A method of making a xylene isomerization catalyst comprises the steps of (i) contacting a ZSM-5 zeolite starting material having a silica to alumina molar ratio of 20 to 50 and having a mesopore surface area in the range of 50 m.sup.2/gram to 200 m.sup.2/gram in a reactor with a base to provide an intermediate zeolite material; (ii) recovering the intermediate ZSM-5 zeolite material of step (i); (iii) contacting the intermediate zeolite material with an acid to provide an acid treated ZSM-5 zeolite product; (iv) recovering the acid treated ZSM-5 zeolite material; and (v) calcining the acid treated ZSM-5 zeolite material to provide a desilicated ZSM-5 zeolite product having a silica to alumina molar ratio of 20 to 150 and having a mesopore surface area in the range of 100 m.sup.2/gram to 400 m.sup.2/gram.

A catalyst structure that allows prevention of aggregation of fine particles of a functional material, suppresses decrease of catalyst activity, and thus enables the extension of the lifetime of the catalyst structure. A catalyst structure is provided with: a support that is formed from a zeolite-type compound and has a porous structure; and at least one functional material present in the support. The functional material includes a first element that is at least one metallic element selected from the group consisting of cobalt, nickel, and iron. The support has paths connected to each other. The functional material including the first element is present in at least the paths of the support.

Methods are provided for forming noble metal catalysts comprising both platinum and a second Group VIII metal, such as palladium, with improved aromatic saturation activity. Instead of impregnating a catalyst with both platinum and another Group VIII metal at the same time, a sequential impregnation can be used, with the Group VIII metal being impregnated prior to platinum. It has been discovered that by forming a Group VIII metal-impregnated catalyst first, and then impregnating with platinum, the distribution of platinum throughout the catalyst can be improved. The improved distribution of platinum can result in a catalyst with enhanced aromatic saturation activity relative to a catalyst with a similar composition formed by simultaneous impregnation.

The present disclosure relates to a method for preparing a multi-level pore zeolite, including: (A) a step of mixing a silicon precursor, an aluminum precursor, a phosphorus precursor, a structure directing agent and water; a step of (B) adding phenylphosphonic acid, carbon black or a mixture thereof to the mixture prepared in the step (A) and mixing the same; a step of (C) crystallizing the mixture prepared in the step (B) by heat-treating the same; and a step of (D) calcining the crystallization product, and utilization of the prepared multi-level pore zeolite as a catalyst for hydroisomerization of normal paraffins. The catalyst exhibits improved isoparaffin yield when it is used as a catalyst for hydroisomerization of normal paraffins such as diesel or lube base oil by supporting an active metal component because residence time of reactants and products in the zeolite crystals are decreased due to mesopores and the proportion of external acid sites to total acid sites is low. Also, cloud point and pour point are effectively improved and high hydroisomerization reactivity is achieved without product loss.

A method of reducing nitrogen oxides in exhaust gas of an internal combustion engine by selective catalytic reduction (SCR) comprises contacting the exhaust gas also containing ammonia and oxygen with a catalytic converter comprising a catalyst (2) comprising at least one crystalline small-pore molecular sieve catalytically active component (Z.sub.M,I) having a maximum ring opening of eight tetrahedral basic building blocks, which crystalline small-pore molecular sieve catalytically active component (Z.sub.M,I) comprising mesopores.