US3125509A - Process for the treatment of petroleum - Google Patents

Description

United States Patent p 3,125,509 PROCESS FOR THE TREATMENT OF PETROLEUM DISTILLATES Bernard Laine and Charles Vernet, Lavera par Martigues, Bouches-du-Rhone, France, assignors to The British Petroleum Company Limited, London, England, a British joint-stock corporation No Drawing. Filed Oct. 26, 1960, Ser. No. 64,986 Claims priority, application France Oct. 26, 1959 11 Claims. (Cl. 208-264) This invention relates to the treatment of distillate petroleum fractions boiling above 150 C. and particularly to the treatment of distillates boiling between 150 and 450 such as 150-250 C., 25 0350 C. and 350450 C. distillates, and the the principal object of the invention is to provide a process by means of which the pour point and cloud point of such fractions may be substantially lowered.

According to the process of the present invention, the distillate is contacted in the presence of hydrogen with a catalyst having dehydrogenating and/ or cracking activity and comprising a silica-alumina base, at a temperature of at least 400 C. but below the temperature at which substantial cracking occurs, a pressure of at least 100 p.s.i.g., and a space velocity of the liquid feedstock not exceeding 30 v./v./hr., the temperature and space velocity being correlated so that the pour point of the stabilized distillate is at least 5 C. lower than the pour point of the feedstock.

For the purposes of the present specification, substantial cracking is understood to occur when more than 20% wt. of the feedstock is converted to material boiling below 150 C. Preferably not more than 15% wt. of the feedstock is converted to material boiling below 150 C. The temperature employed will not usually exceed 480 C. and in general the lower the temperature, the lower the space velocity.

The pressure employed will normally be between 100 and 1500 p.s.i.g. and the hydrogen to hydrocarbon mole ratio will normally be from 5 to 1 to 20 to 1.

In general, it is preferred to operate under conditions which result in an overall consumption of hydrogen, since such method of operation increases catalyt life, and to achieve such overall consumption of hydrogen it is necessary to operate at a pressure above the equilibrium pressure of the feedstock, i.e. the pressure obtainable by recycling the hydrogen produced at a particular combination of temperature and space velocity, no extraneous hydrogen being added after start-up.

A further advantage of operating with an overall consumption of hydrogen is that a reduction of the diesel index is minimized or avoided.

In some cases, however, it may be desired to reduce the pour point of the distillate without substantially reducing its specific gravity, and in these cases it is necessary to operate under conditions in which no hydrogen is consumed, i.e. at or below the equilibrium pressure as defined above.

Hydrogen may be added on a once-through basis, or it may be recycled.

The distillate fraction used as feedstock may have a low initial sulfur content, for example 0.1% wt. sulfur or less. Such low sulfur feedstocks may be straight-run materials or the products of previous refining treatments, for example, products of a hydrocatalytic desulfurization process. With'feedstocks containing higher amounts of sulfur, the process according to the invention may result in aconsiderable reduction in the sulfur content. In the case of feedstocks having a low initial sulfur content, the process may be accompanied by an increase in specific gravity.

35,125,509 Patented Mar. 17, 1964 Some lower boiling material will be produced by, for example, dehydrogenation, desulfurization and/ or a small amount of cracking, and this is separated from the product, preferably by fractionation, to stabilize it and give a material of the required boiling range and flash point. A convenient cut point is in the region of 170 C.

Particularly effective catalysts for the purposes of the present invention consist of molybdenum trioxide, M00 supported on a silica/alumina base, and a mixture of molybdenum trioxide, M00 and cobalt oxide, CoO, supported on a silica/alumina base.

It has been found that the presence of cobalt oxide, C00, is not necessary for achieving the desired reduction of the pour point but is essential if simultaneous desulfurization of the feedstock is required. Thus, in treating a sulfur-free feedstock or in treating a sulfur-containing feedstock when it is not necessary to remove sulfur, a particularly effective catalyst may have the following composition by wt.

