US2947682A - Method of producing a high octane gasoline by reforming a naphtha in two stages - Google Patents

Description

B. S. FRIEDMA METHOD OF PRODUCIN" Aug. 2, 1960 (1 A HIGH OCTANE GASOLINE NAPHTHA IN TWO STAGES BY REFORMING A Filed Dec. 3, 1956 INVENTOR BERNARD S.

FRIEDMAN bed.

employed metal present in these reforming catalysts although other useful platinum metals include rhodium, palladium, iridium which, along with platinum, are the face centered cubic crystallite types of the platinum family as' distinct from the hexagonal types ruthenium and osmium which appear to be of lesser value.

These catalysts can be made by a number of procedures but a particularly effective catalyst is one in which the alumina is obtained through calcination of an alumina hydrate containing at' least about 65 weight percent of trihydrate and about 5 to 35 weight percent of alumina monohydrate and/ or amorphous alumina forms, and advantageously having a surface area of about 350 to about 550 square meters per gram (BET method) when in the virgin state. The minor amount of platinum metal in the catalyst is usually present in finely divided form and is not detectable by X-ray diffraction techniques. Also, these'catalysts are advantageously prepared to afford about 0.10 to 0.5, preferably about 0.15 to 0.3 cc./ gram catalyst.

The platinum metal-alumina catalyst can be employed in any type of reaction system desired, for instance moving or fluidized bed, regenerative or non-regenerative, etc.,

but advantageously the catalyst is disposed as a fixed V In the latter type of operation the size of commercial units is such that essentially adiabatic reaction systems must be employed and in view of this and the endothermic nature of the reforming operation the catalyst is placed in fixed beds in a plurality of reactors, each of which is preceded by means for heating its charge. In fixed bed operations the catalyst is in macrosize form, that is particles generally at least about 4 in length and diameter and preferably not exceeding about in diameter. Particularly when such particles are provided by extrusion, their length may be up to about 1" or more. If the platinum metal-alumina catalyst reforming system be of the regenerative type it can be arranged so that the catalyst of all of the reactors can be regenerated simultaneously or individually. Other variations in the platinum metal catalyst reaction system can be made according to the desires of the operator.

The essential feed to my hydrogen fluoride-boron trifluoride catalyst system contains a substantial part or all of the liquid reformate from the platinum metal catalyst operation and as noted above the over-all hydrohydrogen fluoride-boron trifiuoride reaction system can be returned to the system or various materials such as straight run naphthas, thermal or catalytically cracked gasolines and their fractions can be added. I prefer that the charge to the hydrogen fluoride-boron trifiuoride reaction zone be composed of at least about 50 weight percent of reformate from the platinum metal-alumina catalyst reaction system or a fraction thereof boiling over a range. of at least about 100 F., preferably over a range of at least about 200 F. The hydrogen fluoride- ,boron trifiuoride catalyst can be employed in the substantial absence of added free hydrogen. However, such a gas can be employed to minimize sludge and heavy oil formation. When using hydrogen I prefer about 1 to 10 moles per mole of hydrocarbon feed. Paratfins such boron trifiuoride reaction zone can be separated in a Should agitation of the reaction mixformer.

tained must be suflicient to provide essentially liquid phase reaction conditions as determined by the vapor pressure of the hydrogen fluoride, boron trifiuoride, the reactants and other materials such as hydrogen and reaction products present. Generally, the pressure will be above atmospheric in maintaining the liquid phase reaction. The reaction temperature and time are interdependent factors With a lesser time required to provide products of given octane as the temperature increases. The reaction temperature will usually be in the range of about 50 to 300 F., preferably at least about F.,

