Catalyst for preparing isoparaffin from synthesis gas as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing isoparaffin from synthesis gas as well as a preparation method and application of the catalyst, and belongs to the technical field of molecular sieve catalysts, the preparation method comprises the following steps: S1, freezing and ball-milling a ZMQ-1 molecular sieve; s2, growing an iron-containing layered double-metal hydroxide on the surface of the ZMQ-1 molecular sieve; s3, freezing treatment: putting the ZMQ-1 molecular sieve with the iron-containing layered double hydroxides grown on the surface into a liquid nitrogen environment for low-temperature treatment for 3.5-5 minutes; s4, putting the obtained product into a tubular furnace, raising the temperature to 350-450 DEG C at the temperature raising rate of 5-8 DEG C / min, and keeping the temperature for 2-4 hours; s5, loading Pt and Mg by adopting a co-impregnation method; and S6, introducing H2 into the molecular sieve for reduction. According to the method, before the iron-containing layered double-metal hydroxide grows on the surface of the ZMQ-1 molecular sieve, the ZMQ-1 molecular sieve is subjected to freezing ball-milling treatment, and after the iron-containing layered double-metal hydroxide grows on the surface of the ZMQ-1 molecular sieve, low-temperature treatment is performed in a liquid nitrogen environment. And isobutane and C4 < + > isoparaffin can be selectively generated, and meanwhile, the conversion efficiency of CO is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular sieve catalysts, and in particular to a catalyst for preparing isoparaffins from synthesis gas, a preparation method thereof and an application thereof. Background Art

[0002] Synthesis gas to isoparaffins is the process of converting a mixture of carbon monoxide and hydrogen (synthesis gas) into isoparaffins. Synthesis gas is passed into a reactor containing a catalyst and reacted under appropriate conditions of temperature, pressure, and space velocity to convert the syngas into isoparaffins.

[0003] Molecular sieve-based catalysts, due to their unique pore structure and acidic sites, exhibit shape-selective effects on reacting molecules, favoring the production of isoparaffins of specific sizes and shapes. However, this poses a challenge in controlling product distribution, a problem typically addressed by modifying the molecular sieve to adjust its acidity, pore structure, and surface properties.

[0004] Patent application number 202410606237.8 discloses a novel silicate zeolite molecular sieve, ZMQ-1, and its uses. This molecular sieve exhibits high thermal and hydrothermal stability, abundant Br acid sites, and moderately high Br acid strength. However, its use as a catalyst for synthesizing isoparaffins from syngas is limited, and the technical challenge of modifying it to achieve selective regulation remains unresolved.

[0005] Based on this, the present invention designs a catalyst for preparing isoparaffins from synthesis gas, and its preparation method and application to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a catalyst for preparing isoparaffins from synthesis gas, and a preparation method and application thereof.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for preparing a catalyst for preparing isoparaffins from synthesis gas comprises the following steps:

[0009] S1. ZMQ-1 molecular sieve cryo-milling treatment: freeze the ZMQ-1 molecular sieve at -75 to -55°C for 20 to 30 minutes, then place it at -25 to 0°C for low-temperature ball milling for 5 to 10 minutes;

[0010] S2, growing iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve;

[0011] 0.2-0.4 parts of NiSO4·6H2O are mixed with 10-15 parts of water to obtain a NiSO4 solution, 1-1.2 parts of Fe2(SO4)3·9H2O are mixed with 20-25 parts of water to obtain a Fe2(SO4)3 solution, and then 5-20 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution are uniformly mixed to obtain a mixed solution, and the mixed solution is slowly added dropwise to 55-65 parts of ultrapure water, and NaOH solution and Na2SO4 solution are added at 65-70° C. under stirring until the pH value is adjusted to 9.5-9.8; after stirring for 1.5-2 hours, the solid particles are separated by centrifugation and washed until neutral, thereby obtaining an iron-containing layered double hydroxide precursor;

[0012] S3. Freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface into a liquid nitrogen environment for low-temperature treatment for 3.5 to 5 minutes;

[0013] S4. Place the resulting mixture in a tube furnace, raise the temperature to 350-450°C at a heating rate of 5-8°C / min, and maintain for 2-4 hours;

[0014] S5. Loading Pt and Mg by co-impregnation method: impregnating the molecular sieve with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution;

[0015] S6. Place the molecular sieve in a quartz tube and introduce H2 for reduction.

