A method for preparing a composite alumina desulfurization adsorbent

Abstract

The present invention provides a composite alumina desulfurization adsorbent and a preparation method thereof. The preparation method comprises: adding a prepared activated alumina template agent to an alkaline solution, stirring to obtain a clear solution; adding boron nitride (BN) edge-loaded platinum (Pt) nanoparticles to the clear solution, stirring to obtain a suspension; adding alumina powder to the suspension for stirring reaction, filtering, drying and roasting after the reaction to obtain a composite alumina desulfurization adsorbent, wherein the mass ratio of the template agent to the alkali is (1-25): (15-55), and the mass ratio of the template agent, alumina powder and edge-loaded Pt nanoparticles BN is (2-18): (70-77): 30. The desulfurization adsorbent of the present invention has high adsorption capacity, good selection, high desulfurization accuracy, can be recycled and reused, and has a long service life.

Description

Technical Field

[0001] The present invention relates to a method for preparing a composite alumina desulfurization adsorbent, and in particular to a method for preparing a composite alumina desulfurization adsorbent that can be used for efficient desulfurization, belonging to the technical field of adsorption desulfurization. Background Art

[0002] With the rapid development of society and economy, the use of motor vehicles is also growing rapidly. The rapid growth of the number of motor vehicles has caused a continuous increase in fuel consumption and a series of environmental pollution problems. The sulfur content in fuel is the most critical environmental indicator in motor vehicle fuel. The use of high-sulfur fuel will not only increase the emission of toxic sulfur oxides, but also reduce the efficiency of the vehicle's own emission reduction components, thereby increasing the emission of substances such as carbon monoxide and nitrogen oxides. These are also important components in the formation of haze. Reducing the sulfur content in fuel, improving fuel quality, and alleviating environmental pollution are the main purposes of current fuel desulfurization. At present, the high hydrogen consumption, high energy consumption, and octane number loss caused by the existing catalytic hydrodesulfurization technology in the deep hydrogenation process have become the bottleneck problem of current technological development. In order to achieve deep desulfurization under the premise of low cost, low energy consumption, and mild conditions, non-hydrodesulfurization technologies such as oxidative desulfurization, extractive desulfurization, and adsorption desulfurization have gradually gained widespread attention from domestic and foreign researchers. Adsorption desulfurization technology has become one of the most promising desulfurization technologies due to its low cost, high desulfurization rate, and mild reaction conditions.

[0003] A Chinese invention patent (CN106563410A) discloses an active boron nitride desulfurizer. This invention uses active boron nitride to perform adsorption desulfurization on sulfur-containing fuel, which reduces the octane number of the fuel and increases the fuel adsorption desulfurization rate. However, the conditions for adsorption desulfurization of this method include that the sulfur content of the oil product is ≥150ppm, the organic sulfide is dibenzothiophene, and the real oil product used is a product after hydrogenation treatment. Because of its high sulfide content, the variety of organic sulfides is single, and additional reaction conditions need to be applied, the cost of desulfurization and energy consumption are increased.

[0004] A Chinese invention patent (CN106824043A) discloses a method for preparing an amorphous boron nitride adsorbent. This invention involves mixing and stirring boric acid, urea, water, and methanol, and evaporating the evaporated solid, and calcining the evaporated solid in a tubular furnace to obtain the adsorbent. Although this adsorbent can adsorb sulfides in fuel, the temperature needs to be 800-900°C, which increases the desulfurization cost and energy consumption.

[0005] Although boron nitride has strong desulfurization activity, it still has certain limitations in removing disulfides and small molecular mercaptans contained in petroleum gas. This is because disulfides are neutral organic sulfides. When physically adsorbing organic sulfides, the conventionally used boron nitride has a low central electric field strength and a low capacity for neutral organic sulfides. In addition, boron nitride is a non-metallic desulfurizer and lacks metal ions that bind to the thiol functional group in the thiol, making it impossible to achieve selective adsorption of it.

[0006] In summary, the existing preparation methods of boron nitride desulfurizers have the problems of high energy consumption, low sulfur adsorption capacity, frequent regeneration, single adsorption effect, and no research on the removal of trace sulfides. Summary of the invention

[0007] The present invention provides a preparation method and application of a composite alumina desulfurization adsorbent, thereby solving some problems existing in the existing production process:

[0008] The technical problems to be solved by the present invention are: (1) low sulfur adsorption capacity and frequent regeneration; (2) single desulfurization effect and poor adsorption effect of various sulfides.

[0009] The present invention is achieved through the following technical solutions:

[0010] A method for preparing a composite alumina desulfurization adsorbent, characterized in that the method comprises the following steps:

[0011] (a) adding a template agent for preparing activated alumina into an alkaline solution and stirring to obtain a clear solution;

[0012] (b) adding BN with edge-loaded Pt nanoparticles to the clear solution and stirring to obtain a suspension;

[0013] (c) adding alumina powder to the suspension to carry out stirring reaction, filtering, drying and roasting after the reaction to obtain a composite alumina desulfurization adsorbent;

[0014] in:

[0015] The mass ratio of the template to the base is (1-25): (15-55), and the mass ratio of the template, the alumina powder, and the BN of the edge-loaded Pt nanoparticles is (2-18): (70-77): 30;

[0016] The edge-loaded Pt nanoparticles BN is obtained by fixing Pt nanoparticles on the edge of BN using boron nitride as a carrier through an impregnation thermal reduction method, wherein the mass content of Pt is 0.5% to 2.0% of the total mass of Pt and boron nitride calculated as platinum dioxide.

