Disproportionation of Ethylbenzene over Sapo-40

SAPO-40, a silicoaluminophosphate with a structure not topologically related with any aluminosilicate zeolite, was synthesised for the first time in 1984 by Lok and co-workers [1]. Recently, a synthesis procedure leading to pure SAPO40 was developed and the structure of this material was established by crystallographic methods. The framework topology (designated AFR by the International Zeolite Association) consists of saddle-shaped 12-membered rings forming channels parallel to the c-axis and 8-membered rings channels parallel to the b-axis. These channels, with free diameters of 6.7 and 3.8 Å respectively, intersect to form a two-dimensional system. The third direction is blocked by a wall of 4and 6rings [2]. The acidity of this material has been related with the silicon content and the distribution of this element in the framework. The high activity of SAPO-40 in the cracking of n-heptane [3] reflects these two factors, the second, probably being the most important.