[0016] Furthermore, in step S2, the concentration of NaOH solution and Na2SO4 solution is 0.6-0.8 mol·L -1 .

[0017] Furthermore, in step S2, the stirring speed is controlled to be 185-255 r / min.

[0018] Furthermore, in step S5, the concentration of the H2PtCl6 solution is 0.01 to 0.03 mol / L.

[0019] Furthermore, in step S5, the concentration of the Mg(NO3)2 solution is 0.2-0.3 mol / L.

[0020] Furthermore, in step S5, the immersion temperature is 45-55° C., and the immersion time is 10-14 hours.

[0021] Furthermore, in step S6, the reduction is carried out at 450-500°C for 15-25 min at a heating rate of 8-10°C / min, and the H2 flow rate is 22-25 mL / min.

[0022] In order to better achieve the purpose of the present invention, the present invention also provides a catalyst for preparing isoparaffins from synthesis gas obtained according to the preparation method.

[0023] In order to better achieve the purpose of the present invention, the present invention also provides an application of the catalyst in preparing isoparaffins from synthesis gas.

[0024] Furthermore, the reaction conditions for preparing isoparaffins from synthesis gas are:

[0025] Reaction temperature: 305°C;

[0026] Hydrogen-carbon ratio: H2 / CO=1;

[0027] Airspeed: 500h -1 ;

[0028] Pressure: 1.0MPa.

[0029] Compared with the prior art, the present invention has the following beneficial effects: before growing the iron-containing layered double hydroxide on the surface of the ZMQ-1 molecular sieve, the ZMQ-1 molecular sieve is subjected to cryo-ball milling treatment; after growing the iron-containing layered double hydroxide on the surface of the ZMQ-1 molecular sieve, the ZMQ-1 molecular sieve is subjected to low-temperature treatment in a liquid nitrogen environment; the above-mentioned processes produce a synergistic effect, and the prepared catalyst has excellent performance in catalyzing Fischer-Tropsch synthesis, which is conducive to the selective generation of isobutane and C 4+ isoalkanes, while further improving the conversion efficiency of CO. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Example 1: In some embodiments, a method for preparing a catalyst for producing isoparaffins from synthesis gas comprises the following steps:

[0032] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -75°C for 30 min, then mill it at -25°C for 10 min using 1 mm grinding balls.

[0033] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.2 parts of NiSO4·6H2O were mixed with 15 parts of water to obtain NiSO4 solution, 1 part of Fe2(SO4)3·9H2O was mixed with 25 parts of water to obtain Fe2(SO4)3 solution, and then 5 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 65 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 65°C under stirring until the pH value was adjusted to 9.8; after stirring for 1.5 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.6 mol·L -1 ;Control the stirring speed to 185r / min;

[0034] S3, freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 3.5 minutes;

[0035] S4, placing the obtained product in a tube furnace, heating it to 450°C at a heating rate of 5°C / min, and maintaining it for 2h;

[0036] S5. Co-impregnation method was used to load Pt and Mg: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.01 mol / L, and the concentration of Mg(NO3)2 solution was 0.3 mol / L; the impregnation temperature was 45°C, and the impregnation time was 14 h;

[0037] S6. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 500°C for 15 min at a heating rate of 8°C / min, with an H2 flow rate of 25 mL / min.

[0038] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0039] Example 2: In some embodiments, a method for preparing a catalyst for producing isoparaffins from synthesis gas comprises the following steps:

[0040] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -55°C for 20 min, then ball-mill at 0°C for 5 min using 5 mm grinding balls;

[0041] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.4 parts of NiSO4·6H2O were mixed with 10 parts of water to obtain NiSO4 solution, 1.2 parts of Fe2(SO4)3·9H2O were mixed with 20 parts of water to obtain Fe2(SO4)3 solution, and then 20 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 55 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 70°C under stirring until the pH value was adjusted to 9.5; after stirring for 2 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.8 mol·L -1 ;Control the stirring speed to 255r / min;

[0042] S3, freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 5 minutes;

[0043] S4, placing the obtained product in a tube furnace, heating it to 350°C at a heating rate of 8°C / min, and maintaining it for 4 hours;

[0044] S5. Co-impregnation method was used to load Pt and Mg: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.03 mol / L, and the concentration of Mg(NO3)2 solution was 0.2 mol / L; the impregnation temperature was 55°C, and the impregnation time was 10 h;

[0045] S6. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 450°C for 25 min at a heating rate of 10°C / min, with an H2 flow rate of 22 mL / min.

