Cooper, Dunham, Clark, Griffin & Moran
Catalyst for reducing nitrogen oxides in a waste gas and a process for catalytically reducing nitrogen oxides contained in a waste gas
 The present invention relates to a catalyst comprising at least a metal salt of heteropoly-acid, which is composed of a sort of heteropoly-acid and one or more metals selected from a group of the first transition metals of the periodic table. The catalyst of the present invention exhibits high activity and selectivity in the catalytic reduction of nitrogen oxides with ammonia at a temperature of from 250.degree. to 550.degree. C. and offers high resistivity to the poisonous effect of sulfur oxides. It does not entail a wasteful use of the reducing agent, because the catalyst of the present invention does not accelerate the reaction of the reducing agent such as ammonia with oxygen coexisting in the waste gas to be treated, which results in the elimination of the undesired excessive consumption of the reducing agent. Therefore, this invented catalyst may provide a commercially advantageous process for removing harmful constituents, nitrogen oxides from a waste gas which contains the same and additionally, in some cases, sulfur dioxides. 
JGC Corporation
B Y B
B01D Y10S B01J
inventional additional inventional
Tadashi Toshihiro Keiichiro Fusao Katsuhiko Takehiko Katsuaki Kintaro Noriyuki Tsutomu Tomiaki
Asanabe Ueno Watanabe Nishida Adachi Takeda Ohsato Tsuda Suzuki Yanagihara Yamada