A selective hydrogenation catalyst and its preparation method

Abstract

This invention discloses a selective hydrogenation catalyst and its preparation method. The catalyst comprises a hydrogenation active component and a support. The hydrogenation active component is molybdenum and nickel, with a molybdenum content of 3.0-11.0% and a nickel content of 9.0-18.0% (based on the weight of the catalyst oxide), and a Ni / Mo atomic molar ratio of 3.1-11.5. The support content is 71%-88%, and the hydrogenation catalyst support comprises alumina and calcium phosphate. The preparation method includes: adding calcium oxide to the bottom water of a reactor, and simultaneously adding an aluminum salt solution and a precipitant to carry out a gelling reaction, followed by adding phosphoric acid for an aging reaction. The aging product is washed, filtered, and dried to obtain modified alumina dry gel powder; the modified alumina dry gel powder is shaped to prepare a hydrogenation catalyst support; and then the active component is loaded to obtain the selective hydrogenation catalyst. By adjusting the ratio of the active component to the catalyst support, the catalyst of this invention exhibits high hydrogenation activity and selectivity in the selective hydrogenation desulfurization process of gasoline.

Description

Technical Field

[0001] This invention belongs to the field of clean refining technology, specifically relating to a selective hydrogenation catalyst and its preparation method. Background Technology

[0002] Among all gasoline components, catalytic cracking gasoline has high sulfur and olefin content, posing a major obstacle to gasoline quality upgrades. To achieve gasoline product quality upgrades, catalytic gasoline hydrodesulfurization units must ensure minimal octane number loss while simultaneously desulfurizing and reducing olefins. Traditional desulfurization technologies saturate high-octane olefin components, generating low-octane alkanes, resulting in a significant decrease in octane number. To achieve the dual goals of deep desulfurization of FCC gasoline and minimal octane number loss, different processes and catalysts are employed both domestically and internationally. IFP's Prime-G... + The technology consists of a selective hydrotreating unit (SHU), a fractionation tower (to separate LCN from MCN or HCN), and a dual-catalyst hydrotreating unit for processing both MCN and HCN. The process uses FCC gasoline full-fraction feed, undergoing hydrotreating pretreatment in the SHU unit to hydrogenate and saturate dienes and isomerize double bonds; small-molecule thiols and sulfides are converted into large-molecule sulfides. Then, fractionation separates the gasoline into olefin-rich light gasoline and sulfur-rich heavy gasoline; the sulfur-rich heavy gasoline is then subjected to selective deep hydrodesulfurization using a dual-catalyst, minimizing olefin saturation and thus minimizing octane number loss. The core of this technology is the selective hydrotreating catalyst used in the hydrotreating pretreatment within the SHU unit.

[0003] CN101024779B discloses a selective hydrogenation method using a sulfurization catalyst, which can selectively hydrogenate polyunsaturated compounds in gasoline into monounsaturated compounds, and convert light sulfur-containing compounds into heavier compounds through reaction with unsaturated compounds. CN101016479B discloses a selective hydrogenation method using a catalyst with controlled porosity, which can simultaneously perform the selective hydrogenation of polyunsaturated compounds in gasoline into monounsaturated compounds, and the conversion of light sulfur-containing compounds into heavier compounds through reaction with unsaturated compounds. CN101205483B discloses a selective hydrogenation method using a catalyst with a specific support, which can simultaneously perform the selective hydrogenation of polyunsaturated compounds in gasoline into monounsaturated compounds, and the weighting of light sulfur-containing compounds through reaction with these unsaturated compounds. CN106867575A discloses a selective hydrogenation method using a sulfurization catalyst with a defined composition, which relates to a method for combining polyunsaturated compounds and increasing the weight of light sulfur-containing compounds through reaction with unsaturated compounds. Numerous studies have shown that adjusting the atomic ratio of the active metal component by modifying its content can effectively improve the conversion activity of light sulfur compounds into heavier compounds. Besides the metal active component, the properties of the Al₂O₃ support (such as surface acidity) also significantly influence the performance of supported metal sulfide catalysts. Both the metal component and the Al₂O₃ support of the aforementioned patented catalysts require further improvement and enhancement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a selective hydrogenation catalyst and its preparation method. By adjusting the ratio of the active components to achieve a good match with the catalyst support, the catalyst of this invention exhibits high hydrogenation activity and selectivity when applied to the selective hydrodesulfurization process of gasoline.

