Composite oxide, hydrorefining catalyst, and hydrorefining method for cracked gasoline

Abstract

The application discloses a composite oxide, a hydrofining catalyst and application thereof. The composite oxide comprises alumina and titanium dioxide, the specific surface area of the composite oxide is represented as X m 2 / g, the average pore size of the composite oxide is represented as Y nm, wherein the ratio of X to Y is 32 to 50; and the pore volume of the composite oxide is represented as Z mL / g, the ratio of X to Z is 750 to 950. The hydrofining catalyst provided by the application comprises the composite oxide and an active component, and the active component is selected from one or more of molybdenum, nickel and cobalt. The catalyst has specific structure, TiO2 is uniformly dispersed on the surface of the carrier, the catalyst has good low-temperature activity, and the catalyst has high hydrogenation activity under high space velocity.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite oxide, a hydrofining catalyst using the composite oxide as a carrier, and application of the hydrofining catalyst to hydrogenation of a C6-C10 fraction of pyrolysis gasoline. BACKGROUND

[0002] Pyrolysis gasoline contains impurities such as dienes, mono-olefins, and sulfur, and thus needs to be subjected to hydrogenation to remove all of the olefins and sulfur before being used as a raw material for extraction of benzene, toluene, and xylene or as a blending component for gasoline and diesel fuel. In the process of hydrogenating pyrolysis gasoline, a two-stage hydrogenation is generally used, in which an Al2O3 carrier loaded with a noble metal such as Pd or a non-noble metal such as Ni is used as a selective hydrogenation catalyst in the first stage to remove dienes from the raw material, and an Al2O3 carrier loaded with a metal such as Co, Mo, or Ni is used as a hydrodesulfurization catalyst in the second stage to remove mono-olefins and sulfides. Foreign countries have rapidly developed the manufacturing technology of catalysts for hydrogenation of pyrolysis gasoline. France's IFP uses two types of catalysts, LD-145 and HR-304B, in the second stage of hydrogenation. LD-145 is a Mo-Ni type catalyst, and HR-304B is a Mo-Co type catalyst. Japan's Girdler Catalyst Company has developed a Co-Mo / Al2O3 catalyst, G-35B, and UOP has developed a Co-Mo / Al2O3 catalyst, S-12. China's Beijing Chemical Research Institute's Yanshan Branch has developed BY-5, 6, and 7, which are TiO2-Al2O3 carriers loaded with Co-Mo or Co-Mo-Ni.

[0003] There is still a need in the art to develop a hydrofining catalyst suitable for hydrogenation of a C6-C10 fraction of pyrolysis gasoline, which is inexpensive and easy to obtain, suitable for industrial production, and has good low-temperature activity and high hydrogenation activity at high space velocity. SUMMARY

[0004] The present application is directed to providing a hydrofining catalyst suitable for hydrogenation of a C6-C10 fraction of pyrolysis gasoline, which is inexpensive and easy to obtain, suitable for industrial production, and has a specific structure, uniform dispersion of TiO2 on the surface of the carrier, good low-temperature activity, and high hydrogenation activity at high space velocity.

[0005] An object of the present application is to provide a composite oxide used as a carrier for a hydrofining catalyst.

[0006] Another object of the present application is to provide a hydrofining catalyst for pyrolysis gasoline (e.g., a C6-C8 fraction and a C9-C10 fraction). Still another object of the present application is to provide a method for hydrofining pyrolysis gasoline.

[0007] The composite oxide provided by the present application includes alumina and titanium dioxide, and the specific surface area of the composite oxide is expressed as X m2 / g.2 / g, the average pore size of the composite oxide is expressed as Y nm, where the ratio of X to Y is 32 to 50.

[0008] In this invention, the specific surface area of ​​the composite oxide can be determined by the BET method.

[0009] According to an embodiment of the present invention, the ratio of X to Y is 32, 33, 35, 38, 40, 42, 45, 47, 50 or any combination thereof.

[0010] According to embodiments of the present invention, the pore volume of the composite oxide is expressed as Z mL / g, and the ratio of X to Z is 750 to 950. In some embodiments, the ratio of X to Z is 780, 800, 820, 840, 850, 860, 870, 880, 890, 900, 910, or any combination thereof.

