A method for removing silicon from oil

Abstract

The application discloses a method for removing silicon from oil products, which comprises the following steps: contacting a silicon capturing agent with oil products; and reacting. The silicon capturing agent comprises an alumina carrier and sheet-like pseudo-boehmite grown in situ on the surface of the alumina carrier. The alumina carrier is a spherical particle aggregate, and the alumina carrier contains micron-level spherical cavities. The sheet-like pseudo-boehmite is grown in situ on the outer surface of the alumina carrier and in the micron-level spherical cavities. The surface hydroxyl content of the silicon capturing agent is 1000-2000 µmol / g, and preferably 1200-1800 µmol / g. The silicon capturing agent in the method has a suitable space structure, high surface and internal hydroxyl content, and can play a high silicon-containing capacity in the silicon removal of oil products, and has a wide application prospect in the silicon removal of coking oil products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of petroleum refining, and particularly relates to a method for removing silicon from oil products. BACKGROUND

[0002] At present, a large number of delayed coking devices are still used to treat heavy and poor quality oil in China, and defoaming agents are used in the treatment process, resulting in a certain amount of silicon in the products such as coking dry gas, coking naphtha, coking diesel oil, etc. Silicon causes poisoning of the catalysts for subsequent treatment of the coking products, resulting in permanent deactivation of the catalysts. Therefore, the hydrogenation treatment process of coking dry gas, coking naphtha, coking diesel oil, etc. needs to be loaded with a silicon capture catalyst.

[0003] CN200910188090.0 discloses a coking naphtha silicon capture agent and its application. The coking naphtha silicon capture agent uses alumina as a carrier, silicon dioxide as an additive, and W, Mo and Ni as hydrogenation components. The pore volume of the coking naphtha silicon capture agent is 0.5-0.70 mL / g, the specific surface area is 250-500 m 2 / g, the hydrogenation component content is 1%-20% in terms of oxides, and the acid content is 0.3-0.5 mmol / g.

[0004] CN201911020775.4 discloses an oil product silicon capture agent and a preparation method thereof. The oil product silicon capture agent includes a carrier and a hydrogenation active component. The hydrogenation active component is a Group VIII metal sulfide, a Group VIB metal oxide and a Group VIII metal oxide. The Group VIII metal sulfide is 0.1wt%-12.2wt%, the Group VIB metal oxide is 0.5wt%-17.2wt%, the Group VIII metal oxide is 0.1wt%-9.0wt%, and the carrier is 61.6%-90.3% based on the total weight of the silicon capture agent. The preparation method includes the following contents: (1) impregnating the silicon capture agent carrier with an impregnation liquid containing a Group VIII metal, then drying the material, and then performing sulfidation treatment on the dried material; (2) impregnating the material after sulfidation in step (1) with an impregnation liquid containing a Group VIB metal and a Group VIII metal, and then performing drying and calcination under an inert atmosphere to obtain the oil product silicon capture agent.

[0005] The above-mentioned silicon capture catalyst is prepared by impregnating active metals into an alumina or modified alumina carrier. Although the alumina or modified alumina carrier has a large specific surface area, high-temperature calcination of the alumina or modified alumina carrier will cause loss of the specific surface area and change the surface properties of the carrier, reducing the silicon capturing capacity of the silicon capture catalyst. SUMMARY

[0006] In view of the deficiencies in the prior art, the oil desilication method provided by the present application adopts a silicon capturing agent with a suitable spatial structure and a high content of surface and internal hydroxyl groups, which can exhibit a high silicon capacity in oil desilication and has a broad application prospect in the removal of silicon from coking oil.

[0007] The oil desilication method of the present application adopts a silicon capturing agent to contact and react with oil; the silicon capturing agent comprises an alumina carrier and flaky pseudo-boehmite grown in situ on the surface of the alumina carrier; the alumina carrier is a spherical particle aggregate, and the alumina carrier contains micron-level spherical cavities inside; the flaky pseudo-boehmite is grown in situ on the outer surface of the alumina carrier and in the micron-level spherical cavities. The surface hydroxyl content of the silicon capturing agent is 1000-2000 µmol / g, preferably 1200-1800 µmol / g.

