| 摘要 |
The hydration of olefines is effected by means of water vapour in presence of aqueous sulphuric, phosphoric, sulphonic, or other strong acids in the free liquid phase at pressures substantially above atmospheric. Sulphuric acid may be of 40-80 per cent strength for ethylene, and 45-50 per cent for propylene, and phosphoric acid may be of 85-90 per cent or more for ethylene and 60-85 per cent for propylene. The temperatures may approach the boiling-points of the acids, for instance with sulphuric acid 130-160 DEG C. and with phosphoric acid 200-300 DEG C. are suitable. The pressure may be 50 atmospheres or even 250 atmospheres or higher. The proportion of steam is preferably chosen so as to maintain the acid concentration constant; usually 10-20 molecules of olefine to 1 of steam is suitable. The acid may contain metals, salts, or other catalytic agents, such as silver, calcium, lead, iron, mercurous and ferrous ammonium sulphates, silver, and copper. The acid may be treated with the olefine alone until practically saturated before passing in the mixture of olefine and steam. This preliminary absorption may be below about 80 DEG C. for ethylene and 10-20 DEG C. for propylene and higher olefines, and the pressure at this stage may be any suitable pressure, for instance atmospheric or raised pressure. In an example a mixture of ethylene and steam in the molecular proportion 18 : 1 is passed at 50 atmospheres pressure through sulphuric acid of 75 per cent at 165 DEG C. at 8000 litres per hour per litre of acid (calculated at N.T.P.). The concentration of the acid falls at first owing to the formation of ethyl sulphuric acid and alcohol, but is afterwards maintained at about 60-63 per cent. The alcohol is separated from the unchanged ethylene which is then returned to the process. In another example, a mixture of ethylene and steam in the molecular proportion 14 : 1 is passed at 50 atmospheres through phosphoric acid of 90 per cent at space velocity 6000 at 240 DEG C.
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