Hydroisomerization of pentane, hexane, and heptane for improving the octane number of gasoline

The hydroisomerization of n-heptane to dibranched and tri-branched products for producing high octane gasoline has been studied using unidirectional 1 2 Membered Ring (MR) zeolites with different pore diameters, and zeolites w ith other pore topologies including one with connected 12 x 10 MR pores and two tridirectional 12 MR zeolites. Besides the pore topology, the crystall ite size of the zeolite was seen to be of paramount importance for improvin g activity and selectivity. In a second part of the work, a Light Straight Run naphtha including n-pentane and n-hexane and another feed containing n- pentane, n-hexane, and n-heptane have been successfully isomerized using a nanocrystalline Beta (BEA) zeolite. This can be a favourable alternative to the commercial zeolite catalyst based on mordenite (MOR), especially when n-heptane is present in the feed. (C) 1999 Academic Press.