GB1601655A

GB1601655A - Catalytic dewaxing with a hydrogen form zeolite l catalyst

Info

Publication number: GB1601655A
Application number: GB11647/78A
Authority: GB
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1977-03-28
Filing date: 1978-03-23
Publication date: 1981-11-04
Also published as: JPS621991B2; CA1117457A; IT1094200B; FR2385788A1; JPS546A; DE2812941A1; DE2812941C2; NL7803180A; FR2385788B1; IT7821572A0; MX148176A

Description

(54) CATALYTIC DEWAXING WITH A HYDROGEN FORM ZEOLITE L CATALYST (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and exisiting under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: BACKGROUND OF THE INVENTION 1. Field of the invention This invention relates to the selective conversion of hydrocarbons, particularly of waxy, normal paraffin type hydrocarbons present in hydrocarbon oil feedstocks, to lower boiling hydrocarbons.

2. Description of the prior art It is well known in the art to dewax wax-containing mineral oils, particularly the lube oil fractions of petroleum oil, in order to remove gt least a portion of the wax therefrom to obtain a dewaxed oil of reduced pour point. For many years this wax has been removed via various solvent dewaxing processes.

Concomitant with the worldwide decreasing supply of naphthenic crudes heretofore used to make very low pour point oils such as transformer oils, there has been an increase in the demand for these oils due to the continuously increasing demand for electrical power.

Transformer oils used in colder climates generally have a pour point requirement of around -500F. It is technologically unfeasible to obtain these low pour transformer oils via solvent dewaxing of paraffinic oils, because of the extremely severe refrigeration requirements.

White oils are highly refined petroleum oils which must meet various requirements including haze-free water whiteness and are generally produced from naphthenic stocks which sometimes contain around 1 or 2% wax. This wax can affect the pour point of the oil and results in a haze which is cosmetically objectionable. It is also technologically unsound to solvent dewax these white oils. Certain middle distillate fuels must also have low pour points so that the fuels do not congeal at low temperatures. This is especially true for jet fuels.

In recent years, various catalytic dewaxing processes have been proposed. Catalytic processes for dewaxing wax-containing hydrocarbon oils wherein the normal paraffinic wax constituents contained therein are broken into lower molecular weight olefins and gases using crystalline aluminosilicate zeolites such as offretite, chabazite, Zeolite A, analcite, erionite and mordenite have been disclosed. However, when higher boiling fractions such as lube oil fractions are catalytically dewaxed using catalysts such as erionite, coke very quickly builds up on the catalysts thereby deactivating them.

More recently, it has been found that mordenite, particularly the hydrogen form of mordenite commonly referred to in the art as decationized or H-mordenite, and certain ZSM-type crystalline alumino-silicates are effective in catalytically dewaxing the heavier petroleum oil fractions such as lube oil fractions. These zeolites preferably contain a hydrogenation component selected from one or more Group VI and VIII metals and oxides thereof. The wax-like hydrocarbons, particularly the normal paraffin types, are selectively hydrocracked into lower boiling hydrocarbons which are primarily gases at room temperature, thereby producing a dewaxed oil product having a substantially lower wax content and pour point.

Additionally, a method has been disclosed for regenerating H-mordenite as well as possibly other zeolites such as Zeolite Y, T, L, erionite and offretite when such zeolites have been deactivated during a catalytic dewaxing process.

The prior art teaches that various other types of crystalline alumino-silicates are not suitable for use in catalytic dewaxing processes and in particular discloses that large pore size crystalline alumino-silicates or zeolitic molecular sieves represented by zeolites of type X, Y and L, which admit all components normally found in petroleum distillate charges are unsuitable for use in catalytic dewaxing or h drodewaxing processes and that only those which have a pore size of approximately 5 A are suitable because they will admit only normal and/or slightly branched paraffins present in a hydrocarbon feed charge.

