EP0073690B1 - Catalytic hydroconversion process of heavy hydrocarbons in the presence of a dispersed catalyst and of carbonaceous particles - Google Patents

Description

The present invention relates to a process for the catalytic hydroconversion of heavy hydrocarbon feedstocks containing asphaltenes and metallic impurities, sulfur and nitrogen.

• a) d'au moins un composé de métal catalytique en solution ou dispersion, avec
• b) des suies constituées de particules appelées cénosphères provenant de la combustion de charges lourdes d'hydrocarbures, contenant des composés de métaux, notamment des composés de vanadium, nickel et fer. Ces suies représentent un élément catalytique bon marché.

This process uses as a catalytic system a combination:

• a) at least one catalytic metal compound in solution or dispersion, with
• b) soot consisting of particles called cenospheres originating from the combustion of heavy hydrocarbon charges, containing metal compounds, in particular compounds of vanadium, nickel and iron. This soot represents a cheap catalytic element.

The catalytic system of the invention leads, under the conditions of hydroconversion, to the transformation of a portion of the heavy products of the feedstock into products with a lower boiling point and significantly lowers the content of impurities by hydrodemetallization, hydrodesulfurization and hydrodenitrification as well as the value of the Conradson carbon residue.

Another important advantage of the presence of the cenospheres is to allow, at the end of the reaction, easy filtration of the catalyst residues (a) present in the liquid product of the reaction.

• a) un composé solide de métal catalique formé in situ à partir d'un composé de ce métal soluble dans la charge d'huile lourde, avec
• b) des particules charbonneuses ou des fines en dérivant, provenant de la gazéification de coke,

est décrit dans le brevet US 4 178 227.A process for hydroconversion of hydrocarbon heavy oil feedstocks using as a dispersed catalyst the combination of:

• a) a solid compound of catalic metal formed in situ from a compound of this metal soluble in the charge of heavy oil, with
• b) carbonaceous particles or fines derived therefrom from the gasification of coke,

is described in US Patent 4,178,227.

In this patent, the fines entrained by the gas, during gasification, have an average size of less than 10 _μm . They contain the metals from the oil, usually vanadium, iron and nickel, and, in addition, the metallic component of the oil-soluble catalytic metal compound which had been added.

US Patent 4204943 describes a catalytic hydroconversion process in which the catalyst consists of carbonaceous or fine particles by deriving whose diameter is less than 10 μm. These particles and fines come from the gasification of coke.

US Pat. No. 4,227,995 describes a catalytic hydrodemetallization process in which the catalyst consists of particles of calcined coke or of "green coke" having a porosity of less than 0.3 cm ³ / g and a specific surface smaller than 5 m ² / g, 50 to 80% of the pores having diameters greater than 10,000 Angstroms (1 µm).

US Pat. No. 4,299,685 describes a process for hydrocracking heavy oil, the catalyst of which consists of fly ash; fly ash are particles with a high mineral content and low carbon content; under the electron microscope, they have a smooth appearance. Their porosity is low, of the order of 0.3 to 0.4 cm ³ / g.

It has been discovered that the use of at least partially substantially spherical carbonaceous particles, called cenospheres, originating from the combustion of industrial heavy fuels, in combination with a metallic compound dissolved or finely divided in the feed, constitute an effective hydroconversion catalyst. heavy hydrocarbon feedstocks with very good yields in conversion of heavy products into lighter products, in hydrodemetallization, in hydrodesulfurization and in hydrodenitrification.

The specific characteristics of these cenospheres make it a very efficient and inexpensive material for transporting insoluble materials and the metals formed during hydroconversion. Their high content of metals (Fe, Ni, V) (approximately 1 to 10% by weight, in total, of at least one of these three metals) also gives them a catalytic activity of cracking, hydrogenation and demetallation. . Finally, their roughly spherical shape and their relatively large size ensure their easy removal by filtration without clogging the filters.

Preferably, the representative cenospheres used contain, by weight, from 0.1 to 2% of vanadium (preferably 0.4 to 2%), from 0.1 to 5% of iron (preferably 0.4 to 2% ) and from 0.2 to 1% of nickel (preferably 0.5 to 1%), these values not being limiting.

