RU2352394C1 - Method of activating catalyst of oil fraction hydropurification - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: catalyst is processed with sulphiding agent, which includes sulphur-organic compound and oil fraction, in particular 1.0-2.0%-solution of dimethyldisulphide in Diesel fuel, dimethyldisulphide being introduced into Diesel fuel step-by-step; thermoprocessing of catalyst being carried out as step-by-step increase of temperature within the interval 160-340°C, after which temperature is reduced to 28-290°C, with general activation duration 20-30 hours.

EFFECT: reduction of equipment corrosion with sulphur oxides, obtaining ecologically pure, low-sulphureous Diesel fuel, polycyclic aromatic hydrocarbons in small amount, increasing degree of unlimited hydrocarbons and reduction of gumming-up of main hydropurification catalyst.

3 cl, 6 ex, 1 tbl

Description

The invention relates to the field of oil refining, in particular to a method for activating catalysts for hydrotreating petroleum feedstocks.

It is known that catalysts are used in hydrogenation oil refining processes, in the production of which one or more catalytically active metals are deposited in the form of oxides (molybdenum, nickel, cobalt, tungsten). The most common applications are aluminum-cobalt-molybdenum (AKM) and aluminum-nickel-molybdenum (ASM) catalysts. It was shown that, in fact, the hydrotreatment of sulfur-containing hydrocarbons in the feed proceeds on catalysts that include active metals in the form of sulfides. Therefore, in the initial period of operation, the catalysts are activated by their sulfidation using sulfidizing agents.

It is proposed to use hydrogen sulfide as a sulfidizing agent (US Patent No. 3239451). Sulfidation of hydrotreating catalysts with gaseous hydrogen sulfide is carried out at a temperature of 200-250 ° C, a pressure of 10-150 atm, a concentration of hydrogen sulfide in the circulating gas 5-100%.

The disadvantages of this method are the danger of overheating of the catalyst as a result of exothermic sulfidation reactions and the inability to prevent and / or suppress them, the high corrosivity of gaseous hydrogen sulfide, the difficulty of obtaining and storing large quantities of concentrated gaseous hydrogen sulfide.

Known (Ch. Thomas. "Industrial catalytic processes and effective catalysts". - M., Mir, 1973, pp. 254-256) a method of activating catalysts for hydrotreating oil fractions containing metals of groups VI and VIII, by processing them with a mixture of hydrogen-containing gas with 5-10% hydrogen sulfide at a pressure of 1-35 atm, a temperature of 150-370 ° C.

The method allows to convert the oxide form of metals to sulfide, however, as a result of the high concentration of hydrogen sulfide in the gas, a significant amount of heat is released in the initial period, which leads to local overheating of the catalyst grain and, as a result, to a decrease in its activity.

Known (Europatent No. 0460300 A1, op. 11.12.91, B.I. No. 50) are methods for applying sulfur to a catalyst outside a hydrocarbon hydrotreatment reactor. For this, sulfur-containing compounds and elemental sulfur are used. It is proposed to use organosulfur compounds with a boiling point above 100 ° C for applying sulfur to the catalyst.

From Europatent No. 0460300 (A1, op. 11.12.91, B.I. No. 50) it is known that 2,2-thioethanol, thiodiglycolic acid, 3,3-thiol-dipropanol, 1,6-dihydroxy-2 can serve as an example of such compounds 5-dithihexane; 3,6-dithioheptanoic acid. The sulfur-containing compound is dissolved in water or an organic solvent, the catalyst is treated with the resulting solution, followed by drying to remove the solvent.

The disadvantages of these methods are the high cost and scarcity of individual sulfur compounds, as well as the need to remove solvent from the catalyst, which always leads to a decrease in the strength of the catalyst.

From patent No. 2140963 (RU, IPC ⁶ C10G 45/08, publ. 10.11.99.) A method for activating a catalyst package with disulfides taken in the amount of [0.2K / (K + H)] kg per 1 kg of the catalyst system is known, where K is the content of alumina-cobalt-molybdenum catalyst in the bag, kg, N is the content of alumina-nickel-molybdenum catalyst in the bag, kg, followed by the further refilling of the catalytic bag with raw materials at a temperature of 330-340 ° С. As disulfides (liquid easily decomposing organosulfur compounds) use a technical mixture of low molecular weight disulfides (sulfur content 56 wt.%).

