| 摘要 |
The invention relates to: a ²-type iron silicate which has a fluorine content not more than 400 ppm by weight on a dry basis and in which the crystal grains have a truncated square bipyramidal morphology in an examination with a scanning electron microscope and the whole or part of the iron is contained in the ²-type framework structure, and a process for producing the iron silicate; a ²-type iron silicate which has an SiO 2 /Fe 2 O 3 molar ratio of 50-150, a fluorine content not more than 400 ppm by weight of the dry crystals, and a full width at half maximum of the crystal diffraction (302) plane of 0.16-0.24° and in which the whole or part of the iron is contained in the ²-type framework structure, and a process for producing the iron silicate; and a nitrogen oxide removal catalyst containing a ²-type iron silicate which has iron and aluminum in the ²-type framework structure, has an SiO 2 /Al 2 O 3 molar ratio of 20-70 and an SiO 2 /Fe 2 O 3 molar ratio of 50-200, and has a full width at half maximum of the crystal diffraction (302) plane of 0.30-0.40°, a process for producing the catalyst, and a method for nitrogen oxide removal with the catalyst. |
