US2294584A - Catalytic treatment of hydrocarbon oils - Google Patents

Description

Sept, 1,1942. c. l.. THOMAS d CATALYTIC TREATMENT OF HYDROCARBON OIL Filed Jan. 30. 1939 lNvr-:NTOR

CHARLES L. I 'HOMAS TTORNEY Patented Sept. 1, 19,42

UNITED STATE lCATALYTIC TREATMENT or mimosanoN ons Charles L.

Universal Oil Products Thomas, Chicago, Ill., assignor Company, Chicago,

to lil.,

a corporation of Delaware Application .tammy so, 1939, serial No. 25am claims. (ci. 1st-49) This invention relates particularly to the manufacture of gasoline from hydrocarbon oils heavier than gasoline and is more specifically concerned with a process which provides for converting hydrocarbon oils of a higher average boiling point and a higher specic gravity than gasoline, and which contain hydrocarbonsj'that are not readily vaporized under the conditions employed when catalyticallycracking clean vaporous stocks, to lower specic gravity and lower average boiling point hydrocarbons than the charging stock and/ or gasoline of good antiknock properties, and, in addition, gases relatively rich in polymerizable olefns.

`The charging stock for catalytic cracking processes preferably comprises a gas-oil or a readily vaporizable hydrocarbon oil because it has been found desirable to carry the reaction out substantially under vapor phase conditions. In other processes the charging stock, which con-'- .tains relatively high-boiling, non-vaporizable fractions, is commingled with the conversionv products from the catalytic cracking reaction as cooling oil followed by fractionation of the commingled materials to separate a gasoline product, an intermediate fraction which may be substantially completely vaporized and which is good starting material for catalytic cracking in "the vapor phase, and non-vaporizable residue. In the latter process, however, the yields obtained do not correspond to the optimum yields from a given charging stock, and it is the purpose of this invention to improve the yields of gasoline by subjecting the relatively high-boili ing, non-vaporizable hydrocarbon fractions in lthe charging stock, together with non-Vaporizable conversion products produced in the process, to catalytic conversion in the liquid phase.

This invention, therefore, provides an improved process for catalytically cracking high-boiling hydrocarbons in two stages, the rst stage being v carried out substantially under liquid phase conditions and the second stage substantially under vapor phase conditions with provision for separation of non-vaporous residue from vaporous components between the two' stages.

It has been found that hydrocarbon oils containing substantial quantities of relatively" highboiling fractions may be converted to oils of a relatively lower average boiling point and lower specific gravity than the charging stock by catalytic means,; and that the catalytic reaction may be so regulated that relatively small quantities of carbon are depositedupon the catalyst in 'the' specific form of apparatus in which the process.

nrst stage. This may be accomplished by substocks produced,k in the Amingling the same order to materially reduce the coking tendency` superatmospheric pressure relative to the tem,

pe'rature and pressure employed when catalyti-a cally cracking` clean readily vaporizable stocks so .that the catalyst is continuously subjected to the washing action' of the liquid materialswhile the processing is taking place and the amount of carbonaceous materialsl deposited upon the catalyst is substantially reduced with provision for removing the coke forming materials in either a coke chamber or a separating chamber or both after the first stage and for Pcatalytically cracking the clean vaporous rst stage in a second stage. In addition, it has been found that hydrocarbon oils subjected to such treatment yield substantially more light oils and/ or gasoline than is obtained in any of the known processesiwhich operate on the vapordus fractions obtained.Y from the hydrocarbon charging .stock only. The present invention.-further provides Afor recycling a portion of the relatively high-boiling liquid conversion products produced in the process by com- @With the charging stock in of the charging stock.

In one specific' embodiment the present invention comprises subjecting relatively heavy reux liquid phase in a primary stepfurther treating the products to separate Ivapors from the nonvaporous residue and recovering the latter as coke, subjecting said vapors to catalytic cracking in a second stagegicooling the cracked products from the second stage by introducing relatively light reux condensate thereto, subjecting the mixture of cracked products and cooling oil to fractionation along with charging oil to produce overhead vapors of gasoline boiling range which are condensed and collected, relatively light reux condensate used as said cooling oil, and heavy reflux condensate cracked in said primary stage.