SUMMARY OF THE INVENTION A process for catalytically dewaxing waxy hydrocarbons from wax-containing hydrocarbon oil feedstocks has now been discovered, which comprises contacting said feedstock at elevated temperature and pressure and in the presence of hydrogen with a catalyst comprising a hydrogen form Zeolite L molecular sieve or crystalline alumino-silicate and recovering an oil product having a reduced wax content. In the process of this invention, waxy hydrocarbons present in the feedstock are selectively hydrocracked to hydrocarbons boiling below the boiling range of the feedstock. If the Zeolite L is not at least partially decationized and converted to the hydrogen form it will not work effectively in the process of this invention. It is preferred that the hydrogen form Zeolite L contain one or more catalytic metal components selected from the Group VI and Group VIII metals of the Periodic Table, their oxides, sulfides and mixtures thereof. It has further been discovered that the selectivity of the decationized Zeolite L for hydrocracking wax is greatly improved if the external surface of the sieve is poisoned or made catalytically inactive. It has still further been discovered that the process of this invention simultaneously reduces the aromatics content of the feed.

Crystalline alumino-silicates of the Zeolite L type are well known. These materials are characterized in that they have a one-dimensional channel system parallel to the C - axis with a calculated free aperture size of about 7.1 . U.S. Patent 3,216,789 discloses the composition, characterization and preparation of Zeolite L types of crystalline aluminosilicates. Zeolite L has a general formula as follows: 0.9 - 1.3M2 O:Al203:5.2 - 6.9 SiO2:yH2O n -u Wherein "M" designates at least one exchangeable cation hereinbelow defined; rt, represents the valence of "M"; and "may may be any value from 0 to about 9. Further, the value of "y" depends upon the identity of the exchangeable cations and also upon the degree of dehydration of the zeolite.

The exchangeable cations that may be present in Zeolite L include mono-, di- and trivalent ions, particularly those of Groups I, II and III of the Periodic Table, such as potassium sodium, barium, calcium, cerium, magnesium, lithium, strontium and zinc ions, inter alia, and other cations for which example hydrogen, ammonium and alkyl-ammonium ions, which with Zeolite L behave like the metal ions mentioned above in that they may be replaced for other exchangeable cations without causing a substantial alteration of the basic crystal structure of the zeolite. However, although there are a number of cations that may be present in Zeolite L, in the commercially available form substantially all of the exchangeable cations are potassium ions.

As stated the synthesis of the Zeolite L catalyst is well known in the art. For example, the zeolite may be crystallized from a suitable aqueous metal alumino-silicate mixture at temperatures ranging from 20 to 175"C.

Zeolite L will not selectively hydrocrack wax from petroleum oil stocks, such as white oil, jet fuel or lube oil stocks, unless it is decationized and converted to the hydrogen form. By decationization and conversion to the hydrogen form is meant that the exchangeable metal cation, such as potassium, is at least partially replaced with hydrogen. Preferably at least about 10%, more preferably from about 15 to 75% and still more preferably from about 40 to 60% of the exchangeable metal cations in the sieve have been exchanged with hydrogen ion to produce the hydrogen form Zeolite L useful in this invention. The attached Figure is a graph illustrating the hydrodewaxing activity of a Zeolite L catalyst as a function of the replacement of potassium with hydrogen in the sieve. It has been found that, in general, the activity or ability of the Zeolite L catalyst to dewax the oil increases with increasing replacement of potassium with hydrogen in the sieve, reaching a maximum between about 40 to 50%. Methods for replacing the metal cations with hydrogen are well known in the art. Various methods of decationizing Zeolite L and converting it to the hydrogen form are described in U.S. Patent 3,130,006. The decationization treatment is preferably carried out by base exchanging a metal cation form of Zeolite L, such as the potassium form, with ammonium cations. The ammonium-ion exchanged molecular sieve is then heated to drive off ammonia, leaving behind the decationized or hydrogen form of Zeolite L.

