USRE20739E

USRE20739E - Manufacture of ethyl alcohol

Info

Publication number: USRE20739E
Authority: US
Publication date: 1938-05-24

Description

Reissued May 24, 1938 ,IUNITED STATES PATENT OFFICE MANUFACTURE OF ETH'YL ALCOHOL Floyd J. Metzger, New York, N. L. casino:- to Air Reduction Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Original No. 2,050,445, dated Angust 11, 1938, Serial No. 726,071, May 1'1, 1934. Application for reissue March 17, 1938, 8erlal No. 196,574. In the Netherlands June 20, 1932 11 Claims.

sure, with resulting conversion of the ethyleneinto alcohol, which is subsequently condensed along with the excess steam from the escaping I have found that ethyl alcohol can readily be produced in a continuous manner by passing a mixture of ethylene and steam, in suitable proportions, into intimate contact with aqueous phosphoric acid at a regulated high temperature and pressure, with resulting formation of a gascous mixture containing the alcohol together with the excess of ethylene and steam, from which the alcohol and steam can be readily condensed.

This conversion of ethylene into ethyl alcohol can advantageously be carried out in a cyclic manner by maintaining acirculating stream of ethylene under a high pressure, admixing therewith steam in suitable proportions, passing the resulting mixture through or into contact with the aqueous phosphoric acid catalyst at a high temperature, condensing the alcohol and excess steam while maintaining the high pressure, and recycling the ethylene with suitable further additions of ethylene and steam in the further carrying out of the process.

It has been proposed to use phosphoric acid deposited on charcoal as a catalyst for the production oi ethyl alcohol from ethylene and steam at temperaturesbetween 400 and 500 C.; (752 to 932 F.) but the use of such high temperatures is open to serious objection and'diiiiculty. As

I distinguished from the use of such high temperatures, the process of the present invention makes use of aqueous phosphoric acid at far lower temperatures, not materially exceeding about 300 C.; at which aqueous phosphoric acid can exist and be maintained as. such under the conditions of temperature, pressure and ratio 'of steam to ethylene maintained during the carrying out of this process.

(o1. zoo-15c) As compared with sulfuric acid as a -catalyst for the production; of ethyl alcohol from ethylene and steam, phosphoric acid appears to be somewhat less active at lower temperatures, and, in

general, to be more advantageously used at higher temperatures, or temperatures in the higher portion of the, range in which sulfuric acid is effective; and phosphoric acid can alsobe I used in somewhat greater concentration than sulfuric acid without difliculties such as arise from the use of sulfuric acid due to decomposition or reduction and the formation of sulfur dioxide, etc. Phosphoric acid does not appear to have any such oxidizing action as does sulfuric acid.

The phosphoric acid employed in the present process may have a strength, for example, of

from 15 to of phosphoric acid, or somewhat greater strength, provided the phosphoric. acid is maintained as aqueous phosphoric acid in the carrying out of the process. Aqueous phosphoric acid can under proper conditions be used of up to or or higher. Apparently the ethylene combines to some extent with the acid to form an ethyl phosphate so that the catalyst is a mixture of phosphoric acid and an ethyl phosphate.

The strength 0! the aqueous phosphoric acid catalyst is maintained substantially constant at the high temperatures and pressures employed by using regulated proportions of ethylene and steam in the gaseous mixture passed through or into contact, with the acid catalyst.

with the aqueous phosphoric acid catalyst under a high pressure, it is possible to use a much higher temperature without increasing the concentration of the aqueous phosphoric acid, and even with a much more dilute acid, as compared with operations at atmospheric pressure. Using an aqueous phosphoric acid catalyst, without promoters, and with mixtures 01 steam and ethylene, the temperatures are in general in excess of about C. and for bestresults a temperature considerably in excess of- 200 is advantageous, e. g.

around 250 to 300 C. The temperature, however, cannot be varied independently of the other conditions because the temperature, pressure,

acidstrength and ratio of steam and ethylene higher pressures are more advantageous,

- equilibrium strength at higher temperatures;

such as an excess of steam over steam to ethylene,

more dilute acid than obtained from any suitable source,

areinterdepondent. With the same acid strength and the same ratio of steam and ethylene, the temperature can be very,considerably increased by carrying out the process under a high pressure, and the increased temperature mems to have the eflect of greatly increasing the activity or the acid catalyst and promoting the formation of alcohol. 1

