Hydrodesulfurization catalyst as well as preparation method and application thereof

Abstract

The invention provides a hydrodesulfurization catalyst and a preparation method and application thereof, the preparation method of the hydrodesulfurization catalyst comprises the following steps: S1, dissolving an aluminum source in ethanol, dropwise adding acid, and stirring to obtain a solution A; dissolving a template agent in ethanol, and stirring to obtain a solution B; dropwise adding the solution A into the solution B, stirring, adding a cerium source, stirring, aging and calcining to obtain a CeO2-Al2O3 composite oxide carrier; s2, carrying out hydrothermal treatment on the CeO2-Al2O3 composite oxide carrier, and then carrying out acid treatment, so as to obtain a CeO2-Al2O3 carrier with regulated and controlled hydroxyl groups; and S3, loading the active component on the surface of the hydroxyl-regulated CeO2-Al2O3 carrier by adopting an impregnation method to obtain the hydrodesulfurization catalyst. According to the present invention, the activity and the stability of the catalyst can be improved, the agglomeration of the active metal is avoided, the selectivity and the catalytic activity are improved, and the catalyst is suitable for the advanced treatment of the inferior diesel oil high-sulfur compound difficult to remove.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and specifically relates to a hydrodesulfurization catalyst and a preparation method and application thereof. Background Art

[0002] In recent years, the demand for aviation kerosene has been growing steadily year by year, while the large amount of diesel consumption has aggravated air pollution. At the same time, the fuel emission regulations of various countries are becoming increasingly stringent, and the production of clean transportation fuel has become an urgent need. Considering that the sulfur content of diesel must be less than 10mg / kg -1 , and the most effective way to achieve this goal is to perform deep hydrodesulfurization (HDS) on most complex sulfur compounds, such as dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Therefore, the design and development of catalysts with the characteristics of targeted hydroconversion of complex structural sulfides is the key to achieving the production of ultra-low sulfur content clean fuels.

[0003] Existing hydroprocessing catalysts are mainly Ni(Co)Mo(W)S2 atomic crystals loaded on γ-Al2O3. The strong interaction between the metal phase and the γ-Al2O3 carrier makes most of the active metals dispersed on the catalyst surface in a single layer, which easily forms a Ni-Mo-S(I) structure instead of Ni-MoS(II). Compared with the Ni-Mo-S(II) phase with higher stacking and more active phase layers, the activity of Ni-Mo-S(I) is relatively low, which makes it difficult to sulfidize the active metals, showing that the catalyst has poor directional catalytic conversion ability for compounds containing complex sulfides. How to overcome the above problems of existing hydroprocessing catalysts and realize the directional hydrogenation of inferior diesel resources into low-freezing point ultra-clean high-density aviation kerosene with outstanding lubricity has become the focus of research. The activity of supported catalysts generally depends on the particle size and dispersion of the active components. Therefore, the preparation of new carrier materials and chemical modification of the carrier surface have become a reliable way to solve this problem. To this end, researchers at home and abroad have carried out a series of research work.

[0004] The Chinese patent application with publication number CN117563577A discloses a method for regulating the surface hydroxyl groups of a silica carrier for the preparation of a catalyst for synthesizing methyl methacrylate. The catalyst activity is improved by three different methods: ion thermal treatment, calcination treatment, and peroxide treatment of the carrier. The method is simple and easy to prepare, does not require the use of traditional organosiliconizing agents, and is suitable for subsequent large-scale industrial applications. However, the hydrodesulfurization performance of this type of catalyst needs to be further improved and still cannot meet the requirements of practical applications.

[0005] The Chinese patent application with publication number CN117699834A discloses a mesoporous pseudo-boehmite with a surface rich in hydroxyl groups and a preparation method thereof, wherein the pseudo-boehmite has a mesoporous pore size greater than 4.5 nm and not more than 12 nm. 3000～3800 6.0cm -1 mg -1 ~8.5cm -1 mg -1 . Its preparation method includes: reacting sodium aluminate solution with carbon dioxide gas, aging in stages under hydrothermal conditions in the presence of a hydroxyl regulator, washing and drying. The pseudo-boehmite prepared by it has high crystallinity, large grain size, large pore size, rich surface hydroxyl groups, and good peptization performance. However, the mesoporous pseudo-boehmite still has the problems of uneven loading of active metals and excessive interaction between the metal and the carrier, and the catalyst finally obtained does not show excellent performance.

