US2944004A - Preparation of component for premium grade motor gasoline - Google Patents

Description

United States Patent PREPARATION OF COMPONENT FOR PREMIUM GRADE MOTOR GASOLINE Wilhelmus M. J. Ruedisnlj, The Hague, Netherlands, as-

signor to Shell Oil Company, a corporation of Dela ware No Drawing. Filed Oct. 26, 1955, Ser. No. 543,027 Claims priority, application Netherlands, Oct. 29, 1954 3 Claims. (Cl. 208-100) This invention relates to the preparation of a component for premium grade motor gasoline. More particularly, it relates to the preparation of such component through platforming.

The octane number of premium grade motor gasoline has gradually increased until at present it is approaching 100. In order for a material to serve in fairly large quantities as a component in premium grade motor gasoline it must now have an F-l octane number with 1.5 cc. TEL of at least 95. About the only material available in large quantities which meets this requirement is catalytically cracked gasoline. Other materials such as straight run gasoline and thermal gasoline can be used only in relatively small amounts along with costly blending agents such as alkylate, C polymer, aromatic extracts, and the like.

It is lcnown that most gasolines of low octane number may be much improved by catalytically reforming, and more especially by the special type of catalytic reforming called platforming, which is to say catalytic reforming in the presence of hydrogen under dehydrogenation conditions with an acidic platinum catalyst. The acidic platinum catalyst consist essentially of from .1 to 1% of platinum combined with an acidic support material such as an alumina containing combined fluorine and/or chlorine or a cracking catalyst such as the proprietor-y silica-alumina, silica-magnesia, silica-zirconia, aluminaboria, etc. cracking catalysts. The particular advantage of platforming over the older so-called hydroforming with catalysts promoted with compounds of such elements as molybdenum, chromium, cobalt, nickel, and tungsten is that in platforming a definite and controlled amount of selective hydrocracking is effected and isomerization reactions are catalyzed to a much greater degree.

Although the liquid product produced by such platforming treatment, called platformate, has a relatively high octane number, the situation has reached the point where even this product is frequently unsuited for use in any large concentration in premium grade motor gasoline. As a consequence, the refining industry is turning to the costly expedients of thermally reforming the platformate to further improve it and/or of subjecting the platformate to a liquid extraction treatment, e.g., so-called Rexforming.

It is known that in the case of certain other gasolines it is possible by subjecting them to very sharp fractionation to separate out narrow fractions of low octane number. The removal of such fractions would, of course, improve the remainder. This is disclosed, for example, in Patents Nos. US. 1,868,102 to Henderson et al. and US. 2,055,455 to Taylor et al. This expedient has not come into use for the reason that in order to separate low octane components from such materials it is necessary to separate very clean cut narrow fractions and while this can 'be done in efficient laboratory equipment it is impossible in the usual commercial fractionation equipment and impractical in the superfractionation equipment that would be required.

In copending application Serial No. 543,026, filed October 26, 1955, now US. Patent No. 2,874,114, it has been shown that in the particular case of platformates derived from selected fractions of naphthenic straight run gasolines it is possible to improve the properties by fractionating the stabilized platformate to remove that part boiling between and 105 C. This is a relatively broad range fraction which can be separated economically in the usual commercial fractional distillation columns. The separation of this fraction from this particular material is unique since the separation of the same fraction from straight-run gasoline, thermal gasolines, or catalytically cracked gasoline affords no improvement at all. The mentioned copending application is directed to the production of /130 grade aviation gasoline with fractionated plattorrnate.

It has been discovered that platformate of the motor gasoline boiling range may also be improved by fractionating out the material boiling between 80-85 and C. and that platformates may be therefore made more suitable for use in premium grade motor gasoline. However, for the case of motor gasoline it has been discovered that a better improvement may be obtained by fractionating out even a broader fraction boiling between 80-85 and l30-135 C. This is considered surprising since better results would be expected by considerably narrowing the fraction rather than broadening it, and also since no appreciable improvement is obtained by separating the same fraction from other gasolines such as straight run gasoline, thermally cracked or reformed gasoline, and catalytically cracked gasolines.

The process of the invention comprises platforming a straight-run gasoline or a substantial fraction thereof, fracti-onating the resulting liquid platformate to separate and remove that part boiling between 80-85 and 105 C., and preferably that part boiling between 80-85 and 130- 135 (2., said fractionating being carried out either before or after stabilizing the platformate, and blending back the platformate boiling below and above the separated fraction.

While either of the mentioned fractions may be advantageously removed it is to be pointed out that the same or similar results cannot be obtained by removing intermediate fractions. The cut point of about 105 C. is rather critical. For example, if a fraction boiling from 80-85 up to say 100 C. is separated the improvement is much less and the fractionation becomes much more diflicult and costly because of the reduced boiling range. On the other hand, if the range is increased only slightly to say 80-85 to C. hardly any improvement at all is obtained. Similarly with the broader range fraction, if the end point is raised to say 140 C. a poor result is obtained. One should therefore remove either the 80- 85 to 105 C. fraction or the 80-85 to 130-135 C. fraction and not, for example, an 80-85 to C. fraction or a 100 to C. fraction.