They also contain carbon, for example 60 to 90% by weight, and sulfur, for example 2 to 10% by weight, as well as common elements such as Na and Ca.

The specific surface of the cenospheres can be very variable, most often between 2 and 130 m ² / g, preferably 2 to 20 m ² / g.

• La figure 1 est un agrandissement de 400 fois d'un groupe de cénosphères.
• La figure 2 est un agrandissement do 1000 fois d'un groupe de cénosphères.

The cenospheres, examined under an electron microscope, have a porous structure, similar to that of pumice or a sponge.

• Figure 1 is a 400-fold magnification of a group of cenospheres.
• Figure 2 is a 1000-fold magnification of a group of cenospheres.

It is generally accepted that the cenospheres result from cracking of the fuel droplets. They are therefore distinguished from elementary soot particles whose size is only a few hundred angstroms (1 A = 10- ¹⁰ meters), although these particles may agglomerate in the form of much longer strings.

The average diameter of the cenospheres is usually greater than 10 μm, for example between 10 and 200 μm or between 20 and 200 μm, more particularly between 20 and 60 μm.

Their grain density is usually from 0.3 to 0.8 g / cm ³ , preferably from 0.4 to 0.6 g / cm ³ , and their structural density usually from 1.2 to 2.5 g / cm ³ , preferably 1.3 to 2.1 g / cm ³ .

Their total porous volume is usually 0.8 to 2.5 cm ³ / g, preferably 1.2 to 1.7 cm ³ / g.

Certain initially spherical cenospheres may have been broken and the invention also covers the use of debris from cenospheres.

Hydroconversion is a process in which a part of the heavy constituents of the charge is transformed under hydrogen pressure, at high temperature, into products with a lower boiling point.

• 1. l'addition à la charge d'hydrocarbures de:
  • a) au moins un composé de métal catalytique, de préférence sous forme d'une solution dans un solvant, par exemple dans l'eau ou dans un solvant d'hydrocarbure, le métal du composé appartenant à l'un au moins des groupes V B, VI B, VII B et VIII, et
  • b) des cénosphères,
• 2. le maintien du mélange résultant dans des conditions d'hydroconversion, et
• 3. le fractionnement des produits obtenus.

According to the invention, the heavy hydrocarbon feedstocks are valued according to a hydroconversion process which comprises:

• 1. the addition to the hydrocarbon load of:
  • a) at least one catalytic metal compound, preferably in the form of a solution in a solvent, for example in water or in a hydrocarbon solvent, the metal of the compound belonging to at least one of the VB groups , VI B, VII B and VIII, and
  • b) cenospheres,
• 2. maintaining the resulting mixture under hydroconversion conditions, and
• 3. the fractionation of the products obtained.

• - les pétroles bruts et les fractions dérivées de ces pétroles bruts,
• - les fractions lourdes tirées du pétrole, telles que les résidus de distillation atmosphérique ou sous-vide,
• - les alphates provenant des unités de désasphaltage,
• - les goudrons, bitumes, produits venant des sables et schistes bitumineux,
• - les fractions liquides riches en asphaltènes provenant de la liquéfaction du charbon.

The process which is the subject of this invention is applicable to hyrocarbon heavy fillers containing asphaltenes and metallic impurities, sulfur and nitrogen. These heavy loads include:

• - crude oils and fractions derived from these crude oils,
• - heavy fractions from petroleum, such as atmospheric or vacuum distillation residues,
• - alphates from deasphalting units,
• - tars, bitumens, products from tar sands and oil shales,
• - liquid fractions rich in asphaltenes from the liquefaction of coal.

This process is particularly well suited for the heaviest hydrocarbon feedstocks having a Conradson carbon residue of up to 50% by weight. These fillers also have very high contents by weight of asphaltenes (for example up to 40%), sulfur (for example up to 8%) and metals (for example up to 3000 ppm).

The catalytic metal compound used in the invention is a finely divided metallic compound preferably originating from a metallic compound soluble in the charge or from an aqueous solution of a metallic salt which is dispersed in the charge or, intermediate, in a hydrocarbon solvent.