[0011] According to embodiments of the present invention, X is 300 to 350. In some embodiments, X is 300, 310, 320, 330, 340, 350, or a range of any two thereof.

[0012] According to embodiments of the present invention, Y is 8 to 9, preferably 8 to 8.5. In some embodiments, Y is 8.1, 8.2, 8.3, 8.4, 8.5, or a range of any two thereof.

[0013] According to embodiments of the present invention, Z is from 0.30 to 0.45, preferably from 0.35 to 0.40. In some embodiments, Z is within the range of 0.35, 0.36, 0.37, 0.38, 0.39, or any combination thereof.

[0014] According to an embodiment of the present invention, the composite oxide contains 5 wt% to 21 wt% titanium dioxide.

[0015] According to an embodiment of the present invention, the method for preparing the composite oxide includes the following steps:

[0016] Step I. Dissolve soluble aluminum salts in water to form an aluminum salt solution, dissolve titanium salts in an acid solution to form a titanium salt solution, and mix ammonium salts and alkaline solutions to form a mixed alkaline solution;

[0017] Step II. (a) Add the titanium salt solution and the mixed alkaline solution to the aluminum salt solution, so that the mixture is maintained at the first pH value for a first time period; (b) Stop adding the titanium salt solution and continue adding the mixed alkaline solution, so that the mixture is maintained at the second pH value for a second time period; (c) Stop adding the mixed alkaline solution and add the titanium salt solution, so that the mixture is maintained at the third pH value for a third time period.

[0018] Step III. After step II.(c), the temperature of the mixture is raised and maintained for a fourth time period to obtain a precipitate;

[0019] Step IV. The precipitate is dried and calcined to obtain a composite oxide containing aluminum oxide and titanium dioxide. Preferably, the precipitate is also washed and filtered before drying.

[0020] According to some embodiments of the present invention, in step II, the first pH value is less than 5, preferably 3 to 4. According to some embodiments of the preparation method of the present invention, in step II, the second pH value is greater than 8.5, preferably 9 to 10. According to some embodiments of the preparation method of the present invention, in step II, the third pH value is greater than 7 and less than 9, preferably 7.5 to 8.5.

[0021] According to some embodiments of the present invention, in step II, the first time period, the second time period, and the third time period are 5 to 20 minutes, preferably 10 to 15 minutes.

[0022] According to some embodiments of the present invention, in step II, the fourth time period is 20 minutes to 60 minutes.

[0023] According to some embodiments of the present invention, in step III, the operating temperature is 25°C to 60°C, preferably 50°C to 60°C.

[0024] According to some embodiments of the present invention, in step III, the temperature is raised to 80°C to 150°C, preferably 80°C to 100°C. In some embodiments, in step III, the temperature is raised to 82°C, 85°C, 90°C, 92°C, or 95°C.

[0025] According to some embodiments of the present invention, in step IV, the drying temperature is 110°C to 130°C.

[0026] According to some embodiments of the present invention, in step IV, the calcination temperature is 400°C to 600°C. In some embodiments, in step IV, the calcination temperature is 400°C, 450°C, 500°C, 550°C, or 600°C.

[0027] According to some embodiments of the present invention, the concentration of the aluminum salt is 0.5 to 2.5 mol / L. The aluminum salt is a soluble aluminum salt, and may be selected from one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and other organic salts of aluminum.

[0028] According to some embodiments of the present invention, the concentration of the titanium salt is 0.2 to 1.2 mol / L. According to some embodiments of the preparation method of the present invention, the concentration of the ammonium salt is 0.1 to 0.3 mol / L. The ammonium salt may be selected from one or more of ammonium bicarbonate, ammonium carbonate, and other organic ammonium salts.

[0029] According to some embodiments of the present invention, the concentration of the alkaline solution is 0.2 to 0.4 mol / L. The alkaline solution may be one or more of ammonia, sodium hydroxide, potassium hydroxide, and other organic bases.

[0030] According to some embodiments of the present invention, the acid solution may be selected from one or more of sulfuric acid, nitric acid, hydrochloric acid and other organic acids.

