A method for removing silicon from oil products

Abstract

The present invention discloses a method for removing silicon from oil products, using the following composite oxide as a silicon scavenger, which is contacted and reacted with the oil product; the composite oxide is a mixed phase of γ-Al2O3 and pseudo-boehmite, wherein the pseudo-boehmite grains are in-situ directionally grown on the outer surface of the γ-Al2O3, forming a flaky structure. The silicon scavenger used in the oil removal method of the present invention is γ-Al2O3 coated with pseudo-boehmite. The pseudo-boehmite on the surface imparts a high surface hydroxyl content to the composite oxide, thereby imparting it with strong silicon-capturing and silicon-retention capabilities. The composite oxide has a high silicon removal capacity during oil removal and a long service life.

Description

Technical Field

[0001] The invention belongs to the field of petroleum refining, and in particular relates to a method for removing silicon from oil products. Background Art

[0002] Currently, my country still has a large number of delayed coking units processing heavy, low-quality oil. Defoamers are used during this process, resulting in a certain amount of silicon in products such as coker dry gas, coker naphtha, and coker diesel. This silicon poisons the catalysts used in subsequent coking product processing, leading to permanent catalyst deactivation. Therefore, the hydroprocessing of coker dry gas, coker naphtha, and coker diesel requires the installation of silicon-capturing catalysts.

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

[0004] CN201911020775.4 discloses an oil product silicon scavenger and its preparation method. The oil product silicon scavenger comprises a carrier and a hydrogenation active component, wherein the hydrogenation active component is a Group VIII metal sulfide, a Group VIB metal oxide, and a Group VIII metal oxide. Based on the total weight of the silicon scavenger, 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%. The preparation method comprises the following: (1) impregnating the silicon scavenger carrier with an impregnation solution containing a Group VIII metal, then drying the dried material, and sulfurizing the dried material; (2) impregnating the sulfurized material in step (1) with an impregnation solution containing Group VIB and Group VIII metals, and then drying and calcining the material under an inert atmosphere to obtain the oil product silicon scavenger.

[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 method for removing silicon from oil products, using a composite oxide having a large specific surface area and pore volume, especially a high surface hydroxyl content, which can exert a high silicon-containing capacity in oil product removal and achieve better silicon removal effect.

[0007] In the context of this specification, FTIR (infrared spectroscopy) was used to analyze the 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 integrated intensity is calculated. The specific surface area of ​​the silicon capture 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 the ASAP 2420 nitrogen physical adsorption instrument of MICROMERITICS of the United States is used to perform N2 adsorption and desorption tests at a temperature of 77K. The grain size is calculated using the XRD spectrum, specifically according to the Scherrer formula: D = (K*γ) / (B*cosθ), where K is the Scherrer constant. If B is the half-maximum width of the diffraction peak, then K = 0.89; D is the grain size; B is the half-maximum width of the diffraction peak of the measured sample; θ is the Bragg angle; γ is the wavelength of the X-ray, which is The microstructure of the silicon scavenger was characterized by scanning electron microscopy. The specific operation was as follows: the microstructure of the silicon scavenger 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 present invention provides a method for removing silicon from oil products, which uses the following composite oxide as a silicon scavenger to react with the oil products in contact; the composite oxide is a mixed phase of γ-Al2O3 and pseudo-boehmite, wherein the pseudo-boehmite grains are in-situ directionally grown on the outer surface of the γ-Al2O3, the pseudo-boehmite grains form a flaky structure, the size of the pseudo-boehmite grains is 3.0-15.0nm, and the particle size of the flaky structure is 100-400nm; the ratio H of the grain size of the crystal plane corresponding to the pseudo-boehmite (120) peak to the grain size of the crystal plane corresponding to the γ-Al2O3 (440) peak is 3.5-5.0, and H=D AlOOH (120) / D γ-Al2O3(440), wherein D(120) represents the grain size of the crystal plane corresponding to the pseudo-boehmite (120) peak in the XRD spectrum; the 120 peak refers to the characteristic peak with 2θ of 25.5-29.9° in the XRD spectrum; the D(440) represents the grain size of the crystal plane corresponding to the γ-Al2O3 (440) peak in the XRD spectrum; the 440 peak refers to the characteristic peak with 2θ of 63.6-69.1° in the XRD spectrum.