[0006] A Chinese patent application with publication number CN107511178A discloses a method for modifying an alumina carrier and preparing a hydrogenation catalyst, wherein the vanadium additive is distributed in the shell layer of the carrier, and the modified alumina carrier is then immersed in a second solution of a compound containing an active metal component, and the hydrogenation catalyst is obtained by drying and calcining. The hydrogenation catalyst provided by the invention can achieve a high demetallization and desulfurization effect by controlling the layered distribution of the active metal component along the radial direction of the hydrogenation catalyst. However, in a specific hydrogenation process, it is impossible to control the difficult-to-remove metal to completely contact with the vanadium sulfide, so there is still a possibility that the metal is deposited at the catalyst pores, causing the catalyst pores to be blocked, and the active phase cannot be effectively utilized.

[0007] The Chinese patent application with publication number CN117225400A discloses a method for preparing a modified alumina carrier and its application. The modified alumina carrier prepared by the method comprises alumina, sodium, tungsten, zirconium and chromium; the BET specific surface area of ​​the modified alumina carrier is 300-400cm 2 / g, pore volume 0.5-1.2cm 3 / g, and the average pore size is 8-10nm. The preparation method of the modified alumina carrier is simple and efficient, and can promote the formation of mesopores to obtain a mesoporous carrier. Furthermore, when preparing the catalyst, the active sites and surface groups are coordinated to effectively inhibit the carbon deposition of the catalyst and increase its service life. The catalyst finally obtained can effectively improve the conversion rate of propane and the selectivity of propylene in the dehydrogenation of propane to propylene. However, it does not solve the problems of uneven dispersion of active metals, large particle size, and small metal surface area when loaded on an alumina carrier.

[0008] The Chinese patent application with publication number CN102059121A discloses a lanthanum-modified nickel-copper octanol hydrogenation refining catalyst and its preparation and application; the catalyst is prepared by impregnation method with γ-Al2O3 as carrier, lanthanum as auxiliary agent, nickel-copper as active component, and the content of aluminum oxide is 40% to 90% by mass percentage, the content of nickel is 1% to 40% in NiO, the content of copper is 1% to 30% in CuO, and the auxiliary lanthanum is 0.1% to 10% in La2O3; the catalyst has the excellent performance of high hydrogenation activity and good selectivity. However, the cost of using rare earth elements as modified materials is too high, and the industrial application is limited.

[0009] In summary, the main problem with the current hydrodesulfurization catalysts is that the commonly used catalyst carriers have structural and performance defects, which cannot meet the requirements of the directional hydrogenation conversion of complex sulfides on the geometric morphology and electronic structure of the active phase of the hydroprocessing catalyst to create high stacking and short crystalline atomic wafers. The effect on improving the matching between the hydrogenation activity and the hydrogenolysis activity of the catalyst is limited. At the same time, it cannot solve the problems of low dispersion of active metals on existing catalysts, difficult sulfurization and low efficiency of formation of type II NiMoS active phase. Summary of the invention

[0010] In order to solve the above-mentioned problems of the prior art, the present invention provides a hydrodesulfurization catalyst and a preparation method and application thereof, which can improve the activity and stability of the catalyst, while avoiding the agglomeration of active metals, improving the selectivity and catalytic activity. The prepared catalyst is suitable for deep treatment of high-sulfur compounds that are difficult to remove from inferior diesel.

[0011] The present invention is achieved through the following technical solutions:

[0012] A method for preparing a hydrodesulfurization catalyst comprises the following steps:

[0013] S1, dissolving the aluminum source in ethanol, adding acid dropwise, stirring, and obtaining solution A; dissolving the template in ethanol, stirring, and obtaining solution B; adding solution A dropwise to solution B, stirring, adding cerium source, stirring, aging, and calcining to obtain a CeO2-Al2O3 composite oxide carrier;

[0014] S2, subjecting the CeO2-Al2O3 composite oxide support to hydrothermal treatment and then acid treatment to obtain a hydroxyl-regulated CeO2-Al2O3 support;

[0015] S3, dissolving the precursor of the active component in water to obtain an impregnation solution; dropping the impregnation solution onto the surface of the hydroxyl-regulated CeO2-Al2O3 carrier, and then drying and calcining to obtain a hydrodesulfurization catalyst; wherein the active component includes Group VIB metals and Group VIII metals.

[0016] Preferably, in S1, the molar ratio of the aluminum source to the cerium source is (1-20):1.

[0017] Preferably, in S2, the CeO2-Al2O3 composite oxide support is hydrothermally treated, and the specific method is: place the CeO2-Al2O3 composite oxide support in a container, introduce air containing H2O, heat it to 400-800°C, keep it warm for 3-6 hours, and then naturally cool it to room temperature.

[0018] Preferably, in S2, the acid treatment is specifically: adding an acid solution to the CeO2-Al2O3 composite oxide support after hydrothermal treatment, stirring, and then filtering, washing, drying, and calcining to obtain a hydroxyl-regulated CeO2-Al2O3 support.