• - les composés métalliques inorganiques tels que les halogénures, les oxyhalogénures, les polyhé- téroacides, par exemple: acide phosphomolybdique, bleus de molybdène, acide alkyldithiophos- phorique,
• - les sels métalliques d'un acide organique, aliphatique, naphténique ou aromatique, d'un acide sulfonique, d'un acide sulfinique, d'un acide xanthique, d'un mercaptan, d'un phénol ou d'un composé aromatique polyhydroxylé,
• - les chélates métalliques, tels que les complexes 8-côtoniques, les penta et hexacarbonyls, les complexes avec l'éthylènediamine, l'acide ethylènediaminetetracétique, les phtalocyanines,
• - les sels métalliques des amines organiques et des sels d'ammonium quaternaire.

The metallic compound soluble in the filler can be chosen from:

• - inorganic metal compounds such as halides, oxyhalides, polyheteroacids, for example: phosphomolybdic acid, molybdenum blues, alkyldithiophosphoric acid,
• - the metal salts of an organic, aliphatic, naphthenic or aromatic acid, a sulfonic acid, a sulfinic acid, a xanthic acid, a mercaptan, a phenol or a polyhydroxy aromatic compound ,
• - metal chelates, such as 8-ribonic complexes, penta and hexacarbonyls, complexes with ethylenediamine, ethylenediaminetetracetic acid, phthalocyanines,
• - metal salts of organic amines and quaternary ammonium salts.

The metallic constituent of these soluble compounds convertible into a solid dispersed catalyst belongs to groups VB, VI B, VII B and or VIII according to the table published by EH Sargent in 1962. The preferred metals are molybdenum, vanadium, chromium , tungsten, manganese, iron, nickel, cobalt. The preferred compounds are molybdenum naphthenate and molybdenum blue.

The amount of the soluble metal compound added to the charge is for example between 10 and 1000 ppm, preferably between 50 and 500 ppm counted by weight of metal relative to the charge.

The metal compound can be added either alone or mixed with one or more compounds of different metals.

The metallic compound, dissolved in an aqueous solution optionally pre-emulsified with a hydrocarbon, can be for example: ammonium or alkali metal heptamolybdate, cobalt nitrate, nickel nitrate, ferrous sulfate or sodium tungstate.

The preferred compound is ammonium heptamolybdate either alone or as a mixture with another metallic water-soluble compound.

The amount of metallic compound dissolved in the emulsified aqueous solution is between 10 and 1000 ppm, preferably between 50 and 500 ppm counted by weight of metal.

The cenospheres most often come from smoke dedusting installations in large thermal power plants burning heavy industrial fuels, in particular heavy No. 2 fuels.

These cenospheres are mixed with the filler in the proportion of 0.1 to 5% by weight relative to the latter.

The filler containing the cenospheres, the soluble metallic compound or the metallic salt provided by an aqueous solution or emulsion may or may not be subjected to a pretreatment.

The purpose of this pretreatment is to transform the metal compound or the metal salt into a finely dispersed solid catalyst comprising from 10 to 1000 ppm, preferably from 50 to 300 ppm by weight of active material counted as elemental metal, based on the weight of filler . The pretreatment is carried out in the presence of hydrogen sulfide alone or in admixture with hydrogen at a temperature between 200 and 450 ° C and under a pressure between 25 and 250 bars. During this pretreatment, some or all of the metals contained in the cenospheres are also transformed into metallic sulphides.

When there is no pretreatment, the charge mixed with the constituents of the catalytic system is sent to the hydroconversion reactor where the metallic compound or the metallic salt and the metals contained in the cenospheres are transformed into metallic sulfides under the action feed sulfur and / or sulfur compounds formed during the reaction, especially H ₂ S.

FIG. 3 describes an embodiment of the method given by way of example.

The fresh charge, the soluble metallic compound or the emulsion of an aqueous solution of a metallic salt in a hydrocarbon are introduced respectively by lines 1, 2 and 3 into a mixing tank 4.

