RU2563252C1 - Method of producing catalysts for demetallisation of oil fractions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: disclosed method of producing catalysts for demetallisation of oil fractions, which perform the role of protecting a base catalyst in a wide range of hydroforming conditions: from excess adsorption interaction of metal-containing components of the material with the surface of the catalyst to the step for deep conversion thereof. The method includes mixing powdered aluminium oxide, natural aluminosilicate materials, spent nickel-molybdenum-containing catalysts, adding aqueous solutions of molybdenum and nickel compounds, adding hydro-silica sol in amount of 2-12 wt %, adding as a combustible additive wood flour or food-grade flour, as well as a moulding activator, moulding, drying and calcining. The method enables to obtain a set of catalysts with regular reduction of packed density and strength and increase in pore volume in the range of content of hydro-silica sol of 2-12 wt %.

EFFECT: enabling use of catalysts according to the disclosed method as a protective layer in the form of one, two or more layers.

4 cl, 2 tbl, 2 dwg, 8 ex

Description

The invention relates to the refining industry, in particular to catalysts for hydrofining of oil fractions. The efficiency of the catalytic processes of hydrocracking, hydrodesulfurization, hydrodetasification, hydrodearomatization depends on the content of metal impurities in the processed raw materials in the composition of high molecular weight components of asphaltene nature [1. Technology, economics and automation of oil and gas refining processes. Edited by S.A. Akhmetova. M .: Chemistry, 2005].

Target demetallization of heavy and residual fractions of raw materials with a high content of metals occurs under conditions of hydrofining on highly efficient catalysts and is accompanied by desulfurization due to the coexistence of sulfur and metals (for example, nickel and / or vanadium) in the same molecules and their conversion during catalysis [2. V.M. Kapustin, A.A. Gureev. Oil refining technology. Part 2. Destructive processes. M .: Kolos, 2007; 3. USA Patent No. 4196102, 1980].

Sulfur is removed in the form of a gaseous product - hydrogen sulfide, and the metals remain at the site of adsorption or catalysis of the preceding molecules. Under catalysis, products contain components of side processes, usually undesirable.

The accumulation of metals in the porous structure of the catalysts leads to their irreversible deactivation and to reduce the duration of operation.

In advertising materials, the merit of demetallization catalysts is evaluated either by the pore volume or by the weight of metals accumulated in the pores compared to bulk density.

The hydrotreating of middle distillate fractions with a relatively low content of metal impurities is focused on deep desulfurization, deazotization, dearomatization, but is inevitably accompanied by the accumulation of metals in the porous structure of the catalysts.

A characteristic feature of the hydrotreating of middle distillate fractions is the temperature range: from low at the beginning of operation to relatively high by the end of the operation period, but still below the optimum transformation temperatures of metal-containing hydrocarbons.

In general, the conditions are unfavorable for the conversion of organic metal-containing compounds: low temperature and pressure of hydrogen, high space velocity; the role of their physical adsorption on the inner surface of the porous granules of the catalysts increases; accordingly, the requirements for the pore volume and the adsorption properties of the surface of the protective catalysts increase.

The high adsorption capacity of silica gels with respect to asphaltenes and metal-containing impurities in oil fractions is known [4. E.V. Smidovich. Oil and gas processing technology. Part 2. M .: Chemistry, 1980], which allows the use of natural silica gels for the deep purification of oil epaulets and other medium distillate products. Known for the effective use of catalysts based on natural clays of aluminosilicate nature, the use of natural materials containing oxides of manganese and iron [5. USA Patent No. 4045331, 1977].

However, the effectiveness of natural materials in the purification (percolation) of oil fractions, as a rule, is ensured by organizing the process in a separate reactor filled with adsorbent, under conditions optimized for a specific task. The need for deep purification of raw materials with a relatively low content of metal impurities under the conditions of the main hydrofining process in terms of temperature, hydrogen pressure, and contact time puts forward specific requirements for the catalysts of the so-called protective layer and the method for their preparation, respectively. Catalysts with a low bulk density but with sufficient mechanical strength are clearly preferred; with a large pore volume, but also with a sufficient specific surface area, i.e. having macro and micropores; active centers on the inner surface of the pores, preferably of the adsorption type, and simultaneously active centers of the target catalysis process.

