Patent GB-560254-A (GB)
Title: Catalytic isomerization and alkylation of hydrocarbons
IPC: C07C2/54
Filed: 1942-05-20
Abstract: <PICT:0560254/IV/1> In the isomerization or alkylation of saturated hydrocarbons with a fluid catalyst comprising a plurality of molten metal halides of different solubility in the said hydrocarbons, the latter are contacted with spent or partially spent catalyst to dissolve at least part of the more soluble salt or salts therefrom before treatment under isomerization or alkylation conditions with the active fluid catalyst.  Suitable catalysts comprise one or more aluminium halides, e.g. chloride and/or bromide, with one or more halides of Li, Na, K, As, Zr, Nb, Mn, Pd, Sn, Sb, Hf, Ta, V, Cb, W, Tl, Pb, Bi, Fe, Co, Ni, S, Se or Te, especially AlCl3 + SbCl3 + halide of Na, K or Zn.  Eutectic mixtures of Al and other halides are effective.  The hydrocarbons treated may be paraffins of 4-9 carbon atoms or commercial mixtures containing them from which unsaturated hydrocarbons have been substantially removed, or naphthenes such as methyl cyclopentanes or cyclohexanes.  Butane is fed by pump 11 through dryer 12 and heater 14 to an extraction column 15 where it meets a downward stream of spent catalyst fed by pipe 41 from reactor 18.  This comprises concentric partitions 19, 20 defining a mixing zone 21 and an annular space 22 communicating via openings 23.  The butane enters by line 16 with hydrogen chloride and, if desired, hydrogen, and is mixed with a catalyst consisting of 76-97 mol per cent SbCl3 and 24-3 mol per cent AlCl3. Temperature may be up to 200 DEG  C., e.g. 60-120 DEG  C., and pressure sufficient to liquefy butane, e.g. 125-500 lbs. gauge.  Reaction product with admixed catalyst is withdrawn from the top of the annular space 22 by line 29 to vaporizer 30 where catalyst is separated and fed by line 35 to reactor 18 while reaction products leave rectifier 51, in which entrained SbCl3 is removed and are cooled in 54 to condense butanes. These are treated in high-pressure stripping column 59 to remove HCl and pass to fractionator 72 where normal butane, at least part of which is recycled by lines 77, 82, is separated from isobutane which is recovered as overhead.  Spent catalyst comprising sludge concentrates in the lower part of annular space 22 and is fed by line 41 to column 15 preferably at such a rate that there is no accumulation.  In column 15 the hydrocarbon feed dissolves the more soluble salt components and the insoluble sludge is p  eliminated through line 42.  With the butane feed preheated to 80 DEG  C. in an example, more than 99 per cent of the extracted catalyst was SbCl3. To replace AlCl3 removed as sludge, catalyst leaving vaporizer 30 may be periodically passed through a drum 47 containing AlCl3.  In a modification, Fig. 2 (not shown), the reactor 18 is replaced by a series of chambers through which the butane flows upwardly against a counter-current of catalyst.  The reaction products leaving the top of the last chamber contain dissolved catalyst, especially the more soluble SbCl3 which is recovered in the vaporizer as before.  The sludge is withdrawn from the bottom of the first chamber and passed to the extraction column 15.  With a more rapid flow of catalyst, this sludge contains considerable unspent catalyst and part is recirculated.