Preparation method of catalyst for preparing methanol from synthesis gas

Abstract

The preparation method comprises the following steps: (1) adding a first aluminum source with the pH value of 4.5-6.0 into a gel forming tank, then adding a copper-aluminum mixed solution and a composite precipitator into the gel forming tank to carry out gel forming reaction, controlling the pH value to gradually increase to 9.0-12.5, adding a zinc source after increasing every time, and stirring until the pH value is gradually increased to 9.0-12.5; after the gelling reaction is finished, obtaining a gelling substance; (2) aging a part of the gelatinizing material obtained in the step (1), and mixing the aged material with the material which does not participate in aging to obtain a mixed material; and (3) aging the mixed material, adding a second aluminum source in the aging process, after the aging is finished, carrying out solid-liquid separation, drying a solid phase, tabletting and molding to obtain a molded substance, washing, drying and roasting to obtain the catalyst for preparing methanol from synthesis gas. According to the method disclosed by the invention, the dispersity of the active metal copper and the assistant zinc in the catalyst is further improved by increasing the proportion of large-aperture channels.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of methanol synthesis from synthesis gas, and particularly relates to a preparation method of a methanol synthesis catalyst from synthesis gas. BACKGROUND

[0002] The synthesis methanol catalyst mainly comprises CuO, ZnO and Al2O3, CuO is the main active component, and ZnO and Al2O3 are the additives. The pore structure and specific surface area of the catalyst have a great influence on the activity, methanol selectivity and stability of the methanol catalyst. The catalyst with large-pore channels and large specific surface area can promote the exposure of more Cu metal atoms on the specific surface of the catalyst, is beneficial to the dispersion of the active component copper of the catalyst and the formation of smaller particles, and less agglomeration, reduces sintering, reduces the particle size of Cu, and the smaller Cu particle size can increase the yield of the product. At the same time, the large-pore channels and large specific surface area can also promote the formation of Cu / Zn synergies of the catalyst, greatly improve the activity and selectivity of the catalyst.

[0003] CN107790137A discloses a preparation method of a synthesis methanol catalyst, which utilizes the impact of gas on the pores of the catalyst during calcination to change the pore volume and specific surface area of the catalyst. Although the active metal copper content in the catalyst prepared by the two methods is high, the channels are easy to collapse under the action of water vapor pressure and the impact of water molecules, which reduces the dispersion of copper and zinc in the surface phase of the catalyst, and the particle size of copper is also large.

[0004] CN116943664A discloses a preparation method of a synthesis methanol catalyst. A Zn and Cu-containing solution and a sodium metaaluminate solution are co-currently gelled, then n times of tertiary decreasing pH value aging is continuously carried out, 1 / n Al-containing solution is added at the end of the first level of pH value aging each time, and the material obtained after aging is subjected to solid-liquid separation, the solid phase is dried, tablet-pressed, desalted, washed, dried and calcined to obtain the synthesis methanol catalyst. The catalyst prepared by the method has large pore volume and pore size, but small specific surface area, and cannot further improve the dispersion of metal copper and the additive zinc. SUMMARY

[0005] In view of the deficiencies in the prior art, the application provides a preparation method of a synthesis methanol catalyst from synthesis gas. The method improves the dispersion of active metal copper and the additive zinc by increasing the proportion of large-pore channels, and the catalyst has good activity, selectivity and thermal stability when applied to the synthesis gas to methanol reaction.

[0006] The preparation method of the synthesis methanol catalyst from synthesis gas of the application comprises the following contents:

[0007] (1) Add a first aluminum source with a pH value of 4.5 to 6.0 to a gelling tank, and then add a copper-aluminum mixed solution and a composite precipitant to the gelling tank to carry out a gelling reaction. Control the pH value to increase gradually to 9.0 to 12.5. After each increase, add one part of zinc source. After the gelling reaction is completed, a gel is obtained. The number of pH value increases is 2 to 10 times, preferably 3 to 8 times.

