A silicon capture catalyst and its preparation method and application

Abstract

The present invention provides a silicon-capturing catalyst comprising alumina, pseudo-boehmite, and an active component. The active components are Group VIB metal sulfide and Group VIII metal sulfide, which are supported on an alumina carrier. The pseudo-boehmite is in-situ directionally grown on the outer surface of the silicon-capturing catalyst. The pseudo-boehmite has a velvet-worm-like particle morphology and a primary particle size of 5-15 nm. The catalyst is first sulfurized after loading the active metal and then placed in an aqueous propylene oxide solution for sealed heat treatment. The pseudo-boehmite component on the outer surface of the silicon-capturing catalyst provides abundant surface hydroxyl groups for the silicon-capturing agent, thereby greatly improving its silicon-holding capacity.

Description

Technical Field

[0001] The invention belongs to the field of petroleum refining, and in particular relates to a silicon-capturing catalyst, a preparation method thereof, and a method for hydrogenating and capturing silicon using the same. Background Art

[0002] At present, my country still has a large number of delayed coking units that process heavy and low-quality oils. Defoamers are used in the process, which results in a certain amount of silicon in products such as coking dry gas, coking naphtha, and coking diesel. Silicon poisons the catalysts used in the subsequent treatment of coking products, leading to permanent deactivation of the catalysts. Therefore, the hydroprocessing processes of coking dry gas, coking naphtha, and coking diesel require the installation of silicon-capturing catalysts. At the same time, the silicon-capturing catalysts must not only have strong silicon-capturing capabilities but also have certain hydrogenation activity. Studies have found that the silicon type in coking products is mainly cyclosiloxane compounds. In order to capture silicon on the silicon-capturing catalyst, the silicon-oxygen ring of the cyclosiloxane must be opened, which requires the silicon-capturing catalyst to have a high acidity.

[0003] CN201911020761.2 discloses a silicon scavenger and a preparation method thereof. The silicon scavenger of the present invention comprises a carrier and a hydrogenation active component, wherein the hydrogenation active component is a Group VIB metal sulfide, a Group VIB metal oxide, and a Group VIII metal oxide. Based on the total weight of the silicon scavenger, the Group VIB metal sulfide is 0.3wt%-18.3wt%, the Group VIB metal oxide is 0.1wt%-5.0wt%, and the Group VIII metal oxide is 0.2wt%-12.0wt%. The preparation method of the silicon scavenger of the present invention comprises the following steps: (1) impregnating a catalyst carrier with an impregnation solution containing a Group VIB metal, then drying the catalyst carrier, and then subjecting the dried catalyst carrier to a sulfurization treatment; (2) impregnating the catalyst carrier with an impregnation solution containing Group VIB and Group VIII metals into the catalyst carrier after sulfurization in step (1), and then drying and calcining the catalyst carrier under an inert atmosphere to obtain the silicon scavenger. The active component of the silicon scavenger of the present invention has a high degree of sulfidation, and the silicon scavenger has a high silicon holding capacity, and is suitable for desiliconization and silicon capture of silicon-containing oil products such as coking dry gas, coking naphtha, and coking diesel.

[0004] CN200710012085.5 A method for hydrorefining silicon-containing distillate oil, wherein silicon-containing distillate oil raw material and hydrogen are passed through at least two hydrorefining catalyst beds under hydrorefining conditions, wherein the silicon-containing distillate oil raw material first passes through a hydrorefining catalyst bed with a silicon-trapping function and then passes through a conventional hydrorefining catalyst bed; wherein the hydrorefining catalyst with a silicon-trapping function has a larger pore volume and specific surface area and a relatively low metal content.