Accordingly, it is necessary to optimize the method of producing catalysts for the demetallization of oil fractions under the conditions of a protective layer in the processes of hydrofining of middle distillates.

A known method of producing a catalyst for the hydrofining of hydrocarbon feedstocks containing asphaltenes and heavy metals, based on a carrier consisting of calcined extrudates from a clay mixture consisting of magnesium silicate, with pseudoboehmite, active components from the number of vanadium, chromium, molybdenum, tungsten, cobalt, nickel and copper, as well as auxiliary components used in the synthesis of the carrier from among boron, phosphorus, fluorine and their compounds [6. USA Patent No. 4439312, 1984].

In this case, catalysts containing MoO ₃ up to 14.2%, CoO up to 3.7%, NiO up to 1.5% have a specific surface area of 40 to 188 m ² / g, pore volume from 0.1 to 0.79 cm ³ / g, mechanical properties not shown.

The catalysts used in the processing of raw materials containing up to 6.83% of asphaltenes, up to 4.5% wt. sulfur, up to 505 ppm vanadium, up to 106 ppm nickel, at a temperature of 405 ° C, a hydrogen pressure of 140-168 ati, a space velocity of 0.3-1.0 hour ^-1 , obtaining products with an asphaltene content of up to 0.3% wt. , sulfur up to 0.28% wt., nitrogen up to 0.17% wt., vanadium up to 2 ppm, nickel up to 2.5 ppm, which allows the use of these products as raw materials for cracking and hydrocracking processes to obtain marketable products.

At the same time, very strict requirements on the crystal structure are imposed on pseudoboehmite, which are realized only by complex fixed methods, which exclude the possibility of using the method [6] in practice.

A known method of preparing catalysts for demetallization on media based on natural magnesium silicate (sepiolite) with the addition of boehmite in a ratio of 80:20; 50:50; 20:80. The carriers had a pore volume of up to 0.8 cm ³ / g and a specific surface area of up to 210 m ² / g. Oxides of cobalt, nickel, molybdenum, vanadium, copper, zinc, cerium from aqueous solutions of salts of these elements were introduced into the carriers [3]. The catalysts were used for demetallization of oil fractions containing 2.87% wt. sulfur, 150 ppm vanadium, 41 ppm nickel, 3 ppm iron, at a temperature of 415 ° C, a hydrogen pressure of 140 atm, a space velocity of 1.0 hour ^-1 (examples 1-21). As a rule, the depth of demetallization correlates with the depth of desulfurization and dezotization; When processing raw materials with a metal content of several hundred ppm, products with a low content of metals and sulfur are obtained.

The disadvantage of the method [3] is the low efficiency of the catalysts in the process of demetallization of middle distillate fractions at temperatures of 320-380 ° C and a hydrogen pressure of 30-40 atm, i.e. in the conditions of their hydrofining.

Known methods for regulating the properties of molding sand (for example, the so-called red mud with aluminum-containing compounds [7. US patent No. 4120780, 1978]), including the porous structure of demetallization catalysts, the introduction of organic binders (starch, cellulose), which burn out during calcination.

The disadvantage of the method [7] is the need for calcining the formed granules at a very high temperature, preferably 1100 ° C, which severely limits its applicability.

Known methods for the preparation of demetallization catalysts with a bimodal pore size distribution, controlled by the introduction of additives, such as cellulose or carbon material [8. USA Patent No. 4448896, 1984].

A disadvantage of the known methods is, firstly, the poor formability of the molding sand, the appearance of granules due to scoring, delamination and other defects, and secondly, the regulation of the volume of only large pores and, most importantly, the low strength of the granules.

It is known to use as a protective layer in hydrofining middle distillate fractions of a set of catalysts that differ in pore volume and specific surface [9. USA Patent No. 4306964, 1981]. The catalyst of the upper layer with a total pore volume of 0.4 to 0.65 cm ³ / g and a specific surface area of 90-120 m ² / g has relatively large pores into which metal-containing and hetero-containing molecules of the feed enter and undergo changes (adsorption / catalysis) whereby in the underlying catalyst layer with a smaller pore size comes metallic and geterosoderzhaschie smaller molecules and undergo further changes until complete removal of metals in the lower layers of catalysts having a specific surface of 252-286 m ² / g and concurrently ennym partial desulfurization and denitrification.

