| 摘要 |
Aldehydes are hydrogenated to alcohols by a continuous process in which the aldehydes are heated to hydrogenation temperatures in a heating zone and then passed to a catalytic hydrogenation zone for conversion to alcohols at elevated temperature and pressure, there being maintained an extraneous cooling fluid at a pressure above and a temperature below those obtaining in the hydrogenation zone and means provided for the admission of this fluid to the aldehyde-comprising stream passing from the heating zone to the hydrogenation zone when the temperature of this stream reaches a predetermined maximum safe value, the fluid being admitted in amounts sufficient to decrease the temperature of the flowing stream to below this safe maximum, the fluid being hydrogen or an inert fluid, e.g. water. The maximum safe temperature is that above which temperature runaway takes place in the hydrogenation zone such as occurs when the aldehyde feed is overheated in the heating zone. The process is described with particular reference to the hydrogenation of oxo aldehydes using a hydrogenator comprising a plurality of hydrogenation zones interspersed with cooling zones, the catalyst being a molybdenum, nickel, copper chromite or other hydrogenation catalyst but preferably molybdenum sulphide on activated carbon. The aldehydes, with small amounts of water to prevent secondary reaction, are fed to a heating zone from which the issuing stream at 400-550 DEG F. passes with hydrogen into the hydrogenator. The hydrogenation products are then cooled to about 120 DEG F. and the liquefied alcohols separated from unchanged hydrogen. This unchanged hydrogen is continuously circulated with make-up hydrogen in a closed system containing a compressor whereby the circulating gas is maintained at a pressure above that in the hydrogenation zone which is normally about 2500-4500 p.s.i.g. Part of this hydrogen is fed with the aldehyde into the heating zone, some is added to the heated stream from this zone and another portion is fed to the cooling zones of the hydrogenator for normal control of the reaction. The bulk, however, is available for introduction into the effluent stream leaving the heating zone whenever the effluent temperature reaches about 600 DEG F., this admission being affected automatically by a temperature recording controller automatically operating appropriate valves. In an alternative embodiment there is provided, in place of the circulating body of cooled hydrogen, a supply of water at about 60-100 DEG F., maintained under a high pressure, e.g. 3500 p.s.i.g., the admission of the water being likewise automatically controlled. Specifications 664,974 and 671,608 are referred to. |