[0005] The silicon-capturing catalyst of the above-mentioned invention patent is prepared by impregnating active metal into alumina or modified alumina carrier. Although alumina or modified alumina carrier has a large specific surface area, high-temperature calcination of alumina or modified alumina carrier will cause a loss of specific surface area, thereby reducing the silicon-holding capacity of the silicon-capturing catalyst. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a silicon-capturing catalyst and a preparation method thereof. The catalyst not only has high hydrodesulfurization, hydrodenitrogenation, and olefin saturation activities, but also has a high silicon-holding capacity, which can effectively capture silicon in the feedstock oil and prevent the main catalyst from being poisoned and deactivated by silicon.

[0007] In the context of this specification, FTIR (infrared spectroscopy) was used to analyze the surface hydroxyl content of the catalyst. The FTIR test conditions included: the catalyst was ground, pressed into a Φ13 mm self-supporting sheet, and placed on the in-situ cell sample holder; the experiment was performed using a Nicolet 6700 Fourier transform infrared spectrometer with 32 scans and a resolution of 4 cm -1 , 4000~650cm -1 All infrared experimental results were normalized according to the catalyst mass, and the hydroxyl content was normalized using the molar integral absorption coefficient Ao = 1.5 cm / μmol and 3590-3830 cm -1 The specific surface area of ​​the silicon trap was analyzed by N2 adsorption / desorption. The N2 adsorption / desorption test conditions were as follows: the catalyst was loaded into a sample tube and N2 adsorption and desorption tests were performed at 77K using an ASAP 2420 nitrogen physical adsorption instrument from MICROMERITICS, USA. The microstructure of the catalyst was characterized by scanning electron microscopy. The specific operation was as follows: the microstructure of the support was characterized by a JSM-7500F scanning electron microscope with an accelerating voltage of 5 kV, an accelerating current of 20 μA, and a working distance of 8 mm.

[0008] The technical purpose of the first aspect of the present invention is to provide a silicon-capturing catalyst, comprising alumina, pseudo-boehmite and an active component, wherein the active component is a Group VIB metal sulfide and a Group VIII metal sulfide, and the Group VIB metal sulfide and the Group VIII metal sulfide are loaded on an alumina carrier and pseudo-boehmite. The pseudo-boehmite is in-situ directionally grown on the outer surface of the silicon-capturing catalyst, and the particle morphology of the pseudo-boehmite is a velvet-worm-like structure, and the velvet-worm-like particle size is 80-350 nm.

[0009] Furthermore, the surface hydroxyl content of the silicon capture catalyst is 1000-2000 μmol / g, preferably 1200-1800 μmol / g.

[0010] Furthermore, based on the total weight of the catalyst, the Group VIB metal sulfide is 2-20%, preferably 3-13%, and the Group VIII metal sulfide is 1-10%, preferably 2-5%;

[0011] Furthermore, the Group VIB metal sulfide is molybdenum sulfide and / or tungsten sulfide, and the Group VIII metal sulfide is nickel sulfide and / or cobalt sulfide.

[0012] The technical purpose of the second aspect of the present invention is to provide a method for preparing the above-mentioned silicon capture catalyst, comprising the following steps:

[0013] (1) introducing a Group VIB metal salt and a Group VIII metal salt into an alumina support by an impregnation method, and sulfiding to obtain a catalyst precursor;

[0014] (2) Immersing the catalyst precursor of step (1) in a propylene oxide aqueous solution for sealed heat treatment, separating the material after treatment into solid and liquid, and drying the solid phase material to obtain the silicon capture catalyst.

[0015] Furthermore, the Group VIB metal salt in step (1) is a phosphate and / or an ammonium salt.

[0016] Furthermore, the Group VIII metal salt in step (1) is selected from one or more of nitrates, carbonates, phosphates, sulfates, basic carbonates and acetates.

[0017] Furthermore, the necessary drying and calcining processes may be included before vulcanization in step (1), wherein the drying conditions are: drying temperature 90-300° C., drying time 3-6 hours; and the calcining conditions are: calcining temperature 300-600° C., drying time 3-6 hours.

