Abstract: Nitrogen oxides are removed from an exhaust gas containing nitrogen oxides and oxygen in a proportion larger than its stoichiometric proportion relative to unburned components in the exhaust gas, by (i) disposing an exhaust gas cleaner in a flow path, the exhaust gas cleaner comprising a first catalyst composed of 0.2-20 parts by weight (on a metal basis) of silver or silver oxide supported on a porous inorganic oxide, and a second catalyst composed of 1-50 parts by weight (on an oxide basis) of tungsten and/or vanadium supported on a porous inorganic oxide; (ii) introducing oxygen-containing organic compounds having 2 or more carbon atoms or a fuel containing the oxygen-containing organic compounds into the exhaust gas on the upstream side of the exhaust gas cleaner; and (iii) bringing the exhaust gas into contact with the exhaust gas cleaner at a temperature of 150-650° C., thereby causing a reaction of the nitrogen oxides with the oxygen-containing organic compounds to remove the nitrogen oxides.

Abstract: The present invention provides a process for synthesizing tertiary carboxylic acids or the esters thereof having one or two more carbon atoms than the raw material has, comprising reacting in a strong acid (e.g., sulfuric acid, sulfuric acid-phosphoric acid, hydrogen fluoride, fluorosulfuric acid, boron trifluoride.water complex and trifluoromethanesulfonic acid) a raw material compound (i.e., olefin, alcohol, diene, diol or saturated hydrocarbon) with carbon monoxide in the presence of a specific metal carbonyl catalyst (i.e., platinum carbonyl catalyst, palladium carbonyl catalyst and gold dicarbonyl catalyst).The metal carbonyl catalyst is formed by reacting in a strong acid at least one specific metal compounds (e.g., platinum compound such as platinum (II, IV) oxide, platinum (II, IV) hydroxide, a platinum powder, etc.; palladium compound such as palladium (II, III, IV) oxide, palladium (II) hydroxide, palladium (II) sulfate, palladium (II) carboxylate, a palladium powder, etc.

Abstract: An exhaust gas cleaner is constituted of an Ag catalyst carrying an Ag component and a base metal catalyst carrying a Cu component and optionally W, V, Mo components, and a noble metal catalyst carrying a noble metal component. The base metal catalyst and the noble metal catalyst may be physically mixed to form a mixed catalyst. Another exhaust gas cleaner is constituted of the first Ag catalyst carrying an Ag component, the second Ag catalyst carrying an Ag component, a base metal catalyst carrying a Cu component and optionally W, V, Mo components, and a noble metal catalyst carrying a noble metal component. The second Ag catalyst carries the Ag component in an amount larger than that of the first Ag catalyst. The noble metal catalyst is physically mixed with the base metal catalyst to form a mixed catalyst. The exhaust gas cleaner can effectively remove nitrogen oxides in a wide temperature range of exhaust gas.

Abstract: A three-dimensional network structure comprising three-dimensionally interconnected spherical silica particles, having specific physical characteristics including diameter, pores on the surfaces of the particles, cross-sectional areas of the bonds interconnecting the spherical silica particles, elasticity modulus, voids content, and silica content, the surfaces of the spherical silica particles being wholly or partly covered with a water-soluble polymer, the network structure being able to remain substantially intact when heat-treated and being able to undergo machining. There is also provided a method of making a three-dimensional network structure comprising spherical silica particles, comprising hydrolyzing and polymerizing a low polymer of an alkoxysilane in a mixed solution containing the alkoxysilane low polymer and a water-soluble polymer in a mixed solvent composed of water and an alcohol in the presence of an acid catalyst.