US2249584A - Catalytic treatment of hydrocarbons - Google Patents

Description

July 15,1941.' c. L. THOMAS l CATALYTIC TREATMENT OF HYDROCARBONS Filed Jan. 30, 1939 Patented July l5, 1941 CATALYTIC TREATMENT F nYDnocARBoNs Charles L. Thomas,

versal Oil Products Company, Chicago, corporation of Delaware Chicago, Ill., assignor to *Uni- Ill., a

Application January 30, 1939, Serial No. 253,630 is Claims. (ci. 19e-10)' This invention relates particularly to. the catalytic -treatment of hydrocarbon oils and is more specifically concerned with -a process involving a succession of 'closely cooperating steps for effecting the conversion of hydrocarbon oils into. optimum yields of high antiknock gasoline.

The invention provides for dehydrogenating hydrocarbon oils in the presen-ce of a catalyst to .produce substantial quantities of liquid oleiinic hydrocarbons lfollowed by catalytic cracking of the .resulting liquid products and )polymerization of the normally gaseous olenic hydrocarbons f produced in both the dehydrogenation and the catalytic cracking steps. In addition,'the invention provides for subjecting the residual gases, left after the removal of oleflns in the polymerization'step, to dehydrogenation in commingled state with 4the charging stock in order to dehydrogenate the paramns to olefins andthereby increase the amount of available normally gasevous olefinic hydrocarbonsin the charge to the fpolymerizers.

' It has been found that hydrocarbon oils previously subjected to dehydrogenation respond more readily to catalytic cracking than either parafiinic or aromatic hydrocarbons because in properly controlled dehydrogenation substantial7 quantitles of liquid olefinic hydrocarbons may be produced. Furthermore, it has been found that the catalytic cracking reaction may be carried out at a lower temperature when the charge has been .previously subjected to dehydrogenation and there is less deposition of carbon on the catalyst because of the lower temperatures employed. It is known,'a1so, that in catalytic cracking relatively large yields of normally gaseous olefinic hydrocarbons are produced which, when subjected to polymerization, polymerize to form Aa gasoline of relatively high octane number. Therefore, the main object of this invention is to carry -'4 out the three operations in a combination of steps designed to produce an optimum yield of gasoline of relatively high antiknock value.

Within the broad concepts of this invention dehydrogenation refers to the .breaking of car' ticularly an olei'inic hydrocarbon to form one molecule of a heavier hydrocarbon.

In one specic embodiment the present invention comprises subjecting vaporized hydrocarbon oil to contact with a dehydrogenating catalyst under selected conditions of temperature and pressure in a. primary step, separating xed gases from the dehydrogenated' products, subjecting the liquid dehydrogenated products in the vapor state to contact with a cracking catalyst under selected condi-tions of temperature Yand pressure in a second step, subjecting the conversion products from said second step to separation and fractionation to separate gas, gasoline, andA heavier hydrocarbons,l recovering the gasoline as a product of the process,'subjecting the gas from said second step, together with the gas from said first step, to polymerization inthe third step, separating residual -gases from the product. obtained from said third step, and subjecting said residual gases to dehydrogen'ation in commingled bon-to-hydrogen bonds resulting in the splitting 01T of hydrogen from the'molecule and the formation of a molecule containing a double bond, such as for example, an olefin from a paraffin hydrocarbon. Catalytic cracking refers primarily to the breaking .of the carbon-to-earbon bonds resulting in the formation of two or more molecules of lighter hydrocarbonsthan theoriginal. Polymerization refers to the joining together of two .or more molecules of an unsaturated, and parstate with thezcharging stock in said rst step.

, The outline'of the process given in the preceding paragraph will be amplified in 'the following description to indicate its important features in -greater detail by describing the charac- .teristic operations in connection with the attached diagrammaticdrawing. The drawing illustrat one specific form of :apparatus in which the process of the invention may be conducted. It is' not drawn to any absolute or relative scale and the design and relative sizesof the individual units may be varied within reasonably wide ranges without departing from the broad scope of the invention.

Referring to the drawing, charging stock for the process, preferably comprising a hydrocarbon oil 'heavier' than gasoline, is introduced through line l containing valve 2 to pump 3A which discharges-through line 4 containing valve 5 into heating coil 6. The oil subjected t'o heating in-coil 6 is substantially completely vaporized therein and raised to the desired temperature by means of heatl supplied from a suitable furnace 1. In order to suppress thepyrolytic cracking reaction when vaporizing the chargingstock, it is preferred that relatively short heating times be employed in heating coil 6, relatively low.

superatmospherlc pressures, and relatively high heat input rates. The vap-orzedcharging stock is discharged from heating coil 6 and is directed through line' 8 containing valve 9 to catalytic reactor l0. I 1

Preferably and 4in .the case here illustrated, catalytic reactor I 0 comprises a plurality of small diameter reactor tubes I I connected in parallel between upper and lower headers I2 and I3 and is disposed within a heating or cooling zone I4.

Since'dehydrogenation is an endothermic reaction gases, which may be introduced to zone I4 l through duct I 5, passed in indirect heat exchange relationship with -the vapors passing through reactor tubes II, after which they are discharged from the upper portion of zone Il through duct I6.

In catalytic reactions, such as dehydrogenation, the deposition of carbon on the catalysts is relatively rapid and tends to decrease their activity. In order to obtain best results, relatively short periods of operation are preferably employed, i. e., the catalysts are subjected to contact with process vapors for a relativelyr short time and are then reactivated in approximately the same length of time. In this case -it is preferred that a plurality of reactors be employed, each disposed Within a separate heating or cooling zone, and in order to make vthe operation continuous reactivation may be accomplished in some of the reactors while the others are processing.