[0008] (2) Take a portion of the gelling material obtained in step (1) and age it. Mix the aged material with the material that did not participate in aging to obtain a mixture.

[0009] (3) The mixture is aged, and a second aluminum source is added during the aging process. After aging, the solid and liquid phases are separated, and the solid phase is dried and pressed into tablets to obtain the molded product. The product is then washed, dried and calcined to obtain the syngas to methanol catalyst.

[0010] In the method of the present invention, the concentration of the first aluminum source in step (1) is 2 to 100 g / L by weight, preferably 6 to 95 g / L, based on Al2O3; the aluminum source is selected from one or more aqueous solutions of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate; based on Al2O3, the Al in the first aluminum source accounts for 10% to 40% of the Al in the catalyst, preferably 13% to 38%.

[0011] In the method of the present invention, the composite precipitant in step (1) is an ammonia solution and a sodium carbonate solution. The molar ratio of ammonia to sodium carbonate in the composite precipitant is 0.3:1 to 0.7:1, the concentration of ammonia is 5wt% to 12wt%, and the concentration of sodium carbonate solution is 8wt% to 20wt%.

[0012] In the method of the present invention, the pH adjustment in step (1) can be carried out using the above-mentioned composite precipitant.

[0013] In the method of this invention, in the copper-aluminum mixed solution described in step (1), the copper salt concentration is expressed as Cu 2+ The concentration is 0.2–4.5 mol / L, preferably 0.3–4.0 mol / L, and the weight concentration of the aluminum salt, calculated as Al2O3, is 2–100 g / L, preferably 6–95 g / L; wherein the copper salt is a copper-containing nitrate and / or acetate, and the aluminum salt is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum acetate.

[0014] In the method of this invention, the zinc source in step (1) is an aqueous solution containing zinc nitrate and / or acetate, with a concentration expressed as Zn. 2+ The concentration is calculated to be 0.1–3.5 mol / L, preferably 0.1–3.0 mol / L; the zinc source is used to divide the solution volume into equal parts according to the incrementing number of times.

[0015] In the method of the present invention, the gelation reaction temperature in step (1) is 40-90℃.

[0016] In the method of the present invention, during the gelation reaction process described in step (1), the pH value increment is preferably kept constant at 0.05 to 0.5 hours after each increment, and the increment of pH value can be the same or different each time.

[0017] In the method of the present invention, the volume ratio of the unaged gelling material in step (2) to the gelling material obtained in step (1) is 0.2:1 to 0.5:1, preferably 0.22:1 to 0.48:1.

[0018] In the method of the present invention, the aging conditions in step (2) are as follows: aging temperature is 90-98℃, aging pH value is 10.5-13.8, preferably 11.0-13.5, and aging time is 1.0-5.0 hours, preferably 1.2-4.0 hours.

[0019] In the method of the present invention, the weight concentration of the second aluminum source in step (3) is 2 to 90 g / L, preferably 6 to 85 g / L, based on Al2O3; the second aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate aqueous solution; based on Al2O3, the Al in the second aluminum source accounts for 18% to 40% of the Al in the catalyst, preferably 20% to 38%.

[0020] In the method of this invention, the aging conditions in step (3) are as follows: aging temperature is 40–80°C, preferably 45–78°C; aging pH value is 7.0–10.0, preferably 7.5–9.5; and aging time is 1.0–4.0 hours, preferably 1.5–3.0 hours. The second aluminum source is preferably added at the beginning of aging, and the addition time of the second aluminum source solution is 30%–70% of the aging time.

[0021] In the method of the present invention, the solid-liquid separation in step (3) generally adopts methods such as filtration and centrifugation.

[0022] In the method of the present invention, during the molding process described in step (3), conventional molding extrusion aids can be added as needed. The extrusion aids refer to substances that are beneficial to extrusion molding, such as one or more of carbon black, graphite powder, etc. The amount of extrusion aids accounts for 1wt% to 10wt% of the total dry basis of the material.

