A diesel hydro-upgrading catalyst, its preparation method and application
By preparing catalysts based on HZSM-23 molecular sieves and modified Y molecular sieves, the problem of excessive cracking of long-chain alkanes caused by existing diesel hydroretrograding catalysts was solved, achieving high yield and good flow properties of diesel products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing diesel hydrotreating catalysts tend to cause excessive cracking of long-chain alkanes when processing low-quality diesel fuel rich in aromatics and cycloalkanes, which affects the yield and low-temperature flow properties of diesel products.
The catalyst is prepared by using HZSM-23 molecular sieve and modified Y molecular sieve as the main components, combined with macroporous alumina and hydrogenation active components, through molding, drying, calcination and impregnation. This ensures that the outer surface and pores of the catalyst are mainly composed of weak Brønsted acid, thereby improving the cetane number and low-temperature flow properties of diesel products.
It significantly improved the cetane number and low-temperature flow properties of diesel products, while also increasing the yield of diesel products.
Smart Images
Figure SMS_1 
Figure SMS_2
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, and relates to a diesel hydrotreating catalyst, its preparation method and application. Background Technology
[0002] Catalytic cracking units are among the most important units in oil refineries. These catalytic diesel fuels have high aromatic and sulfur content, low cetane number, high density, and poor oxidation stability. They often need to be hydrotreated before they can be converted into automotive diesel or other high-quality feedstocks.
[0003] Diesel hydrotreating technology typically involves the appropriate cracking of aromatics and cycloalkanes in diesel fuel under medium-pressure conditions, altering the composition of hydrocarbons and thereby improving diesel product quality. An ideal diesel hydrotreating catalyst should possess good ring-opening properties for aromatics and cycloalkanes while retaining the alkanes in the feedstock, thus improving the combustion performance of diesel fuel and maximizing its low-temperature fluidity. Currently, widely used industrial diesel hydrotreating catalysts primarily utilize modified Y-zeolite and / or β-zeolite as cracking components.
[0004] Patent CN201410453058.1 discloses a YB molecular sieve, its preparation method, and its application. The method includes: (1) mixing a Y-type molecular sieve and a β-type molecular sieve and immersing them in an aqueous solvent; separating the solid from the immersed material, drying it, and then calcining it to obtain a first solid; (2) contacting the first solid with an acidic solution; separating the solid from the contacted material and drying it to obtain a second solid; and (3) subjecting the second solid to hydrothermal treatment. In this patent, the high proportion of strong Brønsted acid on the catalyst's outer surface and pores easily leads to excessive cracking of long-chain alkanes to generate short-chain alkanes or dry gas, affecting the yield of diesel products and their low-temperature flow properties. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a diesel hydrotreating catalyst, its preparation method, and its applications. The catalyst's outer surface and pore pores are predominantly composed of weak Brønsted acid sites. When processing low-quality diesel, especially diesel rich in aromatics and cycloalkanes, it can significantly improve the cetane number and low-temperature flow properties of the diesel product, while also increasing the product yield.
[0006] This invention provides a diesel hydrotreating catalyst, which, based on the weight of the catalyst, comprises the following components:
[0007] a) HZSM-23 molecular sieve, with a content of 2-13 wt%, preferably 4-12 wt%;
[0008] b) Modified Y molecular sieve, with a content of 3-20 wt%, preferably 5-18 wt%;
[0009] c) Macroporous alumina, with a content of 30-65 wt%, preferably 35-60 wt%;
[0010] d) The hydrogenation active component is selected from Group VIB metals and / or Group VIII metals, wherein the content of Group VIB metals as oxides is 10 to 30 wt%, preferably 12 to 25 wt%, and the content of Group VIII metals as oxides is 2 to 10 wt%, preferably 3 to 8 wt%.
[0011] In the 2,6-dimethylpyridine infrared Brønsted acid of the catalyst, the proportion of weak Brønsted acid is 48% to 74%, preferably 50% to 72%.
[0012] In the above catalyst, the total Brønsted acid content of 2,6-dimethylpyridine in infrared radiation is 0.071 to 0.239 mmol / g, preferably 0.080 to 0.227 mmol / g.
[0013] In the above catalyst, the total Brønsted acid content of pyridine in infrared is 0.125-0.310 mmol / g, preferably 0.134-0.295 mmol / g; preferably, the ratio of the total Brønsted acid content of 2,6-dimethylpyridine in infrared to the total Brønsted acid content of pyridine in infrared is 35-77:100, more preferably 37-75:100.
[0014] The modified Y molecular sieve in the above catalyst has the following properties: SiO2 / Al2O3 molar ratio of 20–40, cell parameter of 2.464–2.469, and specific surface area of 730–840 m². 2 / g, pore volume 0.40~0.56cm³ 3 / g.
[0015] In the above catalyst, the macroporous alumina has the following properties: specific surface area of 375–450 m². 2 / g, pore volume 0.74~1.15cm 3 / g; preferably, specific surface area is 390-430m² 2 / g, pore volume 0.78~1.10cm 3 / g.