As hereinbefore described, it is preferred that the hydrogen form Zeolite L contain one or more metal hydrogenating components selected from the Group VI and Group VIII metals, their oxides, sulfides and mixtures thereof. Preferably, the catalytic metal component of the catalyst is a platinum group metal, particularly platinum or palladium, and may be added by any of the well known methods such as ion-exchange or impregnation.

The amount of platinum group metal added to the catalyst is preferably within the range of from 0.05 to 10 wt. %, more preferably 0.1 to 5 wt. % and most preferably 0.2 to 2.0 wt. % calculated as metal and based on the total weight (dry basis) of the catalyst. Iron group metals such as nickel also give useful results and they may be used in greater amounts than the platinum group metals, preferably within the range of 0.1 to 50 and more preferably 1.0 to 20.0 wt. % calculated as metal and based on the total weight (dry basis) of the catalyst., Mixtures of certain Group VI and Group VIII metals and compounds may also be used, for example, such as cobalt and molybdenum. Further, it may be advantageous to incorporate into the catalyst multivalent metals of Groups II and III in addition to one or more metals of Groups VI and/or Group VIII.

As hereinbefore mentioned, it has also been discovered that still further improvements in the catalytic dewaxing process of this invention may be realized if the external exposed surfaces of the catalyst are poisoned. Any well known methods may be employed such as coke deposition or treatment with heavy metal or basic compounds. However, a preferred method is by treatment with an organic phosphorous compound capable of inhibiting the catalytic activity thereof and of such molecular size and shape as to be excluded from entering the pores in the catalyst and making contact with the active catalytic sites in the pores. That is, greater selectivity in catalytic dewaxing resulting in higher yields of dewaxed oil will be realized if the outer surface of the catalyst is poisoned and not the surfaces inside the pores, so that only the wax-like normal paraffins and perhaps the slightly branched normal paraffin hydrocarbons which can enter the pores are hydrocracked therein. The other molecules and molecular species which are too large to enter the pores will not be cracked if the external surface of the catalyst is poisoned. Suitable organic phosphorous compounds useful as poisoning media for the external catalytic sites of the Zeolite L include organic and particularly cyclic phosphates, phosphites, phosphonates, phosphonites, and phosphines. Typical of such compounds are the dibenzylphosphates, dibenzylphosphites, dibutylphenylphosphonites, diphenylmethylphosphates, diphenylphenylphosphonites, diphenylphosphites, dicresylphosphites, ethylene(bis) diphenylphosphines, ethylene(bis)diphenylphosphine oxides, naphthylphosphates, triphenylphosphines, triphenylphosphine oxides, triphenylphosphates, triphenylphosphites, tri(dimethylphenyl) phosphates, and tricresylphosphates, with tricresylphosphates being particularly preferred.

Poisoning of the external surface of the catalyst may be accomplished by addition of the organic phosphorous-containing poison compound to the charge stream prior to contacting with the catalyst. Alternatively, it may be desirable to contact the catalyst with a suitable poisoning compound prior to bringing the same into contact with the charge stock. In some instances, it may be feasible to contact the catalyst simultaneously with the poisoning compound, and the charge stock. Pretreating the catalyst with the poisoning compound may be accomplished by contacting particles of the catalyst with the poisoning material or a suitable solution containing an amount of such material sufficient to poison the exterior catalytic sites of said catalyst. The particles are thereafter removed from contact with the poisoning material or solution thereof and dried.

Suitable catalytic dewaxing process conditions include temperatures within the broad range of 450 to 950OF., preferably 500 to 8500F. and still more preferably 500 to 7500F., hydrogen pressures within the range of 100 to 5000 psig, preferably in the range of 200 to 2500 psig and most preferably from 400 to 1500 prig, a space velocity between 0.1 to 20 liquid volumes per hour per volume of catalyst (v/h/v), preferably 0.25 to 5.0 v/h/v, and hydrogen feed rates in the range of 0 to 20,000 SCF/B, more preferably 500 to 10,000 SCF/B and most preferably 1000 to 8000 SCF/B.

