US3876525A

US3876525A - Pour point reduction of middle distillates

Info

Publication number: US3876525A
Application number: US374292A
Authority: US
Inventors: Li C Mih; John T Brandenburg
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1973-06-28
Filing date: 1973-06-28
Publication date: 1975-04-08
Anticipated expiration: 1992-04-08

Abstract

The pour point of a middle distillate oil is reduced by contacting the oil at an elevated temperature and pressure in the presence of hydrogen with a catalyst comprising a noble metal on a support comprising mordenite having a silica:alumina mol ratio between 10 and 15 to 1 and an alkali metal content of less than 1.0 wt. %.

Description

United States Patent 1 1 1111 3,876,525

Mih et al. 1 Apr. 8, 1975 POUR POINT REDUCTION OF MIDDLE 3.620.963 11/1971 Mulaskey 208/1 11 DISTILLATES 3.775398 ll/l973 Morris et al. 208/] ll 3.833.499 9/1974 Egan et al 208/1 ll Inventors: Li eacon; John 3.235.027 9/1974 Ward 208/111 Brandenburg, Hopewell Junction. both of Primary E.\'am1'nerDelbert E. Gantz [73] Assignee; Texaco Inc Ne Y k, N Y Assistant Examiner-S. Berger Filed: J 1973 ggggrney, Agent, or FirmThomas H. Whaley; Carl G.

[2]] Appl. No.: 374,292

[57] ABSTRACT U-S- t t I a [5 l] llfl. Cl ClOg 13/02 contacting the oil at an elevated temperature d [58] Fleld of Search 208/1 ll pressure i the presence of y g with a catalyst comprising a noble metal on a support comprising l56l References Clted mordenitc having a silicazalumina mol ratio between UNITED STATES PATENTS l0 and 15 to l and an alkali metal content of less than 3.539.498 11/1970 Morris et al. 208/11] .0 3,547 8()8 12/1970 Hzinsford 208/111 3,619,412 11/1971 Clement et al. 203/111 10 Clam, N0 Drawmgs POUR POINT REDUCTION OF MIDDLE DISTILLATES This invention relates to the treatment of petroleum oils. More particularly, it is concerned with a method for reducing the pour point of middle distillate oils.

Middle distillates conventionally serve as fuels such as diesel oils and furnace oils. The source of the crude oil to a large extent determines the pour point of the particular middle distillate. For convenience in the handling and in the use of these middle distillates. it is desirable for the pour point to be as low as practical consistent with the temperatures to which they may be exposed. Various methods have been suggested for lowering the pour point of these oils such as urea dewaxing for the removal of long chain paraffinic hydrocarbons of a waxy nature. However. not only are such procedures expensive but generally they also result in a large loss of yield and therefore are uneconomical.

The principal object of the present invention is to reduce the pour point of middle distillate oils without sustaining a large loss in yield.

According to our invention, the pour point of a middle distillate oil is reduced by contacting the oil at an elevated temperature and pressure in the presence of hydrogen with a catalyst comprising a noble metal on a support comprising mordenite having a silicazalumina mol ratio between and to l and an alkali metal content of less than 1.0 wt. /1, said support also comprising an amorphous refractory inorganic oxide in an amount between 5 and 50 wt. of the support.

The charge stocks to be treated in the process of our invention are middle distillate oils generally having a boiling range between about 500 and 800F. preferably between 550 and 750F. derived from crudes such as Amna, Arabian, Libyan, West Texas-New Mexico and the like. Ordinarily the middle distillates have a pour point ranging between about +45 and +55F.

The hydrogen used in the process of our invention need not necessarily be pure. Hydrogen having a purity of at least 60 volume 7c may be used although hydrogen of a purity. of from 65957( is preferred. Suitable sources of hydrogen are catalytic reformer by-product hydrogen, electrolytic hydrogen and hydrogen produced by the partial oxidation of hydrocarbonaceous material followed by shift conversion and CO removal.

The temperatures used in the process of our invention range between about 500 and 900F.. a range of 500625F. being preferred. Suitable pressures fall within the range of 500 to 5000 psig, a preferred range being 750-3000 psig. In a preferred embodiment, the middle distillate oil is contacted with the catalyst in the form of a fixed bed of particles at a rate between 0.1 and 10 volumes of oil per volume of catalyst per hour, a preferred rate being 0.5 to 5 v/v/hr., a still more preferred rate being between 1 and 2 v/v/hr. ln the preferred embodiment hydrogen is introduced with the oil at a rate between 100 and 10,000 standard cubic feet of hydrogen per barrel of oil preferably between 1000 and 7000 scfb.