[0016] In the above catalyst, the group VIB metal is tungsten and / or molybdenum, and the group VIII metal is nickel and / or cobalt.
[0017] This invention also provides a method for preparing a diesel hydrotreating catalyst, the method comprising the following steps:
[0018] (1) HZSM-23 molecular sieve, modified Y molecular sieve, macroporous alumina and binder are mixed, shaped, dried and calcined to obtain a carrier; in the 2,6-dimethylpyridine infrared Brønsted acid of the HZSM-23 molecular sieve, the proportion of weak Brønsted acid is 64% to 95%, preferably 67% to 93%.
[0019] (2) The carrier obtained in step (2) is impregnated with a solution containing hydrogenation active components, and then dried and calcined to obtain a diesel hydrotreating catalyst.
[0020] In the above preparation method, the total 2,6-dimethylpyridine Brønsted acid content of the HZSM-23 molecular sieve in step (1) is 0.114 to 0.249 mmol / g, preferably 0.125 to 0.236 mmol / g.
[0021] In the above preparation method, the total β-acid content of pyridine in the infrared radiation of the HZSM-23 molecular sieve in step (1) is 0.143-0.398 mmol / g, preferably 0.158-0.380 mmol / g; the ratio of the total β-acid content of 2,6-dimethylpyridine to the total β-acid content of pyridine in the infrared radiation is 65-96:100, preferably 69-93:100.
[0022] In the above preparation method, the binder in step (1) can be a conventional binder in the prior art, such as one or more of nitric acid, guar gum powder, methylcellulose, and polyacrylamide, preferably nitric acid and / or guar gum powder.
[0023] In the above preparation method, the molding in step (1) can be any of the molding methods in the prior art, including but not limited to extrusion, sheeting, and pelletizing, preferably extrusion.
[0024] In the above preparation method, the drying and calcination conditions in step (1) are as follows: the drying temperature is 60-130℃ and the time is 2-12h, preferably the drying temperature is 80-120℃ and the time is 4-8h; the calcination temperature is 500-600℃ and the time is 2-8h, preferably the calcination temperature is 530-570℃ and the time is 3-6h.
[0025] In the above preparation method, the hydrogenation active component in step (2) is selected from Group VIB metals and / or Group VIII metals, wherein the Group VIB metals are preferably tungsten and / or molybdenum, and the Group VIII metals are preferably nickel and / or cobalt.
[0026] In the above preparation method, the impregnation in step (2) can be carried out by saturated impregnation or supersaturated impregnation, preferably by saturated impregnation.
[0027] In the above preparation method, the drying and calcination conditions in step (2) are as follows: drying at 80-120℃ for 4-12 hours and calcining at 400-700℃ for 3-12 hours.
[0028] The present invention also provides the application of the above-mentioned diesel hydrotreating catalyst in the diesel hydrotreating process.
[0029] In the above applications, the total mass content of aromatics and cycloalkanes in the diesel fuel is 50-90%, preferably 55-86%; wherein, the mass content of aromatics is 10-40%, preferably 15-34%; and the mass content of cycloalkanes is 30-82%, preferably 35-71%.
[0030] In the above applications, the diesel fuel has the following properties: a distillation range of 180–400°C, a sulfur content of 300–800 ppm, and a nitrogen content of 1000–1500 ppm.
[0031] In the above applications, the reaction conditions for the diesel hydrotreating process are: reaction temperature 350–400℃, total reaction pressure 5.0–10.0 MPa, and liquid hourly space velocity 0.5–3 h⁻¹. -1 The hydrogen-to-oil volume ratio is 400:1 to 1000:1.
[0032] Compared with existing technologies, the diesel hydrotreating catalyst, its preparation method, and its application provided by this invention have the following advantages:
[0033] (1) In the diesel hydrotreating catalyst provided by the present invention, the catalyst uses HZSM-23 molecular sieve and modified Y molecular sieve as cracking components, and the Brønsted acid sites on the outer surface and pores are mainly weak Brønsted acid; furthermore, the proportion of Brønsted acid content on the outer surface and pores is relatively high. When the catalyst is applied to the hydrotreating process of inferior diesel, especially inferior diesel rich in aromatics and cycloalkanes, it can significantly improve the cetane number and low-temperature flow properties of diesel products, and at the same time improve the product yield.
