Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200.degree.-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: Fluorine compounds such as C2F6, CF4, CHF3, SF6 and NF3, are made in contact with a fluorine compound decomposition catalyst and a catalyst the decomposition oft least one of CO, SO2F2 and N2O in the presence of water or in the presence of water and oxygen. The catalyst the decomposition oft least one of CO, SO2F2 and N2O preferably contains at least one selected from Pd, Pt, Cu, Mn, Fe, Co, Rh, Ir and Au in the form of a metal or an oxide. According to the invention, the fluorine compound can be converted to HF, which is liable to be absorbed by water or an alkaline aqueous solution, and a substance, such as CO, SO2F2 and N2O, formed by decomposition of the fluorine compound can also be decomposed.

Abstract: An exhaust gas purification apparatus for use in an internal combustion engine comprises an exhaust gas duct connected to the engine through which exhaust gas containing NOx gas passes, and a catalyst disposed in the exhaust gas duct such that it contacts the exhaust gas. The catalyst chemically adsorbs NOx when a stoichiometric amount of a gaseous oxidizing agent present in the exhaust gas is larger than that of a gaseous reducing agent present in the exhaust gas for reducing NOx, adsorbed NOx is catalytically reduced in the presence of a reducing agent when the stoichiometric amount of the oxidizing agent is not larger that of the reducing agent.

Abstract: In a method and apparatus for removing nitrogen oxides from the exhaust gas of a lean-burn automobile, a CO adsorbent component, which may, for example be made of Pd, Ru or Ir, is contained in an exhaust gas cleaning catalyst which captures NOx when the air-fuel ratio of exhaust gas is higher than theoretical air-fuel ratio, and reduces the captured NOx when the air-fuel ratio of exhaust gad is less than or equal to the theoretical air-fuel ratio. The catalyst, which includes Rh, Pt, and element selected from among the alkaline and alkaline earth metals (Na, Mg, K, Li, Cs, Sr and Ca), and a CO adsorbent material comprising Pd, Ir or Ru, has a CO desorption capacity that reaches at maximum level at a temperature within the range from 200 to 220° C. when its temperature is increased in a He gas flow at the rate of 5 to 10° C./min, after said catalyst is saturated at 100° C.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: Nitrogen oxides contained in an exhaust gas emitted from a lean-burn engine-mounted internal combustion engines are eliminated with a high efficiency. In an exhaust gas purification apparatus and process for eliminating nitrogen oxides contained in a combustion exhaust gas emitted from an internal combustion engine with a reducing gas such as carbon monoxide, hydrocarbons, etc. contained in the exhaust gas in the presence of a catalyst, a catalyst comprising all of Rh, Pt and Pd, at least one member selected from alkali metals and alkaline earth metals, and Mn or its compound, supported on a porous carrier is used.

Abstract: A catalyst for use in purifying exhaust gas from an internal combustion engine. The active components of an exhaust gas purification catalyst for an internal combustion engine tend to be melted or softened and then to move outside the carrier, because the components become in contact with exhaust gas at a high temperature. Hence, anchoring materials are provided between carriers in order to suppress the moving of catalytically active components. Anchoring materials 22 do not form compounds with catalytically active components 24, and are selected from substances that do not melt even in contact with exhaust gas at a high temperature. When the active components contain sodium, potassium, cesium, lithium, strontium, barium, noble metals and the like, the best anchoring material is MgO. The anchoring material functions as a barrier that prevents the moving of active components.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: A gas stream containing at least one fluorine compound selected from the group consisting of compounds of carbon and fluorine, compounds of carbon, hydrogen and fluorine, compounds of sulfur and fluorine, compounds of nitrogen and fluorine and compounds of carbon, hydrogen, oxygen and fluorine is contacted with a catalyst comprising at least one of alumina, titania, zirconia and silica, preferably a catalyst comprising alumina and at least one of nickel oxide, zinc oxide and titania in the presence of steam, thereby hydrolyzing the fluorine compound at a relatively low temperature, e.g. 200°-800° C., to convert the fluorine of the fluorine compound to hydrogen fluoride.

Abstract: An object of the present invention is to improve the decomposition at low temperatures of perfluorocompounds containing only fluorine as a halogen, such as CF4, C2F6 and the like. In the present invention, a perfluorocompound containing only fluorine as a halogen is brought into contact with a catalyst comprising Al, Ni and W as catalytically active ingredients and comprising a mixed oxide or complex oxide of Ni and Al and a mixed oxide or complex oxide of W and Ni, in the presence of steam or a combination of steam and air at a temperature of 500 to 800° C. to convert the fluorine in the perfluorocompound to hydrogen fluoride. Employment of the catalyst of the present invention improves the decomposition at low temperatures and hence makes it possible to decompose the perfluoro-compound at a high percentage of decomposition at a lower temperature.

Abstract: Nitrogen oxides contained in an exhaust gas emitted from a lean-burn engine-mounted internal combustion engines are eliminated with a high efficiency.

Abstract: In an exhaust gas purification process for eliminating nitrogen oxides contained in a combustion exhaust gas emitted from an internal combustion engine with a reducing gas such as carbon monoxide, hydrocarbons, etc. contained in the exhaust gas in the presence of a catalyst, a catalyst comprising all of Rh, Pt and Pd, at least one member selected from alkali metals and alkaline earth metals, and Mn or its compound, supported on a porous carrier is used.

Abstract: A catalyst being formed of a porous supporter supporting alkali metals, Ti and noble metal, or further supporting at least one of rare earth metal and magnesium, being disposed in a flow passage of the internal combustion engine, and being used to purify NOx contained in the exaust gas. The above catalyst has excellent NOx resistance not only to the exaust gas burnt with the stoichiometric air-to-fuel ratio or rich condition, but to the exhaust gas burnt with the lean condition, and furthermore has a high resistivity to poisoning of SOx slightly contained in the fuel.

Abstract: An exhaust gas purification apparatus for use in an internal combustion engine comprises an exhaust gas duct connected to the engine through which the exhaust gas containing NOx gas passes and a catalyst so disposed in the exhaust gas duct that it contacts with the exhaust gas. The catalyst chemically adsorbs NOx under the condition that a stoichiometric amount of a gaseous oxidizing agent present in the exhaust gas is larger than that of a gaseous reducing agent present in the exhaust gas for reducing NOx, while NOx being adsorbed is catalytically reduced in the presence of the reducing agent under the condition that the stoichiometric amount of the oxidizing agent is not larger than that of the reducing agent. Thereby, NOx, the lean burn exhaust gas in the engine can be effectively made harmlessly.

Abstract: In order to prevent exhaust pipe for exhausting perfluorocompound (PFC) decomposition gas after washing from corrosion, a mist separating apparatus is provided at a rear stage of the washing tower for washing the PFC decomposition gas. The corrosion of the exhaust pipe can be prevented by removing the mist from the washed gas.

Abstract: An exhaust gas purification apparatus for use in an internal combustion engine comprises an exhaust gas duct connected to the engine through which the exhaust gas containing NOx gas passes and a catalyst so disposed in the exhaust gas duct that it contacts with the exhaust gas. The catalyst chemically adsorbs NOx under the condition that a stoichiometric amount of a gaseous oxidizing agent present in the exhaust gas is larger than that of a gaseous reducing agent present in the exhaust gas for reducing NOx, while NOx being adsorbed is catalytically reduced in the presence of the reducing agent under the condition that the stoichiometric amount of the oxidizing agent is not larger that of the reducing agent. Thereby, NOx the lean burn exhaust gas in the engine can be effectively made harmlessly.