Propene Oligomerization and Xylene and Methyl-Pentene Isomerization over SAPO-11 and MeAPSO-11

Abstract

The molecular sieves SAPO-11 and MeAPSO-11, where Me = Co, Fe, Mn and Ni, were synthesized and the acidity of these catalysts and modified forms thereof tested using the isomerization of m-xylene and 2-methyl-2-pentene (2M2P) as probe reactions. The activity of the catalysts for high pressure propene oligomerization was also evaluated. The modifications included steaming, acid washing, metal impregnation, silanization, pelletization and extrusion. In the conversion of m-xylene the catalysts all showed the high para/ortho ratio expected for 10MR structures. In the case of 2M2P isomerization the ratio of methyl shift products (c/t-3M2P) to double bond shift (c/t-4M2P) indicated the presence of strong acid sites. In both these reactions diffusional resistances due either to the presence of non-framework intraparticular matter or to amorphous acidic material on the external surface of the crystallites masked the activity of the catalysts. This was indicated by the unusually high extent of disproportionate of the m-xylene and the poor correlations between the activity and the ammonia-TPD results. SAPO-11 modified by mild steaming yielded a remarkably high catalyst utilization value of over 1000 g liquid/g-catalyst for propene oligomerization. More than 50% of the reaction products were dimers of propene.