The pressures employed in the present process are in general in excess of 100 pounds, and much such as pressures above 200 pounds, and more particularly pressures around 600 pounds or higher. With the higher pressures, for example, around 600 pounds, or 'even' much higher pressures, around 1000 pounds or 2000 pounds pressure, there should be a proper correlation oi the strength of the aqueous phosphoric acid catalyst, the temperature and the proportion oi steam and ethylene. With such high pressures it is possible to use temperatures much higher than it is possible to use at atmospheric pressure with an aqueous phosphoric acid catalyst and at the same time to maintain a much lower strength oi the aqueous phosphoric acid catalyst. The combined use oi a high temperature and pressure with a relatively dilute aqueous phosphoric acid catalyst makes it possible to produce ethyl alcohol in commercial quantities without the obiectionabie decompositionwhich would take place The proportions of steam and ethyleneca be varied, but'in general for the production alcohol free or relatively free from ether, it is advantageous to use a suflicient proportion oi steam, the ethylene, for example, the ratio oi one and one-half parts of steam to one oi'ethylene or of two oi steam to one of ethylene, or even a higher ratio of steam to ethylene. i

. It is possible to produce ether as well as alcohol. where that is desired, by using a lower ratio of steam to ethylene or a stronger acid or a lower pressure: but in generai'the strength of the aqueous phosphoric acid catalyst will depend upon the ratio oi steam to ethylene and the conditions of temperature and pressure employed, and the temperatures are such that, under the pressures and with the proportion of the prosphoric acid is maintained'as aqueous phosphoric acid in the carrying out oi the process. When a constant mixture of steam and ethylene is passed through or in intimate contact with acid catalyst under a high temperature and pressure, the strength of the acid catalyst will reach an equilibrium and will thereafter remain at the the process. i. e. the temperature. pressure and ratio oi steam to-ethylene remain constant; but the equilibrium reached' will represent. a much that which wouldrepresent the equilibrium at the same temperature and 'at atmospheric pressure. and with the same proportion of steam andethylene.

- 'Ihe'ethyle'ne employed in the process may be such as by liquefaction and rectification oi the gases produced from oil or gas'craclrlng operations. Pure or relatively pure ethylene can readily-be produced and when produced or available can be us'edinthe process. Insteadotusing thepure ethylene,- the impure hydrocarbon can be used admixed with other gases-or vapors which vare not objectionable in the proces such as 15amdesired, and passing converter, etc.; and in such case the condensers as the aqueous phosphoric.

as long as the conditions of Where the converter a some rated hydrocarbon vapors, which arenot changed during the process, or other inert gases or vapors.

Where the ethylene employed in the process is impure it will be evident that the extent to which it can be recycled, when the process is carried out with recycling-will be limited by the building up of impurities or of inert gases or vapors or by the formation of undesirable reaction products, in which case the gas after one or more passages through the converter should not be further cycled or should be purified or a constant discharge of the recycling gases should be efiected to maintain the recycling gases of suf- V supplied from any suitable-source, such as a high pressure steam boiler, and admixed with the ethylene in regulated proportions. The mixture of steam andethylene can also beprepared by passing the ethylene through a body of water maintained, ata sufficiently high temperature and under the same pressure employed in the converter. In this case the recirculating ethylene can be passed through such a boiler containing water and the temperature of the boiler maintained to give the proper proportion of steam and ethylene in the gases passing therefrom to the converter.

Instead of carrying out the process in a cyclic manner, by passing the mixture of steam,and ethylene through a single converter, then through i a condenser, and then recirculating the ethylene with admixture of steam under the same high pressure to the same converter, two or more converters can be employed in series with or without condensation of the alcohol and steam from the gases escaping iromadmixing additional steam or ethylene orboth if the gases through the second well as the coverters are advantageously maintained under a high pressure so that condensation aswell as conversion may take place under such pressure.

The use of a series of converters makes possible the maintenance of different strengths ofacid catalyst and of different temperature and pressure conditions in the different converters, thereby making it possible for example to produce' ethyl alcohol free or relatively free from ether in one converter and a mixture of alcohol and ether in another converter where this is de-- sired.

