US3310485A - Hydrogenation of olefinic gasoline - Google Patents

Description

United States Patent 3,310,485 HYDROGENATION 0F OLEFINIC GASOLINE Paul G. Bercik, Gleushaw, and Alfred M. Henke, Springdale, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed May 4, 1964, Ser. No. 364,762 Claims. (Cl. 208143) Our invention relates to aprocess for hydrogenating olefinic containing light distillate stocks employing a hydrocracking catalyst.

In the operation of a refinery wherein a significant portion of the total gasoline pool is produced as light, fluid catalytically cracked (FCC) gasoline, it is quite often found that the octane sensitivity (Research Octane Number minus Motor Octane Number at the same level of TEL addition) of the gasoline pool is not sutficiently low to meet the increasingly more stringent demands of the market. As is known in the art, gasolines containing considerable quantities of olefinic hydrocarbons, such as, for example, light FCC gasolines, have poor octane sensitivity and it follows from this that blending such stocks into the refinery gasoline pool tends to increase the octane sensitivity of the total pool. To construct and maintain a hydrogenating unit and also to purchase and maintain large inventories of hydrogenating catalysts tailored to hydrogenate these stocks of high octane sensitivity in order to saturate the deleterious olefinic components is in most instances economically unfeasible or at least undesirable. To effect such hydrogenation quickly and with the least expense, it wouldappear advantageous to attempt the hydrogenation in an existing facility such as a hydrocracking unit employing a hydrocracking catalyst. It has been found, however, that such an operation ca-uses side reactions, mainly polymerization and alkylation, resulting in the production of heavy materials having final boiling points or endpoints significantly greater than the endpoint of the charge stock. Thus, the production of this heavy material not only raises the endpoint of the gasoline but also lowers the Research Octane Number of the gasoline at any given level of Motor Octane, and, as will be realized, any lowering of the Octane Number is, of

course, undesirable.

We have discovered a method whereby gasoline containing olefinic components can be hydrogenated in order to saturate, at least partially, such olefinic components tained until at least about 500 volumes of charge per volume of catalyst have been passed through the catalytic reaction zone. The temperature is then reduced to below 500 F. while the hydrogenation is continued.

Charge stocks suitable for employment in the process of our invention include petroleum distillates, particularly light distillate stocks, which contain any considerable amount of olefinic hydrocarbons. By considerable amount ismeant any petroleum distillate fraction con- .taining from about 25 to about 75 percent by volume olefinic constituents. The process of our invention is particularly suitable for the treatment of light FCC gasolines generally boiling from the C range up to about 350 F.

The hydrocracking catalysts which can be employed in our invention include any of the well-known two-component hydrocracking catalysts wherein a minor amount of a hydrogenating catalyst is composited with a major amount of a cracking catalyst, e.g., acidic hydrocracking catalysts. For example, such catalysts include the oxides and sulfides of the Group VI and the Group VIII metals either alone or in admixture distended on an acidic support. The acidic supports include, among others, silicaalumina, magnesia-alumina, silica-zirconia-alumina and the particular alumina made in accordance with the methods described in applications S.N. 118,240, now Patent No. 3,188,174; 118,241, now Patent No. 3,151,939, and 118,279, now Patent No. 3,151,940, of Kehl and Stewart, filed June 20, 1961, when combined with tungsten together with either nickel or palladium. Hydrocracking catalysts of this type are also suitable when promoted with a halogen. The hydrocracking catalysts employed in our invention can also be either fresh catalysts or can be catalysts which have previously been employed in hydrocracking operations and then regenerated.

As mentioned above, the initial operating temperature employed in the process of our invention must be above about 500 F. and this initial operating temperature can be as high as about 675 F. Preferably, however, the initial operating temperature is maintained in a range from about 500 F. to about 575 F. After a throughput period of at least 500 volumes of charge per volume of catalyst, the operating temperature is then reduced to a level below 500 F. and can be reduced to as low as about 300 F. The actual range to which the operating temperature is reduced is, of course, determined by the extent of hydrogenation which it is desired to be effected. Generally, however, we find that the operating temperature can in most instances be reduced to a range from about 375 F. to about 450 F.

