US2410316A - Production of motor fuel - Google Patents

Description

Oct. 29, 1946, c. L. THOMAS PRODUCTION QF MOTORWEUEL Filed Aug. 11. 194].

@MR TSN @Y -UN1TED STATES P rrlarrr oFFIcl-z o `,2,410,316 H j l PRODUCTIN OF' MOTOR Charles L. Thomas, Chicago; Ill., assigner to Unip versal Oil Products Company, Chicago, Ill., a

'corporation of Delaware Application August 11, 1941, serial No. 406,236

6 Claims.

This is a eontinuaticnin part of my co-pending antiknock gasoline by a combination of pyrolytic and catalytic steps which are so integrated as to produce the desired result.

The charging stock 'forl the process may comprise` any petroleum fraction boiling above the range of gasoline such as a gas oil, a topped crude, or a reduced crude, I have found by extensive experimentation the combination of process conditions which will produce the `optimum results desired in my process. ,l My process employs a combination of thermal and catalytic reactions so as to accomplishrthe desired result with a minimum of carbon deposition and catalyst regeneration costs. s In one specific embodiment, my invention comprises a process for the production of a high octane motor fuel by vsubjecting aihydrocarbon oil boiling above the range of gasolineto thermal cracking at a temperature within` the approximate limitsof900 to 1050 F..while at a pressure within the approximate limits of 15 to 150 pounds per square inch when said temperature is Lbelow 975"F. and at a pressurel Within the approximate limits of 15`to about 250 pounds per square inch when the temperature is above975? F.,2fractlon ating the :products from.y said thermal cracking step, separating the gasoline from; the higher boiling products and vsubjecting said gasolinei to thev actionY oan olen isomerizing catalyst 'ata temperature Within the approximate limits of 800 to 1100 F. While at a pressurew'ithin the approximate limits oi substantially atmospheric to about 100. pounds per nsquare inchand for ay time .of contact such that cracking does not-cause more than percentliquid volume loss in said isomerizing step and' separating. from the products "of said olen'isomerizing .step the gasoline fraction asaproduct of the process. n 1 VThe accompanyingv drawingV diagrammatically illustrates on'earrangementof apparatus for ac complishing the process ofmy invention,

.i Referring, now tothe drawing, chargingstock for the process Whichv may icom'prisera 'gas oil, topped crude,y reduced` crude, or the like, is `sup-- plied to the system' through line I,l controlled by Valve 2J from which it is supplied to .pump 3 which discharges throughline 4; pump 5, to, fractionating column 6. Fractionating-column 6 fractionatcs the products of the thermal cracking step in mmnglgd-,State .with the aforesaid `charging stock. This column separates gasoline and gas- .eous products from the higher boiling hydrocarbons, the latter being removed from the column by lWay of line .'I, controlled by valve 8. After passing through valve 8, this fraction is supplied to pump 9 whichdischarges through line I0, controlled vby valve II. After passing through valve n, the 011 is suppnd to heating con l2 which is so disposed as to receive heat from furnace I3.

.used such as, for example, 1000 or 1020 F., the

pressure may be .allowed to exceed 150 pounds per square inch gage, 200 pounds persquare inch gage being avery satisfactory exit pressure in that temperature range. When cracking such stocks as topped crudes, I- preferably employ a temperature of about 940 F. at the exit of the heating coil While utilizing a pressure within the range of 15 to 100 `pounds per square inch gage. When the charging stock is a gas oil, I may employ a somewhat higher temperature, such as,

for example, 950 to about 1000 F. With such a stock very satisfactory results may be obtained operating at a temperature of 980 F. at the exit of the heating coil while utilizing pressures below pounds per square inch but which are preferably at least mildly superatmospheric. In

vthe case of some charging stocks which are particularly high in constituents boiling within the kerosene range, I may operate with cracking above 1000 F. for example, 1020 to 1035 F. and in such cases, the pressure may be equal to 200 or 225 or even asmuch as 250 poundsper square inch gage. When processing fractions consisting largely of constituents Within the kerosene boiling range, a temperature as high as 1050 F. may be used. s

The extent of cracking per pass, in a coil is an important feature in my process. In general, the soaking-time is so adjusted for each stock such that about 5 to 8 or 10 per cent ofthe oil is cracked in the coil for each passage therethrough.