However, the method [9] does not describe the preparation of catalysts with different porous structures, forming a series with an increase in specific surface area and a decrease in the average pore size.

The closest in technical essence and the achieved effect to the proposed technical solution is a method of producing a demetallization catalyst [10. Application for invention, RU No. 2008139983/04, 2007], comprising mixing a precursor Al ₂ O ₃ with burnable carbon-containing cotton cellulose fibers with a diameter in the range from 0.5 to 50 μm and a length of not more than 1000 μm in an amount of from 20 to 40% wt. on a.s. (absolutely dry), the addition of nitric acid, extrusion, drying, calcination in two stages: in the range of 350-600 ° C with a content in the atmosphere of not more than 5% vol. oxygen and in the range of 450-600 ° CV when the content in the atmosphere is not more than 12% vol. oxygen. In this case, compounds of molybdenum or tungsten and nickel or cobalt are introduced into the mixture of the Al ₂ O ₃ precursor with burnable carbon-containing fibers, and pseudoboehmite is the precursor of Al ₂ O ₃ .

The disadvantages of this method are:

- the use of a material of fibrous nature as a burnable additive, which, firstly, complicates the preparation of the molding mixture, secondly, reduces the quality of extrudates and increases rejects, respectively, thirdly, leads to the need to calcine the granules in two stages in a fundamentally different atmospheric oxygen content;

- the introduction of only compounds of molybdenum or tungsten and nickel or cobalt, which are active components for the hydrogenolysis of sulfur-containing (and metal-containing compounds under optimal conditions for this process. Beyond these conditions, metal-containing raw material compounds can be retained ("absorbed") on active adsorption centers on the pore surface catalyst In the absence of specific adsorption centers, the effectiveness of catalysts in the demetallization of raw materials under these conditions drops sharply;

- obtaining a catalyst with a very low pore volume: the total pore volume of 0.40 cm ³ / g, while the pore volume with a diameter in the range from 3 to 10 nm is 0.15 cm ³ / g; and the pore volume with a diameter in the range from 100 to 5000 nm is 0.25 cm ³ / g

In general, the catalysts according to the known method [10] have unsatisfactory properties under the conditions of adsorption retention of metal impurities due to the absence of specific adsorption centers and low pore volume.

The aim of the present invention is to develop a method for the preparation of catalysts for demetallization of middle distillate fractions under conditions of their hydrofining, having the functions of adsorption and catalysis of metal-containing compounds with regulation over a wide range of their mechanical properties and characteristics of the porous structure.

This goal is achieved by a method of producing catalysts for the demetallization of crude oil by mixing powders of aluminum oxide precursors and natural materials, introducing active components and burnable additives, molding, drying and calcining, characterized in that the active components include compounds for adsorption of metal impurities and for the conversion of hetero compounds; active components for the hydrogenolysis of sulfur-containing compounds are introduced from aqueous solutions of nickel salts (0.1-1.5% NiO) and molybdenum (0.5-3.0% MoO ₃ ) or in the form of a spent hydrofining catalyst powder containing nickel and molybdenum oxides by kneading in a mixture of a hydrosilicazole alumina precursor; manganese dioxide powder in an amount of 1.0-1.5% wt .; is introduced as a source of adsorption centers of metal-containing compounds; synthetic hydrosilicazole is introduced into the mixture in an amount of 2-12% wt. in terms of a.s .; as burnable additives, wood flour and / or food flour is introduced in an amount of 10-20% wt. on a.s .; as an activator of molding solid fat is introduced in the amount of 4 ÷ 7% wt. on a.s .; as a natural silicate material using materials with a SiO ₂ content _of 30-80% wt .; the alumina precursor preferably contains pseudoboehmite of at least 50% wt. in terms of Al ₂ O ₃ in.with. catalyst, and calcination is carried out at a temperature of 550-600 ° C in an atmosphere containing at least 15% oxygen for at least 10 hours.