This mixture is pumped, line 5, into a pretreatment reactor 6, where it is brought into contact with hydrogen containing from 2 to 10% of hydrogen sulfide. Hydrogen is a mixture of fresh hydrogen (line 7) and recycled hydrogen (line 8). The hydrogen sulphide is supplied either by recycling (line 8), or by a fresh supply (line 9). For this pretreatment, the temperature is between 200 and 450 ° C, preferably 350/450 ° C, the pressure between 25 and 250 bars, preferably 100/200 bars, the reaction time between 5 minutes and 4 hours, from preferably 10 minutes to 2 hours.

The pretreated product is introduced (line 10) into the hydroconversion reactor 11. The temperature of this reactor is between 380 and 480 ° C, preferably 420 to 460 ° C, the partial pressure of hydrogen between 25 and 250 bars , preferably between 100 and 200 bars, the hydrogen flow rate between 1000 and 5000 liters TPN / liter of charge, preferably between 1000 and 2000 I / I and the space speed (VVH) defined by the charge volume per hour and per reactor volume between 0.1 and 10, preferably between 0.25 and 5.

The effluent which leaves the hydroconversion reactor via line 12 comprises gases and a liquid having solids in suspension. It is introduced into a high pressure separator 13. From this separator leaves a gas (line 14) which contains hydrogen, hydrogen sulfide and light hydrocarbons. Part of this gas is recycled, after treatment to remove the hydrogen sulfide, to the pretreatment reactor or the hydroconversion reactor if there is no pretreatment. The other part is eliminated (28) to maintain the partial pressures of hydrogen and hydrogen sulfide at the fixed level.

Via the line 15, a liquid product with suspended solids is drawn off through an expansion valve.

To treat this mixture, it is possible to use different treatments, using known technologies. These differ according to the characteristics of the charge, the severity of the hydroconversion, the use of the finished products, for example.

Indicative title, is given a processing mode represented in figure 3 attached.

The liquid product, coming from the separator 13 through line 15, passes through a low pressure separator (not shown) where a water purge can be made. It is then introduced (line 15) into a fractionation unit 16, from which one or more fractions (17 and 29) are removed.

This fractionation unit can be a simple vacuum evaporator or a vacuum distillation column. The adjustment of the separation between distillate and residue is done to obtain a flowable and pumpable residue under industrial conditions.

The residue drawn off through line 17 is mixed in tank 18 with an aromatic solvent with a boiling point of between 100 and 220 ° C., introduced through line 25. This solvent reduces the viscosity and allows a phase to be obtained. which is treated in a separation unit 20, joined at 18 by line 19. In this separation unit, the solids are separated by filtration or centrifugation or decantation.

The filtered or centrifuged solids are washed with the same aromatic solvent (line 26), in the separation unit 20, to remove the oily products which coat the sulfides of the metals. catalytic, the metal sulfides contained in the charge, the cenospheres more or less charged with metals and metallic sulfides and the insoluble in the aromatic solvent.

A fraction of these solids is eliminated via line 21. They can be burned, carbonated or treated in order to recover the metals. The other fraction is recycled to the hydroconversion reactor (line 22), this via the mixing tank 4, the residual aromatic solvent can either be kept or eliminated.

The liquid phase coming from the separation unit 20, mixed with the washing solvent, enters via the line 23 into a distillation unit 24.

At the head of this unit, the aromatic solvent is withdrawn, which is reinjected into the mixer 18 through line 25, and into the separation unit 20, through line 26, for washing the filtered or centrifuged solids. At the base of the distillation column 24, the hydrotreated residue (conduit 27) leaves, largely free of metals, sulfur, nitrogen and asphaltenes. This residue is either burned, or gasified, or diluted to make a heavy fuel oil No. 2.

It should be noted that with the recycling of part of the solid products coming from the separation unit 20, it is possible either to reduce, or even to suspend intermittently, the introduction with the charge of fresh metallic compound. The quantity of this fresh metallic compound will be chosen according to the level of activity desired.

Example Experimental procedure a) Batch test

A 250 ml stainless steel autoclave is used. The gas-liquid contact is ensured by shaking.

