Selective hydrogenation catalyst and preparation method thereof

Abstract

The invention discloses a selective hydrogenation catalyst and a preparation method thereof. The catalyst comprises hydrogenation active components and a carrier, the hydrogenation active components comprise molybdenum and nickel, on the basis of the weight of the catalyst, the content of molybdenum in terms of oxide is 3.0-11.0%, the content of nickel in terms of oxide is 9.0-18.0%, and the Ni / Mo atom molar ratio is 3.1-11.5; the content of the carrier is 71%-88%, and the hydrogenation catalyst carrier comprises aluminum oxide and calcium phosphate. The preparation method comprises the following steps: adding calcium oxide into bottom water of a reactor, adding an aluminum salt solution and a precipitant in a parallel flow manner, carrying out a gelling reaction, then adding phosphoric acid, carrying out an aging reaction, and washing, filtering and drying an aging product to obtain modified alumina dry glue powder; molding the modified alumina dry glue powder to prepare a hydrogenation catalyst carrier; and then loading an active component to obtain the selective hydrogenation catalyst. The catalyst provided by the invention has high hydrogenation activity and selectivity when being applied to a gasoline selective hydrodesulfurization process by adjusting the proportion of the active components and well matching the active components with the catalyst carrier.

Description

Technical Field

[0001] The invention belongs to the technical field of clean oil refining, and specifically relates to a selective hydrogenation catalyst and a preparation method thereof. Background Art

[0002] Among all gasoline components, catalytic cracking gasoline has high sulfur and olefin content, which is the main obstacle to gasoline quality upgrading. To achieve gasoline product quality upgrading, it is necessary to realize that the catalytic gasoline hydrodesulfurization unit can achieve desulfurization and olefin reduction while ensuring the minimum octane loss. Traditional desulfurization technology saturates high-octane olefin components to produce low-octane alkanes, resulting in a significant decrease in octane number. In order to achieve the dual goals of deep desulfurization of FCC gasoline and minimize octane loss, different processes and catalysts are used at home and abroad to achieve this goal. IFP Prime-G + The technology consists of a selective hydrogenation unit (SHU), a fractionation tower (to separate LCN from MCN or HCN), and a dual catalyst hydrogenation unit for processing MCN and HCN. The process uses the full fraction of FCC gasoline as feedstock and performs hydrogenation pretreatment in the selective hydrogenation unit to hydrogenate and saturate the dienes and isomerize the double bonds; small molecular mercaptans and sulfides are converted into large molecular sulfides. Then, the gasoline is separated into olefin-rich light gasoline and sulfur-rich heavy gasoline through fractionation; the sulfur-rich heavy gasoline is then subjected to selective deep hydrogenation and desulfurization using a dual catalyst to minimize olefin saturation and obtain minimized octane number loss. The core of this technical route is the selective hydrogenation catalyst for hydrogenation pretreatment in the selective hydrogenation unit.

[0003] CN101024779B discloses a selective hydrogenation method using a sulfurized catalyst, which can selectively hydrogenate polyunsaturated compounds in gasoline into monounsaturated compounds, and convert light sulfur-containing compounds into heavier compounds by reacting with unsaturated compounds. CN101016479B discloses a selective hydrogenation method using a catalyst with controlled porosity, which can jointly implement the selective hydrogenation of polyunsaturated compounds in gasoline into monounsaturated compounds, and convert light sulfur-containing compounds into heavier compounds by reacting with unsaturated compounds. CN101205483B discloses a selective hydrogenation method using a catalyst with a specific carrier, which can simultaneously implement the selective hydrogenation of polyunsaturated compounds in gasoline into monounsaturated compounds, and weight light sulfur-containing compounds by reacting with these unsaturated compounds. CN106867575A discloses a selective hydrogenation method using a sulfurized catalyst with a specified composition, which involves a method for combining polyunsaturated compounds and weighting light sulfur-containing compounds by reacting with unsaturated compounds. A large number of studies have shown that the activity of converting light sulfur compounds into heavier compounds can be effectively improved by adjusting the content of active components and thus adjusting the atomic ratio of active component metals. In addition to the metal active components, the properties of the Al2O3 carrier (such as surface acidity, etc.) also have an important influence on the performance of supported metal sulfide catalysts. Both the metal components of the above-mentioned patented catalyst and the Al2O3 carrier need to be further improved and enhanced. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a selective hydrogenation catalyst and a preparation method thereof. The catalyst of the present invention has high hydrogenation activity and selectivity when applied to the selective hydrogenation desulfurization process of gasoline by adjusting the ratio of active components and the good matching of the catalyst carrier.

