Abstract: This invention relates to a technique for removing nitrogen oxides (NO.sub.x) present in exhaust gases discharged from boilers and the like. When the temperature of the exhaust gas is 100.degree. C. or below, a heat-treated active carbon produced by heat-treating a raw active carbon at 600 to 1,200.degree. 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.degree. C., a heat-treated active carbon produced by heat-treating a raw active carbon at 600 to 1,200.degree. 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.

Abstract: 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.

Abstract: A method of denitrating an exhaust gas by means of removing nitrogen oxides catalytically using ammonia as a reducing agent while introducing an exhaust gas containing the nitrogen oxides into a reaction vessel packed with a catalyst, comprising:providing a denitration catalyst layer in the upstream of the gas flow, an ammonia decomposition catalyst layer capable of decomposing oxidatively ammonia into nitrogen and nitrogen oxides in the downstream and a second denitration catalyst layer or a denitration catalyst layer capable of decomposing ammonia in the further downstream; and,adding ammonia in an amount not less than the reaction equivalence for the nitrogen oxides in the exhaust gas to the inlet of the first denitration catalyst layer.

Abstract: For a system having a source of nitrogen oxide-containing gas, an ammonia reduction denitrator, and a leak ammonia recovery unit which adsorbs and removes ammonia escaping from said ammonia reduction denitrator, a method of removing adsorbed ammonia from said leak ammonia recovery unit and reusing the removed ammonia is provided which includes the steps of: introducing hot exhaust gas discharged from said nitrogen oxide-containing gas source into said leak ammonia recovery unit to desorb ammonia therefrom; after desorption of ammonia, cooling said heated leak ammonia recovery unit with cool air; and feeding ammonia carried away by said hot exhaust gas and said cool air to an upstream side of said ammonia reduction denitrator or to the source of nitrogen oxide-containing gas.

Abstract: An exhaust gas purifying apparatus, which is intended to improve hydrocarbon purifying performance and simplify the after-treatment of adsorbed hydrocarbon, an in which a three way valve 51 is operated under the control of a controller 80 to cause a bypass exhaust gas passage 30 to be communicated with a main exhaust gas passage, so that hydrocarbon in exhaust gas is adsorbed onto an adsorption catalyst 40 when the temperature of a three way catalyst 20 in the main exhaust gas passage 13 is low. When the three way catalyst temperature increases, the bypass exhaust gas passage is shut off from the main exhaust gas passage by the three way valve and the adsorption catalyst is heated by a heater 60, so that the adsorbed hydrocarbon is oxidized at the adsorption catalyst to form a harmless substance.

Abstract: A method of denitrating an exhaust gas by means of removing nitrogen oxides catalytically using ammonia as a reducing agent while introducing an exhaust gas containing the nitrogen oxides into a reaction vessel packed with a catalyst, comprising:providing a denitration catalyst layer in the upstream of the gas flow, an ammonia decomposition catalyst layer capable of decomposing oxidatively ammonia into nitrogen and nitrogen oxides in the downstream and a second denitration catalyst layer or a denitration catalyst layer capable of decomposing ammonia in the further downstream; and,adding ammonia in an amount not less than the reaction equivalence for the nitrogen oxides in the exhaust gas to the inlet of the first denitration catalyst layer.

Abstract: An apparatus installed between a fuel economizer and an air preheater for the denitration of exhaust gas from a coal-fired boiler includes at least one vertical flue situated upstream of a reactor containing a denitration catalyst to cause an upward flow of the gas, A hopper is located below the vertical flue for collecting ash separated from the gas, A baffle is preferably provided in the flue to ensure the still more effective separation of ash from a gas.

Abstract: This invention relates to a catalyst for purifying an exhaust gas, which has a denitrification property in the lean atmosphere and good durability and is hardly deteriorated even in a high temperature rich atmosphere. The feature thereof consists in a catalyst for purifying an exhaust gas, comprising a crystalline silicate having the specified X-ray diffraction pattern and a chemical composition represented by the following chemical formula in the term of mole ratios of oxides under dehydrated state,(1.+-.0.8)R.sub.2 O.?aM.sub.2 O.sub.3.bM'O.cAl.sub.2 O.sub.3 !.ySiO.sub.2in which R is at least one of alkali metal ions and hydrogen ion, M is at least one elementary ion selected from the group consisting of Group VIII elements of Periodic Table, rare earth elements, titanium, vanadium, chromium, niobium, antimony and gallium, M' is an alkaline earth metal ion selected from magnesium, calcium, strontium and barium ions, a>0, 20>b.gtoreq.

Abstract: To achieve a high degree of heat recovery by decomposing surplus ammonia present on the downstream side of a denitrator in an exhaust gas boiler while preventing the deposition of acid ammonia sulfate on low temperature heating tubes, an exhaust gas boiler includes a residual ammonia decomposer which is disposed at a location downstream of the denitrator and between two divided high pressure evaporators.

Abstract: A method for the denitration of exhaust gas from a gas turbine or an internal combustion engine which comprises (a) reducing a part of the NO.sub.2 constituting NO.sub.x contained in the exhaust gas to NO by means of a reduction catalyst bed for reducing NO.sub.2 to NO, the reduction catalyst bed being installed in flow communication with the exhaust gas outlet of the gas turbine or internal combustion engine, and (b) injecting NH.sub.3 into the exhaust gas within an exhaust heat recovery unit and then decomposing and removing NO.sub.x contained in the exhaust gas and now composed chiefly of NO, by means a denitration catalyst bed installed within the exhaust heat recovery unit to effect the catalytic reduction of NO.sub.x with NH.sub.3.