A test is made with 30 g of filler. The autoclave, after loading the soluble molybdenum compound, the cenospheres and the charge, is closed and weighed at atmospheric pressure, scanned with hydrogen and subjected to a hydrogen pressure of 100 bars for one hour to check the sealing.

The autoclave, filled with hydrogen at 100 bars at room temperature is brought to the test temperature, in 3/4 hour to 1 hour depending on the temperature. The reaction time corresponds to the temperature level. Cooling is done in the open air.

In the case of pretreatment, the autoclave is first filled with hydrogen sulphide at 10 bars, then it is completed up to 100 bars with hydrogen. The mixture is heated to 380 ° C., left for 1 hour, cooled to room temperature, relaxed, scanned with hydrogen and then the test is repeated as indicated above.

After cooling the autoclave is depressurized. The gases are washed with soda, measured in a counter and analyzed by gas chromatography.

The reaction medium is diluted with toluene and filtered. The solids are washed with hot toluene. The two toluene solutions, for filtration and washing, are evaporated at 100 ° C. under 0.025 bar. The hydrocarbons entrained with toluene are analyzed. The evaporation residue constitutes the hydro-converted product.

The weight balance must be greater than 95% for a test to be considered valid.

b) Continuous test

The charge containing the soluble metallic compound and the cenospheres is mixed in line with hydrogen containing from 3 to 7% of hydrogen sulfide, then is brought to the reaction temperature through an oven, consisting of five heating elements. It then enters the bottom of a reactor, consisting of a vertical tube. The reactor effluent is cooled to 150 ° C and passed through a high pressure separator. The gas from this separator is recycled after being washed with water. A purge allows the partial pressures of hydrogen and hydrogen sulfide to be adjusted. The hydroconverted product is drawn off at the base of the high pressure separator.

Les cénosphères présentaient les caractéristiques suivantes:

Two charges were used in the examples (Table I); these are a Safanya vacuum residue and an asphalt, coming from a pentane deasphalting unit of the same vacuum residue; this asphalt is diluted with 35% by volume of diesel.

The cenospheres had the following characteristics:

Example 1

The operation is carried out batchwise with 30 g of Safanya asphalt diluted with 35% by volume of diesel oil at 420 ° C. for two hours; initial hydrogen pressure: 100 bars; no pretreatment. Various tests are carried out: test without catalyst, test with cenospheres alone, test with molybdenum naphthenate alone, test with molybdenum naphthenate plus cenospheres.

Table II brings together the results provided by these tests.

The addition of cenospheres to molybdenum naphthenate therefore improves, in a very significant way, the demetallation without appreciably increasing the amount of insoluble matter.

The cenospheres alone, test 301, compared with test 278, only thermal, already exhibit a hydrogenating and desulphurizing activity, as shown by the C ' _{3 /} C ₃ ratio and the percentage of hydrodesulfurization.

The cenospheres allow the fixation of vanadium, nickel and molybdenum.

Molybdenum is not found in the liquid hydroconverted product.

Example 2

The tests indicated in this example are carried out under the same conditions as in Example 1. A molybdenum blue in 5.8% solution in a C ₇ -C ₉ alcohol is used as the molybdenum compound.

Table III collates the results of these tests.

These tests confirm the results obtained with molybdenum naphthenate, namely the presence of cenospheres increases the hydrometallation activity and reduces the weight of insoluble matter.

Example 3

The procedure is as in Example 1, but adding to the hydrocarbon feedstock, in addition to cobalt naphthenate and the cenospheres, 0.5% by weight, relative to the feedstock, of cenospheres recovered at the end of the Example 1 and washed with hot toluene. The addition of these recovered cenospheres makes it possible, as shown in Table IV, to reduce the supply of fresh molybdenum naphthenate to 100 ppm, without significant modification of the results.

Example 4

We operate according to the continuous method described above with the vacuum residue Safanya.

The charge is mixed with molybdenum naphthenate (500 ppm by weight of molybdenum) and 1% by weight of cenospheres, identical to those used in Example 1. It is introduced into the preheating oven at the rate of 1 liter / h , where it is brought to 430 ° C, the temperature at which it enters the reaction chamber.

