CN116809123A - Natural gas hydrodesulfurization catalyst and preparation method thereof - Google Patents

Abstract

Natural gas hydrodesulfurization catalyst and its preparation method, belonging to the field of hydrodesulfurization, the carrier is a metal organic framework material MIL‑101 (Cr), the active component is a mixture of molybdenum and cobalt, and the cocatalyst component c is B, F, P , Si, Mn, Ca and Zn are mixed, and the element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c = (2～5): 10 : (1～5). The present invention can maintain a high conversion rate of organic sulfur in natural gas at a relatively high space speed, thereby greatly increasing the processing capacity of the natural gas hydrodesulfurization process per unit time. It can not only effectively improve the quality of natural gas, but also strengthen environmental protection. The protection also helps enterprises reduce production costs and improve production efficiency.

Description

Natural gas hydrodesulfurization catalyst and preparation method thereof

Technical field

The present invention relates to a catalyst used in the field of hydrodesulfurization, specifically a natural gas hydrodesulfurization catalyst and a preparation method thereof.

Background technique

In recent years, petroleum resources have become increasingly scarce, and coal chemical industry has stagnated due to environmental issues, safety issues, and energy consumption issues. As the demand for clean energy grows, natural gas accounts for an increasing proportion in chemical production and energy structure. Come bigger. The main component of natural gas is methane. Natural gas from underground reservoirs usually contains acidic groups such as H ₂ S, CO2 and organic sulfides (RSH, COS, RSSR, R'SR and C ₄ H ₄ S) to varying degrees. point. When natural gas is used as a chemical raw material, these acidic components can also cause catalyst poisoning, and can cause equipment and pipeline corrosion during mining, gathering, transportation, and processing. Therefore, natural gas desulfurization is of great significance.

The inorganic sulfur in natural gas is mainly H ₂ S, which can be removed with zinc oxide desulfurizer. However, organic sulfur (carbonyl sulfide, mercaptan, thioether, etc.) is usually converted into H ₂ S by hydrogenation catalysis. Then use desulfurizers such as zinc oxide for removal. GB 17820-2018 "Natural Gas" promulgated and implemented in 2018 has stricter requirements for the total sulfur content in the commercial gas of natural gas purification plants. China's mid- and long-term goal is to control total sulfur to 8 mg/m ^3. The introduction of this standard also provides a new opportunity for natural gas purification. The upgrade of plant desulfurization technology has brought great opportunities and challenges.

The active components of traditional natural gas hydrodesulfurization catalysts are Co-Mo, Ni-Mo, and Ni-W. The prepared oxidation state catalyst needs to be sulfurized before HDS reaction. Porous inorganic oxides are generally used as carriers, usually one or more of alumina, silica, zirconium dioxide, and aluminosilicates. The carrier has two main functions in the hydrodesulfurization reaction. One is to load the active metal, and the other is to provide a reaction space to fully contact and react the active metal with the impurities that need to be removed, thereby achieving deep desulfurization and denitrification. This requires the carrier to have a considerable specific surface area, pore volume and a certain mechanical strength, so that impurity molecules can fully react with the active metal through the carrier pores during a long-term production reaction. If the pore size of the carrier is too small, it will produce greater resistance to the mass transfer process, which is not conducive to the effective progress of the reaction and reduces the catalyst activity. However, the carrier not only plays the role of carrying the active component, but also interacts with the active component, sometimes even strongly. Under the influence of this interaction, the performance of the active component will change greatly. Thereby affecting the catalytic activity of the catalyst.

Conventional organic sulfur hydrogenation catalysts use low space velocities and low organic sulfur conversion rates, making it impossible to achieve efficient utilization of the catalyst and miniaturization of equipment. Therefore, it is necessary to increase the specific surface area of the hydrogenation catalyst and increase the contact area between organic sulfur and the active components of the catalyst, so as to achieve the purpose of increasing the space velocity of the hydrodesulfurization reaction and improving the production capacity of the equipment while ensuring the catalyst utilization rate.