[0009] Furthermore, the surface hydroxyl content of the composite oxide is 1000-2000 μmol / g, preferably 1200-1800 μmol / g. The specific surface area is 300-500m 2 / g, preferably 350-450m 2 / g.

[0010] Furthermore, the coverage of the pseudo-boehmite on the outer surface of γ-Al2O3 is 85%-100%, preferably 88%-98%, and most preferably 90%-97%, wherein the coverage is the percentage of the surface occupied by the lamellar pseudo-boehmite grains to the outer surface of γ-Al2O3.

[0011] Furthermore, the shape of the composite oxide is the conventional shape of the catalyst in the prior art. Generally, it can be spherical with a particle size of 1-8.0 mm. It can also be a strip catalyst with a circular, clover-shaped or four-leaf clover-shaped cross-section, with a cross-sectional diameter of 0.2-3.0 mm and a length of 3-8.0 mm.

[0012] Furthermore, the composite oxide is prepared by the following method:

[0013] (1) mixing γ-Al2O3 powder, an extrusion aid, and a peptizing agent, kneading and forming, drying, and calcining to obtain an alumina carrier precursor;

[0014] (2) Immersing the alumina carrier precursor prepared in step (1) in an aqueous solution of propylene oxide for sealed heat treatment, separating the treated material into solid and liquid, and drying the solid phase material to obtain the composite oxide.

[0015] Furthermore, the γ-Al2O3 powder described in step (1) can be prepared by any method known to those skilled in the art, wherein the γ-Al2O3 powder having a pore volume of pores with a diameter of 8-15 nm and accounting for more than 70% of the total pore volume is preferred. The extrusion aid is sesbania powder, added in an amount of 0.5wt%-3.5wt% based on 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, added in an amount of 0.5wt%-5.5wt% based on the weight of the alumina. The drying temperature is 100-160°C, and the drying time is 6-10 hours; the calcination temperature is 500-800°C, and the calcination time is 4-6 hours; and the calcination is carried out in an oxygen-containing atmosphere, preferably in air.

[0016] Furthermore, the specific surface area of ​​the alumina carrier precursor obtained in step (1) is 300-450m 2 / g, pore volume 0.7-1.2mL / g. The pore volume of pores with a diameter of 6-15nm accounts for more than 80% of the total pore volume.

[0017] Furthermore, the mass concentration of propylene oxide in 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 alumina carrier is 3:1-10:1, preferably 4:1-8:1.

[0018] 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 14-20 hours, preferably 16-20 hours.

[0019] Furthermore, the drying temperature in step (2) is 100-160° C., and the drying time is 2-8 hours.

[0020] 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.

[0021] The oil desiliconization process is carried out in a fixed-bed reactor. The catalyst bed is formed by loading the composite oxide into the reactor, which then reacts with the oil. The reaction conditions are as follows: a temperature of 180-320°C, a pressure of 2.0-8.0 MPa, and a hydrogen-to-oil ratio of 100:1-1000:1.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The silicon scavenger used in the method for removing silicon from oil products of the present invention is γ-Al2O3 with pseudo-boehmite on the surface. The pseudo-boehmite on the surface gives the composite oxide a high surface hydroxyl content, thereby making it have a strong silicon scavenging and silicon accommodating ability. It has a high silicon removal ability in oil product removal and a long service life.