[0018] Furthermore, the vulcanization treatment in step (1) is dry vulcanization or wet vulcanization. The vulcanizing agent for dry vulcanization is hydrogen sulfide, and the vulcanizing agent for wet vulcanization is one or two selected from carbon disulfide, dimethyl disulfide, methyl sulfide, and n-butyl sulfide; the vulcanization pressure is 2.0-6.4 MPa, the vulcanization temperature is 250-400° C., and the vulcanization time is 4-12 hours.

[0019] Furthermore, the mass percentage concentration of the propylene oxide aqueous solution in step (2) is 2.5%-12%, preferably 4%-8%, and the mass ratio of the propylene oxide aqueous solution to the catalyst precursor is 3:1-10:1, preferably 4:1-8:1.

[0020] Furthermore, the sealed heat treatment in step (2) is carried out in a sealed container, which is preferably an autoclave, and the sealed heat treatment is a two-step sealed heat treatment, i.e., first sealed heat treatment at 60-100°C for 1-4 hours, and then at 110-180°C, preferably 120-160°C, for 2-6 hours, preferably 2-4 hours.

[0021] In the method of the present invention, the drying temperature in step (2) is 100-160° C., and the drying time is 2-8 hours.

[0022] A third aspect of the present invention provides a method for desiliconizing an oil product, wherein the oil product is contacted with the above-mentioned silicon-capturing catalyst for reaction.

[0023] Furthermore, the oil product desiliconization is carried out in a fixed-bed reactor, where the above-mentioned silicon-capturing catalyst is loaded into the reactor to form a catalyst bed, which then reacts with the oil product. The reaction conditions are as follows: reaction temperature of 260-350°C, pressure of 2.0-8.0 MPa, and hydrogen-to-oil ratio of 100:1-1000:1.

[0024] In the method of the present invention, the oil product is generally one or more silicon-containing oil products such as coking dry gas, coking naphtha, coking diesel, etc., with a silicon content of 1-2000ppm.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The outer surface of the silicon-capturing catalyst of the present invention is a pseudo-boehmite component, which provides abundant surface hydroxyl groups for the silicon-capturing catalyst, thereby greatly improving its silicon-holding capacity.

[0027] (2) The present invention obtains a catalyst having pseudo-boehmite directionally grown on the carrier surface by placing a catalyst precursor in a propane solution and subjecting it to a sealed heat treatment. During the low-temperature sealed heat treatment, propylene oxide is hydrolyzed to form an alcohol solution, and the solution is made weakly alkaline. During the high-temperature sealed hydrothermal treatment, the surface grains of the alumina carrier grow outward in situ in an alkaline and alcohol solution environment to form velvet-worm-like pseudo-boehmite particles. The surface of the pseudo-boehmite generated in situ also has active metal sulfides. At the same time, the pseudo-boehmite primary grains also grow on the originally loaded active metal sulfide wafers. The generated pseudo-boehmite can provide abundant surface hydroxyl groups, thereby improving the silicon-capturing capacity of the silicon-trapping catalyst.

[0028] (3) In the silicon capture catalyst of the present invention, the Group VIB metal sulfide and the Group VIII metal sulfide are loaded on an alumina carrier, and the pseudo-boehmite is in situ grown on the surface of the alumina and / or the active component, which can increase the contact area between the pseudo-boehmite and the Group VIII metal and the Group VIB metal, improve the synergistic effect between the hydrogenation performance and the silicon capture performance of the silicon capture catalyst, improve the silicon holding capacity of the silicon capture catalyst, and at the same time reduce the carbon deposition of the catalyst to prevent carbon deposition from occupying the silicon capture active sites.

[0029] (4) The silicon-capturing catalyst of the present invention is in a sulfurized state and does not require sulfurization treatment during use, thereby preventing temperature fluctuations during the sulfurization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the SEM spectrum of the silicon-trapping catalyst of Example 1. DETAILED DESCRIPTION

[0031] The technical solutions and effects of the present invention are further described below with reference to the following examples, but are not limited to the following examples. In the present invention, wt% represents mass fraction.