[0005] The selective hydrogenation catalyst of the present invention comprises a hydrogenation active component and a hydrogenation catalyst carrier. The hydrogenation active component is molybdenum and nickel. Based on the weight of the catalyst, the molybdenum content in terms of oxide is 3.0-11.0%, preferably 4.0-9.0%, the nickel content in terms of oxide is 9.0-18.0%, preferably 11.0-16.0%, and the Ni / Mo atomic molar ratio is 3.1-11.5, preferably 3.4-7.6; the hydrogenation catalyst carrier has a molybdenum content of 71%-88%, and the hydrogenation catalyst carrier comprises aluminum oxide and calcium phosphate.

[0006] In the selective hydrogenation catalyst of the present invention, the hydrogenation catalyst carrier has a calcium phosphate content of 2.5% to 18.0%, preferably 5.0% to 16.0%, and an alumina content of 82.0% to 97.5%, preferably 84.0% to 95.0%, based on the weight of the carrier; the total acid content of the carrier infrared acid is 0.45 to 0.75 mmol / g, preferably 0.50 to 0.70 mmol / g, the acid content of L acid is 0.40 to 0.70 mmol / g, preferably 0.35 to 0.65, and the ratio of B acid to L acid is 0.07 to 0.25, preferably 0.08 to 0.20.

[0007] The selective hydrogenation catalyst of the present invention has a pore volume of 0.45 to 1.30 mL / g and a specific surface area of ​​180 to 400 m 2 / g.

[0008] The selective hydrogenation catalyst of the present invention may also include additives such as Ti, Zr, V, Cu, Zn, Si, etc., and the content of the additives is 0.5% to 7% based on the total weight of the catalyst, and the sum of the contents of the catalyst components is 100%.

[0009] The preparation method of the selective hydrogenation catalyst of the present invention comprises the following contents:

[0010] (1) adding calcium oxide to the bottom water of the reactor, and then adding aluminum salt solution and a precipitant in parallel to carry out neutralization and gelation reaction, adding phosphoric acid after the gelation is completed to carry out aging reaction, and washing, filtering and drying the aging product to obtain modified alumina dry gel powder;

[0011] (2) uniformly mixing the modified alumina dry glue powder, the peptizing agent and the extrusion aid, extruding into strips, and drying and calcining to obtain a hydrogenation catalyst carrier;

[0012] (3) The active components are loaded onto a hydrogenation catalyst carrier according to the atomic molar ratio of Mo and Ni to obtain a selective hydrogenation catalyst.

[0013] In the method of the present invention, the temperature of the bottom water in step (1) is 50-90°C.

[0014] In the method of the present invention, the aluminum salt solution in step (1) is an aluminum sulfate aqueous solution, with an aluminum oxide concentration of 4 g / 100 mL to 12 g / 100 mL; and the precipitant is a sodium aluminate aqueous solution, with an aluminum oxide concentration of 12 g / 100 mL to 40 g / 100 mL.

[0015] In the method of the present invention, the gelling reaction conditions in step (1) are: time of 0.4 to 1.5 hours and pH value of 7.0 to 9.5.

[0016] In the method of the present invention, the amount of phosphoric acid added in step (1) is such that all calcium sulfate in the gelled product is converted into calcium phosphate, and is generally 1.6% to 12% of the weight of the aluminum oxide in the gelled product.

