CATALYST IN THE FORM OF GRAINS COMPRISING AN ACIDIC POROUS CORE SURROUNDED BY A UNIFORM OUTER LAYER

摘要

The invention relates to a catalyst in the form of grains, wherein each grain consists of a core which is covered by at least one outer layer. The core is made of an acidic porous solid and has a size ranging from 0.1 microns to 0.4 millimetres. The outer covering thereof has a uniform thickness with a uniformity criterion C which is less than 0.30, wherein said uniformity criterion C is defined as being equal to an average, for a number N of samples of grains of catalyst, of the ratio of the difference between the maximum thickness, Eimax, of the outer layer and the minimum thickness, Eimin, of said layer with regard to the average for said two thicknesses Eimax and Eimin.