US2363824A - Process of treating hydrocarbons - Google Patents

Description

Patented Nov. 28, 1944 2,363,824

UNITED STATES PATENT OFFICE,

PROCESS OF rename. n znRocAanoNs I. Louis wWolk, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Application October 26, 1942, Serial No. 463,387

' 17 Claims. (01'. 260-680) This invention relates to a hydrocarbon conversion process and more particularly to a process of catalytically dehydrogenating hydrocarbons specifically paramns or olefins to the corresponding olefins or diolefins.

The principal object of the present invention is to provide an improved process of catalytically dehydrogenating paraflins or olefins. Another object is to provide a catalytic dehydrogenation process wherein the catalyst is a difiiculty reducible metal oxide catalyst and especially bauxite which has been previously treated to spend its olefin isomerizing capacity. Another object is to provide; an improved process, of making isoolefins from the corresponding normal paraflins, and especially isobutene from normal butane. Another object is to provide an improved process of making butene-2 from normal butane. Still another object is to provide an improved process of making butadiene from normal butane. Yet.

another object is to provide an improved procass for preparing both butadiene and isobutene from normal butane. Still another object is to provide an improved process forpreparing butadiene 'and isobutene in proportions suitable for making butyl rubber directly. Another object is to conserve heat in a catalytic dehydrogenation process. Still another object is to provide a processfor simultaneously or sequentially conducting catalytic isomerization of olefins and catalytic dehydrogenation of paraffins or olefins. Numerous other objects will hereinafter appear.

The accompanying drawing portrays diagrammatically one arrangement of" equipment and process steps, all or a suitable portion of which may be utilized for carrying out the present invention. It is to be understood that while the drawing indicates the transfer of catalyst, in practice usually the catalyst itself is not transferred-but the same eiiect is secured by switching the hydrocarbon flow among the several converters in manner known to the art. It will also be obvious that a plurality of converters of the several typ s are ordinarily employed, some of which may be on-stream while the rest are being regenerated.

In carrying out dehydrogenation of hydrocarbons, especially of normal p'araflins and/or normal olefins, over a difiiculty reducible metal oxide dehydrogenating catalyst such as bauxite, the

catalyst possesses under the dehydrogenation conditions marked olefin isomerizing activity andv effects substantial isomerization of the feed olefins, the intermediate olefin '(in the case of dehydrogenation of paramns to dioleflns in a single stage), or the product olefin to isomeric forms which are frequently undesirable and objectionable; For example, in the dehydrogenation of normal butane to normal butene, some isobutene normally appears in the eilluent and this may be undesirable because it contaminates the normal butene sought and requires separation which is expensive. Again, in dehydrogenating normal butane-and/or normal butene l to butadiene some isobutene is formed and is objectionable because it is incapable of dehydro-- genation to butadiene. Likewise in dehydrogenating pure butene-1 or butene-2 to butadiene,

the formation of the other normal butene by isomerization during the dehydrogenation may be objectionable because it interferes with the maintenance of optimum conditions for conversion of either pure butene-1 or butene-2 to butapossesses both isomerizing and dehydrogenating.

catalytic properties under suitable conditions. In accordance with my invention the isomerizing capacity of the bauxite is first neutralized prior to its use as the dehydrogenation catalyst, by employing the bauxite preliminarily as a catalyst for the isomerization of olefins and especially for the isomerization of normal olefins to iso-olefins. In this way the present invention efiects utilization of both the isomerizingand the dehydrogenating properties of the bauxite in an emcient manner and'enables the dehydroenation to be conducted without accompanying undesirable isomerization.

The c'atalyticolefin isomerization may be the simple shifting of the double bond in the olefin, as from either the 1- or z-position to the other, but usually is the conversion of a normal (straight-chain) olefin to a branched-chain olefin, since the latter presents a much more troublesome problem in the dehydrogenation art.