Metal-organic framework materials MOFs are a class of materials developed in recent years that are composed of an inorganic metal center and organic functional groups in polydentate organic ligands of aromatic acids or bases that are connected to each other through covalent bonds or ionic bonds, and have a regular pore structure. New porous crystal materials, also known as porous coordination polymers. MOFs can control the porosity of materials by adjusting organic ligands. This can be achieved by designing and synthesizing organic ligands with suitable structures and molecular shapes, so that MOFs can exert optimal performance in applications, such as various separation processes and selection processes. form selective catalysis. Compared with activated carbon and molecular sieves, metal organic framework materials have the advantages of large specific surface area, large porosity and adjustable pore size. The adjustable pore size and high porosity make it an ideal carrier for catalysts, using MOFs. Nanocavities serve as carriers, and physical and chemical methods such as adsorption, impregnation, and precipitation are used to load active components onto the surface or pores of MOFs, which can introduce rich catalytic active sites and allow reactions to proceed within the MOFs cavity.

As we all know, the catalytic performance of a catalyst is not only affected by the carrier, but also by the active ingredients and additives. Currently, there are many kinds of active ingredients and additives used in the field of desulfurization catalysts. How to choose the appropriate carrier and active ingredients? Ingredients and additives to achieve a better catalytic effect are the continued research directions of those skilled in the field.

Contents of the invention

The purpose of the present invention is to provide a natural gas hydrodesulfurization catalyst and a preparation method thereof, by optimizing the types and proportions of carriers, active components and co-catalyst components, thereby achieving better catalytic effects and effectively increasing the service life of the catalyst. .

The technical solution adopted by the present invention to achieve the above technical objectives is: a natural gas hydrodesulfurization catalyst, which is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal-organic framework material MIL-101 (Cr ), its mass content accounts for 20-40% of the total amount of the catalyst, the active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 50-70% of the total amount of the catalyst, and the cocatalyst component c is B , F, P, Si, Mn, Ca, and Zn are mixed, and their mass content accounts for 1-10% of the total amount of the catalyst, and the active component cobalt, the active component molybdenum, and the cocatalyst component c Element molar ratio n _Co : n _Mo : n _c = (2～5): 10: (1～5).

As an optimization solution for the above natural gas hydrodesulfurization catalyst, the cocatalyst component c is a mixture of two of B, F, P, Si, Mn, Ca, and Zn, preferably a mixture of Zn and Mn, B and A mixture of Ca, a mixture of F and P, a mixture of B and Si.

As another optimization solution for the above-mentioned natural gas hydrodesulfurization catalyst, the mass content of the carrier a accounts for 25-35% of the total amount of the catalyst, the mass content of the active component b accounts for 55-65% of the total amount of the catalyst, and the cocatalyst The mass content of component c is 5-8% of the total amount of catalyst.

As another optimization solution for the above-mentioned natural gas hydrodesulfurization catalyst, the element molar ratio of the active component cobalt, active component molybdenum and co-catalyst component c n _Co : n _Mo : n _c = (3～4): 10: (3～4).

As another optimization solution for the above-mentioned natural gas hydrodesulfurization catalyst, the preparation method of the metal-organic framework material MIL-101 (Cr) is as follows:

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1: (4.64~4.93) to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 100 to 200°C for 1 to 24 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal-organic framework material MIL-101 (Cr).

As another optimization solution for the above-mentioned natural gas hydrodesulfurization catalyst, in step ②, after adding hydrofluoric acid to the buffer solution, the reaction is carried out at 150-180°C for 5-9 hours.

As another optimization solution for the above-mentioned natural gas hydrodesulfurization catalyst, in step ④, the vacuum drying temperature is 80-150°C, preferably 90-120°C, and the drying time is 1-50h, preferably 5-20h.

As another optimization solution for the above natural gas hydrodesulfurization catalyst, the metal organic framework material MIL-101 (Cr) has a specific surface area of 100 to 6000 m ² /g, preferably 1000 to 4500 m ² /g, and a pore volume of 0.01 ~5mL/g, preferably 0.1 ~ 2mL/g.

In the preparation method of a natural gas hydrodesulfurization catalyst, the active component b and the cocatalyst component c are respectively impregnated into the carrier a, dried and roasted to obtain a product.

In an optimized solution for the preparation method of the above natural gas hydrodesulfurization catalyst, the drying temperature is 50-500°C, preferably 50-300°C, and the roasting temperature is 100-850°C, preferably 200-300°C.

