A lean NO.sub.x trap catalyst and its use in an emission treatment system for internal combustion engines is disclosed. The lean NO.sub.x trap catalyst comprises a first layer for storing nitrogen oxides (NOx) under lean exhaust gas conditions and releasing and/or reducing stored NOx during rich exhaust gas conditions, and a second layer, said second layer comprising a first zone for oxidizing carbon monoxide (CO) and/or hydrocarbons (HC), and a second zone for oxidizing nitric oxide (NO), and a substrate having an inlet end and an outlet end.

High activity metal nanoparticle catalysts, such as Pd or Pt nanoparticle catalyst, are provided. Adsorption of metal precursors such as Pd or Pt precursors onto carbonbased materials such as graphene followed by solventless (or low-solvent) microwave irradiation at ambient conditions results in the formation of the catalysts in which metal nanoparticles are supported on i) the surface of the carbon based materials and ii) in/on/within defects/holes in the carbon based materials.

Disclosed is a catalyst of a fiber form having improved the lifespan performance while being applied to the oxidation-reduction reaction of a high temperature and a manufacturing method thereof. Particularly, disclosed is a composite nanofiber catalyst including a support having a fiber form and a metal catalyst included in the support and a manufacturing method thereof.

A process for preparing a catalyst includes impregnating a metal oxide carrier with an aqueous solution to form an impregnated carrier; drying the impregnated carrier to form a dried, impregnated carrier; and heat-treating the dried, impregnated carrier in air to form the catalyst; wherein: the aqueous solution includes a copper salt; and from about 3 wt % to about 15 wt % of a C.sub.3-C.sub.6 multifunctional carboxylic acid; and the catalyst includes from about 5 wt % to about 50 wt % copper oxide.

A process for the preparation of a catalyst comprising palladium, a porous support with a specific surface area in the range 140 to 250 m.sup.2/g, said catalyst being prepared by a process comprising the following steps: a) preparing a colloidal solution of palladium oxide or palladium hydroxide in an aqueous phase; b) adding said solution obtained from step a) to said porous support at a flow rate in the range 1 to 20 litre(s)/hour; said porous support being contained in a rotary impregnation device functioning at a rotational speed in the range 10 to 20 rpm; c) optionally, submitting the impregnated porous support obtained from step b) to a maturation; d) drying the catalyst precursor obtained from step b) or c); e) calcining the catalyst precursor obtained from step d).

The present disclosure provides a PdIn alloy catalyst including a carrier and Pd metal particles supported by the carrier, the carrier is a nitrogen-doped porous carbon composite material having a plurality of passages, Pd metal particles are distributed in the plurality of passages, the nitrogen-doped porous carbon composite material includes a nitrogen-doped porous carbon material, a plurality of indium oxide particles, and In metal particles. The In metal particles are exposed through the plurality of passages, the plurality of indium oxide particles are uniformly distributed in the nitrogen-doped porous carbon material, and In atoms of the In metal particles migrated to surfaces of Pd particles selectively occupy edge and corner positions of metal lattice of Pd metal particles. The present disclosure further provides a method for manufacturing the PdIn alloy catalyst and application thereof.

A catalyst comprises an active phase constituted by palladium, and a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina, in which: the palladium content in the catalyst is in the range 0.0025% to 1% by weight with respect to the total weight of catalyst; at least 80% by weight of the palladium is distributed in a crust at the periphery of the porous support, the thickness of said crust being in the range 25 to 500 m; the specific surface area of the porous support is in the range 1 to 50 m.sup.2/g; the metallic dispersion D of the palladium is less than 20%.

A catalyst comprises an active phase constituted by palladium, and a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina, in which: the palladium content in the catalyst is in the range 0.0025% to 1% by weight with respect to the total weight of catalyst; at least 80% by weight of the palladium is distributed in a crust at the periphery of the porous support, the thickness of said crust being in the range 25 to 450 m; the specific surface area of the porous support is in the range 70 to 160 m.sup.2/g; the metallic dispersion D of the palladium is less than 20%.

A method for preparing methyl methacrylate from methacrolein and methanol. The method comprises contacting a mixture comprising methacrolein, methanol and oxygen with a heterogeneous catalyst comprising a support and a noble metal, wherein said catalyst has an average diameter of at least 200 microns and at least 90 wt % of the noble metal is in the outer 70% of catalyst volume, and wherein oxygen concentration at a reactor outlet is from 0.5 to 7.5 mol %.

A method for preparing methyl methacrylate from methacrolein and methanol. The method comprises contacting a mixture comprising methacrolein, methanol and oxygen with a heterogeneous catalyst comprising a support and a noble metal, wherein said catalyst has an average diameter of at least 200 microns and at least 90 wt % of the noble metal is in the outer 50% of catalyst volume.