Referringagain to the drawing, the cracked products leaving the heating coil I2 by way of line I4 and after passing through valve I5, are supplied to insulated reaction chamber I6 wherein further cracking is allowed to take place. I find that a very satisfactory operation may be obtainedwhen the extent of cracking in the reaction chamber is about equal to that in the heating coil. The reaction chamber may be entirely omitted with all the thermal cracking taking place in the coil in which case I prefer no more than about to 20 per cent cracking in each pass through said coil.

The products leave reaction chamber I6 by way of line Il and after passing through valve I8 enter vaporizing and separating chamber I9. The pressure in flash chamber I9 may, if desired, be lower than in reaction chamber I6, it being quite commonly reduced to a value mildly superatmospheric but sufficient to permit the subsequent separation steps. The separation process taking place in flash chamber I9 is promoted by quenching the reactants by means Well known but not indicated in the drawing. A side cut removed from fractionator 6 may be used forl this purpose, a portion of the quenching medium being introf duced in line I'I that is the transfer line tothe flash chamber, while another portion may be introduced in the top of flash chamber `in the form of a spray. The liquid separated from the reaction products is removedl from flash chamber I9 by vway of line l20, controlled by valve 2i. This residue constitutes a product of the process. The vapors separated from flash chamber I9 are removed as overhead by way of line 22 and after passing through valve 23, are supplied to fractionating column 6 wherein they. are fractionated in lcommingled state with the charging stock as hereinbefore indicated.

The overhead, from` fractionating column 6, `consisting .of gasoline and normallygaseous products, is removedby way of line24 and after passing .through valve 25, issupplied to line 26 from `which it enters .cooler and .condenser 21. The

mixture of liquid together witht he. undissolved and uncondensedv gases leave .cooler and condenser 27 by way of line 28 and after passing throughr valve 2S, enters receiver and separator A portion of theliquid collected` in receiver 3.a is returnedto fractionating column 6 for cooling and refluxing. This .por-tion of theliquid entersline 3l and after passing through valve 32, enterspumpt-l whichldischarges throughV line 34, vvalve to the top of. fractionating. column .5. Thegases collected in receiver 30 are removed by way, of line Elli, valve 31 and constitute a prode uotofi theprocess. The olenicv constituentspresent in said. gases may be polymerized to form a motor fuel or, if desired, these. olens may be alkylated with isoparafdns also, to form anavia.- tionA fuel. The portionrof the liquid not returned tothe. column for reuxing, is removed fromrecever S by way of line 38 and after-.passing through valve 39, is supplied topump40 which discharges, through line 4I, valve. 42, intoheatT ing coil 43. 'In some. cases, it may be desired to omit the `separation of thegasoline from the nor? mally gaseous products `before. directing the former toi the subsequent reforming step. rIn this method of operation, the overhead product from fractionating column@ is directed through valve 44 into line 38, from which it-is supplied to pump thandi's charged through line 4I, valve 42 into heating coil 43.

. The 'aaselinewith or without the normally gaseous products is heated in coily43'by furnace 45 with a temperature within the. approximate limits of 800-,-1100 F. and at a pressure which may vary from mildly superatmospherie to about 10.0 pounds per square inch at the exit of said heating coil. The heatedvapors are. discharged from coil 43 into line 46 from which theylare directed to either of reactors .A or B. Thecatalyst used in the reforming of the olenic gasoline is preferably one which comprises the oxides of silicon and aluminum such as some of the natural occurring montmorillonite clays after acid purification but more preferably the synthetically prepared composites of silica and alumina. Catalysts consisting of alumina alone may be used although blends .of silica and alumina are to be preferred. More complex composites such as those of silica, alumina, and zirconia may also be used as is the case in the example subsequently cited- The catalyst used in the reforming step becomes contaminated with carbonaceous material and must be regenerated at certain intervals which is accomplished by the oxidation of the deposits `on the catalyst. This oxygen may be supplied in the form of air or air diluted with products of combustion in order to dilute the oxygen and to more accurately control the reactivation temperature. In order `to insure continuity of operation two or more reactors are used so that when one is being used in processing hydrocar- `bonsthe catalyst in the other may be regenerated. The heated charge in line 46`is then directed into line 4l' and after passing through valve 48 is supplied to reactor A wherein the conversion takes place. After the catalyst in reactor A becomes contaminated the charge is then directed into cont-rolled by valve-48.', and supplied to reactor B. Reactors A and B are preferably of the adiabatic type on account of the simplicity of theconstruction of suchreactors. The time of contact depends on the vtemperature and space velocities ofthe order of 5to 50 volumes of liquid charging stock per hour per unit volume of `'catalyst when the temperature is 950 F.,'will give satisfactory results. Lower temperatures, of course, require greater contact .time while temperatures abovey 950 F. permit correspondingly higher space velocities.