[0019] Furthermore, in S3, the Group VIB metal is molybdenum or tungsten, and the Group VIII metal is nickel or cobalt.

[0020] Furthermore, the Group VI B metal is molybdenum, and the Group VIII metal is nickel; the precursor of the active component includes a molybdenum-containing compound and a nickel-containing compound; wherein the molybdenum-containing compound is at least one of molybdenum oxide, molybdate and paramolybdate; and the nickel-containing compound is at least one of nickel nitrate, nickel acetate, basic nickel carbonate and nickel chloride.

[0021] Furthermore, in S3, the calcination temperature is 300-900° C., and the calcination time is 4-8 hours.

[0022] The present invention also provides a hydrodesulfurization catalyst obtained by the preparation method as described above.

[0023] Preferably, in the hydrodesulfurization catalyst, based on the total mass of the hydrodesulfurization catalyst, the content of the Group VIB metal component in terms of oxide is 0.5 wt% to 15 wt%, and the content of the Group VIII metal component is 5 wt% to 30 wt%.

[0024] The invention also provides application of the hydrodesulfurization catalyst in diesel hydrodesulfurization.

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

[0026] On the one hand, the present invention optimizes the carrier structure, selects cerium aluminum composite oxide as the carrier, gives full play to the advantages of CeO2 and Al2O3, and avoids the disadvantages of too strong MSI and too narrow controllable range of MSI on Al2O3-based catalysts; the mesoporous structure of the cerium aluminum composite oxide carrier can process larger molecules or groups, and small pore size particles are more conducive to the dispersion and migration of metal active components, reduce agglomeration, and enhance the long-term effectiveness and anti-sulfur ability of the catalyst; on the other hand, hydrothermal treatment can increase the number of silanol groups by increasing temperature and humidity, especially promote the generation of surface active sites such as silanol (Si-OH), hydroxysilanyl (SiO2-OH), aluminum hydroxyl (Al-OH), cerium hydroxyl (Ce-OH), and the like, and the hydration of materials such as aluminum oxide and silicon oxide, thereby enhancing the activity and stability of the catalyst; acid treatment mainly treats the carrier with an acidic solution (such as hydrochloric acid, sulfuric acid, etc.), which can reduce excessive acid sites, increase the content of surface hydroxyl groups, especially the concentration of surface hydroxide (H-OH) sites, adjust the surface acidity and alkalinity of the carrier, and thus improve the desulfurization performance of the catalyst. Especially in some hydrodesulfurization reactions, acidic sites can promote the adsorption and conversion of sulfides; hydrothermal treatment and acid treatment can complement each other, and by combining them, they can adjust the different types of hydroxyl groups on the support surface to achieve the optimization of catalyst performance. Hydrothermal treatment increases the number of silanol groups and surface hydration, improving the hydrophilicity of the catalyst, while acid treatment optimizes the acidity and alkalinity of the catalyst and metal dispersion by adjusting the acidic sites. This dual regulation can improve the stability, activity and selectivity of the catalyst, reduce the agglomeration of active metals, and significantly improve the hydrodesulfurization performance. If only hydrothermal treatment or acid treatment is used, there may be limitations in the regulation effect, and the advantages of the two methods cannot be fully utilized.

[0027] The hydrodesulfurization catalyst prepared by the present invention has abundant and controllable surface hydroxyl groups, has a significant deep hydrodesulfurization effect on inferior diesel, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 Schematic diagram of the hydroxyl migration mechanism under different treatment methods in the present invention.

[0030] Figure 2 These are the performance evaluation results of NiMo / CeO2-Al2O3 catalysts prepared in Examples 4 to 7 of the present invention and treated at different temperatures.

[0031] Figure 3 HRTEM images of the sulfided NiMo / CeO2-Al2O3 catalysts prepared in Examples 4 to 7 of the present invention. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0034] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0035] The method for preparing the hydrodesulfurization catalyst of the present invention comprises the following steps:

[0036] S1, dissolving the aluminum source in ethanol, adding acid dropwise, stirring, and obtaining solution A; dissolving the template in ethanol, stirring, and obtaining solution B; adding solution A dropwise to solution B, stirring, adding cerium source, stirring, aging, drying, and calcining to obtain a CeO2-Al2O3 composite oxide support;

[0037] S2, subjecting the CeO2-Al2O3 composite oxide support to hydrothermal treatment and then acid treatment to obtain a hydroxyl-regulated CeO2-Al2O3 support;

[0038] S3, dissolving the precursor of the active component in water to obtain an impregnation solution; dropping the impregnation solution onto the surface of the hydroxyl-regulated CeO2-Al2O3 carrier, and then drying and calcining to obtain a hydrodesulfurization catalyst; wherein the active component includes Group VIB metals and Group VIII metals.