In many cases the dehydrogenation reaction is employed to convert normal parafllns to normal olefins and the olefins for use in the isomerizing step are obtained from this dehydrogenation step, the same catalyst being used first in the 2 isomerization step and then, after being spent or substantially spent therein, being employed in the dehydrogenation step. Preferably the catalyst is transferred from one step to the other, usually by switching the hydrocarbon flow, thus utilizing the residual heat in the catalyst and efiecting substantial thermal economies. Further thermal economies may be effected by passing the efiuent from the dehydrogenation step in heat exchange with cold inlet gases and then into the isomerization step at suitable isomerization temperatures.

While bauxite is highly preferred as the common dehydrogenation and isomerization catalyst for use in accordance with the present invention, I may, though much less preferably, employ other dimculty reducible metal oxide catalysts which are capable of effecting isomerization of olefins and dehydrogenation of par or olefins. Examples are oxides of mrconium, titanium, thorium, vanadium, calcium, strontium, barium, magnesium, beryllium, scandium, yttrium, uranium, tungsten, molybdenum, chromium and aluminum. In other words the oxides of the metals of the left hand columns of Groups II, III, IV, V and VI of the Periodic System, in addition to aluminum oxide, may be used. Bauxite is much preferable to aluminum oxide even in the form of so-called activated alumina." In the case of chromium oxide, it is preferred to employ this oxide supported on a suitable carrier. such as bauxite, activated alumina, dlatomaceous earth, silica gel, etc. The same may be said of molybdenum oxide (M002) and tungsten (W02). In addition to the catalysts enumerated, I may use butene.

any other dificuitly reducible metal oxide cata- I lyst which possesses both dehydrogenating activity and olefin isomerizing power to a substantial extent.

. The broad principle of the invention, outlined above, may be applied specifically in a great many ways with advantage. Among these specific applications are those detailed in the following.

Example i In this embodiment, I may isomerize a l-oleiin to a 2-olefln, e. g. butene-i to butene-2, using bauxite or other dimcultly reducible metal oxide catalyst at temperatures ranging from atmospheric (say F.) to 600 preferably about 350 F. It is preferred to dehydrate the bauxite preliminarily. The method described in copending application of H. E. Brennan, Serial No.

' 450,797, filed July 13, 1942,'may be used for this tained, and the normal isomerizing tendency of the catalyst in the dehydrogenation step is overcome. Moreover, the catalyst carries its residual heat from the first step into the second step thereby conserving heat since the catalyst is not allowed to cool substantially below the isomerization temperature before the hydrocarbon flow is switched to effect the dehydrogenation to butadiene.

The dehydrogenation temperature may be 1100 to 1300 F. The conditions for dehydrogenation to butadiene over diflicultly reducible metal oxide catalysts are now well known to the art and need not be .set forth in detail.

If desired, butene-1 may be dehydrogenated to butadiene in the second step. In this case, as in the case of pure butene-2, optimum conditions for dehydrogenation of this normal butene are employed and the tendency for isomerization to butene-2 in this step is eliminated. Again, instead of a normal butene feed to this dehydrogenation step, I may use a feed of normal butane or of a mixture of normal butane and a normal Under other circumstances I may dehydrogenate normal butane to normal butene only in the dehydrogenation step.

c Example II Step 1.-A i-olefin is catalytically isomerized to "a 2-olefin, for example butene-l to butene-2, as in the first step of Example I, using fresh bauxite as before.

Step 2.The effluent from Step 1, or the hutone-2 content thereof where the efliuent contains significant or objectionable amounts of butene-1, is passed to a dehydrogenation zone where it is dehydrogenated to butadiene over a catalyst which has been used for isomerizing normal butene to isobutehe in Step 3.

