CS276113B6 - Process for preparing medium-boiling hydrocarbon distillation product - Google Patents

Abstract

In a hydrocracking process for prodn. of middle distillates of b.pt. 149-371 deg.C using a catalyst compsn. comprising a refractory inorganic oxide matrix and a H-form zeolite having the characteristic X-ray powder diffraction pattern of zeolite Y, the zeolite having a unit cell size of 24.20-24.40 Angstroms, the improvement is that the zeolite is a low acidity zeolite having an ion exchange capacity above 0.07 and a bound OH content sufficiently low to provide an ammonia temp. programmed desorption (NH3-TPD) acidity strength value of less than 2.00, pref. less than 1.50.

Description

The present invention relates to a process for hydrocracking a hydrocarbon feed stream to produce a medium-boiling hydrocarbon distillate, the so-called middle distillate, boiling in the range of 149-371 ° C using a modified low-acid z-cecite Y catalyst.

Hydrocracking is a process used in petroleum refining, in which 3Q molecules of a hydrocarbon substance partially decompose in the presence of hydrogen to obtain a more needed lower molecular weight product. Due to the increased demand for mid-boiling distillates, such as jet fuel and diesel fuel / there is a growing interest in hydrocracking. Namely, hydrocracking degrades smaller gas and coke feedstocks as compared to thermal cracking or hydrogen-free cracking, and therefore produces a larger liquid product stream with a boiling range corresponding to a medium-boiling distillate.

Deciding! the hydrocracking element consists in the use of a special catalyst which is highly active in both cracking and hydrogenation. It is known from the prior art that a large number of these dual function catalysts, the cracking efficiency, measured by the conversion of feed to product, is most often attributed to the solid acid components present in the catalyst base. Hydrogenation efficiency, on the other hand, is attributed to various metals deposited on the catalyst base. These metals are usually selected for Groups VIB and VIII of the Periodic Table of the Elements.

Popular catalysts used in the middle distillate industry include metal (s) and / or metal compounds selected from Group VIB or VIII of the Periodic Table deposited on an amorphous refractory inorganic oxide base such as a mixture of silica and alumina and alumina. Recently, a major effort has been directed in industrial research to develop hydrocracking catalysts containing crystalline aluminosilicates as the basis.

Zeolite-type aluminosilicates usually have a higher total acidity than amorphous oxides and therefore exhibit a higher cracking activity. Due to this property, zeolites are considered to have excellent catalytic effect on hydrocarbon conversion. In research into the development of zeolite hydrocracking catalysts, special attention is paid to the type Y yolite, which was originally disclosed in U.S. Patent No. 3,130,007. The mechanism of catalyzing Y-type ooliths is not fully understood. However, it has been found that the hydrocracking catalyst containing zeolite Y exhibits not only increased activity in the formation of a medium-boiling distillate, but also improved selectivity in favor of the desired medium-boiling distillation product.

The zeolite-based hydrocracking catalysts described in the prior art include zeolite Y or various modifications of zoolite Y in a refractory inorganic oxide matrix. For example, zeolite Y can be modified by increasing the molar ratio of silica to alumina and reducing the free cell element.

U.S. Patent No. 4,419,271 (Ward Ward IV) discloses a hydrocarbon conversion catalyst suitable for hydrocracking comprising a core of nobo-hydrogenation components deposited on a base comprising a crystalline aluminosilicate zeolite having hydrocarbon cracking activity and a silica-alumina dispersion in aluminium matrix. The patent teaches that in order to produce a zolite with the desired cracking actuality, it is necessary to replace alkali metals, metal cations of polyvalent metals, hydrogen ions or precursors of hydrogen ions, which is usually done by ion exchange. A substance with good cracking activity is obtained by reducing the alkali metal content to less than 5% by weight and preferably less than 0.5% by weight (based on the alkali metal oxides). Most preferably, zeolite, for use as a hydrocracking catalyst component, discloses zeolite Y having an alumina / alumina ratio of about 3.5 days G, C, a specific surface area of about 500 to 700 m / g, elemental cell selectivity approximately within range! 2,425 to 2,435 nm, an adsorption capacity for water of less than about 3 fo by weight based on the zeolite (at parCS 27S 113 B6 of

water vapor pressure of 613.2 Pa and 25 ° C) and an ion exchange capacity of less than 20% of the ion exchange capacity of zeolite Y in sodium form 3β with a comparable silica / alumina ratio.

U.S. Pat. No. 4,401,556 (R. 0. Bezman et al., Rabo) discloses a hydrocarbon conversion catalyst comprising ultrahydrophobic zeolite Y (UHP-Y), which is characterized by having a 3-molar / alumina molar ratio in the range from 4.5 to 35, powder X-ray diffraction pattern substantially corresponding to zeolite Y, ion exchange capacity less than 0.070, elemental cell dimensions from 2.420 to 2.445 nm, specific surface area of at least 350 m / g (BET), water vapor sorption capacity at 25 ° C and a p / p ° 0.10 of less than 5.00% by weight and a residual butane test value of less than 0.40% by weight.

