June 28, 1949. L. A. BANNON ETAL 2,474,568 DILUTION AND HYDROLYSIS OF DIETHYL SULFATE SOLUTIONS Filed June 11, 1946

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Za-wys /2 23a7/VMOM, 1/Y42 Ca/aaalas A. M7o/e/ea a 4. A/ Žervy fivy Patented June 28, 1949 2,474,568 UNITED STATES PATENT OFFICE 2,474,568. OLUTIONANDHYDROLYSIS OF DETHY, SULFATE SOLUTIONS Lewis A. Bannon, Baton Rouge, La., and; Charles E: Morrell, Westfield, N.J., assignors to Standa ard Oil Development Company, a corporation of Delaware Applieation June 11, 1946, Serial No. 676,078. 9, Claims: (C. 260-639) 1. 2. This, invention relates to the production of hydrolysis of the diethylistilfate:according to this by hydrolysis of extracts of: invention, it is accordingly possible to carry, re normally gaseous, olefins, and is particularly ap action)3 to virtual completion before 4 can cont. plicable to the preparation of pure ethyl alcohol. tribute large concentrations of alcohol for re When solefins such as: ethylete are absorbed in: 5 action 1. In this manner, formation of strong sulfuric acid; the: resulting solution con from the diethylistilfate is greatly suppressed. tains ethylhydrogen sulfate, sulfuric acid, and Also, reactions2.igreatly limits:the time permitted also diethylsulfate; and tethyl alcohol. The:COn for the hydrolysis of the ethylsulfate and for this"; position approaches equilibrium which varies with . reason it has been proposed that this reaction be the acid strength. Under the conditions, nor 0 carried out' by feeding: the extract to a tower mally used for absorbing .in strong: sul countercurrent to stripping steam, which removes. furic acid}of about:90 to 100:weight percent con the alcohol as fast, as it is formed. However, as centration, the resulting solution will, contain a indicated above, such extract. fed to the tower substantial proportion of, diethyl, sulfate. This must be: Substantially, free of diethyl sclfate in compound. (B.P. 208° C.) issvolatile: with steam, 15 order to keep this volatie: compound outs of the hence is... carried overhead in steam:stripping of alcohol distillate. alcohol; from the partially hydrolyzed extract. It has...also been: found that the hydrolysis of It is an objectionable: impurity in the resulting the diethyl sulfate: in the original acid extract alcohol, aS.it liberates:sulfuric acidiby hydrolysis, can be carried out much more completely than causing corrosion and imparting: a bad odor. to 20 heretofore possible by thes use of two separate the alcohol. Hence, it is: desirable to remove.'di hydrolysis: Zones: prior to the steam stripper and as completely as: possible from the preferably by providing for stream-line:flow. of acid extract before distilling-off the alcohol. This extract through at least the:second of these zones. is normally, attempted by: hydrolysis, but, such Under such conditions a major portion, and pref continuous operations: as:;have: heretofore been 25 erably about .75 to .90% ; of the diethyl sulfate is: described either...involve-incomplete hydrolysis of: hydrolyzed in the first zone, fort which a conven the diethyl Sulfate, or else involve excessive for- - tional mixing: attoclave may be used, and the mation of diethyl ether. For example, when the: final: hydrolysis sis' conditicted in a second stage hydrolysis is conducted by passing:Water, and acid: in which preferably no mixing:of the feed stream extract continuously into a hydrolyzer. With mix 30 with the outlet stream is permitted. This second ing, and withdrawing to a steam stripper: a con stager hydrolysis is spreferably carried out',in a tinuous stream of the -hydrolyzed" material, the tower or pipe: coil of c relatively. Small diameter latter Will always contain sonne-diethyl-sulfate, compared to its length, in order, to prevent by even though a very long. residence time-is-per passing. It', may also be conducted in... vessels mitted in the hydrolyzer. If ther mixer is oper 35 suitably provided with baffles - to divide the re ated batchwise, and a sufficiently long time is action Spacerinto a number of separate zones and permitted to hydrolyze-the-diethyl sulfate.com . to cause the extract to flow progressively through: pletely, very large- equipment is required. In: these. Zonesis with no by-passing from initial to final Zones and vice versa. both operations: the formation of ether is exces 40 The drawing: is a diagrammatic-illustration in sive, as the following reactions occur: partial sectional elevation of one suitable type, of equipment, for carrying out the process of this invention, and indicatess the flow of mate rials. Stitable conditions for there various ab (2) C2H5HSO4--C2H5OH=C2H5OC2H5-H2SO4 : 45 Sorption, hydrolysis and distillation operations: Hence, it has been found desirable to limit the are also given in the following: detailed descrip time during-hydrolysis in which substantial con tion, which is presented for purposer of 'illustra centrations of diethylsulfate and ethyl alcohol tion and not in limitation of this invention. are permitted to be in contact with each other, Referring to the drawing; strong:sulfuric acid in order to avoid reaction 1 50 of about 90-100% concentration, preferably The desired reactions' in hydrolysis of the ex 96-100%, is passed by liner through heater 2. into the upper-portion of an absorption tower 3 at a temperature of about 40 to 50° C. A feed gase containing ethylene such as a Ca fraction of 55 gas-obtained by cracking gas-oil attemperatures Reactions 3 and 1 have been found to be much of about 650 to 760. C. in the presence of steam more rapid than 2 or 4 in .40.55% acid attem and-containing 25 to 50% ethylene, is passed by peratures below about 90°C. In the two-stage lirae 4 into the lower portion of the tower 3 at a 2,474,568 3. 