Although I have found it advantageous to employ a reactor of the type described above, various other kinds of reactors may be employed, such as, for example, the chamber type, Without departing from the broad scope of the invention. The hydrocarbon vapors introduced to header I2 of reactor I0 are directed through reactor'v tubes II, and are subjected to contact therein with a suitable dehydrogenating catalyst under selected conditions of temperature and pressure. Catalysts are preferably employed which have been found to be highly ecient in the catalytic dehydrogenation of hydrocarbon oil ,vapors to produce optimum yields of oleiinic liquid hydrocarbons. The preferred catalystsy for effecting dehydrogenation are those consisting of activated aluminum oxide supporting about or less of chromium sesquioxide. These catalysts are preferably produced by the preliminary reduction of chromium trioxide left as a residue after the ignition of salt such as adsorbed chromium nitrate, Cr(NOa) s, -or the precipitation of chromium trihydroxide, Cr(OH)3, upon alumina granules. 'I'he process, however, is not limited to this particular composition of dehydrogenating catalysts butmay employ other composite catalysts of av refractory character, such as, for example, alumina or silica or any inert refractory material supporting compounds and preferably oxides selected from the group comprising compounds and oxides of the elements in the left hand column of groups 4, 5, and 6 in the periodic table. The catalysts which are alternately utilizable are not exactly equivalent in their.l reaction and are not to bevconsidered as absolute substitutes one for the other. This fact will be more or less apparent to those conversant with the practical aspects of catalysis.

In the particular case here illustrated, when the catalysts are reactivated the ow of hydrocarbon vapors is stopped and suitable reactivating `gas mixtures at an elevated temperature and containing regulated quantities of oxygen are introduced to catalytic reactor I 0 through line II containing valve I8 and line 3. Re-

the catalysts disposed therein is caused to burn.

The resulting mixture of combustion gases and reactivating gases is discharged from reactor nIII through iline I9 and line 20 containing valve 2I to storage for further use as the reactivating gas mixture, or a portion or all may be cooled and recirculated as the reactivating gas mixture, or the whole may be discharged to the atmosphere as desired. When reactivating, an exothermic reaction takes place and, therefore, suitable means must be employed to dissipate this heat of reaction. In this case, it is preferred to employ cooled combustion gases which are supplied to zone I4 through duct I5, passed in indirect heat exchange relationship with the ow of reactivating gases in the reactor tubes, and are discharged therefrom through duct I6.

The dehydrogenated products are discharged from header I3 of reactor I Il through line I! and are directed through valve 22 to cooler 23 wherein they are'cooled to a temperature sumciently low to substantially arrest the thermal cracking reaction which would otherwise take place, if the products were allowed to remain for a prolonged time under the conditions employed in the catalytic dehydrogenation reaction. Cracking obviously does not take during dehydrogenation because of the relatively short contact times employed. 'I'he co'oled dehydrogenated products are discharged from cooler 23 through 1ine,24 and are directed through valve 25 into separator and absorber 26. The dehydrogenated vproducts introduced to separator and absorber 26 are preferably separated into a fraction substantially free of normally gaseous hydrocarbons and a fraction composed of said normally gaseous hydrocarbons. This may be accomplished by introducing cooled reux condensate produced as subsequently described to the upper portion of separator and absorber 26 through line 96 and by subjecting the bottoms to reboiling. In the particular case here illustrated, reboiler coil 21, to which steam or some suitable heating medium is supplied, is used for reboiling Ain the lower portion of vessel 26; however, various other forms of reboilers may be employed, as is apparent to those skilled in the art, and it is not intended that this invention should be limited to the particular form of apparatus herein described.

Although separator and absorber 26 is preferably operated to remove all of the normally gaseous hydrocarbons, it may be desirable at times to separate only hydrogen and methane, in which case the balance of the normally gaseous hydrocarbons would be commingled with the liquid recovered as bottoms in this step. In any case, the fixed gases separated in separator and absorber 26 are withdrawn from the upper portion thereof through line 28 and are directed through valve 29 to compressor 30 by means of which they are discharged through line 3| containing valve 32 into absorber |05 and treated as subsequently described.v 'I'he liquid hydrocarbons collected in the lower portion of separator and. absorber 26 comprising normally liquid hydrocarbons and.

when desired, condensed and dissolved normally l gaseous'hydrocarbons. are withdrawn from the activating gases pass through reactortubes Il lower portion thereof through line 33 and are directed through valve 34 to pump 35 which discharges through line 36 containing valve 31 to heating coil 38.

I'he dehydrogenated products introduced to heating coil 33 are raised to the. desired reaction temperature, which is preferably high enough to bonate, or ammonium sulfide.

maintain alll of the materials in the vapor'state, by means of heat supplied from a suitable furnace 39. The heated vapors are discharged from heating coil 38 through line 40 and are directed through valve 4| to reactor 42.' Preferably and as illustrated, the design of reactor 42 is similar to reactor I and comprises a plurality of relatively small diameter reactor tubes 43 connected pellets, when desired,'and calcined/at a temperain parallel between upper and lower headers 44 and. 45, respectively, and is disposed within a heating or cooling zone 46. Although catalytic cracking and dehydrogenation diier in many respects, the operating conditions and the means employed for obtainingthese conditions are usually very similar. It follows that the preferred method for heat exchange within reactor zone 46 is by iiuid heating means which may be accomplished by introducing hot. combustion gases through duct 41, passing the sameV in indirect heat exchange relationship with 'the vapors in reactory tubes 43 and discharging the cooler combustion gases through duct 48.

vWhen desired, steam may be introduced to the 1 while the hydrocarbon vapors arejin contactwith charge of catalytic reactor 42 to assist in vaporizing and in reducing the effective pressure on the hydrocarbon vapors. This may be accomplished by introducing steam-to the dehydrogenated products either before their introduction to heating `coil 38 through line 49 containing valve 50 or after they have been vaporized in heating coil 38,y through line 5| containing valve 52, in which case superheated dry steam is preferably employed.