Step 3.Normal butene, such as butene-1 or butene-2 or a mixture thereof, but preferably butene-l, is catalytically isomerized 'to isobutene over a catalyst which has been used for isomerizing butene-1 to butene-2 in Step 1 and so'spent for isomerization of butene-l to butene-2. This may be done at temperatures ranging from 700 to 1300 F. The principles of effecting this step over bauxite are disclosed in copending application of Hillyer et 2.1., Serial No. 427,830, filed Jan. 22, 1942. When the isomerization is carried out at temperatures in the dehydrogenation. range, shorter contact times than are used in dehydrogenation are desirable as described in the copending application of Hillyer et a1. referred to. These contact times may be readily determined lay-experiment and may be about 1000 to 1500 or more gas volumes of reactant per volume of catalyst per hour. Isobutene is recovered from the efiluent in the usual way.

The advantages are much the same as for the procedure of Example-I. The catalyst is used thrice, the residual heat of the catalyst irom Step 1 is conserved for Step 3, and the residual heat from Step 3 is likewise conserved for Step 2. Moreover, the tendency of the catalyst to shift the olefin double bond is avoided in Steps 2 and 3 and its tendency to form isobutene in Step 2 similarly is eliminated.

Example III avoid delay. The conditions of contact time in this step difier sufficiently from those in Step 1 to eifect dehydrogenation to butadiene. As before, the isomerizing tendency of the catalyst has b n removed.

Step 2.

,butenes are separated.

Example IV Step 1.Normal parai lins are catalytic'ally dehydrogenated to the'corresponding normal olefins orto mixtures of thecorresponding normal oleflns and dioleflns, as for example, normal butane to normal butene or to normal butene and butadiene, over a bauxite catalyst which has-been used to isomerize norm Step 2.Normal butene. and preferably normal butene derived from the effluen't of'Step 1 is catalytically isomerized to isobutene over fresh bauxite catalyst.

Example V Step 1.-Norma1 paraflins are catalytically deal butene to isobutene in.

hydrogenated tothe corresponding 1-' and 2-ol'efins, for example'normal butane to a mixture of butenes-l and -2, Over bauxite catalyst which has been used for the isomerization of butene-1 to butone-2 in Step 2.

Step 2.--Butene-1 derived from the eflluent of Step 1 is catalytically isomerized to butene-2 over fresh bauxite catalyst.

Example VI Step 1.--Normal butane is dehydrogenated to a mixture of butenes-l and -2 over abauxite which has been used to isomerize butene-1 to isobutene in Step 2. The efliuent is fractionally distilled to separate a bu tion.

Step 2.--The butene-lderived from Step 1 is converted to isobutene over a bauxite catalyst, a

tene-1 fraction and a butene-2 fracportion of which is thereafter used in Step 1 and another portion of which is thereafter performing Step 3.

Step 3.-The butene-2 fraction formed in Step 1 is dehydrogenated to butadiene overa portion of the catalyst which has been used in Step 2.

Example VII Step 1.-Norma1 butane is catalytically dehyused in A 5 to isomerization unit 6 where isome by Sample IX Example vm is duplicated except um than 7 "fluent from Step 2 which contains substantial .amoun'tssof butene-l which is impossible to separate from butadiene and isobutylene by fractional distillationl Accordingly the emuent, or at least the isobutylene, butadiene and, butene-1 content thereof, is passed over fresh bauxite catalyst at 350 F. to convert the butene-1 to butene-2 which is then segregated from the isomerizatio eiiiuent to give a butyl rubber feed. The catalyst pent in this final isomerization step may advantageously be used in Step 1 Example VIII therein. 7

Referring now to the accompanying drawing,

normal butane may be fed to dehydrogenationzone' I where it is deh'ydrogenated to normal butene at temperatures for example of 900 to 1100 F. or to butadiene at temperatures rang-, ing from 1100 to 1300 F. or to mixtures of both at temperatures of from 900 to 1300 F.

The normal buteneeflluent leaves via line 2 whence it may be removed from th system or.

passed via line 3 and thence either via line 4 means of shifting of double bond takes place, or via line 5 to isomerization unit 1 where is oinerization to isobutene occurs.

