A light hydrocarbon dehydrogenation and cracking synergistic catalyst and a preparation method thereof

Abstract

The application discloses a light hydrocarbon dehydrogenation and cracking synergic catalyst and a preparation method thereof. The catalyst contains the following components in percentage by weight: 30-70% of molecular sieve in dry basis; 5-10% of a first binder in dry basis; 0.2-6% of a metal compound in dry basis; 10-20% of a powder in dry basis; 5-10% of a second binder in dry basis; and 10-30% of clay in dry basis. The preparation method comprises the following steps: a. preparing a catalytic cracking catalyst; b. preparing a catalytic dehydrogenation catalyst; and c. spray granulation to prepare a microspherical catalyst product. The application has the beneficial effect of having a core-shell structure, which can maximize the dehydrogenation and cracking synergic catalytic effect, thereby maximizing the single-pass conversion rate, inhibiting hydrogen transfer, aromatization and other reactions, and achieving the purpose of improving the ethylene and propylene yield.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to a synergistic catalyst for the dehydrogenation and cracking of light hydrocarbons and its preparation method. Background Technology

[0002] Ethylene, propylene, and other low-carbon olefins are important petrochemical raw materials, and their output is a key indicator of a country's petrochemical development level. Low-carbon olefins have a wide variety of high-value downstream products, mainly including polyethylene, polypropylene, synthetic resins, synthetic fibers, and carbon materials.

[0003] Currently, most of the world's ethylene and propylene are produced through steam cracking, which consumes a large amount of energy per unit product. Compared with steam cracking, catalytic cracking technology can significantly reduce energy consumption, increase olefin yield, and offer flexible and adjustable product distribution. With the improvement of China's refining capacity and the expansion of ethylene production, the output of C4-C7 alkanes as a byproduct of refineries is also increasing significantly. However, C4-C7 alkanes have low added value and are mostly used as low-value fuels. Using dehydrogenation cracking technology to convert these resources into low-carbon olefins such as ethylene and propylene can both improve the utilization rate of light hydrocarbon chemicals and achieve the goal of producing more low-carbon olefins.

[0004] Existing catalysts still suffer from problems such as low yields of ethylene and propylene, low conversion rates of light hydrocarbon components, and high methane yields during the reaction process. These issues affect the stability and technical and economic efficiency of the unit, and limit the further promotion of light hydrocarbon dehydrogenation cracking technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a synergistic catalyst for the dehydrogenation and cracking of light hydrocarbons, which has a core-shell structure, thereby maximizing the synergistic catalytic effect of dehydrogenation and cracking, thereby maximizing the single-pass conversion rate, inhibiting reactions such as hydrogen transfer and aromatization, and achieving the goal of increasing the yield of ethylene and propylene.

[0006] To achieve the above objectives, the present invention adopts the following technical solution, including:

[0007] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons, wherein the catalyst is any one of the catalysts described above, characterized by comprising the following steps:

[0008] a. Weigh 300–700 parts by weight of molecular sieve and 50–100 parts by weight of the first binder, mix them evenly to form a powder, and then roll the powder into balls; then dry it at 100–200℃ for 2–6 hours; finally, calcine it at 550–650℃ for 2–6 hours to obtain a catalytic cracking catalyst. The obtained catalytic cracking catalyst is sieved, and catalysts with a particle size in the range of 5–50 μm are selected; the sieve rate is 10–20%.