with the time required ranging from about /2 minute to 5 hours, preferably about. 10 minutes to 1 hours. Times longer than 5 hours can be employed; however, no particular advantage has been derived thereby which overcomes the obvious economic disadvantages. Inthe reaction zone at least about 0.75, preferably at least about 1.0, mole of boron trifiuoride is provided in the liquid phase per mole of aromatics present and due to economic considerations this ratio will usually not exceed about 5 to 1 or even about 2 to 1. In general I employ at least about 0.5, preferably about 1 to 10, moles of hydrogen fluoride per mole of aromatic constituent. These catalytic components can be added separately but preferably they are introduced into the reaction zone in admixture. The hydrogen fluoride-boron trifiuoride reaction system is usually conducted essentially in the absence of water to avoid having to increase the amount of boron trifiuoride, but frequently there are minor amounts of water present such as those derived through the use of commercially available hydrogen fluoride and boron trifiuoride. The pressure in this reaction system is sufficient to maintain the liquid phase reaction and frequently is in the range of about 400 to 1500 p.s.i.g.

The hydrocarbon product from the hydrogen fluoridenumber of ways. ture be stopped it will generally separate into two phases in the reactor or in any other vessel into which it is transferred as in a continuous, semi-continuous or batch operation. Regardless of where the phase separation takes place or if the formation of these phases is prevented by continuous agitation, the catalyst and hydrocarbon ma terials can be separated by any desired procedure. For instance, the over-all product containing both the catalyst and hydrocarbon can be water washed to removethe Preferably, however, in this type of system I reduce the pressure maintained on the reaction product to allow the boron trifiuoride and then the hydrogen fluoride to distill or be flashed and this operation is followed by water washing to remove remaining catalyst. Alternatively, only the boron trifiuoride might be distilled which would permit the hydrogen fluoride to separate from the hydrocarbon by gravity and the'hydrocarbon layer could then be decanted and water washed.

In another type of system the reaction mixture could be allowed to separate into a lower layer of catalyst containing aromatics which can be recycled to the reaction system in whole or in part; The upper hydrocarbon layer formed could be freed from catalyst by distillation and/or washing with Water or passed through a column layer could be separated as by distillation of the catalyst,

"storms-s v s fan'd the aromatics mightthen be combinedfwith theihydrocarbons of the upperlayer'to providea higher octane product. Small traces of fluoride remainingimthehydrocarbon material can be removed as by pass'age over aluminum or-alumina-at 200-10 400 -F. Various drying procedures could be employedtoseparate water from the hydrocarbon materialsandsuchmaterials could; be stabilized, for instanee-by-theremova1of Cis-arid lighter bonstituefits.

ln the'drawing I have illustrated a simplified flow sheet of an operation conducted -in accordance with my method.

;I n this-=systemstraight run naphtha ischarged by way 0f lined to-heaterl and then-through line-3 to aninitial reactor 4 which-contains .a fixed-.bed of platinum-alumina catalyst. The eflluent from reactor 4 is passed-by way of =-line -5to-heater 6-and then through-line 7 to a second reactor 8 containing platinum alumina catalyst. The rplatinum-alumina catalyst reaction section is of the adiabatic type and rnore than two reactors can be pro- "vided if desired and-in fact usually at least three catalyst .b'eds -in separate reactors will be" employed with each --reactor=having associated therewith a feedrpreheater.

The reformate from reactor S-is passed by way of line 9 to atmospherioflash drum 10 which separates C s and .Qlighter materials which arepassed through -line ll to separator 12. The separator. provides for removal of C a to hydrocarbon constituents through line 13 and hydrogemand methane are passed byway of line 14 to'line 1. -Excess-hydrogen :and methane can be removed from -line:1'4 by wayof line 15.

The aliqu-idwhydrocarbon I reformate from flash drum -l0' is-conveyed by way of line :16'toreactor 17 where it is -eontacted with the hydrogen fluoride-boron trifiuoride Tcatalystenteringbyway-of line 18. The reaction mixture is-continuously withdrawnfrom reactor 17 and passed by way of line :19 to separation section 20. The hydrogen fluoride-borontrifiuoride catalyst separated from the hydrocarbon product can-berecycledby -way of-line 18 to reactor -17. The -liquid hydrocarbon @product obtained -from separation section ztl isconveyed to fractionator 21 by way ofline-22 which" separates -C s and lighter mauterialsoverhead'by way of line2 3, motor -fuel boiling :rangelproducts by way of line it 24, and heavier -hydrocarbon s as bottoms through linezfi. i The-following specificexamples will serveto illustrate uthe-gpresent inventionthowever, they are not to be -con- :sidered limiting.

