Patent GB-1059879-A (GB)
Title: Process for separating straight-chain hydrocarbons from a mixture thereof with branched chain and/or cyclic organic compounds
IPC: C10G25/03
Filed: 1965-01-25
Abstract: Straight chain hydrocarbons are separated from a kerosene also containing branched chain and/or cyclic hydrocarbons by adsorbing the straight chain hydrocarbons on a molecular sieve, followed by desorption using a straight chain hydrocarbon having at least 8 carbon atoms but less than that of the lowest boiling adsorbed hydrocarbon, both adsorption and desorption being carried out at temperatures at least 40 DEG  C., preferably 50 DEG  C., above the dew point of the kerosene at the prevailing pressure and below the critical temperature of the highest boiling component. Advantageously, the temperature and pressure of adsorption and of desorption are the same.  Adsorption is preferably carried out at a temperature higher than the critical temperature of the desorbent. In the separation of straight chain C11-C15 paraffins from a kerosene fraction using, e.g. a zeolite molecule sieve having a pore size of about 5A angstrom units, adsorption and desorption temperatures are above 330 DEG  C. at pressures of at least 3 atmospheres absolute. The sieve may be saturated with desorbent, before the adsorption step, and before desorption, a purge gas, e.g. nitrogen or the desorbent may be passed through the bed in the same direction as the initial mixture. The desorbent is passed in the opposite direction. The product effluent and reject effluent are separately worked up, e.g. by distillation to recover the desired straight chain hydrocarbons and desorbent for recycling.  Feed from source 1 is heated and passed through a bed of molecular sieve in zone 13 or 15, the other being desorbed.  The effluent is separated in fractionator 22 to remove and recycle desorbent displaced from the sieve. Desorbent from source 27 is heated and passed through the bed in the opposite direction to feed and separated from desorbed n-hydrocarbons in fractionator 50. Specified zeolites are chabazite, phacolite, gmelinite, harmotome, phillipsite, clinoptilolite and erionite.ALSO:Straight chain hydrocarbons are separated from a kerosene also containing branched chain and/or cyclic hydrocarbons by adsorbing the straight cain hydrocarbons on a molecular sieve, followed by desorption using a straight chain hydrocarbon having at least 8 carbon atoms but less than that of the lowest boiling adsorbed hydrocarbon, both adsorption and desorption being carried out at temperatures at least 40 DEG C., preferably 50 DEG C. above the dew point of the kerosene at the prevailing pressure and below the critical temperature of the highest boiling component. Advantageously, the temperature and pressure of adsorption and of desorption are the same.  Adsorption is preferably carried out at a temperature higher than the critical temperature of the desorbent. In the separation of straight chain C11-C15 paraffins from a kerosene fraction using e.g. a zeolite molecule sieve having a pore size of about 5 , adsorption and desorption temperatures are above 330 DEG C. at pressures of at least 3 atmospheres absolute.  The sieve may be saturated with desorbent, before the adsorption step, and before desorption, a purge gas, e.g. nitrogen or the desorbent may be passed through the bed in the same direction as the initial mixture.  The desorbent is passed in the opposite direction.  The product effluent and reject effluent are separately worked up, e.g. by distillation to recover the desired straight chain hydrocarbons and desorbent for recycling.  Feed from source 1 is heated and passed through a bed of molecular sieve in zone 13 or 15, the other being desorbed.  The effluent is separated in fractionator 22 to remove and recycle desorbent displaced from the sieve.  Desorbent from source 27 is heated and passed through the bed in the opposite direction to feed and separated from desorbed n-hydrocarbons in fractionator 50. Specified zeolites are chabazite, phacolite, gmelinite, harmotome, phillipsite, clinoptilolite and erionite.