US3133012A - Combination catalytic reforming process - Google Patents

Description

May 12, 1964 c. v. BERGER COMBINATION CATALYTIC REFORMING PROCESS Filed June 28, 1961 38m SE G ma uo r ant mmm Fractionaror .Sfabi/izer \mwmmxmas r Wm N V E /V TOR Charles V. Berger A TT'OR/VEYS 2A United States Patent ()fiice 3,133,0l2 Patented May 12, 1964 3,133,012 CUMBHNATIGN CATALYTIC REFGRMING PRGCESS Charles V. Berger, WesternSprings, Ill, assignor to Universal (Bil Products Company, Des Piaines, llL, a corporation of Deiaware Filed June 28, 1961, Ser. No. 120,339 5 Claims. (Cl. 208-05) The present invention relates to a process for the catalytic reforming of hydrocarbons and various mixtures of hydrocarbons. More specifically, the present invention is directed toward the solution of a particular problem arising as the result of the necessity to produce a motor fuel gasoline having rigid specifications in regard to octane rating and volatility, imposed thereupon. The method of the present invention involves the fractionation of a catalytically reformed liquid product efiiuent, with subsequent blending of the resulting fractions in such a manner as results in a final product of the desired quality.

Rigid specifications have been expressly imposed upon motor fuel gasolines for utilization in the European market. These specifications require the production of a high octane gasoline possessing an unusually high degree of volatility. The octane rating required is of the order of about 98.0 to 100.0, or more (F-l Clear); the volatility factor, being a measure of the quantity of hydrocarbons Within the motor fuel which are distillable at a temperature below 212 F., is required to be at a minimum of about 45.0%, and preferably as high as 50.0% by a volume. A motor fuel, or aviation gas, having these characteristics is particularly required in normally cold climates where engine start-up is difficult to achieve with standard high octane fuel having only normal volatility.

Of the various types of hydrocarbons normally present in a motor fuel gasoline, parafiins, olefins, naphthenes, and aromatics, the aromatic hydrocarbons possess the highest octane blending values, and, in order to produce a motor fuel having an octane rating in excess of about 98.0, at least 58% by volume of aromatics is required. Similarly, for an octane number of 100, at least 62% of aromatic hydrocarbons are required. Many processes are currently available for the conversion of petroleum hydrocarbons into relatively high octane gasolines, such processes including thermal cracking, catalytic reforming, catalytic cracking, alkylation, etc. The catalytic reforming of petroleum hydrocarbons affords the greatest opportunity to produce a final product highly concentrated in aromatic hydrocarbon, and is, therefore, widely utilized throughout the petroleum industry. However, notwithstanding the applicability of a catalytic reforming process, the foregoing rigid specifications as to octane rating and volatility are so inconsistent with each other, that the required product quality is virtually unattainable. All of the aromatic hydrocarbons, possessing the highest octane blending values, have normal boiling points above about 212 F., with the exception of benzene which has a normal boiling point or" about 176 F. As stated above, between about 58.0% and about 62.0% by volume of aromatics are required to give an octane rating in excess of about 98.0. Since benzene is not formed nearly to the extent of other aromatics, it is evident that on the one hand the specifications require that at least 45.0% of the gasoline be distillable below a temperature of 212 F.

(by standard ASTM distillation methods), while on the other .hand, the gasoline must consist of some 60.0% by volume of aromatics, most of which boil above 212 F. in order to meet the requirement directed toward the octane rating. Notwithstanding that aromatic hydrocarbons have the tendency to form azeotropic mixtures with parafiins, resulting in a lowering of the boiling point thereof, extreme difiiculty exists in reconciling the foregoing contrary requirements.

The object of the present invention is to provide a solution to the rather complex problem hereinabove set forth. I have found that a motor fuel gasoline, having characteristics which far exceed the foregoing rigid specifications, is readily obtainable through a combination process involving catalytic reforming and detailed fractionation.

Therefore, in a broad embodiment, the present invention relates to a process for producing high octane gasoline of which at least about 45 .0% by volume is distillable at a temperature below 212 F., which process comprises fractionating a high octane, catalytically reformed product efiluent of lower volatility into a first fraction obtained at a cut-point less than about 9 0 C., asecond fraction obtained at a cut-point less than about 120 C. and a third, bottoms fraction; combining at least a portion of said first fraction with at least a portion of said second fraction to yield a high octane mixture of which at least about 45.0% by volume is distillable below a temperature of 212 F., and combining the remainder of said first and second fractions with said third bottoms fraction to yield a high octane blending stock of lower volatility.

