NO831715L - PROCEDURE FOR CRACKING AND DEVICING A HEAVY HYDROCARBON OIL. - Google Patents

Description

The present invention relates to a method for catalytic hydrocracking and hydrodewaxing of a hydrocarbon starting material to produce distillates with a low solidification point and heavy fuel oils with reduced viscosity.

Catalytic dewaxing of carbon oils to reduce the temperature at which a separation of waxy hydrocarbons takes place is a known method. A method of this type is i.a. described in The Oil and Gas Journal dated January 6, 1975, pages 69-73. Furthermore, US patent 3,668,113 and US patent 3,894,938 also describe a dewaxing

followed by a hydro-finishing treatment.

Reissue Patent No. 28,398 discloses a. method for catalytic dewaxing with a catalyst consisting of a zeolite of the ZSM-5 type. A hydrogenation/dehydrogenation component may be present.

A method for hydrodewaxing a gas oil with a

ZSM-5 type catalyst is described in US patent 3,956,102.

A mordenite catalyst containing a Group VI or Group VII metal of the periodic table used for dewaxing a low V.I. distillate from a waxy starting material is described in US Patent 4,110,056.

US Patent 3,755,138 describes a process for mild solvent dewaxing to remove high quality wax from a lubricating oil feedstock, which is then catalytically dewaxed to a specific pour point.

US patent 3,923,641 describes a method for hydrocracking naphtha where a zeolite beta is used as catalyst.

Hydrocracking is a well-known method and various zeolite catalysts have been used in hydrocracking processes of this type, but although said catalysts can effectively provide distillate yields that have one or more properties in accordance with the assumed use of the distillate, these catalysts generally have had the disadvantage that they have not given products with good low-temperature fluidity properties, as especially reduced solidification point and viscosity. The catalyst used for hydrocracking consists of an acid component and a hydrogenation component. The hydrogenation component can be a noble metal, such as platinum or palladium or a non-noble metal, such as nickel, molybdenum or tungsten or a combination of these metals. The acid cracking component may be an amorphous material, such as an acid clay or amorphous silica-alumina, or alternatively a zeolite. Large-pore zeolites such as zeolite X and Y have been appropriately used for this purpose because the main components of the starting materials: (gas oils, coke bottom fractions, reduced crude oils, recycled oils, FCC well fractions) are high molecular hydrocarbons that do not penetrate into the inner pore structure of small-pore zeolites and therefore will not be converted. Thus, if waxy starting materials such as Amal gas oil are hydrocracked with a large-pore catalyst, such as zeolite Y in combination with a hydrogenation component, the viscosity of the oil will be reduced by cracking most of the 343°C+ material into compounds boiling between 34 3 and 165°C .

The remaining part of the 34 3°C+ material which is not converted contains the main amounts of the paraffinic components in the starting material, because the aromatic compounds are preferentially converted into paraffins. The unconverted 34 3°C+ material therefore retains a high solidification point, so that the final product will also have a relatively high solidification point of approx. 10°. Although the viscosity can thus be reduced, the solidification point is still unacceptable. Even if the conditions are adjusted so that one gets a complete or almost complete transformation, so

the high molecular weight carbons present in the starting material, which are in principle polycyclic aromatic compounds, will be subjected to cracking leading to

further reductions of the product's viscosity. The cracking products will, however, contain a significant proportion of straight-chain components (n-paraffins), which if they have a sufficiently high molecular weight in themselves, which is often the case, constitute a waxy component in the product. The end product may therefore contain proportionally more wax than the starting material, and consequently have a solidification point that is even more unsatisfactory than in the starting material. A further disadvantage of using high conversion conditions is that the consumption of hydrogen increases. Attempts to reduce the molecular weight of these straight-chain paraffinic products will only give very light fractions, e.g. propane, thereby reducing the desired liquid yield.

in

In a waxing process, on the other hand, you often want to

use a small-pore zeolite or a selectively formed zeolite such as ZSM-5 as the acid component of the catalyst, and the normal or slightly branched paraffins present in the starting material will be able to penetrate into the zeolite's internal pore structure and be converted there. The bulk, typically up to 70% of the starting material, which boils above 34 3°C will remain unconverted because the larger volumes and their aromatic components, especially polycyclic aromatic compounds, will not be able to penetrate the zeolite. The paraffinic waxy components will consequently be removed so as to lower the product's solidification point, while the other components remain in the product so that it has an unacceptably high viscosity even if the solidification point is satisfactory.