U.S. Patent No. 4,517,073 (O. W. Ward) discloses a hydrocracking catalyst comprising a c16 active hydrogenation component on a support comprising a silica-alumina dispersion in alumina type Y and a silica / alumina molar ratio above about 6.0. The zeolites used in the hydrocracking catalysts described in this patent have a substantially crystalline Y zeolite structure, containing alkali metals in an amount of less than 1.5% by weight (calculated as total monovalent metal oxide content), and having a unit cell size of generally 2.455 nm or less . The preferred silica / alumina molar ratio is from about 6 to about 20, and if the molar ratio is below 20, the zeolites have a water vapor adsorption capacity at 25 ° C and a water vapor partial pressure of at least 20% by weight according to the zeolite patent, based on the anhydrous weight of the zeolite, and preferably an oxygen adsorption capacity at 13.33 kPa and 183 ° of at least 25% by weight.

The above patents are disclosed to illustrate prior art Y-type zeolite hydrotracing catalysts. The type Y zeolites described in the prior art for use in hydrocracking are characterized by properties such as silica / alumina molar ratio, elemental cell size, ion exchange capacity, specific surface area and water sorption capacity. Bifunctional catalysts, i.e., dual-function catalysts used in hydrocracking, exhibit cracking and hydrogenation activity, and it is well known in the art that the acidity of the catalyst component affects the cracking activity of the catalyst. The question of the acidity of zeolites and its influence is, for example, discussed in Duvyer and Mewoam, hereinafter. However, although researchers in the hydrocracking industry have made a tremendous effort in this regard, they have not paid attention to the effect of the hydroxyl concentration, which has a direct relationship to the acidity of the cracking component (such as zeolite Y) on selectivity.

The reference to dehydroxylation is generally scarce in the literature. None of the exceptions is a series of references including US Patent No. 4,790,920 to C. Chang and others. This reference refers to the performance improvement of ZSM-5 zeolite and other medium pore zeolites by selective dehydroxylation. When the resulting zeolite is incorporated into the catalyst, it is said to be useful for catalytic dewaxing of petroleum fractions, such as atmospheric oil distillation residue or vacuum gas oil. The dehydroxylation is performed by calcining at a temperature above 50 C in nepřitomnossi ^Q water.

A discussion of studies on the hydroxy content of Y-type zeolites and the effects of calcination is given on pages 140-147 of the American Chemical Society Monograph 171, eds. A. Rabo.

The use of low acid catalysts for hydrocracking is discussed in U.S. Patent No. 4,263,129 (N.Y. Clien et al.). However, this reference is limited to the use of zeolites such as ZSM-5 with a eilica / alumina ratio above 12. Low acidity is preferably achieved by extensive ion exchange in the zeolite using sodium or other alkali metal, which leads to a high sodium content, albeit also mentioned steam treatment to reduce acidity. The invention differs from this reference in that it uses low Y sodium type zeolites and a low 3-alumina / alumina ratio.

U.S. Patent No. 3,929,672 (O. W. Ward) compares the effect of calcination in the presence of water vapor and dry on Y zeolites. It is reported that dry calcination results in loss

CS 2713 113 136 crystallinity '

SUMMARY OF THE INVENTION The present invention provides a process for hydrocracking a hydrocarbon feed stream comprising at least 50 volume components boiling above 371 ° C to produce a boiling hydrocarbon distillate having a boiling point of nd 147 to 371 ° C wherein the feed stream is contacted with a catalyst comprising a hydrogenation component from the group consisting of molybdenum, tungsten, nickel, cobalt, platinum, palladium and iron, an inorganic matrix containing 45 to 90% by weight of allium alumina and 5 to 45% by weight of alumina and Y-type zeolite in hydrogen form having an elemental cell size of 2.440 nm, under hydrocracking conditions including a temperature of 204 to 049 ° C, an overpressure of 1373 to 20 065 kPa, a liquid fusion space velocity of 0.1 to 15 h ^{3- 3} and a hydrogen circulation rate of 355 to 5 333 Nm .h; The method of claim 1, wherein the catalyst has a zeolite component having an ion exchange capacity of greater than 0.07 and an acid value of NHg-TPO of less than 1.50.

It follows the detailed description of the invention. Oak As noted above, the present invention relates to an improved hydrocracking process for producing a medium boiling hydrocarbon distillate and a catalyst suitable for the process, which exhibits increased activity and increased selectivity for medium boiling distillate.

The invention is based on the finding that salt Y-type in hydrogen form on the surface of which hydroxyl groups are bound in low concentration is an excellent hydrocracking catalyst. This catalyst, which can be characterized by temperature-programmed ammonia absorption (NH.J-TPO), exhibits increased selectivity in the production of a medium-boiling hydrocarbon distillate by hydrocracking.

The hydrocracking catalyst of the invention comprises a crystalline zeolite of the type

Y. Y-type zeolite is generally described in U.S. Patent No. 3,130,007.

The chemical structure of the oolite Y expressed in the molar ratio of oxides can be characterized by the formula

W, θ + ρ ^ Νο-, ΟίΑΐ-, Ο ^ η'Λΐ.ΙΟ, ίχΙ ^ Ο, where w represents a number from 3 to about 6 and x represents Number e by up to about 3.