[0023] In the method of this invention, the washing, drying, and calcination in step (3) can be performed under conventional conditions in the art. The washing is done with deionized water until neutral. The drying conditions are: drying temperature of 50–150°C and drying time of 0.5–24.0 hours. The calcination conditions are: calcination temperature of 320–450°C and calcination time of 1–16 hours.

[0024] The present invention also provides a catalyst for syngas to methanol production, wherein the pore volume of pores larger than 15 nm accounts for more than 91% of the total pore volume, preferably 91% to 99%.

[0025] The syngas-to-methanol catalyst of the present invention has the following pore size distribution: pores smaller than 15 nm account for 1% to 9% of the total pore volume; pores between 15 and 20 nm account for 41% to 49% of the total pore volume; pores between 20 and 30 nm account for 3% to 11% of the total pore volume; pores between 30 and 35 nm account for 42% to 50% of the total pore volume; and pores larger than 35 nm account for 5% to 13% of the total pore volume. A preferred pore size distribution is as follows: pores smaller than 15 nm account for 1% to 8% of the total pore volume; pores between 15 and 20 nm account for 41% to 47% of the total pore volume; pores between 20 and 30 nm account for 3% to 9% of the total pore volume; pores between 30 and 35 nm account for 42% to 48% of the total pore volume; and pores larger than 35 nm account for 5% to 11% of the total pore volume.

[0026] The syngas-to-methanol catalyst of the present invention comprises, by weight of the catalyst, the following components: CuO 30% to 68%, preferably 32% to 65%; ZnO 17% to 55%, preferably 19% to 47%; and Al2O3 15% to 53%, preferably 17% to 48%.

[0027] The specific surface area of ​​the syngas-to-methanol catalyst of the present invention is 200-650 m². 2 / g, with a pore volume of 0.40~1.00mL / g.

[0028] The syngas-to-methanol catalyst of the present invention has a specific surface area of ​​56–160 m² of metallic copper after reduction. 2 / g, preferably 60-155m 2 / g; the average particle size of metallic copper is 5-8 nm. The dispersion of metallic copper is 38%-65%, preferably 40%-63%.

[0029] The catalyst of this invention is applied to the methanol synthesis reaction, and the general process conditions are: reaction temperature 210–320°C, preferably 230–290°C; pressure 2.0–10.0 MPa, preferably 2.0–8.0 MPa; volume hourly space velocity 2000–15000 h⁻¹. -1 Preferably 4000~12000h -1 .

[0030] Compared with the prior art, the method of the present invention has the following advantages:

[0031] 1. The method of this invention employs a composite precipitant with a specific molar ratio, effectively controlling the particle size of metal oxides in the precursor and reducing the particle size of copper in the catalyst. Simultaneously, a step-by-step pH increment is used for gelation, introducing Zn during this process, which is more conducive to the formation of Cu / Zn synergies, further improving the dispersion of metallic copper in the catalyst. Furthermore, the step-by-step pH increment effectively controls the formation of pores with a diameter less than 15 nm.

[0032] 2. In the method of the present invention, the slurry obtained by gelation is aged under different conditions, so that the precursor material initially forms a bimodal pore structure. After reduction, the large pores in the catalyst make the copper particles uniform and dispersed, increasing the specific surface area of ​​the copper. The larger pore size can also improve the diffusion efficiency of the catalytic process. Adding aluminum solution during the aging process in step (3) helps to further form a bimodal pore distribution, improve the supporting role of Al2O3 in the composite oxide, and ensure a good synergistic effect between Cu-ZnO.

[0033] 3. The copper-zinc catalyst of this invention has a large proportion of pore volume above 15nm, a bimodal pore size distribution, a large specific surface area, and a particle size distribution mainly concentrated in the range of 5nm to 8nm. The increase in large-diameter pores in the catalyst allows more metal active component atoms to be exposed on the surface of the catalyst pores, thereby increasing the number of reactive centers. Detailed Implementation

[0034] The following examples further illustrate the scheme and effects of the present invention. In the present invention, the specific surface area, pore volume, and pore distribution are determined by low-temperature liquid nitrogen adsorption method. The specific surface area (S) of the reduced catalyst metal Cu is... Cu ) and dispersion in the catalyst surface phase (D Cu The N2O chemical reaction adsorption method was used for determination.