It has now been found that heavy hydrocarbon oils can be simultaneously hydrocracked and dewaxed, whereby a liquid product with a satisfactory solidification point and viscosity is produced. This desirable result is achieved by using a catalyst

which contains zeolite beta as an acid component to induce cracking reactions. The catalyst preferably includes a hydrogenation component to induce hydrogenation reactions. This hydrogenation component can

be a precious metal or a non-precious metal, and is suitable of a commonly known type, e.g. of nickel, tungsten, cobalt, molybdenum or combinations of these metals.

The present invention therefore provides a method for cracking and dewaxing a heavy hydrocarbon oil,

and where the method includes contacting the oil with a catalyst that includes zeolite beta.

In the present process, the hydrocarbon feedstock is heated with the catalyst under conversion conditions suitable for hydrocracking. During this conversion, aromatic compounds and naphthenes present in the starting material will undergo hydrocracking reactions such as dealkylation, ring opening and cracking followed by hydrogenation. The long-chain paraffins that may be present in the starting material together with the paraffins produced by the hydrocracking of the aromatic compounds will also be converted into products that are less waxy than the aforementioned straight-chain N-paraffins, thereby simultaneously obtaining an effective dewaxing. The use of zeolite beta seems to be unique in this respect, as you not only get a reduction of the product's viscosity with the help of said hydrocracking, but you also get a simultaneous reduction of the solidification point with the help of a catalytic dewaxing.

The present method makes it possible to convert heavy starting materials such as gas oils that boil above 34 3°C into distillate products that boil below said temperature, but unlike previously known methods where large-pored catalysts such as zeolite Y were used, the amount of hydrogen will be reduced although the product will meet the desired specifications with regard to pour point and viscosity. In contrast to awoxing processes where form-selective catalysts such as zeolite ZSM-5 are used, the main conversion will also include a cracking of aromatic components, which thus ensures an acceptably low viscosity of the distillate products. The present method is thus capable of effectively carrying out a head conversion at the same time as a simultaneous dewaxing. This is further achieved with a reduced hydrogen consumption compared to previously known methods. It is also possible to achieve a partial conversion, which effectively affects the economy in terms of hydrogen consumption while achieving the desired requirements in terms of solidification point and viscosity. The method also achieves improved selectivity for the production of compounds in the distillate range, as a reduced yield of gas and products boiling below said distillate range is obtained.

As mentioned above, the process includes elements of hydrocracking and dewaxing. The catalyst used in the process has an acidic component and a hydrogenation component which can be of the usual type. The acidic component includes a zeolite beta which is described in US Patents 3,303,069 and Re 28,341 and reference is made to these patents for details regarding said zeolite and its preparation.

Zeolite beta is a crystalline aluminum silicate zeolite with

a pore size of more than 5 Angstroms. The composition of the zeolite as described in US patents 3,303,069 and Re 28,341 can be expressed in its synthesized form as follows:

where X is less than 1, preferably less than 0.7; TEA represents the tetraethylammonium ion; Y is greater than 5 but less than 100 and W is up to 60 (it has been found that

the degree of hydration may be higher than originally determined where W was defined as a maximum of 4), depending on the degree of hydration and the metal cation present.

The TEA component is calculated by the differences between the analyzed value for sodium and the theoretical cation-to-structural aluminum ratio in the unit.