The classical structure of zeolite Y is formed by a three-dimensional lattice of SiO4 and AlO4 tetrahedrons intertwined by oxygen atom sharing. The electrical charge of aluminum-containing tetrahedra is counterbalanced by the presence of cations such as metal ions, for example rare earth metal ions, alkali metal ions, ammonium ions, amine complexes, and hydrogen ions. Empty spaces in the grid can be filled with water molecules. Under normal conditions, the crystalline zeolite occurs or is formulated with an alkali metal. The classification of the substance as zeolite Y is essentially based on the finding that the substance exhibits the above formula and has a well-known X-ray x-ray pattern. The oolites Y may contain in their structure germanium, gallium, phosphorus or boron, and fen along with or instead of traditional eilica and alumina.

The acidity of zeolite has been the subject of extensive research and conjecture. For example, the effect of acidity on catalytic activity and the relationship between the composition and acidity of zeolites is discussed in Article 3 of Dwysra on page 256 of Chemistry and Industry, April 2, 1984. The article states that evidence shows that active Bronstad sites are formed hydroxyls in the zeolite channels. Two types of hydroxyls are described herein: surface and terminal hydroxyls and bridged hydroxyls in larger pores. A wide discussion of and concerns the acidity, composition, activity and selectivity of the catalyst. It is reported that the selectivity of the product is determined

The geometry and pore size and their effect of reducing diffusion to selective sites within the structure, rather than acidity.

In Article □. M. Newsama in Science Magazine of March 7, 1986 (Vol. 231, p. 1093) states that most of the reactions involved in catalytic cracking involve the acidic site located in the zeolite, which is mainly attributed to bridged hydroxyl groups. Acidic sites 33 assume on protonated tetraethral aluminum in a silica-rich zeolite lattice.

As illustrated by the data below, it has been found that the selectivity of the zeolite in the hydrogen form for the formation of products corresponding to the medium-boiling hydrocarbon distillate is directly correlated with the acidity of the zeolite, which in turn is determined by the hydroxyl group concentration on the zeolite. Oak catalysts based on such zeolites and low in hydroxy groups, as well as their use in hydrocracking, are considered novel.

Since it is currently not possible to directly measure the hydroxyl group concentration, these measurements must be carried out indirectly. The analytical method chosen consists of measuring the acidity of the zeolite. It is believed that acidity is correlated with the concentration of hydroxy groups.

Temperature programmed ammonia desorption (tMjPPD) is a widely used and effective method for determining the acidity of zeolites (see Hidalgo CV et al., Maaourement of Acidity of Various Zeolites by Temperature-Prcgrammed Desorption of Ammonia, Vol. 05, No. 2). pp. 362-369 (1984) Ammonia is an excellent test molecule for the TPD process, which is small in size, which allows them to penetrate very well into the pores and is strongly alkaline, so that they immediately settle in acidic sites. because it is relatively simple, consumes minimal time and can be accurately reproduced.

The MHg-TPD procedure used is carried out by sampling a zeolite having a mass of 0.250. +

0.001 g was first heated in air at 500 ° C and flow rate 60 ml / min for 75 minutes and then in helium at 500 ° C and flow rate 60 ml / min for 15 minutes. The pre-treated zeolite was then cooled to room temperature over about 20 minutes under a helium atmosphere. To achieve equilibrium, the zeolite sample is saturated 5 times with a 10 ml aliquot (under atmospheric conditions) of ammonia gas. The saturated zeolite was then purged with helium at room temperature and a flow rate of 60 ml / min for 35 minutes. Immediately thereafter, the gas stream is introduced into the gas chromatograph, the sample being heated in a programmed manner at a rate of 8.33 ° C / min to a maximum of 650 ° C. The ammonia desorption is monitored on the recorder over a temperature range of 25 to 500 ° C over 75 minutes.

The area under the desorption curve recorded by the gas chromatograph is correlated with the total amount of ammonia absorbed. Analysis of the outgoing gases by mass spectrometry shows that there is negligible deeorption of impurities at a temperature ranging from 25 to 500 ° C. The desorption curve is calibrated by trapping desorbed ammonia in 10% sulfuric acid and quantitating it in a manner known in the art. It is found that the amount of ammonia desorbed per unit area under the desorption curve is 0.038 µh 0.004 mmol / unit area.

The acidity value of NHg-TPO with 3-tane integration of the desorption curve in the interval from 25 to 500 ° C. The area under the curve is then multiplied by a factor of 0.030 mmol / unit area and divided by the sample weight (0.250 g). This gives the acid value NHg-TPD in mmol / g. For example, if an integration of 25 to 500 ° C is found by integrating a celite surface corresponding to 10 units, the acid value of MH @ + -TPD is calculated as follows: 10 units of area x 0.030 mmol NH4 / unit of area / 0.250 g sample = 1.52 mmol) g of sample.

