US3125505A

US3125505A - Treatment of petroleum fractions to

Info

Publication number: US3125505A
Authority: US
Publication date: 1964-03-17
Anticipated expiration: 1981-03-17

Description

United States Patent 3,125,505 TREATMENT OF PETROLEUM FRACTIONS T LOWER THE POUR POiNT Kenneth Tupman and Donald Richard Irving, Sunbury- 'on-Thames, England, assignors to The British Petroleum Company Limited, London, England, a joint-stock corporation of Great Britain No Drawing. Filed Aug. 8, 1961, Ser. No. 129,962 Claims priority, application Great Britain Aug. 19, 1960 6 Claims. (Cl. 208-443) This invention relates to the treatment of hydrocarbon fractions, particularly petroleum fractions, boiling above 150 C., and the principal object of the invention is to provide a process by means of which the cloud point, pour point or freezing point of such fractions may be lowered.

According to the invention a hydrocarbon fraction boiling above 150 C. is contacted in the presence of hydrogen with a catalyst comprising a platinum group metal on a support containing a major proportion of alumina but less than 1% wt. of halogen at a temperature of at least 700 F. but below the temperature at which substantial cracking occurs, a pressure of at least 100 p.s.i.g., and a space velocity not exceeding 8.0 v./v./ hr. and a product boiling above 150 C. having a pour point at least 5 F. lower than the pour point of the feedstock is recovered, the temperature and space velocity being correlated to give said lower pour point.

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 wt. of the feedstock is so converted.

The term fraction as used in this specification includes both fractions which are distillable at normal or reduced pressure, for example, gas oils and waxy distillates and also residues and portions thereof, for example deasphalted residues. Particularly suitable fractions for use as feedstocks are distillate fractions boiling within the range 150 to 450 C. and more particularly within the range 250 to 450 C.

It has been found that it is not necessary to desulphurise the feedstock prior to submitting it to the pour point reduction process, although such a preliminary desulphurisation may be given if desired. When operating with a sulphur-containing feedstock (for example one with more than 0.1 wt. of sulphur) the process will normally effect considerable desulphurisation simultaneously with the lowering of the cloud point, pour point or freezing point. It has also been foundthat the process can be operated in the presence of considerable quantities of hydrogen sulphide, so that, for example, the process can be operated on the total efiluent of a previous hydrocatalytic desulphursation process.

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

The platinum group metal content of the catalyst may be within the range 0.01 to 5.0 percent Weight preferably 0.1 to 1.0 percent weight. The preferred platinum group metals are platinum and palladium. The catalyst support material contains, as stated above, at least a major proportion of alumina and it may also contain a minor pro- 'ice portion of one or more of the oxides of metals of groups II, III and IV of the periodic table. Preferably the amount of the group II, III or IV metal oxides is from 525% wt. of the support. Examples of suitable supports include alumina, silica/ alumina, titania/ alumina, zirconia/alumina and beryllia/ alumina. A support of alumina and from 5 to 25/ wt. of silica is particularly preferred. The support material may also contain a minor proportion of one or more compounds (including oxides) of nonmetallic elements in groups III, IV and V for example boron or phosphorus, which may if desired be combined or mixed with any of the metal oxides of groups II, III and IV. Preferably the amount of the compounds of the non-metallic elements is from 5 to 25% wt. of the support, a support of alumina and from 5 to 25% Wt. of the support of boron oxide (calculated as B 0 being particularly preferred. As stated above if halogen, for example chlorine or fluorine, is present is should not exceed 1% Wt. of the support.

The catalyst may be employed as a fixed bed, a moving bed or a fluidised bed.

An essential requirement to obtain pour point reduction with any given catalyst and operating conditions employed is a correlation of temperature and space velocity. In general the higher the temperature, the higher the space velocity that can be employed, the upper limit of temperature, at any given space velocity, being determined by the amount of cracking occurring. The feedstock used, the activity of the catalyst used and the reduction of pour point required should also be taken into account when selecting the process conditions. When treating the heavier feedstocks, for example, the operating conditions may be more severe (i.e. conditions of higher temperature and/ or lower space velocity) than when treating lighter feedstocks. When using a more active catalyst, for example those having silica-alumina or boria-alumina supports, less severe conditions may be used, an equivalent reduction in pour point being obtainable at a lower temperature and/ or higher space velocity. In practice the temperature .will not normally exceed 950 F. and it is preferably at least 750 F. The pressure may be from to 1500 p.s.i.g. and the hydrogen:hydrocarbon mole ratio from 1:1 to 20:1. In practice the space velocity will not normally be less than 0.1 v./v./hr. and it is preferably not less than 0.5 v./v./hr.

