A method for the isomerization of paraffins from a hydrocarbon fraction with distillate boiling range.

摘要

The present invention includes a process and catalyst composition for paraffinic isomerization of a hydrocarbon feedstock which has a paraffin content having no more than 20 carbon atoms per molecule. The feedstock is contacted with a crystalline aluminosilicate zeolite catalyst having pore openings defined by: (1) a ratio of sorption of n- hexane to o-xylene, on a volume percent basis, of greater than about 3, which sorption is determined at a P/P.sub.o of 0.1 and at a temperature of 50° C. for n-hexane and 80° C. for o-xylene and (2) by the ability of selectively cracking 3-methylpentane (3MP) in preference to the doubly branched 2,3-dimethylbutane (DMB) at 1000° F. and 1 atmosphere pressure from a 1/1/1 weight ratio mixture of n-hexane/3- methyl-pentane/2, 3-dimethylbutane, with the ratio of rate constants k. sub.3MP/ k.sub.DMB determined at a temperature of 1000° F. being in excess of about 2, e.g., ZSM-22, ZSM-23, AXM-35 and mixtures thereof, in combination with a Group VIII metal, and having a zeolite SiO.sub.2 /Al. sub.2 O.sub.3 ratio of at least about 20:1 at a temperature and pressure suitable for isomerization.