A phosphorus-rich transition metal phosphide catalyst, a synthesis method and application thereof
By synthesizing phosphorus-rich transition metal phosphide catalysts under mild conditions, the problems of high energy consumption and high cost in existing technologies have been solved, achieving efficient hydrodenitrogenation of cracked gasoline and reducing preparation costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-09
- Publication Date
- 2026-07-24
AI Technical Summary
In the existing technology, the synthesis method of phosphorus-rich transition metal phosphide catalysts requires high energy input and long reaction time, and it is difficult to achieve both activity and aromatic hydrogenation saturation in the hydrodenitrogenation process of cracked gasoline, resulting in high preparation cost.
A phosphorus-rich transition metal phosphide catalyst was synthesized by using anhydrous transition metal halides and a phosphorus source under relatively mild conditions. The catalyst, with a particle size of 40-100 nm, was prepared through steps such as drying, grinding, molding, and heating reaction. It was then used for the hydrodenitrogenation reaction of cracked gasoline.
It achieves hydrodenitrogenation with high activity and low aromatic hydrogenation saturation, and the preparation process is simple, low-cost, and has high catalyst purity, making it suitable for hydrodenitrogenation treatment of cracked gasoline.
Smart Images
Figure CN117861693B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalytic technology for hydrodenitrogenation of cracked gasoline, and in particular to a phosphorus-rich transition metal phosphide catalyst, its synthesis method, and its application. Background Technology
[0002] Cracked gasoline, primarily composed of C5-C9 hydrocarbons, is a key byproduct of naphtha cracking to ethylene production. Due to its high aromatic content, it is typically used as a feedstock for downstream aromatics extraction. In recent years, feedstock oils have shown a trend towards heavier processing, resulting in a significant increase in nitrogen content. However, since nitrogen compounds are toxic to the hydrodesulfurization (HDS) process and basic nitrogen compounds cannot be removed during aromatics extraction, cracked gasoline requires hydrodenitrogenation (HDN) treatment. Therefore, research on the HDN catalytic process and related technologies for cracked gasoline is extremely important for improving aromatics extraction efficiency.
[0003] The HDN process in cracked gasoline is particularly representative due to the difficulty in removing basic nitrogen from pyridine. In recent years, researchers have discovered that transition metal phosphide catalysts exhibit high HDN activity. Compared to sulfides, Group VI phosphides show superior activity. Compared to noble metal catalysts, transition metal phosphide catalysts also demonstrate better HDN performance. Therefore, transition metal phosphide catalysts offer the advantage of combining low cost with superior HDN performance, showing great application potential. Previous research has mainly focused on phosphorus-poor transition metal phosphides, while studies on general synthesis methods and HDN performance of phosphorus-rich transition metal phosphide catalysts in HDN systems are limited. This is primarily because the synthesis of phosphorus-rich transition metal phosphides typically requires significant energy input and long reaction times, such as under harsh conditions like high temperatures (800–1200℃) or high-energy ball milling / high-energy bonding. Therefore, developing a more universal synthesis method for phosphorus-rich transition metal phosphide catalysts and studying their HDN catalytic performance is extremely necessary. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a phosphorus-rich transition metal phosphide catalyst, its synthesis method, and its application. The catalyst of this invention has a high phosphorus content and is used in the hydrodenitrogenation reaction of cracked gasoline. It exhibits high activity, low aromatic ring hydrogenation saturation, low preparation cost, and a relatively simple and controllable process.
[0005] The first aspect of the present invention provides a phosphorus-rich transition metal phosphide catalyst, wherein the phosphorus-rich transition metal phosphide has the chemical formula MP2 and / or MP3, and the transition metal M is selected from at least one element of Group VIII and / or Group IB.
[0006] Furthermore, the Group VIII element is selected from at least one of Fe, Co, and Ni, and the Group IB element is selected from Cu.
[0007] Furthermore, the phosphorus-rich transition metal phosphide is a nanoparticle with a particle size of 40–100 nm, preferably 40–90 nm.