The hydrocarbon vapors introduced to header- 44 of reactor 42 are contacted with a cracking` catalyst disposed within .reactor tubes 43 under selected conditions of temperature and pressure and are discharged therefrom through line 53.

.containing valve 54, preferably cooled byv commingling with the same a suitable cooling medium introduced as subsequently described in order to suppress the thermal cracking reaction,and introduced to separating zone 56 within combined fractionator and separator 551 The preferred catalysts for eifecting catalytic cracking consist in general of pellets or granules of specially prepared silica-alumina masses, the

ratio of the constituents .being varied to suit requirements depending upon the stock to be treat- .ed and the voperating conditions employed. As a rough average, good results are usually obtained, forexample, when employing silica with 15% alumina. This percentage is varied for'best results under specific conditions over- 'a relatively 'wide range, for example, from 2% to 50%, or

alumina may be employed as the major constitu- Aent and silica as the minor constituent, the

amount of silica composited with the alumina being varied over substantially the same range, that is, 2% to 50%. Catalysts of this character may be initially prepared in any of several different manners and subsequently dried. The preferred catalyst is prepared by precipitating silica from a solution of sodium silicate by acidifying vwith acid, such as, for example, hydrochloric acid, subsequently treating and washing the silica to ,remove substantially all of the alkalimetal-ions, suspending the purified silica gel in av solution of aluminum salts, and depositing the alumina upon the suspended silica by the addition of volatile basic precipitants, such as, for

example, ammonium hydroxide, ammonium'car- After the alumina has been deposited upon the puriiiedhydrated silica gel the material is dried, formed into ture of from approximately 850 t'c"'1`000 F. The process, however. Ais not limited to this particular composition of cracking catalysts but'may employ other composite catalysts of a refractory character, such as, for example, silica with ,com-

pounds of the group comprising zirconia, vanadia, alumina-zirconia, alumina-thoria, and other catalysts, such as acid treated clays may be employed. The catalysts referred to above are not exactly equivalentin their reaction and are not to be considered as absolute substitutes one for the other, whichfact will be more or less appar- A' ent to those conversant with the practical aspect of catalysis. A

In catalytic cracking, as in dehydrogenation,

lated quantities of oxygen is introducedto cata- I lytic reactor 42 through line |63 containing valve |64 and line 40. The carbon deposited upon the catalysts disposed within reactor tubes 43 iscaused to burn by .oxidation with air introduced with the reactivating gas mixture. lThe result ing gases are discharged from reactor 42 through line 53 and are directed through line |65 containing valve |66 to (storage or recirculated or discharged to the atmosphere as desired. In order to dissipate the heat evolved during the reactivation, suitable cooling means, preferably comprising cooled combustion gases, are introduced through duct 41., Vpassed in indirect heat exchange relationship with the flow of reactivating gases in the reactor tubes 43 and are discharged therefrom through duct 48. l

Preferably and as illustrated in the .accompanying drawing, vessel 55 comprises a separating zone 56 in its lower portion and a fractionatin gzone 51 separated from said separating .zone

vby means of reflux trapout tray 58. However, other means may be employed to accomplish the i same purpose, such as. for example, separate vessels.

The commingled materials in line 53 are subjected to separation inseparating zone 56 wherein the residualliquids are separated from thevaporous components. The residual liquids are discharged from the lower portion of zone ,56 through line '59 and aredirected through valve 60 to cooling and storage or elsewhere as desired. The vaporous components are introduced to fractionating zone 51 in combined separator and Ifractionator 55 wherein fractionated vapors in the gasoline boiling range are-separated from higher boiling hydrocarbons.4`

Fractionated vapors of the desired endl boiling point are withdrawn from the upper portion of fractionating zone 51 through line 6| and are directed through valve 62 to cooler'and condenser 63. The resulting gas-containing distillate, together with undissolved and uncondensed gases discharged from condenser 63,- are directed4 through line 64 and valve 65 to receiver 66. Un-

dissolved and uncondensed gases collected and separated in receiver 66 are withdrawn from the upper portion thereof through line 61 and are dlrected through valve 68 to pump 69 which discharges through line 10 containing valve 1| into line 3| by means of which they are introduced into absorber in commingled state with the gases removed from the upper portion of separator and absorber, 26. Water collectedin the lower portion of receiver 66, resulting from condensing the steam employed in the process, is withdrawn therefrom through line 11 containing valve 18. Regulated portions of the distillate collected in receiver 66 are directed through line 12 containing valve 13 to pump 14 from whichv comprising a fraction whose average boiling pointis above that of said fractionated vapors, are condensed as reflux condensate therein and co1- lected on trapout tray 58. The reflux condensate is withdrawn from fractionating zone `51. through line 85 and is directed through valve 86 to pump 81. Pump 81 discharges through line 88 and a portion orall of said reflux condensate may be directed through valve 89 to cooling and storage or elsewhere as desired. the reux condensate in line 88 is directed through line 90 and a portion commingled with the conversion products in line 53 for use as cooling oil, 'as previously described, this being accomplished by directing the reflux condensate in line 90 through line 9| containingvalve 92. The remainder of the 'reux condensate in line 90 is preferablydirected through line 93 containing valve 94 to sub-cooler 95 wherein the reflux condensate is cooled to the desired temperature by means of a suitable cooling medium introduced to a cooling coil |69 in sub-cooler 95. The cooled reilux condensate is discharged from Preferably, however,

|68 to cooling and storage or elsewhere as dey sired.