Example-I iAstraighfrun naphtha is obtained by distillation from crud'efoil and the naphthatypically has an ASTM distillation boiling rangeo'f about 195 to '3 80 F and a RON 7":(ne2t) "of about 44.8. This naphtha is 'fedito a reforming containing "threeessentially adiabatic reactors each :having a' fixed bed-of a platinum-alumina reforming catalyst. -This systemis equipped with means forheating the charge toeach-reactorand the heaters-landreactors are arranged for serial how. The catalyst employed is a .-rplatinum aluminareforming catalyst containing about 0.6 weight percent platinum and manufactured in accordance with application Serial No. 489,726, listed above. The inlet temperatures of thefeed to thethree-catalyst beds are 946, 936 -and 926"=F., respectively, while the pressure ..is about 500 p.s.i.g. Free hydrogen is supplied to the free-amassing to'the 'heaterbe'fore the-first reactor and ."lflie h y'drlogen'is obtained by recycle from the third-reactor Eifiuent stream. 'The molar ratioof hydrogen rich-recycle as to'liydrocarboh feed is approximately 7.3 to 1. 0 while the ever-an spacevlocity is"about"2.26 WHSV. The efiiuent from the last reactor is conveyed to a flash drum operating at 500 p.s.i.g. and is then treated or depropanized to remove C and lighter hydrocarbons by distillation. Inspection on the resulting reformate is as follows:

418. grams of'the reformate is'distilled'to obtain 91I5 weight percent of C gasoline and 4.67 weight percent of butanes (iso-I-normal). lns'pec'tio'non .thefstabilized gasoline fraction is as follows:

ASTM distillation, *F.:

300 grams of the 95 '3 90 F. reformate isplacedina cool 1750 ml. stainless steel Magnedas'h bonibhaVing tapered Walls to give maximum thickness in thebottom half of the bomb. To the cool bomb is added 10 n1oles of hydrogen fluoride. The bomb is sealed and charged with 6.4 moles ofbo'ron trifluoride by pressuring from a 2- liter cylinder fitted with apressure. gauge. Theamounta'of borontrilluc'iride introduced is estimated by interpolation from the data of Kilpatrick and Luborsky, I.A.C.S. 76, 5 866 (1954). While stirring the contents of thewbombwit is heated for 65 minutes to reach F. This temperature is held for 30 minutes and the pressure reaches a maximum of 880 p.s.i.g. The contentsof the bomb .are

his-char ed through the bottomdraw-ofi int'o amixt'u're ofice'and water. IG'ases are conducted through aDry- Ice co'olin'gitra'p, safety trap, water scrubben g'as "sampler "and Wet test meter. The hydrocarbon layeriis separated fr'omth'e 'i'cewater and'the former is 'Washedfthree times with separate 500 cc. portions of water. The Washed hydrocarbon is dried by contact with potassium carbonate. Theproducts obtained are 271.5 .grams of liquid hydrocarbon, 10:5 grains of condnsable 'gas and--3.-2 '1itrs (STP) of drygas. The*condensable gas-and liq'uid are then combined and distilled through-a 12 =glas's helices, vacuum-jacketed distillation -column to separate 4118 weightpercent of C 43 wet gas, 79.3Weight percent of initial*to400 F. overhead gasoline and 7.-17-Weight:p.er-

'cent of a s'tillresidue boiling above 400 F. The'yield of gasoline when corrected forhandlingiand'mechanical losses is about 87.8 weight percent and since=the-gaseline fraction has a 378 F. end point the yield w'o'uld be increased by distilling to 435 F. to obtain the usual nominal 410 end point gasoline. Inspection of the :gasoline fraction is as follows:

ASTM distillation, F

RON 9356 (neat).

. 1 0l (3'. ;'c. 1 l V 'addedfgalfi). Aro n'fafics s '4 9.5%- Olefins 0.4%.

