US2138881A - Hydrogenation - Google Patents

Description

R. PYZEL HYDROGENATI ON Filed May 8, 1937 Dec. 6, 1938.

Wm l1 UNNeNNNR Patented 4Dec. 6,r 1938 i l UNITED STATES .PATENT OFFICE HYDRO GEN ATION Robert Pyzel, Chicago; Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application May 8, 1937, Serial No. 141,527

2 Claims. (Cl. 260-676) This invention relates more particularly to hydrogen and the forced recirculation of the processes involving the direct addition of hydroresidual hydrogen containing gas remaining after gen to unsaturated hydrocarbons in the presence condensation of the completely hydrogenated of catalysts. product.

More specifically it is concerned with a process The process thus comprises generally a coun- 5 which finds applicability in the saturation of tercurrent hydrogenating treatment inl which the mono olenic hydrocarbons boiling within the relative concentration of hydrogen in the final range of gasoline such as, for example, the mono stage is increased by rapid recirculation of olenic liquid polymers produced by the polymer' hydrogen-containing gases and for this reason ization of normally gaseous olefin hydrocarbons the process is specially adapted to the utilization 10 either by thermal or thermal-catalytic methods. of hydrogen-containing gas mixtures of fairly The lower boiling polymers produced from the high hydrogen content rather than the more exnormally gaseous olens are generally of a charpensive pure hydrogen produced by such procacter permitting their direct blending with hyesses as the electrolytic process and processes indrocarbon motor fuels of inferior knock rating, volving the action of mineral acids on metals. To 15 since the mono olens have relatively little tendfurther show the features of the process, the

ency to undergo extensive changes under averattached drawing has been provided which shows lage gasoline storage conditions and this slight the essential parts of a plant in which the process tendency may be readily counteracted by the use may be conducted. The gures are conventional of small quantities of antioxidants or inhibitors. and not drawn to'any'exact or relative scale. 20 Similarly, cracked gasolines which have been The description will be made in connection with freed from their more reactive olenic hydrocarthe hydrogenation of octenes such as those resultbon constituents by light treatment with sulfuric ing from the primary polymerization of butylenes acid or adsorbents such as fullers earth are also to form dimers, though it is to be understood that readily inhibited.. However, the more stringent the principles of the ,process are as applicable to V25 specifications for airplane motor fuels generally other olens or olen-containing hydrocarbon demand a hydrocarbon mixture which is substanmixtures, or unsaturated hydrocarbons generally. tially completely saturated to eliminate all tend- Referring to the drawing, octenes maybe adency to gum formation and deposits in feed lines mitted to the plant through a line I containing and which at the same time has a very high antia valve 2 from a storage not indicated', to a charg- 30 knock value. These requirements' are, met only ing pump 3 which discharges through line 4 conby hydrocarbon mixtures consisting of naphtaining a valve 5 into and through a pre-heating vthenes of limited boiling rangeand the is'oparafelement 6 arranged in a furnace setting 1. The fins, and of the two groups; isoparaflins are prefhydrogen necessary for partially saturating the erable on account of their higher antiknock rathydrocarbons is admitted to line 4. from line 6l 35 ing. The process of the invention to be presently and valve 69, the source of this gas mixture being described is particularly applicable to the comdescribed in connection with the second stage of plete saturation with hydrogen of the dimers prothe hydrogenation. Since the process is not limduced by the polymerization of the butenes to ited to any particular catalyst or conditions of 40 produce mixtures consisting principally `of isotemperature, pressure, and rate of flow inthe two 40 octanes. stages, only general ranges need be given. The A In one specic embodiment the present invenhydrogenation of mono olens as a rule requires' tion comprises the substantially complete hydrolonly moderate temperatures of the order of apgenation of normally liquid olens and particuproximately 3D0-600 F. and moderate pressures larly octenes in two stages wherein the olens of the order of substantially atmospheric to 500 45 undergoing hydrogenation are treated in the first lbs-per square inch. It is preferred in the pres- Sage with quantities 0f hydrogen 0r hydlOgenent instance to maintain substantially vapor containing gas insuilicient to completely saturate phase conditions in the hydrogen-olefin mixture the olens, the supply of gas being that separated passing over the catalysts.

from the product of the second stage and wherein s The preheated mixture of hydrogen and ole-i 50 the partially hydroge'riated olens are contacted iin passes through line 8 containing valve 9 intoI in a second and nal stage with an excess of the upper section I 2 of a reactor l0 which prefhydrogen over that necessary to elec't total saterably consists of multiple parallel tubes of relauratlon, this excess being maintained by the tively small diameter which contain granular A introduction of hydrogen or ,gas mixtures rich in catalyst Il. The mixture of hydrogen and olen 55 passes downwardly through the granular catalyst and enters lower section I3. Since the reactions of hydrogenation are exothermic, cooling is necessary to maintain a constant temperature and provision is made for circulating lcooling uid around the nest of tubes by introducing said fluid through line I4 containing valve I5 and discharging it through line I6 containing valve I1. 'Ihe partially hydrogenated hydrocarbon plus yfixed gases which may consist of unused hydrogen and of methane or any other gases present in the original hydrogen-containing gas mixture pass through a line I8 containing a :valve I9 and through a condenser 20, the condensed liquids and fixed gases then passing through line 2| containing valve 22 to a receiver .23 which has a vent line 24 containing a valve 25 forthe release of the xed gases which are too low in hydrogen to make their re-use worth while. If desired a portion of the partially hydrogenated product may bewithdrawn through line 26 containing valve 21.