Percent Molybdenum trioxide, M00 5-15 Silica, SiO 5-l4 Alumina Balance When it is desired to desulfurize the feedstock as well as reduce its pour point, the catalyst may have the following composition by weight:

Percent Molybdenum trioxide, MoO 5-15 Cobalt oxide, CoO .2-1 Silica, Si0 514 Alumina Balance The optimum content of molybdenum trioxide appears to-be Ill-11% and the optimum molar ratio of the metals Co to M0 appears to be .1.

The ratio of cobalt to molybdenum necessary to produce the desired reduction in the sulfur content is considerably less than in the case of conventional cobalt molybdate catalysts used for desulfurization. This may be due to the fact that more severe process conditions, i.e. higher temperature and pressure and lower space velocity, are required to produce the desired reduction in the pour point.

it has been found that the use of a catalyst having a silica/ alumina base enables a particular reduction in pour point to be effected at a lower temperature than is possible with a catalyst supported on an alumina base. The use of lower temperatures means that it is possible to use a lower hydrogen to hydrocarbon ratio, thereby reducing the cost of the process.

Experiments were carried out with four catalysts having the following compositions by weight.

On a base consisting of silica-free alumina.

These catalysts were used to treat a gas oil having a sp. gr. of 0.850 and a pour point of -1 C. under the following conditions.

'3 it) Temperature (catalysts Nos. 1

and 2) 420, 440 and 450 C. Pressure (catalyst No. 3),

40 kg./cm. 420, 450 and 480 C. Space velocity 1 v./v./hr.

Hydrogen to hydrocarbon ratio 10/ 1.

In order to maintain the hydrogen partial pressure at the desired level, it is necessary progressively to increase the total pressure since the reaction produces gas and consumes hydrogen.

Satisfactory operation over a period of 600 hours has been achieved on the light gas oil at a constant total pressure of 780 p.s.i. since, as the hydrogen consumption was small, the hydrogen partial pressure fell only from 570 to 500 p.s.i.

On the other hand, when treating the heavy gas oil at a fixed total pressure of 1000 p.s.i., the hydrogen partial pressure fell from 800 p.s.i. to 550 p.s.i. after 420 hours and pour conversion was then obtained at 460 C. Improved operation may be achieved by maintaining the 7 hydrogen partial pressure at 800 p.s.i. by progressively Table 1 Temperature, C 420 440 450 480 Catalyst No 1 2 3 1 2 1 2 3 3 Feedstock Specific Gravity at 15 C 0.850 O. 829 0.829 0. 835 0. 827 0. 827 0. 820 0.825 0. 824 0. 816 Pour Pint, C. l 13 16 7 -22 -22 -22 -22 22 Cloud Point, (1. 7 7 3 14 21 19 19 Total Sulfur, Percent Wt. 1. 2 0. O01 0. 001 0. 001 0. 001 0. 001 0. 001 0. 001 0. 001 0. 001 Distillation, 0.:

1 Method AFNOR N.F.T 60.105. 2 Method AFNOR N.F.T. 60.105. 3 Method AFNOR N.F.M. 07.009.

The catalyst may be employed as a fixed bed, a moving bed, or in the fluidized state.

The degree of reduction in pour point is a function of the catalyst activity and in the case of a fixed bed process, in which the catalyst is not continuously regenerated, the greatest reduction in pour point is obtained during the early stages of a processing period. In such circumstances, the operating temperature may be gradually increased to compensate for loss of activity. Alternatively, continuous catalyst regeneration may be employed, using either a moving or fluidized catalyst bed process.

If desired, a part only of a particular distillate may be treated by the process according to the invention and the resulting product blended with the untreated portion of the distillate to give a final product of reduced pour point.

It has been discovered that it is desirable to maintain a certain hydrogen partial pressure for any particular feedstock and that the degree of conversion falls off if the hydrogen partial pressure falls below this minimum even if the total pressure is maintained. The optimum values for the hydrogen partial pressure and the hydrogen to hydrocarbon ratio depend upon the nature of the feedstock. For example, these conditions are compared in the following table, No. 2, for a light gas oil having an I.B.P. of 220 C., an F.B.P. of 400 C. and a pour point of 1 C. and a heavy gas oil having an I.B.P. of 290 C., an F.B.P. of 390 C., and a pour point of +17 C.

