Patent GB-614165-A (GB)
Title: Improvements in a process for the hydration of olefines
IPC: C07C29/04
Filed: 1945-09-18
Abstract: <PICT:0614165/IV(b)/1> A process for the preparation of alcohols, by the catalytic hydration of olefines by means of aqueous sulphuric acid of a concentration below that which would give rise to substantial secondary reaction, comprises cycling said aqueous sulphuric acid through two intercommunicating reaction zones, one subjected to super-atmospheric pressure and constituted wholly or in part by an emulsion pump of the mammoth-type, as hereinafter defined, and the other subjected to substantially atmospheric pressure, said emulsion pump being supplied under pressure with and operated by the olefine to be hydrated, whereby olefine is dissolved in said aqueous acid, and alcohol so formed being removed from the aqueous sulphuric acid while in the reaction zone subject to substantially atmospheric pressure.  The emulsion pump comprises a system in which two or more air-lifts are arranged in series, an air-lift being an arrangement wherein a gas is fed under pressure at the foot of an enclosed column of liquid, the unemulsified gas issuing from the head of the first column being passed to the foot of the next column and so on, whereas the liquid or emulsion issuing from the head of the last column is passed to the foot of the penultimate column, and so on.  The emulsion pump may comprise the whole of the higher pressure zone, the hydrating liquid then flowing direct to the lower pressure zone after the release of the pressure; alternatively, the liquid may first be led to another vessel at superatmospheric pressure for reaction with more olefine.  Alcohol is recovered by passing a forced current of olefine through the hydrating liquor, conveniently in a closed cycle, during which a further quantity of alcohol may be formed, the issuing olefine being scrubbed with an aqueous medium or subjected to condensation to isolate the alcohol.  As shown in Fig. 2, the emulsion pump comprises a series of emulsifiers E1-4 connected with gas-removing vessels D1-4.  A container 9 supplies compressed olefine to emulsifier E4 while hydrating liquid from tank B is introduced into emulsifier E1 via line 5.  The mixtures of olefine and hydrating liquid pass from the emulsifiers up the pipes r1-4 into separator vessels D1-4, after which the olefine is led to the preceding emulsifier and the liquid to the following emulsifier.  Ultimately, hydrating liquor saturated with dissolved olefine leaves the pump via vessel D4 and pipe 34, and unused olefine leaves via vessel D1 and passes through a separator 29 and a gasometer 13 to container 9. When a difficultly hydratable olefine such as ethylene is used, the hydrating liquor is led by line 34 to a reaction tank A wherein it is further reacted under pressure with olefine supplied via line 35. The liquor from tank A next passes through a pressure reducer 8 to distillation tank B where the alcohol formed is removed by a forced current of olefine circulated through the liquid by means of a fan 18, the olefine and entrained alcohol being passed through a scrubber 15 for removal of alcohol in aqueous solution which is led away to the distillation unit 22.  When the selected olefine is readily hydrated, the supplementary reaction zone <PICT:0614165/IV(b)/2> may be omitted, the hydrating liquor issuing from the emulsion pump then being sent direct to the distillation tank B via line 34 and a pressure reducer.  Fig. 1 (not shown) illustrates the modified apparatus for this process, of which an example is given wherein propylene is hydrated to isopropanol by means of 60 per cent sulphuric acid.  The olefines may be used pure or in admixture with inert gases such as saturated hydrocarbons.  The Specification as open to inspection under Sect. 91 relates broadly to the hydration of olefines with a hydrating liquor wherein olefine dissolution and removal of the resulting alcohol are performed separately in intercommunicating vessels, one being at superatmospheric pressure and the other at substantially atmospheric pressure.  Examples describe the hydration of propylene with 60 per cent sulphuric acid and of ethylene with 73 per cent sulphuric acid containing sodium sulphate, using the apparatus shown in Fig. 1 (Cancelled).  The olefine is fed from container 9 under pressure to an injector 7, thereby forcing hydrating liquor from tank B into tank A.  The liquor saturated with olefine flows from tank A into tank B at atmospheric pressure via the reducer 8 and line 6.  The formed alcohol is recovered in tank B in the manner described above.  This subject-matter does not appear in the Specification as accepted.