In the fully base-extracted form, beta has the following composition:

where X, Y and W have the values given above, and n is the valence of the metal M. i: the partially base substituted form obtained from the original sodium form of the zeolite by ion exchange but without calcination, zeolite has beta following formula:

When the zeolite is used in catalysts it is at least partially in the hydrogen form to thereby provide the desired acid functionality for the cracking reactions that take place. It is normally preferred to use the zeolite in a form which has sufficient acidic functionality to give an alpha value of 1 or more. The alpha value, which is a measure of the acid functionality of the zeolite, is described, along with details of its measurement, in US Patent 4,016,218 and in J.Catalysis, Vol VI, pages 278-287 (1966) and reference is made to these publications for further details. Said acid functionality can be regulated by the base yield of the zeolite, especially with alkali metal cations such as sodium, by steam treatment or by regulating the silicon dioxide:alumina ratio in the zeolite.

When it is synthesized in the alkali metal form, zeolite beta can be converted to the hydrogen form by first forming the intermediate ammonium form as a result of an ammonium ion yield and a calcination of said ammonium form will then give the hydrogen form. In addition to the aforementioned hydrogen form, other forms of the zeolite can also be used where the original alkali metal content has been reduced to less than approx.

1.5% by weight. The original alkali metal in the zeolite can thus be replaced by ion exchange with other suitable metal cations, e.g. nickel, copper, zinc, palladium, calcium and rare earth metals.

Zeolite beta, in addition to having a composition as defined above, can also be characterized by its X-ray diffraction data as set forth in US Patents 3,308,069 and Re 28,341.

The significant d values (Angström, irradiation: K alpha doublet in copper, Geiger counter spectrometer) are shown in table 1 below:

The preferred forms of zeolite beta for use in the present process are forms with a high silicon dioxide content,

and having a silica:alumina ratio of at least 30:1. In fact, it has been found that zeolite beta can be prepared with a silica:alumina ratio in excess of the maximum of 100:1 set forth in US Patents 3,308,069 and Re 2 9,341, and these forms of the zeolite give the best results in the present method.

One can use ratios of at least 50:1 and preferably at least

100 : 1 or even higher, e.g. 250:1 or 500:1.

The silicon dioxide : aluminumoxy ratio referred to here is the framework ratio or the structural ratio, i.e. the ratio between Si04 to Al04~ tetrahedra which together form the lattice of which the zeolite is composed. It is understood that this ratio may vary from the silica:alumina ratio determined by various physical and chemical methods. Thus, a general chemical analysis will also include aluminum which is present in the form of cations which are associated with the acidic positions in the zeolite, whereby a low silicon dioxide : aluminum oxide ratio is obtained. If in a similar way the ratio is determined by a thermogravimetric analysis (TGA)

by means of ammonia desorption, a low ammonia titration will be achieved if the cationic aluminum prevents a yield of the ammonium ions on the acidic positions. These irregularities create particular problems when using certain treatments, e.g. the dealumination method described below, which results in the presence of ionic aluminum free from the zeolite structure. You must therefore ensure that you correctly determine the silicon dioxide:alumina ratio in the structural lattice itself.

The silicon dioxide : aluminum oxide ratio in the zeolite can be determined by the type of starting material used in the production of the zeolite and their relative amounts. A certain variation in the ratio can be achieved by changing the relative concentration of the silica precursor compound in relation to the alumina precursor, but there are certain limits to what can be achieved for the maximum silica:alumina ratio in the zeolite.

For zeolite beta, this limit is usually approx. 100 :: 1

(although higher ratios can also be achieved), and for ratios beyond this value, other methods are usually required for the production of a desired zeolite with

high silicon dioxide content. Such a method includes dealumination by carrying out an extraction with acid, and this method includes contacting the zeolite with an acid, preferably a mineral acid, such as hydrochloric acid. The dealumination process takes place at room temperature or at slightly elevated temperatures, and usually occurs with minimal loss of crystallinity. This method can be used to produce high-silicon dioxide-containing forms of zeolite beta with a silicon dioxide:alumina ratio of at least 100:1, and ratios of 200:1 or even higher can easily be achieved.