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 characteristic operations in connection with the attached dial grammatic drawing. ,The drawing illustrates one of the invention may be conducted.' However, the application of the features of the invention to other specic types of apparatus will be readily further provisions made condensate to catalytic cracking in substantially apparent to' those familiar with the catalyticv Referring to the drawing, heating coil I is dis posed within a furnace 2 by means of which the required heat is supplied to the commingled oils passing through the heating coil to bring them to the desired temperature, preferably at a substantial superatmospheric pressure. In the particular case here illustrated, it is preferred that the heat supplied to the commingled oils passing prepared by precipitating silica hydrogel from'a solution of sodium silicate by acidifying with an through heating coil Iv be sufficient to 'raise them l to the desired temperature but that the time required in reaching such a temperature be relatively rapid in order to suppress any thermal cracking reaction.

The heated products, substantially in the liqu'id phase, are vdischarged from heating coil I through line 3 and valve 4 into catalytic reactor 5 wherein they are contacted with a cracking catalyst disposed therein. I

Preferably and in the case here illustrated, catalytic reactor 5 comprises a plurality of small A diameter reactor tubes 6 connected in parallel between upper and lower headers 'I and 8 and' is disposed within a -heating or cooling zone 9. Catalytic crackingA is an endothermic reaction requiring heat and, therefore, in order to obtain -best results heat must be supplied to the material undergoing conversion within reactor 5. It has been found that best results are usually obtained when employing fluid heating means which preferably comprises hot combustion gases-which may be introduced to zone 9 through duct I0, passed in indirect heat exchange relationship with the materials passing through reactortubes 6, after which they are discharged from the upper portion of zone 9 through duct I I. l

In catalytic endothermic reactions, such as catalytic cracking, carbon deposits upon the catalyst atv a relativelyrapid rate and tends to decrease the catalyst activity, this fact being even more apparent when the charging stock comprises relatively high-boiling, non-vaporizable residual t hydrocarbon oils. In order to obtain best results, relatively short operating periods are employed;

i. e., the catalysts are subjected to contact with the materials undergoing conversion for a'relatively short time and are then reactivated in apcase it is preferred that a plurality of reactors be employed, each disposed within a separateheating or cooling zone,4 and in order that the operation may be made continuous, reactivation may be accomplished in some of the reactors While Iproximatey the same length of time. In this acid, such as hydrochloric acid, for example, subsequently treating and washing the silica hydrogel to remove substantially all of the alkali metal ions, suspending the puried silica hydrogelin a solution of aluminum salts and depositing the alumina hydrogel upon the suspending silica by the addition of volatile basic precipitants, such as, for example, ammonium hydroxide, ammonium carbonate, or ammonium sulphide. After the alumina hydrogel has been deposited upon the purified hydrated silica hydrogel, the material is dried, formed into pellets, when desired, and calcined at a temperature of approximately 850 to 1000 F.

Although the present process has been found to operate very effectively in catalytically crackingV petroleum oils when employing a catalyst consisting of silica composited with 15% alumina, the process is not limited to this particular composition of catalyst but may employ other composite catalysts of a refractory character, such as, for example, silica composited with a component selected from the group comprising zirconia, vanadia, alumina-zirconia, or aluminathoria, and acid-treated clays may also be employed. The catalysts referred to above arenot exactly equivalent in their reaction and are not to be considered as absoluteV substitutes one for the other, which fact will be more or less apparent to those skilled in the art.