[0046] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0047] Example 3: In some embodiments, a method for preparing a catalyst for producing isoparaffins from synthesis gas comprises the following steps:

[0048] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -70°C for 22 minutes, then mill it at -20°C for 6 minutes using 3 mm grinding balls.

[0049] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.3 parts of NiSO4·6H2O were mixed with 12 parts of water to obtain NiSO4 solution, 1.1 parts of Fe2(SO4)3·9H2O were mixed with 22 parts of water to obtain Fe2(SO4)3 solution, and then 7 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 58 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 68°C under stirring until the pH value was adjusted to 9.6; after stirring for 1.8 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 200r / min;

[0050] S3, freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 4 minutes;

[0051] S4, placing the obtained product in a tube furnace, heating it to 400°C at a heating rate of 6°C / min, and maintaining it for 3 hours;

[0052] S5. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.02 mol / L, and the concentration of Mg(NO3)2 solution was 0.25 mol / L; the impregnation temperature was 50°C, and the impregnation time was 12 h;

[0053] S6. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 495°C for 18 min at a heating rate of 9°C / min and an H2 flow rate of 23 mL / min.

[0054] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0055] Example 4: In some embodiments, a method for preparing a catalyst for preparing isoparaffins from synthesis gas comprises the following steps:

[0056] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -65°C for 26 minutes, then mill it at -15°C for 8 minutes using 2 mm grinding balls.

[0057] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.4 parts of NiSO4·6H2O were mixed with 13 parts of water to obtain NiSO4 solution, 1 part of Fe2(SO4)3·9H2O was mixed with 21 parts of water to obtain Fe2(SO4)3 solution, and then 16 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 61 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 66°C under stirring until the pH value was adjusted to 9.6; after stirring for 1.6 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 200r / min;

[0058] S3, freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 4 minutes;

[0059] S4, placing the obtained product in a tube furnace, heating it to 425°C at a heating rate of 6.5°C / min, and maintaining it for 2.6 hours;

[0060] S5. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.01 mol / L, and the concentration of Mg(NO3)2 solution was 0.2 mol / L; the impregnation temperature was 52°C, and the impregnation time was 11 h;

[0061] S6. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 500°C for 24 min at a heating rate of 8.5°C / min and an H2 flow rate of 23 mL / min.

[0062] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0063] Example 5: In some embodiments, a method for preparing a catalyst for producing isoparaffins from synthesis gas comprises the following steps:

[0064] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -60°C for 27 minutes, then mill it at -10°C for 9 minutes using 4 mm grinding balls.

[0065] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.3 parts of NiSO4·6H2O were mixed with 14 parts of water to obtain NiSO4 solution, 1.2 parts of Fe2(SO4)3·9H2O were mixed with 24 parts of water to obtain Fe2(SO4)3 solution, and then 18 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 62 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 69°C under stirring until the pH value was adjusted to 9.7; after stirring for 1.6 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 240r / min;

[0066] S3, freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 4.5 minutes;

[0067] S4, placing the obtained product in a tube furnace, heating it to 440°C at a heating rate of 7°C / min, and maintaining it for 3.5 hours;

[0068] S5. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.02 mol / L, and the concentration of Mg(NO3)2 solution was 0.2 mol / L; the impregnation temperature was 52°C, and the impregnation time was 13 h;

[0069] S6. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 480°C for 22 min at a heating rate of 9°C / min and an H2 flow rate of 24 mL / min.

[0070] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0071] Comparative Example 1: Preparation method of a catalyst for preparing isoparaffins from synthesis gas, the steps are as follows:

[0072] S1. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.3 parts of NiSO4·6H2O were mixed with 12 parts of water to obtain NiSO4 solution, 1.1 parts of Fe2(SO4)3·9H2O were mixed with 22 parts of water to obtain Fe2(SO4)3 solution, and then 7 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 58 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 68°C under stirring until the pH value was adjusted to 9.6; after stirring for 1.8 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 200r / min;

[0073] S2. Freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface in a liquid nitrogen environment for low-temperature treatment for 4 minutes;

[0074] S3, placing the obtained product in a tube furnace, heating it to 400°C at a heating rate of 6°C / min, and maintaining it for 3 hours;

[0075] S4. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.02 mol / L, and the concentration of Mg(NO3)2 solution was 0.25 mol / L; the impregnation temperature was 50°C, and the impregnation time was 12 h;

[0076] S5. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 495°C for 18 min at a heating rate of 9°C / min and an H2 flow rate of 23 mL / min.