The use of liquid easily decomposing organosulfur compounds as a sulfidizing agent makes it possible to obtain a catalytic system with high activity during the hydrofining of oil fractions. But these substances belong to the class of highly toxic and corrosive compounds.

From A.S. USSR No. 1469639 it is known to use as sulphiding agent high-sulfur distillate oil and gas condensate fractions.

However, their use does not provide a catalytic system with activity sufficient to obtain products that meet international standards.

Patent No. 2275240 (RU, IPC B01J 37/20, published April 27, 2006) describes a method for sulfidizing (activating) a hydrodesulfurization catalyst in a reaction-distillation column with sulfiding agents: H ₂ S, tertiary nonyl polysulfide (TNPS), dimethyl sulfide, and carbon disulfide. A suitable sulfidizing agent is any organic or inorganic sulfur compound that will decompose under processing conditions to convert the catalyst to sulfide.

The solvent can be selected from any streams that will boil under pressure in the reactor, preferably from jet fuel, naphtha, kerosene or diesel fuel after thorough hydrotreatment.

The column pressure is set at or above the vapor pressure of the solvent at 450 ° F, and the solvent is heated to a temperature between 400 and 450 ° F.

The disadvantage is the complex technology of the sulfidation process.

The patent No. 1820523 (RU, IPC ⁶ B01J 37/20, publ. 20.11.95.) Describes the closest (prototype) technical essence of a technical solution to a similar problem, in which the activation method of the catalyst, preferably containing 3-7 wt.% Water, carried out by processing it at elevated pressure in an atmosphere of nitrogen or hydrogen in the first stage at 20-150 ° C hydrogen sulfide, feeding to the catalyst 10-30% of the total sulfur.

Then, in the next two stages, the catalyst is treated with a sulfidizing agent, including hydrogen sulfide, elemental sulfur, organosulfur compounds, sulfur-containing oil fractions, in the second stage at 150-300 ° С, feeding 40-80% of the total amount of sulfur to the catalyst, and in the third stage with 360-390 ° C, supplying the remaining amount of sulfur.

It was shown that for the sulfidation of the catalyst, a 1% solution of dimethyl disulfide (DMDS) in diesel fuel is used only in the second and third stages, and the catalyst is moistened to a moisture content of 7 wt.%.

The residual sulfur content in the hydrogenate is 0.28 wt.%, The degree of purification of diesel fuel is 68.2%.

The disadvantages of the prototype and analogues are: a complex technological process of activation of the catalyst, the use of manual labor, uneven sulfidation of the catalyst, the possibility of excessive overheating of the catalyst and the need to strictly maintain the temperature regime throughout the volume and height of the catalyst layer, the occurrence of difficult-to-regulate temperature flashes causing catalyst deactivation due to reduction of oxides hydrogenating metals to an inactive metal state, sintering and used for sulfidization of elemental sulfur, the accumulation of water in the catalyst bed and the possibility of violating the physical integrity of the granules (cracking) and the working porous structure of the catalyst.

The objective of the present invention is to develop a method for the activation of alumina-nickel (cobalt) molybdenum catalysts for the hydroprocessing of petroleum feeds, which allows to obtain a more complete sulphurization of the catalyst, improve mechanical properties and increase its hydrodesulfurization activity in the processing of heavy types of petroleum feeds, including a large number of polycyclic aromatic hydrocarbons.

The implementation of the invention is aimed at reducing corrosion of equipment with sulfur oxides, obtaining environmentally friendly, low sulfur diesel fuel with a sulfur content of 30-250 ppm, polycyclic aromatic hydrocarbons - not more than 8.0 wt.%, To increase the degree of hydrogenation of unsaturated hydrocarbons and reduce coking of the main catalyst hydrotreating.