In the present invention, the active components cobalt and molybdenum are generally soluble salts. For example, cobalt nitrate and molybdenum nitrate are combined with the carrier by an impregnation method, which can be one impregnation or multiple impregnations; the addition of cocatalyst components can either It can be co-impregnated into the composite carrier with the active component in the form of a soluble salt, or it can be impregnated into the carrier separately from the active component.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses the metal-organic framework material MIL-101 (Cr) with high specific surface area and pore volume as the carrier, which not only provides more dispersed sites for the loaded catalyst active components and increases the number of catalyst active centers, but also the metal-organic framework material The metal central ion in the framework material structure has a coordinated unsaturated site, which can accept a pair of electrons to act as a Lewis acid, thereby promoting the adsorption and removal of alkaline thiophene and other macromolecule sulfides through these acidic sites, enhancing the organic The contact probability between sulfur molecules and the active components of the catalyst; at the same time, select cobalt and molybdenum as the mixed active components, supplemented by any two of B, F, P, Si, Mn, Ca, and Zn as additives, and limit the cobalt The molar ratio of molybdenum and additives is maintained in a specific range, so that the prepared catalyst can maintain a high conversion rate of organic sulfur in natural gas even at high space speeds, thus greatly improving the natural gas processing rate per unit time. The processing capacity of the hydrogen desulfurization process can not only effectively improve the quality of natural gas and strengthen environmental protection, but also help enterprises reduce production costs and improve production efficiency.

Description of the drawings

Figure 1 is a schematic structural diagram of the metal organic framework material MIL-101 (Cr) carrier prepared in Example 1;

Figure 2 is the micromorphology of the metal-organic framework material MIL-101 (Cr) carrier prepared in Example 1 under a scanning electron microscope;

Figure 3 is the nitrogen isothermal adsorption-desorption curve of the metal-organic framework material MIL-101 (Cr) carrier prepared in Example 1;

Figure 4 is the XRD characterization spectrum of the MIL-101 (Cr) activated sample prepared in Example 1 after adsorption of three sulfides;

Figure 5 is a comparison table of desulfurization rate data of each catalyst in the comparative experiment (when running for 120 hours);

Figure 6 is a table showing the changes in the desulfurization rate of each catalyst in the long-term experiment in the comparative experiment.

Detailed ways

The technical solutions of the present invention will be further described in detail below with reference to specific examples. The parts not explained in the following examples of the present invention should be understood as technologies that are known or should be known to those skilled in the art, such as the selection of cobalt and molybdenum. Soluble salts, ways to introduce additives such as B, F, P, Si, Mn, Ca, Zn, etc., and methods for preparing catalysts by impregnation, etc.

Example 1

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal-organic framework material MIL-101 (Cr), and its mass content accounts for 30% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 65% of the total catalyst. The cocatalyst component c is a mixture of Mn and Zn, and its mass content accounts for 5% of the total catalyst. The element molar ratio of the active component cobalt, active component molybdenum and cocatalyst component c is n _Co : n _Mo : n _c =3.5:10:3.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

① Mix chromium nitrate nonahydrate, terephthalic acid and deionized water at a molar ratio of 1:1:4.64 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 100°C for 24 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 80°C and the drying time is 50h; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 1500m ² /g and a pore volume of 1.39mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh manganese nitrate and zinc nitrate respectively as the cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step 4 evenly, then ultrasonic impregnate it for 2 hours, dry it at 50°C for 24 hours, and roast it at 850°C for 24 hours to obtain a semi-finished product. Catalyst powder;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, dry at 50°C for 24 hours, and roast at 100°C for 24 hours to obtain a product named CAT1.

Figure 1 is a schematic structural diagram of the metal organic framework material MIL-101 (Cr) carrier prepared in Example 1. MIL-101(Cr) is constructed from terephthalic acid ligands and trimer chromium [Cr ₃ O(CO ₂ ) ₆ ] octahedral clusters, containing two types of quasi-spherical cages with diameters of and/>

Figure 2 is the microscopic morphology of the metal organic framework material MIL-101 (Cr) carrier under a scanning electron microscope. It can be seen from the figure that the synthesized MIL-101 (Cr) crystals have uniform particle size and good dispersion. The particle size of the particles is about 100nm.

Figure 3 is the isothermal adsorption-desorption curve of nitrogen for the metal-organic framework material MIL-101 (Cr) carrier. As can be seen from Figure 3, the adsorption amount of the sample increases sharply in the area with lower relative pressure, indicating that there are a large number of micropores in the material. As the relative pressure increases, the adsorption amount of the material increases slowly, but there is no hysteresis loop. At a certain relative pressure, the adsorption amount of the material almost remains unchanged, indicating that the pore size distribution of the material is relatively concentrated and there are almost no mesopores. .