[0034] (2) In the preparation method of the diesel hydroretrograde catalyst provided by the present invention, HZSM-23 molecular sieve with special acidity is mixed with modified Y molecular sieve, macroporous alumina and binder, shaped, dried and calcined to obtain a support, and finally a hydroretrograde catalyst with weak B acid sites on the outer surface and pores is prepared. Detailed Implementation
[0035] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0036] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0037] In this invention, "total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy" is used to represent the amount of Brønsted acid distributed at the pore openings and outer surface of the sample, wherein the Brønsted acid sites corresponding to a desorption temperature less than 250°C are considered as weak Brønsted acid sites distributed at the pore openings and outer surface of the sample. The determination is performed using 2,6-dimethylpyridine adsorption infrared spectroscopy. The specific process involves preparing the molecular sieve sample into a self-supporting wafer (5-6 mg / cm³). 2 The sample was placed in an in-situ cell and treated under vacuum at 400℃ for 4 hours, then cooled to 50℃, and spectra were collected. After adsorbing 2,6-dimethylpyridine for 10 minutes, the sample was heated to 150℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected to calculate the total Brønsted acid content of 2,6-dimethylpyridine in the infrared spectrum. The sample was then heated to 250℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected to calculate the Brønsted acid content of 2,6-dimethylpyridine in the infrared spectrum for Brønsted acid with a desorption temperature <250℃. The Brønsted acid content was calculated according to the Lambert-Beer law, using a 1630 cm⁻¹ spectral density. -1 1650cm -1 The amount of Brønsted acid is calculated by measuring the area of the absorption peak.
[0038] In this invention, "total Brønsted acid content in pyridine infrared spectroscopy" is used to represent the total Brønsted acid content in the sample, including Brønsted acid on the outer surface of the sample, at the pore openings, and within the pores. It is determined by pyridine adsorption infrared spectroscopy. The specific process is as follows: the sample is prepared into a self-supporting wafer (5-6 mg / cm³). 2 (Molecular sieves can be prepared directly, while catalysts need to be ground into powder of approximately 200 mesh). The sample was placed in an in-situ cell and treated under vacuum at 400℃ for 4 hours, then cooled to 50℃, and spectra were collected. After adsorbing pyridine for 10 minutes, the sample was heated to 150℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected. The total Brønsted acid content of pyridine was calculated. The Brønsted acid content was calculated according to Lambert-Beer's law, using a 1540 cm⁻¹ spectral density. -1 The amount of Brønsted acid is calculated by measuring the area of the absorption peak.
[0039] In this invention, the preparation process of HZSM-23 molecular sieve is as follows:
[0040] (1) A mixture of silicon source, template agent a and water is subjected to a crystallization reaction, and a solid material is separated from the reacted material; the solid material, aliphatic amine and inorganic base are mixed and reacted once, and then ZSM-23 seed crystals are added and reacted twice.
[0041] (2) Mix the aluminum source, template agent b and the material obtained from the secondary reaction in step (1), and then crystallize, filter, wash, dry and calcine in sequence to obtain NaZSM-23 molecular sieve;
[0042] (3) The NaZSM-23 molecular sieve obtained in step (2) is subjected to ammonium exchange treatment to obtain HZSM-23 molecular sieve.
[0043] In the above preparation method, in step (1), the molar ratio of water, the template agent a and the silicon source (calculated as SiO2) is (20-80):(0.1-1):1, preferably (30-70):(0.15-0.8):1.
[0044] In the above preparation method, in step (1), the silicon source is one or any combination of at least two of the following: silica, silica sol, water glass, fumed silica and tetraethyl orthosilicate.
[0045] In the above preparation method, in step (1), the template agent a is one or any combination of at least two of hexamethylenediamine, n-hexamethyleneamine, ethanol, tetrapropylammonium hydroxide, tetrapropylammonium bromide and triethylamine.
[0046] In the above preparation method, in step (1), the conditions for the crystallization reaction include: a temperature of 120 to 220°C and a time of 8 to 48 hours.
[0047] In the above preparation method, in step (1), the liquid-to-solid ratio of the fatty amine to the solid material is 0.3-3 mL / g, preferably 0.5-2 mL / g.
[0048] In the above preparation method, in step (1), the fatty amine is a C12-C18 fatty amine, more preferably at least one of oleylamine, octadecylamine and dodecylamine.
[0049] In the above preparation method, in step (1), the inorganic base is used in the form of an alkaline solution, and the concentration of the alkaline solution is 0.003 to 0.015 mol / L, preferably 0.005 to 0.01 mol / L.
[0050] In the above preparation method, in step (1), the liquid-to-solid ratio of the alkaline solution to the solid material is 2-15 mL / g, preferably 4-10 mL / g.
[0051] In the above preparation method, in step (1), the inorganic base is at least one of sodium hydroxide, potassium hydroxide and ammonia water.
[0052] In the above preparation method, in step (1), the temperature of the secondary reaction is higher than the temperature of the primary reaction.
[0053] In the above preparation method, in step (1), the conditions for the first reaction include: a temperature of 20-40°C and a time of 3-15 h.
[0054] In the above preparation method, in step (1), the conditions for the secondary reaction include: a temperature of 60 to 120°C and a time of 6 to 30 hours.
[0055] In the above preparation method, in step (1), the amount of ZSM-23 seed crystals used is 0.1 to 8 parts by weight, preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of the solid material.