[0032] Example 1

[0033] (1) An impregnation solution containing ammonium heptamolybdate and nickel nitrate was impregnated into an alumina support in equal volumes. After impregnation, the solution was dried at 110°C for 3 hours and calcined at 400°C for 3 hours. The solution was then sulfided with hydrogen containing 1.5% H2S at a temperature of 330°C, a pressure of 3.2 MPa, and a time of 5 hours. The solution was then cooled to room temperature in a N2 atmosphere to obtain a catalyst precursor.

[0034] (2) Weigh 100 g of the catalyst precursor, add 550 g of a 6.2% propylene oxide aqueous solution, transfer the mixture into an autoclave, seal the autoclave, place it in an oven and seal it at 70°C for 2.8 hours, then heat it to 135°C and seal it for 3 hours. After treatment, the material is cooled, washed, and filtered, and the solid material is dried at 120°C for 3 hours to obtain a silicon capture catalyst Cat-1. The SEM image of Cat-1 is shown in FIG. Figure 1 , properties are shown in Table 1.

[0035] The weight percentages of the components in the silicon capture catalyst Cat-1 are: MoS2 is 9.3%, and NiS is 4.6%.

[0036] Example 2

[0037] (1) An impregnation solution containing ammonium heptamolybdate and cobalt nitrate was impregnated into an alumina support in equal volumes. After impregnation, the solution was dried at 120°C for 5 hours and calcined at 450°C for 4 hours. The solution was then sulfided with hydrogen containing 1.5% H2S at a temperature of 340°C, a pressure of 3.6 MPa, and a time of 5 hours. The solution was then cooled to room temperature in a N2 atmosphere to obtain a catalyst precursor.

[0038] Step (2) is the same as Example 1, except that the concentration of propylene oxide in step (2) is 5.5%, the amount of solution used is 630 g, and the hydrothermal treatment is first performed at 80° C. for 2.5 hours and then at 145° C. for 2.5 hours to obtain silicon capture catalyst Cat-2. The properties are shown in Table 1.

[0039] The weight percentages of the components in the silicon capture catalyst Cat-2 are: MoS2 is 9.6%, and NiS is 3.1%.

[0040] Example 3

[0041] (1) An impregnation solution containing ammonium heptamolybdate, nickel nitrate and cobalt nitrate was impregnated into an alumina support in equal volumes. After impregnation, the solution was dried at 120°C for 4 hours and calcined at 500°C for 3 hours. The solution was then sulfided with hydrogen containing 1.5% H2S at a temperature of 360°C, a pressure of 4.2 MPa and a time of 6 hours. The solution was then cooled to room temperature in a N2 atmosphere to obtain a catalyst precursor.

[0042] Step (2) is the same as Example 1, except that the concentration of propylene oxide in step (2) is 4.5%, the amount of solution used is 720 g, and the hydrothermal treatment is first performed at 60° C. for 3.5 hours and then at 160° C. for 2 hours to obtain silicon capture catalyst Cat-3. The properties are shown in Table 1.

[0043] The weight percentages of the components in the silicon capture catalyst Cat-3 are: MoS2 is 10.6%, NiS is 2.7%, and CoS is 1.1%.

[0044] Example 4

[0045] (1) An impregnation solution containing ammonium metatungstate and nickel nitrate was impregnated into an alumina support in equal volumes. After impregnation, the solution was dried at 120°C for 4 hours and calcined at 500°C for 3 hours. The solution was then sulfided with hydrogen containing 2.5% H2S at a temperature of 360°C, a pressure of 4.2 MPa, and a time of 4 hours. The solution was then cooled to room temperature in a N2 atmosphere to obtain a catalyst precursor.

[0046] Step (2) is the same as Example 1, except that the concentration of propylene oxide in step (2) is 7.6%, the amount of solution used is 430 g, and the hydrothermal treatment is first performed at 90° C. for 1.5 hours and then at 120° C. for 3 hours to obtain silicon capture catalyst Cat-4. The properties are shown in Table 1.