The elimination of these drawbacks and the achievement of the claimed technical result from the implementation of the activation method of the catalyst for hydrotreating oil fractions by treatment with a sulfidizing agent, including an organosulfur compound and oil fraction, in a hydrogen medium at elevated pressure and temperature is achieved due to the fact that the catalyst is activated in 1.0-2 , A 0% solution of dimethyl disulfide (DMDS) in light diesel fuel (fraction 160-340 ° C) at a temperature of 160-340 ° C for 20-30 hours.

Subject to sulfonation are aluminum-nickel-molybdenum (ASM) and / or aluminum-cobalt-molybdenum (AKM) catalysts, which are characterized by the following ratio of components, wt.%:

NiO and / or CoO 2.5-4.0 MoO ₃ 8.0-12.0 Na ₂ O 0.01-0.08 La ₂ o ₃ 1.5-4.0 P ₂ O ₅ 2.0-5.0 B ₂ O ₃ 0.5-3.0 Al ₂ About ₃ The rest is up to 100

In addition, the catalytic system may contain a catalyst for the protective layer (GLC), which is characterized by the following ratio of components, wt.%:

Molybdenum oxide 3.0-9.0 Nickel and / or cobalt oxide 0.5-4.0 Silica 0.8-3.0 Aluminium oxide The rest is up to 100.

Used dimethyldisulfide has the following indicators: sulfur content - 68 wt.%, Molecular weight - 94, density - 1.063 kg / dm ³ , saturated vapor pressure at 20 ° C - 2.9 KPa, the temperature of the beginning of decomposition on the catalyst - 175-205 ° FROM.

A comparative analysis of the prototype and the claimed invention shows that both methods include the activation of a catalyst for hydrotreating oil fractions by treatment with a sulfidizing agent, including an organosulfur compound and oil fraction, in a hydrogen atmosphere at elevated pressure and temperature.

A distinctive feature of the claimed invention is that the activation of the catalyst is carried out by a 1.0-2.0% solution of dimethyl disulfide (DMDS) in light diesel fuel (fraction 160-340 ° C) at a temperature of 160-340 ° C for 20-30 hours.

In this case, an organosulfur compound - dimethyldisulfide (wt.% Sulfur - 68, molecular weight - 94, density, kg / dm ³ - 1.063, saturated vapor pressure at 20 ° C, KPa - 2.9, the temperature of the beginning of decomposition on the catalyst, ° C - 175-205.

Hydrotreating of oil fractions — a mixture of straight-run diesel fuel (a fraction with boiling limits of 180-360 ° C, density 0.857 kg / m ³ and containing polycyclic aromatic hydrocarbons, as well as sulfur) and secondary gas oil on a sulfidized catalyst according to the proposed method is carried out at a temperature of 330-390 ° C, a pressure of 40-50 ati, a hydrogen-containing gas circulation of 250-400 nm ³ / m ^{3 of} raw materials, a feed space velocity of 0.8-1.3 h ^-1 .

The inventive method is as follows.

At the initial stage, the above-mentioned catalysts loaded into the reactor are dried. After drying the catalysts, the temperature in the reactor is reduced to 150 ° C at a speed of 15-20 ° C per hour while increasing the pressure at a speed of 0.4-0.5 MPa per hour to an operating value of 3.8-5.0 MPa. The circulation of the hydrogen-containing gas (WASH) set 200-250 nm ³ / m ³ raw materials.

Raw materials (light diesel fuel of fraction 160-340 ° С) are accepted for installation and the process of catalyst wetting is started. Gradually, the raw material productivity is brought up to 70-80% of the design. Then the unit is transferred to work according to the usual technological scheme, with the difference that columns designed for purification of the circulating WASH (CVSG) by monoethanolamine (MEA) are excluded from the scheme. During the process, the temperature difference across the catalyst layer does not exceed 20 ° C. The product thus obtained is withdrawn into a substandard line.

After wetting the catalyst for four hours, the consumption of raw materials and the circulation of the Wash are increased to design values and the unit is transferred to work according to the circulating scheme. Further wetting of the catalyst with a simultaneous increase in temperature at a rate of 10-15 ° C per hour is continued until the temperature in the catalyst bed reaches 160 ° C.