[0039] The present invention optimizes the carrier structure, uses CeO2-Al2O3 composite oxide as the carrier, gives full play to the advantages of CeO2 and Al2O3, and avoids the disadvantages of too strong MSI and too narrow controllable range of MSI on Al2O3-based catalysts. Its mesoporous structure can handle larger molecules or groups; secondly, small pore size particles are more conducive to the dispersion and migration of metal active components, reduce agglomeration, and enhance the long-term effectiveness and sulfur resistance of the catalyst.

[0040] In S1 of the present invention, the aluminum source is a mixture of one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and aluminum isopropoxide, more preferably aluminum chloride and aluminum isopropoxide; the cerium source is a mixture of one or more of cerium nitrate, cerium chloride, and cerium sulfide, more preferably cerium nitrate and cerium sulfide; the template is a mixture of one or more of P123, F127, CTAB, and CTAC, more preferably P123 and F127; the acid is a mixture of one or more of hydrochloric acid, nitric acid, sulfuric acid, and acetic acid, more preferably hydrochloric acid or nitric acid.

[0041] As a preferred embodiment, the molar ratio of aluminum source + cerium source, template, ethanol, and acid is (0.03-0.5):(0.001-0.005):(0.5-5):(0.03-0.3), wherein the molar ratio of aluminum source to cerium source is (1-20):1.

[0042] In S1 of the present invention, the drying temperature is 60 to 120° C., and the drying time is 1 to 12 hours.

[0043] In order to control the hydroxyl content on the surface of the carrier, the present invention treats the CeO2-Al2O3 composite oxide carrier, firstly hydrothermally treats the carrier, then acid treats the carrier, controls the hydroxyl content on the surface of the cerium aluminum composite oxide carrier, reduces the possibility of subsequent loading of active components clustering, and significantly improves the hydrodesulfurization performance of the catalyst prepared. Figure 1 As shown in the figure, the migration of hydroxyl groups on the oxide surface mainly undergoes two processes: dehydration and hydrogen absorption. When the hydrothermal temperature begins to rise, the oxide undergoes a "dehydration reaction" to generate water molecules that escape from the oxide surface, thereby losing a large number of hydroxyl groups; but after reaching a certain temperature, the highly active oxide material causes surface oxygen vacancies under high-temperature roasting, and "absorbs hydrogen" (absorbs water molecules) during cooling to form hydroxyl groups. The hydroxyl groups on the surface of the hydroxylated oxide can be removed by controlling the appropriate concentration of acid, thereby regulating the OH density to provide suitable reaction sites for surface species.

[0044] The present invention can achieve precise control of the hydroxyl groups on the surface of the CeO2-Al2O3 carrier through the above method, thereby reducing the possibility of clustering of the subsequent loaded active components and improving the hydrodesulfurization performance.

[0045] Specifically, the specific process of S2 in the present invention is: placing a CeO2-Al2O3 composite oxide carrier in a container, passing air containing 10% H2O, heating to 400-800°C, keeping warm for 3-6 hours, and naturally cooling to room temperature after the end; adding an acid solution to the CeO2-Al2O3 composite oxide carrier after hydrothermal treatment, stirring for 1-2 hours, and then filtering, washing, drying, and calcining at a calcination temperature of 450-650°C to obtain a hydroxyl-regulated CeO2-Al2O3 carrier.

[0046] In the method of the present invention, the acid solution is one or more of nitric acid, hydrochloric acid and sulfuric acid, preferably hydrochloric acid and nitric acid, and the concentration thereof is 0.1 to 10 mol / L.

[0047] The Group VIB metal of the present invention is molybdenum or tungsten, more preferably molybdenum; the Group VIII metal is nickel or cobalt, more preferably nickel. The precursor of the active component preferably includes a molybdenum-containing compound and a nickel-containing compound; wherein the molybdenum-containing compound is at least one of molybdenum oxide, molybdate and paramolybdate; and the nickel-containing compound is at least one of nickel nitrate, nickel acetate, basic nickel carbonate and nickel chloride.

[0048] Based on the total mass of the hydrodesulfurization catalyst, the content of the Group VIB metal component in terms of oxide is 0.5 wt% to 15 wt%, and the content of the Group VIII metal component is 5 wt% to 30 wt%.

[0049] In the method of the present invention, in S3, the roasting temperature is 300-900° C. and the roasting time is 4-8 hours.

[0050] The hydrodesulfurization catalyst prepared by the invention can be used in the hydrodesulfurization process of diesel, and is more suitable for the hydrodesulfurization process of inferior diesel with high sulfur content.