The zeolite can conveniently be used in the hydrogen form for the dealumination process, although other cationic forms can also be used, e.g. the sodium form. If these other forms are used, sufficient acid must be used so that the original cations in the zeolite are replaced by protons. The amount of zeolite in the zeolite/acid mixture should usually be from 5 - 60% by weight.

As mentioned above, the acid can be mineral acid, e.g. an inorganic acid or an organic acid. Typical inorganic acids that can be used include mineral acids such as hydrochloric, sulfuric, nitric and phosphoric acids, peroxydisulfonic acid, dithionic acid, sulfamic acid, peroxymonosulfuric acid, amidodisulfonic acid, nitrosulfonic acid, chlorosulphuric acid, pyrosulphuric acid and nitrous acid. Representative organic acids that can be used are e.g. formic acid, trichloroacetic acid and trifluoroacetic acid.

The concentration of the added acid should be such that the pH of the reaction mixture is not lowered to an undesirably low level, which could affect the crystallinity of the zeolite being treated. The degree of acidity which the zeolite can tolerate will at least depend on the silicon dioxide/alumina ratio in the starting material. In general, it has been found that zeolite beta can withstand concentrated acids without excessive loss of crystallinity, but as a general rule an acid should be used that is in strength in the range from 0.1 normal to 4.0 normal, usually from 1 to 2 normal. These values are applicable regardless of the silica:alumina ratio in the starting material. Stronger acids give a stronger degree of aluminum removal than weaker acids.

Said dealumination reaction takes place easily at room temperature, but slightly elevated temperatures can also be used, e.g. up to 100°C. The duration of the extraction will depend on the silica:alumina ratio of the product, as the diffusion-controlled extraction is time-dependent. However, as the zeolite becomes progressively more resistant to loss of crystallinity as the silica:alumina ratio increases, it consequently becomes more stable as the aluminum is removed, allowing higher temperatures and more concentrated acids to be used at the end of the treatment than at the beginning without that one risks loss of crystallinity.

After extraction, the product is water-washed free of impurities, preferably in distilled water, until the wash water has a pH

in the range from 5 to 8.

The crystallinity of dealuminated products produced by the present method has essentially the same crystallographic structure as in the starting material, but with an increased silicon dioxide:alumina ratio. The formula of the dealuminated zeolite beta will therefore be:

where X is less than 1, preferably less than 0.75, Y is at least 100, preferably at least 150 and W is up to 60. M is a metal, preferably a transition metal or a metal from groups IA, 2A or 3A of the periodic table , or a mixture of metals. Silicon dioxide : aluminum oxide

the ratio Y will usually lie in the range from 100:1 to 500:1, more commonly from 150:1 to 300:1, e.g. 200:1 or more. The X-ray diffraction pattern for the dealuminated zeolite will essentially be the same as for the free-flowing zeolite, i.e. as indicated in table 1 above.

If desired, the zeolite can be steam-treated before the acid extraction in order to thereby increase the silicon dioxide:alumina ratio and make the zeolite more stable to the acid. The steam treatment will also make it easier to remove the acid and promote the retention of crystallinity during the extraction,

Zeolite beta is preferably used in combination with a hydrogenation component which is usually derived from a metal from groups VA, VIA, or VIIIA of the periodic table. Preferred non-noble metals are such as tungsten, vanadium, molybdenum, nickel, cobalt, chromium and manganese, and the preferred noble metals are platinum, palladium, iridium and rhodium. Combinations of non-noble metals such as cobalt-molybdenum, cobalt-nickel, nickel-tungsten or cobalt-nickel-tungsten are exceptionally usable with many starting compounds, and in a preferred combination the hydrogenation component is from 0.7 to 7% by weight nickel and from 2.1 to approx. 21 wt% tungsten expressed as metal. The hydrogenation component can be exchanged on the zeolite, impregnated on it or physically attached to it. If the metal is to be impregnated in or replaced on the zeolite, then this can e.g. is done by treating the zeolite with a platinum metal-containing ion. Suitable platinum compounds include chloroplatinic acid, platinum chloride and various compounds containing platinum amine complexes, e.g.