After the temperature is equalized at the level of 160 ° C, dimethyldisulfide (DMDS) is introduced in the amount of 1.0-2.0 wt.% On the raw material in the feedstock (light diesel fuel of the fraction 160-340 ° C) in the feedstock. To achieve complete conversion of the sulfur contained in DMDS to hydrogen sulfide, the temperature in the reactor is gradually increased to 230 ° C. In this case, the temperature at the outlet of the reactor should not exceed 240 ° C.

The sulfidation process is controlled by changing the temperature in the reactor, the gradient of which along the height of the catalyst layer should not exceed 20 ° C, and by the amount of water removed from the process.

After increasing the concentration of hydrogen sulfide at the outlet of the reactor above 0.2 vol.%, The supply of DMDS is stopped for one hour. Then, the DMDS supply is resumed, while the sulfidation of the catalyst is carried out with a stepwise rise in temperature to 340 ° C at a rate of 15 ° C per hour. At this temperature (340 ° C), the catalyst is maintained for one hour, after which the temperature is reduced to 280-290 ° C and maintained at this temperature for another two hours. After that, the supply of DMDS is stopped.

Then proceed to the conclusion of the reactor to hydrotreatment, for which they take diesel fuel (fraction 180-360 ° C). From the moment of receiving the raw materials, the MEA purification columns of the CVSG are put into operation. Work on these raw materials is carried out for 4-5 days with a gradual increase in temperature (5 ° C per day) to values that provide the required sulfur content (30-250 rpm). Such a period of work on these raw materials is necessary to stabilize the activity of the catalyst at a high level. At the end of the specified period, they switch to hydrotreating mixed raw materials (see table).

The implementation of the method allows you to convert the oxide form of the active metals contained in the catalysts, in sulfide. As a result of activation, the following sulfidated catalysts are obtained.

Aluminum-nickel-molybdenum (AMM) and / or aluminum-cobalt-molybdenum (AKM) catalysts are characterized by the following ratio of components, wt.%:

Ni ₃ S ₂ and / or Co ₃ S ₂ 2.75-4.40 MoS ₂ 8.80-13.20 Na ₂ O 0.01-0.08 La ₂ About ₃ 1,50-4,00 P ₂ O ₅ 2.00-5.00 B ₂ O ₃ 0.50-3.00 Al ₂ About ₃ The rest is up to 100

The protective layer catalyst (GLC), is characterized by the following ratio of components, wt.%:

MoS ₂ 3.3-9.9 Ni ₃ S ₂ and / or Co ₃ S ₂ 0.55-4.4 Silica 0.8-3.0 Aluminium oxide The rest is up to 100

The implementation of the invention is illustrated by the examples presented in the table. In experiments 1-3, AMN and AKM catalysts were used, which are characterized by the following ratio of components, wt.%: NiO and / or CoO — 2.5; MoO ₃ - 8.0; Na ₂ O - 0.01; La ₂ O ₃ - 1.5; P ₂ O ₅ - 2.0; In ₂ O ₃ - 0.5; Al ₂ O ₃ . the rest is up to 100. GLC is characterized by the following ratio of components, wt.%: molybdenum oxide - 3.0; nickel and / or cobalt oxide - 0.5; silicon oxide - 0.8; aluminum oxide - the rest is up to 100.

In experiments 4-6, AMN and AKM catalysts were used, which are characterized by the following ratio of components, wt.%: NiO and / or CoO - 4.0; MoO ₃ - 12.0; Na ₂ O - 0.08; La ₂ O ₃ - 4.0; P ₂ O ₅ - 5.0; In ₂ O ₃ - 3.0; Al ₂ O ₃ - the rest is up to 100. GLC is characterized by the following ratio of components, wt.%: Molybdenum oxide - 9.0; nickel and / or cobalt oxide - 4.0; silicon oxide - 3.0; aluminum oxide - the rest is up to 100.