[0008] Furthermore, the phosphorus-rich transition metal phosphides have various crystal systems, including orthorhombic FeP2, cubic CoP3 and NiP2, and monoclinic CuP2.
[0009] Furthermore, the relative crystallinity of the phosphorus-rich transition metal phosphide exceeds 90%, for example, 91% to 100% (with the crystallinity of the standard sample being 100%).
[0010] A second aspect of this invention provides a method for preparing a phosphorus-rich transition metal phosphide catalyst, comprising:
[0011] (1) Dry, cool, grind, shape and place the anhydrous transition metal halide in a reactor;
[0012] (2) Place the phosphorus source in the reactor described above and seal the reactor;
[0013] (3) The reactor is heated to carry out the reaction, and then cooled after the reaction is completed to obtain a phosphorus-rich transition metal phosphide catalyst.
[0014] Further, in step (1), the anhydrous transition metal halide is selected from at least one of FeCl2, CoCl2, NiCl2 and CuCl2.
[0015] Further, in step (1), the drying is carried out under high temperature dynamic vacuum conditions. The specific drying conditions include drying at 200-300℃ for 3-6 hours, preferably heating to 200-300℃ at a rate of 0.5-2℃ / min and then drying for 3-6 hours.
[0016] Furthermore, in step (1), the cooling is cooling to room temperature.
[0017] Furthermore, in step (1), the grinding and shaping can be performed using conventional methods in the art. For example, after cooling, the anhydrous transition metal halide can be transferred to a glove box for thorough grinding, such as using an agate mortar and pestle. After grinding, it can be pressed into shape using a hand-held pressing mold, such as pressing it into a sheet or cylinder, preferably a cylinder, with a diameter of 5-9 mm and a thickness of 2-3 mm.
[0018] Furthermore, in step (1), the reactor can be an ampoule, which is single-ended and made of Pyrex or quartz, preferably quartz.
[0019] Furthermore, in step (2), the phosphorus source is red phosphorus (P) or white phosphorus (P4), with red phosphorus being preferred.
[0020] Furthermore, in step (2), the phosphorus source is first treated under a vacuum atmosphere. Specifically, the treatment method includes treating the phosphorus source under a vacuum of 50–100 Pa for 5–20 minutes. For example, this can be carried out in a Schlenck flask.
[0021] Further, in steps (1) and (2), the molar ratio of the anhydrous transition metal halide to the phosphorus source is 1:(2.5-3) when the anhydrous transition metal halide is selected from at least one of FeCl2, NiCl2 and CuCl2; and 1:(3.5-4) when the anhydrous transition metal halide is selected from CoCl2.
[0022] Furthermore, in step (2), the sealing can be carried out using a suitable method for the corresponding reactor. For example, when using ampoules, the sealing method is methane-oxygen torch sealing or acetylene-oxygen torch sealing, preferably methane-oxygen torch sealing.
[0023] Furthermore, in step (2), it is preferable that the metal halide and the phosphorus source are placed at opposite ends of the reactor, rather than being mixed evenly.
[0024] Further, in step (3), the heating is performed at 500–700°C for 30–50 hours. Preferably, the temperature is increased to 500–700°C at a rate of 0.5–4°C / min and held for 30–50 hours, and more preferably, the temperature is increased to 600–700°C at a rate of 0.5–1.5°C / min and held for 35–50 hours.
[0025] Furthermore, in step (3), the cooling is cooling to room temperature. When an ampoule is used as the reactor, the cooling process is preferably performed by placing the empty end of the ampoule at the end of the tubular furnace cooler for cooling.
[0026] Further, in step (3), the cooled reactor is opened under an inert atmosphere to obtain a phosphorus-rich transition metal phosphide catalyst, which is then stored in an organic solvent for later use.
[0027] Furthermore, the inert atmosphere may be Ar and / or He, with Ar being preferred.
[0028] Furthermore, the organic solvent may be at least one of cyclohexane, benzene, toluene, and xylene, preferably toluene.
[0029] The third aspect of this invention provides the application of the above-mentioned phosphorus-rich transition metal phosphide catalyst in the hydrodenitrogenation reaction of cracked gasoline.