The catalyst can be treated by commonly known presulphidation treatments, e.g. by heating in the presence of hydrogen sulphide to convert the oxide forms of the metals such as CoO

or NiO to their corresponding sulfides.

The metal compounds can either be compounds where the metal is present in the cation of the compound, or compounds where the metal is present in the anion of the compound. Both types of connections can be used. Platinum compounds where the metal is in the form of a cation or cationic complex, e.g. Pt(NH^)4-CI2, are particularly useful, and the same applies to anionic complexes such as the vanadate and the metatungsten ions. You can also use cationic forms of other metals since these can be replaced on the zeolite or impregnated on it.

Before use, the zeolite should be at least partially dehydrated. This can be done by heating to a temperature in the range from 200 to 600°C in air or in an inert atmosphere such as nitrogen, for a period of from 1 to 48 hours. Dehydration can also be carried out at lower temperatures by using a vacuum, but a longer period of time is then required to achieve a sufficient degree of dehydration.

It may be desirable to incorporate the catalyst in another material that is resistant to the temperature or the other conditions used in the process. Such matrix materials include synthetic and naturally occurring substances, such as inorganic compounds, e.g. clay, silicon dioxide and metal oxides. The latter can either be in its naturally occurring form or in the form of gelatinous precipitates or gels which include mixtures of silicon dioxide and metal oxides. Naturally occurring clays may be mixed with the zeolite, and include those of the montmorillonite and kaolin types. The clays can be used in the raw state as they are taken out or subjected to a calcination, an acid treatment or chemical modification.

The zeolite can be composed of a porous matrix material, such as alumina, silica-alumina, silica-magnesium oxide, silicon dioxide-zirconia, silicon dioxide-thorium oxide, silicon dioxide-beryllium oxide, silicon dioxide-titanium oxide, as well as ternary compositions such as silica-alumina-thorium oxide, silicon dioxide-alumina-zirconia , magnesium oxide and silicon dioxide-magnesium oxide-zirconia. The matrix can be in the form of a sand gel. The relative proportions of the zeolite component and the inorganic oxide gel matrix on an anhydrous basis can vary greatly, and the zeolite content can vary from 10 to 99, usually from 25 to 80% by weight based on the dry weight. The matrix itself can have catalytic properties, usually of an acidic nature.

Feedstock for the present process includes a heavy hydrocarbon oil such as a gas oil, coke tower bottoms, reduced crude oils, vacuum tower bottoms, deasphalted vacuum residues, FCC tower bottoms and cyclic oils. Oil derived from coal, shale or tar sands can also be treated in this way. Oils of this type usually boil above 34 3°C, but the method can also be used with oil that has initial boiling points as low as 260°C. These heavy oils include high molecular weight long chain paraffins and high molecular weight aromatic compounds with a large amount of compound ring aromatic compounds. During the processing, the compound aromatic compounds and naphthenes will be cracked by the acid catalyst and the paraffinic cracked products together with the paraffinic components of the original starting material will be subjected to a conversion to iso-pajuafines with some cracking to low molecular weight compounds. Hydrogenation of the unsaturated side chains in the monocyclic cracking compounds from the original polycyclic compounds is catalyzed by the hydrogenation component to substituted monocyclic aromatic compounds which are highly desirable end products. The heavy hydrocarbon oil used as starting material will normally contain a significant amount of compounds boiling above 2 30°C, and will normally have an initial boiling point of approx. 290°C, more common approx. 340°C. Typical cooking areas will be from approx. 340

to 565°C or from approx. 340 to 510°C, while you can of course also process oils with a narrower boiling range, e.g. those with a boiling range from 340 to 455°C. Heavy gas oils are often

of this type, and the same applies to so-called cyclic oils or other non-residual compounds. It is also possible at the same time to process compounds that boil below 2 60°C, but the degree of conversion for such components will be lower. The starting material containing lighter compounds of this type will normally have an initial boiling point of over 150°C.

