Babcock-hitachi Kabushiki Kaisha

Mitsubishi Hitachi Power Systems, Ltd.

Seiji Ikemoto

Yasuyoshi Kato

Keiichiro Kai

To provide a catalyst having excellent performance and durability by improving a NOx reduction ratio at 350&#xb0; C. or higher without deteriorating excellent durability of a Ti&#x2014;V&#x2014;Mo&#x2014;P catalyst in view of problems of conventional art. A NOx reduction catalyst for exhaust gas, which is composed of a catalyst composition that comprises titanium (Ti), an oxide of phosphorous, molybdenum (Mo) and/or tungsten (W), oxide of vanadium (V), and high-silica zeolite that has an SiO/AlOratio of not less than 20 is obtained by kneading in the presence of water, drying and calcining (1) titanium oxide, and phosphoric acid or an ammonium salt of phosphoric acid in an amount of more than 1% by weight and not more than 15% by weight relative to the titanium oxide in terms of HPO, (2) an oxo acid or oxo acid salt of molybdenum (Mo) and/or tungsten (W) and an oxo acid salt of vanadium (V) or vanadyl salt respectively in an amount of more than 0% by atom and not more than 8% by atom relative to the titanium oxide and (3) high-silica zeolite in an amount of more than 0% by weight and not more than 20% by weight relative to the titanium oxide.

NOx reduction catalyst for exhaust gas and method for producing same

Provided is a method for cleaning a used denitration catalyst, which prevents release of mercury to the atmosphere by collecting and removing mercury which would have been released to the atmosphere in the process of cleaning the used denitration catalyst. The method comprises immersing the used denitration catalyst mainly composed of titanium oxide and having been used in exhaust gas containing mercury in a cleaning liquid, and stirring the cleaning liquid to dissolve and remove catalyst poisons including the mercury from the used denitration catalyst, wherein a waste gas generated in the step of stirring the cleaning liquid is conducted to a flue having a mercury removal device so as to remove the mercury, and then vented to the atmosphere.

Method for cleaning used denitration catalyst

A method for removing mercury in a combustion exhaust gas includes injecting ammonia or urea as a reducing agent into a combustion exhaust gas containing nitrogen oxides, sulfur dioxide, metallic mercury, and hydrogen halides, and then introducing the combustion exhaust gas to a denitration apparatus filled with a denitration catalyst to cause a denitration reaction and oxidize the metallic mercury to produce mercury halide; and introducing the combustion exhaust gas through an air preheater and an electric dust collector to a wet desulfurization apparatus, thereby removing sulfur dioxides and the mercury halide, wherein the ammonia concentration of the combustion exhaust gas at an exit of the denitration apparatus is maintained at 5 ppm or higher, and the mercury halide is adsorbed or precipitated onto combustion ash and collected by the electric dust collector to discharge the mercury halide out of a system.

Growing community of inventors

Kure, Japan

Seiji Ikemoto