Thus by treating the reformate from the platinum-alumina catalyst system with the hydrogen fluoride-boron trifluoride catalyst the clear research octane number of the 426 grams of the reformate produced in the platinumalumina catalyst system of Example I is placed in the magnedash bomb described in Example I. To the cool bomb is added 5.37 moles of hydrogen fluoride. The bomb is sealed and charged with 3.15 moles of boron trifluoride by pressuring as in Example I. While stirring the contents of the bomb it is heated for 97 minutes to reach 245 F. This temperature is held for 30 minutes and the pressure reaches a maximum of 975 p.s.i.g. The bomb contents are discharged and worked up as in Example I. liquid hydrocarbon, 8.0 grams of condensable gas and 3.07 liters (STP) of dry gas. The condensable gas and liquid are then combined and distilled through a 12" glass helices, vacuum-jacketed distillation column to separate 10.55 Weight percent of C 43 wet gas, 73.1 Weight percent of initial to 400 F. overhead gasoline and 8.46 weight percent of a still residue boiling above 400 F. The yield of gasoline when corrected for handling and mechanical losses is about 79.4 weight percent and since the gasoline fraction has a 370 F. end point the yield would be increased by distilling to 435 F. to obtain the usual nominal 410 F. end point gasoline. Inspection of the gasoline fraction is as follows:

ASTM distillation, F.:

I.B.P 113.

RON 95.0 (neat),

. 100.5 (3 ct. TEL

added/ gal.

Aromatics 49.6% Olefins 0.5%. R.V.P 4.95 lbs.

Thus by treating the reformate from the platinum-alumina catalyst system with the hydrogen fluoride-boron trifluoride catalyst the clear research octane number of the resulting stabilized gasoline was increased by 6.3 num bers and the higher octane product showed a good lead susceptibility.

Example III 5.4 moles of hydrogen fluoride is added to the Magnedash bomb described in Example I. The bomb is sealed and charged with 3.2 moles of boron trifluoride by pressuring from a cylinder as in Example 1. While stirring, the bomb is heated to a temperature of 250 F. and 380 grams of the reformate obtained in the platinum-alumina catalyst operation of Example I is charged by forcing the hydrocarbon feed from a charger under nitrogen pressure. The 250 F. temperature is then held for 22 minutes and the pressure reaches a maximum of 1110 p.s.i.g. The bomb contents are discharged through the bottom draw-01f into' a mixture of ice and water and Worked up as in Example I. The products are 352.0 grams of liquid hydrocarbon, 13.0'grams of condensable gas and 3.95 liters (STP) of dry gas. The condensable gas and liquid are then combined and distilled through a 12" glass helices, vacuum-jacketed distillation column to separate 9.88 weight per cent of C -C W6t gas, 73.18 weight percent of initial to 400 F. overhead gasoline and 9.74 weight percent of still residue boiling over 400 F. Correcting for mechanical and distillation losses the yield of initial to 400 F. gasoline is about 79 Weight percent and this could be increased by taking the distilla- The products obtained are 401.0 grams of g tion overhead to 435 F. to secure the usual nominal 410 F. end point gasoline. Inspection of the gasoline fraction is as follows:

ASTM distillation, F.: r r I I.B.P 111.

E.P 370. f RON 95.5 (neat). R.V.P 5.65 lbs; 'Aromatics 55.2%. Olefins 0.4%.

These data show the substantial increase in octane of the stabilized gasoline afforded by the operation using the hydrogen fluoride-boron trifluoride catalyst.