The present method is particularly applicable with starting materials that have a high content of paraffinic compounds, with starting materials of this type achieving the greatest improvement in terms of solidification point. However, most starting materials will contain some amount of polycyclic aromatic compounds.

The present procedure is carried out under conditions

which correspond to those used for conventional hydrocracking, although the use of a zeolite catalyst with a high silicon content makes it possible to reduce the total pressure requirements. You can appropriately use process temperatures from 230 to 500°C, although you normally do not want to use temperatures above 425°C as the thermo-dynamics of the hydrocracking reaction then become unfavorable at higher temperatures. Generally, temperatures from 300 to 425°C will be used. The total pressure will usually lie in the range from 500 to 20,000 kPa, and pressure in this range of over 7,000 kPa will normally be preferred. The process is operated in the presence of hydrogen and the hydrogen's partial pressure will normally lie in the range from 600 to 6000 kPa. The ratio of hydrogen to the hydrocarbon starting material (hydrogen circulation quantity)

will normally be from 10 to 3500 n.l.l""'". The space velocity for the starting material will normally be from 0.1 to 20 LHSV, preferably 0.1 to 10 LHSV. At low conversions, the n-paraffins in the starting material will preferably be converted to isoparaffins, but at higher conversions under stronger conditions the isoparaffins will also be converted.The product will have a low content of fractions boiling below 150°C,

and in most cases the product will have a boiling range from 150 to 340°C.

The conversion can be carried out by contacting the starting material

a fixed stationary bed of catalyst, a fixed fluidized bed or with a moving bed. A simple process is a so-called sieve bed operation where the starting material is sieved through a stationary fixed bed. With such a configuration, it is possible to start the reaction with fresh catalyst at a moderate temperature and this is raised as the catalyst ages to maintain catalytic activity. The catalyst can be regenerated by contacting it with hydrogen gas at an elevated temperature, for example, or by burning it in air or another oxygen-containing gas.

A preliminary hydrotreating step to remove nitrogen and sulfur and to saturate the aromatic compounds to naphthenes without significant conversion of the boiling range will usually improve the properties of the catalyst and enable the use of lower temperatures, higher space velocities, lower pressures or combinations of these conditions.

The method according to the present invention is illustrated by means of the following examples. All parts and. quantity ratios in these examples per weight unless otherwise stated.

Example 1

This example illustrates the preparation of a catalyst.

A mixture of zeolite beta (SiO 2 /Al 2 O 2 =30) with a crystallite size of less than 0.05 micron and an equal amount of gamma alumina on an anhydrous basis was extruded into pellets with a diameter of 1.5 mm. Said pellets were calcined at 540°C in nitrogen, they were magnesium recovered and then calcined in air.

One hundred grams of said air-calcined product was impregnated with 13.4 g of ammonium metatungstate (72.3% by weight) in 60 ml of water, followed by drying at 115°C and calcination in air at 540°C. The product was then impregnated with 15.1 g of nickel nitrate hexahydrate in 60 ml of water, and the wet pellets were dried and calcined at 540°C.

The final catalyst had a nickel content of approx. 4% by weight as NiO and a calculated tungsten content of approx. 10.0% by weight as WO 2 . The sodium content was less than 0.5% by weight as sodium oxide.

Example 2

This example describes the preparation of zeolite beta with a high content of silicon dioxide.

