GB403402A - Improvements in or relating to the production of aliphatic ethers - Google Patents

Abstract

<PICT:0403402/IV/1> Ethers are produced by passing the vapours of the corresponding alcohol over a dehydrating catalyst and passing the reaction products preferably in vapour form, into a rectifying column in which the alcohol and water are condensed while the ether passes off as vapour and is separately condensed. Preferably the alcoholic condensate is treated in a second column to separate the alcohol which is returned to the process. The alcohol vapour may be preheated by heat exchange. The reaction temperature may be 175--500 DEG C. for methanol, and the pressure may be 15 atmospheres, but pressures up to 200 atmospheres may be used. The space velocity (at N.T.P.) may be 200--30000 per hour, but preferably about 5000. Suitable catalysts are alumina, partially hydrated alumina (obtained by heating the hydroxide at 300 DEG C.) partially hydrated titanium oxide, barium oxide, silica gel, basic aluminium sulphate, and aluminium phosphate. When methanol is employed, all apparatus with which it contacts prior to its conversion, should be composed of or lined with aluminium or other material which does not catalyze its decomposition to carbon monoxide. In the apparatus shown the liquid alcohol is supplied at 1 with recirculated alcohol from a pipe 30 and is passed through a pump 2 and pipe 3 to a heat exchanger 4 where it is vaporized by the heat of the reaction products which enter at 9 and leave at 10. The alcohol vapour then passes to a second preheater 6 which may be heated electrically to about the reaction temperature, and then by a pipe 7 to the reaction chamber 8. The reaction products pass by pipe 9, heat exchanger 4 and pipe 10 to a cooler 18 or its byepass 14 and thence by a pipe 17 to a distillation column 19 having heating coils 20. Ether passes off by a pipe 25 to a condenser 26 and is withdrawn at 27. The liquid effluent from the column 19 is passed by a pipe 21 to a column 22 from which the alcohol is returned via the pipe 30. The uncondensed vapours from the catalytic synthesis of methanol may be employed for this process, the preheaters then being unnecessary; the pressure is reduced to the desired extent before admitting to the reaction vessel.