In the particular case here illustrated, when the catalysts are reactivated the now ofA hydrocarbon oil is stopped and suitable reactivating gas mixtures at an elevated temperature and containing regulated quantities of oxygen are introduced to catalytic reactor 5 through line to storage or further use" as a reactivating' gas mixture or a portion or all may be cooled and recirculated as the reactivatingggas mixture or the whole may be discharged to the atmosphere as desired. AWhen reactivating the catalyst the reaction is exothermic and, therefore, suitable means must be employed to dissipate the heat generated therein. In this case it is preferred to employ cooled combustion gases which are supplied to zone-9 through'duct I0, passing therethrough in indirect heat exchange relationship with the ow of reactivating' gases in resist in general of uniform sized pellets of specially prepared silica composited with the alumina, the amount of alumina being varied lto suit 'requirements depending upon the stock to be treated and the operating conditions employed. As a actor tubes 5, and are discharged` therefrom through duct II. The vaporous and liquid conversion products are discharged from reactor 5 through line I4 and valve II and may be directed all or in part through valves I8 and I 9 to coke chamber 20.

However, .when the conversion a products fromcatalytic reactor 5 lack sufllcient The heated materials are` ascesa@ l y ieat to coke material deposited within coke chamber 20, additional heat may be acquired by neans of furnace'24. Inthis case, all or a por- ;ion f the conversion products in line I4 are iirected through line 2| and valve 22 to heating :oil 23.l Heat is supplied to the conversion products passing through heating coil 23 by means of furnace 24 and theyare discharged therefrom through line 25 and valve 26 into line ld and introduced to coke chamber 20, as previously described.

The liquid conversion products introduced to coke chamber in commingled state with the vaporous conversionproducts are reducedto substantially dry coke therein, and the' vaporous conversion products, together with the vapors evolved within coke chamber 20, are withdrawn from the upper portion thereof through line 2l and may be introduced allor in part to separating chamber 3| by way of linel 28, valve 29, and line 30, or the vaporous materials may be directed through valve 32 and treated, as subsequently described,

Preferably, a plurality of coke chambers are employed, although only one is shown in the diagrammatic drawing. in order that the coking operation may be made continuous with respect to the balance of the apparatus by alternately coking and cleaning eachgchamber. In the case lhere illustrated, before coke chamber 20 is cleaned of the coke deposited therein, steam is preferably introduced through line 33 and valve 34 in order to purge the vessel of hydrocarbon vapors.

In case it is desirable to make liquid residue instead of coke, coke chamber 2d may be byheating or cooling ,zone 6i.

.passed and the conversion products in line ld directed through line 28, valve 35, and line 3@ to separating chambery 3l. The preferred method, however, consists of introducing' the conversion products to coke chamber 2d and supplying the vaporous materials from coke chamber 2@ to separating chamber 3l. ln separating chamber 3l thehigh-boiling, coke-forming materials carried over with the vaporous materials from coke chamber 2d are separated from the vaporous materials and collected in the bottom. The high-boiling, coke-forming materials are directed from the lower portion of separating chamber 3i through line 3S and valve 3l to pump 3d which discharges through line 39, and all or a `portion of these materials may be directed through valve it to cooling and storage. In the preferred process, however, these materials are returned to coke chamber 2t by way of line di and valve d2 in order that they may be reduced to coke. f t

The vaporous materials separated in separating chamber di are withdrawn from theupper portion thereof through line d3 and are directed through valve @d into line 2l. The vaporous materials in line 2l are preferably heated to the desired reaction temperature in furnace 5l, however, when and if these materials are at the desired reaction temperature they may' be directed through valve t5 and valve d to reactor dl. Preferably, however, these vaporous materials in line 2l are subjected to heating in furnace 5l, this being accomplished by directing them through line d8 and valve di? toheating coil 5d.

discharged. from -heating coil 5t through line 52 and valve 53 into low pressure employed in this catalytic reaction, and in'order to reducethe eective pressure on the hydrocarbon vapors, steam may be intro-f duced to `.the vaporous products either before heating coil by way of line 5t and valve 55 or after heating coil 50 by way of line et and valve tl. v t

In the case here illustrated, catalyticvreactor 41 is constructed similarly to catalytic reactor 5 and lconsists of relatively small diameter reactor tubes 58 connected in parallel between upper and lower headers 59 and 60 and disposedv within a As in the case of catalytic reactor 5,. the preferred form of heating the materials within catalytic reactor 4l is by fluid heating means. Hot combustion gases, comprising the troduced to zone'6l by Way of duct 62, passed in indirect heat exchange relationship with the vaporous materials passing 5t, and discharged from zone 6i by Way of duct 63. i

Catalysts are preferably employed in catalytic reactor rtl which have been found to be highly efficient in the catalytic cracking of hydrocarbon oil vapors to produce optimum yields of gasoline. The preferred catalysts for edecting catalytic" cracking of vaporous materials consist in general of pellets or materials as were previously described, and, also, the methods previously disclosed for preparing catalysts are employed for preparing these cata lysts.