In another broad embodiment, the present invention involves a process for producing a high octane gasoline of which at least about 45.0% by volume is distillable below a temperature of 212 F., which process comprises fractionating a high octane, debutanized'catalytically reformed product eflluent of lower volatility into a first fraction obtained at a cut-point less than about 90 C. and substantially free from toluene, a second fraction obtained at a cut-point less than about 120 C. and containing substantially all the toluene initially present in said debutanized reformed product effluent, and a third, bottoms fraction; combining at least a portion of said first fraction with at least a portion of said second fraction in which the blended ratio of said first fraction to said second fraction is less than that in which they wereinitially present in said debutanized reformed product efiluent, to yield a high octane mixture of which at least at least about 45.0% by volume is distillable below a temperature of 212 F., and combining the remainder of said first and second fractions with said third bottoms fraction to yield a high octane blending stock of lower volatility.

A limited embodiment of the present invention is directed toward a process for producing a gasoline having an F1 Clear octane rating in excess of about 98.0, at least 45.0% by volume of which gasoline is distillable at a temperature below 212 F., which process comprises fractionating a debutanized catalytically reformed product eflluent, of which less than about 45.0 by volume is distillable at a temperature below 212 F., into a first fraction obtained at a cut-point of about C. to about C. and substantially free from toluene, -a second fraction obtained at a cut-point of about C. to about C. and containing substantially all the toluene initially present in said reformed product, and a third bottoms fr-action substantially free from toluene; combining at least a portion of said first fraction with at least a portion of said second fraction in a volumetric ratio less than that in which they were initially present in said debutanized, catalytically reformed product, the resulting mixture having an octane rating in excess of about 98.0, and of which at least 45.0% by volume is distillable at a temperature below 212 F., and combining the remainder of said first and second fractions with said third bottoms fraction to yield a high octane blending stock of which less than about 45.0% by volume is distill-able at a temperature below 212 F.

The present invention is particularly directed toward a combination of catalytic reforming and detailed fracdonation for producing high octane gasoline having high volatility. The combination process involves catalytically reforming a low octane hydrocarbon mixture of low volatility at reforming conditions selected to produce a debutanized liquid product effluent having an octane rating in excess of about 98.0 (F-l Clear), of which liquid product less than about 45.0% by volume is distillable at a temperature below 212 F., fractionating said product efiiuent into a first fraction obtained at a cut-point less than about 90 C. and substantially free from toluene, a second fraction obtained at a cut-point less than about 120 C. and containing substantially all the toluene initially present in said reformed product effluent, and a third, bottoms fraction; combining at least a portion of said first fraction with at least a portion of said second fraction in a volumetric ratio less than that which they were initially present in said catalytically reforming product, the resulting mixture having an octane rating in excess of about 98.0 and of which at least 45.0% by volume is distillable below a temperature of 212 -F., and combining the remainder of said first and second fractions with said third bottoms fraction to yield a high octane blending stock of which less than about 45.0% is distillable at a temperature below 212 F.

From the foregoing embodiments, it is readily ascertained that I have found a method to produce a motor fuel having characteristics far exceeding the rigid specifications imposed thereupon. The high octane, highly volatile gasoline of the present invention is prepared by fractionating a debutanized catalytically reformed product efliuent into three distinct fractions: (1) a pre-toluene fraction, (2) a toluene fraction, and (3) a posttoluene fraction. By combining the pre-toluene and toluene fractions in a volumetric ratio which is less than that in which they were initially present within the catalytically reformed product, there results a gasoline possessing the requisite high octane rating as well as the unusually high volatility factor, as measured by the volume percent thereof which is distillable at a temperature below 212 F. in accordance with Standard ASTM distillation methods. As stated in the foregoing embodiments, the remaining portions of the pre-toluene and toluene fractions may be recombined with the posttoluene fraction to yield a high octane blending stock suitable for utilization in the production of pool gasoline.