The process is applicable for the production of improved stocks from straight-run gasoline of either naphthenic or parafiinic nature but is particularly advantageous when the starting material is a straight-run highly paraffinic gasoline, i.e., one containing upwards of 55% by weight paraffins. It is therefore particularly useful with gasolines derived from Middle East crudes. When starting with such paraflinic gasolines the separation of the mentioned broader fraction is usually necessary whereas when starting with a naphthenic gasoline, i.e., having at least 40% by weight naphthenes, in most cases products with a sufiicicntly high octane number are already obtained when the material boiling between 80-85" C. and 105 C. is separated.

The boiling range of the straight-run material subjected to the platforming operation may cover the complete boiling range of motor gasoline. In most cases, however, it is found that there is no advantage in including that part of the straight-run gasoline boiling below 65 C. and it is therefore advisable to remove this material prior to the platforming operation. This light material may be then blended with the platformate. In many cases the straight-run material is topped to an even higher temperature in the range of 85 to about 100 C. although this is less preferred. The end point may be as high as 205 and 210 C. but is normally held around 200 C. or slightly below. The platformate produced upon platforming these materials normally boils over the full range of motor gasoline and has an ASTM distillation end point around 205 C. as it is or after re-running.

The platforming treatment is effected in the known way using an acidic platinum catalyst. The treatment is effected in the presence of added hydrogen for which purpose the hydrogen-rich gas formed in the process is conveniently recycled in part. The platforming is carried out at pressures between about 2 and 100 atmospheres and preferably between about 20 and 40 atmospheres since with higher pressures, particularly when operating at temperatures higher than 500 C., the yield of liquid product is reduced and the quality of the product as a component of motor gasoline also declines. The operation may be carried out at temperatures between approximately 450 C. and 550 0., preferably between 450 C. and 525 C.

Before the liquid platformate is fractionated to remove the mentioned fraction the propane and lighter hydrocarbons still present therein, and if desired the butane also, may be removed. This is effected in a stabilizing column, in the same manner as for other motor gasolines, from which column the propane and lighter components, and if desired also the butane, are withdrawn at the top and the stabilized platformate at the bottom. If desired, the stabilization can be carried out after the above-mentioned fractionation of the platformate to separate and remove the mentioned fraction.

The materials boiling below and above the separated fraction are combined. This material is essentially a full range gasoline, i.e., it has an ASTM initial boiling point and final boiling point in the usual range for motor gasoline. If the platforming operation is carried out under usual conditions it will be found to have a high octane number which with the addition of 1.5 cc. of TEL per US. gallon is 95 or higher. It is excellently suited for use in preparing motor gasolines of premium grade.

The process according to the invention is further illustrated by examples. The octane numbers referred to above and hereinafter are F1 octane numbers determined by ASTM method D90848T.

Example I A straight-run naphtha boiling from about 93 C. to 191 C. was separated from a straight-run gasoline derived from a Middle East crude. This was a parafiinic naphtha containing about 59.5% by weight of paramns. This naphtha was platformed by passing it in contact with a commercial platforming catalyst at a rate of 2.3 liters per liter of catalyst per hour together with hydrogen-rich recycled gas obtained from the process in a quantity corresponding to 8 mols of hydrogen per mol of naphtha at a temperature of 460-500 C. and a pressure of about 40 atmospheres.

After separating the hydrogen-rich gas phase which was recycled, the liquid platformate obtained in a yield of approximately 95% by weight, calculated on the naphtha introduced, was stabilized in a stabilizing column adjusted to remove the butane and lighter hydrocarbons. The stabilized platformate thus obtained had a clear octane number of 82.0 and after addition of 1.5

cc. TEL per US. gallon had an octane number of 91.2. This material was then fractionated using two fractionating columns having 30 trays each to separate first the material boiling up to about 82 C. and then material boiling up to about 132 C. The overhead product from the first column boiling up to about 82 C. and the bottom fraction from the second column boiling above 132 C. were then combined. This product had an octane number of 92.0 and, after addition of 1.5 cc. TEL per US. gallon, an octane number of 97.4. This product was an excellent component for premium grade motor gasoline whereas the platformate prior to the fractionation was unsuited except when used in small amounts in combination with costly blending agents.

The material removed by the fractionation which boiled between about 82 C. and 130 C. had, after addition of 1.5 cc. TEL per U.S. gallon, an octane number of 72.0.

It is to be emphasized that the removal of the mentioned fraction alfords a substantial improvement in the case of platformates produced as described but does not afford any substantial improvement if applied to other gasoline stocks such as straight-run gasoline, thermal gasolines, catalytically cracked gasoline. This is illustrated in the Examples II to IV which are submitted for comparison.

Example II A straight-run gasoline of about 200 C. end point obtained from Kirkuk crude had a clear octane number of 43.9 and, after addition of 1.5 cc. TEL per gallon, an octane number of 57.7. This gasoline was fractionated in the manner described (in fractionating columns having 30 plates) to separate in one case the material boiling between 85 and C. and in another case the material boiling between 85 and C. These separated fractions, after addition of 1.5 cc. TEL per gallon, and octane numbers of 68.7 and 60.6, respectively. It is thus seen that by removing either of the mentioned fractions from straight-run gasoline the quality of the remainder would be impaired rather than improved.