[0056] In the above preparation method, in step (2), the molar ratio of the template agent b, the aluminum source (calculated as Al2O3), and the material obtained from the secondary reaction in step (1) (calculated as SiO2) is (0.01~0.1):(0.002~0.015):1, preferably (0.02~0.08):(0.005~0.01):1.
[0057] In the above preparation method, in step (2), the template agent b is one or any combination of at least two of pyrrolidine, isopropylamine, N,N-dimethylformamide, dimethylamine and ethylenediamine.
[0058] In the above preparation method, in step (2), the aluminum source is one or any combination of at least two of aluminum sulfate, aluminum isopropoxide, sodium aluminate and aluminum hydroxide.
[0059] In the above preparation method, in step (2), the crystallization conditions include: a temperature of 180 to 220°C and a time of 24 to 72 hours.
[0060] In the above preparation method, the drying conditions in step (2) include: a temperature of 80-120°C and a time of 6-12 hours.
[0061] In the above preparation method, the calcination conditions in step (2) include: a temperature of 540-560°C and a time of 3-8 hours.
[0062] In the above preparation method, in step (3), the ammonium exchange treatment can be carried out using conventional methods in the prior art. Specifically, in this invention, the NaZSM-23 molecular sieve is placed in an ammonium nitrate solution with a concentration of 0.2 to 3.0 mol / L, wherein the liquid-to-solid ratio is 5 to 20, and stirred continuously in a water bath at 60 to 100°C for 0.5 to 4 hours. The above process can be repeated multiple times until the Na2O content in the ZSM-23 molecular sieve after ammonium exchange is less than 0.1 wt%. Then, it is washed, dried, and calcined. The drying temperature is 60 to 130°C and the time is 2 to 12 hours, preferably 80 to 120°C and the time is 4 to 8 hours. The calcination temperature is 500 to 600°C and the time is 2 to 8 hours, preferably 530 to 570°C and the time is 3 to 6 hours.
[0063] Example 1
[0064] (1) Preparation of HZSM-23 molecular sieve
[0065] 4.68 g of hexamethylenediamine was dissolved in 54 g of deionized water, and then 6 g of fumed silica was added. After stirring at room temperature (25 °C) for 1 h, the mixture was transferred to a 100 mL reactor with a polytetrafluoroethylene liner. The mixture was crystallized at 150 °C for 24 h, then quenched and centrifuged to obtain 6.43 g of solid material.
[0066] Add 10 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at room temperature for 0.5 h at a stirring rate of 200 rpm. Then add 42 mL of 0.008 mol / L NaOH solution to the mixture and carry out a first reaction at 25 °C with stirring for 6 h at a stirring rate of 200 rpm to obtain mixture A. Add 0.18 g of ZSM-23 seed crystals to deionized water to prepare 10 mL of ZSM-23 seed crystal solution, add it to mixture A, and carry out a second reaction at 80 °C with stirring for 16 h at a stirring rate of 300 rpm to obtain material B.
[0067] 0.67 g of Al2(SO4)3·18H2O and 0.40 g of pyrrolidine were added sequentially to 20 mL of deionized water to obtain a clear solution C. Solution C was added to the material B, and after thorough mixing, the final mixture was transferred to a 150 mL reactor lined with polytetrafluoroethylene and crystallized at 180 °C for 48 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain ZSM-23 molecular sieve Z-1.
[0068] Weigh the Z-1 sample and place it in a 1 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. Stir continuously in a water bath at 80–90 °C for 1 hour, then filter and wash. Repeat the above operation twice, then dry the sample in a 100 °C oven for 8 hours, and then calcine it in air at 550 °C for 3 hours to obtain HZ-1. The specific properties are shown in Table 1.
[0069] (2) Catalyst preparation
[0070] Macroporous alumina (specific surface area 408m²) accounting for 50wt% of the catalyst weight will be added. 2 / g, pore volume 0.95cm 3 / g), 8wt% HZ-1 molecular sieve, and 17wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, cell parameter of 2.468, specific surface area of 743m²). 2 / g, pore volume 0.56cm 3 Mix guar gum powder (1 wt% of the total weight of macroporous alumina and HZ-1 molecular sieve) and a nitric acid aqueous solution (1 wt% by mass concentration), add water, crush into a paste, and extrude into strips. Then dry at 120℃ for 4 h, and calcine at 550℃ for 3 h to obtain a support strip. Load WO3 (20 wt% by weight of catalyst) and NiO (5 wt% by weight) onto the support strip using an equal-volume impregnation method. Add the support strip to a pre-prepared impregnation solution (ammonium metatungstate and nickel nitrate aqueous solution) with an equal volume of water absorbed by the support, let stand for 12 h, dry at 120℃ for 8 h in air atmosphere, and calcine at 450℃ for 4 h to obtain catalyst C-1. The specific properties are shown in Table 2.