[0005] The selective hydrogenation catalyst of the present invention comprises a hydrogenation active component and a hydrogenation catalyst support. The hydrogenation active component is molybdenum and nickel, wherein, based on the weight of the catalyst, the molybdenum content (calculated as oxides) is 3.0–11.0%, preferably 4.0–9.0%, and the nickel content (calculated as oxides) 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 support content is 71%–88%, and the hydrogenation catalyst support comprises alumina and calcium phosphate.

[0006] In the selective hydrogenation catalyst of the present invention, the hydrogenation catalyst support, based on the weight of the support, 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%; the total acid content of the support is 0.45 to 0.75 mmol / g, preferably 0.50 to 0.70 mmol / g, the L acid content is 0.40 to 0.70 mmol / g, preferably 0.35 to 0.65, and the Brønsted acid / L acid ratio is 0.07 to 0.25, preferably 0.08 to 0.20.

[0007] The selective hydrogenation catalyst of this invention has a pore volume of 0.45–1.30 mL / g and a specific surface area of ​​180–400 m². 2 / g.

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

[0009] The method for preparing the selective hydrogenation catalyst of the present invention includes the following steps:

[0010] (1) Add calcium oxide to the bottom water of the reactor, and then add aluminum salt solution and precipitant in parallel to carry out neutralization and gelation reaction. After gelation, add phosphoric acid to carry out aging reaction. The aging product is washed, filtered and dried to obtain modified alumina dry glue powder.

[0011] (2) The modified alumina dry adhesive powder, adhesive solvent and extrusion aid are mixed evenly, extruded into strips, and dried and calcined to obtain the hydrogenation catalyst support;

[0012] (3) The active components are loaded onto the hydrogenation catalyst support 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 aqueous solution of aluminum sulfate, with an aluminum oxide concentration of 4 g / 100 mL to 12 g / 100 mL; the precipitant is an aqueous solution of sodium aluminate, with an aluminum oxide concentration of 12 g / 100 mL to 40 g / 100 mL.

[0015] In the method of the present invention, the gelation 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) to convert all the calcium sulfate in the gelling product into calcium phosphate is generally 1.6% to 12% of the weight of alumina in the gelling 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 this invention, the washing in step (1) generally involves washing with deionized water 2 to 5 times until SO4 is reached. 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 90-130℃, drying time 5-34 hours.

[0020] In the method of the present invention, the extrusion aid in step (2) can be one or more of guar gum powder, cellulose, starch, and polymeric surfactant, and the amount used is 0.1% to 20.0% of the dry basis weight of the phosphorus and calcium-containing alumina dry adhesive powder in step (1); the adhesive solvent can be one or more of aluminum sulfate, citric acid, nitric acid, acetic acid, and oxalic acid, and the amount used is 0.1% to 20.0% of the dry basis weight of the modified alumina dry adhesive powder in step (1).

[0021] In the method of the present invention, the drying and calcination 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 impregnation. After impregnation, the material is dried and calcined. 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 support of this invention is an alumina support containing phosphorus and calcium. The neutralization reaction of alumina is carried out in an environment where calcium oxide undergoes a hydration reaction and is exothermic. Calcium hydroxide formed from the calcium oxide hydration reaction exists as a seed crystal in the neutralization reaction solution. During the formation of the alumina dry gel, calcium sulfate precipitate is simultaneously generated. After neutralization, phosphoric acid is added for aging, converting calcium sulfate to calcium phosphate. Simultaneously, the total acidity of the support, especially the L-acid content, is significantly increased, forming a thiophilic support with L-acid centers, which can improve the hydrogenation capacity of the catalyst. The catalyst prepared by this invention allows the addition of calcium components in the form of seed crystals during alumina neutralization to form a stable structure with alumina. The addition of phosphoric acid before aging modifies the acidity and completes the conversion of calcium sulfate to calcium phosphate. After aging, the calcium and phosphorus components can still form a stable structure with alumina. The presence of calcium phosphate helps to suppress the formation of the NiAl2O4 phase and increase 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 improving the active phase of MoS2, inhibiting the carbon deposition reaction of the catalyst, and enhancing the performance of converting small molecule thiols and sulfides into large molecule sulfides.