All acid values of NHg-TPD reported in the description of this invention are expressed in mmol / g of sample, although for simplicity these units are sometimes omitted. When reproducing the acid values of NH 4 -TPD, it is necessary to precisely observe the key experimental conditions such as the rate of temperature increase, sample size, flow rate and equilibrium temperature. Comparing acidity values obtained by different techniques is often difficult. In any case, however, it is to be understood that the acid values contemplated by the invention do not include only the s values

CS 276 113 SG determined by the NH ₃ -TPD test described above, but also equivalent values that would be measured on the same sample using alternative techniques.

The Y-type zoolites suitable for use in the process of the invention exhibit a silica to alumina ratio (in the grid) of less than 6.0.

The Y-type zeolite useful in the present invention should have a unit cell size in the range of 2.420 to 2.445 nm. Preferred unit cell sizes are in the range of 2.420 to 2.440 nm and most preferably are about 2.130 nm. In the prior art, 3Θ has claimed that hydrocracking catalysts containing zeolite may be sensitive to modification of the size of the elemental cell of zeolite. however, the acidity value is apparently independent of this parameter. The decrease in acidity and reduced cell size is due to a decrease in the aluminum content of the zeolite, and this phenomenon is not related to the different acidity values of zeolites having 3 and the same silica to aluminum ratio and / or the same elemental cell dimensions.

The type Y zeolites contemplated by the invention should have an acid value of NHg-TPD of less than about 2.00. Preferred acid values are less than about 1.50 and most preferably are in the range of from 0.1 to 0.70.

The type of particular process by which zeolite Y in hydrogen form and reduced acidity occurs is not considered to be of critical importance according to the invention. Thus, a suitable hydrocracking catalyst can be prepared from any of the starting materials which, to the X-ray powder diffraction pattern substantially corresponding to zeolite Y as described in U.S. Patent No. 3,130,007. The starting material can be modified by any acid reduction technique known in the art. results in the desired hydrogen form of the zeolite. Thus, modification approaches such as hydrotharmal treatment at elevated temperatures, calcination, impregnation or reaction with acid depressants, crystallization, and any combination of these methods can be used.

Neither the specific methods of modifying the zeolites nor the particular processes for their preparation are important to the invention. Any hydrogen form of zeolite Y having a suitably low concentration of hydroxyl groups can be used in the hydrocracking catalyst of the invention.

One of the methods of reducing acidity is a hydrotharmal treatment carried out at a temperature above 500 ° C for at least 0.5 hours. A preferred method of reducing acidity is dry air calcination at a temperature above 500 ° C for at least 0.5 hours. A preferred acid sedimentation saloon consists in dehydroxylating the zeolite at a temperature above at least 704 ° C for at least one hour, the operation being carried out essentially in the absence of water. It is believed that the choice of a particular modification process is not critical to the invention. Two or more different modification techniques may also be used.

The hydrocracking catalyst according to the invention should contain 2 to 20% by weight, preferably 2 to 10% by weight of Y-type zeolite. The catalyst according to the invention also comprises a porous refractory inorganic oxide matrix which may comprise 2 to 38% and preferably 5 to 95% by weight. the resulting catalyst support. The matrix may comprise any known refractory inorganic oxide, such as alumina, magnesium, silica, titanium dioxide, zirconia, silica-alumina, etc., and combinations thereof.

The foresheet matrices are of silica-alumina or alumina. Most preferably, the matrix consists of a mixture of silica-alumina and alumina in which the silica-alumina forms between 45 and 90% by weight. It is also preferred that the carrier comprises from about 5 to about 45% by weight of alumina.

The silico-alumina component can be produced by any of a number of techniques that are relatively well described in the related art of the prior art toch. These techniques include acid treatment of natural clays or sands, coprecipitation or sequential precipitation from hydrosols. These techniques are often combined with one or more activation procedures such as hot oil aging, steaming, drying, oxidation, reduction, calcination, etc.

CS 27S 113 06

The carrier pair structure, which is generally defined by specific surface area, pore diameter, and pore volume values, can be developed to meet the above limits by any suitable method, such as aging the hydrosol and / nsbo hydrogel under controlled acidic or alkaline conditions at room temperature. or at elevated temperature or gelatinization of the carrier at a critical pH or by treating the carrier with various inorganic or organic reagents.

The resulting catalyst useful in the hydrocracking process should have a specific peak of from about 200 to 700 m / g, a pore diameter of from about 2 to about 30 nm, a pore volume of from about 0.10 to about 0.00 ml / g, free flowing. a weight ranging from about 0.50 to about 0.90 g / cm 2. A specific surface area above 350 m / g is highly preferred. ,

The alumina component of the catalyst may be any of a variety of hydrated alumina or alumina gels such as Boehmite-alpha-alumina monohydrate, Gibbite-alpha-alumina trihydrate, beta-alumina-trihydrate and bayerite, and the like. the so-called Ziegler alumina, which is described in U.S. Pat. Nos. 3,852,190 and 4,012,313, as a byproduct formed. in the Ziegler synthesis of higher alcohols described in Ziegler U.S. Patent No. 2,922,850. A preferred type of alumina is currently available from the Conoco Chemical Division of the Continental Oil Company under the trade name Catapal. This substance consists of a highly pure alpha-alumina monohydrate with a boehmite structure which, after high-temperature calcination, yields a highly pure gamma-olumine.