Example III A thermal gasoline having an end point of about 200 C. obtained by the thermal cracking of a mixture of East and West Texas crudes had a clear octane number of 73.0 and, after addition of 1.5 cc. TEL per gallon, an octane number of 81.1. This thermally cracked gasoline was likewise fractionated in the same fractionating columns to remove in one case the material boiling between 85l05 C. and in the other case the material boiling between 85130 C. The octane numbers of these removed fractions, after addition of 1.5 cc. TEL per gallon, were 86.7 and 83.4, respectively. It is therefore seen that also in the case of thermally cracked gasoline the removal of either of the mentioned fractions leaves a gasoline of impaired, rather than improved properties.

Example IV A catalytically cracked gasoline of about 200 C. end point obtained by the catalytic cracking of a Middle East crude had a clear octane number of 91.4 and, after addition of 1.5 cc. TEL per gallon, an octane number of 95.0. This catalytically cracked gasoline was likewise fractionated in the same fractionation columns to remove in one case the material boiling between 85 and 105 C. and in the other case the material boiling between 85 and 130 C. The separated fractions, after the addition of 1.5 cc. TEL per gallon, had octane numbers of 94.5 and 93.6 respectively. In this case an improvement results from the removal of the mentioned fractions. The improvement is however entirely too slight to be considered for practical application, particularly in view of the large loss of material which would result in this case. The maximum improvement would be less than 0.5 octane numbers at a loss of yield of over 25% by volume which is obviously no advantage.

Example V The same platformate produced as described in Example I was fractionated in the same fractionating column to remove material boiling between about 82 C. and 105 C. The fraction removed, after addition of 1.5 cc. TEL per gallon, had an octane number of 63.6. Considering that the corresponding octane number at the full range platforrnate was 91.2, it is evident that the removal of this fraction in the case of the platformate results in a very substantial improvement. The material removed in this case is only about 16% of the platformate.

I claim as my invention:

1. In a process for the preparation of a high octane number component for premium grade automotive gasoline which comprises catalytically reforming a straightrun naphtha boiling within the gasoline boiling range by contacting the naphtha with an acidic platinum catalyst at a temperature between 450 C. to 550 C. and a pressure between 2 and 100 atmospheres, the improvement comprising increasing the octane number of the reformate by separating and removing an intermediate fraction boiling between 85 C. and 130 C., recombining the fractions boiling below and above said intermediate fraction to produce thereby a premium grade automotive gasoline component having an F-l octane number with 6 1.5 cc. TEL per gallon of at least 95 and having approximately the initial boiling point and the final boiling point of automotive gasoline.

2. The process according to claim 1 wherein the straight-run naphtha is a fraction boiling between about C. and 200 C. and is obtained from a straight-run gasoline containing at least about 55% by weight paraifin's.

3. The process according to claim 1 wherein the straight-run naphtha is obtained from a straight-run gasline containing at least 40% by weight naphthenes and the intermediate fraction separated and removed from the catalytic reformate has a boiling range from C. to C.

References Cited in the file of this patent UNITED STATES PATENTS 2,593,561 Herbst et a1 Apr. 22, 1952 2,626,893 Morrow Jan. 27, 1953 2,684,325 Deanesly July 20, 1954 2,736,684 Tarnpoll Feb. 28, 1956 2,740,751 Haensel et al Apr. 3, 1956 OTHER REFERENCES Progress in Petroleum Technology, Am. Chem. Society, Washington, DC, page 365 (last paragraph) and page 370, Table XI, published Aug. 7, 1951.

Claims (1)

1. IN A PROCESS FOR THE PREPARATION OF A HIGH OCTANE NUMBER COMPONENT FOR PREMIUM GRADE AUTOMOTIVE GASOLINE WHICH COMPRISES CATAYLTICALLY REFORMING A STRAIGHTRUN NAPHTHA BOILING WITHIN THE GASOLINE BOILING RANGE BY CONTACTING THE NAPHTHA WITH AN ACIDIC PLATINUM CATALYST AT A TEMPERATURE BETWEEN 450*C. TO 550*C. AND A PRESSURE BETWEEN 2 AND 100 ATMOSPHERES, THE IMPROVEMENT COMPRISING INCREASING THE OCTANE NUMBER OF THE REFORMATE BY SEPARATING AND REMOVING AN INTERMEDIATE FRACTION BOILING BETWEEN 85*C. AND 130*C., RECOMBINING THE FRACTIONS BOILING BELOW AND ABOVE SAID INTERMEDIATE FRACTION TO PRODUCE THEREBY A PREMIUM GRADE AUTOMOTIVE GASOLINE COMPONENT HAVING AN F-1 OCTANE NUMBER WITH 1.5 CC. TEL PER GALLON OF AT LEAST 95 AND HAVING APPROXIMATELY THE INTITIAL BOILING POINT AND THE FINAL BOILING POINT OF AUTOMOTIVE GASOLINE