[0031] This invention provides the application of the above-mentioned composite oxide as a catalyst support. Preferably, the catalyst is a hydrogenation catalyst.

[0032] This invention provides a hydrorefining catalyst comprising the composite oxide described herein and an active component, wherein the active component is selected from one or more of molybdenum, nickel, and cobalt; preferably, the content of molybdenum and / or molybdenum oxide is 8 wt% to 20 wt%; the content of nickel and / or nickel oxide is 1 wt% to 10 wt%; and the content of cobalt and / or cobalt oxide is 0 wt% to 8 wt%.

[0033] The present invention provides a method for hydrorefining cracked gasoline, which includes hydrorefining cracked gasoline in the presence of the hydrorefining catalyst described in the present invention.

[0034] This invention is applied to the hydrogenation of C6-C8 and C9-C10 fractions of cracked gasoline. When applied to the hydrogenation of C6-C8 fractions, the reactor inlet temperature is 220-280°C and the space velocity is 2-4 h⁻¹. -1 The hydrogen-to-oil ratio is 300:1 to 500:1, and the pressure is 2.5 to 3.5 MPa. When applied to C9 to C10 hydrogenation, the reactor inlet temperature is 220 to 300°C, and the space velocity is 1 to 2 h⁻¹. -1 The hydrogen-to-oil ratio is 400:1 to 800:1, and the pressure is 2.5 to 3.5 MPa. Before the reaction begins, the reactor temperature should be 280 to 350°C, the hydrogen-to-oil ratio should be 100 to 200:1, a cyclohexane solution with a DMDS content of 1% to 5% should be used, and the space velocity should be 1 to 2 h⁻¹. -1 Vulcanize for 10–24 hours, then lower the temperature to room temperature.

[0035] Compared with existing catalysts, the hydrorefining catalyst provided by the present invention has higher low-temperature activity and higher hydrogenation activity at high space velocities in the field of hydrogenation of C6-C8 and C9-C10 fractions of cracked gasoline. Detailed Implementation

[0036] To facilitate understanding of the present invention, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0037] Unless otherwise specified, all raw materials or components used in this invention can be obtained through commercial means or conventional methods.

[0038] The specific surface area and pore structure of the composite oxides were determined using an ASAP 2020 adsorption analyzer (N2 adsorption method) from Micron Instruments, USA. Before testing, the composite oxide samples were degassed at 623 K for 4 h, and nitrogen was adsorbed at liquid nitrogen temperature. Sample data were processed using AMSM software, and the specific surface area was obtained using the Brunauer-Emmet-Teller (BET) method. The average pore size was obtained from the nitrogen adsorption isotherm using the Barrett-Joyner-Halenda (BJH) method, and the pore volume was obtained using the P / Po single-point desorption curve.

[0039] Example 1

[0040] 328.02 g of Al2(SO4)3 was dissolved in deionized water to prepare 1000 mL of aluminum sulfate solution. 21.14 g of TiO(OH)2 was dissolved in sulfuric acid solution, and deionized water was added to prepare 500 mL of dilute sulfuric acid solution containing metatitanic acid. 18 g of NH4HCO3 was dissolved in 600 mL of deionized water to prepare ammonium bicarbonate solution, then 250 mL of 24–28 wt% ammonia solution was added, stirred until homogeneous, and then deionized water was added to prepare 1000 mL of mixed alkali solution.

[0041] At atmospheric pressure and 55°C, the above-mentioned dilute sulfuric acid solution of metatitanic acid and the mixed alkali solution were added to the aluminum sulfate solution in parallel flow while maintaining vigorous stirring. The pH of the mixed solution was maintained in the range of 3 to 4 for 15 minutes. The addition of titanium salt solution was stopped, and the mixed alkali was continued to be added to make the pH 9 to 10. This was maintained in this range for 15 minutes. The addition of mixed alkali was stopped, and the above-mentioned dilute sulfuric acid solution of metatitanic acid was added to adjust the pH to 7.5 to 8.5. This was maintained for 6 to 10 minutes. The temperature was raised to 92°C and maintained for 20 minutes. The mixture was filtered, and the filter cake was washed repeatedly 5 times with 20 times the volume of deionized water. The washed filter cake was dried at 110°C for 6 hours and calcined at 550°C for 5 hours to obtain 114.3 g of TiO2-Al2O3 composite oxide support 1 with a TiO2 content of 15.1 wt%.

