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

##STR00001##

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.

This exhaust gas purifying catalyst is provided with a substrate and a catalyst layer formed on a surface of the substrate. The catalyst layer contains zeolite particles that support a metal, and a rare earth element-containing compound that contains a rare earth element. The rare earth element-containing compound is added in such an amount that the molar ratio of the rare earth element relative to Si contained in the zeolite is 0.001 to 0.014 in terms of oxides.

The present invention relates to a catalyst for the oxidation of NO, for the oxidation of ammonia, for the oxidation of HC and for the selective catalytic reduction of NOx, comprising a flow through substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the flow through substrate extending therethrough; a first coating comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; a second coating comprising a first platinum group metal component supported on a non-zeolitic first oxidic material and further comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; optionally a third coating comprising a second platinum group metal component supported on a second oxidic material; wherein the third coating is disposed on the surface of the internal walls and under the second coating over z % of the axial length of the substrate from the outlet end to the inlet end, with z being in the range of from 0 to 100; wherein the second coating extends over y % of the axial length of the substrate from the inlet end to the outlet end and is disposed either on the surface of the internal walls, or on the surface of the internal walls and the third coating, or on the third coating, with y being in the range of from 95 to 100; wherein the first coating extends over x % of the axial length of the substrate from the inlet end to the outlet end and is disposed on the second coating, with x being in the range of from 20 to y.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

The present invention provides an exhaust gas purification catalyst including an alkaline earth metal supported in a highly dispersed state on a porous carrier. A catalyst layer of the exhaust gas purification catalyst provided by the invention has an alkaline earth metal-supporting region including a porous carrier, a catalyst metal belonging to the platinum group, and a sulfate of at least one type of alkali earth metal supported on the porous carrier. In a cross-section of this region, a Pearson correlation coefficient R.sub.Ae/M is at least 0.5 as calculated using α and β for each pixel obtained by carrying out area analysis by FE-EPMA under conditions of pixel size of 0.34 μm×0.34 μm, and measured pixel number 256×256, and by measuring the characteristic X-ray intensity (α:cps) of the alkaline earth metal element (Ae) and the characteristic X-ray intensity (β:cps) of the main constituent element of the inorganic compound constituting the porous carrier for each pixel.

Methods for exhaust gas purification, including the steps of: attaching an exhaust gas purification catalyst to an exhaust system of an internal combustion engine, and supplying an exhaust gas to the exhaust gas purification catalyst, where the exhaust gas purification catalyst includes an upper layer containing first carrier particles which are particles of an inorganic oxide and rhodium, and a lower layer containing second carrier particles which are particles of an inorganic oxide, the upper layer includes a rhodium-rich portion near the surface of the upper layer on the upstream side of the exhaust gas flow, and the existence range of the rhodium-rich portion is in a range of greater than 50% to 80% of the length of the upper layer from a downstream side end of an exhaust gas flow and of less than 20 μm in the depth direction from an outermost surface of the upper layer.

A passive NOx absorber for treating an exhaust gas from a diesel engine is described. The passive NOx absorber comprises a first washcoat region comprising a zeolite catalyst, the zeolite catalyst comprising a noble metal and a zeolite having a SAR of 2-15.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

In accordance with the technology herein disclosed, an exhaust gas purification catalyst exhibiting a high exhaust gas purifying performance using a new rare earth-containing material is provided. The exhaust gas purification catalyst herein disclosed includes a base material and a catalyst layer formed on the surface of the base material. The catalyst layer of such an exhaust gas purification catalyst includes rare earth-carrying alumina 50 including a primary particle of a rare earth particle 40 including at least one rare earth element carried on the surface of an alumina carrier 30 including alumina, and the average particle diameter D.sub.50 based on TEM observation of the rare earth particle 40 in the rare earth-carrying alumina 50 is 10 nm or less. As a result of this, it is possible to provide an exhaust gas purification catalyst having high NOx adsorption performance and CO adsorption performance

Methods for exhaust gas purification, including the steps of: attaching an exhaust gas purification catalyst to an exhaust system of an internal combustion engine, and supplying an exhaust gas to the exhaust gas purification catalyst, where the exhaust gas purification catalyst includes an upper layer containing first carrier particles which are particles of an inorganic oxide and rhodium, and a lower layer containing second carrier particles which are particles of an inorganic oxide, the upper layer includes a rhodium-rich portion near the surface of the upper layer on the upstream side of the exhaust gas flow, and the existence range of the rhodium-rich portion is in a range of greater than 50% to 80% of the length of the upper layer from a downstream side end of an exhaust gas flow and of less than 20 μm in the depth direction from an outermost surface of the upper layer.