As a result of the activation of AMN, AKM, and GLC catalysts of the indicated compositions, sulfidized forms of the catalysts are obtained, which in experiments 1–3 are characterized by the following ratio of components, wt.%: Ni ₃ S ₂ and / or Co ₃ S ₂ - 2.75; MoS ₂ - 8.8; Na ₂ O - 0.01; La ₂ O ₃ - 1.5; P ₂ O ₅ - 2.0; In ₂ O ₃ - 0.5; Al ₂ O ₃ - the rest is up to 100. GLC is characterized by the following ratio of components, wt.%: MoS ₂ - 3.1; Ni ₃ S ₂ and / or Co ₃ S ₂ - 0.55; silicon oxide - 0.8; aluminum oxide - the rest is up to 100.

In experiments 4-6, AMM and AKM catalysts were used, which are characterized by the following ratio of components, wt.%: Ni ₃ S ₂ and / or Co ₃ S ₂ - 4.4; MoS ₂ - 13.2; Na ₂ O - 0.08; La ₂ O ₃ - 4.0; P ₂ O ₅ - 5.0; In ₂ O ₃ - 3.0; Al ₂ O ₃ - the rest is up to 100. GLC is characterized by the following ratio of components, wt.%: MoS ₂ - 9.9; Ni ₃ S ₂ and / or Co ₃ S ₂ - 4.4; silicon oxide - 3.0; aluminum oxide - the rest is up to 100.

Studies have shown the possibility of activating alumina catalysts with a diesel fraction, including 1.0-2.0 wt.% Dimethyldisulfide, while achieving maximum initial catalyst activity, minimal coking in the initial period of operation and an increase in the overall sulfidation reaction cycle. The gradual (stepwise) supply of a sulfidizing agent provides a more complete sulfurization of the catalytic system while reducing the duration of the sulfidation process, a more complete absorption of hydrogen sulfide by the catalyst, thereby reducing the corrosion of technological equipment.

The implementation of the method in accordance with the claims when processing a blended feed containing polycyclic aromatic hydrocarbons results in a low-sulfur environmentally friendly diesel fuel (with a sulfur content of 30.0-250.0 ppm), with a content of polycyclic aromatic hydrocarbons of not more than 8.0 wt. %

Conditions and results of sulfidation and hydrotreating of mixed raw materials Indicators Examples one 2 3 four 5 6 Sulphidation conditions Duration of sulfidation, h twenty thirty 28 twenty thirty 28 The content of dimethyl disulfide in the diesel fraction, wt.% 1,0 1,0 1,0 2.0 2.0 2.0 Hydrotreating Conditions Temperature ° C 330 390 360 360 380 360 VSG circulation, nm ³ / m ³ raw materials 400 250 300 300 300 300 Volumetric speed, h ^-1 0.8 1.3 1,0 1,0 1,2 0.8 Content in raw materials, wt.% Secondary gas oil 10 thirty 10 10 twenty 10 Sulfur 0.3 0.7 0.3 0.4 0.7 0.5 Polycyclic aromatic hydrocarbons fourteen 16 12 12 fifteen 12 Hydrotreated Content Sulfur, ppm 250 thirty 110 130 80 one hundred Polycyclic aromatic hydrocarbons, wt. % 8.0 4.0 7.0 7.0 4.0 5,0

Claims (3)

1. A method of activating a catalyst for hydrotreating oil fractions by treating with a sulfidizing agent, including an organosulfur compound and an oil fraction, in a hydrogen medium at elevated pressure and temperature, characterized in that the catalyst is activated by a 1.0-2.0% solution of dimethyldisulfide in diesel fuel, while dimethyl disulfide is introduced into diesel fuel in stages, the heat treatment of the catalyst is also carried out in the form of a stepwise rise in temperature in the range of 160-340 ° C, after which the temperature zhayut to 280-290 ° C, with a total duration of 20-30 hours of activation. 2. The method of activating a catalyst for hydrotreating oil fractions according to claim 1, characterized in that dimethyldisulfide containing 68 wt.% Sulfur, having a molecular weight of 94, a density of 1.063 kg / dm ³ , a saturated vapor pressure at 20 ° C, is used, 2 , 9 KPa, the temperature of the onset of decomposition on the catalyst is 175-205 ° C. 3. The method of activating a catalyst for hydrotreating oil fractions according to claim 1, characterized in that lightweight diesel fuel is used with boiling limits of 160-340 ° C.