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 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

An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer facing the substrate and including a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope. Another exhaust gas-purifying catalyst includes a substrate, and a catalytic layer formed on the substrate using slurry containing a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope.

Exhaust gas purifying catalyst

An exhaust emission control device for an internal combustion engine, capable of supplying a just enough amount of reducing agent to a selective reduction catalyst even when a NOx purification ratio of the catalyst is changed by various causes, thereby enabling a high NOx purification ratio and very low exhaust emissions to be maintained. An ECU calculates a filtered value based on a signal from an exhaust gas concentration sensor, calculates a moving average value of a product of the filtered value and a reference input, calculates a control input such that the moving average value becomes equal to 0, and adds a reference input to the control input to calculate an FB injection amount. The ECU calculates an FF injection amount with a predetermined feedforward control algorithm, and adds the FF injection amount to the FB injection amount, to thereby calculate a urea injection amount.

Exhaust emission control device for internal combustion engine

There is disclosed a hydrothermally stable microporous crystalline material comprising a molecular sieve or zeolite having an 8-ring pore opening structure, such as SAPO-34 or aluminosilicate zeolite, able to retain a specific percentage of its surface area and micropore volume after treatment with heat and moisture, such as at least 80% of its surface area and micropore volume after exposure to temperatures of up to 900 0C in the presence of up to 10 volume percent water vapor for a time ranging from 1 to 16 hours. Methods of using the disclosed crystalline material, such as in the SCR of NOx in exhaust gas are also disclosed, as are methods of making such materials.

Novel microporous crystalline material comprising a molecular sieve or zeolite having an 8-ring pore opening structure and methods of making and using same

PURPOSE:To attain excellent peculiar effects such as a very slight change with the lapse of time as well as to enable efficient catalytic decomposition of N2O in exhaust gas by carrying iridium and at least one among Nb2O5, Tie2 and ZrO2 on a hydrophobic carrier. CONSTITUTION:This catalyst for decomposition of nitrous oxide is a catalyst obtd. by carrying iridium and one or more kinds of oxides selected among Nb2O5, TiO2, and ZrO2. on a hydrophobic carrier such as silica gel, activated alumina or silica-alumina. When this catalyst is produced, the hydrophobic carrier is immersed in an aq. soln. of iridium chloride for a certain time to impregnate the noble metal and the carrier is dried and further immersed in an aq. soln. of one or more among niobium chloride, titanium sulfate and zirconyl sulfate for a certain time to impregnate these precursors of oxides. The carrier is then dried, fired at 300-500 deg.C for 3-5hr and subjected to reduction treatment at 400-500 deg.C for 3-5hr in a flow of gaseous H2.

Catalyst for decomposition of nitrous oxide

PURPOSE:To obtain a catalyst for catalytic reduction of NOx capable of efficient reduction of NOx in exhaust gas without using a large amt. of a reducing agent and excellent in durability even in the presence of moisture by carrying cerium oxide on a solid acid carrier. CONSTITUTION:Cerium oxide is carried on a solid acid carrier to obtain the objective catalyst for catalytic reduction of NOx with hydrocarbon or an oxygen-contg. org. compd. as a reducing agent. The solid acid carrier is a carrier exhibiting solid acidity in a temp. region in which the catalyst is used. A zeolite type or oxide type solid acid carrier may be used as the solid acid carrier and the pref. amt. of the cerium oxide carried on the solid acid carrier is 5-80wt.% of the total amt. of them. The catalyst itself can be formed into one of various shapes such as a honeycomb or sphere shape by a known forming method.

Catalyst for catalytic reduction of nox

PURPOSE:To provide a catalyst for efficiently reducing nitrogen oxide in a waste gas in a wide temp. range even in the coexistence of oxygen and moisture by providing an inside layer having a catalytic component expressed by a specific formula and a surface layer carrying a specific catalytic component on the inside layer. CONSTITUTION:The inside layer constituting a catalytic structural body on the base material contains a perovskite type multiple oxide expressed by the formula (A expresses La, Y, Ce, Pr, Nd or the like, B expresses Na, K, Bi, Th, Ba, Sr, Ca or the like, C expresses Mn, Co, Fe, Ni, Cr, Cu, V, Mo, W, Ta, Li or the like and 0<=X<=1) as the catalytic component. And the surface layer on the inside layer has the catalytic component made by carrying at least one kind of metals, the ions or the oxides of Ib group, IIa group, IIb group, IIIa group, IIIb group, IVa group, IVb group, Va group, VIIa group and VIII group in the Periodical Table on at least one kind of carrier selected from aluminum oxide, titanium dioxide, zirconium oxide and H type zeolite.

Catalytic structure for nitrogen oxide catalytic reduction

PURPOSE:To remove NOx in an exhaust gas efficiently. CONSTITUTION:From a viewpoint that in the reduction reaction between NOx and hydrocarbons on a reduction catalyst in an oxidative atmosphere, NO2, is reduced more easily than NO, an exhaust gas is previously contacted with an oxidation catalyst to oxidize NO in the exhaust gas into NO2. The treated exhaust gas, in an oxidative atmosphere containing excessive oxygen and in the presence of hydrocarbons, is contacted with a reduction catalyst selected from zeolite of a proton type, zeolite of an alkali metal type, and acid metal oxide (metal oxide treated with a compound having sulfate group to reduce NO2, in the exhaust gas into nitrogen.

Treatment method for removing nitrogen oxide

PROBLEM TO BE SOLVED: To provide a method for catalytically decomposing NOx in exhaust gas formed by the combustion of fuel with high durability, by burning the fuel supplied by a periodical rich/lean fuel supply system even under the presence of oxygen, sulfur oxides or water and even at high reaction temperature, and to provide the catalyst for that purpose. SOLUTION: The catalyst is constituted by carrying metal and/or its oxide selected from rhodium, palladium, rhodium oxide, palladium oxide and a mixture of these on a zeolite.

忠夫仲辻

Papers

Catalyst for decomposition of nitrous oxide

Catalyst for catalytic reduction of nox

Catalytic structure for nitrogen oxide catalytic reduction

Treatment method for removing nitrogen oxide

Catalyst and method for catalycally recomposing nitrogen oxides

忠夫 仲辻

Papers

Catalyst for decomposition of nitrous oxide

Catalyst for catalytic reduction of nox

Catalytic structure for nitrogen oxide catalytic reduction

Treatment method for removing nitrogen oxide

Catalyst and method for catalycally recomposing nitrogen oxides

忠夫仲辻