| 摘要 |
A cyclic vapour phase process for the separation of straight-chain hydrocarbons from mixtures, for example a petroleum fraction boiling in the range 150-400 DEG C., by means of a 5A molecular sieve comprises successive absorption, purge, and desorption stages, wherein the pressure in the absorption stage is 50-150 p.s.i. below the dew point pressure. Non-absorbed hydrocarbons are removed during the purge stage, and straight chain hydrocarbons recovered during the desorption stage. The feedstock may be mixed with a diluent of lower boiling point than the lowest boiling component of the mixture, for example nitrogen, the ratio of nitrogen to feedstock preferably being 0.5:1 to 5:1, which diluent material may also be employed as the purge material. In one form, wherein more than two absorbers are used, the effluent from the absorber being purged may be employed as the diluent. The desorption step may be effected by elution with a straight chain hydrocarbon having a lesser number of carbon atoms than the lowest boiling straight chain hydrocarbon in the feedstock, for example butane or pentane. The absorption stage is preferably operated at 300-400 DEG C., 50-300 p.s.i.g., LHSV 0.1-5. All the stages may be operated isothermally and isobarically. Specification 994,441 is referred to.ALSO:A cyclic vapour phase process for the separation of straight-chain hydrocarbons from mixtures, for example a petroleum fraction boiling in the range 150-400 DEG C., by means of a 5 molecular sieve comprises successive absorption, purge, and desorption stages, wherein the pressure in the absorption stage is 50-150 p.s.i. below the dew point pressure. Non-absorbed hydrocarbons are removed during the purge stage, and straight chain hydrocarbons recovered during the desorption stage. The feedstock may be mixed with a diluent of lower boiling point than the lowest boiling component of the mixture, for example nitrogen, the ratio of nitrogen to feedstock preferably being 0,5 : 1 to 5 : 1, which diluent material may also be employed as the purge material. In one form, wherein more than two absorbers are used, the effluent from the absorber being purged may be employed as the diluent. The desorption step may be effected by elution with a straight chain hydrocarbon having a lesser number of carbon atoms than the lowest boiling straight chain hydrocarbon in the feedstock, for example butane or pentane. The absorption stage is preferably operated at 300-400 DEG C., 50-300 p.s.i.g., LHSV 0,1-5. All the stages may be operated isothermally and isobarically. Specification 944,441 is referred to. |