[0042] Example 2

[0043] 401.28g of Al2(SO4)3 was dissolved in deionized water to prepare 1000mL of aluminum sulfate solution. 20.40g of TiO(OH)2 was dissolved in sulfuric acid solution, and deionized water was added to prepare 500mL of dilute sulfuric acid solution containing metatitanic acid. 18g of NH4HCO3 was dissolved in 600mL of deionized water to prepare ammonium bicarbonate solution, and then 250mL of 24-28wt% ammonia solution was added. The mixture was stirred until homogeneous, and then deionized water was added to prepare 1000mL of mixed alkali solution. Under normal pressure and at 60℃, the above dilute sulfuric acid solution containing metatitanic acid and the mixed alkali solution were added concurrently to the aluminum sulfate solution, maintaining vigorous stirring. The pH of the mixed solution was maintained within the range of 3 to 4 for 15 minutes. The addition of titanium salt solution was stopped, and the mixed alkali solution was continued to be added until the pH reached 9 to 10. This was maintained within this range for 15 minutes. The addition of mixed alkali was then stopped, and acid solution was added to adjust the pH to 7.5 to 8.5. The temperature was raised to 85℃ and maintained for 40 min. The mixture was then filtered, and the filter cake was washed repeatedly five times with 20 times its volume of deionized water. The washed filter cake was dried at 110℃ for 6 h and then calcined at 600℃ for 5 h. 136.2 g of TiO2-Al2O3 composite oxide support 2 with a TiO2 content of 12.2 wt% was obtained.

[0044] Example 3

[0045] The conditions in Example 3 were the same as in Example 1, except that the relative concentrations of the aluminum sulfate deionized aqueous solution and the dilute sulfuric acid solution of metatitanic acid were adjusted to ensure that the TiO2 content of the prepared TiO2-Al2O3 composite carrier 3 was 9.3 wt%.

[0046] Example 4

[0047] The conditions for Example 4 were the same as those for Example 1, except that the relative concentrations of the aluminum sulfate deionized aqueous solution and the dilute sulfuric acid solution of metatitanic acid were adjusted to ensure that the TiO2 content of the prepared TiO2-Al2O3 composite oxide carrier 4 was 20.0 wt%.

[0048] Example 5

[0049] The conditions in Example 5 were the same as in Example 1, except that the relative concentrations of the aluminum sulfate deionized aqueous solution and the dilute sulfuric acid solution of metatitanic acid were adjusted to ensure that the prepared composite carrier 5 had a TiO2 content of 5.0 wt% TiO2-Al2O3 composite oxide carrier 5.

[0050] Comparative Example 1:

[0051] Alumina powder and metatitanic acid (TiOSO4) with a mass ratio of 5:1 were mixed and placed in a screw extruder; water and acid were added and extruded, dried at 110°C, and calcined in a muffle furnace at 550°C to obtain TiO2-Al2O3 composite carrier.

[0052] Comparative Example 2

[0053] Take 401.88g of analytically pure AlCl3·6H2O and dissolve it in 1000ml of deionized water to prepare solution A1; take 43.25g of chemically pure Ti(OCH2CH3)4 and dissolve it in 500ml of benzene (benzene content is 99.8(wt)%) to prepare solution B1; take 18g of analytically pure NH4HCO3 and dissolve it in 600ml of deionized water, add 250ml of ammonia water with a concentration of 24-28wt%, stir and mix evenly, and then add deionized water to prepare 1000ml of solution C1.

