Abstract: A catalyst for purifying exhaust gases includes a support including at le one composite selected from the group consisting of TiO.sub.2 --Al.sub.2 O.sub.3, ZrO.sub.2 --Al.sub.2 O.sub.3 and SiO.sub.2 --Al.sub.2 O.sub.3 composites, an NO.sub.x adsorbent including at least one member selected from the group consisting of alkali metals, alkaline-earth metals and rare-earth elements and loaded on the support, and a noble metal catalyst ingredient loaded on the support. The composites constituting the support improve initial NO.sub.x conversion of the catalyst, but also inhibit NO.sub.x purifying performance thereof from degrading even after a durability test.

Abstract: A method for purifying an exhaust gas by simultaneously removing carbon monoxide, hydrocarbons, and nitrogen oxides contained in the exhaust gas, comprising bringing the oxygen rich exhaust gas into contact with an exhaust gas purifying catalyst comprised of at least one noble metal selected from the group consisting of platinum and palladium, at least one alkaline earth metal selected from the group consisting of barium, magnesium, calcium, and strontium, and at least one alkali metal selected from the group consisting of iron, nickel, and cobalt, supported on a carrier composed of a porous substance.

Abstract: A catalyst for purifying exhaust gases includes a heat resistant support, a porous layer coated on the heat resistant support, a noble metal catalyst ingredient loaded on the porous layer, and an NO.sub.x storage component including at least one member selected from the group consisting of alkaline-earth metals, rare-earth elements and alkali metals, and loaded on the porous layer. In the catalyst, the noble metal catalyst ingredient and the NO.sub.x storage component are disposed adjacent to each other, and are dispersed uniformly in the porous layer. In fuel-lean (i.e., oxygen-rich) atmospheres, NO present in exhaust gases is oxidized to NO.sub.2 by the noble metal catalyst ingredient, and at the same time the resulting NO.sub.2 is stored in the NO.sub.x storage component which is disposed adjacent to the nobel metal catalyst. In the stoichiometric or fuel-rich (i.e., oxygen-lean) atmospheres, the stored NO.sub.

Abstract: A catalyst for purifying an exhaust gas for simultaneously removing carbon monoxide, hydrocarbons and nitrogen oxides contained in the exhaust gas under an oxygen rich atmosphere, comprising a carrier composed of a porous material, and barium oxide, lanthanum oxide and platinum supported on the carrier, and a method for purifying an exhaust gas by bringing the exhaust gas under an oxygen rich atmosphere into contact with the above-mentioned catalyst.

Abstract: A catalyst for purifying exhaust gases includes a porous support, an NO.sub.x storage component including at least one member selected from the group consisting of alkaline-earth metals, rare-earth elements and alkali metals, and loaded on the porous support, a noble metal catalyst ingredient loaded on the porous support, and disposed adjacent to the NO.sub.x storage component, and ceria (CeO.sub.2) disposed away from the noble metal catalyst ingredient. By disposing the noble metal catalyst ingredient adjacent to the NO.sub.x storage component, the reduction reactions of NO.sub.x can be facilitated in fuel-rich (i.e., oxygen-lean) atmospheres without being interfered by the ceria. By disposing the ceria away from the noble metal catalyst ingredient, oxygen, which has been stored thereon in fuel-lean (i.e., oxygen-rich) atmospheres, can be released from the ceria at a controlled rate in a controlled amount in fuel-rich (i.e.

Abstract: A catalyst for purifying exhaust gases includes a porous support, at least one catalyst ingredient selected from Pt and Pd, and additional ingredients including (1) at least two rare-earth elements including La, (2) at least one rare-earth element including La and at least one transition element selected from Fe, Ni, Co and Mn, (3) at least two alkali metals, (4) at least one alkali metal and at least one rare-earth element including La, (5) at least one alkali metal and at least one transition element selected from Fe, Ni, Co and Mn, (6) at least two alkaline-earth metals, (7) at least one alkaline-earth metal and at least one rare-earth element including La, or (8) Ba, Li, La, Ce and Zr. A process for purifying an exhaust gas, by contacting the catalyst with an exhaust gas, is also provided.

