The present invention provides a catalyst composition comprising a) platinum; b) rhodium; and c) a ceria-alumina composite, a zirconia composite or a mixture thereof, wherein platinum is supported on the ceria-alumina composite, zirconia composite or mixture thereof, wherein rhodium is supported on the ceria-alumina composite, zirconia composite or mixture thereof, wherein CeO.sub.2 in the ceria alumina composite is 1.0 to 50 wt. %, based on the total weight of the ceria-alumina composite, wherein the amount of ZrO.sub.2 in the zirconia composite is 50 to 99 wt. %, based on the total weight of the zirconia composite. The present invention also provides a catalytic article comprising the catalyst composition and its preparation.

The present disclosure provides a cerium-zirconium-based composite oxide with a core-shell structure and a preparation method thereof, a catalyst system using the cerium-zirconium-based composite oxide, a catalytic converter for purifying tail gas by using the catalyst system, and application of the catalyst system or the catalytic converter in motor vehicle exhaust purification, industrial waste gas treatment or catalytic combustion. In the present invention, the cerium-zirconium-based composite oxide with a core-shell structure oxygen storage material is prepared by a step-by-step precipitation method. On the one hand, yttrium and a part of zirconium and cerium are precipitated on a cerium-zirconium surface, where the post-precipitation of yttrium is to segregate yttrium ions (Y.sup.3+) on a grain boundary surface, thus reducing lattice surface energy, pinning the grain boundary surface, making the migration of the grain boundary surface difficult, controlling the growth of grains.

The present disclosure relates to a cerium-zirconium-based composite oxide having gradient element distribution and a preparation method therefor. According to the present disclosure, the cerium-zirconium-based composite oxide having gradient element distribution is prepared by a step-by-step precipitation method. First, a zirconium-rich component is precipitated to form a crystal structure and a crystal grain stack structure which have high thermal stability, slow down the segregation of zirconium on a surface after high-temperature treatment, and reduce element migration among crystal grains; second, a cerium-rich component is precipitated to improve the cerium content of the surface layers of the crystal grains, improve the utilization rate of the cerium element, and improve the oxygen storage amount and the oxygen storage rate.

The present disclosure relates to oxidation catalyst compositions comprising a platinum group metal (PGM) component comprising palladium, platinum, or a combination thereof; a first oxide chosen from oxides of cerium, silicon, iron, cobalt, zinc, chromium, molybdenum, nickel, tungsten, magnesium, antimony, tin, lead, yttrium, and combinations thereof; and a first refractory metal oxide support material; catalytic articles; and exhaust gas treatment systems, as well as methods of making and using such oxidation catalyst compositions.

An efficient photocatalyst nanocomposite comprising reduced graphene oxide, noble metal, and a metal oxide prepared by a one-step method that utilizes date seed extract as a reducing and nanoparticle determining size agent. The photocatalyst of the invention is a more effective sunlight photocatalyst than that prepared by traditional method in the photo decomposition of organic compounds in contaminated water.

The present disclosure provides a preparation method of an efficient and stable catalytic membrane based on a multi-scale hollow molecular sieve fiber, and belongs to the technical field of molecular sieve preparation. The preparation method includes the following steps: mixing a silicon source, an aluminum source, water, and an organic template, and stirring; heating, and adding deionized water; conducting a reaction by hydrothermal synthesis; conducting centrifugation on an obtained suspension, loading by mixing an obtained powder free of a mother liquor with an iron source, and washing and drying; dissolving a treated powder in anhydrous ethanol and conducting an ultrasonic treatment; adding a surfactant to an obtained dispersion, stirring, and conducting the ultrasonic treatment; and conducting coaxial electrospinning and calcination in sequence to obtain the membrane based on a hollow molecular sieve fiber.

An exhaust gas treatment system includes in order: an intake for receiving an exhaust gas from a lean burn combustion engine; an injector for the provision of a nitrogenous reductant; a close-coupled vanadium-containing SCR catalyst composition; one or more downstream PGM-containing oxidation catalyst compositions, wherein the close-coupled vanadium-containing SCR catalyst composition includes cerium in a Ce:V molar ratio of greater than 0.3.

A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component supported on a first PGM support material, wherein the first PGM component comprises rhodium (Rh) and platinum (Pt); and wherein Pt and Rh has a weight ratio of at least 1:10.

The present invention relates to a catalyst comprising a carrier substrate of the length L extending between substrate ends a and b and two washcoat zones A and B, wherein washcoat zone A comprises a first platinum group metal and extends starting from substrate end a over a part of the length L, and washcoat zone B comprises the same components as washcoat zone A and in addition a second platinum group metal and extends from substrate end b over a part of the length L, wherein L=L.sub.A+L.sub.B, wherein L.sub.A is the length of washcoat zone A and L.sub.B is the length of substrate length B.

A process for preparing a catalyst for selective hydrogenation of acetylene to ethylene, comprises: mixing palladium, gallium, and gold sources, silica, and a solvent to form a suspension, which is then subjected to filtration and drying so as to obtain a catalyst precursor; subjecting the catalyst precursor obtained to a calcination treatment; and subjecting a calcinated product obtained to a reduction reaction in a reducing atmosphere so as to obtain the catalyst. The catalyst prepared according to this process exhibits a high stability and high catalytic performance, and has a large number of active sites uniformly distributed.