Abstract: A catalyst for purifying exhaust gases includes a porous support; a cerium oxide or a solid solution of a cerium oxide and a zirconium oxide in a state of mutual solid solution, loaded on the porous support; and a noble metal element loaded on the porous support. The cerium oxide or the solid solution has an average particle diameter of from 5 to 100 nm. The cerium oxide is present in the solid solution in an amount of from 0.2 to 4.0 by molar ratio with respect to the zirconium oxide therein. The catalyst can be prepared by: coating and calcinating on a support substrate a slurry of a cerium oxide sol, a cerium oxide sol and a zirconium oxide sol, on a solid solution powder of a cerium oxide and a zirconium oxide in a state of mutual solid solution; and loading a noble metal element thereon.

Abstract: A catalyst for purifying carbon monoxide, hydrocarbons and nitrogen oxides in exhaust gases at the stoichiometric point or in oxygen-rich atmospheres, is disclosed, and it includes a support in which at least one element selected from the group consisting of alkali metals, alkaline-earth metals and rare-earth elements including La is dissolved in titania to form a solid solution, and a noble metal catalyst ingredient loaded on the support. A process for purifying, by bringing the exhaust gases into contact with the catalyst, is also disclosed.

Abstract: An automotive exhaust catalyst includes a support, which is less likely to adsorb SO.sub.x contained in exhaust gases thereon, an NO.sub.x storage compound loaded on the support, and a noble metal element loaded on the support. The support is an alumina support with a Ti--Zr composite oxide loaded thereon, or is formed of a Ti--Zr or Ti--Zr--Y composite oxide. The composite oxide inhibits the NO.sub.x storage compound, which is selected from alkali metals, alkaline-earth metals and rare-earth elements, from being poisoned by sulfur, and enhances the thermal resistance of the support. Thus, the automotive exhaust catalyst can effectively purify NO.sub.x contained in lean-side exhaust gases, even after it is subjected to a thermal durability test.

Abstract: A catalyst used for purifying exhaust gases resulting from the combustion of a lean fuel-air mixture mixture comprises a porous support material having a framework formed by MO.sub.2, where M is silicon or a metal, AlO.sub.2 and PO.sub.2, and at least one base metal and at least one metal of the platinum group which are carried on ion exchange sites of the support material a coexistent state. The catalyst exhibits a high level of NO.sub.x conversion for a long time even at a high temperature owing to the high heat resistance and durability of the support material, and the cooperative action of the two kinds of metals, i.e. the promotion of the catalytic action of the base metal (e.g. copper) by the metal of the platinum group (e.g. palladium) serving as cocatalyst.

Abstract: A catalyst for purification of exhaust gases, comprising a support substrate, a catalyst carrier layer formed on the support substrate and catalyst ingredients loaded on the catalyst carrier layer, wherein the catalyst carrier layer comprises alumina, cerium oxide, zirconium oxide and at least one oxide of rare earth element except cerium and lanthanum, and at least a part of cerium oxide, zirconium oxide and oxide of rare earth element except cerium and lanthanum is present in the form of composite oxide and/or solid solution. The catalyst for purification of exhaust gases is capable of purifying exhaust gases containing carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx).

Abstract: A catalyst for the purification of exhaust gases comprising a catalyst carrier layer and catalyst ingredients carried thereon, is capable of enhancing the purification property by suppressing the growth of cerium oxide particles and preventing the formation of LaAlO.sub.3. This catalyst has two composition types. One is a binary composition catalyst comprising oxides of cerium and zirconium in the catalyst carrier layer and the other is a ternary composition catalyst comprising oxides of cerium, zirconium and lanthanum in the catalyst carrier layer.

Abstract: A catalyst for purifying exhaust gases comprises: a perovskite-type complex oxide represented by the general formula Ln.sub.1-x A.sub.x MO.sub.3, wherein Ln represents at least one rare earth metal, A presents at least one alkaline earth metal and M represents at least one transition metal, and 0<x<1; at least one heat resistant complex oxide; and at least one precious metal. The heat resistant complex oxide is one of ABO.sub.3, LnAlO.sub.3 or Ln.sub.2 B.sub.2 O.sub.7, wherein A represents at least one alkaline earth metal, B represents at least one of Ti, Zr and Hf, and Ln represents at least one rare earth metal, and the precious metal is at least one of Pt, Pd, Rh, Ir, Ru and Os. The catalyst is usable as a temperature of 900.degree. C. or above without sintering or reduction of a catalytic activity.

Abstract: An exhaust gas purifying catalyst for oxidizing HC and CO and for reducing NOx is provided, which comprises at least one oxide of rare earth element, rhodium, and at least one of platinum and palladium loaded on alumina grains. The major amount of rhodium is dispersed on the oxide of rare earth element. Thus, the rhodium solidification into the alumina grains is prevented. Further, when cerium oxide accompanying lanthanum oxide, neodymium oxide or a mixture thereof is used as the oxide of rare earth element, the sintering of cerium oxide or palladium at a high temperature is suppressed since it forms a complex oxide with lanthanum oxide, neodymium oxide or a mixture thereof. Additionally, when stabilized alumina grains in which a rare earth element and an alkali earth element are present in a solid solution state are used, the deterioration of NOx purifying activity of the catalyst at a high temperature is suppressed.

Abstract: An alumina catalyst support stable at high temperatures comprises transformative alumina having a purity not less than 99.95% impregnated with lanthanum in an amount of 1.5 to 6 wt % based on the weight of the alumina. The alumina catalyst support has a surface area of at least 60 m.sup.2 /g after heating at 1200.degree. C. for 5 hours.

Abstract: An oxygen sensor for sensing the oxygen content of an exhaust gas from an automotive engine and a process for producing the same, which sensor is less sensitive to lead poisoning than conventional sensors. In the inventive sensor, a first platinum electrode is formed on the side of a solid electrolyte body exposed to the gas to be detected, and a second electrode is formed on the other side of the electrolyte body. The first electrode comprises a platinum layer and a layer of at least one of rhodium and palladium. Preferably, the layer of rhodium or palladium has a thickness of 10 to 5,000 .ANG..