,Th activation of the catalysts disposed vwithin reactor dil is accomplished by stopping the ow of vapors to reactor tl by means of valve it and introducing suitable reactivating gas mixtures at an elevated temperature and containing regulated quantities of oxygen by way of line td, valve 65, and line 2l. The reactivating gases pass through reactor tubes 5il,'and due to onidation the carbon deposited upon the catalysts disposed therein is caused to burn. The resulting mixture of combustion gases and reactivating gases is discharged from reactor dl through line SS and is directed through line ti and valve t@ to storage for further use or elsewhere las desired. Duringreactivation, in order to dissipate "the heat generated in the exothermic reaction,

cooled combustion gases are preferably supplied to zone div by ,way lof duct t2, passed in indirect' heat exchange relationship with the reactivating gases in reactor tubes 58, and discharged by way of duct In order that the catalytic cracking reaction carried out in catalytic reactor ll may be made lcontinuous with respect to the balance of the I equipment, and because of necessity the reactors are operated on a relatively short-time schedule, a plurality of reactors are preferably employed, each disposed within a separate -heating or cooling zone. In this case the reactivation is carried out in some of the reactors while the others are processing. Although the type of reactor described above hasbeen found to have 'many advantages when employed in this particular process, various other types of reactors 'may ,be

line 2i! by means of which they.are supplied l to reactor ll, as previously described. In order to maintain the charge to catalytic reactor di in the vapor state under the relatively employed without departing from the broad scope of the invention. The conversion products discharged from catalytic reactor lll are directed through line 66 and valve 69, cooled to a relatively low temperature by commingling with the same a suitable cooling oil and the conversion products, together with the cooling oil introduced to fractionator it.

iiuid heating means, may be in through reactor tubes the upper portion of granules of the same flux condensate infractionator 10. i reflux condensate is withdrawn from an inter- The preferred method, however, for introducing i charging stock to the process consists in com` mingling at least a portion ofthe charging stock in line 16 with the conversion products discharged from catalytic reactor 41 in line 86 as cooling oil.y 'I'hi's may be accomplished by directing all or a portion of the charging stock in line 16 through line. 18, valve 19, and line into line 66.

In fractionator 10, from the commingled ccnversion products and cooling oil (and when oil other than charging stock is employed as cooling oil, thecharging stock), fractionated vapors of the desired end boiling point are separated from the higher boiling liquid conversion products and the higher boiling fractions of the charging stock.

Fractionated vapors of the desired end boiling point are directed from the upper portion of fractionator through line 85 and valve 86 to condenser 81. The resulting gas-containing distillate, together with undissolved and uncondensed gases discharged from' condenser `81, are directed through line 88 and valve 89 to receiver 90. Undissolved and uncondensed gases collected and separated in receiver 90 are directed from the upper portion. thereof through line 9| and valve 92 to collection and storage or `else-H where as desired. A portion of the distillate collected and separated in receiver 90 is directed through line 93 and valve 94 to pump 95 which f discharges through line 96 containing valve 91 into the upper portion of fractionating zone 12 for refluxing and cooling therein. The balance ofthe distillate collected and separated in receiver `90 is directed from the lower portion thereof through line 98 and valve 99 to stabilizas tion or to storage desired.