TheV principal reactions taking place in the catalytic reforming process of my invention. appear to be the isomerization of the olenic hydrocarbons. Other reactions undoubtedly take place to. a certain extent, the amount of cracking being such that the liquid'volume loss usually equals `two or three percent, the time of contact being so adjusted that the liquid recoveries of.95 percent: and greater vare obtained. While the reactions taking placein the reforming step are not thoroughly understood, it appears that the double bonds formed in the thermal cracking step are not inthe position ofthe most stable equilibrium and the .function ofthe catalyst at least vin part, is'to. shift r"these doublebonds with a yconsequent increase of the octane number ofthe volefinic gasoline. In additionrto the shift'in theA position of the double b ond a certain increase inthe branching of the olenic hydrocarbons undoubtedly takes place. The pressures are so. regulated thatthe amount of polymerization taking place is kept to a minimum., Owing to the difoulty of' operating undersulbfatmcspheric plu'essures` it is usually preferred to -introduce the heated gasoline to the catalyst at pressures which are mildly superatmospheric. When operating at the higher, reforming-temperatures, a pressure asmuch as 10.0 pounds .per` square inchmay'be usedalthough at this-upper limit. the results'are less satisfactory than when reforming at pressures of 5. to 10.4 pounds per'square inchgage.

The reaction products, in case reactor A is being-used in processing, enter line 49; controlled by valve 50, from-which they are supplied-to line 5|. In case reactorB is being lusedin processing,

the reactants enter line ,497, vQfmtrolled `byvalve 50. and are then directedto'line' 51..;1 The-proc-A ess of regenerating a catalyst,contaminatedwith carbonaceous ddepositsis well known inthe art at thepresent time and for .the sake of simplicity, the regeneration circuithas been omitted, from the drawing, The reaction products in linew5l pass through valve 52 from which they are supe plied to stabilizer 53. The stabilizedgasoline leaves column 53 byway of line 54, controlled by valve 55 and constitutes a product of the process. 'Ihe normally gaseous products separated from stabilizer 53,k enter line 56 and after passing through valve 51, are supplied to cooler and condenser 58. The liquid together with the undissolved and uncondensed gases leaves condenser 58 by way of line 59 and after passing through valve 60 are directed toreceiver and separator 6l. The liquid collected in receiver 5I is returned to the stabilizer column for cooling and refluxing. This liquid enters line 62 and afterpassing through valve 53 is directed to pump 64 which discharges through line 65, valve 65, to the top ofthe stabiliaing column. The gases collected in receiver 6l are removed from the system by way of line 61, valve 68.

The following example shows the results obtainable by the process of my invention.. A 25.6 A. P. I. Mid-Continent topped crude was processed in an apparatus corresponding in its essential features to that described in the drawing. The pressure at the exit of the heating coils are varied from 100 to 300 pounds per square inch gage while maintaining transfer temperatures at the inlet of the reaction chambers of 920, 940, and 960 F. A recycle operation was employed in these cases With the residue production amounting to around 35 volume per cent of the topped crude. The gasoline produced in the process was subjected to contact with a catalyst comprising a composite of chemically precipitated and purified silica, alumina and zirconia, the temperatures in the reforming step corresponding to 950 F. while utilizing a space velocity of 15 volumes of liquid per hour per unit volume of catalyst. The resulting gasolines all stabilizing to a 10 pound R. V. P. were as follows:

Table I Octane No Temperature, Pressure, F. entrance pounds per cggged t0 reaction square inch 1939 researeh chamber gage method pounds per square inch gage when said temperaspace.velo.city. Table II ..inclicates.;the4 results I claim as my invention: l