Table 2 Partial "H /IL, Ratio Pressure of increasing the total pressure and this effect is illustrated by the results set out in Table No. 3.

Satisfactory treatment of a heavy gas oil at constant pressure may be achieved by adding between 20 and by volume of a lower boiling distillate such as kerosine to the heavy gas oil. An example of this method of operation is illustrated by the results set out in Table No. 4.

A silica-alumina base suitable for preparing a catalyst for use in accordance with the present invention may be made in a variety of ways.

According to one method, the silica gel is precipitated in situ in the pores of the alumina by hydrolyzing a silicon compound with which the alumina is impregnated. The silicon compound may be organic or inorganic and suitable compounds include ethyl silicate, trichlorosilane and tetrasilane. It is advantageous to add to the ethyl silicate, for example, a sufficient quantity of alcohol to saturate the alumina almost completely to ensure homogeneous distribution of the silicate in the alumina. Ethyl, methyl and other alcohols may be used for this purpose. Finally, the silicate is hydrolyzed by means of acidified water and the formation of the gel assisted by the addition of ammoniacal water. The silica-alumina composite is then dried and calcined. The following is a specific example of preparing a silica-alumina base by this method:

EXAMPLE In order to obtain 1,110 g. of a support having 10% silica, a solution was prepared containing 330 g. of ethyl silicate (30% SiO and cc. of methanol. 1 kg. of alumina granules calcined between 200 and 800 C. were slowly wetted with this solution while stirring and after several minutes to allow homogeneous impregnation, the granules were washed with 100 cc. of water containing 10% HCl. After several hours, the granules were washed with 100 cc. of ammoniacal water and then calcined at about 450 C.

'Table 3 [Catalyst AA3: S102 8.9%, M003 10.64%, C 0.55%, 2 Hydrogen Partial Pressure, 55 kgJomfl; Space Velocity, 1 v./v./hr.

Operating Conditions Hydrogen/Hydrocarbon Ratio=10l1 moles/mole Temperatures, C 430 440 456 Pressure, kgjcm. 73 73 73 74 74 76 77. 5 77.5 80 82 82 HOS 32 56 80 104 123 152 176 206 224 243 272 296 Feedstock Heavy Gas Oil Density at 15 0 881 342 342 342 343 844 346 349 846 347 347 347 343 Pour Point, 0--.. +17 +8 +8 +5 +5 +5 +3 +11 +5 +5 +5 +3 +5 016110 Point, 0---- +24 +11 +11 +9 +9 +10 +13 +15 +9 +9 +11 +11 +11 Paraflins, Percent wt. 13. 3 9. 7 Distillations ASTM, 0

1.13.1 273 136 143 139 136 142 136 134 145 145 133 137 145 5%." 312 162 180 176 176 135 177 179 135 135 130 174 133 56%. 375 332 333 324 317 236 326 331 325 325 326 321 327 90%. 400 394 406 332 374 390 332 396 336 337 336 393- 333 95%. 460 397 333 395 399 19.133-.-" 400 400 400 406 406 400 466 400 406 400 460 460 466 Yield, Percent w Gas 0 92.5 91.9 39.7 90.8 91.4 92.7 91.3 39.3 33.7 89.6 90.6 96.4 Gasoline 1.3 2. 3.2 2.1 2 1.9 2.7 4.4 2.9 2.7 2.3 H, Consumption, set/16161 224 236 245 232 212 232 274 264 246 234 206 266 Table 4 A more economic method of preparing a suitable silicaloamyst M3 (See Table 3)] alumina base consists in extruding an intimate mixture of silica gel and alumma. The silica may be prepared Operating Conditions.

Pressure 76 kgjcmfi 1n known manner from sod1um sllrcate and 1s washed with Space Velocity 1 v./v. hr. Ratio 01112110 Hydr0carbon=12/1 moles/mole sulfur acid to remove sod1um. The silica gel is then Temperature, 440 0. mixed with the alumina and the mixture extruded to form extrudates of between 2 and 2.75 mm. diameter. Two HOS Kero- Heavy Mix- 32 56 particularly effective catalysts prepared in this way had me Gas 011 me the following percentage compositions by weight.