Almost any wax containing synthetic or petroleum oil feedstock or distillate fraction thereof which has been deasphalted may be catalytically dewaxed employing the process of this invention. Illustrative, but nonlimiting examples of such feedstocks are the middle distillate fractions, such as jet fuel boiling within the broad range of 300 to 650OF., and lube oil stocks such as (A) distillate fractions that have a boiling range within the broad range of from about 500 to 1300OF., with preferred stocks including the lubricating oil and specialty oil fractions boiling above 500OF, preferably within the range of between about 550 and 1200OF., and (B) bright stocks and deasphalted resids having an initial boiling point above about 800OF. Additionally, any of these feeds may be hydrocracked prior to the catalytic dewaxing process of this invention. These stocks may come from any source such as the paraffinic crudes obtained from Aramco, Kuwait, the Pan Handle, North Louisiana, etc., the naphthenic crudes obtained from Venezuela, the U.S. Gulf Coast, Cold Lake (Alberta), etc., as well as synthetic crudes derived from the Athabasca Tar Sands, etc.

BRIEF DESCRIPTION OF THE DRAWING The attached drawing is a graph illustrating the catalytic dewaxing activity of a Zeolite L catalyst as a function of the amount of potassium ions in the sieve that have been replaced with hydrogen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples further illustrate the present invention.

Example I Zeolite L in the potassium cation form was obtained from the Linde Division of the Union Carbide Corp. designated as K-L Linde (hereinafter referred to as Zeolite K-L) having the unit cell composition shown below K8Na0, 15(AlO2)8,4(SiO2)27, X H20 The Zeolite K-L was supplied as a powder. In its anhydrous mode (i.e., dried at about 1000OF.) Zeolite K-L has a potassium content of 13 wt. %. However, if it is dried at about 250OF. it has a potassium content of 12 wt. % due to the presence of some water of hydration in the sieve. Sixty grams of the catalyst were treated with one liter of an aqueous 0.4 molar ammonium nitrate solution at reflux temperature for eight hours followed by calcination in air at 1000OF. for two hours to produce a partially decationized Zeolite K-L (hereinafter referred to as Zeolite HK-L) in which about 20% of the potassium ions initially present in the sieve were replaced with hydrogen ions. The powder was pressed into a cake, crushed and sieved into 7 to 14 mesh size particles which were used as catalysts in this experiment. Palladium was deposited on both the Zeolite HK-L and Zeolite K-L by soaking the catalyst particles in an aqueous, mildly acid palladium chloride solution containing sufficient palladium to produce a catalyst containing 0.25 wt. % palladium. The palladium containing catalysts were then calcined in air at 900 to 1000OF. for two hours and reduced in a stream of hydrogen at 650OF. for six hours. Wax-containing lube oil feedstock comprising solvent extracted paraffinic distillates having the properties shown in Table I were passed over the catalysts in the presence of hydrogen. The catalytically dewaxed product was then stripped to remove material boiling below 500OF. The results listed in Table I show that the Zeolite K-L which was not decationized or partially converted to the hydrogen form was ineffective in reducing the wax content as reflected in the pour point, whereas the decationized Zeolite HK-L removed a considerable amount of wax as reflected in the low pour points of -20 and -270F.

Example 2 In this example the effectiveness of the decationized or hydrogen form Zeolite HK-L from Example 1 was compared with decationized or H-mordenite known in the art as an effective catalyst for dewaxing lube oil fractions. Before the catalysts were used for catalytic dewaxing, the surface active sites were poisoned to see if there would be any improvement in catalyst selectivity. The catalysts were soaked in a 10 wt. % solution of tricresylphosphate (TCP) in n-heptane for a number of hours. The TCP treated catalysts were washed with heptane in order to remove any excess therefrom and then placed in reactors and heated in the presence of hydrogen to the reaction temperature at which point the liquid feed was cut in. The same type of lube oil feeds used in Example 1 was also used in this experiment.