[0017] In the method of the present invention, the aging reaction time in step (1) is 0.2 to 1 hour.

[0018] In the method of the present invention, the washing in step (1) is generally performed with deionized water for 2 to 5 times until SO4 2- ≯2.5%, Na + ≯0.05%,Fe 3+ ≯0.25%.

[0019] In the method of the present invention, the drying conditions in step (1) are: drying temperature of 90 to 130° C., and drying time of 5 to 34 hours.

[0020] In the method of the present invention, the extrusion aid described in step (2) can be one or more of sesbania powder, cellulose, starch, high molecular surfactant, etc., and the amount used accounts for 0.1% to 20.0% of the dry basis weight of the phosphorus and calcium-containing aluminum oxide dry glue powder in step (1); the peptizing agent can be one or more of aluminum sulfate, citric acid, nitric acid, acetic acid, oxalic acid, etc., and the amount used accounts for 0.1% to 20.0% of the dry basis weight of the modified aluminum oxide dry glue powder in step (1).

[0021] In the method of the present invention, the drying and calcining conditions in step (2) are as follows: drying at 100-120° C. for 1-5 hours, and calcining at 400-750° C. for 1-5 hours.

[0022] In the method of the present invention, the loading method described in step (3) is generally an impregnation method, followed by drying and calcination. The drying and calcination conditions are as follows: drying at 100-120°C for 1-5 hours and calcining at 350-550°C for 1-5 hours.

[0023] The hydrogenation catalyst carrier of the present invention is an aluminum oxide carrier containing phosphorus and calcium. A neutralization reaction of aluminum oxide is carried out in an environment where calcium oxide undergoes a hydration reaction and releases heat. Calcium hydroxide formed by the hydration reaction of calcium oxide is present in the neutralization reaction solution as a neutralization reaction seed. Calcium sulfate precipitation is simultaneously generated during the formation of aluminum oxide dry gel. After the neutralization is completed, phosphoric acid is added for aging. The calcium sulfate is converted into calcium phosphate. At the same time, the total acid content of the carrier, especially the L acid content, is greatly increased to form a sulfur-philic carrier with an L acid center, which can improve the hydrogenation capacity of the catalyst. The catalyst prepared by the method of the present invention can form a stable structure with aluminum oxide by adding calcium components in the form of seeds during the aluminum oxide neutralization process. Phosphoric acid is added before aging to adjust the acid properties and complete the conversion of calcium sulfate into calcium phosphate. After aging, the calcium and phosphorus components can still form a stable structure with aluminum oxide. The presence of calcium phosphate is beneficial to inhibiting the formation of NiAl2O4 phase and increasing Ni 2+ The number of ions can effectively adjust the ratio of active metal atoms, change the dispersion state of active components on the alumina surface, form more oligomeric Mo species, thereby increasing the MoS2 active phase, inhibiting the carbon deposition reaction of the catalyst, and enhancing the performance of converting small molecular thiols and sulfides into large molecular sulfides.

[0024] The selective hydrogenation catalyst of the present invention can be used in a gasoline selective hydrodesulfurization process, in which the whole fraction of FCC gasoline is fed as feedstock, and the catalyst of the present invention is used for hydrogenation pretreatment in a selective hydrogenation unit to hydrogenate and saturate diolefins and isomerize double bonds; small molecular mercaptans and sulfides are converted into macromolecular sulfides. Then, gasoline is separated into olefin-rich light gasoline and sulfur-rich heavy gasoline by fractionation; the sulfur-rich heavy gasoline is then subjected to selective deep hydrodesulfurization with a selective hydrodesulfurization catalyst, and minimized octane number loss is obtained by minimizing olefin saturation. DETAILED DESCRIPTION

[0025] In the present invention, the specific surface area and pore volume are determined by low temperature liquid nitrogen adsorption method, and the total acid content, B acid content and L acid content of infrared acid are determined by pyridine infrared adsorption spectroscopy. In the present invention, % represents mass percentage. The catalyst composition determination method is determined by colorimetry.