4. pressure of about 400 to 500 pounds per Square drolyzed extract free of diethyl sulfate. Addi inch. The tower contains suitable bubble trayS tional water to further dilute the extract to a or other packing for providing intimate liquid sulfuric acid concentration of about 40 to 45 gas contact and is also provided with Suitable weight percent (hydrocarbon-free basis) may be heat exchangers (not shown) distributed added by line S. This second hydrolysis Zone throughout the tower to remove the heat of re is preferably maintained at a temperature be action and to maintain the temperature in the tween about 80 and 90 or 95° C. With Sufficient tower at about 70 to 85 or 90 C. residence time for the extract therein to permit Under such conditions more than 90% of the substantially complete hydrolysis of the entering ethylene is dissolved in the resulting acid extract 0 diethyl sulfate. This time is Suitably about 20 which contains about 1.3 mols of ethylene per to 30 minutes, depending upon the temperature mol of sulfuric acid, of which about 2% is in the of the vessel and the diethyl sulfate content of forth of diethyl sulfate. This extract is renowed the extract supplied thereto. This time does not from the absorber by line 5 and is passed through require particularly close control because of the cooler 6 and then, at a temperature of about 45° 5 low concentration of diethyl sulfate present. C., into an extract mixer and first hydrolysis The resulting extract, substantially free of di stage , suitably by a number of jets 8 arranged ethyi sulfate and containing ethyl hydrogen Sul on the extract feed pipe in order to provide thor fate and ethyl alcohol, is passed by line 9 to a ough mixing in this hydrolyzer, which is main suitable alcohol generator 28 in which the extract tained at a pressure of about 50 pounds per Square 20 is stripped with steam or other suitable gases for inch gauge and at a temperature of about 80 to distilling off the ethyl alcohol. The generator 29 90° C. also acts as a third hydrolysis Zone in which the The physically dissolved gases which are re hydrolysis of ethyl hydrogen Sulfate is com leased from the extract in this mixer due to the pleted. In order to reduce ether formation, it reduction in pressure are vented from the upper 25 is desirable to remove the alcohol from the extract portion of the vessel through line 9 and are as rapidly as possible, as by stripping the extract washed in the vent gas scrubber With Water in a tower countercurrent to steam. The tower supplied by line , this water then being passed 23 contains suitable packing or distributing plates by line 2 and pump f3 into the vessel in Order for providing intimate liquid-gas contact between to dilute the extract therein. Sufficient Water 30 the down-flowing extract and steam which is Sup is supplied to maintain a Sulfuric acid concen plied to the lower portion of the tower by line 2. tration in this first hydrolyzer of about 40 to 55 The steam-alcohol vapor mixture leaves the top Weight percent (hydrocarbon-free basis). That of the tower through a dephlegmator 22 and then is, the Weight percent of Sulfuric acid is calculated is passed by line 23 into a scrubbing tower 24 in on the basis of the total equivalent weights of which it is scrubbed first with aqueous alkali Sup sulfuric acid and water present in free and com plied by line 25 and then with Water Supplied by bined form, the hydrocarbon content of the ex line 23. The vapors leaving tower 24 are con tract being excluded from this calculation. It is densed in cooler 2 and the resulting dilute alco desirable to obtain rapid and uniform mixing of hol condensate is received in drun 28 from which the extract with the dilution. Water in the vessel 40 it may be concentrated by any suitable method. g; this may be aided by recycling extract by This aqueous alcohol will be found to be free of means of line 4 and pump 5 or by stirrers suit diethyl sulfate and of mineral acid and to con ably disposed in the vessel 7. The recycled ex tain very small amounts of ether. It can be tract may be mixed. With fresh extract in line 5 readily concentrated to provide alcohol of eX or with the dilution water in line 2. A sufficient 45 tremely high purity and good odor. TiOSS of alco residence time is allowed in the Wessel for