'Ihe gases liberated from the distillate in stabilizer 84 are directed from the upper portion thereof through line |03 containing valve |04 and introduced to absorber |05 by way of line 3| in Vcomnlingled state with the gases from separator and absorber 26 and the gases liberated in receiver 66.

The function of absorber |05 is to recover desirable high boiling components, including substantially al1 of the readily polymerizable oleflns, such as butenes and propenes, from the gaseous products suppliedto 'this zone by adsorption of said high boiling componentsby a suitable absorption medium. In the particular case here illustrated, the absorber oil is introduced to the -i upper portion of absorber |05 by way of line sub-cooler 95 through line 96 containing valve sorber 26 to act as an absorption medium, as

previously described. O'n the other hand, instead of introducing redux condensate to conversion in the second step as an absorption oil, all or a portion of the reflux condensate subjected to conversion in the second step may be introduced to heating coil 38 by way of line 90, line 98, valve 99, and line 36. rA portion of the redux condensate in line 90 may, when desired, be directed through valve |00 for subsequent treatment in commingled state with the hydrocarbon oil introduced to heating coil l6.

Provision is made, in the case here illustrated for removing dissolved gases over those required to produce a distillate of the desired vapor pressure by liberating the same from the distillate in stabilizer 84. Provision is made for rebolling the distillate in the lower portion of stabilizer 84 by passing a suitable heating medium through close coil |0| and provision is made for cooling 4 the upper portion of the stabilizer by passing a suitable cooling medium through closed coil |02. 'I'he stabilized distillate -collected in the lower portion of stabilizer 84 is removed therefrom through line |61 and is directed through valve |22 and passes downward through absorber |05 countercurrent to the ascending gaseswith which it is intimately contacted by suitable means, such as bubble trays, or the like, not illustrated. The resulting enriched absorber oil collects in the lower portion of absorber |05 and the unabsorbed gases are released from the upper portion of the absorber through line |06 and valve |01. The enriched absorber oil is Withdrawn from 'the lower portion of absorber 05 through line |08 and is directed through valve |09 to pump ||0 which discharges through line containing valve |2 into stripper ||3.

Provision is made in stripper` ||3 for stripping the enriched absorber'oil of the dissolved normally gaseous hydrocarbons, and this may -be accomplished by reboiling the distillate collected in the lower portion of stripper ||3 by means of a suitable closed heating coil ||4 to which steam or some suitable heating medium is supplied. The stripped. absorber oil is Withdrawn from the lower .portion of stripper ||3 through line ||5 and is directed through valve ||6 to pump ||1 which discharges through line I8 containing valve ||9 into line |20 by means of which it is introduced to subcooler I2 The cooled absorber oil is discharged from sub-cooler 2| through line |22 containing valve |23 into the upper portion of absorber |05, as previously described. Additional absorber oil, required as makeup in absorber |05, may be introduced from an outside source through valve |24 in line |20.

The stripped gases liberated in stripper ||3 are withdrawn from the upper .portion thereof through line |25 and are directed through valve |26 to compressor |21 which discharges througl line |28 containing valve |29 into and througl heating coil |30. The charge in passing througl heating coil |30 is raised to the optimum temperature for initiating the polymerization of the olens by means of heat supplied from a suitablefurnace |3|.

The heated charge is discharged from heatingl coil |30 into line |32 and ,is directed through valve |33 into a suitable reactor |34 containing polymerizing catalysts. Among preferred cata-- lysts are precalcined mixtures of phosphoric acids and absorbents, the latter preferably being of a vsiliceous character and comprising such materials as certain clays of the montmorillonite and bentonite type, (either raw or acid treated), kieselguhr, precipitated silica, .and other siliceous and refractory materials. Granular catalysts' maybe prepared by making a paste, for example, of kleselguhr and a major portion by Weight of ortho or pyrophosphoric acid, calcining the mix? ture at temperatures of from 570'toi'150" F. to produce a cake, grinding and sizing the cake to produce particles of a convenient size, usually from 4 'to 20 mesh, and, if necessary, subjecting the sized particles to the action of superheated steam at about 110 F. and atmospheric pressure to bring the active catalytic acid tothe state of hydration corresponding to maximum eiciency. The above procedure may be modified by extruding and forming the' original pasty material and calcining the preformed particles.

The reaction of polymerization of oleflns is exothermic, and in 'order to secure best results, means must be provided for extracting evolved f heat to prevent excessive temperature rise in the catalyst zone. The polymerizing catalyst is preferably contained in banks of tubes .of relatively small diameter which are surrounded by a cooling medium, (such as evaporating water) in suitably `'constructed reactors, such as that shown under |34 in the diagrammatic drawing. Preferably and as shown in the accompanying diagrammatic drawing, water is introduced to reactor |34 through line |35 and valve |36, and the steam produced within the reactor is withdrawn f rom the upper portion thereof through line |31 and valve |38. y

Although only one reactor is shown in the accompanying diagrammatic drawing, a plurality of reactors connected in series, may be employed4 to obtain the desired contact time, and otherwise connected so that individual reactors may be segregated when the catalyst has become spent in order to replace such spent` catalyst while employing other reactors in which the catalyst has suilicient activity to maintain operation.

The reaction products from reactor |34, comprising polymers and residual gases, are withdrawn from the lower portion thereof and directed through line |39 containing valve |40 to stabilizer |4|. Provision is made in stabilizer |4| for removing residual gases over and above the amount required for obtaining the desired vapor pressure on the polymer product. Provision is made for reboiling the distillate contained in the lower portion of stabilizer |4| by means of a suitableclosed heating coil |42 to which steam of some suitable heating medium is supplied. The stabilized distillate of the desired vapor pressure is withdrawn from the lower portion of stabilizer |6| through line |43 and. is directed through valve |44 to cooling and storage or further treatment, not'shown.