The hydrogen partial pressure employed during the initial period of operation in accordance with our process is in the range from about to about 3000 p.s.i.g. and preferably is from about 300 to about 1000 p.s.i.g. It should be pointed out that a certain decrease in production of the heavy materials during the period of initial operation can also be effected by increasing the hydrogen partial pressure. The extent of this reduction in heavy materials produced, however, is not nearly so great as that eifected with employment of temperatures above 500 F.

The space velocity employed during the initial period of the process of our invention can be from about 0.25 to 10 and preferably is from about 0.5 to about 4. We have also found that a hydrogen feed rate from about 1000 to about 10,000 standard cubic feet per barrel (s.c.f./b.), and preferably from 3000 to 6000 s.c.f./b. can be employed.

All of the above operating conditions are those which can be employed during the initial period of operation, i.e., until at least 500 volumes of charge per volume of catalyst have been passed through the reaction zone. After this initial period and when the operating temperature is reduced below 500 F. the other operating conditions can be varied to more conventional ranges.

In order to illustrate our invention in greater detail, reference is made to the following examples.

Example I In this example a light FCC gasoline having a 330 F. endpoint was hydrogenated over a fixed bed of a fresh, presulfided catalyst. The catalyst comprised 19.2% by weight tungsten, 6.4% by weight nickel and 2.0% by weight fluorine supported on American Cyanamid Triple A silica-alumina (25% A1 0 A series of runs were made employing temperatures in the range from below to just above 500 F. and a hydrogen partial pressure of either 500 or 1000 p.s.i.g. In all of the runs a LHSV 3 of 1.0 and a hydrogen feed rate of about 4000 s.c.f./b. were employed. The particular temperature and pressure employed in each run together with throughout rate and inspections of the charge and products are shown not an important factor in the early stages of hydrogenation with a hydrocracking catalyst at temperatures greater than 500 F. in accordance with our invention. In run 5 the temperature and pressure employed were the same in Table I below. 5 as employed in run 2, and yet the yield of heavy material TABLE I Run No. Charge Temperature, F 433 524 429 527 526 Pressure, p si 2' 500 500 1,000 1,000 500 Throughput, vl./vol l6. 36. 5 48.0 63.0 82.0

Liquid Product:

Recovery, percent by wt 95. 3 99. 4 94. 3 97. 6 97. 9

API Gravity 66.8 68.2 70.6 69.9 72.3 71.4

Aromatics, percent by vol 9. 9 7. 3 6.8 6.9 3. 7 6. 6

Olefins, percent by vol 57. 7 0. 5 0.4 0. 5 0.3 0.4

Bromine Number 100. 7 Nil Nil Nil Nil Nil Knock Rating, +2 cc. TEL:

Motor 83.5 86. 6 86.1 86. 3 s9. 2 Research 98. 2 86.9 86. 6 2 83. 6 90. 0 Distillation, ASTM D-86 Endpoint 330 455 352 407 318 360 Percent Charge Endpoint i 0.6 7.9 2.0 4.4 0.6 2. 5

1 Residue remaining after endpoint was recorded.

2 Appears low.

From the above table it can be seen that essentially all in run 5 after 82 volumes per volume throughout was the olefins of the charge stock were hydrogenated in each substantially the same as in run 2 after only 36.5 volof the runs; however, it can also be seen that in addiumes per volume of throughput. tion to the hydrogenation of the Ol fins, some side reac- The elfect of operating in accordance with the process tion occurred in almost each run as indicated by an inof our invention can be further seen by comparing the crease in the endpoint of the liquid product in the ASTM octane ratings of the gasolines from runs 1 and 3 with D-86 distillation test. It will be noted that the end the octane rating of the gasoline from run 5. Each of point of the light FCC gasoline charge stock is 330 F. these three gasolines contained about 7% aromatics and and any material in the products boiling above this figure yet th 360 F. endpoint gasoline from run 5 has a Reas shown y the 90%, 95% and endpoint Values theresearch and Motor Octane Number advantage of about 3 fore, evidence of heavy material produced by side reacover the gasolines from runs 1 and 3 having 445 F. and tions. (The percentage of this material produced is in- 407 F. endpoints, respectively. dicated in the last entry in each column.)