[0035] In this invention, the average particle size and particle size distribution of metallic copper were obtained by measuring 50 to 120 metallic copper particles using a TEM transmission electron microscope (JSM-2100, Japan).

[0036] The content of active metals on the surface of the catalyst was determined by X-ray photoelectron spectroscopy (XPS), and the content of active metals in the bulk of the catalyst was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0037] Example 1

[0038] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare the first aluminum source, in which Al accounted for 25% of the total Al in the catalyst. 304 g of Cu(NO3)2·3H2O and 73.8 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 146 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into 5 equal portions by volume. AlCl3·6H2O was added to dissolving tank 4 containing deionized water to prepare the second aluminum source, in which Al accounted for 23% of the total Al in the catalyst. The first aluminum source solution was added to the reaction vessel at a reaction temperature of 62°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solutions was 0.48:1. The pH was controlled at 4.8. A Cu- and Al-containing solution and the composite precipitant were then fed into the reaction vessel. The pH was adjusted to 10.3 five times, with each adjustment being 1.1. After each adjustment, a zinc source was added. The pH of the adjusted reaction slurry was kept constant for 12 minutes, generating a gelling material containing copper, zinc, and aluminum. The resulting slurry was divided into two parts, and one part was used to form… The gel was aged at 92°C, with the pH value controlled at 12.7 and the aging time at 2.3 hours. The volume ratio of the unaged gel to the gel obtained in step (1) was 0.41. The unaged gel was cooled to 15°C. After aging, the unaged gel was mixed with the aged gel and aging continued. At the beginning of aging, a second aluminum source was added dropwise over 1.2 hours. The aging temperature was 57°C, the pH value controlled at 8.2, and the aging time was 2.2 hours. The aging was then stopped. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 90°C for 10 hours. A suitable amount of graphite and water were added and the mixture was rolled and pressed into tablets. The tablets were washed with deionized water at room temperature until neutral. The washed tablets were dried at 80°C for 12.0 hours. The dried tablets were calcined at 380°C for 3 hours to obtain catalyst A. The composition, pore distribution, and main properties are shown in Table 1.

[0039] Example 2

[0040] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare the first aluminum source, in which Al accounted for 20% of the Al in the catalyst. 310 g of Cu(NO3)2·3H2O and 57 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 161 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into 6 equal portions by volume. AlCl3·6H2O was added to dissolving tank 4 containing deionized water to prepare the second aluminum source, in which Al accounted for 35% of the Al in the catalyst. The first aluminum source was added to the reaction vessel at a reaction temperature of 72°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solution was 0.55:1. The pH was controlled at 4.7. A Cu- and Al-containing solution and the composite precipitant were then fed into the reaction vessel. The pH was adjusted to 11.3 six times, with each adjustment being 1.1. After each adjustment to the target value, a zinc source was added. The pH of the adjusted reaction slurry was kept constant for 12 minutes, generating a gelling material containing copper, zinc, and aluminum. The resulting slurry was divided into two parts, and one part was used to gel. The material was aged at a temperature of 95℃, with the aging pH controlled at 12.8 and an aging time of 2.6 hours. The volume ratio of the unaged material to the gelling material obtained in step (1) was 0.26. The unaged gelling material was cooled to 20℃. After aging, the unaged gelling material was mixed with the aged gelling material, and aging continued. At the beginning of aging, a second aluminum source was added dropwise over a period of 1.3 hours. The aging temperature was 68℃, the aging pH controlled at 8.5, and the aging time was 2.2 hours. The aging was then stopped. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 90℃ for 12 hours. An appropriate amount of graphite and water were added and the cake was pressed into tablets. The tablets were washed with deionized water at room temperature until neutral. The washed tablets were dried at 110℃ for 8.0 hours. The dried tablets were calcined at 400℃ for 4 hours to obtain catalyst B. The composition, pore distribution, and main properties are shown in Table 1.

