Abstract: The present invention relates to a process for removing nitrogen oxides contained in a gaseous mixture such as combustion flue gas, etc. by reduction of the nitrogen oxides with ammonia, and a cuprous or cupric halide is used as a catalyst to carry out the reduction in a low temperature range. As a result, nitrogen oxides can be satisfactorily removed by the reduction even at about 150.degree. C.

Abstract: Nitrogen oxides (NOx) are removed from combustion waste gases by injecting gas (NH.sub.3) into the combustion waste gases in the presence of a metallic catalyst to deoxidize the nitrogen oxides to nitrogen and water, within a reaction tower having the catalysts moving through the reaction tower, so that thereafter the dust may be separated from the catalysts and the catalysts may be regenerated continuously, so that the regenerated catalysts may be returned to the reaction tower. The catalyst moves in a substantially closed path, and preferable downwardly through the reaction tower, with the ammonia gas and combustion waste gases moving in cross current through the reaction tower, with mixing being enhanced by a plurality of angled baffle plates.

Abstract: An active carbon suspension obtained by mixing particles of active carbon with water, and flue gas containing sulfur dioxide are introduced into a desulfurization column, wherein the flue gas is contacted with the active carbon suspension. Sulfur dioxide is absorbed into the active carbon suspension, thereby purifying the flue gas. On the other hand, the absorbed sulfur dioxide is converted to sulfuric acid by a catalytic action of the active carbon in the desulfurization column, and the resulting sulfuric acid is separated from the active carbon suspension.

Abstract: A contaminant, such as sulfur dioxide, is removed from a fluid, such as hot exhaust gas, by passing it through beds of material for removing the contaminants, such as activated carbon for adsorbing the sulfur dioxide as sulfur trioxide; periodically, the bed is regenerated by discontinuing the passage of process fluid therethrough and passing through the bed a regenerating fluid, such as water, with quantities of the regenerating fluid being successively passed through the bed with corresponding decreasing amounts of contaminants, such as sulfuric acid within the water, in the respective quantities of regenerative fluid. At least one further bed of material is regenerated with substantially the same regenerative fluid in substantially the same succession of concentrations, but out of phase so that a quantity of regenerative fluid of one contaminant concentration is passed completely through only one bed of material prior to its passing through another bed of material.