Abstract: The gasification-combined power plant of the present invention has a structure wherein a fuel gas is generated by partially oxidizing a carbon-containing fuel 2 with an oxygen-containing gas 3 in the gasification apparatus 1, the sensible heat of the fuel gas is recovered by the heat exchanger 4, char and dust are removed from the fuel gas by the dust collector 5, trace gas components, such as H.sub.2 S and NH.sub.3, are simultaneously removed from the waste gas by the gas separation apparatus 6 based on dry physical adsorption of these components (for example, by a pressure swing adsorption method), the thus separated and removed gas containing high concentrations of trace gas components, such as H.sub.2 S and NH.sub.3, is denitrated and desulfurized by the gas disposal apparatus 7 and then is discharged from the chimney 13 into the atmosphere.

Abstract: A catalyst for exhaust gas purification having a crystalline silicate including an oxide of an alkali metal and/or hydrogen ion, aluminum oxide, an oxide of an alkaline earth metal, Ca, Mg, Sn, or Ba, an X-ray diffraction pattern described in Table 1 in the specification, and containing at least one metal from the group consisting of the elements in Groups Ib and VIII of the periodic table, rare earth elements, titanium, vanadium, chromium, antimony, zinc, and manganese. With the use of a crystalline silicate containing alkaline earth elements together with other metals or with a composite structure of catalyst, the separation of aluminum or other metals from the crystal lattices (dealuminization or demetallization) can be controlled, and heat and steam resistance may be achieved.

Abstract: The gasification-combined power plant of the present invention has a structure wherein a fuel gas is generated by partially oxidizing a carbon-containing fuel 2 with an oxygen-containing gas 3 in the gasification apparatus 1, the sensible heat of the fuel gas is recovered by the heat exchanger 4, char and dust are removed from the fuel gas by the dust collector 5, trace gas components, such as H.sub.2 S and NH.sub.3, are simultaneously removed from the waste gas by the gas separation apparatus 6 based on dry physical adsorption of these components (for example, by a pressure swing adsorption method), the thus separated and removed gas containing high concentrations of trace gas components, such as H.sub.2 S and NH.sub.3, is denitrated and desulfurized by the gas disposal apparatus 7 and then is discharged from the chimney 13 into the atmosphere.

Abstract: Here is provided an adsorbent for adsorbing and removing an arsenic compound which becomes a catalyst poison in a selective contact reduction process for removing nitrogen oxides (NOx) from a combustion exhaust gas by the use of an ammonia as a reducing agent and a denitrating catalyst.The adsorbent of the present invention comprises a material in which the total volume of pores is 0.2 to 0.7 cc/g and the volume of the pores having a pore diameter of 300 .ANG. or more is 10% or more with respect to the total pore volume, and the material is a specific element, its oxide, an ion-exchanged zeolite or the like.In addition, the present invention is directed to a method for removing the arsenic compound from the combustion exhaust gas by injecting the adsorbent into the flow of the gas on the upstream side of the denitrating catalyst.

Abstract: The present invention is directed to a method for treating an exhaust gas containing dust composed of a glassy material and a sticky material consisting principally of CaO in a gas parallel flow type solid-gas contact reactor, the aforesaid method being characterized by including the step of forcing the dust to collide with a solid surface on the upstream side of the reactor in order to separate the dust into the glassy material and the sticky material consisting principally of CaO; and the present invention is also directed to an apparatus for the above method, the apparatus being characterized by including a collision device for colliding with the dust which is disposed in an exhaust gas flow path on an upstream side of the reactor.

Abstract: A method for regenerating a denitration catalyst for exhaust gases discharged from coal-burning apparatus, in which a used catalyst whose denitration performance has lowered is contacted with fluidized abrasive particles. As a result, catalyst poisons deposited on the catalyst surface are removed by abrasive contact.

Abstract: Cyanometallophthalocyanine crystals which are organic electroconductive crystals are produced by electrolysis of an electrolyte containing an alkali salt of dicyanometallophthalocyanine. Organic electroconductive crystals of better quality are produced by causing the cyanometallophthalocyanine crystals mentioned above to incorporate therein an electron accepting compound and an electron donating compound as doping substances.

Abstract: A denitration catalyst comprising at least three metal components, (A) titanium, (B) tungsten and/or magnesium, and (C) vanadium, the titanium and tungsten being contained as oxides and the magnesium and vanadium being contained in the form of an oxide or a sulfate or both, said catalyst being composed of a porous molded article of a mixture of an oxide of component A and an oxide and/or a sulfate of component B, the atomic ratio of component B to component A being from 0.01 to 1, and a vanadium compound localized in that area of said molded article which extends from its outermost surface to a depth of 500 microns or less, the content of the vanadium compound in said area being 0.1 to 15% by weight; and a method for removing nitrogen oxides from a waste gas, which comprises contacting a waste gas containing nitrogen oxides, together with ammonia and molecular oxygen, at a temperature of 150.degree. to 650.degree. C., with the aforesaid catalyst.