[0009] b. Weigh 0.2–6 parts by weight of one or two of chromium nitrate, ferric nitrate, cobalt nitrate, nickel nitrate, and platinum chloride, and weigh 10–20 parts by weight of powder; add the weighed metal compound to 10–20 parts by weight of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed powder; then dry at 100–200°C for 2–6 hours; finally calcine at 550–650°C for 2–6 hours to obtain a catalytic dehydrogenation catalyst;

[0010] c. The catalytic dehydrogenation catalyst obtained in step b, along with 5-10 parts by weight of the second binder and 10-30 parts by weight of clay, are added to 20-30 parts by weight of deionized water and mixed evenly to form a slurry. 35-80 parts by weight of the catalytic cracking catalyst obtained by sieving are weighed. The weighed catalytic cracking catalyst is added to the slurry and stirred evenly. The pH is then adjusted to 2-6 with an acidic solution. Spray granulation is then performed, controlling the outlet temperature at 140-150℃ and the atomizer speed at 5000-10000 r / min. The solid content of the slurry is 10-30%. The slurry is then dried at 100-200℃ for 2-6 hours. Finally, it is calcined at 550-650℃ for 2-6 hours to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with microspheres of 40-200 μm.

[0011] Wherein, the molecular sieve is one or two of ZSM-5, Y, β, and SAPO-34 zeolite; the first binder is any one of boehmite, alumina sol, and silica sol; the metal compound is one or two of chromium nitrate, ferric nitrate, cobalt nitrate, nickel nitrate, and platinum chloride; the powder is one or two of alumina, silicon dioxide, and titanium dioxide; the second binder is any one of silica sol and sodium silicate; and the clay is one or two of kaolin, bentonite, and attapulgite.

[0012] Preferably, the acidic solution is one or two of formic acid solution, acetic acid solution, nitric acid solution, and hydrochloric acid solution, and its hydrogen ion concentration is 0.1 to 10 mol / L.

[0013] Preferably, in step A, the selected particle size is in the range of 10 to 30 μm.

[0014] Preferably, in step C, the outlet temperature is controlled at 145°C, the atomizer speed is 8000 r / min, and the solid content of the slurry is 15%.

[0015] Preferably, in step C, the outer diameter of the microspheres as a co-catalyst for light hydrocarbon dehydrogenation cracking is 80–150 μm.

[0016] The beneficial effects of this invention are: it has a core-shell structure, which maximizes the synergistic catalytic effect of dehydrogenation and cracking, thereby maximizing the single-pass conversion rate, inhibiting hydrogen transfer, aromatization and other reactions, and achieving the goal of increasing the yield of ethylene and propylene. Detailed Implementation

[0017] The invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0018] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0019] Example 1

[0020] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0021] a. Weigh a total of 500g of ZSM-5 molecular sieve and SAPO-34, and 75g of aluminum sol, mix them evenly to form a powder, and roll the powder into balls; then dry it at 150℃ for 4h; finally calcin it at 600℃ for 4h to obtain a catalytic cracking catalyst; sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size of 10-30um; the sieve rate is 15%.

[0022] b. Weigh out a total of 3g of cobalt nitrate and nickel nitrate, and 15g of alumina; add the weighed cobalt nitrate and nickel nitrate to 15g of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed alumina; dry at 150℃ for 4h; finally calcine at 600℃ for 4h to obtain the catalytic dehydrogenation catalyst.

[0023] c. Add the catalytic dehydrogenation catalyst obtained in step b, 7g of silica sol, and 15g of kaolin to 25g of deionized water and mix evenly to form a slurry; weigh 65g of the sieved catalytic cracking catalyst; add the weighed catalytic cracking catalyst to the slurry and stir evenly, then adjust the pH to 4 with formic acid solution (hydrogen ion concentration of 5mol / L); then perform spray granulation, controlling the outlet temperature at 145℃ and the atomizer speed at 8000r / min, the solid content of the slurry is 15%; then dry at 150℃ for 4h; finally calcine at 600℃ for 4h to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with 80-150um microspheres.

[0024] Example 2

[0025] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0026] a. Weigh 300g of Y molecular sieve and 100g of pseudoboehmite and mix them evenly to form a powder. Roll the powder into balls. Dry it at 100℃ for 6h. Finally, calcine it at 550℃ for 6h to obtain a catalytic cracking catalyst. Sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size in the range of 5-50um. The sieving rate is 20%.

