Osaka Gas Company Limited

Mitsubishi Jukogyo Kabushiki Kaisha

Other

Takahiro Kasuh

Norihisa Kobayashi

Akinori Yasutake

Isao Mochida

Toshihiko Setoguchi

Masaaki Yoshikawa

Hitoshi Nakamura

Hiroyuki Fujimoto

Akihiro Mabuchi

Katsuhisa Tokumitsu

This invention relates to a technique for removing nitrogen oxides (NO) present in exhaust gases discharged from boilers and the like. When the temperature of the exhaust gas is 100&#xb0; C. or below, a heat-treated active carbon produced by heat-treating a raw active carbon at 600 to 1,200&#xb0; C. in a non-oxidizing atmosphere so as to remove oxygen-containing functional groups present at the surfaces thereof and thereby reduce the atomic surface oxygen/surface carbon ratio to 0.05 or less is preferably used. When the temperature of the exhaust gas exceeds 100&#xb0; C., a heat-treated active carbon produced by heat-treating a raw active carbon at 600 to 1,200&#xb0; C. in a non-oxidizing atmosphere and activating the surfaces thereof with sulfuric acid or nitric acid to impart oxidizing oxygen-containing functional groups thereto is preferably used.

Heat-treated active carbons for use in denitration, processes for producing same, denitration method using same, and denitration system using same

This invention relates to a technique for removing nitrogen oxides (NO) present in exhaust gases discharged from boilers and the like. When the temperature of the exhaust gas is 100&#xb0; C. or below, a heat-treated active carbon produced by heat-treating a raw active carbon at 600 to 1,200&#xb0; C. in a non-oxidizing atmosphere so as to remove oxygen-containing functional groups present at the surfaces thereof and thereby reduce the atomic surface oxygen/surface carbon ratio to 0.05 or less is preferably used. When the temperature of the exhaust gas exceeds 100&#xb0; C., a heat-treated active carbon produced by heat-treating a raw active carbon at 600. to 1,200&#xb0; C. in a non-oxidizing atmosphere and activating the surfaces thereof with sulfuric acid or nitric acid to impart oxidizing oxygen-containing functional groups thereto is preferably used.

An active carbon for use in the treatment of exhaust gas can be obtained by heat-treating a starting active carbon fiber derived from polyacrylonitrile, pitch or the like or a starting particulate active carbon in a non-oxidizing atmosphere. The heat-treating temperature is preferably in the range of 600 to 1,200 &deg; C. for use in the desulfurization of exhaust gas, and in range of 600 to 1,000&deg; C. for use in the denitration of exhaust gas. By using the resulting heat-treated active carbon for the purpose of desulfurization, the sulfur oxide concentration in exhaust gas can be reduced to 5 ppm or below. Moreover, by using the heat-treated active carbon in combination with conventional denitration based on selective catalytic reduction, the nitrogen oxide concentration in exhaust gas can be reduced to 1 ppm or below.

Exhaust gas treating systems

A process for the denitration of combustion exhaust gas from combustion equipment by passing the exhaust gas through an ammonia reduction denitrator, comprises providing a bypass having a low-temperature denitrator installed therein; while the temperature of the exhaust gas is not high enough to allow the ammonia reduction denitrator to function properly, as encountered immediately after starting the combustion equipment, passing the exhaust gas through the bypass to perform the denitration thereof by means of the low-temperature denitrator; when the ammonia reduction denitrator has come to function properly, closing the bypass to perform the denitration of the exhaust gas by means of the ammonia reduction denitrator; and regenerating a catalyst within said low-temperature denitrator while the by-pass is closed.

Exhaust gas denitration method

Carbon material for negative electrode of secondary lithium battery,

Heat-treated active carbons for use in denitration, processes for

An active carbon for use in the treatment of exhaust gas can be obtained by heat-treating a starting active carbon fiber derived from polyacrylonitrile, pitch or the like or a starting particulate active carbon in a non-oxidizing atmosphere. The heat-treating temperature is preferably in the range of 600 to 1,200.degree. C. for use in the desulfurization of exhaust gas, and in range of 600 to 1,000.degree. C. for use in the denitration of exhaust gas. By using the resulting heat-treated active carbon for the purpose of desulfurization, the sulfur oxide concentration in exhaust gas can be reduced to 5 ppm or below. Moreover, by using the heat-treated active carbon in combination with conventional denitration based on selective catalytic reduction, the nitrogen oxide concentration in exhaust gas can be reduced to 1 ppm or below.

Growing community of inventors

Osaka, Japan

Takahiro Kasuh