Patent ID: 8258071
Filing Date: 2012-09-04
Classification: B01J

Abstract:
1. A zeolite catalyst consisting essentially of grains, each grain being formed by a zeolite core covered by at least one external zeolite layer having a different crystallographic structure than that of the core, the core consisting essentially of an acidic crystallized microporous solid zeolite and having a size of between about 0.5 micron and about 20 microns, wherein the external layer is a crystallized microporous solid zeolite and has a uniform thickness with a uniformity criterion, C, which is less than 0.30, whereby said uniformity criterion C is defined as being equal to an average, on a number N of catalyst grain samples, of the ratio of the difference between the maximum thickness, Ei max , of the external layer and the minimum thickness, Ei min , of this same layer to the average of these two thicknesses Ei max , and Ei min , and with the provision that the grains have a spherical shape and have an overall average thickness of the external layer of between 0.1 and 10 microns yielding a maximum average grain size of about 40 microns.