[0071] Example 2
[0072] (1) Preparation of HZSM-23 molecular sieve
[0073] 17.43 g of hexamethylenediamine was dissolved in 216 g of deionized water, and then 18 g of fumed silica was added. After stirring at room temperature (25 °C) for 1 h, the mixture was transferred to a 300 mL reactor with a polytetrafluoroethylene liner. The mixture was crystallized at 200 °C for 12 h, then quenched and centrifuged to obtain 18.97 g of solid material.
[0074] Add 37 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at room temperature for 0.5 h at a stirring rate of 150 rpm. Then add 76 mL of 0.01 mol / L NaOH solution to the mixture and carry out a first reaction at 25 °C with stirring for 12 h at a stirring rate of 150 rpm to obtain mixture A. Add 0.9 g of ZSM-23 seed crystals to deionized water to prepare 30 mL of ZSM-23 seed crystal solution, add it to mixture A, and carry out a second reaction at 100 °C with stirring for 20 h at a stirring rate of 300 rpm to obtain material B.
[0075] 0.67 g of Al2(SO4)3·18H2O and 0.85 g of pyrrolidine were added sequentially to 20 mL of deionized water to obtain a clear solution C. Solution C was added to the material B, and after thorough mixing, the final mixture was transferred to a 200 mL reactor lined with polytetrafluoroethylene and crystallized at 200 °C for 36 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain ZSM-23 molecular sieve Z-2.
[0076] The sample was placed in a 0.5 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 50 and stirred continuously in a water bath at 80–90 °C for 1 hour, followed by filtration and washing. This process was repeated twice. The sample was then dried in a 100 °C oven for 8 hours, followed by calcination at 550 °C in air for 3 hours to obtain HZ-2. Specific properties are shown in Table 1.
[0077] (2) Catalyst preparation
[0078] Macroporous alumina (specific surface area 408 m²) accounting for 68 wt% of the catalyst weight was used. 2 / g, pore volume 0.95cm 3 / g), 5wt% HZ-2 molecular sieve, and 12wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, cell parameter of 2.468, specific surface area of 743m²). 2 / g, pore volume 0.54cm 3 Mix guar gum powder (1 wt% of the total weight of macroporous alumina and HZ-2 molecular sieve) and a 1 wt% nitric acid aqueous solution, add water, crush into a paste, and extrude into strips. Then dry at 120℃ for 4 h, and calcine at 550℃ for 3 h to obtain a support strip. Load WO3 (20 wt% of catalyst weight) and NiO (5 wt% of catalyst weight) onto the support strip using an equal-volume impregnation method. Add the support strip to a pre-prepared impregnation solution (ammonium metatungstate and nickel nitrate aqueous solution) with an equal volume of water absorbed by the support, let stand for 12 h, dry at 120℃ for 8 h in air atmosphere, and calcine at 450℃ for 4 h to obtain catalyst C-2. The specific properties are shown in Table 2.
[0079] Example 3
[0080] (1) Preparation of HZSM-23 molecular sieve
[0081] 4.68 g of hexamethylenediamine was dissolved in 54 g of deionized water, and then 6 g of fumed silica was added. After stirring at room temperature (25 °C) for 1 h, the mixture was transferred to a 100 mL reactor with a polytetrafluoroethylene liner. The mixture was crystallized at 170 °C for 24 h, then quenched and centrifuged to obtain 6.34 g of solid material.
[0082] Add 6 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at room temperature for 0.5 h at a stirring rate of 200 rpm. Then add 63 mL of 0.005 mol / L NaOH solution to the mixture and carry out a first reaction at 25 °C with stirring for 6 h at a stirring rate of 200 rpm to obtain mixture A. Add 0.18 g of ZSM-23 seed crystals to deionized water to prepare 10 mL of ZSM-23 seed crystal solution, add it to mixture A, and carry out a second reaction at 80 °C with stirring for 16 h at a stirring rate of 200 rpm to obtain material B.
[0083] 0.17 g of Al2(SO4)3·18H2O and 0.40 g of pyrrolidine were added sequentially to 20 mL of deionized water to obtain a clear solution C. Solution C was added to the material B, and after thorough mixing, the final mixture was transferred to a 150 mL reactor lined with polytetrafluoroethylene and crystallized at 200 °C for 48 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain ZSM-23 molecular sieve Z-3.
[0084] Weigh the Z-3 sample and place it in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 20. Stir continuously in a water bath at 80–90 °C for 1 hour, then filter and wash. Repeat the above operation twice, then dry the sample in a 100 °C oven for 8 hours, and then calcine it in air at 550 °C for 3 hours to obtain HZ-3. The specific properties are shown in Table 1.