1. A process for the production of ahigh octane motor fuel which comprises subjecting a hydrocarbon oil boiling above the range of gasoline to thermal cracking at a temperature within` the approximate limits of 900 to 975 F. and a pres` sure Within the approximate limits of 15 to'150' pounds per square inch gage, fractionating the products to separate a gasoline and intermediate conversion products and subjecting said gasoline to the action of an olen isomerizing catalyst at an isomerizing temperature within the approximate limits of 800 to 1100 F. and a pressure of from substantially atmospheric to mildly superatmospheric and for a time of contact such that cracking liquid volume loss is maintained below 5% and olefin isomerization is the principal reaction, and separating from the products of said olefin isomerizing step the reformed gasoline as a product of the process.

2. A process for the production of a high octane motor fuel which comprises subjecting a hydrocarbon oil boiling above the range of gasoline to thermal cracking at a temperature Within the approximate limits of 975 to 1050o F. and at a pressure within the approximate limits of 15 to 250 pounds per square inch gage, fractionating the products to separate a gasoline fraction and subjecting said gasoline fraction to the action of an olefin isomerizing catalyst at an isomerizing temperature Within the approximate limits of 800 to 1100 F. and a pressure of from substantially atmospheric to mildly superatmospheric and for a time of contact such that cracking liquid volume loss is maintained below 5% and olefin isomerization is the principal reaction, and separating from the products of said olefin isomerizing step a gasoline fraction as a product of the process.

3. A process for the production of a high octane motor fuel by a combination of thermal cracking and catalytic reforming which comprises subjecting a hydrocarbon oil boiling above the range of gasoline to thermal cracking under such conditions of temperature and pressure that the cracking takes place at a temperature within the approximate limits of 900 to 1050D F. and at a pressure within the approximate limits of 15 to 150 ture is below 975 F. and at a pressure within the approximate limits of 15 to about 250 pounds per square inch gage when the temperature is above 975 F. and for such a period of time that not more than 20 weight percent of the oil is cracked per pass, fractionating from the products of said y thermal cracking step a gasoline fraction and subjecting said gasoline fraction to the action of an olen isomerizing catalyst at a temperature Within the approximate limits of 800 Ato 1100 F. and at a mildly superatmospheric pressure .and for a time of contact equivalent to an hourly liquid space velocity of about 5 to 50 volumes of gasoline per hour per volume of catalyst when the reacting temperature is 950 F. so as to cause less than 5 percent liquid volume loss in said isomerizing step and separating from the products of said olelin isomerizing step the gasoline fraction as the product of the process.

4. A method of producing high octane number motor fuel which comprises subjecting a hydrocarbon oil boiling above the range of gasoline to thermal and non-catalytic cracking at a temperature of about 925 F. and a pressure Within the approximate limits of 50 to 250 pounds per square inch, fractionating the products to separate a gasoline therefrom, subjecting said gasoline to contact with an olefin isomerizing catalyst at a temperature Within the approximate limits of 850 to 1100`F. and a pressure from about atmospheric to about 100 pounds per square inch and at a space velocity within the approximate range of 5 to 40 volumes of gasoline (liquid basis) per Volume of catalyst space lperrhour such that a Volume percent liquid yield -ofmotor fuel of about 95 and Agreater is obtained.

5. A process forincreasing thefoctane number of a thermally and non-catalytically cracked'gasoline which comprises subjecting said gasoline to contact with an olefiny isomeriZing-catalystwat a temperature within the approximate limits of y800" to 1100 F. and lat a space velocity withinthe approximate range of 5 to 50 Volumes of gasoline (liquid basis) per Volume of catalyst space per hour suchthat a Volume per cent liquid yield of motor fuel of about 95 and greater is obtained. 6. A process for increasing the octane number of a thermally and non-catalytically cracked gasoline which comprises subjecting said gasoline to contact with an olen isomerizing catalyst at a temperature Within the approximate limits of 850 to 1100* F. and at a space velocity Within the approximate range of 5 to 40`volumes of gasoline (liquid basis) per Volume of catalyst space per hoursuch that a volume per cent liquid yield of motor fuel of about 95 and greater is obtained.

CHARLES L. THOMAS.

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