The role of pore topology on the behaviour of FCC zeolite additives

A large variety of zeolite topologies including: large pore tridirectional (Beta), large pore unidirectional (Mordenite, SSZ-24), bidirectional 10 member ring pores (MRP) (ZSM-5), bidirectional 10 x 8 MRP (Ferrierite), tridirectional with connected 12 and 10 MRP (CIT-1), bidirectional with 12 MRP connected by 10 MRP (NU-87), tridirectional with 10 x 11 x 12 MRP (NU-86), and finally 10 MRP, and independent 12 MR cavities connected by 10 MR windows (MCM-22), have been studied as catalysts for the cracking of a gasoline range model molecule (n-heptane). Kinetic and decay constants as well as selectivity parameters such as paraffin/olefin, i-C-4/n-C-4, i-C-5/n-C-5, C-3/C-4 and C-2/C-5 have been used to discuss the behaviour of the above zeolite structures as potential FCC additives. (C) 1999 Elsevier Science B.V. All rights reserved.