Residual gases liberated instabilizer itl .are withdrawn from rthe upper portion xthereof through line |45 and are directed through valve lated amounts of gaseous hydrocarbons with'-v drawn from reiiuxaccumulator |50 may be directed through line |61 containing valve |62 to t storage or to the atmosphere as desired.

" The preferred range oi operating conditions which may be employed in an apparatus such as illustrated and. above described to accomplish the desired results is approximately as follows:

The primary heater to which the charging stock is supplied may employ an outlet temperature ranging, for example, from 800 to 1200 F. and a superatmospheric pressure of from 20 to l00 pounds or more per square inch. Substantiallv the same conditions of temperature and pressure are maintained on the process vapors introduced to tne catalytic dehydrogenation reactor as are employed on the outlet of the heating coil to which the charging stock is supplied. The separator and absorber may employ a superatmospheric pressure substantially -.the same as that on the outlet of the catalytic dehydrogenation reactor. The iurnace to which the dehydrogenated products are introduced may employ an outlet temperature ranging. for exam-4 ple, from 800 to 1200" F. and a superatmospheric pressure of from 20 to 100 pounds or more per square inch. However, this process permits the lutilization of lower temperatures than would otherwise be employed if the cracking step was not preceded by the dehydrogenation step. Substantially the same conditions of temperature and pressure may be employed inthe catalytic cracking reactor as are employed on the outlet of the heating coil to which the dehydrogenated products are supplied., The conversion products discharged from the catalytic cracking reactor are preferably cooled to a .temperature ranging,

for example, from 600 to 800 F. or at least to a temperature sufciently low to substantially arrest any thermal cracking reaction. The cornbined fractionator and separator may utilize a pressure substantially the same as that employed at the outlet of the catalytic cracking reactor. The stabilizer, absorber, and stripper may utilize a superatmospheric pressure ranging, for example,from 50 to 200 pounds or more per square inch. The heating coil and communicating polymerizing reactor to which the normally gaseous hydrocarbons are introduced may employ a temperature ranging, for example, from 240 to 420 F. and a superatmospheric pressure in theapproximate range of 200 to 500 pounds or more per |46 to condenser |41. Light distillate, comprising liqueiied normally gaseous hydrocarbons, together with undissolved and uncondensed gases,v is dlschargedfrom condenser |41 through line square inch. The stabilizer .to which the polymerization reaction products are supplied may employ a superatmospheric pressure ranging, for example, from 100 to 250 pounds or more per square inch.

As an example of one specic operation of the 1 processas it may be accomplished in an appa- |58 and 'is directed through valve |49 'to reux accumulator |50. Reflux accumulated in reilux accumulator |50 is withdrawn from the lower Cportion thereof through line` |5| and is directed through valve |52 to pump |53 which discharges 'through line |54 containing valve |55 into the upper portion of stabilizer |4| for cooling and reuxing therein. The gaseous hydrocarbons col-- vlected in reilux accumulator |50 are directed y through linev |58 and valve |51 to compressor |58 which discharges through line |59 containing valve |60 into line 90 by means of which the 'gaseous hydrocarbons are introduced to line 4- wherein they are commingled with the charging stock prior to heating coil 6. When desired, reguratus such as illustrated and above described is approximately as follows:

Charging stock comprising a 36.7 A. P. I.

gravity'Midcontlnent gas-oil was subjected to contact in the vaporstate with an aluminachromia dehydrogenating catalyst at a. temperature -of approximately v932" F. and under a super- Y atmospheric pressure of approximately 40 pounds per square inch. The Adehydrogenated products were treated for the removal of xed gases and the resulting'dehydrogenated products subjected..

to contact in the vapor state with a silicaalumina catalyst at a temperature of approximately 900 F. and under a superatmospheric pressure of approximately 30 pounds per square inch. The conversion products were cooled to aplproximately 650 F. by commingling reflux condensate produced as hereinafter described with the same. The conversion products, together with the cooling oil, were subjected to separation for the removal of liquid residue and the vaporous materials subjected to fractionation .to separate fractionated vapors of the desired end boiling point from the heavier hydrocarbons. The fractionated vapors, including normally gaseous hydrocarbons, were subjected to condensation and the resulting distillate and undissolved and uncondensed gases collected and separated in a receiver. The heavier: hydrocarbons were condensed as reflux condensate in the fractionating zone and a portion utilized as cooling oil to the conversion products discharged from the catalytic cracking step and the balance employed as an absorption oil to the gas separation step following the dehydrogenation reaction. Gasoline was subjected to stabilization to remove a portion of the normally gaseous hydrocarbons in order to reduce the vapor pressure of the gasoline product. The normally gaseous hydrocarbons obtained from the stabilization step, together with the receiver gases and the fixed gases removed inv the separator and absorber following the dehydrogenation step, were subjected to absorption for the removal of hydrogen and methane. Normally gaseous hydrocarbons were recovered from the stripper substantially free from hydrogen and methane and were subjected ,to polymerization in the presence of a solid phosphoric acid polymerizing catalyst at a temperature of approximately 450 F. and under a pressure of approximately 300 pounds per square inch. The polymerized products Were subjected to stabilization and the gaseous hydrocarbons recovered therefrom, comprising substantially paraffinic hydrocarbons were subjected to dehydrogenation in commingled state with .the hydrocarbon oil charging stock. This operation yielded approximately 82% of 81 octane number gasoline by volume of the charge, the balance being attributed normally to gas and loss,'and a minor yield of approximately 4% liquid residue.