[0051] Preparation of CeO2-Al2O3 composite oxide support:

[0052] Example 1

[0053] The raw materials were weighed according to the molar ratio of cerium source to aluminum source of 1:9. 2.04g aluminum isopropoxide was dissolved in 20mL ethanol, stirred for 4h, 2mL hydrochloric acid was added dropwise, and stirred for 15min, which was recorded as solution A; 2g F127 was dissolved in 10mL ethanol, stirred for 4h, and recorded as solution B; solution A was added dropwise to solution B, stirred for 2h, 0.47g cerium nitrate tetrahydrate was added, and stirred for 4h, and the resulting solution was aged at 50°C for 60h to obtain a light yellow solid; the light yellow solid was placed in a muffle furnace, heated to 500°C at a rate of 1°C / min and kept warm for 6h to obtain a CeO2-Al2O3 composite oxide carrier.

[0054] Example 2

[0055] The raw materials were weighed according to the molar ratio of cerium source to aluminum source of 2:8. 4.08g of aluminum isopropoxide was dissolved in 20mL of ethanol, stirred for 4h, 1.6mL of hydrochloric acid was added dropwise, and stirred for 15min, which was recorded as solution A; 8g of P123 was dissolved in 10mL of ethanol, stirred for 4h, and recorded as solution B; solution A was added dropwise to solution B, stirred for 2h, 1.76g of cerium nitrate tetrahydrate was added, and stirred for 4h, and the resulting solution was aged at 50°C for 60h to obtain a light yellow solid; the light yellow solid was placed in a muffle furnace, heated to 450°C at a rate of 1°C / min and kept warm for 4h to obtain a CeO2-Al2O3 composite oxide carrier.

[0056] Example 3

[0057] The raw materials were weighed according to the molar ratio of cerium source to aluminum source of 3:7. 4.08g of aluminum isopropoxide was dissolved in 20mL of ethanol, stirred for 4h, 3.2mL of nitric acid was added dropwise, and stirred for 15min, which was recorded as solution A; 4g of P123 was dissolved in 20mL of ethanol, stirred for 4h, and recorded as solution B; solution A was added dropwise to solution B, stirred for 2h, 3.72g of cerium nitrate tetrahydrate was added, and stirred for 4h, and the resulting solution was aged at 60°C for 48h to obtain a light yellow solid; the light yellow solid was placed in a muffle furnace, heated to 550°C at a rate of 1°C / min and kept warm for 4h to obtain a CeO2-Al2O3 composite oxide carrier.

[0058] Weigh 20 g of the carrier obtained in Example 3 above, and pre-treat the carrier using different methods. The specific methods are as follows.

[0059] Example 4

[0060] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 450℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 450℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 1mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier A.

[0061] Example 5

[0062] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 550℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 550℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 1mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier B.

[0063] Example 6

[0064] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 650℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 650℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 1mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier C.

[0065] Example 7

[0066] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 750℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 750℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 1mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier D.

[0067] Example 8

[0068] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 650℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 650℃ for 4h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 0.5mol / L, stir it at room temperature for 2h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier E.

[0069] Example 9

[0070] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 650℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 650℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 5mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier F.

[0071] Example 10

[0072] Weigh 20g of the CeO2-Al2O3 composite oxide carrier prepared in Example 3 and put it into a crucible, and then put it into the reaction chamber for hydrothermal treatment. First, heat it to 650℃ at a rate of 10℃ / min in an air atmosphere, and then keep it at 650℃ for 5h, and then naturally cool it to room temperature. On this basis, weigh a certain mass of the hydrothermally treated CeO2-Al2O3 carrier and put it into a three-necked flask, then gradually add a hydrochloric acid solution with a concentration of 10mol / L, stir it at room temperature for 1h, filter it, wash it three times with ethanol and deionized water, dry it at 120℃ for 6h, and calcine it at 550℃ for 4h to obtain the acid-treated carrier G.

[0073] Weigh 20 g of each of the A to G carriers obtained in the above examples, load the active components on the carriers to prepare the catalyst, and the specific method is as follows.

[0074] Embodiment 11

[0075] Based on the hydroprocessing catalyst, the raw materials were weighed, and the content of NiO in terms of oxide was 5wt% and the content of MoO3 was 15wt%. 1.95g of Ni(NO3)2·6H2O and 1.84g of (NH4)6Mo7O24 ·4H2O were dissolved with water, and then mixed to obtain impregnation solution; 6.21g of the carriers AG described in Examples 4-10 were weighed respectively, and the impregnation solution was dripped onto the surface of the carriers; dried for 12 hours in a dark environment, then dried at 60°C for 12 hours, and then dried at 120°C for 12 hours. Finally, they were placed in a muffle furnace, heated to 550°C at a rate of 1°C / min and kept warm for 4 hours, and NiMo / CeO2-Al2O3 hydroprocessing catalysts A1-G1 were obtained respectively.