The means by which the detail fractionation is combined with a catalytic reforming process, is illustrated in the accompanying drawing. With reference to the drawing, it is noted that the present invention is readily separated into its component parts, a reaction section which encompasses a catalytic reforming unit, and a fractionation section. The charge stock, for example, a semiheavy naphtha having an initial boiling point of about 200 F. and an end boiling point of about 350 F. (by ASTM 100 ml. distillation), and having a relatively low octane rating, is passed through line 1 into heater 2, to be raised to the desired operating temperature. Prior to entering heater 2, the liquid charge is admixed with internally recycled hydrogen in line 3, in an amount to result in a hydrogen to hydrocarbon mol ratio within the range of from about 5.0 to about 20.0. The heated mixture, at a temperature within the range of about 800 F. to about 1100 F., passes through line 4 into reforming reactor 5 at a liquid hourly space velocity, defined as volumes of hydrocarbon charge per volume of catalyst disposed within the reaction zone, of about 0.5 to about 10.0. Reactor 5 is maintained under an imposed pressure within the range of about 300 to about 1500 pounds per square inch, and has disposed therein a suitable reforming catalyst comprising metals selected from the platinumgroup of the periodic table. Suitable reforming catalysts comprise platinum, palladium, osmium, iridium, ruthenium, rhodium, mixtures of two or more, etc, composited with a suitable refractory inorganic oxide carrier material. It is understood that the precise composition of the catalyst, and the concentrations of the various catalytically active metallic components, are not essential to the combination process of the present invention. Both the catalyst disposed in reactor 5, and the operating conditions imposed therein, are selected to result in a catalytioally reformed liquid product effiuent having an octane rating in excess of about 98.0, F-l Clear.

The total reactor 5 effluent is Withdrawn through line 6, passing into separator 7 from which a hydrogen-rich recycle gas stream is withdrawn through line 8 via com pressor 9, discharging through line 3 to be admixed with the fresh hydrocarbon charge in line 1. At least a pot"- tion of the recycle gas is withdrawn from the process through line 10 containing pressure control valve 11. Normally liquid hydrocarbons are Withdrawn from separator 7 through line 12, passing into stabilizer 13. The operating conditions imposed upon stabilizer 13 are such that the column may function as a debutanizer, the C to C hydrocarbons being withdrawn as an overhead gaseous product through line 14, or as a depropionizer, such that the butanes are retained in the bottoms fraction leaving via line 15, or to include any portion of the C hydrocar bons present in the reactor 5 efiiuent, in the debutanized liquid product leaving stabilizer 13 via line 15.

The catalytically reformed liquid product effluent is passed into toluene fractionator 16, containing center-well 17. The reformed product effluent is fractionated into three individual fractions; the first fraction, pro-toluene," is obtained as an overhead product in line 18 at a cutpoint less than about 90 C. and preferably within the range of about C. to C. The middle, toluene fraction is removed via line 20 from above center-Well 17, and is obtained at a cut-point less than 120 C. and preferably within the range of about C. to about C. The third fraction, or the post-toluene bottoms fraction, is removed from toluene fractionator 16 via line 22, and is substantially toluene-free. Both the pre-toluene and toluene fractions are transmitted to storage tanks 19 and 21 respectively, from which predetermined quantities are withdrawn via lines 23 and 24 respectively, combining in line 25 to yield a high octane (greater than 98.0 F-l Clear), highly volatile (45.0% by volume of which boils at a temperature below 212 F.) motor fuel gasoline. The remaining portions of the pre-toluene and toluene fractions are withdrawn from the storage tanks via lines 26 and 27 respectively, being combined with the post-toluene fraction in line 22 to yield a high octane blending stock suitable for utilization in pool gasoline.

The following example is given for the purpose of indicating the benefits to be afiorded through the utilization of the process of the present invention as hereinbefore described with reference to the accompanying drawing. The catalyst employed in the example was a composite of 5 -inch alumina spherical particles combined with 0.75% by weight of platinum, 0.35% by weight of chlorine and 0.35% by weight of fluorine. The catalyst was disposed in the reaction zone in three individual beds, having suitable internal heating elements therebetween. The reaction zone was maintained under an imposed hydrogen pressure of 500 pounds per square inch, and the 5 charge stock passed therethrough at a. liquid hourly space velocity of 1.0. The liquid charge was admixed with hydrogen in an amount to yield a hydrogen to hydrocarbon mole ratio of 10.0; the operating temperature of the catalyst disposed within the reaction zone was adjusted to yield a normally liquid product efiluent having an octane rau'ng in excess of about 100.0, F-l Clear. The operation was continued over a period of about 30 days until the catalyst life had attained a level of about 25.0 barrels per pound. The charge stock was a semi-heavy naphtha having an octane rating, F-l Clear, of 36.0, and of which less than 5.0% by volume was distillable at a temperature below 212 F. Various properties of the charge stock are given in the following Table I, along with the properties of the catalytically reformed efiiuent obtained as a composite sample from the entire period of operation.