[0085] (2) Catalyst preparation
[0086] Macroporous alumina (specific surface area 408 m²) accounting for 62 wt% of the catalyst weight was added. 2 / g, pore volume 0.95cm 3 / g), 4wt% HZ-3 molecular sieve, 10wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, cell parameter of 2.468, specific surface area of 743m²), 2 / g, pore volume 0.54cm 3Mix guar gum powder (1 wt% of the total weight of macroporous alumina and HZ-3 molecular sieve) and a 1 wt% nitric acid aqueous solution, add water, crush into a paste, and extrude into strips. Then dry at 120℃ for 4 h, and calcine at 550℃ for 3 h to obtain a support strip. Load WO3 (20 wt% of catalyst weight) and NiO (4 wt% of catalyst weight) onto the support strip using an equal-volume impregnation method. Add the support strip to a pre-prepared impregnation solution (ammonium metatungstate and nickel nitrate aqueous solution) with an equal volume of water absorbed by the support, let stand for 12 h, dry at 120℃ for 8 h in air atmosphere, and calcine at 450℃ for 4 h to obtain catalyst C-3. The specific properties are shown in Table 2.
[0087] Example 4
[0088] (1) Preparation of HZSM-23 molecular sieve
[0089] 4.68 g of hexamethylenediamine was dissolved in 54 g of deionized water, and then 6 g of fumed silica was added. After stirring at room temperature (25 °C) for 1 h, the mixture was transferred to a 100 mL reactor with a polytetrafluoroethylene liner. The mixture was crystallized at 150 °C for 24 h, then quenched and centrifuged to obtain 6.61 g of solid material.
[0090] Add 3.3 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at room temperature for 0.5 h at a stirring rate of 250 rpm. Then add 30 mL of 0.008 mol / L NaOH solution to the mixture and carry out a first reaction at 25 °C with stirring for 8 h at a stirring rate of 250 rpm to obtain mixture A. Add 0.03 g of ZSM-23 seed crystals to deionized water to prepare 5 mL of ZSM-23 seed crystal solution, add it to mixture A, and carry out a second reaction at 60 °C with stirring for 30 h at a stirring rate of 200 rpm to obtain material B.
[0091] 0.44 g of Al2(SO4)3·18H2O and 0.15 g of pyrrolidine were added sequentially to 15 mL of deionized water to obtain a clear solution C. Solution C was added to the material B, and after thorough mixing, the final mixture was transferred to a 100 mL reactor lined with polytetrafluoroethylene and crystallized at 180 °C for 24 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain ZSM-23 molecular sieve Z-4.
[0092] Weigh the Z-4 sample and place it in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. Stir continuously in a water bath at 80–90 °C for 1 hour, then filter and wash. Repeat the above operation twice, then dry the sample in a 100 °C oven for 8 hours, and then calcine it in air at 550 °C for 3 hours to obtain HZ-4. The specific properties are shown in Table 1.
[0093] (2) Catalyst preparation
[0094] Macroporous alumina (specific surface area 408m²) accounting for 43 wt% of the catalyst weight was added. 2 / g, pore volume 0.95cm 3 / g), 12wt% HZ-4 molecular sieve, and 15wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, cell parameter of 2.468, specific surface area of 743m²). 2 / g, pore volume 0.54cm 3 Mix guar gum powder (1 wt% of the total weight of macroporous alumina and HZ-4 molecular sieve) and a 1 wt% nitric acid aqueous solution, add water, crush into a paste, and extrude into strips. Then dry at 120℃ for 4 h, and calcine at 550℃ for 3 h to obtain a support strip. Load WO3 (25 wt% of catalyst weight) and NiO (5 wt% of catalyst weight) onto the support strip using an equal-volume impregnation method. Add the support strip to a pre-prepared impregnation solution (ammonium metatungstate and nickel nitrate aqueous solution) with an equal volume of water absorbed by the support, let stand for 12 h, dry at 120℃ for 8 h in air atmosphere, and calcine at 450℃ for 4 h to obtain catalyst C-4. The specific properties are shown in Table 2.
[0095] Comparative Example 1
[0096] Compared with Example 1, the difference is that HZSM-23 molecular sieve was prepared according to the preparation method of patent CN109516471A. In the 2,6-dimethylpyridine infrared Brønsted acid of the obtained HZSM-23 molecular sieve, the proportion of weak Brønsted acid was 49.8%, and the other conditions were the same as in Example 1. The details are as follows.
[0097] (1) Preparation of HZSM-23 molecular sieve according to patent CN109516471A
[0098] 0.079 g NaOH, 0.163 g Al2(SO4)3·18H2O, 0.438 g pyrrolidine, and 1.48 g fumed silica were sequentially dissolved in 20.0 g deionized water and thoroughly mixed to obtain gel A. The molar ratio of each component was SiO2 in the silicon source: Al2O3 in the aluminum source: PY: NaOH: H2O = 1:0.01:0.25:0.083:45. Gel A was heated in a 180℃ constant temperature oven for 12 h and then cooled to room temperature. 0.119 g NaOH, 0.489 g... Al2(SO4)3·18H2O and 2.22g of fumed silica were dissolved sequentially in 30.0g of deionized water and stirred until homogeneous to obtain gel B. The molar ratio of the components was SiO2 in the silicon source: Al2O3 in the aluminum source: NaOH:H2O = 1:0.02:0.083:45. Gel B was added to gel A and mechanically stirred for 1h to obtain a uniform white gel. This gel was transferred to a 100mL hydrothermal reactor and crystallized at 180℃ for 44h. The resulting product was then filtered, washed, and dried at 65℃ for 24h to obtain ZSM-23 molecular sieve DZ-1.