The results are in Table II and show that compared to the H-mordenite, not only did the Zeolite HK-L produce a much higher yield of dewaxed product at a comparable reduction in pour point, but it did so with no significant loss in VI, thereby illustrating that decationized Zeolite L can be used for catalytically dewaxing lube oil base stocks without the need for a prior or subsequent treatment to boost the VI which the art teaches is necessary when using H-mordenite.

The beneficial effect of the TCP treatment is reflected in the much superior selectivity of the treated catalyst. This is seen by comparing the data in Tables I and II at 5760F. for both the TCP treated and untreated Zeolite HK-L. Thus, the treated Zeolite HK-L produced a product yield of 89 wt. % of feed compared to 50.1 wt. % for the untreated Zeolite HK-L.

Example 3 This example illustrates the effect of catalyst activity as a function of replacing potassium ions in the Zeolite K-L sieve with hydrogen ions. The waxy feed was similar to that used in Examples 1 and 2 and had a pour point of +7OF. The Linde Zeolite K-L was treated according to the following procedure.

(a) 60 g. of catalyst base were treated with one liter of NH4C1 solution under reflux.

Solution strength varied from 0.05N (normal) to 2N depending on the amount of potassium removed and replaced with hydrogen. For the case where 72% of the potassium ions were replaced with hydrogen ions, the catalyst base was given two treats with 2N NH4C1 solution.

(b) The treated base was calcined in air at 10000F. for two hours to convert the NH4+ to H+ and the base was then pressed into pellets.

(c) The pellets were treated by soaking in a solution of PdC12 in a low concentration (i.e., < 0.5N) HCI solution to impregnate the sieve with palladium so that the catalyst contained 0.25 wt.% Pd based on the total catalyst weight (dry basis).

(d) The Pd impregnated sieve was washed in water, dried at 248OF. and then calcined for one hour at 932OF.

(e) The calcined catalyst was then reduced in hydrogen at 7520F. to produce a finished catalyst. The waxy feed was passed over the catalyst at a liquid hourly space velocity of 1.0' V/h/V, at a hydrogen pressure of 600 psig and at temperatures of 550 and 575OF.

The results are plotted in the Figure which is a graph of catalyst activity as a function of potassium ion replacement with hydrogen ion. By activity is meant wax removal of dewaxed product (stripped to an initial boiling point of 500OF.) as reflected in pour point. It is apparent from the Figure that catalyst activity increases with increasing replacement of potassium ions with hydrogen ions, reaching a maximum between about 40 to 50% replacement. It is also obvious that for practical dewaxing activity at least about 10 to 15% of the potassium ions should be replaced with hydrogen ions.

TABLE I Catalyst Base Zeolite K-L Zeolite HK-L Catalyst Metal 0.25% Palladium 0.25% Palladium Reaction Conditions* Temperature, "F 650 550 576 Inspections Feed Product * Feed Product** Yield, wt.% 100 90 100 73.5 50.1 Pour, "F -5 1 3 -20 -27 Viscosity, cSt &commat; 100OF 19.6 19.5 19.1 18.8 16.8 Viscosity Index 94 - 92 90 * Other conditions include H2 pressure of 1350 psig, liquid hourly space velocity (LHSV) of 0.5 VlhlV (volumes of feed per hour per volume of catalyst) and a hydrogen gas rate of 2000 SCF/B (standad cubic feet per barrel of feed).

** Product stripped to 5000F+.

TABLE II TCP Treated Zeolite HK-L TCP Treated H-Mordenite Catalyst Metal 0.25% Palladium 0.5% Palladium Reactor Temperature. F* 576 601 525 576 Product Inspections Feed Product* Feed Product** Yield, wt.% 100 89 83 100 68 45 Pour, "F 3 -11 -29 1 -35 -40 Viscosity, cSt &commat; 100OF 19.1 16.7 17.9 19.3 29.6 42.7 Viscosity Index 92 90 89 - 73 45 * Other conditions are those in Table I.

