Separation of mixtures

Claim 1

AN ISOTHERMAL PROCESS FOR THE SEPARATION OF STRAIGHTCHAIN HYDROCARBONS FROMPETROLEUM FRACTIONS BOILING IN THE C10-C20 RANGE AND PRETREATED TO REDUCE THE SULFUR CONTENT TO A VALUE NOT EXCEEDING 0.1% WEIGHT COMPRISING CONTACTING THE FRACTION WITH A NUMBER OF FIXED BEDS OF A 5 A. MOLECULAR SIEVE IN A FIRST STAGE TO ABSORB STRAIGHTCHAIN HYDROCARBONS, CONTACTING THE SIEVE WITH A PURGING MEDIUM IN A SECOND STAGE TO REMOVE MATERIAL ADSORBED ON THE SURFACE OF THE SIEVE OR HELD INTERSTITIALLY BETWEEN SIEVE PARTICLES, DESORBING THE ABSORBED HYDROCARBONS IN A THIRD STAGE USING A DESORBING MEDIUM SELECTED FROM THE GROUP CONSISTING OF N-PENTANE AND N-BUTANE, ALL THREE STAGES BEING IN THE VAPOUR PHASE AND AT A TEMPERATURE IN THE RANGE OF 300-450*C., THE PRESSURE IN THE DESORPTION STAGE BEING AT LEAST EQUAL TO THE PRESSURE IN THE ABSORPTION STAGE, THE RATIO OF ABSORPTION, PURGE AND DESORPTION STAGES AT ANY POINT OF TIME IS 1:1:2 AND THE RATIO OF THE LENGTH OF TIME OF THE ABSORPTION, PURGE AND DESORPTION STAGES IS ALSO 1:1:2 AND RECOVERING THE DESORBED STRAIGHT-CHAIN HYDROCARBONS IN A PURITY OF AT LEAST 95% WEIGHT.