In reierring to catalyst I use the the aqueous phosphoric acid term to include the acid catalyst with whatever other constituents, such as allryl phosphate, it may contain during the catalytic conversion. Provision should be made for insurlng intimate contact of the gases with the acid catalyst, such as the dissemination or distribution of the gases through the acid catalyst. contains a considerable body of acid, the distribution of the gas and the intimate contact of the gas and acid can be promoted by suitable illling material which impedes the upward flow of the gases through the acid. The filling materials should of course be or suitable acid resisting material. Instead oi using a liquid body oi the aqueous phosphoric acid cataly'st. with passage of the gases into intimate contact therewith, the acid may be absorbed .on suitable",-carriers such as pumice stone, silica gel, coke." etc. v

The action of the aqueous phosphoric acid cat alyst can be promoted by the addition thereto the first converter, then sense of certain promoters, or of certain substances which form or become promoters during the carrying out of this process. Silver or silver sulfate may be added in small amount as such a promoter. and the use oi such a promoter enables the process to be carried out at somewhat lower temperatures, or with somewhat increased yields, than when promoters are not present. Lithium sulfate may also be added with beneficial results.

The apparatus employed in carrying out the process includes a converter or converter chamber containing the acid catalyst and provided 1000 or 2000 pounds.

with means such as a filling material distributed throughout the acid, for bringing the mixture of ethylene and steam into intimate contact therewith while maintaining the catalyst and the gases under the necessary pressure and at the necessary high temperature, together with means for supplying the steam and ethylene in suitable proportions and under the necessary high pressure, and-a condenser for condensing the alcohol and admixed steam from the escaping gases. That part oi the apparatus which comes in contact with the acid catalyst should of course be made of suitable acid resistant material, resistant to the action oi the acid catalyst at the high temperatures employed.

Where the process is carried out in a cyclic manner the condenser as well as the converter is maintained under a high pressure and the unconverted ethylene is recycled, additional ethylene admixed therewith, and steam also admixed therewith so that provision is made for supplying both steam and additional ethylene to the cycle under the necessary high pressure. The condenser for condensing the alcohol or alcohol and ether may be a multi-stage condenser, with the separate sections or condensers maintained at progressively lower temperatures so that, for example, the ethyl alcohol is largely condensed in the first condenser in the form of 'a solution oi alcohol in water, and the other is largely separated in a subsequent condenser maintained at a lower temperature. Where ether is formed along with alcohol it is not necessary to condense out the ether, particularly where it is formed only in small amounts, but the ether can be recirculated, along with the ethylene, and again passed through the converter, with maintenance of the condenser at a temperature that will condense the alcohol more or less completely without condensing any considerable amount of ether. The recycled ether will be subjected to the action of the catalyst and. by its presence, may retard the further formation of ether, or may itself be hydrolyzed by the steam and catalystand converted into alcohol.

In general, the stronger aqueous phosphoric acid catalysts will be employed at a lower pres,

sure and temperature and the weaker acid catalyst at a higher temperature and pressure. In general. temperatures between 200 and 300 are advantageous. and pressures between 100 and The nature of the invention will be further 11 lustrated by the following specific examples, but

it will be understood that the invention is not limited thereto.

An aqueous phosphoric acid catalyst is first prepared by absorbing the phosphoric acid on small pieces of coke using, for example, about 10% 01' syrupy phosphoric acid based on the weight 01 the coke. so that the coke acts as a carrier and the aqueous phosphoric acid is absorbed thereby.

'I'hephosphoric acid used initially in making the ly used in the process. since the strength of the acid will adjust itself, during the carrying out of the continuous process. until it is in equilibrium at the temperature. pressure and ratio of steam to ethylene employed, after which it will maintain approximately a constant strength so long as the conditions of temperature, pressure and ratio of steam to ethylene remain approximately constant.

A mixture of steam and ethylene, in regulated and approximately uniform proportions, is passed over such catalyst, above described, for example, at a pressure of about 200 pounds gauge, and at a temperature of the acid catalyst of between 200 and 300 C. Ratios of steam to ethylene as low as one part of steam to seven parts of ethylene can be used, but higher proportions are more advantageous, for example, three parts of steam to seven parts of ethylene, or even higher proportions, for example, around equal proportions of steam and ethylene, or higher ratios. Lower temperatures, around 200 or 225 C., are less advantageous than higher temperatures, such as 250 C. or 275 C.. or 300 0., and the higher temperatures will in general be used with higher be a more dilute acid catalyst, with higher ratios I of steam to ethylene than any given pressure.

Instead of using the aqueous phosphoric acid absorbed on a carrier, as in the above example, the phosphoric acid can be used in a liquid state. for example, at 230 C., or 250' C., or 275 (3., or at 300 C., and at pressures of, for example, 200 pounds per square inch, or 500 pounds per square inch, or higher pressures. The ratio of steam to ethylene may be as low as one part of'steam to four parts oi. ethylene by volume, or one vol ume of steam to two volumes of ethylene, or higher ratios of'steam to ethylene can be used, such as equal proportions of steam and ethylene, or considerably higher ratios. The strength of the phosphoric acid will vary with and is dependent upon the temperature, pressure and ratio of steam to ethylene. In general, with the higher ratios of steam to ethylene, higher tem peratures can be used, and the strength of the aqueous phosphoric acid will be less than that of phosphoric acid at atmospheric pressure at the same temperature.

