Provided are: a hydrocarbon adsorbent capable of adsorbing hydrocarbons, storing the adsorbed hydrocarbons up to a relatively high temperature, and desorbing the adsorbed and stored hydrocarbons at a relatively high temperature; an exhaust gas purifying catalyst composition using the same; an exhaust gas purifying catalyst; and a method for treating an exhaust gas. The hydrocarbon adsorbent comprises a zeolite having an MRT-type framework structure. The hydrocarbon adsorbent comprises a small-pore zeolite having a total desorption amount ZD.sub.1 of propylene desorbed at 50° C. or higher and lower than 300° C. being 3.5 mmol/g or less and a total desorption amount ZD.sub.2 of propylene desorbed at 300° C. or higher and 500° C. or lower being 0.5 mmol/g or more, per 1 g by mass of the small-pore zeolite, when adsorbing propylene at 50° C. and then heating from 50° C. to 500° C. under the condition of 10° C./min by a temperature-programmed desorption method.

The present invention relates to a catalyst comprising two layers on an inert catalyst carrier, a layer A containing at least palladium as a platinum group metal, in addition to a cerium/zirconium/lanthanum/yttrium mixed oxide, and a layer B, which is applied to layer A, containing at least rhodium as the platinum group metal, in addition to a cerium/zirconium/lanthanum/yttrium mixed oxide.

Disclosed are a composite oxide which is capable of maintaining a large volume of pores even used in a high temperature environment, and which has excellent heat resistance and catalytic activity, as well as a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide. The composite oxide contains cerium and at least one element selected from aluminum, silicon, or rare earth metals other than cerium and including yttrium, at a mass ratio of 85:15 to 99:1 in terms oxides, and has a property of exhibiting a not less than 0.30 cm.sup.3/g, preferably not less than 0.40 cm.sup.3/g volume of pores with a diameter of not larger than 200 nm, after calcination at 900° C. for 5 hours, and is suitable for a co-catalyst in a catalyst for vehicle exhaust gas purification.

A exhaust gas purification apparatus is provided with: a substrate having a wall-flow structure and including entry-side cells, exit-side cells, and a porous partition; a first catalyst region formed in small diameter pores having relatively small pore diameters among internal pores in the partition; and a second catalyst region formed in large diameter pores having relatively large pore diameters among the internal pores in the partition. The first catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support, while the second catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support and other than at least the precious metal present in the first catalyst region.

The present invention relates to new crystalline zeolite SSZ-52x prepared using a quaternary ammonium cation templating agent, for example, having the structure:

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wherein X.sup.− is an anion which is not detrimental to the formation of the SSZ-52x. SSZ-52x is useful as a catalyst and shows improved durability, particularly with regard to NO.sub.x conversion.

A process for the removal of hydrogen sulfide and sulfur recovery from a H.sub.2S-containing gas stream by catalytic direct oxidation and Claus reaction through two or more serially connected catalytic reactors, wherein a specific control of the oxygen supplement is operated. The control and improvement of the process is obtained by complementing, in each major step of the process, the H.sub.2S-containing gas stream by a suitable flow of oxygen, namely before the H.sub.2S-containing gas stream enters the Claus furnace, in the first reactor of the process and in the last reactor of the process. Especially in application in a SubDewPoint sulfur recovery process the H.sub.2S/SO.sub.2 ratio is kept constant also during switch-over of the reactors R1 and R by adding the last auxiliary oxygen containing gas directly upstream the last reactor R so that the H.sub.2S/SO.sub.2 ratio can follow the signal of the ADA within a few seconds.

An exhaust gas treatment device includes a housing having a wall. The wall of the housing defines an interior chamber. A substrate is supported by the housing within the interior chamber of the housing. The substrate extends along a longitudinal axis. The substrate includes a flow through structure that allows the flow of exhaust gas to flow through the substrate. The substrate includes a catalytic composition disposed thereon for reacting with the flow of exhaust gas. The substrate includes a cavity, extending along a cavity axis, which is transverse to the longitudinal axis of the substrate. A sensor is attached to the housing. The sensor includes a probe that at least partially extends into the cavity of the substrate, for sensing a gaseous component in the flow of exhaust gas. The cavity mixes the flow of exhaust gas and directs the exhaust gas toward the probe of the sensor.

A device 2 to remove polar molecules like water vapor from an air stream is provided herein. The device includes a non-conductive housing 4 encapsulating a chamber 5 where the chamber 5 includes a fan 6 located at one end of the chamber 5 which allows air 24 to enter into the chamber 5, at least one metallic brush 12 is located inside a chamber and mounted on a dielectric holder 14, a curved solid wall 39 integrated with the non-conductive housing 4 at one end where the curved solid wall 39 allows smooth passage of air flow 24 from the chamber 5 and ensures minimum impingement on the brush 12, a curved wire mesh 40 integrated with the non-conductive housing 4 at the other end opposite to the curved solid wall 39, a power supply 18 to charge the metallic brush 12 and the curved wire mesh 40, where the metallic brush 12 when charged ionizes the air 24 to produce the ion current 26, facilitating removal of polar molecules from the air 24 to generate purified air 42 from the device 2.

A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Jr and Pt.

The invention provides for a method to prepare an alumina catalyst support comprising bismuth for emission control applications, to an alumina catalyst support prepared according to the method of the invention and to an alumina catalyst support comprising bismuth and having a specific crystallinity value that leads to improved technical effects.