[0027] b. Weigh 0.2g of chromium nitrate and 20g of silicon oxide; add the weighed chromium nitrate to 10 parts of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed silicon oxide; dry at 200℃ for 2h; finally calcine at 650℃ for 2h to obtain the catalytic dehydrogenation catalyst.

[0028] c. Add the catalytic dehydrogenation catalyst obtained in step b, 5g of sodium silicate, and 30g of attapulgite to 20g of deionized water and mix thoroughly to form a slurry. Weigh 80g of the sieved catalytic cracking catalyst. Add the weighed catalytic cracking catalyst to the slurry and stir thoroughly. Then adjust the pH to 6 with acetic acid solution (hydrogen ion concentration of 0.1mol / L). Spray granulation is then performed, controlling the outlet temperature at 140℃ and the atomizer speed at 10000r / min. The solid content of the slurry is 10%. Dry at 100℃ for 6h. Finally, calcine at 650℃ for 2h to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with microspheres of 40-200um.

[0029] Example 3

[0030] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0031] a. Weigh 700g of β molecular sieve and 50g of silica sol, mix them evenly to form a powder, and roll the powder into balls; then dry it at 200℃ for 2h; finally calcine it at 650℃ for 2h to obtain a catalytic cracking catalyst; sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size in the range of 8-40um; the sieve rate is 10%.

[0032] b. Weigh 6g of ferric nitrate and 10g of titanium oxide; add the weighed ferric nitrate to 20 parts of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed titanium oxide; dry at 100℃ for 6h; finally calcine at 550℃ for 6h to obtain the catalytic dehydrogenation catalyst.

[0033] c. Add the catalytic dehydrogenation catalyst obtained in step b, 10g of sodium silicate, and 10g of bentonite to 30g of deionized water and mix evenly to form a slurry; weigh 35g of the sieved catalytic cracking catalyst; add the weighed catalytic cracking catalyst to the slurry and stir evenly, then adjust the pH to 2 with nitric acid solution (hydrogen ion concentration of 10mol / L); then perform spray granulation, controlling the outlet temperature at 150℃ and the atomizer speed at 5000r / min, the solid content of the slurry is 30%; then dry at 200℃ for 2h; finally calcinate at 550℃ for 6h to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with microspheres of 50-190um.

[0034] Example 4

[0035] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0036] a. Weigh a total of 400g of Y molecular sieve and β molecular sieve, and 60g of aluminum sol, mix them evenly to form a powder, and roll the powder into balls; then dry it at 120℃ for 3h; finally calcine it at 590℃ for 5h to obtain a catalytic cracking catalyst; sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size in the range of 10-40um; the sieve rate is 16%.

[0037] b. Weigh out a total of 5g of nickel nitrate and platinum chloride, and a total of 16g ​​of silicon oxide and titanium oxide; add the weighed nickel nitrate and platinum chloride to 18 parts of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed silicon oxide and titanium oxide; dry at 120℃ for 5.5h; finally calcine at 560℃ for 2.5h to obtain the catalytic dehydrogenation catalyst;

[0038] c. The catalytic dehydrogenation catalyst obtained in step b, along with 6g of silica sol, a total of 28g of bentonite and attapulgite, are added to 28g of deionized water and mixed evenly to form a slurry. 50g of the sieved catalytic cracking catalyst is weighed out. The weighed catalytic cracking catalyst is added to the slurry and stirred evenly. The pH is then adjusted to 2.1 using a mixed solution of nitric acid and hydrochloric acid (with a hydrogen ion concentration of 2mol / L). Spray granulation is then performed, controlling the outlet temperature at 142℃ and the atomizer speed at 5500r / min. The solid content of the slurry is 28%. The slurry is then dried at 185℃ for 5.6h and finally calcined at 620℃ for 3.1h to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with microspheres of 60-190μm.