By a comparison of the data from runs 1 and 2, the Example 11 effect of employing a temperature above 500 F. can readily be seen. Thus, in run 1 at 433 F. and 500 In this example a light FCC gasoline having a p.s.i.g., about 8% of the liquid produced boiled above endpoint Was hydrogenated Over a fixed bed of a the endpoint of the charge stock; whereas in run 2 at generated, fluorine Promoted niekel'tuhgsteh on silica 524 F. and 500 p.s.i.g. only 2% of the liquid product alumina catalyst. This particular catalyst had been emboiled above the endpoint of the charge stock. More- P y for a substantial Period of time in Various hydro over, in run 1 the 90% point was 53 F. greater, the cracking operations and had substantially the same com- 95 point was 96 F. greater and the endpoint 125 F. Position as the fresh Catalyst p y in Example I greater than the corresponding distillation points for the With the exception of a somewhat lower fluorine contentcharge stock, while in run 2 the 90% and 95% distilla- The catalyst of this example Compiised 187% y Weight tion points of the hydrogenating gasoline product were tungsten, 64% y Weight nickel and 15% by Weight nearly the same as that of the charge stock and the endfluorine supported on American cyahamid Triple A point of the product was only 22 F. greater than the endsiiiee'ahlmina 2 s)- The egeheratioh P point of the charge, dure employed consisted of a carbon burnolf stage and A comparison of the product data from runs 1 and 3 55 a sulfiding stage. In the carbon burnofi stage nitrogen wherein the temperatures employed were substantially containing about 01% OXYgefl was Passed through the the same and below 500 F. a certain reduction in the Catalyst at a bed temperature of The Oxygen quantity of heavy materials produced was effe t d b i content was gradually increased to 2.0% while maintaincreasing the hydrogen partial pressure from 500 p.s.i.g. in g the bed temperature in the range from between run 1 to 1000 p.s.i.g. in run 3. Thus, the yield of heavy and 950 F. When 2.0% oxygen content was reached material was 4.4% at 1000 .i.g i ru 3 compared without further increase in bed temperature, air was gradwith 7.9% at 500 p.s.i.g. in run 1. However, when the lly added for a period of about 2 hours to complete pressure was held at 1000 p.s.i.g. and the temperature the Carbon hhfl'loii- This regenerated catalyst Was then increased to 527 F, (greater than 500 F,) i u 4, sulfided prior to its use in the runs of this example by the quantity of heavy material decreased to somewhat Contacting it with a hydrogen stream containing about less than 0.6%, almost identical to the charge stock. 10% hydrog n Sulfid a a catalyst bed t mperature of Furthermore, the boiling range of the liquid product in a ut 600 F-f r a ll 6 hours. run 4 was substantially the same as that of the charge A series of runs were made employing this regenerated stock. It can be seen, therefore, that increasing the prespresulfided catalyst employing temperatures in the range sure in combination with the employment of a temperafrom below to above 500 F., a hydrogen partial presture above 500 F. is extremely eifective in preventing sure of 500 p.s.i.g., a hydrogen feed rate of about 4000 the production of heavy material during the initial period s.c.f./b. and a space velocity of either 1.0 or 2.0. The of operation. particular temperature and space velocity employed in By a comparison of the data of run 5 with the data each run together with the throughput rate and inspections of run 2, it can be seen that the effect of throughput is of the charge and products are shown in Table II below.