The catalyst, in particulate form, may be used as a slurry, a moving bed or a fixed bed. The catalyst particles may either be in the form of pellets, spheroids or cylindroids. As mentioned above, in a preferred embodiment the catalyst is used as a fixed bed preferably made up of cylindrical particles. The reactant flow through the bed may be either upward or downward or countercurrent with the oil being passed downwardly through the bed countercurrently to an upwardly flowing stream of hydrogen. Preferably the reactant flow is downward.

The catalyst used in the process of our invention comprises a noble metal e.g. platinum, palladium, rhodium or iridium on a support. The noble metal may be present in the catalyst in an amount between about 0.1 and 5% based on the weight of the catalyst composite, a preferred amount being between 0.5 and 2 wt. 7c. The balance of the catalyst comprises a support containing both mordenite and an amorphous refractory inorganic oxide.

Mordenite is a crystalline alumino-silicate which occurs naturally or may be prepared synthetically. Typically it has an analysis of approximately 6.86 wt. Na O, 10.2 wt. A1 0 and 68.2 wt. SiO with the SiO :Al O mol ratio being approximately 11.421.

The mordenite which is present in the catalyst support contains less than 1.0 wt. 7: alkali metal and is referred to herein as hydrogen mordenite. It may be prepared by contacting a synthetic or natural mordenite with a dilute acid. This treatment effectively reduces the sodium content of the mordenite to less than 1.0 wt. However, care should be taken not to remove by leaching an excessive amount of the alumina present in the mordenite as it has been found that desirably the mordenite satisfactory for the purposes of our invention should have a silicazalumina mol ratio between about 10 and 15 to 1. Mordenite having a silicazalumina mol ratio in excess of 20:1 is unsatisfactory for use in our process. The mordenite may make up from 50-95 wt. of the support and preferably amounts to between 40 and wt. 7: of the support. The balance of the support comprises an amorphous. inorganic refractory oxide such as silica, alumina. titania, magnesia, zirconia and the like or mixtures thereof. Preferably the balance of the support comprises a mixture of silica and alumina and still more preferably the balance of the support is alumina, in an amount from 25-35 wt. 7r of the composite.

The catalyst may be prepared by first contacting the mordenite, either synthetic or natural, with dilute acid such as 6 N HCl to lower the alkali metal content of the mordenite to less than 1.0 wt. 70. After washing to remove the acid, the mordenite is mixed with a solution of the compound of the catalytic material for deposition of the catalyst metal on the mordenite. After drying to remove water the metal-impregnated mordenite is contacted with a gel such as alumina gel or a silicaalumina gel and thoroughly mixed and then passed through a colloid mill. The mixture is then formed into particles by pelleting or extrusion. Although a catalyst in which the amorphous inorganic oxide is composed of a mixture of silica and alumina may be used in the process of our invention preferably catalysts containing only alumina in conjunction with the mordenite in the support are preferred since such catalysts are much more selective in the conversion of the charge to a product having a lower pour point.

Not only does the use of the gel in the catalyst preparation result in much more selective conversion but in addition it greatly enhances the crush strength of the catalyst. For example, a catalyst prepared containing only the hydrogenating metal component supported on hydrogen mordenite has a poor crush strength whereas catalysts prepared by adding an oxide gel to the metalimpregnated mordenite have a crush strength of about ten times as great as that of the catalyst containing only EXAMPLE HI hydrogen mordenite in the support. In this example, the same conditions of pressure, The following examples are submitted for illustrative space velocity and hydrogen rate as Examples I and II purposes only: 5 are used. The catalyst differs in that it is prepared by The feed in Examples l, II, III and IV is an Amna gas impregnating preformed pellets of hydrogen form moroil having the following characteristics: denite (silica:alumina mol ratio of :1) with a Pd TABLE I Cl -H Cl solution, drying and calcining. The catalyst composition is 2% palladium on hydrogen mordenite. 10 Average pellet crush strength is 3.5 lbs. Experimental Gravity, API 383 ASTM Dist. F. data are tabulated below:

lo 2ocl 552-563 TABLE 4 0.707, 591. 00 5 Temperature, F. Product Pour Point, F. Yield 9S-EP 640-645 453 +45 876 Pour Point. F. +50 500 +35 75.5 X-Ray Sulfur. wt 7! 0.13 526 -l0 62.3 Normal Paraffins. vol. "/1 32 k High M.S. Analysis (wt/)2 Paraffins 59.6

Cycloparaffns 28.9

lsoparlll'fins 27.6 EXAMPLE Iv Alkvl benzene 3.3

o 8Q Thls example is a substantial duplicate of Example III except that the catalyst contains 0.5 wt. palladium on a hydrogen mordenite support. Average pellet crush strength is 3.3 lbs.