[0039] Comparative Example 1

[0040] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0041] a. Weigh a total of 200g of ZSM-5 molecular sieve and SAPO-34, and 125g of aluminum sol, mix them evenly to form a powder, and roll the powder into balls; then dry it at 80℃ for 1.5h; finally calcin it at 700℃ for 1h to obtain a catalytic cracking catalyst; sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size of 55-100um; the sieve rate is 45%.

[0042] b. Weigh out a total of 10g of cobalt nitrate and nickel nitrate, and 5g of alumina; add the weighed cobalt nitrate and nickel nitrate to 30g of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed alumina; dry at 250℃ for 1h; finally calcine at 400℃ for 12h to obtain the catalytic dehydrogenation catalyst.

[0043] c. Add the catalytic dehydrogenation catalyst obtained in step b, 15g of silica sol, and 5g of kaolin to 40g of deionized water and mix evenly to form a slurry; weigh 100g of the sieved catalytic cracking catalyst; add the weighed catalytic cracking catalyst to the slurry and stir evenly, then adjust the pH to 6.5 with formic acid solution (hydrogen ion concentration of 5mol / L); then perform spray granulation, controlling the outlet temperature at 160℃ and the atomizer speed at 12000r / min, with the solid content of the slurry being 40%; then dry at 120℃ for 8h; finally calcine at 700℃ for 1.5h to obtain the finished catalyst.

[0044] Comparative Example 2

[0045] A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons includes the following steps:

[0046] a. Weigh a total of 800g of ZSM-5 molecular sieve and 35g of aluminum sol, mix them evenly to form a powder, and roll the powder into balls; then dry it at 300℃ for 7h; finally calcin it at 400℃ for 8h to obtain a catalytic cracking catalyst; sieve the obtained catalytic cracking catalyst and select the catalytic cracking catalyst with a particle size of 1-4μm; the sieve rate is 5%.

[0047] b. Weigh out a total of 0.1g of cobalt nitrate and 25g of alumina; add the weighed cobalt nitrate to 5g of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed alumina; dry at 80℃ for 12h; finally calcine at 800℃ for 1h to obtain the catalytic dehydrogenation catalyst.

[0048] c. Add the catalytic dehydrogenation catalyst obtained in step b, 4g of silica sol, and 35g of kaolin to 8g of deionized water and mix evenly to form a slurry; weigh 80g of the sieved catalytic cracking catalyst; add the weighed catalytic cracking catalyst to the slurry and stir evenly, then adjust the pH to 1.5 with formic acid solution (hydrogen ion concentration of 5mol / L); then perform spray granulation, controlling the outlet temperature at 130℃ and the atomizer speed at 4000r / min, with the solid content of the slurry being 8%; then dry at 210℃ for 1h; finally calcine at 500℃ for 12h to obtain the finished catalyst.

[0049] Data Analysis

[0050] The composition of the light hydrocarbons to be processed is shown in Table 1.

[0051] Table 1

[0052] Components n-Alkanes / wt.% Isoalkanes / wt.% Cycloalkanes / wt.% Aromatics / wt.% C4 7.5 7.6 0 0 C5 12.2 50.3 1.1 0 C6 1.2 15.1 1.9 0.1 C7 0 2.6 0.4 0 total 20.9 75.6 3.4 0.1

[0053] Using the aforementioned light hydrocarbons as raw materials, the reaction was carried out at a temperature of 650℃, a pressure of 0.1 MPa, and a mass hourly space velocity of 1.0 h⁻¹. -1 The reaction performance of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 was evaluated using fluidized bed reactors, and the results are shown in Table 2.