The higher boiling hydrocarbons, comprising fractions of the conversion products and fractions of the charging stock whose average boiling point is above that of the fractionated vapors, are selectively condensed as light and heavy re- The light yor to further treatment as mediate point in fractionator 10 and is directed through line |00 and valve |0| to pumpA |02. Pump |02 discharges through line |03 and a portion of the refluxcondeisate in line |03 may be directed through line |05 and valve IUS-and commingled with the conversion products in line 66 as cooling oil prior to their introduction` to fractionator 10. The balance or all of the light reflux condensate in line |03 may, when desired, be directed through line |01 and valve |08 into line 21 for subsequent conversion -in commingled state with the vaporous materials removed from separating chamber 3|'. Light reflux condensate is preferably employed as a refluxlng and cooling mediumin separating chamber 3|, and this may be accomplished by directing at least a portion of the light reflux condensate in line |03 through valve |04 into the upper portion thereof.

The heavy reflux condensate collected in the I lower portion of Iffractionator 10 is withdrawn therefrom and supplied to heating coil for treatment, as previously described, by way of line 80,

valve 8|', pump 82, line 83, and valve 84.

the heating coil to which the heavy reflux condensate is supplied. The coke chamber and separator may employ a superatmospheric pressure substantially the same or somewhat reduced 4relative to the superatmospheric pressure empl yed on the outlet of the rst catalytic crackin stage. The heating coil to which the clean vaporous materials from the separator are supplied may employ an outlet temperature ranging, for example, from 8'00 to 1200 F. and a superatmospheric pressure of from 20 to 100 pounds ory more per square inch. "I'he conversion products discharged vfrom the second catalytic cracking stage are preferably cooled to a temperature ranging, for example, from 600 to 800 F. or at least to a temperature suiiiciently low to substantially arrest any thermal cracking reaction. The fractionator following thel second stage may utilize a pressure substantially the same as that `employed at the outlet of. the second catalytic cracking stage.

Aslan example of one specific operation of the process as'it may be accomplished in an apparatus such as illustrated and above described is approximately as follows:

Heavy reiiux condensate produced within the system was subjected to contact Ain thefliquid phase with a silica-alumina cracking catalyst at a temperatureo'f apprximately 9301F. and under a superatmospheric pressure ofapproximately 300 pounds per square inch. The conversion products from this stage were introduced to a coking zone operated at a superatmospheric pressure of apthe non-vaporous residue was reduced to substantially dry coke. The vaporous materials removed frorn the coking zone were introduced to a. separating zione, operated under vsubstantially the sa'me superatmospheric pressure as thecoking zone,k toA remove entrained liquids from the vaporous materials and the former returned to the coking zone. The vaporous materials were removed from the separating zone and subjected lto contact in the vapor state with a silicay ing stage and was subjected to fractionation therein in commingled state with the charging stock comprising a 25 A. P. I. gravity Mid-Continent topped crude oil t'o separate fractionated va`pors of the desired end boiling point from the higher boiling liquid conversion products and the higher boiling liquid fractions of the charging proximately 75 pounds per square inch wherein` i commingling therewith vresidue and recovering stock and the fractionated vapors recovered as a product of the process. The higher boiling liquid conversion products and the higher boiling liquid fractions of the charging stock were selectively condensed as light and heavy reflux condensate and the latter subjected to conversion in theiirst mentioned catalytic cracking stage, as previously described. A portion oi the light reflux condensate was commingled with the conversion products from the second mentioned cracking stage and the balance of the light reiiux condensate subjected to conversion in the second mentioned catalytic cracking stage. This operation yielded approximately 65% of 81 octane number gasoline by volume of the charge and approximately 60 poundsof coke per barrel of charge.

