patent: 5118480 (1992-06-01), Cook et al.
patent: 5186914 (1993-02-01), Yoshihiro et al.
patent: 5540902 (1996-07-01), De Soete
Schneller John W.
Solvay ( Societe Anonyme)
Straub Gary P.
Vanoy Timothy C
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