Babcock-hitachi Kabushiki Kaisha

Kunihiko Konishi

Yasuyoshi Kato

Toshiaki Matsuda

Nobue Teshima

Hiroshi Akama

Ikuhisa Hamada

Fumito Nakajima

Nobuyoshi Ishida

Naomi Yoshida

Masao Ohta

Hitoshi Yamasaki

Yoshihide Kondo

Hiroyuki Kamio

Masahiro Nitta

Yuji Fukuda

Taiji Kamiguchi

Isato Morita

Tadaaki Mizoguchi

Meiji Ito

A catalyst for purifying an exhaust gas includes a first component having activity for reducing nitrogen oxides with ammonia and a second component having at least one of activity for forming nitrogen oxide from ammonia and activity for forming carbon dioxide from carbon monoxide. The first component is a composition containing an oxide of at least one member selected from titanium, vanadium, tungsten and molybdenum and the second component is a composition containing a salt of a noble metal selected from platinum, palladium and rhodium or any one of these noble metals supported on a porous material selected from zeolites, alumina and silica. The invention further provides a method for purifying an exhaust gas containing NOx, CO and leak NH.sub.3 using the catalyst.

Catalyst for purifying exhaust gas

NOx removal catalyst can be obtained by kneading various kinds of inorganic fibers and water containing a surfactant to make a pulp-like substance, adding a catalytic component thereto and then further kneading the resultant mixture to prepare a catalyst paste. The thus obtained catalyst paste is shaped into a honeycomb-like, plate-like or column-like form according conventional various molding methods, and then dried and calcined for use. Instead of the above catalytic components; catalytic carriers such as titanium, zeolite, zirconia and the like may be shaped and calcined in the same manner and used for carrying a catalytic component. A particularly high performance and strength can be obtained with good result when a composition produced by calcining a molybdenum (Mo), vanadium (V) or tungsten (W) compound born on titanium oxide at 400.degree. to 700.degree. C. is used.

NOx removal catalyst containing an inorganic fiber

A process for producing a denitration catalyst comprising the following steps of immersing a base material composed of an inorganic fiber cloth in an aqueous slurry containing 5 to 20% by weight of at least one sol-form substance selected from the group consisting of silica sol, titania sol and zirconia sol, as a first component, 20 to 70% by weight of at least one inorganic oxide fine powder selected from the group consisting of those of titania, zirconia and cordierite, as a second component, and 1 to 3% by weight of at least one organic binder selected from the group consisting of polyvinyl alcohol, polyvinyl acetate and carboxymethyl cellulose, as a third component, removing superfluous liquid from the resulting base material, drying the base material, coating catalyst components onto the surface of the dried base material, and drying and calcining the resulting material, are proposed.

Process for producing a denitration catalyst

A catalyst for reducing nitrogen oxides in the exhaust gas with ammonia, having a catalyst composition coated on an inorganic fiber cloth as a substrate is provided. The inorganic fiber cloth is impregnated with at least one inorganic oxide selected from silica and said catalyst composition, preferably with an organic binder like polyvinyl alcohol, so that the weight ratio of the inorganic oxide/said inorganic fiber cloth is in the range of 0.05 to 0.8 and the inorganic oxide is substantially placed between the fibers constituting said inorganic fiber cloth. The above inorganic fiber cloth is preferably a glass fiber cloth, more preferably a glass fiber cloth which surface is acid-treated to have a layer deficient in alumina and calcium oxide.

Catalyst for reducing nitrogen oxides and process for making the catalyst

A coal combustion apparatus having prevented deterioration of a denitration catalyst due to volatile metal compounds contained in exhaust gases is provided, which apparatus comprises a combustion furnace, a denitration means for removing nitrogen oxides in an exhaust gas from the furnace by reducing nitrogen oxide with ammonia, a means for collecting ashes in the gas having left the denitration means and a means for recycling the collected ashes into the furnace, and is characterized in providing an oxygen concentration meter in the flow path of the gas between the furnace and the denitration means and also providing an oxygen concentration-controlling means relative to air fed inside the flow path of the gas from the furnace to the denitration means so as to control the oxygen concentration detected by the oxygen concentration meter to a definite value or higher.