TABLE I Properties of Charge Stock and Reformed Product Charge Product Gravity, API 60 F 59. 3 45. 4 100 Ml. ASTlVI Distillation, F.:

Initial Boiling Point 203 118 End Boiling Point 348 400 Vol. Percent 212 F 5. 38. Hydrocarbon Type Analysis, Vol. Percent:

Paraffins 71 Olefins 'Ir.

Naphthene 19 Aromatics 1 64. 0 Octane, Ratings:

F-l C ar 36. 0 100. 5

F-1+3 cc. TEL/gal 64. 8 2 103. 8

1 183 vol. Del-cent toluene. 2 1.5 cc. TEL/gal.

It should be noted, from the data presented in the foregoing Table I, that although the octane rating of the liquid product elfiuent is entirely satisfactory, being 100.5, the volatility requirement falls far short of the required specification, being only 38.5% distilled at a temperature of 212 F.

The catalytically reformed liquid product effluent was fractionated at cut-points of 885 C. and 116 C., to provide pre-toluene, toluene, and post-toluene fractions. The various properties of the pre-toluene and toluene fractions are given in the following Table II, along with the properties obtained upon the blended product.

TABLE II Properties of Blendmg Fractions and Blended Products Cut-point, C 88.5 116 Vol. Percent of Reformed Product 35. 4 18. 6 Aromatics, Vol. Percent 8.1 82.7 Toluene, Vol. Percent 1 0.9 70. 7 Vol. Percent in Blended Produc 23. 7 76. 3 Properties of Blended Product:

Gravity, APT 60 F 46.1 ASTM 100 Ml. Distillation, F.-

IBP 126 5% 10% 163 30% 187 50%. 207 70% 219 32):? 229 End Point 259 Vol. Percent 212 F 57. 5 Octane Ratings:

F-l Clear 100.5 F1+1.5 cc. TEL/gal 106.6 Aromatics, Vol. Percent 65.0 Toluene, Vol. Percent 54. 0

It should be noted that the fractions were blended in a volumetric ratio of 23.7 to 76.3, which is substantially less than the 35.4 to 18.6 ratio in which they were initial- 1y present in the reformed product. From the properties of the blended product, it is noted that the octane rating is substantially the same, being 100.5 F-l Clear, and that the response to tetra-ethyl lead has increased irom 103.8 to 106.6. However, it must also be noted that the volatility factor, that is, the volume percent distillable at a temperature below 212 F. has increased to 57.5, which figure far exceeds the minimum required.

The foregoing'specification and example clearly indicate the method of the present invention, and illustrate the benefits to be aiforded through the utilization thereof.

I claim as my invention:

1. A process for producing a gasoline having an F1 Clear octane rating in excess of about 98.0, at least 45 .0% by volume of which is distillable at a temperature below 212 R, which process comprises fractionating a debutanized catalytically reformed product of which less than 45.0% by volume is distillable at a temperature of 212 E, into a first fraction obtained at a cut-point within the range of about C. to about C. and substantially free from toluene, a second iraction obtained at a cutpoint within .the range of about C. to about C. and containing substantially all the toluene initially present in said debutan-ized reformed product, and a third bottoms fraction higher boiling than toluene; combining a portion of said first fraction with a portion of said second fraction in a volumetric patio less than that in which they were initially present in said catalytically reformed product and such that the resulting mixture has an octane rating, F-l Clear, greater than 98.0 and at least 45.0% by volume of which is distillable at 212 F, and combining the remainder of said first and second fractions with said third bottoms fraction to yield a high octane blending stock of which less than 45.0% by volume is distillable at a temperature of 212 F.