The total pressure is 150 bars. The recycled hydrogen is introduced online just before the preheater, with an H _{2 /} Hydrocarbon ratio equal to 1000 liters per liter, the hydrogen being considered at normal temperature and pressure. Hydrogen contains 2 to 3% hydrogen sulfide. The space velocity, charge volume per hour and per reactor volume, is equal to 1.2, which corresponds to a residence time in the reactor of 54 minutes.

Table V shows the results obtained after 100 hours of operation under the preceding conditions.

Example 5

We operate according to the continuous method described above with a Safanya asphalt diluted with 50% of »Iight cycle oil«. The resulting mixture has the following characteristics:

Two tests are carried out under strictly identical operating conditions, indicated in Table VI.

In the first test (111), molybdenum naphthenate is used alone, in the second test (112), 2% by weight, relative to the charge, of cenospheres are added to the molybdenum naphthenate.

For each test, a 24-hour review was carried out at 405 ° C, 417 ° C, 430 ° C. On the hydroconverted products drawn off at the base of the high pressure separator, filtration tests were carried out under the following conditions:

Table VI provides the filtration rates for these different products as well as their viscosity at 50 "C.

It appears very clearly that for identical filtration conditions and for almost similar viscosities, the presence of the cenospheres, described above, promotes filtration and therefore the separation of the catalyst with a view to possible recycling. It is as if these carbonaceous particles act as a filter aid.

For comparison, the filtration times observed with other filtration aids were given. Only Celite (registered trademark) gives equivalent results; the advantage of the cenospheres, after use, is that they can be burned.

Claims (9)

1. A process for converting a heavy hydrocarbon charge containing asphaltenes and metal, sulfur and nitrogen impurities, in order to obtain products of lower boiling point and lower impurities content, wherein a mixture of said charge with hydrogen is contacted with a catalyst characterized in that the catalyst comprises at least two essential elements:

a) soot of the cenosphere type, resulting from the combustion of liquid heavy hydrocarbon charges, and containing at least one metal of the iron, nickel and vanadium group, and

b) at least one catalytic metal compound distinct from the element (a) and selected from the compounds of metals of groups V B, VI B, VII B and VIII.

2. A process according to claim 1, wherein element (b) is added to the hydrocarbon charge in the form of a solution in a hydrocarbon solvent, a solution in a non-hydrocarbon solvent or an emulsion of an aqueous solution in a hydrocarbon solvent.

3. A process according to claim 1 or 2, wherein the particles of soot of the cenosphere type have an average diameter of 10 to 200 _!lm and contain 60 to 90% by weight of carbon and 1 to 10% by weight of metals of the iron, nickel and vanadium group.

4. A process according to claim 3, wherein the soot of the cenosphere type contains, by weight, 0.1 to 2% of vanadium, 0.1 to 5% of iron and 0.2 to 1 % of nickel.

5. A process according to any one of claims 1 to 4, wherein the cenospheres have a specific surface of 2 to 130 m²/g, a total pore volume of 0.8 to 2.5 cm³/g, a particle density of 0.3 to 0.8 g/cm³ and a structural density of 1.2 to 2.5 g/cm³.

6. A process according to any one of claims 1 to 4, wherein the cenospheres have a specific surface of 2 to 20 m²/g, a total pore volume of 1.2 to 1.7 cm³/g, a particle density of 0.4 to 0.6 g/cm³ and a structural density of 1.3 to 2.1 g/cm³.

7. A process according to any one of claims 1 to 6, wherein the amount of cenospheres is 0.1 to 5% by weight of the hydrocarbon charge and the amount of element (b) from 10 to 1000 ppm by weight of said charge.

8. A process according to any one of claims 1 to 7, wherein the hydrocarbon charge, after introduction of the two catalyst elements, is treated with hydrogen sulfide, before being subjected or the conversion process.

9. A process according to any one of claims 1 to 8, wherein the metal of compound (b) is selected from the group consisting of molybdenum, vanadium, chromium, tungsten, manganese, iron, nickel and cobalt.

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