[0008] In the method of the present application, the particle size of the flaky pseudo-boehmite is 100-600 nm; the micron-level spherical cavity filling rate is 40%-80%, wherein the filling rate refers to the percentage of the volume of the flaky pseudo-boehmite particles in the micron-level spherical cavities to the volume of the micron-level spherical cavities.

[0009] In the method of the present application, the outer surface coverage of the alumina carrier is 85%-100%, wherein the coverage refers to the percentage of the flaky pseudo-boehmite particles on the outer surface of the alumina carrier to the outer surface of the alumina carrier.

[0010] In the method of the present application, the grain size of the spherical particles is 80-200 nm.

[0011] In the method of the present application, the preparation method of the silicon capturing agent comprises the following contents:

[0012] (1) preparing an alumina carrier precursor containing micron-level spherical cavities;

[0013] (2) immersing the alumina carrier precursor obtained in step (1) into an epoxy propane aqueous solution for sealed heat treatment, and after the treatment, the material is subjected to solid-liquid separation, and the solid material is dried to obtain the silicon capturing agent.

[0014] In step (1), the alumina carrier precursor containing micron-level spherical cavities is γ-phase alumina; its shape can be the shape of a conventional alumina carrier, such as a spherical shape, and its particle size is generally 2-8.0 mm; its shape can also be a cylindrical strip, a three-leaf clover, a four-leaf clover, etc., and its diameter is about 0.2-3.0 mm and its length is about 3-8.0 mm. The micron-level spherical cavities have a diameter of 1-10 microns, and the content of the micron-level spherical cavities can be controlled as needed, preferably the pore volume of the micron-level spherical cavities accounts for 1%-30% of the total pore volume of the alumina carrier precursor, more preferably 5%-20%.

[0015] The alumina carrier precursor containing microspherical cavities in step (1) can be prepared by the following method: mixing microspherical activated carbon and pseudoboehmite, adding deionized water to the mixture and stirring, drying the mixture, and then kneading, drying, and calcining the dried mixture to obtain the alumina carrier precursor. The microspherical activated carbon can be prepared by existing methods or purchased. The diameter of the microspherical activated carbon is 1-10 microns. The mass ratio of the microspherical activated carbon to the pseudoboehmite is 1:4-1:9. The amount of deionized water added is such that the mass ratio of liquid to solid in the slurry is 5:1-10:1. The stirring can be completed by magnetic stirring or mechanical stirring. The stirring time is 1-4 hours. The kneading and molding are performed by conventional methods in the art. During the molding process, a lubricant and a peptizing agent can be added as needed. The lubricant is pearl millet powder, and the amount added is 0.1wt%-0.5wt% of the weight of the alumina carrier. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and oxalic acid. The amount of the peptizing agent added is 0.5wt%-1.5wt% of the weight of the alumina carrier. The drying temperature is 100-160℃, and the drying time is 6-10 hours. The calcination temperature is 450-700℃, and the calcination time is 4-6 hours. The calcination is performed in an oxygen-containing atmosphere.

[0016] The mass percentage concentration of the propylene oxide aqueous solution in step (2) is 2.5%-12%, preferably 4%-8%. The mass ratio of the amount of the propylene oxide aqueous solution to the alumina carrier precursor is 3:1-10:1, preferably 4:1-8:1.

[0017] The sealing heat treatment in step (2) is performed in a sealed container, preferably an autoclave. The sealing heat treatment is first performed at 60-100℃ for 1-4 hours, and then at 110-180℃, preferably 120-160℃, for 14-20 hours.

[0018] The drying temperature in step (2) is 100-160℃, and the drying time is 2-8 hours.

[0019] In the method, the oil product desiliconization is performed in a fixed bed reactor, the silicon capturing agent is loaded into the reactor to form a catalyst bed, and the oil product is contacted and reacted. The reaction conditions are as follows: the reaction temperature is 180-320℃, the pressure is 2.0-8.0 MPa, and the hydrogen / oil ratio is 100:1-1000:1.

[0020] In the method, the oil product is generally one or more of coking dry gas, coking naphtha, and coking diesel oil containing silicon, and the silicon content is 1-2000 ppm.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] (1) The silicon capturing agent used in the oil desilication method of the present application is alumina coated with pseudoboehmite on the surface and in the micrometer-sized spherical cavities. The pseudoboehmite on the surface and in the spherical cavities endows the silicon capturing agent with a high content of surface hydroxyl groups, thereby making it have a strong ability to capture and contain silicon, a high silicon removal capacity in oil desilication, and a long service life.