The precise specific characteristics of the carrier, such as shape and specific surface, do not limit the scope of the invention. For example, the catalyst may be in the form of pills, pellets, granules, debris, spheres, or various special shapes such as trilobial extrudates arranged in the reaction zone as a fixed bed. Alternatively, the catalyst may be made in a form suitable for use in moving bed reaction zones in which the hydrocarbon feed and catalyst are conducted either countercurrent or co-current or in fluidized bed reaction zones in which the feed is directed upward through the turbulent bed of the finely divided catalyst; in a form suitable for use in slurry processes in which the catalyst is suspended in the feed and the resulting mixture is discharged into the reaction zone. Handle. it may include a reactor or reactors either in the liquid, vapor nobo mixed phase, wherein the flow direction may be either from the bottom up or from the top down.

The catalyst particles can be produced by any known method in the art, such as by well known oil dropping and extrusion methods. In oil drip production, catalyst particles can be prepared as follows: the selected powdered zeolite is suspended in a suitable sol. Active metal components can also be added to the sol. The salt mixture is then added dropwise to an oil bath which is maintained at elevated temperature and the drops are left in the oil bath until they form gel spheres. The spherical particles are then removed from the oil bath and aged for an appropriate period of time in a suitable suspension medium at elevated temperature. Then the spherical particles are dried and calcined. When the matrix is to be of alumina or silica-alumina, the ee can be dripped into the oil process as described in US Patent No. 2 G20 314 or 3 003 972.

A preferred method of preparing the catalyst of the present invention is by co-grinding the selected zeolite with both alumina and amorphous 3-alumina. Prior to 3 minutes, the added ingredients are preferably comminuted to a striped form. At this time, active metal components can also be added to the mixture. After grinding, the mixture is extruded through a die containing suitable apertures, for example a circular or quadrilateral, to form an extrudate of the desired shape. The extrudate may be chopped to a length of 12.7 to 6.3 mm and then dried and calcined at elevated temperature under conditions well known in the art.

While the hydrogenation active ingredients may be added to the nobo oil prior to extrusion prior to catalyst production, they are preferably introduced into the catalyst by impregnation only after the formation of the zeolite and the refractory inorganic oxide, drying and calcination. Filling ko7

CS 273 17.3 The BG hydrogenation component into the particles may be carried out by any method known in the art, such as using evaporation, soaking and vacuum impregnation. In general, the dried and calcined particles are contacted with one or more solutions containing the desired hydrogenation active ingredients in dissolved form. After a suitable contact time, the composite particles are dried and calcined to form the resulting catalyst particles. Further data relating to the production of suitable catalysts in a suitable form can be found in numerous references, such as in US patents 4,588,495 and 4,500,498. These references relate to the preparation and use of hydrogenation catalysts containing Y zeolites.

Suitable hydrogenation components are catalytically active components selected from the group consisting of clusters VIO and VIII of the periodic table and their compounds. The amount of hydrogenation components present in the resulting catalyst is usually small compared to the amount of the other components mentioned above mixed with them. The Group VIII component is generally about 0.1 to about 30%, preferably about 1 to about 15% by weight of the resultant catalyst composite based on the elements. The Group VIB component constitutes about 0.05 to about 30%, and preferably about 0.5 to about 15% by weight of the resultant catalyst composite, based on the elements. The hydrogenation components include one or more metals selected from the group consisting of molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, palladium, iridium, osmium, rhodium, ruthenium, and mixtures thereof.

The hydrogenation components are most likely to be present in oxidic form after calcination in air, and can optionally be converted to the sulfide form by bringing them into contact with a reducing atmosphere containing hydrogen sulfide, mercaptan or another sulfur containing compound at high temperature. Catalyst 9 may be sulfidated in situ by contact with a sulfur-containing feedstock or prior to contact with the feedstock by subjecting it immediately after calcination to a reducing atmosphere containing a sulfur-containing feedstock. a sulfur compound.

Optionally, such a phosphorus compound can be introduced into the catalyst. The phosphorus introduction can be carried out either by adding a phosphorus-containing compound to the carrier materials before forming the particles or by adding phosphoric acid to the impregnated solution. The phosphorus is usually present in the catalyst in an amount of from 1 to 30 J, preferably from 3 to 15% by weight, calculated as P _o 0 · ₅ .

Boron may still be present in the catalyst composite. The boron can be introduced into the composite either in elemental form or in the form of any boron compound and by any of the methods described above. Thus, it can be introduced into the catalyst during the particle forming step, or it can be added in the form of a compound, such as boronic acid, to the impregnation solution. Bor can also be introduced into the crystalline lattice of zeolites. In the latter case, the Y-type oolite is modified to form a silica-alumina-boron zeolite.

