Diesel particulate emission control

A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Ir and Pt.

Transition metal/zeolite scr catalysts

A catalyst for purifying exhaust gases exhibits not only effective purifying characteristics even in a low temperature range such as immediately after an engine starts but also high exhaust gas purifying ability. In the catalyst for purifying exhaust gases of a first aspect of the invention, HC adsorbed at low temperature are released at high temperature and the released HC are purified by a catalyst metal. This catalyst for purifying exhaust gases has an excellent advantage in purifying HC at low temperature as well as excellent exhaust gas purifying ability.

Catalyst for purifying exhaust gases

A novel catalyst for catalytic reduction of nitrogen oxide using a hydrocarbon as a reducing agent is provided, which comprises (a) at least an element of the platinum group selected from the group consisting of platinum, iridium, rhodium and ruthenium and (b) gold, and which may further comprises (c) at least a metallic oxide selected from the group consisting of cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide and gallium oxide.

Catalyst for catalytic reduction of nitrogen oxides

A system for NOx reduction in combustion gases, especially from diesel engines, incorporates an oxidation catalyst to convert at least a portion of NO to NO2, a particulate filter, a source of reductant such as NH3, and an SCR catalyst. Considerable improvements in NOx conversion are observed.

System for nox reduction in exhaust gases

A TiO 2 containing catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent is disclosed. There are also disclosed denitrizing catalysts which contain zeolite or perovskite structure complex compound.

Catalysts and methods for denitrization

There is provided a method of producing titanium oxides which comprises: admixing an aqueous solution of titanium tetrachloride with sulfuric acid in a molar ratio of sulfuric acid to titanium tetrachloride of at least 0.5 adding an alklai to the resultant solution to produce titanium hydroxide; and drying and calcining the titanium hydroxide. A further method is provided which comprises: adding a solution of an alkali to an aqueous solution of titanium tetrachloride having a concentration of not more than 2.5 moles/l at temperatures of not less than 50° C., thereby to substantially thermally hydrolyze the titanium tetrachloride and to produce titanium hydroxide; and drying and calcining the titanium hydroxide.

Method of producing titanium oxides

A catalyst for decomposing ozone comprising a carrier and a catalytic active substance having ozone resolvability carried thereon in a thickness of 10 to 200 μm. Consequently, ozone can efficiently be removed. The invention also includes the catalytic active substance or ozone adsorption substance which is contained in the carrier, such that the combination of the carrier and its contained material has ozone resolvability or ozone adsorbing ability in itself. Accordingly, the combination of these two features allows the thickness of the catalytic active substance carried on a carrier surface to be reduced to the range from 5 to 100 μm. Thus, improved productivity, durability of the catalyst and ozone removing efficiency are provided.

Catalyst for decomposing ozone

In a method for treating a gas containing dusts therein under a monolithic catalyst consisting of a ceramic support which is substantially porous throughout the structure, and has active ingredients uniformly dispersed therein and passages therethrough parallel to the flow of the gas for allowing the gas to pass therethrough, the improvement in which the catalyst has the sintered front portion or has a vitreous coating on the front portion. Alternatively, the improvement in which a metal or sintered ceramic lid having openings therethrough is fixed onto the front face of the catalyst with the passages in alignment with the openings of the lid.

Method for preventing the wear of a monolithic catalyst by dusts

Regeneration of an ozone decomposing reactor which comprises: a catalyst structure composed of a carrier having at least one passage extending therethrough for allowing an ozone containing fluid to pass through the catalyst structure and a catalyst and an electroconductive material carried in or on the carrier; and electrodes attached to the catalyst structure to electrify the structure, whereby to decompose ozone at elevated temperatures and regenerating deactivated structure by electrifying and heating. The carrier is either a ceramic honeycomb mold or a fiber board.

Tadao Nakatsuji

Papers

Catalysts and methods for denitrization

Method of producing titanium oxides

Catalyst for decomposing ozone

Method for preventing the wear of a monolithic catalyst by dusts

Ozone decomposing reactor regeneration