US3125511A

US3125511A - Treatment of hydrocarbon fractions to

Info

Publication number: US3125511A
Authority: US
Priority date: 1960-10-28
Publication date: 1964-03-17
Anticipated expiration: 1981-03-17
Also published as: GB943237A; BE609624A; NL270707A; NL270706A; BE609623A; US3125510A

Description

United States Patent 3,125,511 TREATMENT OF HYDROCARBON FRACTIONS TO OBTAIN A LOWER POUR POINT PRODUCT Kenneth Tupman and Peter Thomas White, both of Sunbury-on-Thames, England, assignors to The British Petroleum Company Limited, London, England, a jointstock corporation of Great Britain No Drawing. Filed Oct. 24, 1961, Ser. No. 147,208 Claims priority, application Great Britain Oct. 28, 1960 8 Claims. (Cl. 208264) 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 and at least 1% wt. of halogen at a temperature of at least 600 F., a pressure of at least 100 p.s.i.g., and a space velocity not exceeding 8.0 v./v./hr., the temperature and space velocity used being correlated to give a product boiling above 150 C. having a pour point at least F. lower than the pour point of the feedstock.

Preferably the temperature is below that at which substantial cracking occurs, and 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 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 found that 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 effluent of a previous hydrocatalytic desulphurisation 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 amount of halogen is preferably in the range 1 to 15% wt. and more particularly 1 to 10% wt. Examples of suitable halogens are fluorine and chlorine, the former being preferred both on account of the greater effectiveness for pour point reduction and the greater stability of fluorine-containing catalysts as compared with similar chlorine-containing catalysts.

The halogen may be incorporated into the catalyst by treating the catalyst with a halogen compound, preferably one containing halogen, together with one or more of the elements of carbon, hydrogen or oxygen. Examples of suitable halogen compounds are hydrogen halides and halogen derivatives of aliphatic hydrocarbons having from 1 to 4 carbon atoms. The halogen is normally in- 3,125,511 Patented Mar. 17, 1964 ice corporated in the catalyst already consisting of a platinum group metal on a support and this catalyst may be halogen free or it may already contain a small amount (less than 1% wt.) of halogen. Examples of suitable ways in which the halogen may be incorporated into the catalysts are described in the specific examples.

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 alumina may be the only refractory oxide present in the catalyst. However, if desired the catalyst may also contain a minor proportion 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. The support material may also contain a minor proportion of one or more compounds (including oxides) of non-metallic 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.

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 one containing fluorine rather than chlorine, 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 is preferably at least 700 F. Similarly in practice the space velocity will not normally be less than 0.1 v./v./hr., and more particularly not less than 0.5 v./ v./ hr. It preferably does not exceed 8 v./v/.hr. and more particularly does not exceed 5 v./v./hr. The pressure may be from to 1500 p.s.i.g. and the hydrogenzhydrocarbon mole ratio from 1:1 to 20:1.

The process may be operated with or without a nett 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 minimised 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 by- 3 drogen 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 to maintain the quality of the product at the desired level.

The process of the present invention will normally lower all the three points specified viz. cloud point, pour point and freezing point. Which point is taken as the criterion for any particular operation will depend on the feedstock used and the use to which the product is to be put. The freezing point is normally only of importance with the lower boiling feedstocks.

In copending U.K. application No. 37,124/ 60 a process for the treatment of hydrocarbon fractions boiling above 150 C. to reduce their cloud point, pour point, or freezing point is described in which the fractions are contacted with a catalyst in the presence of hydrogen and with the addition of halogen to the reaction zone, preferably in an amount equivalent to from 0.001 to 1% wt. by weight of feedstock. In copending U.K. application No. 8,248/ 61 a process for the treatment of hydrocarbon fractions boiling above 150 C. to reduce their cloud point, pour point or freezing point is described, in which the fractions are first treated to reduce their content of aromatic hydrocarbons, or nitrogen compounds, or both. Such processes may, if desired, be combined with the process of the present invention.

The invention is illustrated by the following examples:

EXAMPLE 1 A reforming catalyst containing 0.75% wt. platinum 0.35% wt. chlorine and 0.35% wt. fluorine on an alumina support was treated with an excess of a mixture of 3 parts water and 1 part concentrated HCl at a temperature below 10 C. for 2 hours. The catalyst treated was then dried for 12 hours at 105 C. and calcined in air at 550 C. for 2 hours. The chlorine content of the catalyst was 1.2% wt. The catalyst was then used to reduce the pour point of a heavy gas oil. The heavy gas oil had been previously hydrocatalytically desulphurised over a catalyst of 2.4% wt. cobalt oxide and 14.3% wt. molybdenum oxide under the process conditions and with the results set out below:

Operating Conditions Catalyst Co-Mo/Alumina Pressure p.s.i.g 1,000 Temperature F 730 Space velocity v./v./hr 2.0 Gas recycle rate s.c.f./b 1,000