Coal combustion apparatus provided with a denitration

A catalyst for denitration by catalytic reduction using ammonia capable of preventing catalyst deterioation due to vapors of heavy metal compounds contained in exhaust gases and having a high strength and a superior resistance to poisons and a process for producing the catalyst are provided, which catalyst comprises TiO.sub.2, oxide(s) of at least one of V, Cu, Fe and Mn and oxide(s) of at least one of Mo, W and Sn, the total of the mol number(s) of the oxide(s) of at least one of Mo, W and Sn falling within a range of 2.times.10.sup.-6 to 20.times.10.sup.-6 mol/m.sup.2 per the unit specific surface of the catalyst, and which process comprises having oxide(s) of at least one of Mo, W and Sn adsorbed and supported onto a composition comprising TiO.sub.2 prepared in advance and oxide(s) of at least one of V, Fe, Cu and Mn so as to give the above-specified total of the mol number(s) of oxide(s) of at least one of Mo, W and Sn.

Process for producing a catalyst for denitration by catalytic reduction

A catalyst or a catalyst structure for removing nitrogen oxides contained in exhaust gases, having a small pressure loss and hard to cause ash deposition, and a process for producing the same are provided, which catalyst comprises a mixture of a catalyst composition of titanium oxide and at least one member of oxides of vanadium, molybdenum and tungsten, and inorganic fibers, the clearances of the inorganic fibers are filled with said catalyst composition; the ration by weight of said catalyst composition to said inorganic fibers is 3 or more; and the apparent density of said catalyst is 0.8 g/cm.sup.3 or more; and which process comprises providing a composition containing titanium oxide and at least one member of oxides of vanadium, molybdenum and tungsten, calcining said composition at 500.degree.-650.degree. C., crushing the calcined material so that powder of 20.mu. or less can occupy 90% by weight or more of the crushed material, adding water to the crushed material to form a slurry, impregnating an inorganic fiber sheet with the above slurry, placing the resulting sheet between porous molds, drying and molding it, and clacining the resulting molded material at 300.degree.-650.degree. C.

Catalyst for removing nitrogen oxides and a process for producing the

An exhaust gas-purifying catalyst capable of carrying out the CO-oxidizing reaction and the reduction reaction of NO.sub.x with NH.sub.3 in the same reactor and with good efficiency, and a process for purifying exhaust gases using the catalyst are provided, which catalyst comprises Cu and/or Co supported by Zr oxide or Ti oxide mixed with a Cu-substituted type zeolite.

Exhaust gas-purifying catalyst and process for purifying exhaust gases

A high performance catalyst for combustion is provided which includes a heat-resistant carrier capable of retaining a high specific surface area even when it is used at a high temperature of 1,000.degree. C. or higher for a long time, and processes for producing and using the same are provided, which catalyst comprises a compound expressed by a composition formula of BaAl.sub.12 O.sub.19, and the process for producing the catalyst comprises kneading .gamma.-alumina or aluminum hydroxide and a barium compound or impregnating the former compound with the latter so as to give an atomic ratio of Al/Ba in the range of 100/1 to 100/15, followed by calcination. The process of using the catalyst comprises contacting a volatile organic material under combustion conditions with a catalytic amount of BaAl.sub.12 O.sub.19 and producing combustion products.