Density at 15 0 792 375 359 334 333 Pour Point, o C +20 +15 35 Catalyst 1 Catalyst?! Cloud Point, C... +22 +18 6 +5 Distillation ASTM, 0.: 8.9 13.3 I,B,P 184 222 194 145 147 0 7 1 7 32 31 a 32 015 211 466 399 367 364 balance balance 216 380 373 233 466 466 339 390 Various results obtained using catalysts having bases prepared in the manner just described are set out in Mixture: 32.7 33 .7 Tables 6, 7 and 8. 28% 1 ,3: gggffg on 3g 6 It is important for the temperature and space velocity to be correctly correlated if a satisfactory reduction in The results obtained on treating a heavy gas oil using catalysts having bases prepared by the method just described are set out in Table 5. This table also illustrates the eifect of varying the silica content of the base. It will be seen that the results obtained with a 20% silica base are markedly inferior to those obtined with a 15% silica base and in general it has been found that the content of silica should not exceed 14% by weight of the total catalyst. 90% alumina.

Table 5 Operating Conditions: Hydrogen to Hydrocarbon ratio=7.5:1; Pressure, 1000 p.s.i.g.; Space Velocity, 1 v./v./hr. Cataly L68 1135, 20% Sili- L68 A22, 15% Silica in Base L58 A17, 10% Silica in Base ea in Base Temperatures, C 420 430 440 420 425 430 420 l 425 430 Feedstock Density at 15 C 869 828 823 823 826 825 827 826 829 Pour Point, C... +11 +2 1 --4 4 4 1 1 Cloud Point, O +13 +5 1 0 1 0 +2 0 +1 Parafiins, Percent wt... 13.8 8.5 9.1 10. 7 Distillations ASTM,

PI 248 70 70 70 70 70 70 5% 297 125 125 109 130 130 131 50% 352 323 314 314 323 322 32 1 388 367 369 373 377 376 375 400 374 385 389 394 392 399 P F 1 '400 376 392 395 398 394 399 Yield, Percent wt 96 96 98 99 98 99 The above catalysts had the following composition:

L68 11.35: 17.7% S10 10.64% M003, 0.55% 000, 71.11% A L68 11.22: 133% S102, 10.64% M003, 0.55% COO, 75.51% A190 11.68 14.17: 8.9% S102, 10.64% M003, 0.55% 000, 79.91% A 7 8 Table 6 Operating Conditions: Pressure, 40 kg./e1n. Space Velocity, 1 v./v./l1r.; Hydrogen to Hydrocarbon ratio, 7.5:1; Platiormer Hydrogen Catalyst L68 A37, 5% Silica in Base L.68 11.38, Silica in Base Temperatures, C 400 420 430 400 420 430 Density /4, C 816 811 809 Pour Point, C... 10 22 -22 Cloud Point, C 4 l5 l8 Distillation, C:

I.B.P 70 70 5%-. 205 130 282 270 90%. 342 334 95%". 357 357 F.B. 371 360 Yield, Percent wt 99 98 Catalyst composition:

L.68 A37: 4.4% SiOz, 10.64% M003, 0.55% C00, 84.41% A1203. L68 A38: 8.9% S102, 10.64% M00 0.55% 000, 79.91% A1203.

Table 7 [Catalyst A.44: 8.9% SiOz, 10.64% M003, 0.55% 000, 79.91% A1 03] Operating Conditions: 8.9% Silica as gel;

Hydrogen to Hydrocarbon rzlitioi 771511; 79.9% wt. Alumina, 10.7% wt v. v. r.

Pressure, kgn/crn.