EXAMPLE I In this example, the catalyst is prepared by impreg- TABLE 5 nating hydrogen form synthetic mordenite having an O o alkali metal content of 0.46 wt. 7: and a silicazalumina Temperature Pmduc' Pour Y'eld mol ratio of 14:1 with a Pd Cl H Cl solution. The im- 477 9| 9 pregnated powder is dried at l30-l40F. and then +3 2 mixed with silicazalumina gel, passed through a colloid mill and again dried at l30l40F. After belng 626 0 58.0 crushed to a fine powder, the powder is formed into a paste with water, pelleted, dried and calcined. The final catalyst contains 2.0 wt. 7 palladium, 68 wt. mor- These data Show that the Catalysts composited with the denite and 30 wt. 7( silicaalumina of which the compogel have F higher Strength P profluce sition is 75 wt. silica and 25 wt. alumina. Average Product having a better w -P point relatwnshlp ll t crush th i 32 1b 4 than catalysts in which the support consists of hydrogen Reactant feed is downflow through a fixed bed of catmordenitealyst pellets at 800 psig, 1.0 v/v/hr. space velocity and a hydrogen rate of 7000 SCFB. Results are tabulated EXAMPLE V below: i The charge in this example is a gas oil blend having TABLE 2 the following characteristics:

TABLE 6 Temperature. F. Product Pour Point. F. Yield* Gravity, API 38.7 550 +35 83.5 ASTM Dist 1: 576 lBP-S71 517-549 600 10-20% 561-570 30-407! 578-584 weight "/l basis oil feed 5071 589 -7071 596-605 -907: 616-631 -EP 643-673 EXAMPLE [I 5; Pour Point. F. +45 This example is a substantial duplicate of Example l 6 '5;

except that the catalyst contains 0.5 wt. palladium High Mass Spec Analysis, Wt

and 69.5 wt. 7r mordenite. Average pellet crush g i ff 52.2

yco ara ins strength is 35 lbs. fienz n 3,3 TABLE 3 60 Others 8.5

o o l Tempemwre- Pmduc The catalyst, prepared as described in Example I ex- 550 +40 853 cept that alumina gel is used, has the following compoggg 1:8 3%; 65 sltlon: palladium 2.0 wt. hydrogen mordenite 68 wt. 625 +20 :5 and alumina 30 wt. Average pellet crush strength H v is 38 lbs. Reaction conditions of 800 psig, 1.02 space I velocity and 6000 SCFB hydrogen are maintained while the temperature is varied. Experimental results appear below. I

TABLE 7 Temperature. F. Product Pour Point. F. I Yield EXAMPLE VI The catalyst in this example is similar to that used in Example V and contains 2% palladium, 83% hydrogen mordenite and" 15% alumina by weight. Average pellet crush strength is '37 lbs. The charge stock. an Amna gas oil, has the following characteristics: I

At constant conditions of 800 psig pressure, 1.05 v/v/hr. space velocity and 5970 SCFB hydrogen rate with varying temperatures. the following results are obtained:

TABLE 9 Temperature. F. Product Pour Point. F. Yield EXAMPLE .VII

The catalyst in this example contains 2 weight palladium, 83 weight hydrogen mordenite and alumina prepared as described in Example 1. It has an average pellet crush strength of 45 lbs. The feed is a gas oil having the following characteristics:

TABLE 10 Gravity. AP1 37.x

ASTM Dist. F

lBP-5% 550-565 l0-207r 576-586 30-40% 592-599 50% 605 60-7071 610-618 80-907( 628-642 95-EP 650-660 Pour Point, "F +55 X-RAY Sulfur. Wt 71 0.20

At constant conditions of 800 psig, 1.0 v/v/hr. and a hydrogen rate of 6120 SCFB with varying temperatures,the following results are obtained:

TABLE l-l Temperature, F. Product Pour Point. F. Yield This example is a substantial duplicate ofExample s V11 except that the catalyst contains 0.75 wt. platinum, 84.25 Wt. hydrogen mordenite and 15 wt. alumina. Experimental data appear below:

TABLE 12 Temperature. F. Product Pour Point. 9F. Yield A comparison of the results of Examples VII and VIII show palladium superior'to platinum for the purposes of our invention. Not only does the platinum catalyst show excessive cracking and less selectivity but in addition a much larger percentage of the product is dry gas.