[0030] Furthermore, the reaction conditions for the hydrodenitrification reaction are as follows: reaction temperature of 230–350 °C, reaction pressure of 2.5–3.5 MPa, and volume hourly space velocity of 0.5–4.0 h⁻¹. -1 The hydrogen / oil volume ratio is 500–600.
[0031] Compared with the prior art, the present invention has the following advantages:
[0032] 1. The catalyst provided by this invention is mainly composed of phosphorus-rich transition metal phosphides with high phosphorus content. The chemical formula of the phosphorus-rich transition metal phosphides is MP2 and / or MP3, and the particle size is 40-100 nm. It is used for the hydrodenitrogenation reaction of cracked gasoline and has the characteristics of high activity and low aromatic hydrogenation saturation.
[0033] 2. The catalyst preparation method provided by this invention does not require solvents in the entire preparation process. It utilizes anhydrous transition metal halides to react with elemental phosphorus sources. The resulting phosphorus-rich transition metal phosphides are not only low in preparation cost, but also relatively simple, controllable, and free of impurities.
[0034] 3. The catalyst provided by this invention exhibits outstanding catalytic performance in the hydrodenitrogenation reaction of cracked gasoline, including high conversion rate and low aromatic hydrogenation saturation. Attached Figure Description
[0035] Figure 1 The XRD patterns are those of the catalysts in Examples 6, 7, 8 and 9, and the corresponding standard samples. Detailed Implementation
[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and do not constitute any limitation thereof. The invention has been described with reference to exemplary embodiments, but it should be understood that the terms used are descriptive and explanatory, not limiting. Modifications and revisions can be made to the invention within the scope of the claims as specified herein, without departing from the scope and spirit of the invention. Although the invention described herein relates to specific methods, materials, and embodiments, it does not imply that the invention is limited to the specific examples disclosed herein; on the contrary, the invention can be extended to all other methods and applications with the same function.
[0037] In the context of this specification, X-ray diffraction (XRD) analysis of the catalyst was performed on a Rigaku D / max-2200PC X-ray diffractometer, using Cu Kα radiation, tube voltage 40 kV, tube current 30 mA, scan rate 10° / min, and scan range 10°–80°.
[0038] In the context of this specification, particle size is calculated using the Scherrer formula. Crystallinity is obtained by Rietveld refinement of the XRD patterns.
[0039]
Example 1
[0040] NiCl2 was dried under dynamic vacuum at 250℃ for 4 hours and stored in an argon-filled glove box. The metal dichloride was ground in the glove box using an agate mortar and pestle. 1.3g of the dried NiCl2 solid was taken and placed into a hand-held tableting mold assembly, pressed into cylindrical granules (8mm in diameter, 2-3mm thick), and weighed. The granules were then transferred to the sealed end of a single-sided sealed ampoule for later use.
[0041] Weigh 0.78 g of red phosphorus into a Schlenk flask, evacuate it for 5 min, and then transfer it to a glove box filled with argon. Remove the flake-shaped solid red phosphorus from the Schlenk flask and transfer it to the aforementioned ampoule, then seal the ampoule with a methane-oxygen torch. Gently shake the sealed ampoule to ensure that the metal halide and phosphorus source are located at opposite ends of the ampoule.
[0042] The ampoule was placed in the center of the isothermal section of a tube furnace and heated to 500°C at a rate of 2°C / min and held for 30 hours. Then, the empty end of the ampoule was placed at the cooler end of the tube furnace. After cooling for 30 minutes, the ampoule was opened under an Ar atmosphere to obtain phosphorus-rich transition metal phosphide (NiP2) solid, which was stored in toluene for later use.
[0043]
Example 2
[0044] The catalyst preparation method is the same as in [Example 1], except that instead of drying NiCl2 under dynamic vacuum at 250°C for 4 hours, NiCl2 is dried under dynamic vacuum at 200°C for 4 hours; the final catalyst SS2 is obtained.