the hol in the scrubbing water in tower 24 is pre hydrolysis of the major portion of the entering vented by Supplying stripping steam to a lower diethyl sulfate. The resulting diluted and partly stripping section 29 of this tower. - hydrolyzed extract existing in this vessel then The stripped and diluted sulfuric acid leaves has sufficient Solubility for the entering diethyl 50 the bottom of generator 20 by line 30 and may be sulfate that its precipitation as a separate phase concentrated and, if desirable, recycled to the is a yoided. This expedites the hydrolysis reac absorber by any suitable method. For example, tion and reduces the mixing problem. A resi it may be passed into a reboiler 3 in which it dence time in this zone of about 10 to 20 minutes, is heated by “Dowtherm' or other indirect means preferably about 14 to 17 minutes, with temper to a temperature sufficient to concentrate it to atures maintained at 80 to 90° C. (the time being about 65 to 70 weight percent sulfuric acid. This inversely related to the temperature) will be acid may then be further concentrated in a Wac found sufficient to accomplish the desired hydrol uum concentrator and may be recycled to the ab ysis of the diethyl sulfate. This will vary some sorber, with or without such concentration, and What With the concentration of the extract. 60 With Suitable fortification. With fresh Concentrated ihe resulting partly hydrolyzed extract, which acid or oleum. still contains about 4 to 6% of its sulfate com The composition of the sulfuric acid-ethylene ponents in the form of diethyl sulfate, is with extract varies considerably With the operating drawn by line 6 and is passed through a second Conditions Such as acid Strength, temperature, hydrolysis Zone which may suitably be in the 65 degree of contact and ethylene pressure. How form of a long narrow cylinder or tower contain ever, in all Such cases in which there is any sub ing suitably disposed baffles to prevent internal stantial concentration of ethylene in the extract, recirculation and mixing of the streams entering for example, from about 0.5 or 1.0 to 2.0 mols of and leaving this vessel. The second hydrolysis ethylene per mol of sulfuric acid “extract satura Zone may also be in the form of a long pipe or 70 tion,' there is also present diethyl Sulfate in suffi pipe coil Suitably designed to accomplish the same cient amounts so that the two-stage hydrolysis purpose of preventing internal mixing or turbu of the diethyl sulfate, described above, will be lence over more than a limited portion of its found advantageous prior to separation of ethyl length. This avoidance of internal circulation in alcohol from the extract. this ZOne is important in order to obtain a hy 5 The following example is representative of 22,424,568 5 6 extract compositions: obtained in: carrying out 23. Process according to claimi, in which the this invention. With a fresh rich extract prepared ...time of residence: in the first hydrolysis. Zone is with 98% sulfuric acid and containing 1.3 to 1.4 about 14 to 17 minutes. mols of ethylene absorbed per mol of Sulfuric acid. -4. In the preparation of ethyl alcohol by hy The concentration of esters in this extract re 5 'drolysis of ra. Solution containing diethyl sulfate ported as mol percent of total sulfate radical, is and, prepaired by absorbing ethylene in Sulfuric as follows. for a specific example. (A) and for a tacid of.-90-100% strength in a proportion of, to representative range (B): 2 mols of dissolved ethylene per mol of sulfuric acid, an improved method for reducing the 10 amount of diethylsulfate; and ethyl ether in the A. {B resulting ethyl alcohol, comprising passing a Et2SO4------43 mol. percent------(39–47) stream of said solution into a first hydrolysis zone, EtESO4------40 mol. percent------(33-48) adding Water to said zone to dilute the Solution to a 40-55 weight percent (hydrocarbon-free This extract is passed continuously at 80 to 90 basis) sulfuric acid concentration, maintaining C. into a first hydrolysis zone to which water is Said Zone at a temperature of 80-90° C., providing separately added in a continuous stream in the a residence time in said zone sufficient to hydro manner described above in an amount sufficient lyze about 75 to 90% of said diethylsulfate, with to dilute the extract to 45% strength. Sulfuric acid drawing a stream of the partly hydrolyzed solu (hydrocarbon-free basis). The residence time of 20 tion from said Zone and passing it in substantially the extract in this first hydrolysis zone is 16 to i7 Stream-line flow through an elongated Second minutes at 80 C. or about 4 minutes at 90 C. hydrolysis Zone maintained at a temperature of The partly hydrolyzed extract stream leaving this 80 to 90° C., providing a sufficient resident time hydrolyzer has the following composition reported in said second zone for substantially complete as mol percent of total sulfate radical present: 25 hydrolysis of diethyl sulfate, then stripping al cohol from the stream leaving said second Zone Per