[0077] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0078] Comparative Example 2: Preparation method of a catalyst for preparing isoparaffins from synthesis gas, the steps are as follows:

[0079] S1. ZMQ-1 molecular sieve cryo-milling: freeze the ZMQ-1 molecular sieve at -70°C for 22 minutes, then mill it at -20°C for 6 minutes using 3 mm grinding balls.

[0080] S2. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.3 parts of NiSO4·6H2O were mixed with 12 parts of water to obtain NiSO4 solution, 1.1 parts of Fe2(SO4)3·9H2O were mixed with 22 parts of water to obtain Fe2(SO4)3 solution, and then 7 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 58 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 68°C under stirring until the pH value was adjusted to 9.6; after stirring for 1.8 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 200r / min;

[0081] S3, placing the obtained product in a tube furnace, heating it to 400°C at a heating rate of 6°C / min, and maintaining it for 3 hours;

[0082] S4. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.02 mol / L, and the concentration of Mg(NO3)2 solution was 0.25 mol / L; the impregnation temperature was 50°C, and the impregnation time was 12 h;

[0083] S5. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 495°C for 18 min at a heating rate of 9°C / min and an H2 flow rate of 23 mL / min.

[0084] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0085] Comparative Example 3: Preparation method of a catalyst for preparing isoparaffins from synthesis gas, the steps are as follows:

[0086] S1. Growth of iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve: 0.3 parts of NiSO4·6H2O were mixed with 12 parts of water to obtain NiSO4 solution, 1.1 parts of Fe2(SO4)3·9H2O were mixed with 22 parts of water to obtain Fe2(SO4)3 solution, and then 7 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution were uniformly mixed to obtain a mixed solution, and the mixed solution was slowly added dropwise to 58 parts of ultrapure water, and NaOH solution and Na2SO4 solution were added at 68°C under stirring until the pH value was adjusted to 9.6; after stirring for 1.8 hours, the solid particles were separated by centrifugation and washed to neutrality to obtain an iron-containing layered double hydroxide precursor; wherein the concentrations of NaOH solution and Na2SO4 solution were 0.7 mol·L -1 ;Control the stirring speed to 200r / min;

[0087] S2. Place the resulting mixture in a tube furnace, raise the temperature to 400°C at a heating rate of 6°C / min, and maintain for 3 h;

[0088] S3. Pt and Mg were loaded by co-impregnation method: the molecular sieve was impregnated with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; the concentration of H2PtCl6 solution was 0.02 mol / L, and the concentration of Mg(NO3)2 solution was 0.25 mol / L; the impregnation temperature was 50°C, and the impregnation time was 12 h;

[0089] S4. Place the molecular sieve in a quartz tube, introduce H2, and reduce at 495°C for 18 min at a heating rate of 9°C / min and an H2 flow rate of 23 mL / min.

[0090] The reaction conditions for producing isoparaffins from syngas are: reaction temperature: 305°C; hydrogen-carbon ratio: H2 / CO = 1; space velocity: 500h -1 ; Pressure: 1.0MPa.

[0091] Experimental Example: The catalyst was filled into a fixed bed reactor, and the performance of the catalysts prepared in Examples 1-3 and Comparative Examples 1-2 in catalyzing Fischer-Tropsch synthesis was tested.

[0092] Table 1 Performance of catalysts for Fischer-Tropsch synthesis

[0093] project CO conversion mol% Isobutane selectivity% <![CDATA[C 4+ Isoparaffin selectivity%]]> Example 1 87.2 60.1 90.5 Example 2 90.1 62.7 91.6 Example 3 88.6 65.9 92.3 Comparative Example 1 60.3 31.6 60.1 Comparative Example 2 56.9 33.5 51.8 Comparative Example 3 41.5 14.6 31.7