[0026] The specific preparation process of the catalyst of the present invention is as follows:

[0027] Alumina dry glue powder, peptizing agent and extrusion aid are mixed, mixed evenly, extruded on an extruder, and then dried at 100-120°C for 1-5 hours, and then heated to 400-750°C at a heating rate of 150-250°C / hour for 1-5 hours to obtain a catalyst carrier. After that, the alumina carrier is placed in a rolling pot, and Mo and Ni solutions of the saturated water absorption of the carrier are sprayed into the alumina carrier in the rolling pot in an atomized manner under rotating conditions. After the solution is sprayed, the rolling pot is continued to rotate for 10-60 minutes, and then placed for 1-24 hours, dried at 100-120°C for 1-5 hours, and then heated to 350-550°C at a heating rate of 150-250°C / hour for 1-5 hours to obtain a finished catalyst.

[0028] In the above preparation method, the concentration of the impregnating solution is determined by the water absorption rate and the desired catalyst composition (content).

[0029] The catalyst used in the present invention is specifically described below with reference to examples.

[0030] Example 1

[0031] First add 4.2g of calcium oxide to 1L of water, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80°C for 1.0h, control the pH value of the neutralization reaction to be 8.8-9.0, then add 4.9g of phosphoric acid, age for 0.5h, wash and filter twice to obtain a filter cake, dry it at 110°C for 24h, and grind it to obtain alumina dry rubber powder; the dry rubber powder is extruded into strips, then dried at 110°C for 3 hours, and calcined at 600°C for 3 hours to obtain an alumina carrier.

[0032] Place 200g of alumina carrier in a spray drum, and spray 156mL of a solution containing 10.5g of molybdenum trioxide and 67.9g of nickel nitrate into the alumina carrier in a rotating manner. After the solution is sprayed, continue to rotate in the drum for 30 minutes, then place it for 18 hours, dry it at 110°C for 3 hours, and then heat it to 500°C at a heating rate of 200°C / hour and calcine it for 3 hours to obtain a finished catalyst A.

[0033] Example 2

[0034] First add 7g of calcium oxide to 1L of water, and neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80°C for 1.0h, control the pH value of the neutralization reaction to be 8.8-9.0, then add 8.17g of phosphoric acid, age for 0.5h, wash and filter twice to obtain a filter cake, dry it at 110°C for 24h, and grind it to obtain alumina dry rubber powder; the dry rubber powder is formed into strips by extrusion, and then dried at 110°C for 3 hours, and calcined at 600°C for 3 hours to obtain an alumina carrier.

[0035] Place 200g of alumina carrier in a spray drum, and spray 170mL of a solution containing 10.8g of molybdenum trioxide and 70.3g of nickel nitrate into the alumina carrier in a rotating manner. After the solution is sprayed, continue to rotate in the drum for 30 minutes, then place it for 18 hours, dry it at 110°C for 3 hours, and then heat it to 500°C at a heating rate of 200°C / hour and calcine it for 3 hours to obtain the finished catalyst B.

[0036] Example 3

[0037] First add 4.2g of calcium oxide to 1L of water, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80°C for 1.0h, control the pH value of the neutralization reaction to be 8.8-9.0, then add 4.9g of phosphoric acid, age for 0.5h, wash and filter twice to obtain a filter cake, dry it at 110°C for 24h, and grind it to obtain alumina dry rubber powder; the dry rubber powder is extruded into strips, then dried at 110°C for 3 hours, and calcined at 600°C for 3 hours to obtain an alumina carrier.

[0038] Place 200 g of alumina carrier in a spray drum, and spray 156 mL of a solution containing 24.2 g of molybdenum trioxide and 84.6 g of nickel nitrate into the alumina carrier in a rotating manner. After the solution is sprayed, continue to rotate in the drum for 30 minutes, then place it for 18 hours, dry it at 110°C for 3 hours, and then heat it to 500°C at a heating rate of 200°C / hour and calcine it for 3 hours to obtain a finished catalyst C.