TABLE II Run No. Charge Temperature, F 425 510 460 422 576 457 Space Velocity (LHSV), vol lhr /vol 2. 2. 0 2. 0 1. 0 1. 0 1. 0 Throughput, v0l./vol 17.0 106 533. 6 84 212.8 499. Liquid Product:

Recovery, percent by wt 98. 7 99. 4 97. 8 98. 3 92. 3 102. 7 API Gravity 70. 3 75. 6 73. 7 73. 2 76. 7 76.1 Aromatics, percent by vol 4.8 7. 8 3. 6 4. 0 5.0 3. 7 Olefins, percent by vol. 59. 7 2. 2 35. 9 21. l 0.9 15.1 Bromine Number 112. 7 38. 1 11.0 61. 6 37 1.72 27. 4 Knock Rating, +2 cc TE Motor 84. 0 86. 4 89. 5 85. 6 86. 7 89. 4 87. 7 Research 99. 2 94. 3 89. 5 97. 9 93. 5 90. 4 95.4 Distillation, D-86:

205 384 218 206 243 212 208 223 477 250 224 388 254 228 p 239 491 393 254 393 294 247 Percent Charge Endpoint.-- 1 0.6 18.3 6. 2 2. 4 8. 6 4. 4 2. 0

1 Residue remaining after endpoint was recorded.

The advantage in employing a temperature greater than 500 F. during the initial period of operation in order to avoid the production of heavy material can again be seen by comparing run 1 at 425 F. with run 2 at 510 F. Aside from temperature, the operating conditions in both of these runs were substantially the same and yet the amount of heavy material obtained in run 1 was 18.3% as opposed to 6.2% obtained in run 2a 300% improvement. The greater quantity of heavy material present in the product in run 1 is further emphasized by a comparison of the ASTM D-86 distillations.

A comparison of the data from runs 2 and 3 clearly demonstrates that after a throughput of greater than 500 volumes per volume a reactor temperature greater than 500 F. is not necessary to prevent the formation of heavy materials. Thus, in run 3 operating at 460 F. after 533.6 volumes per volume of throughput the amount of heavy material obtained was only 2.4%, while it was necessary in run 2 to operate at a temperature above 500 F. in order to reduce the formation of heavy material to 6.2%. This data confirms that the formation of heavy material is not a problem at temperatures lower than 5 00 F. after the catalyst has aged for the minimum period of 500 volumes per volume in accordance with our invention.

Runs 4, 5 and 6, wherein a space velocity of 1.0 rather than 2.0 was employed, are cumulative to the showing of runs 1, 2 and 3. Thus, in run 5 at 576 F. only about one-half as much heavy material was formed as in run 4 at 422 F. Further, run 6 again demonstrates that after a throughput of 500 volumes per volume a temper ature below 500 F., i.e., 457 F., can be employed to obtain only 2.0% of heavy material in the product.

Example III In this example the refinery gasoline pool, which inter alia contained the total refinery output of light FCC gasoline, varied in octane sensitivity in the range of 10 to 10.5. In order to reduce the octane sensitivity of the total pool down to an acceptable level, the fraction of the light FCC gasoline boiling from C to about 260280 F. endpoint was selected for hydrogenation in accordance with the process of our invention. This particular fraction was selected since it constituted the larger component of the gasoline pool and also contained a considerable amount of olefinic hydrocarbons (about 58%). The catalyst employed was an aged, presulfided nickel-tungsten promoted with 2% fluorine supported on alumina catalyst similar to the catalysts of Examples I and II. The hydrogenation was carried out at a temperature above 500 F. in an existing hydrocracking unit over the hydrocracking catalyst described above, which is normally contained in such unit. The hydrogenated FCC gasoline obtained from this hydrogenation was added to the refinery gasoline pool and the octane sensitivity of the pool, now containing the hydrogenated FCC gasoline, was reduced to 9.0.

We claim:

1. A process for hydrogenating a gasoline containing olefinic components which comprises contacting the gasoline with hydrogen in the presence of a hydrocracking catalyst under hydrogenating conditions of pressure, space velocity and hydrogen feed rate and at an initial temperature above about 500 F., maintaining the temperature above 500 F. until the catalyst has been contacted by at least 500 volumes of gasoline per volume of catalyst, then reducing the temperature to below about 460 F. while continuing the hydrogenation.