The above catalysts are particularly suitable for hydrocracking a hydrocarbon feed to a more valuable lower boiling and lower molecular weight product. The catalysts are particularly useful for the production of medium boiling distillation fractions, i.e. the hydrocarbon fraction boiling from 149 to 371 ° C, as determined by a suitable ASTM test procedure. In addition, the above catalysts are also useful for hydrogenation reactions, such as hydranedrification and hydrodosulfurization. Typical feedstocks include virtually all heavy mineral and synthetic oils and their fractions. Suitable raw materials are, therefore, gas oils from direct distillation, vacuum gas oils, degummedized oils, atmospheric distillation residue, asphalted vacuum distillation residue, coking distillates, catalytic cracking distillates, slate oil, tar sand oil, liquefied coal and the like. Preferred feedstocks are gas oils, of which at least 50 volume components have boiling points above 371 ^and C. The hydrocracking batch may contain nitrogen, which is typically present in the form of organic nitrogen compounds in an amount ranging from 1 ppm to 1.0%. weight. The seed usually contains sulfur-containing compounds in an amount corresponding to a sulfur content above 0.15 (6 wt.%). It may also contain mononuclear and / or multinuclear aromatic compounds in an amount of 80% by volume or higher.

CS 276 113 QC

The process of the invention operates under analogous hydrocracking conditions to those conventionally used in the art. The hydrocracking reaction temperature is in the range of from 204 to G49 ° C, preferably from 31G to 510 ° C. The reaction pressure is in the range of atmospheric pressure to about 24 MPa, preferably in the range of 1 to 21 MPa. The contact time usually corresponds to an hourly liquid phase space velocity (LHSV) of from about 0.1 to h -1, preferably from about 0.2 to 3 h * ^-1 . The rate of hydrogen circulation is in the range! from 170 to 0390; preferably from 355 to 5330 nm / m of feed.

The reaction zone stream is usually withdrawn from the catalyst bed, partially condensed, separated by aa liquid from steam, and the liquid fraction is fractionated to obtain a variety of its components. The hydrogen and optionally some or all of the heavier substances converted are recycled to the reactor.

Accordingly, the present invention can be characterized as a hydrocracking process selectively directed to medium-boiling distillate, characterized in that a stream of hydrocarbon feed containing at least 50% by volume of components boiling above 371 ° C is contacted with a catalyst consisting of a) hydrogenation component, b) matrix and (c) a crystalline aluminosilicate zeolite in a hydrogen form having a basic X-ray diffraction pattern corresponding to a Y zeolite diffraction pattern, an ion exchange capacity greater than 0.07, an elemental cell size in the range of 2.420 to 2.440 nm, and an NH acidity value ? -TPD is less than 1.50, wherein; the zaolite was treated by contacting 3 with water vapor at a temperature of about 67 ° C to about 700 ° C for a period of from about 2 to about 12 hours, and was then hydroxylated by dry calcination at a temperature of at least about 42 ° C for at least one hour; wherein the catalyst is maintained under hydrocracking conditions and product stream is removed.

The examples are merely illustrative and are not to be construed as limiting the scope of the invention.

Example 1

In this example, the effects of two different zeolite acid reduction techniques are compared. In process A, the starting zeolite is heated in the presence of water vapor, and then the 3-st. The acidity of the zeolite is determined by the above NH ₃ -TPO test. The crystalline lattice of the starting zeolites contains silica and alumina in a ratio of 5: 1 to 0: 1. The preferred silica to alumina ratio is α3i 6 s 1. This ratio is not equivalent to the bulk ratio of silica to alumina. links sometimes referenced. The zeolites contain less than 0.1% sodium by weight.

Procedure

Samples of ammonium-exchanged type Y zeolite, previously sold by Union Carbide Corporation and now sold by UOP (referred to in the literature as LZ-Y02), are used. The zeolite and an initial NHg-TPD acid value of 2.50 and an elemental cell size of 2.45G nm were placed in a heating tube equipped with an external heating device. Depending on the desired acidity value, the salt is brought into contact with pure water vapor formed from demineralized water at an absolute pressure of 1 bar and at a temperature of 67 ° C to 733 ° C for 2 to 12 hours. At the end of the selected heating period, the steam flow is stopped and the batch temperature is lowered to room temperature in a dry air stream for more than 4 hours. During this step, the zeolite is maintained at a temperature of at least 42 ° C for at least 1 hour.

Five zeolite samples (A, B, C, D, and F) were prepared as described above, and the temperatures and times used are shown in Table I. The analysis confirms that samples of these products have an X-ray diffraction pattern corresponding to Y zeolite. The NH 4 -TPD acidity of these samples is shown in Table I.

The results show that the acidity of the zeolite can be reduced (reduced) to a predetermined hour

CS 276 113 33, the elemental cola being in the desired range of 2,420 to

2.440 nm. Thus, the acid value of NH4 -TPD can be adjusted by process A, which involves dry calcination after steam treatment.

Table I

sample processing conditions velikosts acidity zeoli tu steam elementary (mol time (h) temperature (° C) cells (nm) FIH ₃ / g)

AND 2 67G 2,430 1.50 (B) 2 732 2,435 1.13 C 2 708 2,429 0.55 0 12 700 2,425 0.14 £ - 2,436 1.30 F 6 075 ' 2,435 1,25

Procedure B

It is used with ammonium-exchanged Y-type powdered oolite sold by Union Carbide Corporation and is now sold by UOP (referred to in the literature as LZ-20). A zeolite having an initial Mllg-TPD of 2.18 and an elemental cell size of 2.437 nm is charged to a muffle furnace (no water vapor is present in this procedure). The starting material represents a representative of the class of known zeolites used after steam treatment for selective catalysts for the production of medium-boiling hydrocarbon distillates, see for example US patent S. 4,419,271. hours and then allowed to cool to room temperature. Analysis showed that the product showed a typical X-ray powder diffraction pattern of the oolite Y, had an elemental cell size of 2.43Gnm, and an MHg-TPQ acidity value of 1.30. In Table 1, this zeolite is indicated by the letter E.

