Patent GB-446781-A (GB)
Title: Improvements relating to the hydration of olefines
IPC: C07C29/04
Filed: 1935-02-15
Abstract: <PICT:0446781/IV/1> <PICT:0446781/IV/2> A process for the hydration of olefines comprises the continuous passage of the olefine countercurrent to a dilute aqueous catalytic solution at a temperature below about 350 DEG  C. and under such a super-atmospheric pressure that none of the alcohol formed in the reaction is withdrawn as vapour, water being added in sufficient amount to prevent concentration of the catalytic solution.  The concentration of the alcohol throughout the reaction zone is maintained well below equilibrium concentration in the catalytic liquor which is withdrawn.  The alcohol is recovered from the liquor by distillation, which is then recirculated.  The concentration of alcohol in the catalytic liquor may be regulated (1) by the rate of flow of the catalytic liquor through the reaction zone.  (2) By introducing into the reaction zone a liquid capable of absorbing alcohol and maintaining such liquid out of contact with the catalytic liquor, (3) By adding to the catalytic liquor an organic acid which serves to esterify a portion of the alcohol.  Among the catalysts which may be used are mineral acids such as hydrochloric and other halide acids, sulphuric acid, and phosphoric acid, organic acids such as acetic acid and oxalic acid, and metal halides such as those of cadmium, zinc, ammonium and aluminium.  Silver salts may also be used but are more effective in combination than alone. Hydrocarbon oils or turkey red oil and the like may be added to the catalytic solution to assist in absorption of the olefines.  A preferred strength of the catalytic solution is 1--10 per cent and a preferred pressure about 100 atmospheres.  Both strength and pressure however vary according to the particular catalyst used. It is also preferred that the alcohol concentration in the catalytic liquor should not substantially exceed 50 per cent of the equilibrium value.  The necessary water may be added by including steam in the gaseous stream.  This is particularly advantageous where the gases are very rich in olefines.  The apparatus must be designed to withstand attack by the catalysts used, and with sulphuric acid, a copper lined vessel is suitable, although other linings or chromium alloys may be used. In Fig. 1, gas cracked in the furnace 3, cooled in worm 4, and purified in tower 5 is compressed in the pump 10, reheated in worm 11 and mixed with superheated steam from the pipe 13 before passing to the reaction chamber 15.  The catalytic solution is introduced through line 18 and contacts with the upflowing olefine and steam mixture.  The catalytic liquor charged with alcohol is drawn off at 20, and passes through a reduction valve 21 into a recovery tower 22. The alcohol is distilled off, condensed in worm 26 and collected in receiver 27.  The alcohol free catalytic liquor is drawn off at 30 and returned to the reaction chamber.  Fig. 2 shows an alternative form of reaction tower and recovery stream. In this case two separate streams of liquor flow through the tower without mixing, the one being the catalytic liquor which promotes the formation of alcohol in the gas stream, and the other being an absorbent liquor such as petroleum oils or phenols, particularly alkyl phenols, which removes the alcohol from the gas stream.  The two streams are treated separately in towers 22 and 22<a> for the recovery of the alcohol.ALSO:<PICT:0446781/III/1> <PICT:0446781/III/2> Olefines are hydrated by being passed in conjunction with steam countercurrent to a dilute aqueous catalytic solution at a temperature below about 350 DEG  C., and under such a super-atmospheric pressure that none of the alcohol formed in the reaction is withdrawn as vapour.  One form of the apparatus used is shown in Fig. 1 in which gas cracked in the furnace 3, cooled in worm 4, and purified in the tower 5, is compressed in pump 10, reheated in worm 11, and mixed with superheated steam from the pipe 13 before passing to the reaction chamber 15.  The catalytic solution is introduced through line 18 and contacts with the upflowing olefine and steam mixture.  The catalytic liquor charged with alcohol is drawn off at 20 and passes through a reduction valve 21 into a recovery tower 22.  The alcohol is distilled off, condensed in worm 26, and collected in receiver 27. The alcohol free catalytic liquor is drawn off at 30 and returned to the reaction chamber.  Fig. 2 shows an alternative form of reaction tower and recovery stream.  In this case two separate streams of liquor flow through the tower without mixing, the one being the catalytic liquor which promotes the formation of alcohol in the gas stream, and the other being an absorbent liquor such as petroleum oils or phenols, particularly alkyl phenols, which removes the alcohol from the gas stream.  The two streams are treated separately in towers 22 and 22<a> for the recovery of the alcohol.  A small amount of an organic acid may be added to the catalytic liquor, in which case some ester is formed which is extracted with the alcohol.