Figure 4 is the XRD characterization spectrum of the MIL-101 (Cr) activated sample prepared in Example 1 after adsorption of three sulfides. It can be seen from Figure 4 that the XRD spectrum after vulcanization is compared with that before vulcanization. The shape, position, and characteristics of the peaks have basically not changed, but the intensity of the peaks has weakened. Among them, the peak intensity of hydrogen sulfide has changed the most. It can be said that the adsorption of three sulfides only affects MIL-101 (Cr ) structure of the skeleton does not destroy its main structure. The structure of MIL-101(Cr) is more affected after adsorbing hydrogen sulfide than when adsorbing organic sulfur. On the one hand, this phenomenon may be due to the small amount participating in the reaction, which is not enough to cause damage to the entire structure. On the other hand, it also shows that the structure of MIL-101(Cr) itself is very stable.

Example 2

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a co-catalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 40% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 50% of the total catalyst. The cocatalyst component c is a mixture of B and Ca, and its mass content accounts for 10% of the total catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c =5:10:5.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.93 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, react at 200°C for 1 hour, and cool to room temperature after the reaction is completed;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 150°C and the drying time is 1 hour; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 1900 m ² /g and a pore volume of 3.26 mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh boric acid and calcium nitrate as the cocatalyst component c respectively, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then soak it with ultrasonic for 2 hours, then dry it at 500°C for 24 hours, and bake it at 100°C for 24 hours to obtain Semi-finished catalyst powder;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Soak in medium for 2 hours, dry at 500°C for 24 hours, and roast at 850°C for 24 hours to obtain a product named CAT2.

Example 3

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal-organic framework material MIL-101 (Cr), and its mass content accounts for 20% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 70% of the total amount of the catalyst. The cocatalyst component c is a mixture of F and P, and its mass content accounts for 10% of the total amount of the catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c =2:10:1.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.93 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 150°C for 12 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 90°C and the drying time is 25h; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 2200m ² /g and a pore volume of 2.24mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh hydrofluoric acid and phosphoric acid as cocatalyst component c respectively, and disperse them into deionized water to prepare a mixed solution of cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then ultrasonic impregnate it for 2 hours, dry it at 300°C for 24 hours, and bake it at 500°C. Semi-finished catalyst powder is obtained in 24 hours;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, then dry at 300°C for 24 hours, and roast at 500°C for 24 hours to obtain a product named CAT3.

Example 4

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 35% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 57% of the total catalyst. The cocatalyst component c is a mixture of B and Si, and its mass content accounts for 8% of the total catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c =3:10:2.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.93 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 180°C for 5 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 120°C and the drying time is 20 hours; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 2700 m ² /g and a pore volume of 1.90 mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh boric acid and silica sol respectively as cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then soak it with ultrasonic for 2 hours, dry it at 300°C for 24 hours, and bake it at 300°C. Semi-finished catalyst powder is obtained in 24 hours;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave The product was soaked for 2 hours, dried at 300°C for 24 hours, and roasted at 300°C for 24 hours to obtain a product named CAT4.

Example 5

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 25% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 70% of the total amount of the catalyst. The cocatalyst component c is a mixture of Ca and Zn, and its mass content accounts for 5% of the total amount of the catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c = 4:10:3.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.93 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 180°C for 9 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 110°C and the drying time is 10 hours; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 3500 m ² /g and a pore volume of 1.71 mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh calcium nitrate and zinc nitrate respectively as the cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the additive component mixed solution and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then ultrasonic impregnate it for 2 hours, dry it at 300°C for 24 hours, and bake it at 300°C for 24 hours. Obtain semi-finished catalyst powder;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, dry at 300°C for 24 hours, and roast at 300°C for 24 hours to obtain a product named CAT5.

Example 6

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 35% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 55% of the total amount of the catalyst. The cocatalyst component c is a mixture of F and Ca, and its mass content accounts for 10% of the total amount of the catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c =2.5:10:1.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.82 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 150°C for 5 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 120°C and the drying time is 36 hours; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 3900 m ² /g and a pore volume of 1.85 mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh hydrofluoric acid and calcium nitrate as the cocatalyst component c respectively, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then soak it with ultrasonic for 2 hours, dry it at 300°C for 24 hours, and bake it at 300°C. Semi-finished catalyst powder is obtained in 24 hours;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, dry at 300°C for 24 hours, and roast at 300°C for 24 hours to obtain a product named CAT6.