Temperature, C

Table 8 Operating Conditions: Pressure, 70 kgjcnlfl; Space Velocity, 1 v./v./hr.; Hydrogen to Hydrocarbon ratio, 7.5:1 Catalyst L68 A.5l, 2 111m., 15% Mieroporous Silica Gel L.68 A.52, 95 2.15 I1'1l11., 15% Mieroporous Silica in Base Gel in Base Temperature, C 420 430 440 420 430 440 Feedstock Density at 15 C 809 822 815 819 814 810 810 810 819 815 814 813 815 Your Point, C. +11 +1 10 4 13 --10 10 +4 7 4 --13 10 7 Cloud Point, 0 +13 +2 6 3 10 8 -8 3 4 4 9 8 5 Paralfins, Percent wt 13. 8 3. 7 1 Distillation ASTM, 0:

PI 248 70 70 70 7O 70 70 70 70 70 70 70 70 5% 297 125 76 105 103 102 98 98 114 116 100 94 104 50%.- 352 302 290 300 287 288 283 303 300 306 291 287 296 388 374 353 360 357 357 354 359 362 363 357 357 358 95%.- 400 387 364 365 370 375 369 371 378 379 309 370 373 PF 400 388 379 378 370 383 380 384 381 382 377 378 381 Yield, Percent wt 98 97 97 96 96 9G 95 97 97 96 96 98 Catalyst composition:

} 13.3% SiOz, 10.64% M003, 0.55% 000, 75.51% A1103.

Table 9 [Catalyst 14.43 (see Table 3)] Temperature, C 415 390 390 390 360 415 390 Pressure, kg/cm. 35 70 55 40 70 H l./h 100 100 60 100 100 120 80 160 Space Velocity, v.lv./l1r 5 5 7 3 5 5 8 6 4 8 Feedstock Density at 15 C 1. 869 851 854 854 851 858 852 856 Pour Point, O +11 +11 +11 +11 +11 +11 +11 +11 Cloud Point, 0- +13 +12 +12 +12 +12 +12 +12 +12 Sulphur, Percent W 1. 6 0.36 0. 57 0. 74 0.30 O. 9" 0. 40 0.76 Distillations ASTM,

I.B.P S0 270 340 383 393 400 What we claim is:

1. A process for the treatment of distillate petroleum fractions boiling within the range 150-450 C. to lower the pour point at least C. without material reduction in the specific gravity and diesel index of said distillate fractions, comprising contacting the distillate fraction as feedstock in a treating zone and in the presence of hydrogen with a dehydrogenation catalyst on a silica-alumina base whose silica content is in the range 5 to 14% by Weight of total catalyst, the hydrogen to hydrocarbon mole ratio being from 5 to 1 to 20 to 1; maintaining a selected temperature and a selected space velocity in said zone, said selected temperature in said zone being maintained at least about 400 C. but not higher than about 480 C. and being a temperature at which, at said selected space velocity, not more than 20% wt. of the feedstock is converted to material boiling below 150 C. and said selected space velocity being at least equal to the space velocity at which at said selected temperature not more than 20% wt. of the feedstock is converted to material boiling below 150 C. but not exceeding 3.0 v./v./hr.; maintaining a selected pressure in said zone in the range 100-1500 p.s.i. ga., said selected temperature and said selected space velocity being correlated to reduce the pour point of the feedstock such that the pour point of the material of the treated distillate fraction boiling above 150 C. is at least 5 lower than the pour point of the feedstock, and recovering the treated distillate fraction.

2. A process according to claim 1, wherein the temperature within said temperature range is such that not more than 15% wt. of the feedstock is converted to material boiling below 150 C.

3. A process according to claim 1, wherein the feedstock consists of a heavy gas oil in admixture with to 100% by volume of a lower boiling distillate such as kerosine.

4. A process according to claim 1, wherein the silica content has been derived fiom a silicon compound with which the alumina has been impregnated.

5. A process according to claim 4, wherein said silicon compound is ethyl silicate.

6. A process according to claim 1, wherein the silicaalumina base of the catalyst consists of a mixture of preformed alumina and silica.

7. A process according to claim 1 wherein the pressure is above the equilibrium pressure of the feedstock at the particular combination of correlated temperature and 10 space velocity, whereby reduction of the diesel index is at least minimized.