[0023] (2) The silicon capturing agent used in the method of the present application is first prepared by preparing an alumina carrier precursor containing micrometer-sized pores, and then the alumina carrier precursor is immersed in a propylene oxide solution and subjected to a sealed hydrothermal treatment. Under the special hydrothermal environment, the surface of the alumina carrier with growth space in situ grows to form sheet-like pseudoboehmite. The sheet-like pseudoboehmite on the surface and in the micrometer-sized cavities has a high coverage and filling rate, which is conducive to improving the silicon containing capacity of the silicon capturing agent. The silicon-containing compounds in the raw oil that need to be desilicated first react with the hydroxyl groups of the pseudoboehmite on the outer surface to perform the first desilication. The sheet-like structure in the silicon capturing agent can well intercept the silicon in the raw material for multiple times of reaction, and the small amount of unreacted silicon-containing compounds diffuse to the pseudoboehmite in the spherical cavities to continue the reaction for secondary desilication, thereby greatly improving the silicon containing capacity of the silicon capturing agent.

[0024] In the context of the present specification, the hydroxyl content of the catalyst is analyzed by FTIR (infrared spectroscopy). The test conditions of the FTIR include: the catalyst is ground and pressed into a self-supporting sheet with a diameter of 13 mm and placed on an in-situ cell sample holder. The experiment uses a Nicolet 6700 Fourier transform infrared spectrometer, the scanning number is 32 times, the resolution is 4 cm -1 , the measurement range is 4000~650 cm -1 , and the detector is MCT / A. All infrared experimental results are normalized according to the mass of the catalyst, and the hydroxyl content is calculated using the molar integral absorption coefficient Ao=1.5 cm / μmol and the integral intensity of 3590-3830 cm -1 . The specific surface area of the silicon capturing agent is analyzed by N2-adsorption / desorption. The N2-adsorption / desorption test conditions are as follows: the catalyst is loaded into a sample tube, and an ASAP 2420 nitrogen physical adsorption instrument of the American MICROMERITICS company is used to perform N2 adsorption and desorption tests at a temperature of 77 K. The microstructure of the silicon capturing agent is characterized by scanning electron microscopy. The specific operation is as follows: the microstructure of the silicon capturing agent is characterized by a JSM-7500F scanning electron microscope at an acceleration voltage of 5 KV, an acceleration current of 20µA, and a working distance of 8 mm. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM image of the surface of the silicon capturing agent Cat-1 prepared in Example 1.

[0026] Figure 2 is a cross-sectional SEM image of the silicon capturing agent Cat-1 prepared in Example 1. DETAILED DESCRIPTION

[0027] The technical solutions and technical effects of the present application are further illustrated below in combination with examples, but are not limited to the following examples. In the present application, wt% represents mass fraction.

[0028] Preparation of microspherical activated carbon:

[0029] The microspherical activated carbon used in the method of the present application is prepared according to the method in the literature: Hydrothermal Carbonization-CO2 Activation of Carboxymethyl Cellulose for Preparing Microspherical Activated Carbon. [J]. Wood Chemistry and Technology, 2015, 35(4): 21-27. The diameter of the prepared microspherical activated carbon is 1-10 microns. Example 1

[0030] (1) Preparation of alumina carrier precursor

[0031] 100 grams of the above microspherical activated carbon, 600 grams of pseudoboehmite, and deionized water were weighed and mixed uniformly. The liquid-solid mass ratio in the mixture was 8:1. The mixture was mechanically stirred for 2 hours. After stirring, the mixture was subjected to liquid-solid separation, and the solid material was dried at 130°C for 6 hours. 4.5 grams of sesbania powder was added to the dried material and mixed uniformly. Then, an appropriate amount of 0.5% acetic acid solution was added to the mixture and kneaded uniformly. The formed material was dried at 130°C for 8 hours and calcined at 600°C in an oxygen atmosphere for 5 hours to obtain an alumina carrier precursor S0. The properties of the alumina carrier precursor are shown in Table 1.