[0024] (2) The composite oxide used in the present invention is obtained by placing an alumina carrier precursor in a propane solution and sealing and heat-treating it. 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 grains on the surface of the alumina carrier grow outward in situ in the alkaline and alcohol solution environment and form flaky pseudo-boehmite particles. The pseudo-boehmite particles have a high coverage rate on the outer surface of the alumina carrier, thereby increasing the specific surface area and pore volume of the silicon scavenger, which is beneficial to improving the silicon holding capacity of the silicon scavenger. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD spectra of the alumina carrier precursor and the silicon trap Cat-1 prepared in Example 1.

[0026] Figure 2 This is the SEM image of the surface of the silicon scavenger Cat-1 prepared in Example 1. DETAILED DESCRIPTION

[0027] 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.

[0028] Alumina support precursor preparation:

[0029] Weigh 500 g of pseudo-boehmite (prepared by aluminum sulfate-sodium aluminate method), add 2.5 g of sesbania powder, then add an appropriate amount of 3.0% nitric acid solution to the mixture and knead it evenly. Extrusion molding, the molding material is dried at 120 ° C for 8 hours and calcined at 500 ° C for 5 hours to obtain an alumina carrier precursor S0. The properties of the alumina carrier precursor are shown in Table 1, and the XRD spectrum is shown in Figure 1 A.

[0030] Example 1

[0031] (1) Weigh 100 g of the alumina carrier precursor S0, 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 18 hours. After treatment, the material is cooled, washed, and filtered, and the solid material is dried at 120°C for 6 hours to obtain a silicon trap Cat-1. The XRD spectrum of Cat-1 is shown in FIG. Figure 1B, Cat-1 properties are shown in Table 1, and the scanning electron microscope image of the Cat-1 outer surface is shown in Figure 2 .

[0032] Example 2

[0033] The same as Example 1, except that the concentration of propylene oxide in step (1) 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 17.5 hours to obtain the silicon scavenger Cat-2 of the present invention. The properties are shown in Table 1.

[0034] Example 3

[0035] The same as Example 1, except that the concentration of propylene oxide in step (1) 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 16 hours to obtain the silicon scavenger Cat-3 of the present invention. The properties are shown in Table 1.

[0036] Example 4

[0037] The same as Example 1, except that the concentration of propylene oxide in step (1) 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 19 hours to obtain the silicon scavenger Cat-4 of the present invention. The properties are shown in Table 1.

[0038] Comparative Example 1

[0039] 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.

[0040] Comparative Example 2

[0041] 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.

[0042] Comparative Example 3

[0043] 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.

[0044] Comparative Example 4

[0045] 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.

[0046] Table 1

[0047]

[0048] It can be seen from the data in Table 1 that, compared with the silicon scavenger in the comparative example, the silicon scavenger prepared by the method of the present invention has a higher hydroxyl content.

[0049] Example 5

[0050] The silicon scavengers Cat-1, Cat-2, Cat-3, and Cat-4 prepared by the present invention and the silicon scavengers DC-1, DC-2, DC-3, and DC-4 prepared by the comparative example were respectively loaded into a fixed bed hydrogenation reactor to examine their silicon scavenging activity. The raw oil used for evaluation was coking naphtha provided by a refinery of Sinopec, and its main properties were as follows: silicon content was 124 μg / g. The evaluation reaction conditions were: operating pressure 3.0 MPa, reaction temperature 290°C, hydrogen / oil volume ratio 200:1, volume space velocity 4.0 h -1 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.

[0051] Table 2.

[0052] Catalyst No. <![CDATA[Silicon content (calculated as SiO2), % <!-- 4 -->]]> Cat-1 18.1 Cat-2 30.2 Cat-3 33.1 Cat-4 31.3 DC-1 8.1 DC-2 7.9 DC-3 10.8 DC-4 11.5

[0053] As can be seen from Table 2, the silicon scavenger of the present invention has a very high silicon holding capacity.