[0045]
Example 3
[0046] The catalyst preparation method is the same as in [Example 1], except that instead of drying NiCl2 under dynamic vacuum at 250°C for 4 hours, NiCl2 is dried under dynamic vacuum at 300°C for 4 hours; the final catalyst SS3 is obtained.
[0047]
Example 4
[0048] The catalyst preparation method is the same as in [Example 1], except that the selected phosphorus source is changed from red phosphorus to white phosphorus, and the final catalyst SS4 is obtained; note that, for safety reasons, liquid nitrogen is used for cooling during the transportation process to prevent the sublimation of white phosphorus.
[0049]
Example 5
[0050] The catalyst preparation method is the same as in [Example 1], except that the mass of red phosphorus used is changed from 0.78g to 0.83g, and the final catalyst SS5 is obtained.
[0051]
Example 6
[0052] The catalyst preparation method is the same as in [Example 5], except that the heating program in the tube furnace was changed from a rate of 2℃ / min to 500℃ and held for 30h to a rate of 1℃ / min to 600℃ and held for 40h, finally yielding catalyst SS6.
[0053]
Example 7
[0054] The catalyst preparation method is the same as in [Example 6], except that the metal halide is changed from NiCl2 to CuCl2, and the final catalyst SS7 is obtained.
[0055]
Example 8
[0056] The catalyst preparation method is the same as in [Example 6], except that the metal halide is changed from NiCl2 to FeCl2, and the final catalyst SS8 is obtained.
[0057]
Example 9
[0058] The catalyst preparation method is the same as in [Example 6], except that the metal halide is changed from NiCl2 to CoCl2, and the final catalyst SS9 is obtained.
[0059]
Example 10
[0060] The catalyst preparation method is the same as in [Example 1], except that the mass of red phosphorus used is changed from 0.78g to 1.16g, and the final catalyst SS10 is obtained.
[0061]
Comparative Example 1
[0062] Weigh 7.8 g of Ni(NO3)2·6H2O and 7.2 g of (NH4)2HPO4, dissolve them in 30 mL of distilled water, add 1.0 mL of dilute nitric acid until the solution is clear, stir for 8 h, let stand for aging for 8 h, dry overnight at 120 °C, and calcine at 5 °C / min to 500 °C for 3 h. Then transfer to a tube furnace for programmed temperature reduction of the catalyst precursor: in a hydrogen flow of 100 mL / min, increase to 600 °C at 2 °C / min and hold for 2 h. After natural cooling to room temperature, passivate the surface by introducing 0.5–1 vol.% O2 / N2 mixed gas for 2–3 h. Catalyst BJ1 is obtained.
[0063] [Comparative Example 2]
[0064] At room temperature, 1.17 g of ammonium molybdate tetrahydrate ((NH4)6Mo7O) 24• 4H₂O) was dissolved in 5 mL of H₂O, stirred thoroughly to dissolve, and then dried overnight at 100°C, followed by calcination at 5°C / min to 500°C for 3 hours. Then, a pre-sulfurization process was performed: sulfides were prepared using solvents to achieve a sulfur content of 400–3000 ppm in the sulfurized oil; hydrogen gas was introduced at a pressure of 2.6–3.0 MPa, with a hydrogen to catalyst volume ratio of (10–100):1; the catalyst bed was heated to 160–180°C, and sulfurized oil was introduced at a space velocity of 3.0–5.0 h⁻¹. -1 Continue heating the catalyst bed to 280-320°C at a rate of 30°C / h, maintain the temperature for 20-40 hours, then allow it to cool naturally to 220-230°C. Stop feeding the sulfiding oil, and the sulfidation process is complete, yielding catalyst BJ2.
[0065] [Comparative Example 3]
[0066] The catalyst preparation method is the same as in [Example 6], except that the molar ratio of transition metal halide to phosphorus source is 1:4.5, and the final catalyst is BJ3.