[0094] The present invention performs cryo-ball milling on the ZMQ-1 molecular sieve before growing the iron-containing layered double hydroxide on the surface of the ZMQ-1 molecular sieve, and then performs low-temperature treatment in a liquid nitrogen environment after growing the iron-containing layered double hydroxide on the surface of the ZMQ-1 molecular sieve. The above processes produce a synergistic effect, and the prepared catalyst has excellent performance in catalyzing Fischer-Tropsch synthesis, which is conducive to the selective generation of isobutane and C 4+ isoalkanes, while further improving the conversion efficiency of CO.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a catalyst for preparing isoparaffins from synthesis gas, characterized in that: Here are the steps: S1. ZMQ-1 molecular sieve cryo-milling treatment: freeze the ZMQ-1 molecular sieve at -75 to -55°C for 20 to 30 minutes, then place it at -25 to 0°C for low-temperature ball milling for 5 to 10 minutes; S2, growing iron-containing layered double hydroxide on the surface of ZMQ-1 molecular sieve; 0.2-0.4 parts of NiSO4·6H2O are mixed with 10-15 parts of water to obtain a NiSO4 solution, 1-1.2 parts of Fe2(SO4)3·9H2O are mixed with 20-25 parts of water to obtain a Fe2(SO4)3 solution, and then 5-20 parts of ZMQ-1 molecular sieve, NiSO4 solution and Fe2(SO4)3 solution are uniformly mixed to obtain a mixed solution, and the mixed solution is slowly added dropwise to 55-65 parts of ultrapure water, and NaOH solution and Na2SO4 solution are added at 65-70° C. under stirring until the pH value is adjusted to 9.5-9.8; after stirring for 1.5-2 hours, the solid particles are separated by centrifugation and washed until neutral, thereby obtaining an iron-containing layered double hydroxide precursor; S3. Freezing treatment: placing the ZMQ-1 molecular sieve with iron-containing layered double hydroxides grown on its surface into a liquid nitrogen environment for low-temperature treatment for 3.5 to 5 minutes; S4. Place the resulting mixture in a tube furnace, raise the temperature to 350-450°C at a heating rate of 5-8°C / min, and maintain for 2-4 hours; S5. Loading Pt and Mg by co-impregnation method: impregnating the molecular sieve with a mixed solution of H2PtCl6 solution and Mg(NO3)2 solution; S6. Place the molecular sieve in a quartz tube and introduce H2 for reduction.

2. The method for preparing a catalyst for preparing isoparaffins from synthesis gas according to claim 1, wherein: In step S2, the concentration of NaOH solution and Na2SO4 solution is 0.6~0.8mol·L -1 .

3. The method for preparing the catalyst for preparing isoparaffins from synthesis gas according to claim 2, characterized in that: In step S2, the stirring speed is controlled to be 185-255 r / min.

4. The method for preparing the catalyst for preparing isoparaffins from synthesis gas according to claim 3, characterized in that: In step S5, the concentration of the H2PtCl6 solution is 0.01-0.03 mol / L, and the concentration of the Mg(NO3)2 solution is 0.2-0.3 mol / L.

5. The method for preparing the catalyst for preparing isoparaffins from synthesis gas according to claim 4, characterized in that: In step S5, the immersion temperature is 45-55° C., and the immersion time is 10-14 hours.

6. The method for preparing the catalyst for preparing isoparaffins from synthesis gas according to claim 5, characterized in that: The performance of the catalyst for Fischer-Tropsch synthesis is: CO conversion ≥ 87.2 mol%, isobutane selectivity ≥ 60.1%, C 4+ Isoparaffin selectivity ≥90.5%.

7. The method for preparing the catalyst for preparing isoparaffins from synthesis gas according to claim 6, characterized in that: In step S6, reduction is carried out at 450-500° C. for 15-25 min at a heating rate of 8-10° C. / min and a H 2 flow rate of 22-25 mL / min.

8. A catalyst for preparing isoparaffins from synthesis gas obtained by the preparation method according to claim 7.

9. Use of the catalyst according to claim 8 in preparing isoparaffins from synthesis gas.

10. Use of the catalyst according to claim 8 in preparing isoparaffins from synthesis gas, characterized in that: The reaction conditions for producing isoparaffins from synthesis gas are: Reaction temperature: 305°C; Hydrogen-carbon ratio: H2 / CO=1; Airspeed: 500h -1 ; Pressure: 1.0MPa; Catalytic performance of Fischer-Tropsch synthesis: CO conversion ≥ 87.2 mol%, isobutane selectivity ≥ 60.1%, C 4+ Isoparaffin selectivity ≥90.5%.