Process for regenerating catalyst
AssigneeSeitetsu Kagaku Co., Ltd.
InventorsShigeji Obayashi, Kanji Ueda, Haruhiko Iwatsubo, Thoru Okabe
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Abstract
Catalyst for removing nitrogen oxides, whose activity is lowered by poisoning with sulfur oxides, is contacted with an ammonia gas at a temperature of 200.degree. to 500.degree. C, whereby the sulfur oxides are liberated from the catalyst, and the catalyst is regenerated. Concentration of the ammonia gas to be used in the regeneration treatment must be at least 1% by volume and preferably 5 to 50% by volume of ammonia is used in a mixture with other inert diluting gas. The regenerated catalyst is given an activity as high as that before the poisoning without bringing about any damage and cracking to the catalyst.
Claims16
A process for regenerating a catalyst used for removing nitrogen oxides from flue gas by catalytic reduction with ammonia and wherein said catalyst is an oxide of a metal selected from the group consisting of copper, iron, chromium, vanadium, and mixtures thereof, and said catalyst is poisoned by the formation of sulfates with sulfur oxides contained in said flue gas, which process comprises contacting said poisoned catalyst at a temperature of 350.degree. to 500.degree. C with a gaseous mixture consisting essentially of at least 1% by volume of ammonia and a substantially inert gas and for a time sufficient for regenerating said catalyst to liberate the sulfur oxides thereby from said catalyst, whereby said catalyst is regenerated.
Dependencies are inferred from the claim text.