[0099] Weigh the DZ-1 sample and place it in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. Stir continuously in a water bath at 80–90 °C for 1 hour, then filter and wash. Repeat the above operation twice, then dry the sample in a 100 °C oven for 8 hours, and then calcine it in air at 550 °C for 3 hours to obtain HDZ-1. The specific properties are shown in Table 1.
[0100] (2) Catalyst preparation
[0101] Macroporous alumina (specific surface area 408m²) accounting for 50wt% of the catalyst weight will be added. 2 / g, pore volume 0.95cm 3 / g), 8wt% HDZ-1 molecular sieve, and 17wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, cell parameter of 2.468, specific surface area of 743m²). 2 / g, pore volume 0.56cm 3 A mixture of guar gum powder (1 wt% of the total weight of macroporous alumina and HDZ-1 molecular sieve) and a 1 wt% nitric acid aqueous solution was prepared, water was added, and the mixture was pressed into a paste and extruded into strips. The paste was then dried at 120℃ for 4 hours and calcined at 550℃ for 3 hours to obtain a support strip. WO3 (20 wt% of catalyst weight) and NiO (5 wt% of catalyst weight) were loaded onto the support strip using an equal-volume impregnation method. The support strip was then added to a pre-prepared impregnation solution (ammonium metatungstate and nickel nitrate aqueous solution) with an equal volume of water absorption. After standing for 12 hours, the mixture was dried at 120℃ for 8 hours in air and then calcined at 450℃ for 4 hours to obtain catalyst DC-1. Specific properties are shown in Table 2.
[0102] Comparative Example 2
[0103] Compared with Example 1, the difference is that oleylamine was not added during the preparation of HZSM-23 molecular sieve. In the 2,6-dimethylpyridine infrared Brønsted acid of the obtained HZSM-23 molecular sieve, the proportion of weak Brønsted acid was 52.3%, and the other conditions were the same as in Example 1. The HZSM-23 molecular sieve was HDZ-2, and its specific properties are shown in Table 1; the corresponding catalyst was DC-2, and its specific properties are shown in Table 2.
[0104] Table 1 Properties of HZSM-23 Molecular Sieves
[0105]
[0106] Table 2 Catalyst Properties
[0107]
[0108] The catalysts of the above examples and comparative examples were subjected to activity evaluation tests. The evaluation conditions were: total reaction pressure 8.0 MPa, hydrogen-to-oil volume ratio 800:1, and liquid hourly space velocity 1.0 h⁻¹. -1 The properties of the feedstock are shown in Table 3. The catalyst performance test results are shown in Table 4 for the same conversion rate.
[0109] Table 3 Properties of Feed Oil
[0110] crude oil urging firewood <![CDATA[Density (20 °C), g / cm 3 > 0.919 Distillation range, °C IBP / EBP 189 / 384 Pour point, ℃ 4 S, μg / g 608 N, μg / g 1357 cetane number 19 Cycloalkanes content, wt% 54 Aromatic content, wt% 28
[0111] Table 4 Catalyst Reaction Performance Results
[0112] catalyst C-1 C-2 C-3 C-4 DC-1 DC-2 reaction temperature 365 366 367 363 361 361 >180℃ diesel Yield, wt% 97.4 97.3 97.0 97.2 91.4 91.8 cetane number 52.8 52.6 52.2 53.5 48.6 48.9 Pour point, ℃ -28 -27 -25 -29 -14 -15
[0113] As can be seen from the reaction results in Table 4, the catalyst described in this invention produces better diesel yield and quality than the reference catalyst under the same process conditions.
Claims
1. A catalyst for diesel hydrotreating, characterized in that: Based on the weight of the catalyst, it includes the following components: a) HZSM-23 molecular sieve, with a content of 2~13 wt%, preferably 4~12 wt%; b) Modified Y molecular sieve, with a content of 3~20 wt%, preferably 5~18 wt%; c) Macroporous alumina, with a content of 30-65 wt%, preferably 35-60 wt%; d) The hydrogenation active component is selected from Group VIB metals and / or Group VIII metals, wherein the content of Group VIB metals as oxides is 10-30 wt%, preferably 12-25 wt%, and the content of Group VIII metals as oxides is 2-10 wt%, preferably 3-8 wt%. In the 2,6-dimethylpyridine infrared Brønsted acid of the catalyst, the proportion of weak Brønsted acid is 48% to 74%, preferably 50% to 72%.
2. The catalyst according to claim 1, characterized in that: The catalyst has a total Brønsted acid content of 2,6-dimethylpyridine in infrared spectroscopy of 0.071~0.239 mmol / g, preferably 0.080~0.227 mmol / g.