[0054] Table 2

[0055] project Conversion rate / % Methane yield / wt% Ethylene yield / wt% propylene yield / wt% Diene yield / wt% Example 1 59.3 0.2 25.5 28.3 53.8 Example 2 58.6 0.3 22.5 25.2 47.7 Example 3 58.2 0.5 22.2 24.6 46.8 Example 4 59.5 0.9 22.4 22.5 44.9 Comparative Example 1 49.1 2.1 15.1 20.1 35.2 Comparative Example 2 48.2 2.2 15.6 18.7 34.3

[0056] As shown in Table 2, the light hydrocarbon dehydrogenation and cracking synergistic catalyst prepared according to this invention exhibits relatively high conversion rates and yields of ethylene and propylene, but relatively low methane yields. This will maximize the synergistic catalytic effect of dehydrogenation and cracking, thereby maximizing the single-pass conversion rate and suppressing reactions such as hydrogen transfer and aromatization, ultimately achieving the goal of increasing the yields of ethylene and propylene.

[0057] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a co-catalyst for the dehydrogenation and cracking of light hydrocarbons, characterized in that, Includes the following steps: a. Weigh 300–700 parts by weight of molecular sieve and 50–100 parts by weight of the first binder, mix them evenly to form a powder, and then roll the powder into balls; then dry it at 100–200℃ for 2–6 hours; finally, calcine it at 550–650℃ for 2–6 hours to obtain a catalytic cracking catalyst. The obtained catalytic cracking catalyst is sieved, and catalysts with a particle size in the range of 5–50 μm are selected; the sieve rate is 10–20%. b. Weigh 0.2–6 parts by mass of a metal compound and 10–20 parts by mass of a powder; add the weighed metal compound to 10–20 parts by mass of deionized water and stir evenly to prepare an impregnation solution; then spray the impregnation solution onto the weighed powder; then dry at 100–200°C for 2–6 hours; finally calcine at 550–650°C for 2–6 hours to obtain a catalytic dehydrogenation catalyst; c. The catalytic dehydrogenation catalyst obtained in step b, along with 5-10 parts by weight of the second binder and 10-30 parts by weight of clay, are added to 20-30 parts by weight of deionized water and mixed evenly to form a slurry. 35-80 parts by weight of the catalytic cracking catalyst obtained by sieving are weighed. The weighed catalytic cracking catalyst is added to the slurry and stirred evenly. The pH is then adjusted to 2-6 with an acidic solution. Spray granulation is then performed, controlling the outlet temperature at 140-150℃ and the atomizer speed at 5000-10000 r / min. The solid content of the slurry is 10-30%. The slurry is then dried at 100-200℃ for 2-6 hours. Finally, it is calcined at 550-650℃ for 2-6 hours to obtain a light hydrocarbon dehydrogenation cracking synergistic catalyst with microspheres of 40-200 μm. Wherein, the molecular sieve is one or two of ZSM-5, Y, β, and SAPO-34 zeolite; the first binder is any one of boehmite, alumina sol, and silica sol; the metal compound is one or two of chromium nitrate, ferric nitrate, cobalt nitrate, nickel nitrate, and platinum chloride; the powder is one or two of alumina, silicon dioxide, and titanium dioxide; the second binder is any one of silica sol and sodium silicate; and the clay is one or two of kaolin, bentonite, and attapulgite.

2. The method for preparing the light hydrocarbon dehydrogenation cracking co-catalyst according to claim 1, characterized in that: The acidic solution is one or two of formic acid solution, acetic acid solution, nitric acid solution, and hydrochloric acid solution, and its hydrogen ion concentration is 0.1 to 10 mol / L.

3. The method for preparing the light hydrocarbon dehydrogenation cracking co-catalyst according to claim 1, characterized in that: In step A, the selected particle size is in the range of 10 to 30 μm.

4. The method for preparing the light hydrocarbon dehydrogenation cracking synergistic catalyst according to claim 1, characterized in that: In step C, the outlet temperature is controlled at 145°C, the atomizer speed is 8000 r / min, and the solid content of the slurry is 15%.

5. The method for preparing the light hydrocarbon dehydrogenation cracking co-catalyst according to claim 1, characterized in that: In step C, the outer diameter of the microspheres as a co-catalyst for light hydrocarbon dehydrogenation cracking is 80–150 μm.