[0039] Example 4

[0040] First add 7g of calcium oxide to 1L of water, and neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80°C for 1.0h, control the pH value of the neutralization reaction to be 8.8-9.0, then add 8.17g of phosphoric acid, age for 0.5h, wash and filter twice to obtain a filter cake, dry it at 110°C for 24h, and grind it to obtain alumina dry rubber powder; the dry rubber powder is formed into strips by extrusion, and then dried at 110°C for 3 hours, and calcined at 600°C for 3 hours to obtain an alumina carrier.

[0041] 200 g of alumina carrier was placed in a spray drum. Under rotating conditions, 155 mL of a solution containing 21.9 g of molybdenum trioxide and 80.0 g of nickel nitrate was sprayed into the alumina carrier in the drum in an atomized manner. After the solution was sprayed, the drum was continuously rotated for 30 minutes, and then placed for 18 hours. The drum was dried at 110°C for 3 hours, and then heated to 500°C at a rate of 200°C / hour and calcined for 3 hours to obtain a finished catalyst D.

[0042] Comparative Example 1

[0043] Catalyst E was prepared in the same manner as in Example 1, except that calcium oxide and phosphoric acid were not added.

[0044] Comparative Example 2

[0045] Catalyst F was prepared in the same manner as in Example 3, except that calcium oxide and phosphoric acid were not added.

[0046] Comparative Example 3

[0047] Catalyst G was prepared in the same manner as in Example 1, except that phosphoric acid was not added.

[0048] Comparative Example 4

[0049] Catalyst H was prepared in the same manner as in Example 3, except that calcium oxide was not added.

[0050] Comparative Example 5

[0051] Catalyst I was prepared by the same method as in Example 1, except that 200 g of an alumina carrier was placed in a spray drum. Under rotating conditions, 156 mL of a solution containing 32.8 g of molybdenum trioxide and 94.4 g of nickel nitrate was sprayed into the alumina carrier in the drum in an atomized manner. After the solution was sprayed, the drum was rotated for 30 minutes, then allowed to stand for 18 hours, dried at 110°C for 3 hours, and then heated to 500°C at a rate of 200°C / hour for calcination for 3 hours.

[0052] Example 6

[0053] This example shows the physicochemical properties of the catalysts prepared in the above examples and the comparative results of the above examples after 600 hours of operation on a small-scale hydrogenation unit, see Tables 1 and 2.

[0054] Table 1 Main properties of catalysts

[0055]

[0056]

[0057] Table 2 Catalyst selective hydrogenation activity

[0058]

[0059] Note: Reaction conditions: P = 2.3MPa; LHSV = 4.9h -1 ; H2 / Oil=9.7Nm 3 / m 3 ; Reaction temperature = 150°C.

[0060] Table 2 lists the test results of the selective hydrogenation reaction, which show that the content of dienes in the full-fraction gasoline using the catalyst of the present invention is significantly reduced, and the olefins are slightly saturated. The comparison results of the sulfur structures of the raw materials and the reaction products (mercaptans and sulfides) show that the mercaptan sulfur and sulfide in the light component are completely converted, and the contents of C6 mercaptan, C6 sulfide, C7, and C8 sulfide in the heavy component are all increased, indicating the conversion of mercaptan sulfur and sulfide in the light component to the heavy component. The catalyst of the present invention has good selective hydrogenation reaction performance for removing dienes and mercaptan sulfur.

Claims

1. A selective hydrogenation catalyst, characterized in that: The catalyst comprises a hydrogenation active component and a hydrogenation catalyst carrier, wherein the hydrogenation active component is molybdenum and nickel, and based on the weight of the catalyst, the molybdenum content in terms of oxide is 3.0-11.0%, preferably 4.0-9.0%, the nickel content in terms of oxide is 9.0-18.0%, preferably 11.0-16.0%, and the Ni / Mo atomic molar ratio is 3.1-11.5, preferably 3.4-7.6; the hydrogenation catalyst carrier has a content of 71%-88%, and the hydrogenation catalyst carrier comprises aluminum oxide and calcium phosphate.