2. A combination process for producing high octane gasoline of which at least about 45 10% by volume is distillable at a temperature below 212 R, which comprises catalytically reforming a low octane hydrocarbon mixture of lower volatility, at reforming conditions selected to produce a liquid reformed product having an octane rating, F-l Clear, in excess of about 98.0, of which less than about 45 .0% by volume is distillable at a temperature of 212 F., fractionating said catalytically reformed product into a first fraction lower boiling than toluene and obtained at a cut-point less than about 90 C., a second toluene fraction obtained at a cut-point less than about 120 C. and a third bottoms fraction higher boiling than toluene; combining a portion of said first fraction with a portion of said second fraction in a volumetric ratio less than that in which they were initially present in said catalyti-cally reformed product and such as to yield a high octane mixture of which at least about 45 .0% by volume is dist-illable at a temperature below 212 F., and combining the remainder of said finst and second zfiractions with said third bottoms fraction to yield a high octane blending stock of lower volatility.

3. The process of claim 2 further characterized in that said first fraction is substantially free from toluene, and said second fraction contains substantially all the toluene initially present in said oatalytically reformed product.

4. The process of 2 further characterized in that said first fraction is obtained at a out-point within the range of about 85 to about 90 C., and said second fraction is obtained at a cut-point of irom about 110 C. to about 120 C. I

5. A combination process for producing a gasoline having an F1 Clear octane rating in excess of about 98.0, at least 45 .O% by volume of which is :distillable at a temperature of 212 R, which process comprises c-atalytically reforming a low-octane hydrocarbon mixture of lower volatility, at reforming conditions selected to produce a liquid reformed product having an octane rating, F-l Clear, in excess of about 98.0 of which less than 45.0% by volume is distillable at a temperature of 212 F., fractionating said reformed product into a first fraction, obtained at a cut-point within the range of about 85 C. to about 90 C. and substantially free from toluene, a second inaction obtained at a cut-point within the range of about 110 C. to about 120 C. and containing substantially all the toluene initially present in said reformed product, and a third bottoms fraction higher boiling than toluene; combining a portion of said first fraction with a portion of said second vfiraction in a volumetric ratio less than that in which there were initially present in said catalytically reformed product and such that the resulting mixture has an octane rating, F-l Clear, in excess-of about 98.0, of which at least 45.0% is distillable at 212 F., and com- References Cited in the file of this patent UNITED STATES PATENTS Sachanen et a1 Aug. 13, 1940 Hamilton Oct. 3, 1961 FOREIGN PATENTS 572,439 Canada Mar. 17, 1959

Claims (1)

1. A PROCESS FOR PRODUCING A GASOLINE HAVING AN F-1 CLEAR OCTANE RATING IN EXCESS OF ABOUT 98.0, AT LEAST 45.0% BY VOLUME OF WHICH IS DISTILLABLE AT A TEMPERATURE BELOW 212*F., WHICH PROCESS COMPRISES FRACTIONATING A DEBUTANIZED CATALYTICALLY REFORMED PRODUCT OF WHICH LESS THAN 45.0% BY VOLUME IS DISTILLABLE AT A TEMPERATURE OF 212* F., NTO A FIRST FRACTION OBTAINED AT A CUT-POINT WITHIN THE RANGE OF ABOUT 85*C. TO ABOUT 90*C. AND SUBSTANTIALLY FREE FROM TOLUENE, A SECOND FRACTION OBTAINED AT A CUTPOINT WITHIN THE RANGE OF ABOUT 110*C. TO ABOUT 120*C. AND CONTAINING SUBSTANTIALLY ALL THE TOLUENE INITIALLY PRESENT IN SAID DEBUTANIZED REFORMED PRODUCT, AND A THIRD BOTTOMS FRACTION HIGHER BOILING THAN TOLUENE; COMBINING A PORTION OF SAID FIRST FRACTION WITH A PORTION OF SAID SECOND FRACTION IN A VOLMETRIC RATIO LESS THAN THAT IN WHICH THEY WERE INITIALLY PRESENT IN SAID CATALYTICALLY REFORMED PRODUCT AND SUCH THAT THE RESULTING MIXTUE HAS AN OCTANE RATING, F-1 CLEAR, GREATER THAN 98./ AND AT LEAST 45.0% BY VOLUME OF WHICH IS DISTILLABLE AT 212*F., AND COMBINING THE REMAINDER OF SAID FIRST AND SECOND FRACTIONS WITH SAID THIRD BOTTOMS FRACTION TO YIELD A HIGH OCTANE BLENDING STOCK OF WHICH LESS THAN 45.0% BY VOLUME IS DISTILLABLE AT A TEMPERATURE OF 212*F.

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