Catalyst for combustion and process for producing same

A catalyst for denitration by catalytic reduction using ammonia capable of preventing catalyst deterioation due to vapors of heavy metal compounds contained in exhaust gases and having a high strength and a superior resistance to poisons and a process for producing the catalyst are provided, which catalyst comprises TiO.sub.2, oxide(s) of at least one of V, Cu, Fe and Mn and oxide(s) of at least one of Mo, W and Sn, the total of the mol number(s) of the oxide(s) of at least one of Mo, W and Sn falling within a range of 2.times.10.sup.-6 to 20.times.10.sup.-6 mol/m.sup.2 per the unit specific surface of the catalyst, and which process comprises having oxide(s) of at least one of Mo, W and Sn absorbed and supported onto a composition comprising TiO.sub.2 prepared in advance and oxide(s) of at least one of V, Fe, Cu and Mn so as to give the above-specified total of the mol number(s) of oxide(s) of at least one of Mo, W and Sn.

Catalyst for denitration by catalytic reduction using ammonia and a

A catalyst for removing nitrogen oxides contained in exhaust gases, particularly those containing vapor-form catalyst poisons, by catalytic reduction with ammonia, while retaining a high denitration performance for a long time, which catalyst comprises titanium oxide as a first component, molybdenum oxide and/or tungsten oxide as a second component and vanadium oxide and/or sulfate as a third component, the atomic ratio of the respective elements being Ti:Mo and/or W:V=80-96.6:3-15:0.5-5, and the size of the crystallite of the titanium oxide according to Sherrer's equation being in the range of 185 .ANG. to 300 .ANG. in the direction of a plane (101) (interplanar spacing: d=3.52 .ANG.).

Catalyst for removing nitrogen oxides

A catalyst for removing nitrogen oxides whose activity deterioration due to volatile poisons contained in exhaust gases is prevented and which has a superior endurance, and a process for producing the catalyst are provided, which catalyst comprises a titania having a surface area of 20 m.sup.2 /g or less and a zeolite having 0.01 to 20% by weight of copper supported thereon; having an average pore diameter of 10 .ANG. or less; and having a silica/alumina molar ratio of 10 or more, and which process comprises mixing powder of the zeolite with the titania or its precursor, followed by molding the mixture into a predetermined shape, followed by calcining the resulting material at 800.degree. C. or higher.

Catalyst for removing nitrogen oxide and process for producing the

A high performance catalyst for combustion having a cheap and heat-resistant carrier capable of retaining a high specific surface area even when it is used at a high temperature of 1,000.degree. C. or higher for a long time, and a process for producing the same are provided, which catalyst comprising a compound expressed by a composition formula of BaAl.sub.12 O.sub.19, and said process comprises kneading .gamma.-alumina or aluminum hydroxide and a barium compound or impregnating the former compound with the latter so as to give an atomic ratio of Al/Ba in the range of 100/1 to 100/15, followed by calcination.

An ammonia reduction-denitration process for exhaust gases containing NO.sub.x consisting mainly of NO.sub.2, and an apparatus therefor are provided, which process comprises treating the exhaust gases with ammonia using a catalyst which is active to both a reaction of (NO.sub.2 +NH.sub.3 .fwdarw.N.sub.2 +N.sub.2 O+H.sub.2 O) and a reaction of (N.sub.2 O+NH.sub.3 .fwdarw.N.sub.2 +H.sub.2 O) at an area velocity of 3 m/h or less and in a concentration ratio of NH.sub.3 /NO.sub.2 of 1.3 or more. According to this process, it is possible to reduce NO.sub.2 contained in the exhaust gases with ammonia at one stage without by-producing N.sub.2 O.

Ammonia reduction-denitration process and apparatus therefor

The present invention relates to a plate-shaped catalyst unit for NOx reduction of exhaust gas, wherein molten metal is sprayed upon surfaces of a metal plate allowing the molten metal to accumulate thereon to form rough surfaces, and the rough surfaces thus obtained are deposited with a catalytic substance for NOx reduction of exhaust gas. The catalyst units thus obtained are each disposed in parallel with the gas flow, and generally arranged across the gas flow and at intervals in the catalytic reactor which is placed in an exhaust gas duct and used as an apparatus for nitrogen oxides (NOx) reduction of exhaust gas.

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Kure, Japan

Kunihiko Konishi