Method for separating straight chain hydrocarbons using zeolites having large crystals

A method for separating straight chain hydrocarbons from a hydrocarbon fraction having straight chain hydrocarbons, nonstraight chain hydrocarbons, and a sulfur compound comprising the steps of contacting said hydrocarbon fraction with a 5A zeolite which selectively absorbs said straight chain hydrocarbons to the substantial exclusion of said nonstraight chain hydrocarbons, said hydrocarbon fraction having more than about 800 and up to about 9000 parts per million by weight of total sulfur including more than about 15 and up to about 200 parts per million of mercaptan, said zeolite having crystals of an average size larger than about 700 angstroms, said crystal size being measured along one edge of the zeolite crystal;

• desorbing said straight chain hydrocarbons from said zeolite;
• regenerating said zeolite after one or more separating and desorbing steps;
• and during said steps substantially preventing said hydrocarbon fraction from contacting an apparatus not resistant to attack by said sulphur compound.