The process may be operated with or without a net hydrogen consumption. A net hydrogen consumption is generally favoured by increase in pressure, and for any given temperature and space velocity the pressure at which the hydrogen consumption and hydrogen production are in balance is known as the equilibrium pressure. It is generally preferred to operate at or above this pressure because this results in an increase in the on stream time before catalyst regeneration or replacement is necessary. Another advantage of this type of operation is, for example, that when processing feedstocks such as gas oils for the production of diesel oils reduction of the diesel index is minimized or avoided. The principal advantages of operating below the equilibrium pressure are that a reduction in the specific gravity of the distillate is minimised or avoided, and that hydrogen is produced, this hydrogen being then available for use in other hydrogenconsuming processes.

Operation of the process using a fixed bed of catalyst is carried out in the normal manner, which is to increase the temperature gradually as the run continues in order Table 1 Pressure, 13.8.14; 500 500 500 750 l, 000 750 750 750 Temperature, F 800 825 825 825 825 825 825 825 Space Velocity, v./v./l1r 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Gas Rate (Recycle), S.e.f./b- 10,000 10, 000 10, 000 10, 000 10,000 10, 000 5, 000 2, 500 Recycle Gas H2 content, percent 9 89 9 89 93 8 85 85 Ha Make yes yes yes yes yes yes yes Hz Consumption yes Product (Unstabil' Cloud Point, F 8 2 Pour Point, F 8 -10 -10 5 -20 20 Product (Boiling 150 0.):

Yield, percent wt 97 94. 5 93. 5 93. 5 95 93. 5 02. 5 93. 5

Raw Hydro- Feed fined Feed SG at F. '60 F 0. 842 0. 829 0. 83 1 0. 835 0. 840 0. 835 0. 829 0. 835 0.833 0.837

Diesel Index 66 59 55 54 56 62 56 57 54 Cloud Point, F 18 18 6 2 '8 8 4 -8 Pour Point, F... 15 15 5 5 -5 15 0 -15 10 15 to maintaln the quality of the product at the des1red The first set of results at 500 p.s.1.g. shows the advanlevel.

The process of the present invention will normally tage of operating at the higher temperature of 825 F. The second set of results at 825 F. shows the effect of lower all the three points specified viz. cloud point, pour 25 pressure and indicates that the equilibrium pressure for po1nt and freezing point. Which point is taken as the the feedstock and conditions used lies between 750 and criterion for any particular operation will depend on the 1000 p.s.i.g. The third set of results shows that for the feedstock used and the use to which the product is to feedstock and conditions used the results are independent be put. The freezing point is normally only of importance of recycle rate within the range 10,000-2,500 s.c.f./b. with the lower boiling feedstocks. 30

The invention is illustrated by the following examples: EXAMPLE 2 EXAMPLE 1 The hydrofined gas oil of Example 1 was processed over A gas oil having a boiling range of 250-360 C. ASTM the catalyts of Example 1 in an extended run to assess the was hydrocatalytically desulphurised to reduce the sulr length of processing period obtainable. The process conphur content from 1.25% wt. to 0.04% wt. The condiditions used and the results obtained are given in Table 2 tions used were as follows. below.