The results show that dry calcination reduced the acidity of fJH ₃ -TPD zeolite E without significant effect on elemental cola size.

In this context, it should be noted that in process A, both the size of the elementary cell and the NH 4 -TPD acidity of the starting zaolite have changed. However, in process B30, the acid value of NH3-TPO only decreased, while the size of the starting cell of the starting zeolite remained substantially maintained (from 2.437 nm to * 2.435 nm).

Thus, heating or calcining the zeolite at high temperature in a relatively dry environment, such as a stream of nitrogen-containing gas, in the absence of water vapor, is an effective way to reduce the hydroxy group concentration of the zeolite. Thus, this technique can be included in general catalyst preparation processes wherever such low acidity or low hydroxyl concentration is to be achieved.

Without wishing to be bound by theory, it is believed that the acidity is independent of the size of the elementary cell and can be customized by various combinations of heating in the presence of steam and dry air. However, the beneficial effect of heating with and without steam on the acidity of the zeolite is unknown.

In a preferred process, a hydrogen form of zeolite is produced which has a substantially unchanged size of the elemental cell relative to the unmodified zeolite. The above-mentioned calcined calcination for dryness is used extensively as the only means for reducing the acidity and concentration of hydroxy groups in the zeolite. If other methods, such as dealumination or ion exchange, are used, these processes are preferably applied prior to dry heat treatment. Dohydrot

CS 276 113 BG 10 xylation 9β is preferably performed prior to introduction of the treated zeolite into the formed catalyst particles.

It is believed that in hydrothermal treatment, steam tends to prevent dehydroxylation of zeolite. The use of steam It is obviously appropriate if the processing of the elemental cell of the zoolite is to be resized. Thus, in the process of the invention, zeolite with a reduced concentration of hydroxy groups and not simply steam-treated zeolites is used.

Many oolites used in prior art catalysts are characterized by water adsorption capacity. This feature and its determination are described in previously incorporated U.S. Pat. No. 4 401 556 are characterized by a Zenlity adsorption capacity for water vapor at 25 ° C and p / p ₀ of 0.10 below 5.00% by weight. These values were not measured for the substances tested in these examples. Later, however, substances treated in a similar way and coming from the same sources were subjected to this test. The corresponding zeolite C and treated with the same hydrothermal process (used in Catalyst 3 below) had a water adsorption capacity of about 2.5% by weight. Unedited outcrop! the process A substance (Cat. No. 7) had a water adsorption capacity of about 10% by weight. The starting material value for Procedure 3 was not determined. The adsorption capacity for water appears to decrease proportionally with the intensity of the hydrothermal treatment.

Example II

The purpose of this example is to determine the effect of elemental cell size and NHg-TPD acidity on the selectivity and activity of the resulting catalysts.

Catalysts are prepared by mixing the powdered zeolite with a matrix of a refractory oxide composed of alumina and silica-alumina in amounts selected to give a catalyst containing 5% by weight volatile free zeolite and 95% by weight oxide matrix. The resulting mixture was squeezed out! for cylindrical bodies with dimensions 0.16 χ 1.27 cm. The extrudate was dried and then calcined in air at 343 ° C for two hours. The calcined particles are then co-impregnated by evaporative deposition with an aqueous solution of ammonium meta-tungstate and nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O), which are present in amounts sufficient to provide a catalyst containing 1.0 wt. 0% by weight of elemental tungsten. The impregnated catalyst is then calcined at 343 ° C for 45 minutes and then at 593 ° C for 90 minutes. Six catalyst compositions are prepared as described above, each containing one of the zeolites Y prepared according to Example I. Table II lists the properties of catalysts 1 to 6 corresponding to the zolites A to F.

The above catalysts were prepared using the zeolites used as starting materials in procedures A and 3 in Example I. Catalyst # 7 was prepared using the starting zeolite for Procedure A (elemental cell size 2.456 nm, NH 4 -TPD and 2.60) and Catalyst No. 8 was prepared using the starting zeolite for Procedure B (elemental cell size = 2.437 nm, NHg-TPD = 2.18). The properties of catalysts 7 and 0 are also shown in Table II.