Abstract: A metallic support catalyst includes a honeycomb body, an outer cylinder and a catalyst ingredient loading layer, and has a geometric surface area of 40 cm.sup.2 /g or more with respect to its unit weight. The honeycomb body is formed of a flat metallic foil and a corrugated metallic foil, which are laminated and formed as a roll so as to form a plurality of honeycomb-shaped cells in the honeycomb body. The outer cylinder holds the honeycomb body therein. The catalyst ingredient loading layer is coated on the honeycomb-shaped cells of the honeycomb body. The honeycomb body can be formed of a flat metallic foil and a corrugated metallic foil, which have a thickness of from 0.02 to 0.04 mm. The catalyst ingredient loading layer can have a weight of from 60 to 150 g/liter with respect to a unit volume of said honeycomb body.

Abstract: A catalyst for purifying carbon monoxide, hydrocarbons and nitrogen oxides in exhaust gases at the stoichiometric point or in oxygen-rich atmosphere, is disclosed, and it includes a porous support, at least one noble metal catalyst ingredient loaded on the porous support, and selected from the group consisting of platinum, palladium and rhodium, and at least one NO.sub.X adsorbent loaded on the porous support, selected from the group consisting of alkali metals, alkaline-earth metals and rare-earth elements, and having an average particle diameter falling in a range of from 0.1 to 20 micrometers. A process for purifying, by bringing the exhaust gases into contact with the catalyst, is also disclosed.

Abstract: A catalyst for purifying exhaust gases comprises a catalyst carrier made of potassium titanate and a noble metal loaded on the catalyst carrier. The catalyst carrier is substantially free from alumina. This catalyst can oxidize at least hydrocarbons in exhaust gases at a high catalytic activity even at low temperatures, and at the same time can suppress SO.sub.2 from converting into sulfates. This catalyst does not employ substance like alumina exhibiting solid acidity as a catalyst carrier. Further, this catalyst can be used for purifying exhaust gases from diesel engines to suppress particulates and sulfates from being emitted, and to improve conversions of hydrocarbons and carbon monoxide.

Abstract: A process for purifying an exhaust gas comprising carbon monoxide, hydrocarbons, nitrogen oxides, and sulfur oxides by periodically adjusting exhaust gas conditions from lean-burn to fuel-rich and by using a catalyst comprising an alumina support with lithium dissolved therein to form a solid solution, at least one first ingredient selected from the group consisting of platinum and palladium loaded on the alumina support, and at least one second ingredient selected from the group consisting of alkali elements, alkaline-earth elements, and rare-earth elements loaded on the support. Sulfates formed from sulfur oxides in the exhaust gas are decomposed by the lithium under the fuel-rich conditions to inhibit the alumina support from being acidified.

Abstract: A method for the catalytic purification of an oxygen-rich exhaust gas, wherein the catalyst comprises: a catalyst support, a zeolyte layer formed on the catalyst support and noble metals such as platinum, palladium and rhodium loaded on the catalyst. The catalyst for purifying the exhaust gas maintains a superior exhaust gas conversion performance over a long period of time.

Abstract: A catalyst for purification of exhaust gases comprising: a support substrate; an active alumina coating layer comprising at least one of nickel oxide and cobalt oxide formed on the surface of the support substrate; a composite oxide comprising cerium oxide and zirconium oxide formed in the active alumina coating layer; and noble metal catalyst ingredients comprising at least one of platinum, palladium and rhodium loaded on the active alumina coating layer. The catalyst offers a decreased hydrogen sulfide H.sub.2 S emission and conversion ratios for hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOx) equivalent to or superior to those of conventional catalysts.

Abstract: Exhaust gas purifying catalyst characterized in that a carrier carries as the catalytic elements, a Pt-family element or elements containing over 50 weight % of Pt and an alkaline metal in proportions of 0.001.about.1 mole per 1 kg of catalyst; or the carrier carries Ce additionally.