Example 7

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 25% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 65% of the total catalyst. The cocatalyst component c is a mixture of B and P, and its mass content accounts for 10% of the total catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c = 4.5:10:4.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

① Mix chromium nitrate nonahydrate, terephthalic acid and deionized water at a molar ratio of 1:1:4.76 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 180°C for 5 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 150°C and the drying time is 20h; the prepared metal organic framework material MIL-101 (Cr) has a specific surface area of approximately 3700m ² /g and a pore volume of 1.82mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh phosphoric acid and boric acid respectively as cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then soak it with ultrasonic for 2 hours, dry it at 300°C for 24 hours, and bake it at 300°C. Semi-finished catalyst powder is obtained in 24 hours;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, dry at 300°C for 24 hours, and roast at 300°C for 24 hours to obtain a product named CAT7.

Example 8

A natural gas hydrodesulfurization catalyst is composed of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal-organic framework material MIL-101 (Cr), and its mass content accounts for 29% of the total amount of the catalyst, so The active component b is a mixture of molybdenum and cobalt, and its mass content accounts for 70% of the total catalyst. The cocatalyst component c is a mixture of Si and Mn, and its mass content accounts for 1% of the total catalyst. The element molar ratio of the active component cobalt, the active component molybdenum and the cocatalyst component c is n _Co : n _Mo : n _c =3:10:4.5.

The preparation method of the catalyst is as follows:

1) Preparation of metal-organic framework material MIL-101(Cr);

①Mix chromium nitrate nonahydrate, terephthalic acid and deionized water evenly at a molar ratio of 1:1:4.93 to prepare a buffer solution for MIL-101 (Cr) metal organic framework material;

② Add hydrofluoric acid to the buffer solution, stir evenly, and react at 180°C for 7 hours. After the reaction is completed, cool to room temperature;

③Centrifuge and wash with N,N-dimethylformamide and absolute ethanol in sequence to remove unreacted terephthalic acid and N,N-dimethylformamide in the buffer solution;

④ Vacuum drying to remove absolute ethanol and crystal water to obtain the activated metal organic framework material MIL-101 (Cr);

The vacuum drying temperature is 120°C and the drying time is 20 hours; the specific surface area of the prepared metal-organic framework material MIL-101 (Cr) is approximately 3400m ² /g, and the pore volume is 1.83mL/g.

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh manganese nitrate and silica sol respectively as the cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step ④ evenly, then soak it with ultrasonic for 2 hours, dry it at 300°C for 24 hours, and bake it at 300°C. Semi-finished catalyst powder is obtained in 24 hours;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave The product was soaked for 2 hours, dried at 300°C for 24 hours, and roasted at 300°C for 24 hours to obtain a product named CAT8.

In order to verify the desulfurization effect of the catalyst of the present invention, the following comparative experiments were conducted:

Comparative example 1

It consists of carrier a, active component b and cocatalyst component c. The carrier a is a γ-A1 ₂ O ₃ carrier, whose mass content accounts for 30% of the total catalyst. The active component b is molybdenum and cobalt. The mixture, its mass content accounts for 65% of the total amount of the catalyst, the cocatalyst component c is a mixture of Mn and Zn, its mass content accounts for 5% of the total amount of the catalyst, and the active component cobalt, active component The element molar ratio of molybdenum and cocatalyst component c n _Co : n _Mo : n _c =3.5:10:3.

The preparation method of the catalyst is as follows:

1) The γ-A1 ₂ O ₃ carrier can be obtained by roasting pseudo-boehmite at 500°C for 4 hours;

2) According to the above proportion, the active component b and the cocatalyst component c are respectively impregnated onto the carrier a; the specific operation is:

Weigh manganese nitrate and zinc nitrate respectively as the cocatalyst component c, and disperse them into deionized water to prepare a mixed solution of the cocatalyst components;

Mix the mixed solution of additive components and the activated metal-organic framework material MIL-101 (Cr) prepared in step 4 evenly, then ultrasonic impregnate it for 2 hours, dry it at 50°C for 24 hours, and roast it at 850°C for 24 hours to obtain a semi-finished product. Catalyst powder;

Then take cobalt nitrate hexahydrate and molybdenum nitrate pentahydrate as active component b and evenly disperse them in deionized water to prepare an active component mixed solution. Then, mix the obtained semi-finished catalyst powder with the active component solution evenly, and then conduct ultrasonic wave Dip for 2 hours, dry at 50°C for 24 hours, and roast at 100°C for 24 hours to obtain a product named CAT1.