A sample of zeolite beta in its synthetically cited form and with a silica:alumina ratio of 30:1 was calcined in flowing nitrogen at 500°C for 4 hours followed by air at the same temperature for 5 hours. The calcined zeolite was then refluxed with 2N hydrochloric acid at 95°C for one hour, whereby a dealuminated zeolite beta with a high content of silicon dioxide and with a silicon dioxide : aluminum ratio of 280 : 1, an alpha value of 20 and a crystallinity of 80% compared to the original product, which was assumed to be 100% crystalline.

The zeolite was exchanged into the ammonium form with a 1N ammonium chloride solution at 90°C and then refluxed for one hour followed by exchange with a 1N magnesium chloride solution at 90°, the product being refluxed for one hour. Platinum was introduced into the zeolite by ion exchange using the tetramine complex at room temperature. The metal-exchanged zeolite was washed and oven-dried by air calcination at 350°C for 2 hours. The finished catalyst contained 0.6% platinum and was pelleted, crushed and sieved to 0.35 to 0.5 mm.

Examples 3-5

The catalyst from Example 1 was evaluated for catalytic convertibility on an Arabian light gas oil (HVGO) having a boiling range of 354 to 580°C. For comparison, a magnesium-yielded zeolite Y (SiC^/A^O^S) catalyst was also prepared by expelling an equal amount of gamma aluminum oxide and impregnating this until it contained 4% by weight of nickel and 10% by weight of tungsten.

The composition of the starting material, the conditions used and product analysis are given in table 2 below.

As shown above in table 2, the beta catalyst gives a relatively high conversionQ of almost 60%, a significant lowering of the solidification point of the 343 C+ product, while the products obtained with the help of the zeolite Y catalyst remained waxy. Furthermore, the beta catalyst converted significantly more of the high-boiling components in the starting material, which resulted in a 343°C+ product with an end point approx. 55°C lower than what was obtained with the catalyst from example 4. The hydrogen consumption was also significantly lower, whether this was calculated on an absolute basis or in relation to the conversion.

For a comparison with Example 3, a similar light Arabian HVGO with a boiling range from 370° to 550°C was hydrocracked over a rare earth metal yielded ultrastable zeolite Y (SiG^xA^O^ =75). The zeolite was prepared by steam calcination and acid dealuminization of zeolite Y to a structural ratio of SiO-^A^O^ of 75 : 1, followed by an exchange with rare earth metals, expulsion with a corresponding amount of gamma alumina and impregnation so that the catalyst contained 2 wt% nickel and 7 wt% -% tungsten.

The composition of the starting material, the conditions used and product analysis are given in table 3.

Claims (10)

1. Method for cracking and dewaxing a heavy hydrocarbon oil, characterized by contacting the oil with a catalyst consisting of zeolite beta. 2. Method according to claim 1, characterized in that the oil is contacted in the presence of hydrogen with a catalyst consisting of (i) zeolite beta as an acidic component and (ii) a hydrogenation component. 3. Method according to claim 2, characterized in that said zeolite beta has a silicon dioxide: alumina ratio greater than 50:1. 4. Method according to claim 2 or 3, characterized in that the hydrogenation component includes nickel, tungsten, cobalt, molybdenum or a mixture of each of two or more such metals. 5. Method according to claim 4, characterized in that the hydrogenation component includes nickel and tungsten. 6. Method according to claim 2 or 3, characterized in that the hydrogenation component includes platinum, palladium, iridium, rhodium or a combination of two or more such metals. 7. Method according to each of claims 1-6, characterized in that the oil has an initial boiling point of over 290°C. 8. Method according to claim 7, characterized in that the oil has an initial boiling point of over 340°C. 9. Method according to claim 8, characterized in that the oil has a boiling point between 340 and 565°C. 10. Method according to each of claims 2-9, characterized in that the oil is contacted with the catalyst in the presence of hydrogen gas at temperatures between 230 and 500°C, a pressure of from 500 to 20,000 kPa, a space velocity of from 0.1 to 20 and a hydrogen circulation rate of from 10 to 3500 n.1.1." <1> .