[0067]
Example 11
[0068] For the catalysts of Examples 1-10, 1.0 g was weighed and charged into a fixed-bed reactor. The inlet temperature was 240°C, the pressure was 2.5 MPa, the hydrogen / oil volume ratio was 600:1, and the fresh oil space velocity was 2.0 h⁻¹. -1 Under the reaction conditions, a simulated nitrogen- and sulfur-containing cracked gasoline component (a mixed solution of 30 ppm pyridine, 300 ppm thiophene, and BTX, with a benzene:toluene:xylene molar ratio of 30:40:30 in BTX) underwent HDN reaction. The denitrification, desulfurization rates, and aromatic hydrogenation saturation rates during the reaction were analyzed. The results are shown in Table 1.
[0069] [Comparative Example 4]
[0070] The catalysts from Comparative Examples 1-3 were weighed out in batches of 1.0 g and charged into fixed-bed reactors. The inlet temperature was 240 °C, the pressure was 2.5 MPa, the hydrogen / oil volume ratio was 600:1, and the fresh oil space velocity was 2.0 h⁻¹. -1 Under the reaction conditions, a simulated nitrogen- and sulfur-containing cracked gasoline component (a mixed solution of 30 ppm pyridine, 300 ppm thiophene, and BTX, with a benzene:toluene:xylene molar ratio of 30:40:30 in BTX) underwent HDN reaction. The denitrification, desulfurization rates, and aromatic hydrogenation saturation rates during the reaction were analyzed. The results are shown in Table 1.
[0071] Table 1 Catalyst composition and catalytic performance of examples and comparative examples
[0072]
[0073]
[0074] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. The application of a phosphorus-rich transition metal phosphide catalyst in the hydrodenitrogenation reaction of cracked gasoline, characterized in that, The phosphorus-rich transition metal phosphide has the chemical formula MP2 and / or MP3, and the transition metal M is selected from at least one element in Group VIII and / or Group IB; the relative crystallinity of the phosphorus-rich transition metal phosphide exceeds 90%; the phosphorus-rich transition metal phosphide is a nanoparticle with a particle size of 40~100nm. The Group VIII element is selected from at least one of Fe, Co, and Ni, and the Group IB element is selected from Cu; The phosphorus-rich transition metal phosphides have crystal structures including at least one of the following: orthorhombic FeP2, cubic CoP3 and NiP2, and monoclinic CuP2.
2. The application according to claim 1, characterized in that, The preparation method of the phosphorus-rich transition metal phosphide catalyst includes: (1) The anhydrous transition metal halide is dried, cooled, ground, shaped, and placed in a reactor, wherein the reactor is an ampoule and the ampoule is single-end sealed; (2) Place the phosphorus source in the above reactor and seal the reactor, wherein the metal halide and the phosphorus source are placed at opposite ends of the reactor; (3) The reactor is heated to carry out the reaction. The heating is carried out at 500-700°C for 30-50 hours. After the reaction is completed, the reactor is cooled to obtain a phosphorus-rich transition metal phosphide catalyst.
3. The application according to claim 2, characterized in that, In step (1), the anhydrous transition metal halide is selected from at least one of FeCl2, CoCl2, NiCl2 and CuCl2.
4. The application according to claim 2, characterized in that, In step (1), the drying is carried out under high temperature dynamic vacuum conditions. The specific drying conditions include drying at 200~300℃ for 3~6 hours.
5. The application according to claim 4, characterized in that, In step (1), the temperature is increased to the required drying temperature at a rate of 0.5~2℃ / min.
6. The application according to claim 2, characterized in that, In step (2), the phosphorus source is red phosphorus or white phosphorus; and / or, In step (2), the phosphorus source is first treated under a vacuum atmosphere. The specific treatment method includes treating the phosphorus source for 5 to 20 minutes under a vacuum of 50 to 100 Pa.
7. The application according to claim 3, characterized in that, When the anhydrous transition metal halide is selected from at least one of FeCl2, NiCl2 and CuCl2, the molar ratio of the anhydrous transition metal halide to the phosphorus source is 1:(2.5~3); when the anhydrous transition metal halide is selected from CoCl2, the molar ratio of the anhydrous transition metal halide to the phosphorus source is 1:(3.5~4).
8. The application according to claim 2, characterized in that, In step (3), the temperature is increased to the required reaction temperature at a rate of 0.5~4℃ / min.