EXAMPLE 1X In this example the same charge is used as in Example V1. Composition of the catalyst is 2.0% palladium. 30% alumina and 68% mordenite which has been leached with hydrochloric acid to a silicazalumina mol ratio of 40:1. Average pellet crush strength is 36 lbs. As in the previous experiments, reactant flow is downward through a fixed bed of catalyst pellets. At conditions of 800 psig, 1.0 space velocity and a hydrogen rate of 5900 SCFB with varying temperatures, the following results are obtained:

TABLE 13 Temperature, F. Product Pour Point. F. Yield EXAMPLE X In this example, the feed is a gas oil having a boiling range of 548-670F., an API Gravity of 378 and a pour point of +55F. The catalyst contains 2% palladium, 15% alumina and 83% mordenite having a silicacalumina mo. ratio of 60:1. Average pellet crush strength is 41 lbs. At reaction conditions of 800 psig, 1.0 space velocity and a hydrogen rate of 6150 SCFB with varying temperatures, the following results are obtained:

TABLE 14 Temperature, F. Product Pour Point Yield The foregoing results show the unsatisfactory results obtained by using mordenite having a silicazalumina mol ratio in excess of 15:] They also show that at temperatures below about 625F. there is a good yield-pour point reduction relationship but that at temperatures above about 625F. there is. as expected, a lower yield but there is not the corresponding lowering of the pour point which would be expected. indicating that there is a selective reaction involving pour point reduction which takes place below about 625F.

It can also be seen that selective pour point reduction takes place when the amorphous inorganic oxide in the support is alumina and is present in an amount between about and by weight based on the catalyst composite.

Obviously, various modifications of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be made as are indicated in the appended claims.

We claim:

1. A process for reducing the pour point of a middle distillate oil which comprises contacting said oil at a temperature between 500F. and 625F. and elevated pressure in the presence of hydrogen with a catalyst consisting essentially of a noble metal on a support containing hydrogen mordenite having a silica alumina mol ratio between 10 and 15:1 and an alkali metal content of less than 1.0 wt. and also containing an amorphous refractory inorganic oxide in an amount between 5 and 50% by weight of the catalyst composite.

2 The process of claim 1 in which the amorphous inorganic oxide comprises alumina.

3. The process of claim 1 in which the noble metal is platinum.

4. The process of claim 1 in which the noble metal is palladium.

5. The process of claim 1 in which the pressure is between 750 and 3000 psig.

6. The process of claim 1 in which the noble metal is present in an amount between 0.1 and 5.0% by weight of the catalyst composite. K

7. The process of claim 1 in which the amorphous refractory inorganic oxide is present in an amount between l0 and 40% by weight of the catalyst composite.

8. The process of claim 1 in which the catalyst is prepared by impregnating hydrogen mordenite with a solution containing a nobel metal, adding an inorganic oxide gel to the impregnated mordenite, intimately mixing the resulting product and forming the mixture into catalyst particles.

9. The process of claim 8 in which the gel is an alumina-silica gel.

10. The process of claim 8 in which the gel is alumina gel.

Claims

1. A PROCESS FOR REDUCING THE POUR POINT OF A MIDDLE DISTILLATE OIL WHICH COMPRISES CONTACTING SAID OIL AT A TEMPERATURE BETWEEN 500*F. AND 625*F. AND ELEVATED PRESSURE IN THE PRESENCE OF HYDROGEN WITH A CATALYST CONSISTING ESSENTIALLY OF A NOBLE METAL ON A SUPPORT CONTAINING HYDROGEN MORDENITE HAVING A SILICA ALUMINA MOL RATIO BETWEEN 10 AND 15:1 AND AN ALKALI METAL CONTENT OF LESS THAN 1.0 WT.% AND ALSO CONTAINING AN AMORPHOUS REFRACTORY INORGANIC OXIDE IN AN AMOUNT BETWEEN 5 AND 50% BY WEIGHT OF THE CATALYST COMPOSITE.

2. The process of claim 1 in which the amorphous inorganic oxide comprises alumina.

3. The process of claim 1 in which the noble metal is platinum.

4. The process of claim 1 in which the noble metal is palladium.

5. The process of claim 1 in which the pressure is between 750 and 3000 psig.

6. The process of claim 1 in which the noble metal is present in an amount between 0.1 and 5.0% by weight of the catalyst composite.

7. The process of claim 1 in which the amorphous refractory inorganic oxide is present in an amount between 10 and 40% by weight of the catalyst composite.

9. The process of claim 8 in which the gel is an alumina-silica gel.

10. The process of claim 8 in which the gel is alumina gel.