June 25, 1963 C. A. JUDICE TAL WEAK SULFURIC ACID PROCESS FOR CONVERTING 3,095,458 ETHYL ETHER TO ETHANOL Filed May 14, 1959 d Carlton Alexander Judice r Louis Eorl Pirkle InVentors B y drov-1/ AttornevPotent 3,095,458 United States Patent Office Patented June 25, 1963 2 a temperature in the range of 350 F. to 450 F. and is 3,095,458 WEAKSULFURECACID PROCESS FOR CON. introduced under a pressure of about 150 to 200 p.s.i.g. WERTENG RETHY, ETHER TO ETHANOL The steam can be introduced directly into the reaction Carlton Alexander Judice and Louis Earl Pirkle, Baton Zone. However, injection immediately after the ether Rouge, La., assignors to Esso Research and Engineer 5 acid mixing and prior to entry into the reaction zone is ing Company, a corporation of Delaware much more satisfactory. In a continuous process a Filed May 14, 1959, Ser. No. 813,305 constant ratio of steam to acid and ether is easier to 4 Claims. (C. 260-639) maintain when steam is injected into the feed line to the reactor than where the steam and ether-acid are fed sepa This invention relates to an improved process for con 10 rately into the mixture of reactants, intermediates and verting aliphatic ethers to alcohols by hydration with products in the reaction zone. The ether-acid mixture sulfuric acid wherein the heat of reaction is supplied by can thus be contacted immediately after mixing. These the direct admission of steam into the reaction mixture. factors tend to reduce over-conversion to hydrocarbons, In particular, this invention relates to an improved a problem in all processes known to the art. The instant process for converting ethyl ether to ethanol by thorough 5 process provides many other advantages. By effecting ly mixing ethyl ether with a sulfuric acid of about 63 to the necessary heat exchange through direct contact with 70 wt. percent concentration at moderate temperatures steam, the conventional heat exchange equipment may be and injecting steam under elevated pressures directly into eliminated. Another saving not insignificant in a large the ether-acid mixture and to methods for recovering the scale continuous process is afforded by the direct heating resulting ethanol. 20 with steam in that the heat of dilution of sulfuric acid More particularly, this invention relates to a process is utilized accounting for about 10 to 15 F. of the re for converting ethyl ether to ethanol wherein an ethyl quired temperature rise. ether feedstock of 90 to 100% purity is passed under The conversion to ethanol is controlled by residence flow control through a mixing zone wherein said ether time, ether-acid mole ratio, temperature of operation and is contacted and intimately mixed with a 63 to 70 wt. 25 acid concentration after steam dilution. The pressure in percent sulfuric acid in a ratio of 0.5 to 0.7, preferably the reaction vessel is not independently important but 0.6, mole of ether per mole of H2SO4 at a temperature rather is governed by the temperature of the reacting of less than about 200 F. and preferably in the range (mixture since a sufficient pressure must be employed to of 100 to 200° F. and heated to the temperature of maintain the reacting mixture substantially in a liquid reaction by injecting steam under a pressure of 150 to 30 state. The residence time may vary from about 1 to about 200 p.s.i.g. directly into the ether-acid mixture prior 4 hours. Residence time in the range of 3 to 4 hours is re to its entry into the reaction Zone. quired at the minimum reaction conditions with a 0.6/1 The production of ethyl alcohol by the hydration of ether to acid mole ratio, i.e. at a temperature of 230 ethylene in the presence of an acid catalyst is accom F. and an acid strength after steam dilution of 60 wt. panied by the formation of approximately 10 to 25% 35 percent HaSO4, to yield about 30% conversion based on of diethyl ether as a by-product. When market demand ether fed to the reactor. When a temperature of 270 F. for ethanol is unusually high or a lag occurs in ether is employed with a 65 wt. percent acid, after steam dilu demand, the ether may be converted to alcohol. tion, at the same ether-acid raito a residence time of One process for such conversion involves passing ether about 1 hour will yield a 60% conversion. All inter and water under superatmospheric pressures ranging up to 40 mediate conditions are operable and provide an efficient 200 atmospheres over a hydration catalyst containing a process. Lower ether to acid ratios require excessive resi difficultly