| 摘要 |
Provided are an ferrosilicate catalyst, which has catalytic performance of efficiently reducing nitrogen oxides in a relatively low temperature range of not higher than 250 deg.C and superior hydrothermal durability as compared to conventional catalysts, and a process for reducing nitrogen oxides using the catalyst. A catalyst for reducing nitrogen oxides is a crystalline silicate containing iron in beta-framework structure in which a SiO2/Fe2O3 mol ratio is in the range of 20 to 300 and at least 80% of the contained iron is an isolated iron ion Fe^3+. A process for reducing nitrogen oxides comprises the step of reacting nitrogen oxides with at least one reducing agent consisting of ammonia, urea and an organic amine in the presence of the catalyst for reducing nitrogen oxides to selectively restore the nitrogen oxides.
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