Instead of using phosphoric acid itself in a liquidstate or supported on a carrier, it can also be advantageously used with the addition of. a promoter, as previously mentioned. Silver sulfate, for example, can be added to the phosphoric acid catalyst in varying amounts, for example, in

with lower ratios at I amount equal to around 6% by weight of the phosphoric acid, figured as 85% phosphoric acid. When such a promoter as silver sulfate is dissolved in the phosphoric acid it will'react therewith to form silver phosphate and sulfuric acid, and it is probable that the sulfuric acid and silver phosphate, as well as any unchanged silver sulfate. all act as promoters in the process.

Such a phosphoric acid catalyst, with added promoter, can be used, for example, at a pressureof 200 pounds, or at higher pressures of around 600 or 1000 pounds, and at temperatures, for example. of around 250 C. or 300 C., and with varying ratios of steam to ethylene, varying from somewhat less than one volume of steam to even higher ratios of steam to ethylene.

In carrying out the process, using the aqueous phosphoric acid catalyst of the foregoing exam- 5, ples, the mixture of steam and ethylene can be prepared in any suitable manner, for example, as previously described. The mixture of gases is forced under regulated pressure in intimate contact with the phosphoric acid catalyst which is maintained at an effective catalytic temperature, and the resulting gaseous mixture, containing the excess of ethylene and steam, together with the ethyl alcohol vapors, and any vapors of ether, if formed, is then passed to a condenser where 1:, the alcohol is condensed as aqueous alcohol, advantageously under the same pressure maintained in the system, and with recirculation of the unconverted eythlene in a manner previously described.

It is one advantage of the present process, when a sufficiently high ratio of steam to ethylene is used, together with an aqueous phosphoric acid catalyst of proper strength maintained at suitably high temperatures and pressures, that it is possible to produce ethyl alcohol without any appreciable production of ethyl ether. With lower ratios of steam to ethylene, and with higher acid strengths, more or less ethyl ether may also beformed along with the ethyl alcohol.

Instead of using phosphoric acid alone as acatalyst, it can advantageously be used in admixture with sulfuric acid as part of a composite catalyst, and either with or without the addition of a promoter such as silver sulfate, etc.

Forexample, a composite catalyst can be used made up of a mixture of phosphoric acid and sulfuric acid in the proportions of about four parts by weight of phosphoric acid to ,two parts by weight of sulfuric acid and with the addition of around 3% or somewhat more of silver sulfate,

- based on the weight of the acid. Such a catalyst can be used, for example, at a pressure of around 200 pounds gauge and at temperatures of the catalyst of around 1'75 to 225 C. or higher and with'varylng ratios of steam to ethylene, varying from somewhat less than equalproportions of steam to ethylene to higher ratios.

Such composite catalysts, containing both phosphoric and sulfuric acid, can be similarly used without the addition of a promoter, using, for example, a composite acid catalyst containing about 35% sulfuric acid, about 30% phosphoric acid and about 35% water, with approximately equal proportions ofsteam and ethylene, at pressures of around 200 pounds or BOO pounds or higher, and with temperatures of around 220 C., or 240 C., or higher temperatures up to 300 C. The strength of the acid above mentioned, that is, the percentage of water which it will contain, will vary with the ratio of steam and ethylene and with the temperature and pressure, but with a constant ratio and with constant temperature and pressure the acid strength will adjust itself until it is in equilibrium and will then remain 35 practically constant solong as the other conditions are maintained constant.

Instead of using approximately equal proportions of phosphoric acid and sulfuric acid, other ratios can be used,.for example, ten parts of phosphoric acid to one part of. sulfuric, and at temperatures between 200 and 300 .C., and pressures of, for example, around 200 pounds or 800 pounds or 1000 pounds or higher: and with varying ratios of steam to ethylene, such as those previously referred to in the preceding examples.

two volumes of ethylene up to equal volumes or.