Table 2 Hydro- Hours on Stream Raw fined Feed Feed Pressure, p.s.i.g 750 750 750 750 750 750 750 750 750 750 750 Temperature, F. 020 320 325 825 825 330 330 330 345 345 345 Space Velocity, v./v. 1.0 1.0 1.0 1. 0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Gas Rate (recycle), s.e. 2, 500 2,560 2, 500 2, 560 2, 640 2,630 2,510 2,560 1,030 1,000 930 Recycle GasDensity.. 0.196 0.100 0.200 0. 222 0. 200 0.200 0.132 0.222 0. 230 0. 242 Recycle Gas In Content, percent vol 87.0 33.0 33.5 30.0 33.5 88.5 88.2 30.5 31.0 85.0 34.0 Recycle Gas HzS Content, percent vol. Nil Nil Nil Nil Nil Nil Nil Nil Nil Nil Nil Exit Gas Make, s.c.l./b 133 101 132 117 151 125 30 30 Product Gas Make, s.c.f./b 53 53 60 57 43 00 2s 54 73 7s 74 Liquid Recovery, pereentwt 101.1 00.3 00.2 99.7 99.2 99.2 100.0 103.0 03.7 00.2 Product (Unstabilised):

Cloud Point, "F -10 -2 -4 -4 -2 -4 -2 0 -2 2 4 Pour Point, "F -15 -10 -10 -5 -10 -10 -10 -10 -10 -10 -10 Product (Boiling 150 0.):

Yield, percent wt 93.3 04.1 03.0 04.4 03.9 93.6 04.0 04.0 90.0 91.3 02.8 Cloud Point, F. 2 0 0 -2 0 0 2 2 8 4 Pour Point, F -10 -5 -5 -5 -5 -5 -5 -5 -10 -5 -10 Temperature, F 780. These results show that a stabilised product was ob- Pressure, p.s.i.g 1000. tained in a yield of about 93% 94% wt. with a pour point Space velocity, v./v./hr 8.0. at least 20 F. below that of the feedstock. The process Recycle gas rate, s.c.f./ b 4000. 60 was operated at a fixed recycle rate and fixed pressure be- Catalyst: low the equilibrium pressure giving a net production of Molybdenum oxide (M00 14.3% wt. hydrogen. However in spite of this the rate of loss of Cobalt oxide (C00) 2.4% wt. catalyst activity was low. Between 428 and 512 hours Alumina Balance. on stream the recycle rate was reduced voluntarily to The hydrofined product was then processed over a platinum catalyst to reduce its pour point. The catalyst composition was: Percent weight After the processing the product was stabilised to remove a small proportion of material boiling below 150 C. and give a gas oil of the required flash point (150 C.).

show that operation at low recycle rates was possible. The run was ended voluntarily at 800 hours while the catalyst still had considerable activity. Regeneration of the catalyst restored the activity completely.

EXAMPLE 3 A heavy gas oil was hydrocatalytically desulphurised over a catalyst of 2.4% wt. cobalt oxide and 14.3% wt. molybdenum oxide on alumina. The process conditions used and inspection data on the feed and product are given in Table 3 below.

Table 3 Catalyst COMO/Alumina Operating conditions:

Pressure, 1) s i g..- 1,000 Temperature, 730 Space Velocity, v/ 2.0 Gas Recycle Rate, s.c.f./b 1,000

Feed Product Results:

Specific Gravity at 60 F./60 F 0.876 0.850 ASTM Distillation, 0.:

IBP 208 146 Vol. Recovered at 320 278. 5 50% Vol. Recovered at 345 333 90% Vol. Recovered at 380 371 FBP 395 391 Sulphur Content, percent wt. 1. 91 0.08 Diesel Index 57/58 62/63 Cloud Point, F. 58 60 Pour Point, F 50 50 The desulphurised heavy gas oil was then processed to reduce its pour point over a platinum catalyst having the composiiton given in Example 1.

The process conditions used and the results obtained are given in Table 4 below.

The results show that the regenerated catalyst had an activity comparable to a fresh catalyst and that it was capable of reducing the pour point of a heavy gas oil over a processing period oi". at least 1100 hours. Alterations in the process conditions made at 840 hours on stream and after were made for the purposes of assessing the effect of increased temperature and space velocity and not to compensate for a decline in catalyst activity, and they show that increased temperatures give a further 0 reduction in pour point and allow the use of higher space velocities.

