Selective Crystallization of Aluminophosphate Molecular Sieve with AEL Structure

Abstract

The influence of temperature and ageing of initial aluminophosphate gels on their chemical and phase composition was studied. The hydrated oxide (boehmite) was used as the source of aluminum to prepare gels containing ammonium phosphate, undissolved pseudoboehmite and amorphous aluminophosphate in different proportions. The gel with predominant amorphous aluminophosphate was shown to provide selective crystallization of high phase purity AlPO4-11 with the crystallinity degree close to 100 %. The developed method for preparation of these disperse molecular aluminophosphate sieves AlPO4-11 is a step to crystallization of silicoaluminophosphates SAPO-11 that are promising Russian catalysts for industrial processes of hydroisomerization of n-paraffins used for manufacturing of Arctic diesel fuel, III group oils and isomerization of butenes.