Results Feed Product Specific Gravity at 60l00 F O. 876 0. 850 ASTM Distillation:

IBI, C 298 146 10% Vol Recovered at C. 320 278. 5

50% Vol Recovered at C 345 333 90% Vol Recovered at, C. 380 371 FBP, C 395 391 Sulphur Content, wt 1. 91 0.08 Diesel Index 57/58 02/62 Cloud Point, F 58 60 Pour Point, F 50 50 Solid Pi11t, F 45 49 The pour point reduction process was carried out under the following conditions:

Temperature F 800 Pressure p.s.i.g 500 Space velocity v./v./hr 1.0 Recycle rate s.c.f./b 5,000

The pour point of the product was 35 F. When the same heavy gas oil was treated with a portion of the platinum/chlorine/fluorine/alumina/catalyst d which had not been further treated with HCl the pour point was only reduced to 45 F.

EXAMPLE 2 The platinum/ chlorine/ fiuorine/ alumina catalyst of Example 1 was dried for 2 hours at 570 F. in nitrogen and treated in a current of anhydrous HCl vapour using nitrogen carrier gas at 570 F. for 3 hours. The chlorine content of the treated catalyst was 2.0% wt.

The treated catalyst when used to treat the heavy gas oil of Example 1 under the same conditions as Example 1, gave a product with a pour point of 10 F.

EXAMPLE 3 The platinum/ chlorine/ fiuorine/ alumina catalyst of Example 1 was dried for 2 hours at 570 F. in nitrogen and treated in a current of dry nitrogen containing carbon tetrachloride vapour at 570 F. for 2 hours. It was then flushed with N at 570 F. for 1 hours.

The treated catalyst when used to treat the heavy gas oil of Example 1 under the process conditions of Example 1, gave a product with a pour point of 20 F.

EXAMPLE 4 ml. of a commercial platinum-on-alumina catalyst, containing 0.58 percent weight of platinum and 0.81 percent weight of chlorine, was placed in a vertical reactor and dried by purging with nitrogen for one hour at 450 C. Carbon tetrafluoride was then passed over the catalyst for 30 minutes at 450 C. at a rate of 100 ml. CF per minute. This was followed by dry nitrogen for a further one hour. The fluorine content of the treated catalyst was 6.3% wt.

The catalyst was then used to reduce the pour point of a heavy gas oil. The heavy gas oil had been previously hydro-catalytically desulphurised over a catalyst of 2.4 percent weight cobalt oxide and 14.3 percent weight molybdenum oxide on alumina under the process conditions given below:

Operating Conditions Catalyst CoMo/ alumina Pressure p.s.i.g 1,000 Temperature F 730 Space velocity v./v./hr 2.0 Gas recycle rate s.c.f./b 1,000

Results Feedstock Product Specific gravity at 60 F./60 F 0. 876 0.850 ASTh/I Distillation:

IBP C 298 146 10% volume recovered at, C... 320 278. 5

50% volume recovered at, C 345 333 00% volume recovered at, C... 380 371 FBP, C 305 301 Sulphur content, percent wt 1. 01 0.08 Cloud point, F 58 60 Pour point, F 50 50 The pour point reduction process was carried out under the following conditions and with the results given below:

A comparison of the results obtained with those obtained in Examples 1 to 3 shows the greatly improved results obtained with fluorine. At 800 F. the pour point reduction was F. whereas in Examples 1 to 3 using 6 EXAMPLE 7 100 ml. of commercial platinum-on-alumina catalyst,

EXAMPLE 5 containing 0.58 percent weight of platinum and 0.81 percent weight of chlorine was added slowly to an equal 100 ml. of commercial platinum-on-alumina catalyst, 5 Volume of 5 Percent i aqueous hlfdrogen fluoride containing 0.58 percent weight of platinum and 0.81 perand the bulk kept c001 The i was cent weight f chlorine was added Slowly to an equal allowed to stand for 30m1nutes, the excess llqllld decanted volume f 5 percent weight aqueous hydrogen fluoride oil and the catalyst dried at 105 C. for 2 hours and then Th b lk was i d and maintained at through calclned at 500 C. for 1 hour. The fluorine content of out. The mixture was then allowed to stand for 30 the catalyst was 60% H minutes, the excess liquid decanted off and the catalyst A 223L375, ASTM bollmg range Stralght run gas dried at 105 C. for two hours and then calcined at 011 (Sulphur content 124% Pour Point was 500 C. for one hour. The fluorine content of the treated Processed Over this catalyst under a variety of (migrating catalyst was 0% wt conditions. The results obtained were as follows:

h The catalyst was then used to reduce the pour point of eavy gas oi which had been previously hydrocatal tical- 1y desulphurised over a COMO/alumi catalyst feed- Catalyst HFtreated Pt/alumma Stock and feedsftock prePamfion as for Example Pressure, p.s.i.g 500 500 500 500 500 500 500 500 500 The pour point reduction process was carried out under Once through y the following conditions and wlth the results given below: ggg y fgggffl 000 000 000 000 M00 000 000 hr 1.0 1.0 1.0 2.0 2.0 2.0 3.0 3.0 3.0 Temperature, 1 050 750 800 075 775 825 700 750 800 Pour point reduc- Catalyst HFtreated Pflalumina tion, F N11 30 7o Nil 20 50 N11 5 1s ;g & jfig;: $8 T8 T8 398 98 38 This example illustrates the necessity of correlating the :3 hydrogen 5 r temperature and space velocity to give a reduction in rempeias're,"-="riiiij11:: 53% '33? 993 '333 '23? P Point At and 1 675 and 2 Pour point du tion, F- 5 25 45 100 120 120 v./v./hr., and 700 and 3 v./v./hr., the temperature is too low, at the space velocity used, to give pour point reduction with the particular catalyst and feedstock used. EXAMPLE 6 However, as the temperature is raised pour point reduction is obtained. At any given temperature a greater 500 ml. of a commercial platinum-on-alumina catalyst, degree of pour point reduction is obtained when using a containing 0.58 percent weight platinum and 0.81 perlower space velocity. cent weight chlorine, was charged to a vertical reactor We claim: and purged by recycling dry nitrogen at 670 F. and 1. A process for the treatment of distillate petroleum plant pressure of 98 p.s.i.g. until the Water content of fractions boiling within the range ISO-450 C. to lower the nitrogen leaving the reactor was less than 10 ppm. the pour point at least 5 F. without material reduction The plant was then pressurised to 118 p.s.i.g. with car n in the specific gravity and diesel index of said distillate tetrafiuoride and the gases recycled for 10 hours. fractions, comprising contacting the distillate fraction as The fluorine content of the resulting composite was feedstock in a treating zone and in the presence of by- 6.3 percent weight. drogen with a catalyst consisting essentially of a platinum A 223 375 C. ASTM boiling range straight run gas group metal on a support containing a major proportion oil was used to assess the activity of the above catalyst. of alumina and from 1 to 15% wt. of halog the y The test was carried out over an extended period and the 2 Q hyflfflcarbon mole ratio being from 1 t0 1 20 to operating conditions and results obtained are given below: malntalmng a Selected tempfifalllre and Selected p t velocity in said zone, said selected temperature in said zone being maintained at least at 700 F. but not higher Hours on stream than about 950 F. and being a temperature at which, at

said selected space velocity, not more than 20% wt. of

Feed 8M3 171477 367x369 the feedstock is converted to material boiling below 150 C. and said selected space velocity being at least 0.01

1 v./v./hr. but not higher than 8.0 v./v./hr. at which, at

55115.11: 9 i il is tl 750 said selected temperature, not more than 20% wt. of jggfg g g f Z g 2 8 the feedstock is converted to material boiling below 15 0 Gas recycle rate, s.c .f./b 10,000 10,000 C.; maintaining a selected pressure in said zone in the ggg fi DataUn' range 100-1500 p.s.i.g.a., said selected temperature and Cloud 3 1M31 22 +2 said selected space velocity being correlated to reduce ggig gg gg z figg g g; 3g the pour point of the feedstock such that the pour point stabilised: of the material of the treated d1st1llate fract1on boning Sulphur c0i'1tent, percent wt. 0.05 of the feedstock, and recovering the treated distillate ii s ercent wt 1 2 1 2 fraction- Gsisjgereentwtjjljzzi III: III: 312 2:4 5 2. A process as claimed in claim 1 wherein the fracif g tfi P" M3 mo tion is sulphur-containing.

Gas 011 (150 C r 151 e r l u 3. A process as claimed in claim 1 wherein the catalyst cent wt 10M contains from 1 to 10% wt. of halogen.

4. A process as claimed in claim 1 wherein the halo- 7 gen is fluorine.

This example illustrates not y the activity of the 5. A process as claimed in dlaim 1 wherein the catalyst catalyst for pour point reduction for a period of several contains from 0.01 to 5.0% wt. of the platinum group hundred hours on stream, but also the ability of the metal. catalyst to operate with a sulphur containing feedstock, 6. A process as claimed in claim 1 wherein the platinum giving simultaneous desulphurisation. group metal is platinum.

References Cited in the file of this patent UNITED STATES PATENTS Burton et a1 May 26, 1956 Cole Jan. 3, 1961

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 FREACTION, COMPRISING CONTACTING THE DISTILLATE FRACTION AS FEEDSTOCK IN A TREATING ZONE AND IN THE PRESENCE OF HYDROGEN WITH A CATALYST CONSISTING ESSENTIALLY OF A PLATINUM GROUP METAL ON A SUPPORT CONTAINING A MAJOR PROPORTION OF ALUMINA AND FROM 1 TO 15% WT. OF HALOGEN, THE HYDROGEN TO HYDROCARBON MOLE RATIO BEING FROM 1 TO 1 20 TO 1; MAIANTAINING 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 9,0 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.G.A., 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.