I claim as my invention:

1. A lprocess for producing gasoline of high anti-knock value from hydrocarbon oils heavier than gasoline, which comprises vaporizing the hydrocarbon oil charging stock, subjecting the vapors to contact with aA dehydrogenating catalyst under dehydrogenating .conditions of temperature and pressure in a primary step, separating xed gases from the dehydrogenated products, subjecting the dehydrogenated liquid -products in the vapor state and under cracking conditions of temperature and pressure to contact with a cracking catalyst in a second step, separately recovering gas, gasoline, and heavierF hydrocarbons from the conversion products produced in said second step, removing said gasoline as a product of the process, subjecting said 2. A process lfor producing gasoline of high antiknock value from hydrocarbonoils heavier than-gasoline, whichy comprises vaporizing the hydrocarbon oil charging stock, subjecting the vapors to contact with a dehydrogenating catalyst consisting essentially of an inert refractory material supporting a compound selected from the group consisting of compounds of the elements in the left hand columns of groups 4, 5, and 6 of the periodic table under dehydrogenating conditions of temperature and pressure in a primary step, separating xed gases from the dehydrogenated products, subjecting the dehydrogenated liquid products in the vapor state and under cracking conditions of temperature and pressure to contact with a cracking catalyst in a second step, separately recovering gas, gasoline, and heavier hydrocarbons from the conversion products produced in said second step, removing said gasoline as a product of the process, sub- Y jecting said heavier hydrocarbons to substantial further conversion byA returning them in part to said first step and in part to said second step, subjecting said xed gases together with the gases produced in said second step to contact with a polymerizing catalyst under conditions selected heavier hydrocarbons to substantial further coning catalyst under conditions 4selected to effect substantially complete polymerization of the olens. in a third step, separating residual gases from the polymer gasoline produced in said third step and recovering the latter as a product of the process, and subjecting said residual gases to dehy- Adrogenation in Ycommingled state with the charging stock.

v the process, and subjecting said residual gases to to effect substantially complete polymerization of the olens in a third step, separating residual gases from the polymer gasoline produced in said third step and recovering the latter as a product of the process, and subjecting said residual gases to dehydrogenation in commingled state with the charging stock. L

3. A process for producing gasoline of high antiknockv value from hydrocarbon oils heavier than gasoline, which comprises vaporizing the hydrocarbon oil charging stock, subjecting the vapors to contact with a dehydrogenating catalyst consisting essentially of an inert refractory material supporting a compound selected from the group consisting of compounds of the elements in the left hand columns of groups 4,A 5, and 6 in the-periodic table under dehydrogenalting conditions of temerature and pressure in a primary step, separating fixed gases from the dehydrogenated products, subjecting the dehydrogenated liquid products in the vapor state and under cracking conditions of temperature and pressure to contact with a cracking catalyst consisting essentially of silica and a member of the group consisting of alumina, zirconia, vanadia. alumina-zirconia, and alumina-thoria in asecond step, separately recovering gas,'gasoline, and heavier hydrocarbons from the conversion products produced in said second step, removing said gasoline as a product of the process, subjecting said heavier hydrocarbons to substantial further conversion by returning them in part to said first step and in part to' said lsecond step, subjecting said fixed gases, together with the gases produced insaid second step, to contact with a polymerizlng catalyst under conditions selected to effect substantially complete polymerization of the olefins in a third step, separating residual gases l from the polymer gasoline produced in said third step and recovering the latter as a product of dehydrogenationin commingled state with the charging stock. I

4,. A processv for vproducing gasoline of high antiknock value from hydrocarbon oils heavier than gasoline, which comprises vaporizing the hydrocarbon oil charging stock, subjecting the vapors to contact with a dehydrogenating catastate with the charging stock.

` 800 to 1200 F. and under a llyst consisting essentially of an inert refractory material supporting a compound selected from the group consisting of compounds of the elements in the left hand columns of groups 4, v5, and 6 in the periodic table under dehydrogenating conditions of temperature and pressure in a primary step, separating -xed gases from the dehydrogenated products, subjecting the dehytial further conversion by returning them in part to said first step and in part to said second step, subjecting said fixed gases, together with the gases produced in said second step, to polymerization in the presence of a phosphoric acidcontaining catalyst under conditions selected to effect substantially complete polymerization of the olens in a third step, separating residual gases from the polymer gasoline produced in said third step and recovering the latter as a product of the process, and subjecting said residual gases to dehydrogenation in commingled 5. A process for` producing gasoline of high anti-knock value from hydrocarbon oils heavier than gasoline, which comprises vaporizing the hydrocarbon oil charging stock, subjecting the vapors to contact with an alumina-chromia dehydrogenating catalyst at a temperature of from pressure of from substantially atmospheric to 100 pounds per square inchA in a primary step, separating xed gases from the dehydrogenated and under a pressure of from substantially atmospheric to 100 products, subjecting the' dehydrogenated liquid products in the vaporstate and at a temperature of from 800 to 1200 'E'.

pounds per square inch to contact with a silica-alumina cracking catalyst in a second step, separately recovering gas, gasoline,

and heavier hydrocarbons from the conversion products produced in said second step, removing said gasoline as a product of the process, sub` jecting said heavier hydrocarbons to substantial further conversion by returning them in part to said first step and in part to said second step,

subjecting said fixed gases, together with the gases produced in said vsecond step to polymerization in the presence of a phosphoric acid-containing catalyst at a temperature of from 250` to 450 F. and at a superatmospheric pressure of 'from 100 to 500 pqunds per lsquare'inch in a third step, separating residual gases from the polymer` gasoline produced in said third step and recovering thelatter as a product of the process,

and subjecting said residual gases to dehydro-4 genation in commingled state with the charging stock. f