Comparative example 2

It consists of carrier a, active component b and cocatalyst component c. The carrier a is MIL-101 (Fe), whose mass content accounts for 30% of the total catalyst. The active component b is molybdenum and cobalt. The mixture has a mass content of 65% of the total amount of the catalyst, the cocatalyst component c is a mixture of Mn and Zn, and the mass content accounts for 5% of the total amount of the catalyst, and the active component cobalt, the active component molybdenum and the element molar ratio n _Co : n _Mo : n _c = 3.5:10:3 of the cocatalyst component c.

The preparation method is the same as Example 1.

Comparative example 3

It consists of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 30% of the total catalyst. The active component b is The mixture of molybdenum and cobalt has a mass content of 65% of the total catalyst, the cocatalyst component c is a mixture of K and Mg, and the mass content accounts for 5% of the total catalyst, and the active component cobalt, The element molar ratio of the active component molybdenum and the cocatalyst component c n _Co : n _Mo : n _c =3.5:10:3.

The preparation method is the same as Example 1.

Comparative example 4

It consists of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 30% of the total catalyst. The active component b is The mixture of molybdenum and cobalt has a mass content of 65% of the total catalyst, the cocatalyst component c is a mixture of Mn and Zn, and the mass content accounts for 5% of the total catalyst, and the active component cobalt, The element molar ratio of the active component molybdenum and the cocatalyst component c n _Co : n _Mo : n _c =7:10:6.

The preparation method is the same as Example 1.

Comparative example 5

It consists of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 30% of the total catalyst. The active component b is The mixture of molybdenum and cobalt has a mass content of 65% of the total catalyst, the cocatalyst component c is a mixture of Mn and Zn, and the mass content accounts for 5% of the total catalyst, and the active component cobalt, The element molar ratio of the active component molybdenum and the cocatalyst component c n _Co : n _Mo : n _c =1:10:0.5.

The preparation method is the same as Example 1.

Comparative example 6

It consists of a carrier a, an active component b and a cocatalyst component c. The carrier a is a metal organic framework material MIL-101 (Cr), and its mass content accounts for 30% of the total catalyst. The active component b is The mixture of molybdenum and cobalt has a mass content of 65% of the total catalyst, the cocatalyst component c is a mixture of Mn and Zn, and the mass content accounts for 5% of the total catalyst, and the active component cobalt, The element molar ratio of the active component molybdenum and the cocatalyst component c n _Co : n _Mo : n _c =1:10:7.

The preparation method is the same as Example 1.

Experiment content

The products CAT1-8 of the above-mentioned Examples 1-8 and the products of Comparative Examples 1-6 were used in the same natural gas hydrodesulfurization reaction. The reaction conditions were: the hydrogen content in the raw gas was 12%, the sulfur content was 350ppm; the reaction temperature The temperature is 350℃, the reaction pressure is 2.5MPa, and the raw gas air velocity is 20000h ^-1 .

The reaction performance and long-term test of the catalyst were tested respectively, and the results are shown in Figure 5 and Figure 6.

It can be seen from the table data in Figure 5 that when running for 120 hours, the desulfurization rate of the embodiment of the present invention is basically stable at more than 99%, while Comparative Example 1 using γ-A1 ₂ O ₃ as the carrier has an active component The cocatalyst is the same as that of the present invention, but the desulfurization rate is only about 68.17%; in Comparative Example 2, which uses MIL101 (Fe) as the carrier, the desulfurization rate is also maintained at 93.52%, while MIL-101 (Cr) is also used as the carrier. However, under different cocatalyst components and different proportions, the desulfurization efficiency is lower than that of the present invention. This shows that the present invention selects cocatalysts and active components of specific components to match MIL-101 (Cr), and in specific proportions, can achieve a good desulfurization effect.