[0041] Example 3

[0042] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare the first aluminum source, in which Al accounted for 26% of the total Al in the catalyst. 292 g of Cu(NO3)2·3H2O and 63.5 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 176 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into four equal volumes. AlCl3·6H2O was added to dissolving tank 4 containing deionized water to prepare the second aluminum source, in which Al accounted for 26% of the total Al in the catalyst. The first aluminum source was added to the reaction vessel at a reaction temperature of 60°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solution was 0.62:1. The pH was controlled at 5.6. A Cu- and Al-containing solution and the composite precipitant were then fed into the reaction vessel. The pH was adjusted to 10.8 four times, with each adjustment being 1.3. After each adjustment, a zinc source was added, and the pH of the adjusted reaction slurry was kept constant for 15 minutes to generate a gelling material containing copper, zinc, and aluminum. The resulting slurry was divided into two parts, and one part was used to gel. The material was aged at a temperature of 93℃, with the aging pH controlled at 12.0 and an aging time of 2.1 hours. The volume ratio of the unaged material to the gelling material obtained in step (1) was 0.38. The unaged gelling material was cooled to 25℃. After aging, the unaged gelling material was mixed with the aged gelling material, and aging continued. At the beginning of aging, a second aluminum source was added dropwise over a period of 1.0 hour. The aging temperature was 60℃, the aging pH controlled at 8.0, and the aging time was 2.0 hours. The aging was then stopped. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 125℃ for 7 hours. An appropriate amount of graphite and water were added and the cake was rolled and pressed into tablets. The tablets were washed with deionized water at room temperature until neutral. The washed tablets were dried at 100℃ for 9.0 hours. The dried tablets were calcined at 390℃ for 5 hours to obtain catalyst C. The composition, pore distribution, and main properties are shown in Table 1.

[0043] Example 4

[0044] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare the first aluminum source, in which Al accounted for 28% of the total Al in the catalyst. 328 g of Cu(NO3)2·3H2O and 43.7 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 154 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into 5 equal portions by volume. AlCl3·6H2O was added to dissolving tank 4 containing deionized water to prepare the second aluminum source, in which Al accounted for 32% of the total Al in the catalyst. The first aluminum source was added to the reaction vessel at a reaction temperature of 58°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solution was 0.36:1. The pH was controlled at 5.1. A Cu- and Al-containing solution and the composite precipitant were then fed into the reaction vessel. The pH was adjusted to 11.1 five times, with each adjustment being 1.2. After each adjustment, a zinc source was added. The pH of the adjusted reaction slurry was kept constant for 13 minutes, generating a gelling material containing copper, zinc, and aluminum. The resulting slurry was divided into two parts, and one part was used to gel. The material was aged at a temperature of 94℃, with the aging pH controlled at 12.7 and an aging time of 2.3 hours. The volume ratio of the unaged material to the gelling material obtained in step (1) was 0.30. The unaged gelling material was cooled to 15℃. After aging, the unaged gelling material was mixed with the aged gelling material, and aging continued. At the beginning of aging, a second aluminum source was added dropwise over a period of 1.4 hours. The aging temperature was 70℃, the aging pH controlled at 8.5, and the aging time was 2.7 hours. The aging was then stopped. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 80℃ for 10 hours. An appropriate amount of graphite and water were added and the cake was rolled, pressed into tablets, and washed with deionized water at room temperature until neutral. The washed tablets were dried at 90℃ for 10.0 hours. The dried tablets were calcined at 410℃ for 4 hours to obtain catalyst D. The composition, pore distribution, and main properties are shown in Table 1.