[0076] In order to further explore the effect of changing the support material and the hydroxyl content on the support surface on the catalyst performance, three comparative examples were set up to control the content of the metal active components unchanged. The specific steps are as follows.

[0077] Comparative Example 1

[0078] The hydroprocessing catalyst based on CeO2-Al2O3 carrier H treated at 650°C was prepared in the following steps: the raw materials were weighed based on the catalyst, the content of NiO in terms of oxide was 5wt%, and the content of MoO3 was 15wt%. 1.95g of Ni(NO3)2·6H2O and 1.84g of (NH4)6Mo7O 24 ·4H2O were dissolved with water respectively, and then mixed to obtain an impregnation solution; 8.40g CeO2-Al2O3 carrier H was weighed, and the impregnation solution was dripped onto the carrier surface drop by drop; it was dried in the dark for 12h, then dried at 60℃ for 12h, and then dried at 120℃ for 12h. Finally, it was placed in a muffle furnace, heated to 550℃ at a rate of 1℃ / min and kept warm for 4h to obtain a hydrothermally treated NiMo / CeO2-Al2O3 hydrogenation catalyst H1.

[0079] Comparative Example 2

[0080] A hydroprocessing catalyst based on a CeO2-Al2O3 carrier treated with 1 mol / L hydrochloric acid solution but not subjected to hydrothermal treatment was prepared. CeO2-Al2O3 treated with 1 mol / L hydrochloric acid solution was selected as carrier I. The specific steps were as follows: Based on the catalyst, the content of NiO in terms of oxide was 5 wt%, and the content of MoO3 was 15 wt%. 1.95 g of Ni(NO3)2·6H2O and 1.84 g of (NH4)6Mo7O 24·4H2O were dissolved in water, and then mixed to obtain an impregnation solution; 8.40g CeO2-Al2O3 carrier I was weighed, and the impregnation solution was dripped onto the carrier surface; it was dried in the dark for 12h, then dried at 60℃ for 12h, and then dried at 120℃ for 12h. Finally, it was placed in a muffle furnace, heated to 550℃ at a rate of 1℃ / min and kept warm for 4h to obtain NiMo / CeO2-Al2O3 hydrogenation catalyst I1.

[0081] Comparative Example 3

[0082] The hydroprocessing catalyst based on CeO2-Al2O3 carrier J without hydrothermal treatment and acid treatment was prepared. The specific steps were as follows: the raw materials were weighed based on the catalyst, the content of NiO in terms of oxide was 5wt%, and the content of MoO3 was 15wt%. 1.95g of Ni(NO3)2·6H2O and 1.84g of (NH4)6Mo7O 24 ·4H2O were dissolved in water respectively, and then mixed to obtain an impregnation solution after dissolution; 8.40g of the CeO2-Al2O3 composite oxide support described in Example 3 was weighed, and the impregnation solution was added drop by drop onto the surface of the support; it was dried in a dark place for 12h, then dried at 60℃ for 12h, and then dried at 120℃ for 12h; finally, it was placed in a muffle furnace, heated to 550℃ at a rate of 1℃ / min and kept warm for 4h to obtain NiMo / CeO2-Al2O3 hydrogenation treatment catalyst J1.

[0083] Comparative Example 4

[0084] The hydroprocessing catalyst based on the untreated γ-alumina carrier K was prepared in the following steps: the raw materials were weighed based on the catalyst, the content of NiO in terms of oxide was 5wt%, and the content of MoO3 was 15wt%. 1.95g of Ni(NO3)2·6H2O and 1.84g of (NH4)6Mo7O 24 ·4H2O were dissolved in water respectively, and then mixed to obtain an impregnation solution after dissolution; 8.40g of γ-alumina carrier K was weighed, and the impregnation solution was added drop by drop onto the surface of the carrier; it was dried in a dark place for 12h, then dried at 60℃ for 12h, and then dried at 120℃ for 12h; finally, it was placed in a muffle furnace, heated to 550℃ at a rate of 1℃ / min and kept warm for 4h to obtain NiMo / γ-alumina hydrogenation treatment catalyst K1.

[0085] The titration method was used to determine the surface hydroxyl content of the above 12 carriers AK, and the specific steps are as follows.