- Fresh bauxite catalyst may be introduced to,

unit 6 via line 8 and to unit 1 via line IA. The butene-2 derived from the eiiiuent of unit 6 may I beremoved from the system or passed via line 9 and thence either via line ID to serve as feed to unit 1 or via line H to serve as feed to a second a stage dehydrogenation unit I2 wherein normal butene is dehydrogenated to butadiene under drogenated to a mixture of butenes-l and -2 over catalyst which has been used in Step 3. The

Step 2.-The butene-1 formed in. Step 1 is isomerized to butene-2 at 350 F. over fresh baux- Step 3.--The butene-2 derived from either of Step 12 as indicated bylines H and I9;

Steps 1 or 2 is isomerized to isobutene over bauxite which has been used in Step 2. 4

Step 4.The butene-2 not passed to Step 3 is catalytically dehydrogenated to butadiene over catalyst which has been used in Step 3 Example VIIl Step 1-.Normal butene isisomerized to isobutene over bauxite at 700-1300f F. as before.

Step 2.A stream comprising the isobutylene and the normal butene'content of the eiiluent of Step 1, and which stream may consist of the entire eilluent, is fed to a catalytic dehydrogenation zone where the unconverted normal butene vis dehydrogenated to butadiene in such amounts diagrammatically by line 13 and thence lines 14 known conditions.

V The catalyst in Step 6 may thereafter be utilized in either of Steps 1, 7 or '12, as indicated fl5 or IE, respectively. V

The catalyst in Step 7 may thereafter be used" in Step 1; as indicated by lines, l1 and I! or in It will be understood that conventional equipment not shown is employed for recovering the desired components from the eflluents of the several conversion steps. Also provision for recycling' is not shown because obvious to those skilled in the art.

-The'norrnal butene recovered from Step 1 may be in part or in toto directed via lines and 2| to serve as feed to unit l2. Alternatively, where it comprises both butenes-l and -2, it may in part or in toto be passed via line 22 to fractionator 23 where it is separated into butene-1 'as i the overhead via line 24 and butene-2 via line 25. The butene-1 may then be passed via lines 26 and 21 to serve as feed to unit l2, or by lines 28 and l-to unit 6 or by lines 28 and 5 to unit 'I.

The butene-2 leaving via line may be passed via lines 29 and 2|.to ,unit l2. This is a preferred 'feed for making butadiene. Or it may be passed via lines 2|! and 5 to unit I.

If desired, the isobutene-normal butene con- 3 taining eiliuent from unit I may be passed via line 3! through dehydrogenation unit I 2.

eflluent may, pass via'l ine 32 either to fractionation Step 33 where a butyl rubber feed is separated or via line 3| to isomerizationStep 6 whence the eiliuent passes to fractionation Step 35 where the butene-2 is separated to give a butyl rubber feed. If desired the efliuent in line 32 may have been treated in fractionator 36 to r Thev I Iclaim:

i segregate only the butadiene, isobutylene and butene-1 content thereof for charging to unit i.

From the foregoing a great many-advantages of my invention will at once be apparent to those skilled in the art. Among them are the fact that dehydrogenation is accomplished without accompanying isomerization so that optimum conditions are more readily maintained and optimum yields'are obtained. The process is capable of a high degree of flexibilit to yield any desired proportion of products from a given raw material. Heat is utilized in an efllclent manner. If desired separate feeds may be treated in .the individual units; the only connection therebetween being the successive use of catalyst as described. Or the efiluent from one stage may be passed to one of the other stages in the flexible manner described, thereby giving an unusually compact process which is readily adaptable to a wide variety of needs.

produce said iso olefln until said catalyst is spent for olefin isomeriz'ation, and utilizing the spent catalyst from the isomerizing' step as catalyst for the dehydrogenation of the normal paraffin to the a corresponding mono-olefin;

6. In a process for the preparation of isobutene by catalytic dehydrogenation of normal butane to normal butene and catalytic isomerization of said normal butene to isobutene, the steps which comprise contacting said normal butene with bauxite as a catalyst under isomerizing conditions of temperature and pressure to produce said isobutene until said bauxite is'spent for said isomerization, and utilizing the spent catalyst from the isomerizing step as catalyst for the dehydrogenation of said normal butane to said normal butene.