The liquid in receiver 23 is now further subjected to hydrogenation in the second stage of f. `the process and is taken through line 28 containing valve 29 by a pump 30 and discharged through line 3| containing a/valve 32 to mix with the fresh and recirculated hydrogen-containing gas; The primary hydrogen supply is introduced through line 33 containing a valve 34 and brought up to the required pressure by means of the compressor 35 which discharges through line 36 containing a valve 31. Recirculated hydrogen from the receiver of the second hydrogenating stage enters line 36 by way of line 6I and the mixture of partially saturated olefin plus an excess of hydrogen is preheated to a proper temperature during passage through a heating coil 38 arranged to receive heat from a furnace 39. The general conditions of operation in the second stage will be broadly the same as those employed in the rst stage though in the case of any given charge they will obviously be modified in consideration of the degree of saturation of the partially saturated material from the primary stage and the excess .of hydrogen which is present. y

The preheated hydrogen and olefin vapors follow line 4Il'containing valve 42I and enter the upper section 44 of reactor 42 which may be of the same general construction as the primary stage reactor I0 and contain granular catalyst 43 in nested tubes, the vproducts of hydrogenation plus excess hydrogen accumulating in lower section 45. Cooling iiuids may be introduced around the reaction tubes through inlet line 46 containing valve 41 andfdischarged through exit line 48 containing valve`49. Y

Unused hydrogen and other xed gases along with vapors of hydrogenated hydrocarbons pass through line 50 containing a valve 5I and through a condenser 52 in which the normally liquid constituents are condensed to flow in admixture with the xed gases through line 534 containing valve 54 to receiver 55, the nal completely hydrogenated product being withdrawn to storage through line 63 containing valve 64.

The xed gas mixture from receiver`55 is vented through a line 56 containing a valve 51 and taken by a compressor 58 to be discharged through a line 59 containing a vaivel 60. At this point the amount of gas recirculated through line 6I and valve 62 to the'final hydrogenating stage is preferably regulated so that there is a considerable excess of hydrogen over that necessary vfor complete saturation -of the partially saturated products from the primary hydrogenating stage. In the operation of the present process the second s'tage of hydrogenation in which the partialy hydrogenated hydrocarbons from the rst stage are naly admixed with hydrogen from outside sources ahd recirculated -hydrogen-containing gases, is preferably operated at a somewhat higher pressure than the flrst stage so that in most instances the pressure in the receiver 55 will be su'icient to causea ow of hydrogen-containing gas to the first stage of the process from line 56 through line 65 and valve 66 and line 61 and valve 69. However, if the rate of recirculation of hydrogen by pump 58 is high, the pressure in line 56 may be reduced to an extent that it cannot be depended upon to insure a regular flow into line 65, in whichevent advantage may be taken of the discharge pressure of the pump and the gas passed to the first stage by way of line 61 and valves 68 and 69 with valve 66 closed. In either event valve 69 may be of the automatic regulator type.

The process thus briefly described above is particularly suited to the employment of what may be termed impure hydrogen as long as there are no substances contained therein which poison the catalysts used, such as hydrogen sulfide, chlorine, etc. Thus it is particularly suited to the utilization of hydrogen produced by cracking heavier hydrocarbons or hydrogen-containing mixtures produced by the interaction in. the presence of catalysts of methane or other light hydrocarbons with steam to produce mixtures of carbon monoxide and hydrogen. It has been shown by experiments that whereas a molecular excess of 2:1 of hydrogen to octenes may be necessary in a single stage catalytic hydrogenation to produce a mixture consisting of 98% octanes, the present process may require as low as only a 10% excess of hydrogen to effect the same degree of saturation. When operating on octenes with fairly active catalysts, such as, for example, reduced nickel on siliceous supports, circulation of the separated gases from the nal stage is maintained at such a rate that with the fresh supply of hydrogen admitted there is present at all times approximately two times as much hydrogen as is necessary to effect the substantially complete saturation of the product from the first stage.

The foregoing specification along with the accompanying numerical data are sufficient to illustrate the commercial value and the nature of the results obtainable by the use of the present process, but neither are intended to unduly limit the scope of the invention.

I claim as my invention:

1. A two-stage hydrogenating process which comprises subjecting unsaturated hydrocarbon material in a rst hydrogenatingstage to hydrogenating conditions in admixture with a limited quantity of hydrogen such as to effect only partial saturation of the hydrocarbon material, supplying the partially saturated material to a second hydrogenating stage, introducing .fresh hydrogen-containing gas to said second stage and there'n completely saturating the hydrocarbon material, separating the saturated material fromv t residual hydrogen-containing gas, supplying to the rst stage such an amount of said residual gas` as -will provide said limited quantity of hy over that required for the complete saturation of the partially saturated hydrocarbon material.

2. A process for converting octenes into octanes which comprises subjecting the octenes in a rst hydrogenating stage to hydrogenating conditions in admixture with a limited quantity of hydrogen such as to eiect only partial saturation of the octenes, supplying the partially saturated octenes to a second hydrogenating stage, introducing fresh hydrogen-containing gas to the second stage and therein completing 'the saturation of the octenes, separating the resultant octanes from 'residual hydrogen-containing gas, supplying to the rst stage such an amount of said residual gas as will provide said limited quantity of hydrogen in the first stage, and recirculating a suf\ cient quantityvof the residual gas to the second stage to maintain therein an excess of hydrogen over that required for vthe complete saturation of the partially saturated octenes.

ROBERT PYZEL.

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