cent by contact with steam. Et2SO4 ------4 to 6 5. Process according to claim 4, in Which the EthSO4 ------31 to 57 Stream leaving the first hydrolysis zone contains This stream is then passed through a second 30 about 4 to 6% of diethylsulfate based on the total hydrolyzer maintained at 80 to 90° C., without Sulfate content of the solution. internal recirculation, for a residence time of 20 6. Process according to claim 4, in which the to 30 minutes. The exit stream, containing no time of residence in said second hydrolysis zone appreciable diethyl sulfate, but still containing is about 5 to 30 minutes. large amounts of ethylhydrogen Sulfate, is passed 7. An improved continuous process for the to a stripping column where alcohol is removed preparation of ethyl alcohol from a solution con by countercurrent stripping with steam. The re taining diethyi Sulfate and prepared by absorb Sulting alcohol distillate is free of diethyl Sulfate ing ethylene in sulfuric acid of 90-100 weight and contains not more than 5 to 7 volume percent percent concentration in a proportion of 1 to 2 of ethyl ether (based on product alcohol), of 40 mols of ethylene per mol of Sulfuric acid, compris which about 2% is formed in the absorber and ing passing a stream of said solution into a first not more than 5% is formed in the hydrolysis and hydrolysis Zone, separately adding water to said Stripping stages. Zone to maintain therein 40-55 weight percent When operating in the same manner, except (hydrocarbon-free basis) sulfuric acid, maintain that only a single hydrolysis stage is used for 45 ing Said Zone at a temperature of 80-90° C. complete hydrolysis of the diethyl sulfate, the With mixing to provide a substantially uniform formation of ether in the hydrolysis is about 15 composition throughout said zone, providing a Volume percent, based on the product alcohol residence time in said Zone sufficient to hydrolyze obtained. about 75 to 90% of said diethyl sulfate, with 50 drawing a stream of the resulting partly hydro It is to be understood that the Specific exam lyzed solution from said Zone and passing it in ples are presented herein for the purpose of ill Substantially stream-line flow through an elon lustrating suitable methods for carrying out this gated Second hydrolysis zone maintained at a invention and that it is desired to claim this in temperature of 80 to 90° C., providing a residence vention as broadly as the prior art permits. of about 20 to 30 minutes in said second zone for We claim: 55 Substantially complete hydrolysis of diethyl sul 1. An improved process for the preparation of fate, then Stripping alcohol from the stream leav ethyl alcohol from a solution of diethyl sulfate ing Said Second zone by contact with steam. in strong sulfuric acid, comprising diluting said 8. Process according to claim 7, in which the solution with water to a 40-55 weight percent Stream leaving said first hydrolysis zone contains (hydrocarbon-free basis) sulfuric acid concentra 60 tion and hydrolyzing the major portion, but not about 4 to 6% of diethyl sulfate based on the all, of said diethyl sulfate in a first hydrolysis total sulfate content of the solution. Zone maintained at a temperature of 80-90° C., 9. An improved process for the preparation of withdrawing a stream of the resulting partly ethyl alcohol from a solution containing diethyl hydrolyzed solution from said first hydrolysis Sulfate and prepared by absorbing ethylene in zone and passing it through a second hydrolysis concentrated Sulfuric acid comprising passing the zone maintained at a temperature between 80 said solution through a first dilution and hydroly and 95 C., providing sufficient residence time in Sis ZOne in Which the Solution is diluted. With said second ZOne for substantially complete water to about 40-55 weight percent (hydrocar hydrolysis of remaining diethyl sulfate, then 70 bon-free basis) sulfuric acid concentration and stripping alcohol from the stream leaving said in which the temperature and time of residence Second ZOne by contact with steam. are controlled to hydrolyze a major portion, but 2. Process according to claim 1, in which the not all, of Said diethyl Sulfate, then passing the time of residence in said second hydrolysis zone Solution through a Second hydrolysis zone in is about 20 to 30 minutes. 75 which temperature and time of residence are 2,474,568 7 8 controlled to hydrolyze the remainder of said REFERENCES CITED diethyl sulfate until a substantial concentration The following references are of record in the of ethyl hydrogen sulfate is left in said Solution, file of this patent: then passing the Solution to a third hydrolysis and distillation zone in which the hydrolysis of 5 UNITED STATES PATENTS the ethyl hydrogen sulfate is completed and the Number Name Date ethyl alcohol formed is distilled from the diluted 2,013,453 Stuart ------Sept. 3, 1935 acid. 2,045,616 Sargent ------June 30, 1936 LEWIS A. BANNON. 2,096,878 Brooks ------Oct. 26, 1937 CHARLEs E. MORRELL. 2,414,759 Mottern ------Jan. 21, 1947