I claim as my invention:

1. A process for the production of hydrocarbon oil of lower average boiling point than the charging stock and gas of relatively high polymerize able olefin content from hydrocarbon oil with an average boiling point above that of gas-oil, which comprises subjecting heavy reilux condensate, produced as hereinafter set forth, to contact,` in the liquid phase'at a temperature ranging from r100 to 1100 F. and under a superatmospheric pressure of from less square inch, with a silica-alumina cracking catalyst in a primary stage, separating the conversion products discharged from said primary stage into vaporous components and non-vaporous residue andrecovering the latter as a product of the process, subjecting said vaporous components to contact, in the vapor phase ata temperature ranging from 800 to 1200o F. and a pressure of from substantially atmospheric to 100 pounds per square inch, with a silica-alumina cracking catalyst in a second stage, cooling the conversion products discharged from said second stage by charging stock for the process, fractionating the commingled conversion products and charging stock to separate gas and gasoline from the higher boiling hydrocarbons, recovering said gas and gasoline as products of the process, selectively condensing and collecting said higher boiling hydrocarbons as light and than 200 to 700 pounds per primary stage process, fractionating the commingled conversion products and charging stock to separate gas and gasoline from the higher boiling hydrocarbons, recovering said gas and gasoline as products of the process, selectively condensing and collecting said, higher boiling hydrocarbons as light and heavy reflux condensate, subjecting said light reflux condensate to ,conversion in commingled state with said vaporous components in said lsecond stage, and subjecting said heavy reux condensate to conversion in said first stage.

3. A conversion process which comprises subjecting heavy cracking underl suiilcient superatmospheric pres- "ure to maintain a substantial portion thereof in liquid phase and in the presence of a cracking catalyst comprising silica and alumina, separating the thus treated oil into vapors and residue, subjecting the separated vapors to further catalytic cracking at higher temperature and under lower pressure than and independently of said heavy oil, ractionating the resultant conversion products to form light reflux condensate and a heavier reflux condensate, supplying said heavier reflux condensate to the first mentioned cracking.

step, and supplying thev light reflux condensate to the second mentioned cracking step.

4. A process for the conversion of heavy hydrocarbon charging stocks which comprises subjecting heavy reux condensate, formed as hereinafter. set forth, to relatively mild cracking in a under sufficient pressure to maintain a substantial portion thereof in liquid phase and in the presence of a siliceous cracking catalyst,'separating the thus treated reiiux condenV sate into vapors and residue, subjecting the separated vapors to further catalytic cracking in a heavy reiiux condensate, subjecting said light reflux condensate g to conversion in commingled state with said vaporous components -in said second stage, and subjecting said heavy reflux con- .densate to conversion in said rst stage.

the production of hydrocarbon 2. Aprocess for oil of lower average ing stock and gas able olefin content average boiling point comprises subjecting boiling point than the chargof relatively high polymerizfrom hydrocarbon-oil with an above that of gas-oil, which heavy ren'ux condensate,

produced as hereinafter set forth, to contact, in

the liquid phase at a temperature ranging from '700 to 1100 F. and under a. superatmospheric pressure of from less than 200 to '700 pounds per square inch, with a silica-zirconia cracking cata.- lyst in a primary stage,` separating the conversion products discharged from said primary stage into vaporous vcomponents and non-vaporous square inch, with a silica-zirconia cracking Ycatalyst in a .second stage, cooling the conversion products discharged from said second stage by colina therewith charging stock for the the latter asa product ofl secondary stage at higher temperature and under lower pressure than and independently o! the reflux condensate. in the primary stage, fractionating the resultant conversion products in ladmixture with the charging stock for the process to separate gasoline and gas and to formv a light reflux condensate and a heavierreiiux condensate, supplying said heavier reflux condensate to the primary stage and supplying said light reflux condensate to the secondary stage.

5. The process as dened in 'claim 4 further characterized in that the 'charging stock is commingled with said conversion products promptly upon stage whereby to 6. The process as denned quench said products.

ing the thus treatedjoil into vapors and residue,

- subjecting the separated vapors to further cata- :lower pressure than and heavier refiux condensate.

lytic cracking at higher temperature and under heavy oil, fractionating the resultant conversion products to form lightrerlux condensate and a supplying said heavier reflux condensate to the first mentioned cracking step and supplying said light reflux condensate to the second mentioned cracking step.

8. The process or claim 3 further characterized in that the catalyst contains zirconia. j

CHARLES I. THOMAS.

hydrocarbon oil to relatively mild discharge of the latter from the secondary in claim 4 further' characterized in that the catalyst in both said independently of said

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