The synthesis of catalysts according to the conditions of the proposed technical solution allows to obtain and control the porous structure and mechanical properties in a wide range; (see. Fig.) the pore volume from 0.5 to 0.9 cm ³ / g, bulk density from 0.30 to 0.66 g / cm ³ with a splitting strength of from 1.1 to 3.4 kg / mm .

Below are examples of the implementation of the proposed technical solution, with which it is illustrated, but not exhausted.

I. Synthesis of catalysts

Raw materials and reagents

Aluminum hydroxide with a pseudoboehmite content of 70 ÷ 80% wt. (GOA) Hydrosilicazole

Natural aluminosilicate material with a content of SiO ₂ -30% wt. (clay)

Tripoli Zikeevsky quarry (TZK) with a content of SiO ₂ - 87% wt.

Manganese Dioxide MnO ₂ ≥75%

Spent NiMo Containing Catalyst (NiMo)

Ammonium molybdenum acid (ΝΗ ₄ ) ₆ Μο ₇ O ₂₄ · 4Η ₂ O (PMA)

Nickel nitrate Νi (ΝO ₃ ) ₂ · 6Η ₂ O (ON)

Phosphoric Acid 85% (OFC)

Wood flour brand "180" (DP)

Food flour

Solid oil fat

Chemically purified water (HOV)

I.1. Kneading sand

A method for preparing a mixture of components having satisfactory formability by extrusion on a piston former through 5 mm diameter die (E) and in the form of a trefoil with a height of 1.5 mm (T) consists in sequential mixing and mechanically activated homogenization of a mixture of alumina precursor powder (GOA) and hydrosilicazole by the introduction of aqueous solutions of ammonium molybdenum acid and nickel nitrate and / or water in an amount necessary to obtain a plastic homogeneous mass (A). Powders of natural material containing 30-80% SiO ₂ in an amount of 30-32% wt., Manganese dioxide, spent nickel-molybdenum catalyst, water with mechanically activated homogenization at each stage until a plastic homogeneous mass (B) are introduced portionwise are introduced into this mass. Powder of wood flour or food flour was added to mass B in an amount of 15-25% wt. based on A.S. with the addition of water, if necessary, to obtain the mixture (B). Before molding, fat solidol was introduced into mixture (B) and mechanically activated homogenization was performed to obtain a molding mixture. The pH of the molding sand was 4.3 ÷ 5.8.

I.2. Molding, heat treatment

The moldable mixture according to claim 1.1 was formed by extrusion on a piston former into cylindrical granules through 5 mm diameter die (E) and in the form of a trefoil with a height of 1.5 mm across (T). The extrudates were kept outdoors for 20-24 hours; then dried at a temperature of 80-100 ° C for 6 hours and calcined at a temperature of 550-600 ° C for 10 hours in an atmosphere of air with an oxygen content of at least 15% wt.

II. The quality control of the catalyst at the stages of synthesis

II.1. At the stage of preparation of the molding sand before molding, determine the pH of the aqueous extract and loss on ignition (SPP) at a temperature of 550-600 ° C.

II.2. At the molding stage, the rheological properties of the molding mixture: the absence of thixotropy, the absence of scoring and other defects on the surface of the bundles during extrusion (organoleptically).

II.3 At the stage of dried shamrocks and extrudates: the absence of signs of delamination and other defects on the surface of the granules (organoleptically).

II.4. At the stage of calcined granules: bulk density, strength, pore volume, specific surface.

III. Testing the synthesized catalysts in the process of demetallization of the middle distillate fraction.

III.1 Raw

A straight run fraction with boiling limits of 230-372 ° C, density 0.836 g / cm ³ , sulfur content 0.71% wt., Iodine number 3.9, into which a mixture of vanadium and iron naphthenates was introduced in such a way that the content vanadium and iron in the feed were 180 ppmw and 130 ppmw, respectively.

III.2 Test conditions

The tests were carried out in a pilot installation under conditions of hydrofining of middle distillates, namely, in a hydrogen medium under a pressure of 30 atm with a hydrogen: feed ratio of 350 nl / l, a catalyst loading in the form of particles with a size of 1.0-1.6 mm in a volume of 40 ml. The temperature in the catalyst bed was 320 ° C, 340 ° C, 360 ° C, 380 ° C; volumetric feed rate 1.0; 3.0; 4.0 hour ^-1 .