[0086] Weigh 1g of sample and put it into a 100mL beaker, add 12mL of anhydrous ethanol, and then add 40mL of 20% NaCl solution. After shaking, add the prepared HCl to adjust the pH to 4, then slowly add NaOH solution to adjust the pH to about 9. After maintaining it for a certain period of time to stabilize, record the amount of NaOH solution added to different samples. Finally, according to the following formula: N = (C*V*N A ) / S*m to calculate the content of surface hydroxyl groups. The results of different embodiments are shown in Table 1.

[0087] Table 1 Determination results of hydroxyl content on the surface of different carriers

[0088]

[0089] It can be seen from the data in Table 1 that the method for regulating hydroxyl groups on the surface of an oxide carrier of the present invention can accurately regulate hydroxyl groups. First, by comparing Examples 4-7, it can be seen that by keeping the acid concentration unchanged during the acid treatment and adjusting different hydrothermal treatment temperatures, the hydroxyl content on the surface of the carrier shows a trend of decreasing with increasing temperature; by comparing Examples 6, 8-10, it can be seen that by keeping the hydrothermal treatment temperature unchanged and setting an increasing concentration gradient of the acid, the hydroxyl content on the surface of the carrier presents a "volcano-shaped curve", in which the hydroxyl content on the surface of the carrier is the highest when the acid concentration is 1 mol / L.

[0090] The 11 catalysts prepared above were subjected to a fixed-bed hydrogenation microreactor with low-quality diesel as the raw material (sulfur content 1650ug / g) under the following reaction conditions: temperature 340°C, pressure 4MPa, hydrogen-to-oil volume ratio 150, volume space velocity 20h -1 , the catalyst loading amount is 2mL, and the hydrodesulfurization ability of the catalyst is evaluated. Among them, the catalyst is pre-sulfurized before the hydrodesulfurization of diesel, and the sulfurization conditions are: temperature: 320℃, pressure: 4MPa, sulfurization time: 5h, hydrogen-oil ratio 100, volume space velocity 10h -1 .

[0091] After the hydrodesulfurization reaction, samples were taken for determination of sulfur content. The sulfur content in the generated oil was determined using a fluorescence sulfur analyzer (RPP-2000S), and the desulfurization rate was calculated and compared with the hydroxyl content of the carrier (results in Table 1). The results are listed in Table 2.

[0092] Table 2 Evaluation results of the hydrodesulfurization performance of the catalyst

[0093]

[0094]

[0095] It can be seen from the data in Table 2 that compared with the hydrodesulfurization catalyst prepared with carrier K, the hydrodesulfurization performance of the catalyst prepared with CeO2-Al2O3 carrier has been significantly improved. Secondly, it shows that the hydroxyl content has a significant effect on the desulfurization rate of inferior diesel. Hydrothermal treatment usually helps to form silicon hydroxyl (Si-OH) and cerium hydroxyl (Ce-OH), etc. These hydroxyl groups mainly participate in redox reactions, enhance the reactivity and stability of the catalyst, and can promote the conversion of sulfides; acid treatment usually promotes the formation of surface hydroxyl (H-OH), which mainly contributes to the acid sites of the catalyst, but too many acid sites may affect the selectivity and stability of the catalyst, resulting in excessively intense reactions or increased side reactions, affecting the acid catalytic performance of the catalyst. From Figure 2 It can be seen that the catalysts obtained at different hydrothermal treatment temperatures have different performances. As the hydrothermal temperature increases, the catalytic performance first increases and then decreases. Although the hydroxyl content of catalysts I1 and J1 is higher than that of catalyst G1, their hydroxyl types and surface acidity and alkalinity may be different from those of catalyst G1. Catalysts I1 and J1 may contain more hydroxyl groups or other acidic sites, while catalyst G1 may contain more silicon hydroxyl groups and cerium hydroxyl groups, which may be more effective in hydrodesulfurization, resulting in the desulfurization performance of catalyst G1 being better than that of catalysts I1 and J1. Comparison of catalyst H1 with other embodiments: Although catalyst H1 has a higher hydroxyl content, the types and distribution of hydroxyl groups on its surface may not be ideal. Catalyst H1 may contain more hydroxyl groups, and the excessive number of these acidic sites may cause it to perform worse than other catalysts (such as D1, F1, G1) during the desulfurization process. The latter may retain more silicon hydroxyl groups and cerium hydroxyl groups on the surface, improving the hydrodesulfurization performance of the catalyst. Among them, the hydrotreating catalyst prepared by carrier C has the highest desulfurization rate for inferior diesel, and the sulfur content can reach 6.69ug·g -1 , showing excellent hydrodesulfurization performance, indicating that the appropriate hydroxyl content may be an important reason for improving the activity of the catalyst and showing better overall performance in complex reactions.