6. A process for producing gasoline of high lanti-knock value from hydrocarbon oils heavier than gasoline, which comprises vaporizing said hydrocarbon oil, subjecting the resulting vapors to contact with a dehydrogenating catalyst under dehydrogenating conditions of temperature and pressure ina primary step,

cooling the dehydrogenated products, introducing the cooled de- Vhydrogenated products to a separator and abv said residual gases sorber wherein fixed gases are removed from the dehydrogenated4 liquid products, vaporizing said dehydrogenated liquid products, subjecting the vaporized dehydrogenated liquid products to contact with a cracking catalyst under cracking conditions of temperature and pressure in a second step, cooling the conversion products with reux condensate produced as hereinafter set forth, introducing said conversion products, together with the cooling oil, to a separating zone wherein liquid residue is separated from the vaporous components, removing and recovering said liquid residue as a product of the process, subjecting said vaporous components to fractionation to separate fractionated vapors of the desired end boiling point from heavier hydrocarbons whose average boiling point is above that of said fractionated vapors, condensing said heavier hydrocarbons as reflux condensate in the in part to said conversion products, condensing and recovering said fractionatedvapors to form distillate and gas, separating normally gaseous hydrocarbons in excess of those required to make the desired vapor pressure from the distillate, recovering the stabilized distillate as a product of the process, subjecting said gases, together with said xed gases produced in said primary step, der polymerizing conditionsof temperature and pressure in a third step, separating -residual gases from 'the polymer product, and returning for conversion in commingled state with said hydrocarbon oil charging stock.

'7. A process for producing gasoline of high antiknock value from-hydrocarbon oils heavier than gasoline, which comprises vaporizing said hydrocarbon oil, subjecting the resulting vapors to contact with a dehydrogenating catalyst consisting essentially of an inert refractory material vsupporting a compound selected from the group consisting of compounds of the elements in the left hand columns of groups 4, 5, and 6 in the periodic table under .dehydrogenating conditions of temperature and pressure in at primary step, cooling .the dehydrogenated products, introducing the cooled dehydrogenated products to a separator and absorber wherein fixed gases are removed from the dehydrogenated liquid products, vaporizing said hydrogenated liquid products, subjecting the vaporized dehydrogenated liquid products to contact with a cracking catalyst under cracking conditions of temperature 'and pressure' in a second step, cooling the conversion products with reflux condensate produced as hereinafter set forth, introducing said conversionproducts, to-

gether with the cooling oil, to a separating zone wherein liquid residue is separated from the va. porous components, liquid-residue as a product of the process, subjecting said vaporous components to fractionation to separate fractionated vapors of the desired end boiling point from heavier hydrocarbons whose average boiling point is above that of said fractionated vapors, condensing said heavier hydrocarbonsas reflux condensate inthe fractionating zone-and introducing it in part to said separator and absorber as absorber oil and in part to said conversion products, condensing and recovering said fractionated vapors to form distillate and gas, separating-normally gaseous hydrocarbons in excess of those required to make from the distillate,

the desired vapor pressure to contact with a polymerizing catalyst unto the dehydrogenation step removing and recovering said recovering the stabilized distillateas a product lof the process, subjecting said gases, together with said .xed gases produced ln said primary step, to contact with a polymerizing catalyst under polymerizing conditions of temperature and pressure in a third step, separating residual gases from the polymer product, and returning said residual gases to the dehydrogenation step for conversion in commingled state with said hydrocarbon oil charging stock.

8. A process for producing gasoline of high `antiknock value from hydrocarbon oils heavier from the dehydrogenated liquid products, vapor-- izing said dehydrogenated liquid products, subjecting the dehydrogenated liquid products in *A the vapor state land under cracking conditions of temperature 'and pressure to contact witha cracking catalyst consisting essentially of silica with a member of the group consisting of alumina, zirconia, vanadia, alumina-zirconia, and alumina-thoria in a second step, cooling the conversion products with reflux condensate produced as hereinafter set forth, introducing said conversion products, together with the cooling oil, to a separating zone wherein liquid residue is separated from the vaporous components, re-

moving and recovering said liquid residue as a product of the process, subjecting said vaporous components to fractionation to separate fracy tionated vapors of the desired end boiling point from heavier hydrocarbons whose average boiling point is above that of said fractionated vapors, condensing said heavier hydrocarbons as reflux condensate in the fractionating zone and introducing it in part to said separator and absorber as absorber oil and in part as cooling to said conversion products, condensing and recovering said fractionated vapors to form distillate and gas, separating normally gaseous hydrocar-v bons in excess of those required to make the desired vapor pressure from the distillate, recovering vthe stabilized distillate as a product of the process, subjecting said gases, together with said fixed gases produced in said primary step, Vto contact with a polymerizing catalyst under polymerizing conditions of temperature and pressure in a third step, separating residual gases from the polymer product, and returning said residual gases to the dehydrogenation step for conversion in commingled state withsaid hydrocarbon oil charging stock.

9. A process for producing gasoline of high .anti-knock value from hydrocarbon oilsheavier than gasoline, which comprises vaporizing said hydrocarbon oil, subjecting the resulting vapors to, contact with a dehydrogenating catalyst consisting essentially 'of an inert refractory material supporting a compound "selected from the, group consisting ofcompounds of the elements inthe vleft hand columns of groups 4, 5, and 6in the cooled dehydrogenated products to a separator and absorber wherein fixed gases are removed from the dehydrogenated liquid products, va-