8. A process for the treatment of distillate petroleum fractions boiling within the range ISO-450 C. to lower the pour point at least 5 C. without material reduction in the specific gravity and diesel index of said distillate fractions, comprising contacting the distillate fraction as feedstock in a treating zone in the presence of hydrogen with a catalyst consisting essentially of 5-15 by weight of molybdenum trioxide supported on a silica-alumina base, the silica content being in the range 5-14% by weight of total catalyst, the hydrogen to hydrocarbon mole ratio being from 5 to 1 to 20 to 1; maintaining a selected temperature and a selected space velocity in said zone, said selected temperature in said zone being maintained at least about 400 C. but not higher than about 480 C. and being a temperature at which, at said selected space velocity, not more than 20% wt. of the feedstock is converted to material boiling below C., and said selected space velocity being at least equal to the space velocity at which at said selected temperature not more than 20% wt. of the feedstock is converted to material boiling below 150 C. but not exceeding 3.0 v./v./hr.; maintaining a selected pressure in said zone which is greater than the equilibrium pressure of the feedstock at said selected contacting temperature and said selected space velocity but not greater than about 1500 p.s.i. ga., said selected temperature and said selected space velocity being correlated to reduce the pour point of the feedstock such that the pour point of the material of the treated distillate fraction boiling above 150 C. is at least 5 C. lower than the pour point of the feedstock, and recovering the treated distillate fraction.

9. A process according to claim 8, wherein the molybdenum oxide content is 10 to 11%.

10. A process in accordance with claim 8 wherein the catalyst further includes cobalt oxide in an amount of .2-1% by weight with the molybdenum trioxide being present in an amount of 5 to 15%.

11. A process according to claim 10, wherein the molar ratio of the metals Co to M0 is 0.1.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 125,509 Marchv 17, 1964 Bernard Laine et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 1, line 43, for "catalyt'! read catalyst column 5, line 51, for "obtined" read obtained column 6, line 29, for "sulfur acid" read sulfuric acid line 48, for "aof" read of Signed and sealed this 15th day of September 1964,,

(SEAL) Attest:

ERNEST W. SWIDER- EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. A PROCESS FOR THE TREATMENT OF DISTILLATE PETROLEUM FRACTIONS BOILING WITHIN THE RANGE 150-450*C. TO LOWER THE POUR POINT AT LEAST 5*C. WITHOUT MATERIAL REDUCTION IN THE SPECIFIC GRAVITY AND DIESEL INDEX OF SAID DISTILLATE FRACTIONS, COMPRISING CONTACTING THE DISTILLATE FRACTION AS FEEDSTOCK IN A TREATING ZONE AND IN THE PRESENCE OF HYDROGEN WITH A DEHYDROGENATION CATALYST ON A SILICA-ALUMINA BASE WHOSE SILICA CONTENT IS IN THE RANGE 5 TO 14% BY WEIGHT OF TOTAL CATALYST, THE HYDROGEN TO HYDROCARBON MOLE RATIO BEING FROM 5 TO 1 TO 20 TO 1; MAINTAINING A SELECTED TEMPERATURE AND A SELECTED SPACE VELOCITY IN SAID ZONE, SAID SELECTED TEMPERATURE IN SAID ZONE BEING MAINTAINED AT LEAST ABOUT 400*C. BUT NOT HIGHER THAN ABOUT 480*C. AND BEING A TEMPERATURE AT WHICH, AT SAID SELECTED SPACE VELOCITY, NOT MORE THAN 20% WT. OF THE FEEDSTOCK IS CONVERTED TO MATERIAL BOILING BELOW 150*C. AND SAID SELECTED SPACE VELOCITY BEING AT LEAST EQUAL TO THE SPACE VELOCITY AT WHICH AT SAID SELECTED TEMPERATURE NOT MORE THAN 20% WT. OF THE FEEDSTOCK IS CONVERTED TO MATERIAL BOILING BELOW 150*C. BUT NOT EXCEEDING 3.0V./V./HR.; MAINTAINING A SELECTED PRESSURE IN SAID ZONE IN THE RANGE 100-1500 P.S.I. GA., SAID SELECTED TEMPERATURE AND SAID SELECTED SPACE VELOCITY BEING CORRELATED TO REDUCE THE POUR POINT OF THE FEEDSTOCK SUCH THAT THE POUR POINT OF THE MATERIAL OF THE TREATED DISTILLATE FRACTION BOILING ABOVE 150*C. IS AT LEAST 5*C. LOWER THAN THE POUR POINT OF THE FEEDSTOCK, AND RECOVERING THE TREATED DISTILLATE FRACTION.