[0054] Under normal pressure and at a temperature of 70-75℃, solutions A1, B1, and C1 were co-precipitated by parallel flow. The flow rate of solution C1 was controlled to maintain the pH of the precipitate in the range of 5.0-6.0 for 8 minutes. Then, the flow rate of solution C1 was increased to maintain the pH of the mixed solution in the range of 8.5-9.5 for 8 minutes. Then, the flow rate of solution C1 was decreased to maintain the pH of the mixed solution in the range of 5.0-6.0 for 8 minutes. Then, the flow rate of solution C1 was increased again to maintain the pH of the precipitate in the range of 8.5-9.5. This process was repeated until all solutions A1 and B1 were added. The reaction solution was allowed to stand at 70℃ for 30 minutes, filtered, and the filter cake was washed with 15 times the volume of deionized water for 30 minutes. This process was repeated four times. Finally, the filter cake was dried at 100-120℃ for 8-12 hours and calcined at 550℃ for 5 hours to obtain 42.7g of titanium dioxide-alumina composite. The results of its structure and performance are shown in Table 1.

[0055] Table 1. Analytical data of titanium dioxide-alumina composites

[0056]

[0057] Catalyst preparation

[0058] Example 6

[0059] Ammonium molybdate, nickel nitrate, and cobalt nitrate were dissolved in water and impregnated with the TiO2-Al2O3 composite support 4 prepared in Example 4. The mixture was dried at 110°C for 2 hours and calcined at 550°C for 4 hours to obtain MoO3-CoO-NiO / Al2O3-TiO2 hydrogenation refining catalyst A with a MoO3 content of 15%, a CoO content of 2%, and a NiO content of 4%.

[0060] Example 7

[0061] Ammonium molybdate, nickel nitrate, and cobalt nitrate were dissolved in water and impregnated with the TiO2-Al2O3 composite support 1 prepared in Example 1. The mixture was dried at 110°C for 4 hours and calcined at 550°C for 6 hours to obtain MoO3-CoO-NiO / Al2O3-TiO2 hydrogenation refining catalyst B with a MoO3 content of 15%, a CoO content of 3.5%, and a NiO content of 3%.

[0062] Example 8

[0063] Ammonium molybdate and nickel nitrate were dissolved in water and impregnated with the TiO2-Al2O3 composite support 5 prepared in Example 5. The mixture was dried at 110°C for 2 hours and calcined at 550°C for 4 hours to obtain MoO3-CoO-NiO / Al2O3-TiO2 hydrogenation refining catalyst C with a MoO3 content of 8.5% and a NiO content of 10.5%.

[0064] Comparative Example 3

[0065] Ammonium molybdate, nickel nitrate, and cobalt nitrate were dissolved in water and impregnated with the TiO2-Al2O3 composite support in Comparative Example 1. The mixture was then dried and calcined at 550℃ for 4 hours to obtain MoO3-CoO-NiO / Al2O3-TiO2 hydrogenation refining catalyst C-1 with a MoO3 content of 15%, a CoO content of 2%, and a NiO content of 4%.

[0066] Comparative Example 4

[0067] Ammonium molybdate, nickel nitrate, and cobalt nitrate were dissolved in water and impregnated with the TiO2-Al2O3 composite support in Comparative Example 2. The mixture was dried and calcined at 550℃ for 4 hours to obtain MoO3-CoO-NiO / Al2O3-TiO2 hydrogenation refining catalyst C-2 with a MoO3 content of 15%, a CoO content of 2%, and a NiO content of 4%.

[0068] Example 9

[0069] The hydrogenation product of the C6-C8 fraction stage of a petrochemical benzene production unit was used as the feedstock for hydrorefining. The total sulfur content of the feedstock was 98 ppm, and the bromine value was 19.09 (gBr2 / 100g oil). Catalysts A, B, C-1, and C-2 were compared and evaluated. Evaluation conditions and product analysis are shown in Table 2.

[0070] Table 2. Analysis results of hydrogenation products.

[0071]

[0072]

[0073] As shown in Table 2, the catalyst prepared according to this invention performs well in the hydrorefining reaction of C6-C8 fraction feedstocks, especially at high space velocities (4 h⁻¹). -1 Under these conditions, it exhibits excellent hydrogenation saturation performance and hydrodesulfurization performance for olefins.

[0074] Example 10

[0075] C9~C from a certain chemical plant 10 The feedstock for the two-stage hydrogenation process had a total sulfur content of 400 ppm and a bromine value of 29 (gBr2 / 100g oil). Comparative evaluations were conducted using catalysts A, C, and C-1, and the results are shown in Table 3.