[0017] In the above method, preferably, the template agent is a combination of one or more selected from dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and P123 template agent.

[0018] In the above method, preferably, the alkaline solution is a sodium hydroxide solution with a concentration of 0.5 to 2.0 mol / L.

[0019] In the above method, preferably, the alumina powder crystal form is one of α-Al2O3, β-Al2O3, and γ-Al2O3.

[0020] In the above method, preferably, in step (c), the alumina powder is added to the suspension and stirred for a reaction time of 20 to 60 hours; the calcination temperature is 350 to 550° C., and the calcination time is 3 to 6 hours.

[0021] In the above method, preferably, the boron nitride is a combination of one or more selected from hexagonal boron nitride (HBN), rhombohedral boron nitride (RBN), cubic boron nitride (CBN) and wurtzite boron nitride (WBN).

[0022] In the above method, preferably, the Pt nanoparticles are a combination of one or more selected from chloroplatinic acid, chloroplatinate, tetraamineplatinum acetate and platinum acetylacetonate.

[0023] In the above method, preferably, after adding the Pt nanoparticles, the calcination temperature is 550° C. to 650° C. and the calcination time is 2 to 3 hours.

[0024] In the gasoline desulfurization method provided by the present invention, the sulfides contained in the fuel oil are mercaptans, thioethers, thiophenes and their derivatives.

[0025] Beneficial effects of the present invention:

[0026] The present invention uses composite alumina as a desulfurization adsorbent. Adsorption desulfurization is carried out under mild conditions (such as normal temperature and pressure), with low operating costs (low temperature reaction), good desulfurization effect, and can still maintain good desulfurization performance after regeneration. The innovation of the present invention is mainly reflected in two aspects: first, compared with boron nitride-loaded platinum particles, activated alumina has a high adsorption capacity and a low regeneration frequency; second, composite alumina significantly improves the adsorption and removal capabilities of various sulfides, and can be used for the efficient removal of mercaptans, sulfides, thiophenes and their derivatives in petroleum products, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A process flow chart for preparing composite alumina desulfurization adsorbent;

[0028] Figure 2This is a SEM image of the composite alumina desulfurization adsorbent surface at 500 μm prepared in Example 2;

[0029] Figure 3 This is a SEM image of the composite alumina desulfurization adsorbent surface at 10 μm prepared in Example 2; DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] Attached Figure 1 This is a process flow chart for preparing the composite alumina desulfurization adsorbent of the present invention, which clearly expresses the preparation process of the composite alumina desulfurization adsorbent.

[0032] Example 1: Preparation of Boron Nitride Loaded with Pt Nanoparticles by Impregnation Thermal Reduction

[0033] Weigh 0.1g of Pt nanoparticles into a 30mL glass reaction bottle and dissolve with 10mL of acetone until transparent. Weigh 1g of boron nitride into the bottle, stir magnetically for 3h, and then dry in vacuum at 100℃. Put the light yellow sample into a tube furnace and keep it at 600℃ for 3h under nitrogen atmosphere to obtain boron nitride loaded with Pt nanoparticles.

[0034] Example 2: Preparation of composite alumina desulfurization adsorbent

[0035] Weigh 15g of hexadecyltrimethylammonium bromide, add it to 350ml of 2.0mol / L NaOH solution, and stir until it is completely dissolved to form a clear solution; put 50g of boron nitride loaded with Pt nanoparticles in Example 1 into the clear solution, stir for 3h under constant temperature stirring conditions (25°C, 220rpm) to form a suspension, add 72g of alumina powder to the solution, and stir vigorously for 30h after the addition; filter after stirring, and dry in a constant temperature furnace at 600°C for 2h to obtain a composite alumina desulfurization adsorbent.

[0036] Test Example 1: Composition Analysis of Sulfur-Containing Fuel

[0037] Test sample: Sulfur-containing fuel, the content of which is shown in Table 1.

[0038] Table 1 Composition of sulfur-containing fuel oil

[0039]

[0040] Test Example 2: Characterization of composite alumina desulfurization adsorbent

[0041] Test sample: Example 2 composite alumina desulfurization adsorbent.

[0042] Parameter characterization of composite alumina desulfurization adsorbent.

[0043] The particle size distribution of the adsorbent was measured using a laser particle size analyzer. The surface morphology and internal structure of the adsorbent were observed using a scanning electron microscope (SEM, S3400N, Hitachi, Japan). The specific surface area, pore volume and pore size distribution of each adsorbent were compared using an adsorption-microcalorimetry system (3Flex, Micromeritics, USA).