Claims

1. A method for removing silicon from oil products, characterized in that: The following composite oxide is used as a silicon scavenger and is in contact with the oil product for reaction; the composite oxide is a mixed phase of γ-Al2O3 and pseudo-boehmite, wherein the pseudo-boehmite grains are in-situ directionally grown on the outer surface of γ-Al2O3, the pseudo-boehmite grains form a flaky structure, the size of the pseudo-boehmite grains is 3.0-15.0nm, and the particle size of the flaky structure is 100-400nm; the ratio H of the grain size of the crystal plane corresponding to the pseudo-boehmite (120) peak to the grain size of the crystal plane corresponding to the γ-Al2O3 (440) peak is 3.8-5.0, H=D AlOOH (120) / D γ-Al2O3 (440), where D AlOOH (120) represents the crystal size of the crystal plane corresponding to the (120) peak of pseudo-boehmite in the XRD spectrum; the (120) peak refers to the characteristic peak with 2θ of 25.5-29.9° in the XRD spectrum; the D γ-Al2O3 (440) represents the grain size of the crystal plane corresponding to the γ-Al2O3 (440) peak in the XRD spectrum; the (440) peak refers to the characteristic peak with a 2θ value of 63.6-69.1° in the XRD spectrum; The surface hydroxyl content of the composite oxide is 1000-2000 μmol / g; The composite oxide is prepared by the following method: (1) Mixing γ-Al2O3 powder, an extrusion aid and a peptizing agent, kneading and forming, drying and calcining to obtain an alumina carrier precursor; (2) immersing the alumina carrier precursor prepared in step (1) in an aqueous solution of propylene oxide for sealed heat treatment, separating the treated material into solid and liquid, and drying the solid phase material to obtain the composite oxide; Wherein, the mass concentration of propylene oxide in the propylene oxide aqueous solution in step (2) is 2.5%-12%, and the mass ratio of the propylene oxide aqueous solution to the alumina carrier precursor is 3:1-10:1; The sealed heat treatment in step (2) is carried out in a sealed container. The sealed heat treatment is a two-step sealed heat treatment, firstly at 60-100°C for 1-4 hours, and then at 110-180°C for 14-20 hours.

2. The method according to claim 1, characterized in that The surface hydroxyl content of the composite oxide is 1200-1800 μmol / g.

3. The method according to claim 1, characterized in that The specific surface area of ​​the composite oxide is 300-500m 2 / g.

4. The method according to claim 3, characterized in that The specific surface area of ​​the composite oxide is 350-450m 2 / g.

5. The method according to claim 1, wherein The coverage rate of the pseudo-boehmite on the outer surface of γ-Al2O3 is 85%-100%.

6. The method according to claim 1, wherein The γ-Al2O3 powder described in step (1) is a γ-Al2O3 powder in which the pore volume of pores with a pore diameter of 8-15 nm accounts for more than 70% of the total pore volume.

7. The method according to claim 1, characterized in that The drying temperature in step (1) is 100-160° C., and the drying time is 6-10 hours; the roasting temperature is 500-800° C., and the roasting time is 4-6 hours; and the roasting is carried out in an oxygen-containing atmosphere.

8. The method according to claim 1, characterized in that The specific surface area of ​​the alumina carrier precursor obtained in step (1) is 300-450m 2 / g, pore volume 0.7-1.2mL / g; the pore volume of pores with a pore diameter of 6-15nm accounts for more than 80% of the total pore volume.

9. The method according to claim 1, characterized in that The drying temperature in step (2) is 100-160° C., and the drying time is 2-8 hours.

10. The method according to claim 1, characterized in that The oil product desiliconization is carried out in a fixed bed reactor, and the composite oxide is loaded into the reactor to form a catalyst bed layer, which contacts and reacts with the oil product.

11. The method according to claim 10, characterized in that The conditions for the oil desiliconization reaction are as follows: reaction temperature is 180-320°C, pressure is 2.0-8.0 MPa, and hydrogen-to-oil ratio is 100:1-1000:1.

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