reducible hydrous oxide such as alumina, silica, dence times and excessive acid requirements. Higher etc. The economics of such processes, however, have not ether to acid ratios result in a two-phase operation with been suitable for commercial use. resultant low conversion. At temperatures higher than It is well known in the art that ethyl ether can be 270° F. appreciable conversion to hydrocarbons occurs. hydrated to ethanol with dilute sulfuric acid. One such At temperatures lower than 230 F. and/or acid strengths, process is operated at temperatures in the range of 200 after steam dilution, below 60 wt. percent low conver to 300° C. and pressures in the range of 225 to 3000 sions result. The amount of steam introduced should p.si. with a 10 wt. percent sulfuric acid. Such processes be controlled so as not to reduce the acid strength below have proven unattractive for commercial use due to low 50 about 60 wt. percent. For example, when starting with yields of ethanol and undesirably high conversions of al a reacting mixture at 150 F. which contains 0.6 mole cohol to hydrocarbons. In processes of this type various of ether per mole of acid, with the acid present in the arrangements of heat exchange equipment requiring ex form of 68 wt. percent H2SO4, sufficient heat can be sup pensive non-corrosive materials are employed to bring the plied by 200 p.si.g. of saturated steam, throttled to about reaction mixture to the temperature of reaction. If steam 55 150 p.si.g., to bring the reacting mixture up to about is employed at all it is introduced into the reaction Zone 250° F. without reducing acid strength below 63 to 65 after or simultinaeously with independently heated re wt. percent HSO4. actants. The reaction vessel must be adapted to withstand ele It has now been discovered that high conversions of vated pressures of the order of 150 to 250 p.s. i. and ether to ethanol can be effected if the ether and acid are 60 temperatures up to 300 F. or higher. The apparatus thoroughly mixed to form a homogeneous mixture in a must be acid resistant and may be made of suitable metal controlled ether to acid mole ratio of about 0.5 to 0.7:1 alloys such as chrome steels and the like, or lined with and the temperature of the mixture raised to the tempera such alloys, or with enamel, carbon, karbate, stone ware, ture of reaction by the introduction of high pressure acid resistant brick, and the like. steam directly into such mixture preferably prior to the 65 The reaction mixture upon leaving the reactor con entry of such mixture into the reaction Zone. The re tains reacted ether present as ethanol and ethyl sulfate. action is carried out at a temperature in the range of The product stream is steam stripped, further hydrolyzed, about 230 to 270 F. To achieve this temperature steam. and neutralized with a caustic wash. This is followed is injected directly into the mixture. The ratio in lbs. 70 by a recovery of both ether and ethanol by a novel wash of steam/lbs. of acid--ether is in the range of 0.05 to process. Acid is recovered from the stripping operation 0.15 with about 0.1 preferred. The steam employed has and both ether and acid are recycled. 3,095,458 3 4. The invention may be more easily understood by refer separator 32 where a liquid gas disengagement is again ring to the accompany drawing representing a preferred effected. The condensate from separator 32 is passed embodiment of the invention. via line 33 to separator 29. Any uncondensed vapors An ethyl ether feedstock of 90 to 100 vol. percent in separator 32 are passed via line 34 to a vent gas purity is passed via line 1 through a flow control device scrubber 35 and contacted with water introduced via line represented by valve 2 into a mixing zone 3 where it is 36 to remove trace amounts of ether and ethanol which contacted and intimately mixed with a 63 to 70 wt. per have not been condensed. The overhead vapors from cent sulfuric acid introduced into mixing zone 3 via line scrubber 35, removed via line 37, are small in volume 5 under flow control here represented by valve 4. The and contain mainly ether and hydrocarbon impurities, ether and acid are mixed in a ratio of 0.5 to 0.7, prefer 0 e.g. ethylene formed in the reaction or present as an ably about 0.6, mole of ether/mole of H2SO4 at a tem impurity in the feedstock. The bottoms stream from perature in the range of 100 to 200 F. The resulting scrubber 35 contaniing water with small amounts of mixture is passed from mixing zone 3 into line 6.