** Products stripped to 500OF+.

Example 4 This example illustrates the ability of the hydrogen form Zeolite L dewaxing catalyst to simultaneously reduce both aromatics and wax content. About 20% of the potassium ions present in the Zeolite K-L sieve were replaced with hydrogen ions via treatment with 0.5N NH4CI for two hours on a steam bath. The treated sieve was washed free of excess salt and then calcined at 10040F for two hours to produce Zeolite HK-L. The Zeolite HK-L was then pressed into a cake, crushed and sieved. Palladium deposition, calcining and reduction of the catalyst were then carried out via the procedure used in Example 1. This experiment used the same type of feed as in Example 1.

The results are shown in Table III and are compared to results obtained from using H-mordenite. Thus, not only did the Zeolite HK-L catalyst reduce the wax content and pour point lower than that obtained with H-mordenite, it simultaneously produced a dewaxed product having an aromatics content substantially lower than that of the feed.

TABLE III Simultaneous dewaxing and reduction in aromatics content Catalyst Base H-Mordenite Zeolite HK-L Catalyst Metal 0.5% Platinum 0.25% Palladium Reactor Conditions Temperature, "F 500 550 Pressure (psig H2) 1350 1350 LHSV V/h/V 1.0 1.0 Gas Rate, SCF/B 5000 5000 Inspections Feed Product* Feed Product* Pour, "F 1 -15 7 -22 Yield, wt.% 100 89 100 77 Viscosity &commat; 100OF (cSt) 18.7 22.0 19.1 20.6 Viscosity Index 92 81 93 92 Mass Spec Analysis (Total Oil) Saturates, LV% 87.0 86.1 87.6 91.8 Aromatics, LV% 13.0 13.9 12.4 8.2 * Products stripped to 500OF+.

Example 5 This example illustrates the fact that the process of this invention selectively hydrocracks waxy hydrocarbons to lower boiling hydrocarbons. In this experiment the feed was a wax boiling in the range of from 572 to 968OF. which was derived from a Western Canadian crude oil. The hydrogen form Zeolite L catalyst was prepared by boiling Linde Zeolite K-L in powder form for two hours in a 2 normal NH4Cl solution. The treated sieve or catalyst base was then washed with water after which 0.5 wt. % palladium was added by ion exchange with a Pd(NH3)4Cl2 solution at a pH of 10. The ion-exchanged sieve was then washed with water and calcined in air for two hours at a temperature of 752OF. After calcining the catalyst was pelletized and treated with hydrogen for six hours at a temperature of about 572OF. to produce a finished catalyst. Analysis revealed that about 44% of the potassium ions remained in the sieve.

Two runs were made at a temperature of 550OF. and a pressure of 600 psig of hydrogen.

The first run was made at a space velocity of 1.0 V/hr/V and the results are shown in Table IV. The second run was made under a more severe space velocity of 0.5 V/hr/V. In the second run all of the wax feed was converted to hydrocarbons boiling below the initial boiling point of the feed (572OF.) with a substantially greater amount of gaseous product formed than in the first run.

Turning to Table IV, the data show that under the less severe hydrocracking conditions over 50% of the wax was hydrocracked to lower boiling hydrocarbons boiling below the initial boiling point of the wax feed. Also under the less severe hydrocracking conditions only 2.7 wt. % of the feed wax was converted to oil (per ASTM D 721) boiling in the same range as the feed wax.

These data and the data from the other examples show that the reaction of the present invention is selective hydrocracking and that very little isomerization of the wax took place.