2. A process for hydrogenating a light fluid catalytically cracked gasoline fraction containing olefinic components, which process comprises contacting the gasoline with hydrogen in the presence of a hydrocracking catalyst comprising a minor amount of a hydrogenating compo nent composited with a major amount of an acidic hydrocracking component at an initial temperature above about 500 F., a hydrogen partial pressure from about to about 3000 p.s.i.g., a liquid hourly space velocity from about 0.25 to about 10 volumes of gasoline per volume of catalyst per hour and a hydrogen feed rate from about 1000 to about 10,000 s.c.f./b., maintaining these operating conditions until the catalyst has been contacted by at least 500 volumes of gasoline per volume of catalyst, and then reducing the temperature to below about 460 F. while continuing the hydrogenation.

3. The process of claim 2 wherein the fluid catalytically cracked gasoline fraction boils from the C range up to about 350 F.

4. The process of claim 2 wherein the hydrogen partial pressure is from about 300 to about 1000 p.s.i.g., the liquid hourly space velocity is from about 0.5 to 4 and the hydrogen feed rate is from about 3000 to about 6000 s.c.f./b.

5. The process of claim 4 wherein the hydrogenating component comprises nickel and tungsten and the hydrocracking component comprises silica-alumina.

6. The process of claim 5 wherein the catalyst is promoted with fluorine.

7. A process for hydrogenating a light fluid catalytical ly cracked gasoline fraction containing olefinic components, which process comprises contacting the gasoline with hydrogen in the presence of a hydrocracking catalyst comprising a minor amount of a hydrogenating component composited with a major amount of an acidic hydrocracking component at an initial temperature of from about 500 F. to about 675 F., a hydrogen partial pressure from about 100 to about 3000 p.s.i.g., a liquid hourly space velocity from about 0.25 to about 10 volumes of gasoline per volume of catalyst per hour and a hydrogen feed rate from about 1000 to about 10,000 s.c.f./b., maintaining these operating conditions until the catalyst has been contacted by at least 500 volumes of gasoline per '7 volume of catalyst, and then reducing the temperature to below about 460 F. and above about 300 F. while continuing the hydrogenation.

8. The process of claim 7 wherein the initial temperature is from about 500 F. to about 575 F., the hydrogen partial pressure is from about 300 to about 1000 p.s.i.g., the liquid hourly space velocity is from about 0.5 to about 4, the hydrogen feed rate is'from about 3000 to about 6000 s.c.f./b., and after the catalyst has been contacted by at least 500 volumes of gasoline per volume of catalyst, the temperature is then reduced to the range from about 375 F. to about 450 F.

9. The process of claim 8 wherein the hydrogenating 8 component comprises nickel and tungsten and the hydro cracking component comprises silica-alumina.

10. The process of claim 9 wherein the catalyst is promoted with fluorine.

References Cited by the Examiner UNITED STATES PATENTS 3,125,505 4/1964 Tupman et al. 208-143 3,169,106 2/1965 Lefrancois et a1 208-143 3,203,891 8/1965 Holden 208-143 DELBERT E. GANTZ, Primary Examiner.

S. P. I ONES, Assistant Examiner.

Claims (1)

1. A PROCESS FOR HYDROGENATING A GASOLINE CONTAINING OLEFINIC COMPONENTS WHICH COMPRISES CONTACTING THE GASOLINE WITH HYDROGEN IN THE PRESENCE OF A HYDROCRACKING CATALYST UNDER HYDROGENATING CONDITIONS OF PRESSURE, SPACE VELOCITY AND HYDROGEN FEED RATE AND AT AN INITIAL TEMPERATURE ABOVE ABOUT 500*F., MAINTAINING THE TEMPERATURE ABOVE 500*F. UNTIL THE CATALYST HAS BEEN CONTACTED BY AT LEAST 500 VOLUMES OF GASOLINE PER VOLUME OF CATALYST, THEN REDUCING THE TEMPERATURE TO BELOW ABOUT 460*F. WHILE CONTINUING THE HYDROGENATION.