Use of modified 5-7 a pore molecular sieves for isomerization of hydrocarbons

A process for dewaxing a hydrocarbon feed to produce a dewaxed lube oil, the feed including straight chain and slightly branched chain paraffins having 10 or more carbon atoms, comprising:

• contacting the feed under isomerization conditions with an intermediate pore size molecular sieve having a crystallite size of no more than about 0.5.mu., having pores with a minimum pore diameter of at least 4.8.ANG. and with a maximum pore diameter of no more than 7.1.ANG., the catalyst 1) having sufficient acidity so that 0.5 g thereof when positioned in a 1/4 inch internal diameter tube reactor converts at least 50% of hexadecane at a temperature of 370.degree. C., a pressure of 1200 psig, a hydrogen flow of 160 ml/min and a feed rate of 1 ml/hr and 2) exhibiting 40 or greater isomerization selectivity which is defined as:
• ##EQU3## when used under conditions leading to 96% conversion of hexadecane, the catalyst including at least one Group VIII metal, the contacting being carried out at a pressure from about 15 psig to about 3000 psig.