7. The process which comprises catalytically isomerizing normal butene to isobutene with bauxite as a catalyst until said bauxite is spent for said isomerization, and thereafter and in a 2. The process which comprises catalytically isomerizing an olefin by means of a difficultly reducible metal oxide catalyst which when fresh is capable of effecting both isomerization of olefins and dehydrogenation of parafins andolefins until said catalyst is spent for said isomerization, and thereafter in a separate step catalytically dehydrogenating a hydrocarbon selected from the group consisting of parafiins and olefins by means of said catalyst after it has become spent for said isomerization step.

3. The process which comprises catalytically isomerizing a normal olefin to an isoolefin by means of a difiicultly reducible metal oxide catalyst which when fresh is capable of effecting both isomerization of normal olefins to isoolefins and dehydrogenation of paramns and olefins until said catalyst is spent for said isomerization, and

thereafter in a separate step catalytically dehydrogenating a hydrocarbon selected from the group consisting of paraflins and olefins by means of said catalyst spent for said isomerization.

4. The process which comprises catalytically isomerizing an olefin by means of bauxite as a catalyst until said bauxite is spent for olefinisomerization, and thereafter in a separate step catalytically dehydrogenating a hydrocarbon selected from the group consisting of paraflins and olefins by means of said bauxite after it has become spent for said isomerization step.

5. In a process for the preparation of isoolefins by catalytic dehydrogenation of normal paraflins of at least four carbon atoms to the corresponding normal mono-olefins and catalytic isomerization of said normal mono-olefins to the corresponding iso-olefins, the steps which comprise contacting the normal mono-olefin with a diflic'ultly reducible metal oxide catalyst which when fresh is capable of effecting both isomerization of normal olefins to iso-olefins and dehydrogenation of parafiins andolefins under isomeriz-' mg conditions of temperature and pressure to separate step catalytically dehydrog'enating normal butane with said spent bauxite after itv has catalyzed said isomerizing step.

8. A process for' the preparation of butene-2 which comprises dehydrogenating normal butane over a bauxite catalyst to produce a mixture of butenes-l and -2, isomerizing the butene-l contained in said mixture to butene-2 by contact with a bauxite catalyst under isomerizing conditions of temperature and pressure until said catalyst is spent for said isomerization, and utilizing the spent catalyst from the isomerization step as the catalyst for the dehydrogenation of normal butane.

9. A process for the preparation of butadiene and isobutene from normal butane which comprises dehydrogenating normal butane over a bauxite catalyst to produce a butenes-1 and -2 containing mixture, separating said butene-2 from said butene-1, contacting the butene-1 with a bauxite catalyst under isomerizing conditions of temperature and pressure to produce isobutene until said catalyst is spent for said isomerization,

- employing a portion of the spent catalyst therefrom as the catalyst in said dehydrogenation step,

' and contacting the butene-2 with a portion of the spent catalyst from said isomerization step to convert said butene-2 to butadiene.

10. The process which comprises catalytically dehydrogenating' normal butane to normal buteneover a bauxite catalyst, splitting the butene content of the efiluent into at least two portions, catalytically isomerizing one of said butene portions to isobutene over a bauxite catalyst until said catalyst is spent for said isomerization, catalytically dehydrogenating the other of said butene portions to butadiene over a bauxitecatalyst, and utilizing the spent bauxite catalyst from said isomerizing step in at least one of said dehydrogenating steps as the catalyst therefor.

11. The process which comprises catalytically dehydrogenating normal butane .to normal butene over a, bauxite catalyst, catalytically isomerizing butene-1 derived from the dehydrogenation-effluent tobutene-2 over a bauxite catalyst until said catalyst is spent for said isomerization, catalytically isomerizing butene-2 derived from one of the dehydrogenation and isomerization effluents to isobutene over a bauxite catalyst until said catalyst is spent for said isomerization to isobutene, catalytically dehydrogenating butene- 2 derived from one of said dehydrogenation and said first-named isomerization efiiuents to butadiene over a bauxite catalyst, using the catalyst aseasae spent in said first-named isomerization step as the catalyst in saids'econd-named isomerization step, and using the catalyst spent in said second;

named isomerization step as-the catalyst in one of said dehydrogenation steps.