[0047] The weight percentages of the components in the silicon capture catalyst Cat-4 are: WS2 is 11.5%, and NiS is 3.6%.

[0048] Comparative Example 1

[0049] The same method as Example 1 was used, except that the propylene oxide aqueous solution was replaced with an ammonia aqueous solution of the same mass concentration to prepare a comparative silicon trap DC-1. The properties are shown in Table 1.

[0050] Comparative Example 2

[0051] The same method as Example 1 was used, except that the propylene oxide aqueous solution was replaced with an ethylene oxide solution of the same concentration to prepare a comparative silicon trap DC-2. The properties of the DC-2 are shown in Table 1.

[0052] Comparative Example 3

[0053] The same method as Example 1 was used, except that the propylene oxide concentration was 1%. A comparative silicon trapping agent DC-3 was prepared, and its properties are shown in Table 1.

[0054] Comparative Example 4

[0055] The same as Example 1, except that the hydrothermal treatment is a one-step hydrothermal treatment, the heat treatment temperature is 60° C., and the treatment time is 20 hours, to prepare a comparative silicon scavenger DC-4, the properties of which are shown in Table 1.

[0056] Comparative Example 5

[0057] The same method as in Example 1 was used, but without the treatment process of step (2), to prepare a comparative silicon trapping agent DC-5, the properties of which are shown in Table 1.

[0058] Table 1

[0059]

[0060] It can be seen from the data in Table 1 that, compared with the silicon scavenger of the comparative example, the silicon scavenger prepared by the method of the present invention has a higher specific surface area and hydroxyl content.

[0061] Example 5

[0062] The silicon capture catalysts Cat-1, Cat-2, Cat-3, Cat-4 of the present invention and the silicon capture agents DC-1, DC-2, DC-3, DC-4, DC-5 prepared in the comparative example were respectively loaded into a fixed bed hydrogenation reactor to examine their silicon capture activity. The evaluation raw oil used was coking naphtha raw material provided by a refinery of Sinopec, and its main properties are as follows: silicon content of 134μg / g, sulfur content of 2123μg / g, and nitrogen content of 56μg / g. The evaluation reaction conditions are: operating pressure of 4.0MPa, reaction temperature of 310℃, hydrogen / oil volume ratio of 500:1, volume space velocity of 5.0h -1 After running for 20 hours, the desulfurization and denitrification rates of the silicon scavenger were tested. After running for 300 hours, the silicon scavenger was unloaded and then calcined at 500℃ in a nitrogen atmosphere for 3 hours. The SiO2 content in the silicon scavenger was analyzed by XRF. The evaluation results are shown in Table 2.

[0063] Table 2.

[0064] Catalyst No. <![CDATA[Silica content (calculated as SiO2), %]]> Desulfurization rate, % Denitrification rate, % Cat-1 20.2 75 79 Cat-2 33.1 78 82 Cat-3 35.2 80 87 Cat-4 29.3 89 93 DC-1 8.1 65 69 DC-2 7.9 79 77 DC-3 10.8 76 78 DC-4 12.8 80 79 DC-5 5.2 85 81

[0065] As can be seen from Table 2, the silicon-capturing catalyst of the present invention has a very high silicon-holding capacity.