With both phosphoric acid and sulfuric acid Y employed, either with or without the addition of a promoter, these acids both apparently act, in part at least, through the formation of their ethyl esters, that is, ethyl phosphate'and ethyl 5 sulfate, which are probably formed and bydrolyzed and serve as intermediate compounds or catalysts in the continuous carrying out of the process. When phosphoric acid is used alone, in the form of aqueous phosphoric acid, without 10 the presence of sulfuric acid, the intermediate compound is presumably an ethyl phosphate, while with sulfuric acid alone, in .the absence of phosphoric acid, the intermediate compound is presumably an ethyl sulfate. With both acids 15 present, bothintermediate compounds, or ethyl compounds of both acids,- appear to supplement each other in the process.

Whether the phosphoric acid is used alone, or with an added promoter, or with admixed sulfuric 20 acid, and whether in a liquid state or mounted on a carrier, the strength of the aqueous phosphoric acid, whatever it'may be initially, will adjust itself to the temperature, pressure and ratio of steam to ethylene, and, once the process 25 has been continued until equilibrium is reached. the strength of the acid willv thereafter remain constant or approximately so, and the process can be carried out continuously for long periods of time. 30

This application is in part a continuation of my prior application, Ser. No. 547,452, filed June 2'7, 1931.

I claim:

1. The method of producing ethyl alcohol in a as continuous manner which comprises passing a mixture of ethylene and water vapor in regulated proportions under a high pressure in excess of about pounds per square inch into intimate contact with an aqueous phosphoric acid cata- 4o lyst maintained at an effective and substantially uniform catalytic strength and at a temperature between about C. and about 300 C., and

cooling the resulting gases to condense the alcohol therefrom. 45 2. The method oi producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene. and water vapor in regulated proportions under a high pressure in excess of about 100 pounds per square'inch into intimate 50 co'ntactwith an aqueous phosphoric acid catalyst maintained at an effective and substantially uni- .form catalytic strength and at a temperature between about 250 C. and about 300 C., and cooling the resulting gases to condense the alco- 55 .hol therefrom.

3. Themethod of producing ethylalcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in regulated proportio'nsunder a high pressure in excess of to about 100 pounds per square inch into intimate I contact with an aqueous phosphoric acid catalyst containing a promoter, said, catalyst being maintained at an effective and substantially uniform catalytic strength and temperature within the o5 range of about 200 C. to 300 C., and cooling the resulting gases to condense the alcohol therefrom.

4. Themethod of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform 7n and regulated proportions into intimate contact with a phosphoric acid catalyst mounted on and carried by a suitable support and maintained at an effective and substantially uniform catalytic strength and at a temperature between about 7 V p 20,730 170 C. and about 300 C. and a pressure between about 100 pounds and 2000 pounds, and cooling the resulting gases to condense the alcohol therefrom.

5. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform and regulated proportions into intimate contact with a body of liquid phosphoric acid maintained at an effective and substantially uniform catalytic strength and at a temperature between about 170 C. and about 300 C. and at a pressure between about 100 pounds and 2000 pounds and cooling the resulting gases to condense the alcohol therefrom.

6. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform and regulated proportions into intimate contact with a composite catalyst containing phosphoric acid and sulfuric acid maintained at an effective and substantially uniform catalytic strength and at a temperature between about 170 (land about 300" C. and at a pressure between about 100 pounds and 2000 pounds and cooling the resulting gases to condense the alcohol therefrom.

'7. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in regulated proportions under a high pressure in excess of about 100 pounds per square inch into intimate contact with an aqueous phosphoric acid catalyst maintained at an effective and substantially uniform catalytic strength and at a temperature between about 170 C. and about 300 C.

8. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in regulated proportions under a high Pressure in excess of about 100 pounds per square inch into intimate contact with an aqueous phosphoric acid catalyst maintained at an effective and substantially uniform catalytic strength and at a temperature between about 250 C. and about 300 C.

9. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform and regulated proportions into intimate contact with a phosphoric acid catalyst mounted on and carried by a suitable support and maintained at an effective and substantially uniform catalytic strength and at a temperature between about 170' C. and about 300 C. and a pressure between about 100 pounds and 2000 pounds.

10. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform and regulated proportions into intimate contact with a body of liquid phosphoric acid maintained at an effective and substantially uniform catalytic strength and at a temperature between about 170 C. and about 300 between about 100 pounds and 2000 pounds.

11. The method of producing ethyl alcohol in a continuous manner which comprises passing a mixture of ethylene and water vapor in uniform and regulated proportions into intimate contact with a composite catalyst containing phosphoric acid and sulfuric acid maintained at an effective and substantially uniform catalytic strength-and at a temperature between about 170 C. and about 300 C. and at a pressure between about100 pounds and 2000 pounds.

FLOYD J. MEIZGER.

C. and at a pressure