[0024] The selective hydrotreating catalyst of this invention can be used in the selective hydrodesulfurization process of gasoline. This process uses FCC gasoline full-fraction feedstock, and the catalyst of this invention is used in the selective hydrotreating unit for hydrotreating pretreatment, causing dienes to be hydrogenated to saturation and double bonds to isomerize; small-molecule thiols and sulfides are converted into large-molecule 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 hydrodesulfurization using the selective hydrodesulfurization catalyst, minimizing olefin saturation and thus minimizing octane number loss. Detailed Implementation

[0025] In this invention, the specific surface area and pore volume were determined using a cryogenic liquid nitrogen adsorption method, while the total acid content, Brønsted acid content, and Lewis acid content were determined using pyridine infrared adsorption spectroscopy. In this invention, % represents mass percentage. The catalyst composition was determined using a colorimetric method.

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

[0027] Alumina dry adhesive powder, adhesive solvent, and extrusion aid are mixed and then extruded into strips on an extrusion molding machine. The mixture is then dried at 100–120°C for 1–5 hours, followed by calcination at a rate of 150–250°C / hour to 400–750°C for 1–5 hours to obtain a catalyst support. This support is then placed in a rotating drum, and a Mo / Ni solution with saturated water absorption capacity is sprayed onto the alumina support in a mist manner. After the solution is sprayed, the drum continues to rotate for 10–60 minutes, then left to stand for 1–24 hours. The mixture is then dried at 100–120°C for 1–5 hours, followed by calcination at a rate of 150–250°C / hour to 350–550°C for 1–5 hours to obtain the finished catalyst.

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

[0029] The catalysts used in this invention are described in detail below using examples.

[0030] Example 1

[0031] First, add 4.2g of calcium oxide to 1L of water. Then, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80℃ for 1.0h, controlling the pH value of the neutralization reaction to be 8.8-9.0. Next, add 4.9g of phosphoric acid and age for 0.5h. After washing and filtering twice, the filter cake obtained is dried at 110℃ for 24 hours and ground to obtain alumina dry adhesive powder. The dry adhesive powder is extruded into strips, then dried at 110℃ for 3 hours, and calcined at 600℃ for 3 hours to obtain the alumina carrier.

[0032] 200g of alumina support was placed in a spray-dip cauldron. Under rotating conditions, 156mL of a solution containing 10.5g of molybdenum trioxide and 67.9g of nickel nitrate was sprayed into the alumina support in the cauldron in an atomized manner. After the solution was sprayed, the cauldron was rotated for another 30 minutes, then left to stand for 18 hours, dried at 110℃ for 3 hours, and then calcined at 500℃ for 3 hours at a heating rate of 200℃ / hour to obtain the finished catalyst A.

[0033] Example 2

[0034] First, add 7g of calcium oxide to 1L of water. Then, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80℃ for 1.0h, controlling the pH value of the neutralization reaction to be 8.8-9.0. Then, add 8.17g of phosphoric acid and age for 0.5h. After washing and filtering twice, the filter cake obtained is dried at 110℃ for 24 hours and ground to obtain alumina dry adhesive powder. The dry adhesive powder is extruded into strips, then dried at 110℃ for 3 hours, and calcined at 600℃ for 3 hours to obtain the alumina carrier.