12. The process which comprises catalytically dehydrogenating normal butane to' normal butene over a bauxite catalyst, catalytically isomerizing butene-1 derived from the dehydrogenation efllu-' cut to butene-2 over a bauxite catalyst until said catalyst is spent for said isomerization, catalyti cally isomerizing butene-2 derived from one of the dehydrogenation and isomerization eflluents to isobutene over a bauxite catalyst until said'catalyst is spent for said isomerization to isobutene, catalytically dehydrogenating butene-2 derived from one or said dehydrogenation and said first-named isomerization effluents to butadiene over a bauxite catalyst, using the catalyst spent in said firstnamed isomerization step as thecatalyst in said second-named isomerization step, and using the catalyst spent in said second-named isomerization step as the catalyst in said first-named dehydrogenation step.

13; The process which comprises catalytically isomerizing butene-1 to butene-2 at temperatures ranging from atmospheric to 600 F. over a bauxite catalyst until said catalyst is spent for said isomerization, and thereafter in a separate step catalytically dehydrogenating the butene-2 to butadiene over the bauxite catalyst spent in said isomerizationstep and which has not been allowed to cool substantially below the isomeriza- I tion temperature.

14. The process which comprises catalytically dehydrogenating normal butane to normal. butene over a bauxite catalyst, catalytically isomerizing butene 1 derived from the dehydrogenation efllucut to butene-2 over a bauxite catalyst until said catalyst is spent for said isomerization, catalytically isomerizing butene-2 derived from one or the dehydrogenation and isomerization efiluents, to

isobutene over a bauxite catalyst until said catalyst is spent for said isomerization to isobutene,

' catalytically dehydrogenating butene-2 derived from one of said dehydrogenation andsaid firstnamedisomerization eiliuents to butadiene over a bauxite catalyst, using the catalyst spent in said first-named isomerization step as the catalyst in said second-named isomerization step, and using the catalyst spent in said second-named isomeri 'zation step as the catalystiin said second-named dehydrogenation step.

15. The process which comprises catalytically isomerizing normal butenes to isobutene at tem- 5 peratures ranging from 700 to 1300 F. over a l bauxite catalyst until said catalyst is spent for said isomerization, and thereafter in a separate step dehydrogenating normal butene to butadiene over the bauxite catalyst spent in said isomerization step and which has not been allowed to cool substantially below the isomerization tempera- 16: The process which comprises catalytically isomerizing normal butene over a bauxite catalyst at temperatures from 700 to 1300 F. to convert normal butene to isobutene until said catalyst is spent for said isomerization, and catalytically dehydrogenating a stream derived from the efliuent and comprising the isobutylene and normal bu-.

20 tene content thereof over the bauxite catalyst spent in said isomerization step to convert said normal butene to butadiene and form an eflluent containing isobutylene and butadiene in the relative proportions of at least '70% of isobutylene and not over of butadiene.

- '17. The process which comprises catalytically isomerizing normal butene over a bauxite catalyst at temperatures ranging from 700 to 1300 F. a to convert normal butene to isobutene until said 30 catalyst is spent for said isomerization, catalyti- 40 stream comprising said isobutylene, said buta-l diene and said butene-1 over a bauxite catalyst at temperatures ranging from atmospheric to 600 F. to convert said butene-1 to butene-2 until said catalyst is spent for said isomerization to butene- 2, iractionally. distilling the eflluent from said last-- i named step to separate said isobutylene and butadiene in said proportions free from butene-2, and utilizing the catalyst spent in said second-named isomerization step as the catalyst in said firstnamed isomerization step.

- I; LOUIS WOLK.

cally dehydrogenating a stream derived from the

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