[0032] (2) Preparation of silicon capturing agent

[0033] 100 grams of the alumina carrier precursor of step (1) and 650 grams of a 5.2% propylene oxide aqueous solution were weighed and mixed. The mixture was transferred into an autoclave, which was then sealed and placed in an oven. The sealed autoclave was first treated at 85°C for 2 hours and then treated at 150°C for 17 hours. After cooling, the material was washed, filtered, and the solid material was dried at 120°C for 6 hours to obtain a silicon capturing agent Cat-1. The properties of Cat-1 are shown in Table 1. The outer surface scanning electron microscope image of Cat-1 is shown in Figure 1 , and the cross-sectional scanning electron microscope image is shown in Figure 2 . Example 2

[0034] The same as example 1, except that the amount of pseudo-boehmite added in step (1) is 700 g, and the liquid-solid mass ratio during stirring is 7:1. In step (2), the concentration of propylene oxide is 6.5%, and the amount of solution used is 520 g. During hydrothermal treatment, first, the solution is treated at 75°C for 2.5 hours, then the temperature is raised to 140°C, and the treatment time is 18 hours, to obtain the silicon capturing agent Cat-2, the properties of which are shown in Table 1. Example 3

[0035] The same as example 1, except that the amount of pseudo-boehmite added in step (1) is 500 g, and the liquid-solid mass ratio during stirring is 6:1. In step (2), the concentration of propylene oxide is 4.6%, and the amount of solution used is 740 g. During hydrothermal treatment, first, the solution is treated at 95°C for 1.5 hours, then the temperature is raised to 160°C, and the treatment time is 16 hours, to obtain the silicon capturing agent Cat-3, the properties of which are shown in Table 1. Example 4

[0036] The same as example 1, except that the amount of pseudo-boehmite added in step (1) is 800 g, and the liquid-solid mass ratio during stirring is 9:1. In step (2), the concentration of propylene oxide is 7.7%, and the amount of solution used is 450 g. During hydrothermal treatment, first, the solution is treated at 65°C for 3.5 hours, then the temperature is raised to 130°C, and the treatment time is 19 hours, to obtain the silicon capturing agent Cat-4, the properties of which are shown in Table 1.

[0037] Comparative Example 1

[0038] The same as example 3, except that the propylene oxide aqueous solution is replaced by an aqueous ammonia solution of the same mass concentration, to obtain the comparative silicon capturing agent DC-1, the properties of which are shown in Table 1.

[0039] Comparative Example 2

[0040] The same as example 3, except that the propylene oxide aqueous solution is replaced by an ethylene oxide solution of the same concentration, to obtain the comparative silicon capturing agent DC-2, the properties of which are shown in Table 1.

[0041] Comparative Example 3

[0042] The same as example 3, except that the concentration of propylene oxide is 1%, to obtain the comparative silicon capturing agent DC-3, the properties of which are shown in Table 1.

[0043] Comparative Example 4

[0044] The same as example 3, except that the sealed heat treatment is one-step hydrothermal treatment, the treatment temperature is 85°C, and the treatment time is 20 hours, to obtain the comparative silicon capturing agent DC-4, the properties of which are shown in Table 1.

[0045] Comparative Example 5

[0046] The same as example 3, except that the mixture was not transferred into an autoclave for sealing treatment, but was subjected to normal pressure reflux treatment in a condensation reflux device, to prepare a comparative silicon capturing agent DC-5, the properties of which are shown in Table 1.

[0047] Table 1

[0048]

[0049] As can be seen from the data in Table 1, the silicon capturing agent prepared by the method of the present application has a higher hydroxyl content compared with the comparative silicon capturing agent. Example 5

[0050] The silicon capturing agents Cat-1, Cat-2, Cat-3 and Cat-4 of the present application and the silicon capturing agents DC-1, DC-2, DC-3, DC-4 and DC-5 of the comparative examples were respectively loaded into a fixed bed hydrogenation reactor, and their silicon capturing activities were investigated. The evaluation feedstock oil used was coking naphtha feedstock provided by a refinery of SINOPEC, the main properties of which were as follows: silicon content 114 μg / g. The evaluation reaction conditions were: operating pressure 3.0 MPa, reaction temperature 280℃, hydrogen / oil volume ratio 300:1, volume space velocity 5.0 h-1. After running for 300 h, the silicon capturing agent was unloaded, then was calcined at 500℃ for 3 h in a nitrogen atmosphere, and the SiO2 content in the silicon capturing agent was analyzed by XRF, and the evaluation results are shown in Table 2. -1