2. The catalyst according to claim 1, characterized in that: Based on the weight of the carrier, the calcium phosphate content is 2.5%~18.0%, preferably 5.0%~16.0%, the aluminum oxide content is 82.0%~97.5%, preferably 84.0%~95.0%; the total acid content of the carrier infrared acid is 0.45~0.75mmol / g, preferably 0.50~0.70mmol / g, the L acid content is 0.40~0.70mmol / g, preferably 0.35~0.65, and the B acid / L acid ratio is 0.07~0.25, preferably 0.08~0.

20.

3. The catalyst according to claim 1, characterized in that: The pore volume is 0.45~1.30mL / g, and the specific surface area is 180~400m 2 / g.

4. The catalyst according to claim 1, characterized in that: The catalyst includes additives such as Ti, Zr, V, Cu, Zn, Si, etc. The content of the additives is 0.5% to 7% based on the total weight of the catalyst, and the sum of the contents of the various components of the catalyst is 100%.

5. A method for preparing the selective hydrogenation catalyst according to any one of claims 1 to 4, characterized in that The method comprises the following contents: (1) adding calcium oxide to the bottom water of the reactor, and then adding aluminum salt solution and precipitant in parallel to carry out neutralization and gelling reaction, adding phosphoric acid after gelling to carry out aging reaction, washing, filtering and drying the aged product to obtain modified alumina dry gel powder; (2) uniformly mixing the modified alumina dry gel powder, gelling agent and extrusion aid, extruding into strips, drying and calcining to obtain a hydrogenation catalyst carrier; (3) loading the active components onto the hydrogenation catalyst carrier according to the atomic molar ratio of Mo and Ni to obtain a selective hydrogenation catalyst.

6. The method according to claim 5, characterized in that: The temperature of the bottom water in step (1) is 50-90°C.

7. The method according to claim 5, characterized in that: The aluminum salt solution in step (1) is an aluminum sulfate aqueous solution, with an aluminum oxide concentration of 12 g / 100 to 40 g / 100 mL; the precipitant is a sodium aluminate aqueous solution, with an aluminum oxide concentration of 4 g / 100 to 12 g / 100 mL.

8. The method according to claim 5, characterized in that: The gelling reaction conditions in step (1) are: time of 0.4 to 1.5 hours and pH value of 7.0 to 9.

5.

9. The method according to claim 5, characterized in that: The aging reaction time in step (1) is 0.2 to 1 hour.

10. The method according to claim 5, characterized in that: The washing in step (1) is performed with deionized water for 2 to 5 times until SO4 2- ≯2.5%, Na + ≯0.05%,Fe 3+ ≯0.25%.

11. The method according to claim 5, characterized in that: The drying conditions in step (1) are: drying temperature 90-130° C., and drying time 5-34 hours.

12. The method according to claim 5, characterized in that: The extrusion aid in step (2) is one or more of sesbania powder, cellulose, starch, and polymer surfactant, and its usage accounts for 0.1% to 20.0% of the dry weight of the modified alumina dry glue powder in step (1); the peptizing agent is one or more of aluminum sulfate, citric acid, nitric acid, acetic acid, and oxalic acid, and its usage accounts for 0.1% to 20.0% of the dry weight of the modified alumina dry glue powder in step (1).

13. The method according to claim 5, characterized in that: The drying and calcining conditions in step (2) are as follows: drying at 100-120°C for 1-5 hours and calcining at 400-750°C for 1-5 hours.

14. The method according to claim 5, characterized in that: The loading method in step (3) is an impregnation method, followed by drying and calcination. The drying and calcination conditions are as follows: drying at 100-120°C for 1-5 hours, and calcination at 350-550°C for 1-5 hours.

15. Use of the selective hydrogenation catalyst according to any one of claims 1 to 4 in a gasoline selective hydrodesulfurization process.

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