Claims

1. A silicon capture catalyst, characterized in that The catalyst comprises alumina, pseudo-boehmite, and active components. The active components are Group VIB metal sulfide and Group VIII metal sulfide. The Group VIB metal sulfide and Group VIII metal sulfide are supported on an alumina carrier and pseudo-boehmite. The pseudo-boehmite is in-situ directionally grown on the outer surface of the silicon capture catalyst. The pseudo-boehmite particles have a velvet-worm-like structure and a velvet-worm-like particle size of 80-350 nm. Based on the total weight of the catalyst, the Group VIB metal sulfide accounts for 2-20% and the Group VIII metal sulfide accounts for 1-10%. The surface hydroxyl content of the silicon capture catalyst is 1000-2000 μmol / g. The silicon capture catalyst is prepared by the following steps: (1) Introducing Group VIB metal salts and Group VIII metal salts into an alumina support by impregnation, followed by sulfidation, to obtain a catalyst precursor; prior to sulfidation, necessary drying and calcination processes are also required, with the drying temperature being 120-300°C; (2) The catalyst precursor of step (1) is immersed in an aqueous solution of propylene oxide and subjected to sealed heat treatment. After the treatment, the material is subjected to solid-liquid separation, and the solid phase material is dried to obtain the silicon capture catalyst; wherein the mass percentage concentration of the aqueous solution of propylene oxide is 2.5%-12%; the sealed heat treatment is a two-step sealed heat treatment, first, sealed heat treatment at 60-100°C for 1-4 hours, and then at 110-180°C for 2-6 hours.

2. The silicon-trapping catalyst according to claim 1, characterized in that The surface hydroxyl content of the silicon capture catalyst is 1200-1800 μmol / g.

3. The silicon-trapping catalyst according to claim 1, characterized in that The Group VIB metal sulfide is molybdenum sulfide and / or tungsten sulfide, and the Group VIII metal sulfide is nickel sulfide and / or cobalt sulfide.

4. The method for preparing the silicon-trapping catalyst according to any one of claims 1 to 3, comprising the following steps: (1) Introducing Group VIB metal salts and Group VIII metal salts into an alumina support by impregnation, followed by sulfidation, to obtain a catalyst precursor; prior to sulfidation, necessary drying and calcination processes are also required, with the drying temperature being 120-300°C; (2) The catalyst precursor of step (1) is immersed in an aqueous solution of propylene oxide and subjected to sealed heat treatment. After the treatment, the material is subjected to solid-liquid separation, and the solid phase material is dried to obtain the silicon capture catalyst, wherein the mass percentage concentration of the aqueous solution of propylene oxide is 2.5%-12%; the sealed heat treatment is a two-step sealed heat treatment, first, sealed heat treatment at 60-100°C for 1-4 hours, and then at 110-180°C for 2-6 hours.

5. The preparation method according to claim 4, characterized in that The Group VIB metal salt described in step (1) is a phosphate and / or an ammonium salt; the Group VIII metal salt is selected from one or more of nitrates, carbonates, phosphates, sulfates, basic carbonates and acetates.

6. The preparation method according to claim 4, characterized in that The drying time in step (1) is 3-6 hours; the roasting conditions are: roasting temperature 300-600°C, time 3-6 hours.

7. The preparation method according to claim 4, characterized in that The vulcanization treatment in step (1) is dry vulcanization or wet vulcanization. The vulcanizing agent for dry vulcanization is hydrogen sulfide, and the vulcanizing agent for wet vulcanization is selected from one or two of carbon disulfide, dimethyl disulfide, methyl sulfide and n-butyl sulfide; the vulcanization pressure is 2.0-6.4 MPa, the vulcanization temperature is 250-400°C, and the vulcanization time is 4-12 h.

8. The preparation method according to claim 4, characterized in that The mass ratio of the propylene oxide aqueous solution used in step (2) to the alumina carrier is 3:1-10:

1.

9. The preparation method according to claim 4, characterized in that The second step is sealing heat treatment at 120-160°C for 2-4 hours.

10. The preparation method according to claim 4, characterized in that The drying temperature in step (2) is 100-160° C., and the drying time is 2-8 hours.

11. A method for desiliconizing an oil product, comprising contacting the oil product with the silicon-trapping catalyst according to claim 1 for reaction.

12. The method according to claim 11, characterized in that The oil product desiliconization is carried out in a fixed bed reactor, and a silicon-capturing catalyst is loaded into the reactor to form a catalyst bed, which contacts and reacts with the oil product. The reaction conditions are as follows: reaction temperature of 260-350°C, pressure of 2.0-8.0MPa, and hydrogen-to-oil ratio of 100:1-1000:1.

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