' EXAMPLE 5 A light gas oil was hydrocatalytically desulphurised over a catalyst of 2.4% wt. cobalt oxide and 14.3% -wt.

molybdenum oxide on alumina under the following conditions:

The gas oil feedstock had an ASTM boiling range of 250-360 0., a sulphur content of 1.25% wt, a cloud point of i+18 F. and a pour point of +l5 F. Pre- Table 4 Hours on Stream Feed Pressure, p s i g 750 Temperature, F 860 Space Velocity, v./v./hr 0.5 Gas Recycle Rate, s.c.f. 10,000 Recycle Gas H2 Content, percent vol 80 Recycle Gas Density, g./l 0.265 Exit Gas Make, s.c.f./b Nil 85 Yield, percent wt 100 Diesel Index. 62/63 Cloud Point, F- 60 Pour Point, F 50 The table shows the elfectiveness of the platinum alumina catalyst for reducing the pour point of heavy gas oils over a processing period of at least 500 hours. It also shows that lowering the space velocity at a given temperature gives a further reduction in the pour point.

EXAMPLE 4 The catalyst used in Example 3 was regenerated by burning off the deposits formed in an oxygen-containing gas. It was then re-used to process a further quantity off vious experiments on the desulphurisation of such a feedstock under these process conditions showed a reduction of sulphur content to 0.04% wt. but no reduction of the cloud or pour point.

The total efliuent from the hydrocatalytic desullphur-isation, including all the H S produced was then contacted with a platinum alumina catalyst having the following composmon: Percent weight Platinum 0.75

Flu the desulphumsed heavy gas 011 used in Example 3. t The process conditions used and the results obtained i Balalme are given in Table 5 below.

Table 5 Hours on Stream Feed Pressure, p.s.i.g 750 750 750 Temperature, F 830 860 880 Space Velocity, v./v./hr 1.0 1.0 1.0 Gas Recycle Rate, sci/b 5, 000 10,000 10,000 Recycle Gas Hz Content, percent vol 81 Recycle Gas Density, g.[l 0 0.200 0.250 Exit Gas Make, s.c.f./b 25 H2 Consumption, s.c.f. N11 Nil Nil Product Gas Make, s.c.i./b 75 Product (Unstabilised):

Cloud Point, F- 50 46 38 40 30 Feed to desulphur iser Hours on Stream Cloud Point, F Pour Point, F S content, percent wt EXAMPLE 6 The gas oil of Example was contacted without any previous desulphurisation, with a platinum-alumina catalyst having the following composition:

Percent weight Platinum 0.57 Chlorine 0.81 Alumina Balance The process conditions used were:

Temperature 820 F. Pressure 750 p.s.i.g. Space velocity 1.0 v./v./hr. Gas rate 2,500 s.c.f. of hydrogen/ b.

The results obtained are given in Table 7 below:

Table 7 Hours on Stream Feedstock Cloud Point, F +18 4 -4 2 0 Pour Point, F 15 10 10 10 Seontent,pereent wt 1.25 0.02 0.02 0.02 0.02

EXAMPLE 7 A gas oil of 250350 C. ASTM boiling range containing 1.25/ wt. sulphur and having a pour point of 20 F. was processed over the catalyst of Example 1. A series of runs was carried out at 750 p.s.i.g. and a gas rate of 10,000 s.c.f. of hydrogen/b., the temperature and space velocity being varied to indicate the correlation required to reduce the pour point of the feedstock. The results obtained are given in Table 8 below and are in each case the initial results obtained with fresh catalyst.

The results show, while substantially complete desulphurisation was obtained under all conditions, pour point reduction was not always obtained. There is thus no connection between desulphurisation and pour point reduction.

With the particular catalyst 700 F. is below the minimum practicable temperature. Pour point reduction is not obtained even at 0.5 v./v./hr. and a very low space velocity would be necessary to obtain pour point reduction. Raising the temperature to 800 F. gives pour point reduction and allows a higher space velocity to be used. At 900 F. a space velocity of 4 v./v./hr. gives a good reduction but 8 v./v./hr is the limiting space velocity at that temperature and with the catalyst used. A space 8S velocity of 1 v./v./hr. at 900 F. gives a large reduction in pour point, but the amount of cracking exceeds that which is desirable.

EXAMPLE 8 The gas oil of Example 7 was processed over three different catalysts. These were:

(1) The catalyst of Example 1, viz. 0.75% Wt. platinum, 0.35% chlorine, 0.35% wt. fluorine and the balance alumina.