[0096] Figure 3 HRTEM images of the sulfided NiMo / CeO2-Al2O3 catalysts prepared in Examples 4 to 7 of the present invention. The statistical details of the HRTEM results are shown in Table 3.

[0097] Table 3 Statistical details of HRTEM results for the catalyst series of Examples 4-7

[0098]

[0099]

[0100] Note: is the length of MoS2 flakes, is the stacking number of MoS2 lamellae, D Mo It is the number of edge Mo atoms calculated based on the length of the MoS2 lamellae.

[0101] The results in Table 3 also show that with the increase of calcination temperature, the presence of CeO2 reduces the metal-support interaction (MSI) and enhances the surface acidity, resulting in an increase in the number of MoS2 platelets promoted by Ni. and length The results show that the directional hydrogenation of complex sulfides meets the requirements of the hydroprocessing catalyst active phase geometry and electronic structure to create high stacking and short platelet atomic wafers. On the contrary, further increasing the temperature will lead to a significant decrease in the hydroxyl content. In addition, compared with the NiMo / γ-Al2O3 catalyst (the traditional γ-Al2O3 exhibits low stacking and long platelets), the NiMo / CeO2-Al2O3 catalyst series has a higher number of stacking layers and a shorter MoS2 length, which is conducive to the formation of more angular active sites, thus having better catalytic activity. These results once again show that the appropriate CeO2 content and the appropriate hydroxyl content can promote the stacking of MoS2 platelets and further enhance the formation of type II NiMoS active phase.

Claims

1. A method for preparing a hydrodesulfurization catalyst, characterized in that: The following steps are involved: S1, dissolving the aluminum source in ethanol, adding acid dropwise, stirring, and obtaining solution A; dissolving the template in ethanol, stirring, and obtaining solution B; adding solution A dropwise to solution B, stirring, adding cerium source, stirring, aging, and calcining to obtain a CeO2-Al2O3 composite oxide carrier; S2, subjecting the CeO2-Al2O3 composite oxide support to hydrothermal treatment and then acid treatment to obtain a hydroxyl-regulated CeO2-Al2O3 support; S3, dissolving the precursor of the active component in water to obtain an impregnation solution; dropping the impregnation solution onto the surface of the hydroxyl-regulated CeO2-Al2O3 carrier, and then drying and calcining to obtain a hydrodesulfurization catalyst; wherein the active component includes Group VIB metals and Group VIII metals.

2. The method for preparing a hydrodesulfurization catalyst according to claim 1, characterized in that: In S1, the molar ratio of the aluminum source to the cerium source is (1-20):

1.

3. The method for preparing a hydrodesulfurization catalyst according to claim 1, characterized in that: In S2, the CeO2-Al2O3 composite oxide support is subjected to hydrothermal treatment. The specific method is: the CeO2-Al2O3 composite oxide support is placed in a container, air containing H2O is introduced, the temperature is raised to 400-800°C, and the temperature is kept for 3-6 hours. After the treatment, the CeO2-Al2O3 composite oxide support is naturally cooled to room temperature.

4. The method for preparing a hydrodesulfurization catalyst according to claim 1, characterized in that: In S2, the acid treatment specifically comprises: adding an acid solution to the CeO2-Al2O3 composite oxide support after hydrothermal treatment, stirring, and then filtering, washing, drying, and calcining to obtain a hydroxyl-regulated CeO2-Al2O3 support.

5. The method for preparing a hydrodesulfurization catalyst according to claim 4, characterized in that: In S3, the Group VIB metal is molybdenum or tungsten, and the Group VIII metal is nickel or cobalt.

6. The method for preparing a hydrodesulfurization catalyst according to claim 5, characterized in that: The Group VI B metal is molybdenum, and the Group VIII metal is nickel; the precursor of the active component includes a molybdenum-containing compound and a nickel-containing compound; wherein the molybdenum-containing compound is at least one of molybdenum oxide, molybdate and paramolybdate; and the nickel-containing compound is at least one of nickel nitrate, nickel acetate, basic nickel carbonate and nickel chloride.

7. The method for preparing a hydrodesulfurization catalyst according to claim 6, characterized in that: In S3, the calcination temperature is 300-900°C, and the calcination time is 4-8h.

8. A hydrodesulfurization catalyst obtained by the preparation method according to any one of claims 1 to 7.

9. The hydrodesulfurization catalyst according to claim 8, characterized in that Based on the total mass of the hydrodesulfurization catalyst, the content of the Group VIB metal component in terms of oxide is 0.5 wt% to 15 wt%, and the content of the Group VIII metal component is 5 wt% to 30 wt%.

10. Use of the hydrodesulfurization catalyst according to claim 8 in diesel hydrodesulfurization.

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