As can be seen from the table data in Figure 6, under the same reaction temperature, pressure and space velocity (20000h ^-1 ), long-cycle natural gas hydrodesulfurization operation experiments were conducted on catalysts CAT1-8 and Comparative Examples 1-6, and it was found that After a long reaction, catalyst CAT1-8 still has high and stable catalytic activity, and the desulfurization efficiency is basically stable above 99.9%; while in Comparative Example 1, the desulfurization rate begins to gradually decrease after the hydrodesulfurization reaction proceeds for 192 hours, which is For ratios 2-6, the desulfurization rate begins to gradually decrease after the hydrodesulfurization reaction proceeds for 240 hours; the decrease in desulfurization rate indicates that the catalytic activity gradually decreases. The experimental results show that the present invention selects cocatalysts and active components of specific components to match MIL-101 (Cr), and at a specific ratio, has a longer catalyst life, high and stable catalytic activity, and greatly reduces the cost of natural gas processing. The usage cost of hydrodesulfurization catalyst.

Claims (10)

1. The natural gas hydrodesulfurization catalyst consists of a carrier a, an active component b and a cocatalyst component c, and is characterized in that: the carrier a is metal organic framework material MIL-101 (Cr), the mass content of which accounts for 20-40% of the total catalyst, the active component b is a mixture of molybdenum and cobalt, the mass content of which accounts for 50-70% of the total catalyst, the promoter component c is any two of B, F, P, si, mn, ca, zn,the mass content of the catalyst accounts for 1-10% of the total catalyst, and the element mole ratio n of the active component cobalt, the active component molybdenum and the promoter component c _Co ：n _Mo ：n _c ＝(2～5)：10：(1～5)。

2. The natural gas hydrodesulfurization catalyst according to claim 1, characterized in that: the promoter component c is a mixture of two of B, F, P, si, mn, ca, zn, preferably Zn and Mn, B and Ca, F and P, and B and Si.

3. The natural gas hydrodesulfurization catalyst according to claim 1, characterized in that: the mass content of the carrier a accounts for 25-35% of the total catalyst, the mass content of the active component b accounts for 55-65% of the total catalyst, and the mass content of the cocatalyst component c accounts for 5-8% of the total catalyst.

4. The natural gas hydrodesulfurization catalyst according to claim 1, characterized in that: the element mole ratio n of the active component cobalt, the active component molybdenum and the promoter component c _Co ：n _Mo ：n _c ＝3-4：10：3-4。

5. The natural gas hydrodesulfurization catalyst according to claim 1, characterized in that the preparation method of the metal organic framework material MILs-101 (Cr) is as follows:

(1) uniformly mixing chromium nitrate nonahydrate, terephthalic acid and deionized water in a molar ratio of 1:1 (4.64-4.93) to prepare a buffer solution of MIL-101 (Cr) metal organic framework material;

(2) adding hydrofluoric acid into the buffer solution, uniformly stirring, reacting for 1-24 h at 100-200 ℃, and cooling to room temperature after the reaction is finished;

(3) sequentially centrifugally washing with N, N-dimethylformamide and absolute ethyl alcohol to remove unreacted terephthalic acid and N, N-dimethylformamide in a buffer solution;

(4) and (3) drying in vacuum to remove absolute ethyl alcohol and crystal water, so as to obtain the activated metal-organic framework material MIL-101 (Cr).

6. The natural gas hydrodesulfurization catalyst according to claim 5, characterized in that: in the step (2), after hydrofluoric acid is added into the buffer solution, the reaction is carried out for 5 to 9 hours at the temperature of 150 to 180 ℃.

7. The natural gas hydrodesulfurization catalyst according to claim 5, characterized in that: in the step (4), the temperature of vacuum drying is 80-150 ℃, preferably 90-120 ℃, and the drying time is 1-50 h, preferably 5-20 h.

8. The natural gas hydrodesulfurization catalyst according to claim 1 or 5, characterized in that: the specific surface area of the metal organic framework material MIL-101 (Cr) is 100-6000 m ² Preferably 1000 to 4500m per gram ² The pore volume per gram is 0.01-5 mL/g, preferably 0.1-2 mL/g.

9. The method for preparing a natural gas hydrodesulfurization catalyst according to any one of claims 1 to 8, characterized in that: and respectively soaking the active component b and the cocatalyst component c on the carrier a, drying and roasting to obtain the product.

10. The method for preparing the natural gas hydrodesulfurization catalyst according to claim 9, characterized in that: the drying temperature is 50-500 ℃, preferably 50-300 ℃, and the roasting temperature is 100-850 ℃, preferably 200-300 ℃.