I claim:

1. In a method for the conversion of a straight run hydrocarbon fraction boiling in the motor fuel range, the steps comprising contacting said hydrocarbon fraction with a platinum metal-alumina catalyst in the presence of free hydrogen at a temperature of about 750 to 1000 F. and a pressure of about 50 to 1000 p.s.i.g to provide a product boiling in the motor fuel range of increased octane value, separating a resulting hydrocarbon liquid productboiling over a range of at least about F., contacting with a catalyst consisting essentially of hydrogen fluoride and boron trifluoride, a hydrocarbon material containing a substantial amount of said separated product, said hydrocarbon material boiling in the motor fuel range and containing about 20 to 80 weight percent of aromatics at a temperature of about 50 to 300 F. and a pressure suflicient to maintain the liquid phase to provide a further increase in the octane quality of the product boiling in the motor fuel range, the contacted hydrogen fluoride, boron trifluoride and hydrocarbon including at least about 0.75 mole of boron trifluoride and about 0.5 to 10 moles of hydrogen fluoride per mole of aromatic in the hydrocarbon and separating a motor fuel boiling range hydrocarbon of high octane quality.

2. In a method for the conversion of a straight run hydrocarbon fraction boiling in the motor fuel range, the steps comprising contacting said hydrocarbon fraction with a platinum-alumina catalyst in the presence of free hydrogen at a temperature of about 825 to 975 F. and a pressure of about to 500 p.s.i.g. to provide a product boiling in the motor fuel range of increased octane value, separating a resulting hydrocarbon liquid product boiling over a range of at least about 200 F. and containing about 30 to 60 weight percent of aromatics, contacting said separated liquid productwith a catalyst consisting essentially of hydrogen fluoride and boron trifluoride at a temperature of about 150to 300 F. and a pressure of about .400 to 1500 p.s.i.g. and suflicient to maintain the liquid phase to provide afurther increase in the octane quality of the product boiling in the motor fuel range, the contacted hydrogen fluoride, boron trifluoride and hydrocarbon including about 1 to 2 moles of boron trifluoride and about 1 to 10 moles of hydrogen fluoride per mole of aromatic in the hydrocarbon and separating a motor fuel boiling range hydrocarbon of high octane quality; i

References Cited in the file of this patent "UNITED STATES PATENTS Burk Aug. 17, 1948 2,513,103 Passino June 27, 1950 2,758,062 Arundale Aug. 7, 1956 2,781,298 Haensel et a1 Feb. 12, 1957 2,849,376 Watson Aug. 26, 1958

Claims (1)

1. 2. IN A METHOD FOR THE CONVERSION OF A STRAINGHT RUN HYDROCARBON FRACTION BOILING IN THE MOTOR FUEL RANGE THE STEPS COMPRISING CONTACTING SAID HYDROCARBON FRACTION WITH A PLATINUM-ALUMINUM CATALYST IN THE PRESENCE OF FREE HYDROGEN AT A TEMPERATURE OF ABOUT 825 TO 975* F. AND A PRESSURE OF ABOUT 150 TO 500 P.S.I.G. TO PROVIDE A PRODUCT BOILING IN THE MOTOR FUEL RANGE OF INCREASED OCTANE VALUE, SEPARATING A RESULTING HYDROCARBON LIQUID PRODUCT BOILING OVER A RANGE OF AT LEAST ABOUT 200* F. AND CONTAINING ABOUT 30 TO 60 WEIGHT PERCENT OF AROMATICS, CONTACTING SAID SEPARATED LIQUID PRODUCT WITH A CATALYST CONSISTING ESSENTIALLY OF HYDROGEN FLUORIDE AND BORON TRIFLUORIDE AT A TEMPERATURE OF ABOUT 150 TO 300* F. AND A PRESSURE OF ABOUT 400 TO 1500 P.S.I.G. AND SUFFICIENT TO MAINTAIN THE LIQUID PHASE TO PROVIDE A FURTHER INCREASE IN THE OCTANE QUALITY OF THE PRODUCT BOILING IN THE MOTOR FUEL RANGE, THE CONTACTED HYDROGEN FLUORIDE, BORON TRIFLUORIDE AND HYDRCARBON INCLUDING ABOUT 1 TO 2 MOLES OF BORON TRIFFLUORIDE AND ABOUT 1 TO 10 MOLES OF HYDROGEN FLUORIDE PER MOLE OF AROMATIC IN THE HYDROCARBON AND SEPARATING A MOTOR FUEL BOILING RANGE HYDROCARBON OF HIGH OCTANE QUALITY.

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