[0051] Table 2

[0052] Catalyst No. silicon content (as SiO2), % Cat-1 20.2 Cat-2 32.4 Cat-3 35.1 Cat-4 33.6 DC-1 9.8 DC-2 9.1 DC-3 12.2 DC-4 12.8 DC-5 7.5

[0053] As can be seen from Table 2, the silicon capturing agent of the present application has a very high silicon carrying capacity.​

Claims

1. A method of desiliconizing an oil product, characterized by: The silicon capturing agent is contacted with oil; the silicon capturing agent comprises an alumina carrier and flaky pseudo-boehmite grown in situ on the surface of the alumina carrier; the alumina carrier is a spherical particle aggregate, and the alumina carrier contains a microscale spherical cavity inside; the flaky pseudo-boehmite is grown in situ on the outer surface of the alumina carrier and in the microscale spherical cavity; the surface hydroxyl content of the silicon capturing agent is 1000-2000 µmol / g; the microscale spherical cavity filling rate is 45.7%-80%, wherein the filling rate refers to the percentage of the volume of the flaky pseudo-boehmite particles in the microscale spherical cavity to the volume of the microscale spherical cavity; and the preparation method of the silicon capturing agent comprises the following steps: (1) preparing an alumina carrier precursor containing a microscale spherical cavity; (2) immersing the alumina carrier precursor obtained in step (1) in an epoxy propane aqueous solution, sealing and heat treating, and then performing solid-liquid separation on the treated material, and drying the solid material to obtain the silicon capturing agent; in step (2), the mass percentage concentration of the epoxy propane aqueous solution is 2.5%-12%, and the mass ratio of the epoxy propane aqueous solution to the alumina carrier precursor is 3:1-10:1; in step (2), the sealing heat treatment is performed in a sealed container, and the sealing heat treatment is first performed at 60-100 ℃ for 1-4 hours, and then sealing treatment is performed at 110-180 ℃ for 14-20 hours.

2. The method of claim 1, wherein: The particle size of the flaky pseudo-boehmite is 100-600 nm.

3. The method of claim 1, wherein: The surface hydroxyl content of the silicon capturing agent is 1200-1800 µmol / g.

4. The method of claim 1, wherein: The outer surface coverage of the alumina carrier is 85%-100%, wherein the coverage refers to the percentage of the flaky pseudo-boehmite particles on the outer surface of the alumina carrier to the outer surface of the alumina carrier.

5. The method of claim 1, wherein: The grain size of the spherical particles is 80-200 nm.

6. The method of claim 1, wherein: In the preparation method of the silicon capturing agent, the alumina carrier precursor containing a microscale spherical cavity in step (1) is γ phase alumina; the diameter of the microscale spherical cavity is 1-10 microns, and the pore volume of the microscale spherical cavity accounts for 1%-30% of the total pore volume of the alumina carrier precursor.

7. The method of claim 1, wherein: In the preparation method of the silicon capturing agent, the mass percentage concentration of the epoxy propane aqueous solution in step (2) is 4%-8%, and the mass ratio of the epoxy propane aqueous solution to the alumina carrier precursor is 4:1-8:

1.

8. The method of claim 1, wherein: In the preparation method of the silicon capturing agent, the sealing heat treatment in step (2) is performed in a sealed container, and the sealing heat treatment is first performed at 60-100 ℃ for 1-4 hours, and then sealing treatment is performed at 120-160 ℃ for 14-20 hours.

9. The method of claim 1, wherein: In the preparation method of the silicon capturing agent, the drying temperature in step (2) is 100-160 ℃, and the drying time is 2-8 hours.

10. The method of claim 1, wherein: The oil product desilication is carried out in a fixed bed reactor, and the oil product is contacted with the desilication agent to form a catalyst bed in the reactor; the reaction conditions are as follows: the reaction temperature is 180-320 DEG C, the pressure is 2.0-8.0 MPa, the hydrogen / oil ratio is 100:1-1000:1; the oil product is one or more of coking naphtha and coking diesel, and the silicon content is 1-2000 ppm.

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