[0076] Table 3

[0077]

[0078] As shown in Table 3, the catalyst prepared according to this invention performs well in the hydrorefining reaction of C9-C10 heavy fraction feedstocks, especially at high space velocities (1.5 h⁻¹). -1 Under these conditions, it exhibits excellent hydrogenation saturation performance and hydrodesulfurization performance for olefins.

[0079] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A composite oxide comprising aluminum oxide and titanium dioxide, wherein the specific surface area of ​​the composite oxide is expressed as X m 2 / g, the average pore size of the composite oxide is expressed as Y nm, where, The ratio of X to Y is 32 to 42; and the pore volume of the composite oxide is expressed as Z mL / g, with the ratio of X to Z being 780 to 950. X is 310 to 350; Y is 8 to 8.5; Z is 0.30 to 0.39; The preparation method of the composite oxide includes the following steps: Step I. Dissolve soluble aluminum salts in water to form an aluminum salt solution, dissolve titanium salts in an acid solution to form a titanium salt solution, and mix ammonium salts and alkaline solutions to form a mixed alkaline solution; Step II. (a) Add the titanium salt solution and the mixed alkali solution to the aluminum salt solution, so that the mixture is maintained at the first pH value for a first time period; (b) Stop adding the titanium salt solution and continue adding the mixed alkali solution, so that the mixture is maintained at the second pH value for a second time period; (c) Stop adding the mixed alkali solution and add the titanium salt solution, so that the mixture is maintained at the third pH value for a third time period. Step III. After step II.(c), the temperature of the mixture is raised and maintained for a fourth time period to obtain a precipitate; Step IV. The precipitate is dried and calcined to obtain a composite oxide containing alumina and titanium dioxide; In step II, the first pH value is less than 5, the second pH value is greater than 8.5, and the third pH value is greater than 7 and less than 9; The first, second, and third time periods are each 5 to 20 minutes long.

2. The composite oxide according to claim 1, characterized in that, In step IV, washing and filtration are also performed before drying.

3. The composite oxide according to claim 1, characterized in that, In step II, the first pH value is 3 to 4, the second pH value is 9 to 10, and the third pH value is 7.5 to 8.

5.

4. The composite oxide according to claim 1, characterized in that, The first, second, and third time periods are each 10 to 15 minutes; and / or The fourth time period is from 20 to 60 minutes.

5. The composite oxide according to claim 1, characterized in that, In step II, the operating temperature is 25°C to 60°C; and / or in step III, the temperature is increased to 80°C to 150°C; and / or in step IV, the drying temperature is 110°C to 130°C; and / or the calcination temperature is 400°C to 600°C.

6. The application of the composite oxide as a catalyst support according to any one of claims 1-5.

7. A hydrorefining catalyst comprising a composite oxide according to any one of claims 1-5 and an active component, wherein the active component is selected from one or more of molybdenum, nickel, and cobalt.

8. The hydrorefining catalyst according to claim 7, characterized in that, The content of molybdenum and / or molybdenum oxide is 8 wt% to 20 wt%; the content of nickel and / or nickel oxide is 1 wt% to 10 wt%; and the content of cobalt and / or cobalt oxide is 0 wt% to 8%.

9. A method for hydrorefining cracked gasoline, comprising hydrotreating cracked gasoline in the presence of the catalyst described in claim 7 or 8.

10. The method for hydrorefining cracked gasoline according to claim 9, characterized in that, When the cracked gasoline is a C6-C8 fraction, the reactor inlet temperature is 220-280°C and the space velocity is 2-4 h⁻¹. -1 The hydrogen-to-oil ratio is 300:1 to 500:1, and the pressure is 2.5 to 3.5 MPa.

11. The method for hydrorefining cracked gasoline according to claim 9, characterized in that, When the cracked gasoline is C9~C 10 During distillation, the reactor inlet temperature is 220~300℃, and the space velocity is 1~2h. -1 The hydrogen-to-oil ratio is 400:1 to 800:1, and the pressure is 2.5 to 3.5 MPa.

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