TABLE IV Zeolite L selectivity for wax cracking Distribution by Carbon Number, Wt. % Feed* Product C1 O C2 o C3 2.3 C4 9.4 C5 9.7 C6+C7 14.0 C8 to C12 24.4 C12 to C21 0.3 6.3 C22 0.8 0.2 C23 2.8 0.9 C24 6.5 2.2 C25 10.7 3.7 C26 13.8 4.8 C27 13.8 4.8 C28 12.8 4.5 C29 11.3 4.0 C() 8.7 3.0 C31 6.9 2.4 C32 4.7 1.6 C33 3.0 1.0 C34 1.9 0.6 C35 1.0 0.3 C36 0.5 C37 0.3 C38 0.2 Note: * Paraffin Wax WHAT WE CLAIM IS: 1. A process for catalytically dewaxing a wax-containing hydrocarbon oil comprising contacting said oil at elevated temperature and pressure and in the presence of hydrogen with a catalyst comprising a hydrogen form Zeolite L crystalline alumino-silicate and recovering an oil having a reduced wax content.

2. A process according to claim 1 in which the said catalyst contains one or more catalytic metal components selected from the Group VI and Group VIII metals, their oxides, sulfides and mixtures thereof.

3. A process according to claim 1 or claim 2 in which at least about 10% of the exchangeable cations in said Zeolite L have been replaced with hydrogen.

4. A process according to claim 2 or claim 3 in which the said catalytic metal component is an iron group metal and is present in said catalyst in an amount in the range of from 0.1 to 50 wt. % of the catalyst.

5. A process according to claim 2 or claim 3 in which the said catalytic metal component is a platinum group metal and is present in said catalyst in an amount in the range of from 0.05 to 10 wt. % of said catalyst.

6. A process according to any one of claims 2, 3 or 5 in which said catalytic metal component is platinum or palladium.

7. A process according to any one of claims 1-6 in which the external surface of said catalyst has been poisoned with an organic phosphorous compound or coke.

8. A process according to any one of claims 1-7 in which the said oil contains aromatic components and wherein said process simultaneously reduces the aromatics content of said oil.

9. A process according to any one of claims 1-8 in which the said elevated temperature and pressure are in the respective ranges from 450 to 9500F. and from 100 to 5000 psig.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. These data and the data from the other examples show that the reaction of the present invention is selective hydrocracking and that very little isomerization of the wax took place. TABLE IV Zeolite L selectivity for wax cracking Distribution by Carbon Number, Wt. % Feed* Product C1 O C2 o C3 2.3 C4 9.4 C5 9.7 C6+C7 14.0 C8 to C12 24.4 C12 to C21 0.3 6.3 C22 0.8 0.2 C23 2.8 0.9 C24 6.5 2.2 C25 10.7 3.7 C26 13.8 4.8 C27 13.8 4.8 C28 12.8 4.5 C29 11.3 4.0 C() 8.7 3.0 C31 6.9 2.4 C32 4.7 1.6 C33 3.0 1.0 C34 1.9 0.6 C35 1.0 0.3 C36 0.5 C37 0.3 C38 0.2 Note: * Paraffin Wax WHAT WE CLAIM IS:

1. A process for catalytically dewaxing a wax-containing hydrocarbon oil comprising contacting said oil at elevated temperature and pressure and in the presence of hydrogen with a catalyst comprising a hydrogen form Zeolite L crystalline alumino-silicate and recovering an oil having a reduced wax content.

10. A process according to any one of claims 1-9 in which said oil is a synthetic or

petroleum oil fraction selected from (a) middle distillate fractions boiling within the range of 300 to 650OF. and (b) lubricating and specialty oil fractions having an initial boiling point above 500OF.

11. A process for catalytically dewaxing a wax-containing hydrocarbon oil substantially as hereinbefore described with particular reference to Examples 1 to 4 and the drawing.

12. A process according to any one of claims 1 to 11 substantially as hereinbefore described.

13. A dewaxed oil whenever produced by the process of any one of claims 1-12.