[0035] 200g of alumina support was placed in a spray-dip jar. Under rotating conditions, 170mL of a solution containing 10.8g of molybdenum trioxide and 70.3g of nickel nitrate was sprayed into the alumina support in the jar in an atomized manner. After the solution was sprayed, the jar was rotated for another 30 minutes, then left to stand for 18 hours, dried at 110℃ for 3 hours, and then calcined at 500℃ for 3 hours at a heating rate of 200℃ / hour to obtain the finished catalyst B.

[0036] Example 3

[0037] First, add 4.2g of calcium oxide to 1L of water. Then, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80℃ for 1.0h, controlling the pH value of the neutralization reaction to be 8.8-9.0. Next, add 4.9g of phosphoric acid and age for 0.5h. After washing and filtering twice, the filter cake obtained is dried at 110℃ for 24 hours and ground to obtain alumina dry adhesive powder. The dry adhesive powder is extruded into strips, then dried at 110℃ for 3 hours, and calcined at 600℃ for 3 hours to obtain the alumina carrier.

[0038] 200g of alumina support was placed in a spray-dip cauldron. Under rotating conditions, 156mL of a solution containing 24.2g of molybdenum trioxide and 84.6g of nickel nitrate was sprayed into the alumina support in the cauldron in an atomized manner. After the solution was sprayed, the cauldron was rotated for another 30 minutes, then left to stand for 18 hours, dried at 110℃ for 3 hours, and then calcined at 500℃ for 3 hours at a heating rate of 200℃ / hour to obtain the finished catalyst C.

[0039] Example 4

[0040] First, add 7g of calcium oxide to 1L of water. Then, neutralize 600mL of aluminum sulfate aqueous solution and 200mL of sodium aluminate aqueous solution at 80℃ for 1.0h, controlling the pH value of the neutralization reaction to be 8.8-9.0. Then, add 8.17g of phosphoric acid and age for 0.5h. After washing and filtering twice, the filter cake obtained is dried at 110℃ for 24 hours and ground to obtain alumina dry adhesive powder. The dry adhesive powder is extruded into strips, then dried at 110℃ for 3 hours, and calcined at 600℃ for 3 hours to obtain the alumina carrier.

[0041] 200g of alumina support was placed in a spray-dip cauldron. Under rotating conditions, 155mL of a solution containing 21.9g of molybdenum trioxide and 80.0g of nickel nitrate was sprayed into the alumina support in the cauldron in an atomized manner. After the solution was sprayed, the cauldron was rotated for another 30 minutes, then left to stand for 18 hours, dried at 110℃ for 3 hours, and then calcined at 500℃ for 3 hours at a heating rate of 200℃ / hour to obtain the finished catalyst D.

[0042] Comparative Example 1

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

[0044] Comparative Example 2

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

[0046] Comparative Example 3

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

[0048] Comparative Example 4

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

[0050] Comparative Example 5

[0051] Catalyst I was prepared using the same method as in Example 1, except that 200g of alumina support was placed in a spray-impregnation cauldron. Under rotating conditions, 156mL of a solution containing 32.8g of molybdenum trioxide and 94.4g of nickel nitrate was sprayed onto the alumina support in the cauldron in an atomized manner. After the solution was sprayed, the cauldron was rotated for another 30 minutes, then left to stand for 18 hours, dried at 110℃ for 3 hours, and then calcined at 500℃ for 3 hours with a heating rate of 200℃ / hour.

[0052] Example 6

[0053] This example compares the physicochemical properties of the catalysts prepared in the above examples with the results of operating the above examples on a small-scale hydrogenation unit for 600 hours, as shown in Tables 1 and 2.

[0054] Table 1. Main properties of the catalyst

[0055]

[0056]

[0057] Table 2. Catalyst Selective Hydrogenation Activity

[0058]

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

[0060] Table 2 lists the results of selective hydrogenation reaction experiments. It shows that the catalyst of this invention significantly reduces the diene content in the full-range gasoline, while olefins are slightly saturated. A comparison of the sulfur structures of the feedstock and reaction products (thiols and sulfides) indicates that all thiols and sulfides in the light fraction are converted, while the contents of C6 thiols, C6 sulfides, C7, and C8 sulfides in the heavy fraction are increased, demonstrating the conversion of thiols and sulfides in the light fraction to the heavy fraction. The catalyst of this invention exhibits excellent selective hydrogenation reaction performance for the removal of dienes and thiols.