Table II

catalyst C. zeolite elementary cell size (nm) nh value ₃ -tpo 1 Λ 2,43G 1.50 2 (B) 2,435 1.13 3 C 2,429 0.65

EN 276 113 BG continued Table II

catalyst C. zeolite elementary size cell (nm) nh value ₃ -tpd 4 D 2,425 0.14 5 E 2,436 1.30 6 F 2,435 1,25 7 default! substance for process 2,456 2.60 8 starting material for process B 2,437 2.18

All of the above ee catalysts were tested for activity and selectivity as follows. The preheated gas oil which has chemical and physical properties shown in Table III, science isothermiekým reactor (single pass) containing 75 ml of catalyst particles mixed with about 29 ml of a silica having a grain size from 60 to 00 mesh _(from 180 to 250 microns). It is operated under these operating conditions; overpressure 13.79 MPa, hourly space / 3 3 m liquid phase velocity 1.0 h, recycled hydrogen flow rate 1770 Nm / m at a purity of 90-95%, and experiment duration approximately 4 days. The reactor temperature is adjusted to achieve 85% (w / w) conversion to products boiling below 371 ° C. To _the nVersion in% is calculated based on the analysis of the range! boiling point of the product by liquid chromatography.

Table III

Properties of vacuum gas oil

density at 15.6 ° C (g / cm ⁶ ) 0.9248 distillation (° C) density ° API at 15.5 ° C 21.5 beginning 200 pouring temperature (° C) 26.7 5/10% 340/372 aniline point (° C) 75.0 20/30 398/419 sira (LEČO), (J mass) 2.24 40/50 439/455 Nitrogen (Kjsldahl), (ppm) 1100 60/70 473/490 carbon weight) 85.82 00/90 514/544 hydrogen (? □ weight) 11.64 end 582 bromine number 5.0 % of the distilled product 99.0 Viscosity at 98.9 ° C (m ^ / s) 6,954.10 ^-6 carbon (Condradson) (% by weight) 0.42

The results of the above test are shown in Table IV. Catalysts 1 to 4 and 6 are prepared from the compound of Example I, Poetup A.

CS 276 113 BG

Table IV

catalyst C. Activity, (° C) (reactor temperature required to achieve 85% conversion) Selectivity (% by weight of the product with a boiling point of 149 to 371 ° C at 85% conversion) nh value ₃ -tpd 1 412 59 1.50 2 414 59 1.13 3 419 61 0.65 4 425 63 0.14 5 417 80 1.30 6 417 59 1,25 7 405 55 2.60 8 417 5G 2.10

The data also show that the catalysts of Examples I to IV of the present invention are significantly better in combination of activity and selectivity than the catalysts of Examples 7 and 8, which contain untreated highly acidic catalyst. A comparison of catalysts 1 to 6 and 7 and 8 shows that a better catalyst is obtained when the NH 4 -TPD acidity of the zeolite component is less than about 2.0. In particular, although Catalyst No. 7 exhibits a relatively high activity (405 ° C), its selectivity is unacceptable (55% by weight). However, it should be noted that the size of the elemental cell of the zeolite contained in Catalyst No. 7 is 2,456 nm, a value which lies outside the preferred range. 2,420 to 2,445 nm disclosed in previously cited U.S. Patent No. 4,401,556.

Catalyst No. 8, containing zeolite, whose elemental cell size lies within the above range (2,437 nm), however, exhibits comparable activity (417 ° C) but poor selectivity (56% by weight). From the above examples, it is clear that the acid value of the NH 4 -TPD zeolite component affects the overall performance of the hydrocracking catalyst.

The starting zeolite from process S, as described above, appears to exhibit a number of preferred properties described in reference to U.S. Pat.

401,556 (Bezman et al.). It is a commercially available substance with a unit cell size of 2.377 nm, which has been subjected to hydrothermal treatment. A seventh exception to the zeolite of the present invention with respect to the preferred properties cited in this reference is its ion exchange capacity value, as determined by Bezman et al. (0,171). This substance is used in Example S. Bezman's reference states that the ion exchange capacity should not exceed 0.07.

Dry calcination converts the substance used in Catalyst 8 to the substance used to prepare Catalyst 5. Catalyst 5 has better selectivity with the same activity and is an excellent catalyst. The difference in elementary cell size between zeolites in catalysts and δ is practically insignificant. 3a, it can therefore be seen that the selectivity of the catalyst in this manner can be improved by substantially more than would correspond to a change in the size of an elemental cell. The zeolite E used in the excellent catalyst 5 has an ion exchange capacity of 0.091. This is a value that exceeds the upper limit quoted in the Bezman reference cited above and has increased by 28%.

Claims (1)

PATENT CLAIMS A process for hydrocracking a hydrocarbon feed stream comprising at least 50 volume components boiling above 371 ° C to produce a medium boiling hydrocarbon distillate having a boiling point of 147 to 371 ° C, wherein the feed stream is contacted with a catalyst comprising a hydrogenation component selected from molybdenum, tungsten, nickel, cobalt, platinum, palladium and iron, an inorganic matrix containing 45 to 90% by weight of silica-alumina and 5 to 45% by weight of alumina and zeolite type Y in hydrogen form having a unit cell size of 2,420 to 2,440 nm under hydrocracking conditions comprising a temperature of 204 to G49 ° C, an overpressure of 1379 to 20S05 kPa, a liquid phase space velocity of 0.1 to 15 h and a hydrogen circulation rate of 355 to 5333 Nm, h, characterized in that 9Θ uses a catalyst, having a zeolite component having an ion exchange capacity greater than 0.07 and an acid value of NHg-TPD lower than 1.50