A NO.sub.x adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NO.sub.x adsorber catalyst comprises a first layer consisting essentially of a support material, one or more platinum group metals disposed on the support material, and a NO.sub.x storage material.

A NO.sub.x adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NO.sub.x adsorber catalyst comprises a first layer consisting essentially of a support material, one or more platinum group metals disposed on the support material, and a NO.sub.x storage material.

Fluidizable catalysts for the gas phase oxygen-free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene. The catalysts comprise 5-20% by weight per total catalyst weight of one or more vanadium oxides (VO.sub.x), such as V.sub.2O.sub.5. The dehydrogenation catalysts are disposed on an alumina support that is modified with calcium oxide to influence characteristics of lattice oxygen at the catalyst surface. Various methods of preparing and characterizing the catalyst as well as methods for the gas phase oxygen free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene, with improved alkane conversion and olefin product selectivity are also disclosed.

Fluidizable catalysts for the gas phase oxygen-free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene. The catalysts comprise 5-20% by weight per total catalyst weight of one or more vanadium oxides (VO.sub.x), such as V.sub.2O.sub.5. The dehydrogenation catalysts are disposed on an alumina support that is modified with calcium oxide to influence characteristics of lattice oxygen at the catalyst surface. Various methods of preparing and characterizing the catalyst as well as methods for the gas phase oxygen free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene, with improved alkane conversion and olefin product selectivity are also disclosed.

A catalytic converter with excellent OSC performance and NO.sub.x purification performance. The converter includes a substrate with a cell structure through which exhaust gas flows, and a catalyst layer formed on a cell wall surface of the substrate. The catalyst layer includes a lower catalyst layer and an upper catalyst layer, the lower catalyst layer being formed on a surface of the substrate, and the upper catalyst layer being formed on a surface of the lower catalyst layer. The upper catalyst layer includes at least a zirconia support with rhodium carried thereon, and two types of ceria-zirconia-based composite oxides with different specific surface areas, each of the ceria-zirconia-based composite oxides having no rhodium carried thereon. The lower catalyst layer includes an alumina support with platinum carried thereon, and a ceria-zirconia-based composite oxide.

A catalytic converter with excellent OSC performance and NO.sub.x purification performance. The converter includes a substrate with a cell structure through which exhaust gas flows, and a catalyst layer formed on a cell wall surface of the substrate. The catalyst layer includes a lower catalyst layer and an upper catalyst layer, the lower catalyst layer being formed on a surface of the substrate, and the upper catalyst layer being formed on a surface of the lower catalyst layer. The upper catalyst layer includes at least a zirconia support with rhodium carried thereon, and two types of ceria-zirconia-based composite oxides with different specific surface areas, each of the ceria-zirconia-based composite oxides having no rhodium carried thereon. The lower catalyst layer includes an alumina support with platinum carried thereon, and a ceria-zirconia-based composite oxide.

The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H.sub.2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H.sub.2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

Increase propane dehydrogenation activity of a partially deactivated dehydrogenation catalyst by heating the partially deactivated catalyst to a temperature of at least 660° C., conditioning the heated catalyst in an oxygen-containing atmosphere and, optionally, stripping molecular oxygen from the conditioned catalyst.

Increase propane dehydrogenation activity of a partially deactivated dehydrogenation catalyst by heating the partially deactivated catalyst to a temperature of at least 660° C., conditioning the heated catalyst in an oxygen-containing atmosphere and, optionally, stripping molecular oxygen from the conditioned catalyst.