porizing said dehydrogenated liquid products, subjecting the dehydrogenated liquid products in the vapor state and under dehydrogenating conditions of temperature and pressure to contact with a cracking catalyst consisting essentially of silica with a member of the group consisting of alumina, zirconia, vanadia, alumina-zirconia, and alumina-thoria in a second step, cooling the conversion products with reflux condensate produced as hereinafter set forth, introducing said conversion products, together with the cooling oil, to a separating zone wherein liquid residue is separated from the vaporous components, removing 4andn recovering said, liquid residue as a product of the process, subjecting said vaporous components to fractionation to separate fractionated vapors of the desired end boiling point from heavier hydrocarbons whose average boiling point is above that of said fractionated vapors, condensing said heavier hydrocarbons as re'ux condensate inf; the fractionating zone and' introducing it in part to said separator and absorber vas absorber oil and in part. as cooling to said conversion products, condensing and recovering said fractionated vapors to form dis- -tillate and gas, separating normally gaseous hydrocarbons in excess of those required to makeV the desired vapor pressure from the distillate, recovering the stabilized distillate as a product of the process, subjecting said gases, together with said fixed gases produced in said primary step, to polymerization in the presence of a phosphoric acid-containing catalyst underconditions selected to effect substantially complete polymerization of the olens in a third step, 'separat-y ing residual gases from the polymer product. and returning said residual gases to the dehydrogenation step for conversion in commingled state with said hydrocarbon oils.

l0. A process for producing gasoline of high anti-knock value from hydrocarbon oils heavier than gasoline, which comprises vaporizing said.

hydrocarbon oil, subjecting the resulting vapors to contact with. an alumina-chromia dehydrogenating catalyst at a temperature of from 800 to 1200 F. and under a pressure of from sub-l stantially atmospheric to 100 pounds per square inch in a primary step, cooling the dehydrogenated products, introducing the cooled dehydrogenated products to a separator and absorber wherein xed gases are removed from-the dehydrogeriated liquid products, vaporlzing said dehydrogenated liquid products, subjecting the vaporized dehydrogenated liquid products at a temperature of from 800 to 1200 F. andunder a pressure of from substantially atmospheric to 100 pounds per square inch to Contact with a silica-alumina cracking catalyst in a second step, cooling the conversion products with reflux condensate as hereinafter set forth, introducing said conversion products, together with the cooling o il, to a separating zone wherein liquid residue is separated from the vaporous components, removing and recovering said liquid residue as a product of the process, subjectingsaid vaporous components to fractionation to separate fraction'- ated vapors of thedesired end boiling point from heavier hydrocarbons whose average boiling point -i's above that ofv said fractionated vapors, conperiodic table under cracking conditions of temperature and pressure in a primary step, cooling the dehydrogenated products, introducing the' densing said heavier hydrocarbons as reflux condensate in vthe fractionating zone and introducing it in part to said separator and absorber as absorber oil and in part as cooling to said conversion products, condensing and recovering said fractionated vapors to form distillate and gas, separating normally gaseous hydrocarbons in excess of those required to make the desired vapor pressure from the distillate, recovering the stabilized distillate as a product of the process, subjecting said gases, together with said fixed gases produced in said primary step', to polymerization in the presence of a phosphoric acid-containing catalyst at a temperature of from 250 to 450 F. and at a superatrnospheric pressure of from 100 to 500 pounds per square inch in a third step, separating residual gases from the polymer product, and returningsaid residual gases to the dehydrogenation step for conversion in commingled state with said hydrocarbon oils.

l1. A process such as claimed in claim wherein a portion of the reflux condensate is commingled with the hydrocarbon charging oil prior to thevaporizing step.

l2. A process such as claimed' in claim l0 wherein an aqueous uid is introduced to the dehydrogenated liquid products prior to the vaporizing step.

13. A process such as claimed in claim 10 wherein superheated steam is commingled with the vaporized dehydrogenated liquid products.

14. A hydrocarbon oil conversion process which comprises subjecting, the oil, together with normally gaseous parains of at least 3 carbon atoms to the molecule, to catalytic dehydrogenation to produce normally gaseous and normally liquid oleilns, separating from the resultant products an oleilnic gas and an oleiinic liquid, cracking the latter in the presence of a cracking catalyst to produce gasoline and additional gaseous olens therefrom, subjecting said olenic gas vand additionald gaseous olefins produced'by the cracking to polymerization to form normally liquid hydrocarbons boiling in the gasoline range, separating the last-named hydrocarbons from residual gases, and supplying at least a portion of the residual gases to the dehydrogenation step as said normally gaseous parafns.

15. A hydrocarbon oil conversion process which comprises subjecting the oil, together with normally gaseous parailins of at least 3 carbon atoms to the molecule, to catalytic dehydrogenation to produce normally gaseous and normally liquid oleiins, separating from the resultant products an olenic gas and an olenic liquid, cracking the latter in the presence of a cracking catalyst to produce gasoline and additional gaseous olefns therefrom, separating the gasoline and additional gaseous oleiins from conversion products heavier than gasoline, tion of said heavier products to the dehydrogenation step, subjecting said olefinic gas and additional gaseous olens produced bythe cracking to polymerization to form normally liquid hydrocarbone the last-named hydrocarbons from residual gases, and supplying at least a portion of the residual gases to the dehydrogenation step as said normally gaseous parafiins.

16. A hydrocarbon oil conversion process which comprises subjecting the oil, together with normally gaseous paramns of at least 3 carbon atoms to the molecule, to catalytic dehydrogenation to produce normally gaseous and normally liquid oleiins, separating from the resultant products an oleflnic gas and an olefinic liquid, cracking the latter inthe presence of a cracking catalyst to produce gasoline and additional gaseous olens therefrom, separating the gasoline and additional gaseous oleiins from conversion products heavier than gasoline, returning separate portions of said heavier products to the dehydrogenation and cracking steps, subjecting said oleiinic gas and additional gaseous oleiins produced by the cracking to polymerization to form normally liquid hydrocarbons boiling in the gasoline range, separating the last-named hydrocarbons from residual gases, and supplying at least a portion of the residual gases to the dehydrogenation step as said normally gaseous parailins.

CHARLES L.. THOMAS.

returning at least a porboiling in the gasoline range, separating

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