The effectiveness of the catalysts was evaluated by the residual content of sulfur and metals in hydrogenates and the content of vanadium and iron in spent catalysts.

The following are indicators of the quality of the synthesized catalysts and their effectiveness in the process of demetallization of the middle distillate fraction.

In fig. 1a, b, the dependences of bulk density, strength coefficient, pore volume in water on the content of hydrosilicazole in the range of 2 ÷ 12% wt. by A.S. This interval describes acceptable for use in industry strength values of at least 1.0 kg / mm and bulk density of 0.32-0.62 g / cm ^{3 of} catalysts against a background of a change in pore volume from 0.58 to 0.91 cm ³ / g . The introduction of hydrosilicazole more than 12% wt. leads to a catalyst with a strength factor below 1.0 kg / mm, which excludes its practical use.

Fig. 1 also demonstrates the effect of the molding conditions themselves (holes in the die in the form of a circle of 4.5 mm or a trefoil with a height of 1.45 mm) on the mechanical properties of the product in the range of 2–12% wt. by A.S. under fixed conditions of heat treatment (exposure to air, drying at a temperature of 100-120 ° C, calcination at a temperature of 550-600 ° C in an air environment with an oxygen content of at least 15% wt.).

From the materials of table 2 shows the correlation between the residual content of sulfur and metals in hydrogenates with a change in temperature in the catalyst bed and the volumetric feed rate. With a change in the pore volume of the catalyst from 0.58 to 0.92 cm ³ / g, the residual vanadium content varies from 55.5% to 22.5%, the residual iron content from 65.4% to 23.7%, and the residual content sulfur ranges from 19.8 ÷ 15.3%. The residual sulfur content in the hydrogenates obtained on the prototype catalyst is characteristic of the hydrotreating process of middle distillate fractions on catalysts with a similar content of active components. However, the residual metal content in the same hydrogenates significantly exceeds that in hydrogenated catalysts according to the proposed method, ranging from 56.7% to 70.6%) of vanadium and from 83.1% to 87.7% of iron due to the low adsorption capacity of the known catalyst in relation to metal-containing components.

This is confirmed by comparative data on the content of vanadium and iron in spent catalysts by the proposed method and in the prototype catalyst (table 2). The high metal content of the catalysts according to the proposed method with a pore volume of 0.56-0.92 cm ³ / g is a consequence of an increase in the residence time (contact, retention) of the raw materials, including metal-containing components, in the pores and the presence of centers of their adsorption on the pore surface.

A set of catalysts from A (E) to E (T) and their intermediate forms for the content of hydrosilicazole is the basis for the formation of a protective layer of catalysts for hydrofining processes of middle distillate fractions.

Example. The reactor is loaded with a set of catalysts of 40 ml each from top to bottom: E (E) + D (E) + G (T) + B (T), under demetallization conditions at a temperature of 320 ° C and a space velocity of 1 hour ^-1 per the whole set. Within 10 hours, a hydrogenate was obtained with a content of vanadium 13 ppm, iron 8 ppm and sulfur 1320 ppm. The results show the sieve effect of a set of catalysts according to the proposed method when using it as a protective layer in the process of hydrotreating a middle distillate fraction.

Claims (4)

1. A method of producing catalysts for the demetallization of petroleum fractions by mixing aluminum hydroxide with natural materials, introducing active components, burnable additives, molding, drying and calcining, characterized in that the active components include compounds for adsorption of metal impurities and for the conversion of hetero compounds, synthetic is introduced into the mixture hydrosilicazole in an amount of 2-12% wt. in terms of A.S. (absolutely dry), as burnable additives, wood flour and / or food flour are introduced in an amount of 10-20% wt. in terms of and.with., as an activator of molding, fat solidol is introduced in the amount of 4-7% per.w. 2. The method according to p. 1, characterized in that the aluminum hydroxide preferably contains at least 50% pseudoboehmite. 3. The method according to p. 1, characterized in that the natural materials preferably contain 30-80% SiO ₂ . 4. The method according to p. 1, characterized in that the calcination of the catalyst granules is carried out at a temperature of 550-600 ° C in an atmosphere containing at least 15% oxygen for at least 10 hours.

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