Claims

1. A selective hydrogenation catalyst, characterized in that: The catalyst comprises a hydrogenation active component and a hydrogenation catalyst support. The hydrogenation active component consists of molybdenum and nickel, with a molybdenum content of 3.0–11.0% and a nickel content of 9.0–18.0% based on the weight of the catalyst oxides, and a Ni / Mo atomic molar ratio of 3.1–11.

5. The hydrogenation catalyst support comprises 71%–88% alumina and calcium phosphate, with a calcium phosphate content of 2.5%–18.0% and an alumina content of 82.0%–97.5% based on the weight of the support. The total acidity of the support is 0.45–0.75 mmol / g, the L acid content is 0.40–0.70 mmol / g, and the Brønsted acid / L acid ratio is 0.07–0.

25.

2. The catalyst according to claim 1, characterized in that: Based on the carrier weight, the calcium phosphate content is 5.0%~16.0%, the alumina content is 84.0%~95.0%, the total acid content of the carrier infrared acid is 0.50~0.70mmol / g, the L acid content is 0.35~0.65, and the B acid / L acid ratio is 0.08~0.

20.

3. The catalyst according to claim 1, characterized in that: The catalyst has a pore volume of 0.45~1.30 mL / g and a specific surface area of ​​180~400 m². 2 / g.

4. The catalyst according to claim 1, characterized in that: The catalyst includes one or more promoters selected from Ti, Zr, V, Cu, Zn, and Si. The promoter content is 0.5% to 7% based on the total weight of the catalyst, and the sum of the contents of all components of the catalyst is 100%.

5. A method for preparing a selective hydrogenation catalyst according to any one of claims 1 to 4, characterized in that... The following are included: (1) Calcium oxide is added to the bottom water of the reactor, and then aluminum salt solution and precipitant are added in parallel to neutralize and gel. After gelation, phosphoric acid is added to carry out aging reaction. The aging product is washed, filtered and dried to obtain modified alumina dry glue powder; (2) The modified alumina dry glue powder, glue solvent and extrusion aid are mixed evenly, extruded into strips, and dried and calcined to obtain hydrogenation catalyst support; (3) The active components are loaded onto the hydrogenation catalyst support according to the atomic molar ratio of Mo and Ni to obtain 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℃.

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

8. The method according to claim 5, characterized in that: The gelation reaction conditions for 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 process described in step (1) involves washing with deionized water 2-5 times until SO4 levels are reached. 2- ≤2.5%, Na + ≤0.05%, Fe 3+ ≤0.25%.

11. The method according to claim 5, characterized in that: The drying conditions for step (1) are: drying temperature 90~130℃, drying time 5~34 hours.

12. The method according to claim 5, characterized in that: The extrusion aid mentioned in step (2) is one or more of guar gum powder, cellulose, starch, and polymeric surfactant, and its dosage is 0.1% to 20.0% of the dry weight of the modified alumina dry adhesive powder in step (1); the adhesive solvent is one or more of aluminum sulfate, citric acid, nitric acid, acetic acid, and oxalic acid, and its dosage is 0.1% to 20.0% of the dry weight of the modified alumina dry adhesive powder in step (1).

13. The method according to claim 5, characterized in that: The drying and calcination conditions for step (2) are as follows: dry at 100~120℃ for 1~5 hours and calcinate at 400~750℃ for 1~5 hours.

14. The method according to claim 5, characterized in that: The loading method in step (3) is impregnation. After impregnation, the product is dried and calcined. The drying and calcination conditions are as follows: dry at 100~120℃ for 1~5 hours and calcin at 350~550℃ for 1~5 hours.

15. The application of the selective hydrotreating catalyst according to any one of claims 1 to 4 in the selective hydrodesulfurization process of gasoline.

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