A process for optimizing the removal of nitrogen oxide (NO.sub.x) and sulfur oxide (SO.sub.X) from flue gases is provided in which the flue gases pass over a lanthanide-oxygen-sulfur catalyst. The catalyst has active sites provided on its surface which promote the dissociation of NO.sub.X and receive and entrap oxygen released during the dissociation of the NO.sub.X. While the flue gases pass over the catalyst, a reducing gas contacts the catalyst to reduce the oxygen on the active sites of the catalyst and permit the catalyst to continue to promote the dissociation of the NO.sub.x in the flue gas. If the flue gases contain SO.sub.X, they are then passed over a solid solution having a solvent of a first lanthanide oxide compound which crystallizes in the fluorite habit and a solute of at least one altervalent oxide of a second lanthanide. The SO.sub.X in the flue gases reacts with the solid solution to form a sulfated lanthanide oxide which is removed from the flue gases. The sulfated lanthanide oxide may then be dissociated by raising its temperature to regenerate the lanthanide oxide.
BACKGROUND OF THE INVENTION
Field of the Invention
This application is a continuation-in-part of copending application, U.S. Ser. No. 290,392, filed Dec. 29, 1988, now abandoned, which was a continuation in part of patent application 100,291 filed Sep. 23, 1987 now U.S. Pat. No. 4,885,145 which was a continuation-in-part of application Ser. No. 846,272 filed Mar. 31, 1986, now U.S. Pat. No. 4,714,598, which was a division of application Ser. No. 718,989 filed Apr. 2, 1985 now U.S. Pat. No. 4,604,268, which was a continuation-in-part of application Ser. No. 521,751 filed Aug. 8, 1983, now U.S. Pat. No. 4,507,149 which was a continuation-in-part of application Ser. No. 471,773 filed Mar. 3, 1988, now abandoned which was a continuation of application Ser. No. 174,024 filed Jul. 31, 1980 now U.S. Pat. No. 4,397,683.
The present invention provides novel catalysts for the simultaneous removal of SO.sub.2 and NO.sub.x from flue gases. The catalysts may be supported or unsupported, pretreated or untreated, but allow the simultaneous reduction of SO.sub.2 to S and NO.sub.x to N.sub.2. Elemental sulfur is a useful byproduct of the process.
A low sidestream smoke cigarette comprises a conventional tobacco rod, and a combustible treatment paper having a sidestream smoke treatment composition. The treatment composition comprises in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct for said catalyst.
The present invention provides compositions including a salt selected from the group consisting essentially of sodium nitrate, sodium nitrite, ammonium nitrate, lithium nitrate, barium nitrate, cerium nitrate, and mixtures thereof, as flue gas conditioning formulations for use in controlling particulates, hazardous substances, NO.sub.x, and SO.sub.x. For the purpose of obtaining greater yields of particulate and hazardous substance removal, the compositions may further include a polyhydroxy compound, preferably selected from the group consisting essentially of sucrose, fructose, glucose, glycerol, and mixtures thereof. Methods are also provided for adding these compositions to the flue gas stream to control particulate, hazardous substance, NO.sub.x, and SO.sub.x emissions.