3. The catalyst according to claim 1, characterized in that: The total Brønsted acid content of the catalyst in infrared spectroscopy is 0.125~0.310 mmol / g, preferably 0.134~0.295 mmol / g; preferably, the ratio of the total Brønsted acid content of 2,6-dimethylpyridine in infrared spectroscopy to the total Brønsted acid content of pyridine in infrared spectroscopy is 35~77:100, more preferably 37~75:
100.
4. The catalyst according to claim 1, characterized in that: The modified Y molecular sieve has the following properties: SiO2 / Al2O3 molar ratio of 20-40, cell parameter of 2.464-2.469, and specific surface area of 730-840 m². 2 / g, pore volume 0.40~0.56cm³ 3 / g.
5. The catalyst according to claim 1, characterized in that: The macroporous alumina has the following properties: specific surface area of 375~450 m². 2 / g, pore volume 0.74~1.15 cm³ 3 / g; preferably, specific surface area is 390~430 m² 2 / g, pore volume 0.78~1.10 cm³ 3 / g.
6. The catalyst according to claim 1, characterized in that: In the hydrogenation active component, the Group VIB metal is tungsten and / or molybdenum, and the Group VIII metal is nickel and / or cobalt.
7. The method for preparing the diesel hydrotreating catalyst according to any one of claims 1-6, characterized in that: The method includes the following: (1) HZSM-23 molecular sieve, modified Y molecular sieve, macroporous alumina and binder are mixed, shaped, dried and calcined to obtain a carrier; in the 2,6-dimethylpyridine infrared Brønsted acid of the HZSM-23 molecular sieve, the proportion of weak Brønsted acid is 64%~95%, preferably 67%~93%; (2) The carrier obtained in step (2) is impregnated with a solution containing hydrogenation active components, and then dried and calcined to obtain a diesel hydrotreating catalyst.
8. The preparation method according to claim 7, characterized in that: The 2,6-dimethylpyridine total Brønsted acid content of the HZSM-23 molecular sieve in step (1) is 0.114~0.249 mmol / g, preferably 0.125~0.236 mmol / g.
9. The preparation method according to claim 7, characterized in that: The total β-carboxylic acid content of pyridine in the HZSM-23 molecular sieve in step (1) is 0.143~0.398 mmol / g, preferably 0.158~0.380 mmol / g; the ratio of the total β-carboxylic acid content of 2,6-dimethylpyridine to the total β-carboxylic acid content of pyridine in the infrared is 65~96:100, preferably 69~93:
100.
10. The preparation method according to claim 7, characterized in that: The adhesive used in step (1) is one or more of nitric acid, guar gum powder, methylcellulose, and polyacrylamide, preferably nitric acid and / or guar gum powder.
11. The preparation method according to claim 7, characterized in that: The molding process described in step (1) can be performed by any one of extrusion, sheeting, or pelletizing, with extrusion being the preferred method.
12. The preparation method according to claim 7, characterized in that: The drying and calcining conditions described in step (1) are as follows: the drying temperature is 60~130 ℃ and the time is 2~12 h, preferably the drying temperature is 80~120 ℃ and the time is 4~8 h; the calcining temperature is 500~600 ℃ and the time is 2~8 h, preferably the calcining temperature is 530~570 ℃ and the time is 3~6 h.
13. The preparation method according to claim 7, characterized in that: In step (2), the active hydrogenation component is selected from Group VIB metals and / or Group VIII metals, wherein the Group VIB metals are preferably tungsten and / or molybdenum, and the Group VIII metals are preferably nickel and / or cobalt.
14. The preparation method according to claim 7, characterized in that: The impregnation in step (2) is performed using either saturated impregnation or supersaturated impregnation, preferably saturated impregnation.
15. The preparation method according to claim 7, characterized in that: The drying and calcination conditions in step (2) are as follows: drying at 80~120 ℃ for 4~12 h, and calcining at 400~700 ℃ for 3~12 h.
16. The application of the diesel hydrotreating catalyst according to any one of claims 1-6 in the diesel hydrotreating process.
17. The application according to claim 16, characterized in that: The total mass content of aromatics and cycloalkanes in the diesel fuel is 50-90%, preferably 55-86%; wherein, the mass content of aromatics is 10-40%, preferably 15-34%; and the mass content of cycloalkanes is 30-82%, preferably 35-71%.
18. The application according to claim 16, characterized in that: The diesel fuel has the following properties: a distillation range of 180–400℃, a sulfur content of 300–800 ppm, and a nitrogen content of 1000–1500 ppm.
19. The application according to claim 16, characterized in that: The reaction conditions for the diesel hydrotreating process are as follows: reaction temperature 350~400 ℃, total reaction pressure 5.0~10.0 MPa, and liquid hourly space velocity 0.5~3 h⁻¹. -1 The hydrogen-to-oil volume ratio is 400:1 to 1000:1.