[0044] Particle size characterization experimental steps: 10g of composite alumina desulfurization adsorbent is placed in 20g of deionized water to make an adsorbent sample. The sample is first transferred to the measurement area of ​​the host through a sample preparation device. After the laser irradiates the sample, a light scattering signal is generated. At this time, the photodetector array converts the light scattering signal into an electrical signal, and then the electrical signal is transmitted to the computer via USB. Finally, a particle size distribution report of the sample is obtained. According to the test, the average particle size of the composite alumina desulfurization adsorbent is 0.2-0.5mm.

[0045] Surface morphology characterization experimental steps: The prepared sample is evenly spread on a copper table with a conductive sheet. After gold spraying, it is observed using a scanning electron microscope. By selecting magnifications of 100 and 5000, it can be seen that the surface of the desulfurizer is a porous structure with a large pore size, which is conducive to the removal of large molecular sulfides.

[0046] Experimental steps for characterizing physical property parameters: Place the prepared sample in a sample tube, use nitrogen as the adsorbent, and helium or hydrogen as the carrier gas. The two gases are mixed in a certain proportion to reach a specified relative pressure, and then flow through the solid material. When the sample tube is placed in liquid nitrogen for heat preservation, the sample physically adsorbs the nitrogen in the mixed gas, while the carrier gas is not adsorbed. At this time, an adsorption peak appears on the screen. The specific surface area, pore size, and pore volume of the desulfurizer are calculated, as shown in Table 2.

[0047] Table 2 Physical and chemical parameters of desulfurizer

[0048]

[0049] Test Example 3: Desulfurization

[0050] Test sample: Example 2 composite alumina desulfurization adsorbent.

[0051] Sample to be processed: Sulfur-containing fuel in Test Example 1

[0052] The experimental instruments required for the adsorption test are shown in Table 3.

[0053] Table 3 Instruments required for adsorption experiments

[0054]

[0055] Test steps: 1g of adsorbent was added to 800L of sulfur-containing fuel oil, and a batch adsorption experiment was performed under constant temperature stirring conditions (25°C, 220rpm). In order to obtain the total sulfur content and content changes of each main component in the sulfur-containing fuel oil samples at different sampling times, 0.5mL of the sulfur-containing fuel oil supernatant was taken at a predetermined time interval, and the total sulfur content in the alkylation oil sample was determined using an ultraviolet fluorescence sulfur detector, and the content changes of each main component in the sulfur-containing fuel oil were determined using a sulfur speciation analyzer.

[0056] Test results: The composite alumina desulfurization adsorbent of the present invention was used in a batch adsorption experiment for desulfurization treatment, and the adsorption rate reached 94%. The sulfur content in the fuel after treatment was below 0.8ppm, and the adsorption rate of thiophene sulfides reached 99%. From the above, it can be seen that the composite alumina desulfurization adsorbent has a good adsorption of macromolecular sulfides, indicating that the boron nitride mixed with Pt nanoparticles has increased the pore structure, which is conducive to the diffusion and adsorption of sulfides.

Claims

1. A method for preparing a composite alumina desulfurization adsorbent, characterized in that: The method comprises the following steps: (a) adding a template agent for preparing activated alumina into an alkaline solution and stirring to obtain a clear solution; (b) adding BN with edge-loaded Pt nanoparticles to the clear solution and stirring to obtain a suspension; (c) adding alumina powder to the suspension to carry out stirring reaction, filtering, drying and roasting after the reaction to obtain a composite alumina desulfurization adsorbent; in: The mass ratio of the template to the base is (1-25): (15-55), and the mass ratio of the template, the alumina powder, and the BN of the edge-loaded Pt nanoparticles is (2-18): (70-77): 30; The edge-loaded Pt nanoparticles BN is obtained by fixing Pt nanoparticles on the edge of BN using boron nitride as a carrier through an impregnation thermal reduction method, wherein the mass content of Pt is 0.5% to 2.0% of the total mass of Pt and boron nitride calculated as platinum dioxide.

2. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: The template agent is a combination of one or more selected from dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and P123 template agent.

3. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: The alkaline solution is a sodium hydroxide solution with a concentration of 0.5-2.0 mol / L.

4. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: The alumina powder has a crystal form of α-Al2O3, β-Al2O3, and γ-Al2O3.

5. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: In the step (c), the aluminum oxide powder is added to the suspension and stirred for a reaction time of 20 to 60 hours; the calcination temperature is 350 to 550° C., and the calcination time is 3 to 6 hours.

6. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: The boron nitride is a combination of one or more selected from hexagonal boron nitride HBN, rhombohedral boron nitride RBN, cubic boron nitride CBN and wurtzite boron nitride WBN.

7. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: The Pt nanoparticles are a combination of one or more selected from chloroplatinic acid, chloroplatinate, tetraamineplatinum acetate and platinum acetylacetonate.

8. The method for preparing the composite alumina desulfurization adsorbent according to claim 1, characterized in that: After adding Pt nanoparticles, the calcination temperature is 550° C. to 650° C., and the calcination time is 2 to 3 hours.

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