(2) A catalyst of 1% wt. platinum on a support of 10% wt. silica and wt. alumina.

(3) A catalyst of 0.54% wt. platinum, 0.75%wt. chlorine, 9.0% Wt. boron oxide (B 0 and the balance alumina.

The process conditions in each case were:

Temperature 775, 800 and 825 F. Pressure 500 p.s.i.g.

Space velocity 1.0 v./v./hr.

Gas rate 5000 s.c.f. of hydrogen/b.

The results obtained are given in Table 9 below:

Table 9 Pour Point Catalyst Feed 775 F. 800 F. 825 F.

1. Pt/alumina 20 20 10 0 2. Pt/sllicaalumina 20 0 5 30 3. Pt/boria-alumina 20 55 60 -65 The results show the much greater activity of the silicaand boria-containing catalysts. This greater activity allows considerably wider variation in the correlation of temperature and space velocity, a given reduction in pour point being obtainable at lower temperature and/or higher space velocity.

We claim:

1. A process for the treatment of distillate petroleum fractions boiling within the range ISO-450 C. to lower the pour point at least 5 F. 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 catalyst comprising a platinum group metal on a support containing a major proportion of alumina, from 525% by weight of the support of a material selected from the group consisting of group II metal oxides, group III metal oxides, group IV metal oxides, and group III non-metallic oxides, group IV non-metallic oxides, and group V non-metallic oxides, and mixtures of the foregoing, and less than 1% wt. of halogen, the hydrogen to hydrocarbon mole ratio being from 1 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 at 700 F. but not higher than about 950 F. 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 0.01 v./v./hr. but not higher than 8.0 v./v./hr. at which, at said selected temperature, not more than 20% wt. of the feedstock is converted to material boiling below 150 C.; maintaining a selected pressure in said zone in the range -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 C. is at least 5 F. lower than the pour point of the feedstock, and recovering the treated distillate fraction.

2. A process in accordance with claim 1 wherein the platinum group metals is present in an amount from 0.01 6. A process as claimed in claim 1 wherein the seto 5.0% wt. lected compound is boron oxide.

3. A process as claimed in claim 1 wherein the fraction is sulphur-containing References in the file Of patent 4. A process as claimed in claim 1 wherein the plat- 5 UNITED STATES PATENTS inum group metal is platinum.

5. A process as claimed in claim 1 wherein the metal 23 2 3: 3 oxide is silica.

UNITED STATES 1P CERTIFICATE ATENT OFFICE F CORRECTION March l7, 19

Patent No.

Kenneth Tupman et a1.

It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Pa corrected below.

tent should read a for "5 to ZS/wt."

; columns 3 and 4, Table l hereof, for

for "1 25/wt.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD]. BRENNEE Attesting Officer Commissioner of Patents

Claims

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*F. 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 CATALYST COMPRISING A PLATINUM GROUP METAL ON A SUPPORT CONTAINING A MAJOR LPROPORTION OF ALUMINA, FROM 5-25% BY WEIGHT OF THE SUPPORT OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF GROUP II METAL OXIDES, GROUP III METAL OXIDES, GROUP IV METAL OXIDES, AND GROUP III NON-METALLIC OXIDES, GROUP IV NON-METALLIC OXIDES, AND GROUP V NON-METALLIC OXIDES, AND MIXTURES OF THE FOREGOING, AND LESS THAN 1% WT. OF HALOGEN, THE HYDROGEN TO HYDROCARBON MOLE RATION BEING FROM 1 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 AT 700*F. BUT NOT HIGHER THAN AOBUT 950*F. 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 0.01 V./V./HR. BUT NOT HIGHER THAN 8.0 V/V./HR. AT WHICH, AT SAID SELECTED TEMPERATURE, NOT MORE THAN 20% WT. OF THE FEEDSTOCK IS CONVERTED TO MATERIAL BOILING BELOW 150* C.; MAINTAINING A SELECTED PRESSURE IN SAID ZONE IN THE RANGE 100-1500 P.S.I.GS., 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*F. LOWER THAN THE POUR POINT OF THE FEEDSTOCK, AND RECOVERING THE TREATED DISTILLATE FRACTION.