Patent GB-543046-A (GB)
Title: Improvements relating to the manufacture of saturated hydrocarbons by alkylation
IPC: C07C2/62
Filed: 1940-01-12
Abstract: 543,046. Acyclic hydrocarbons: STANDARD OIL DEVELOPMENT CO. Jan. 12, 1940, Nos. 722 and 723. Convention dates, Feb. 27, 1939, and April 13, 1939. [Class 2 (iii)] In the production of normally liquid saturated hydrocarbons boiling within the gasoline range by re-action of a mixture containing both iso- and normal paraffins with a monoolefin or a diolefin in presence of an alkylation catalyst, the re-action mixture is substantially freed from admixed catalyst and is fractionated to separate substantially only isoparaffins, the residue being then separately fractionated to remove substantially only the normal paraffin content thereof. The isoparaffins so separated are, advantageously, returned to the alkylation zone. Specified catalysts are concentrated mineral acids, e.g. sulphuric, phosphoric or tetraphosphoric acid, metal halides, with or without addition of alkyl halides, acid activated clays, boron trifluoride and sodium aluminium halide . complexes. Feed stock containing the re-actants may be normally gaseous (C 4  cut) or normally liquid (C 5  cut).. The process enables a separation to be effected of isoparaffins from normal paraffins in a C 4  or C 5  fraction containing olefines more easily than is possible by simple fractionation. Fig. 1 is a diagram of plant for the treatment of a C 4  cut. The feed stock, with, if necessary, additional isobutane, is supplied through pipes 2, 4 to cooler 6 and passes thence, preferably at 35-70‹ F. to dispersion device 9 in re-actor 8 fitted with baffle plates 10 and containing the acid catalyst. The resulting mixture passes through pipe 11 and thence the major part by valve 15, pipe 14, valve 17 and pipe 16 to the pipe 4 for return through cooler 6 to re-actor 8, and the minor part by valve 13 and pipe 12 to a settler 18 whence, the acid is withdrawn through pipe 20 and valve 21 and either returned to the re-actor 8 by pipes 24, 16 and 4 or   withdrawn through valve 26 and pipe 25. Hydrocarbons, advantageously under sufficient pressure to maintain them in the liquid phase, and carrying entrained acid, pass to a second settler 19 whence most of this remaining acid is similarly withdrawn through pipe 22. The hydrocarbons pass through pipes 12c and 33 to a vessel 29 for admixture of dilute alkali supplied through valve 34 and pass thence by pipe 35 to a settler 37 whence the spent alkali is withdrawn and the neutralized hydrocarbons pass by pipe 38 to a tower 40 under a pressure of 75 lb. per sq. inch and of which the temperature at the top is 100-130‹ F. and at the bottom 150-200‹ F. From the top gases, mainly isobutane, are either returned by pipe 45 to the feed line 2 or withdrawn through pipe 44. The effluent from the bottom of tower 40 passes by pipe 41 to a tower 47 under a pressure of about 50 lb. per square inch and of which the temperature at the top is 100-130‹ F. and at the bottom 280-330‹ F. Most of the normal butane is removed from the top through line 48 and may be subjected to catalytic dehydrogenation to produce olefines or to catalytic isomerization to produce isobutanes which, if desired, may be dehydrogenated to isobutylene, all products suitable for use in the main process. The effluent from the bottom of tower 47 passes by pipe 50 to a tower 52, under atmospheric pressure, and of which the temperature at the top is about 240-280‹ F. and at the bottom about 280-330‹ F. Fractionation in this tower may produce, for example, light products - withdrawn from the top by pipe 53 and, if desired, re-cycled, intermediate products from a trap-out tiay 55 and a bottom effluent which may be re-cycled to line 4 through pipe 58. Make-up acid may be supplied through line 30. Fig. 2 is a diagram of plant for the treatment of a C 5  cut delivered through pipe 105 from a fractionating tower 101 to an alkylation unit 107 to which is also supplied isobutane or other suitable isoparaffin through line 108. The alkylation product passes to a tower 109 maintained under pressure and temperature conditions suitable for withdrawal from the top of isobutane, to be returned by pipes 110, 108 to the alkylation unit, and from the bottom of an effluent passing to a series of fractionating towers 112, 115, 118 maintained under pressure and temperature conditions such that isopentane is mainly withdrawn from the top of tower 112, normal pentane mainly from the top of tower 115, a C 8  fraction from the top and a C 9  fraction from the bottom of tower 118. Cyclopentane may be recovered as a side stream from tower 115 or from the top of a tower interposed between towers 115 and 118.