[0045] Comparative Example 1

[0046] The catalyst was prepared according to Example 1 disclosed in CN116943664A. Cu(NO3)2·3H2O and Zn(NO3)2·6H2O were dissolved in deionized water to prepare a solution containing Zn and Cu. 2+ The concentration is 3.8 mol / L, Zn 2+The concentration was 3.2 mol / L. AlCl3·6H2O was dissolved in deionized water to prepare an aluminum chloride solution. The Al in the aluminum chloride solution accounted for 26.2% of the total Al in the obtained methanol synthesis catalyst, calculated as Al2O3. The solution was then divided into four equal portions by volume. Deionized water was added to the reaction vessel. Sodium aluminate solution and mixed solution A were added to the reaction vessel in a parallel flow. The gelation temperature was 60℃, and the initial pH value was controlled at 13.1. The pH value was adjusted to 7.5 by decreasing it 7 times. Each pH value was decreased by 0.8. After each adjustment, the pH value of the reaction slurry was kept constant for 8 minutes. After the reaction was completed, a slurry containing copper, zinc, and aluminum was obtained. The obtained slurry was aged at 76℃. During aging, the pH value was initially controlled at 13.0 and the aging time was 0.3 hours. Then, an equal part of aluminum chloride solution was added, and the aging pH value was controlled at 9.5. After aging time was 0.2 hours, the pH value was then controlled at 7.6 and the aging time was 0.2 hours. The above operation process was repeated 4 times to complete the aging process. The aged slurry was filtered, and the filter cake was dried at 90℃ for 10 hours. Appropriate amounts of graphite and water were added, and the mixture was rolled and pressed into tablets. The tableted material was then cured at 70℃ for 50 hours, then the temperature was lowered to 20℃ and cured for another 30 hours. The tableted material was washed with deionized water until neutral. After washing, the tablets were dried at 100℃ for 8 hours and calcined at 360℃ for 3 hours to obtain catalyst E. The composition, pore distribution, and main properties are shown in Table 1.

[0047] Comparative Example 2

[0048] The catalyst was prepared according to Example 1 disclosed in CN107790137A. 168g of Cu(NO3)2·3H2O and 95g of AlCl3·6H2O were weighed and dissolved in 850mL of deionized water to prepare working solution A. Na2CO3 was dissolved in 1000mL of deionized water to prepare solution B. The molar ratio of sodium carbonate in solution B to copper and aluminum in solution A was 1.2. 500mL of water was added to the reaction vessel, and the temperature was raised to 60℃. Under stirring, solutions A and B were added to the reaction vessel in parallel flow. The gelation time was 1 hour, and the pH of the gel slurry was controlled at 7.4±0.2. Aging began with stirring, and 26g of nano-zinc oxide was added. The pH during aging was 7.4±0.2, the temperature was 75℃, and aging lasted for 2 hours. After aging, the material was filtered, and the filter cake was hydrothermally treated under steam containing urea. The hydrothermal treatment conditions were: a molar ratio of urea to total active metal atoms of 5:1, a temperature of 230℃, a pressure of 4.5MPa, a treatment time of 5 hours, and washing three times with clean water at 40℃. After washing, the material was dried at 110℃ for 7 hours and then calcined at 320℃ for 4 hours. The calcined material was then mixed with an appropriate amount of graphite and water and pressed into sheets to obtain catalyst F. The composition, pore distribution, and main properties are shown in Table 1.

[0049] Comparative Example 3

[0050] Following the method and composition of Example 1, no Al-containing solution was added during aging. The specific preparation process is as follows:

[0051] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare an aluminum source, in which Al accounted for 25% of the Al in the catalyst. 304 g of Cu(NO3)2·3H2O and 107 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 146 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into 5 equal portions by volume. An aluminum source was added to the reaction vessel at a reaction temperature of 62°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solution was 0.48:1. The pH was controlled at 4.8. A solution containing Cu and Al and the composite precipitant were then fed into the reaction vessel. The pH was adjusted to 10.3 five times, with each adjustment being 1.1. After each adjustment, a portion of zinc source was added. The pH of the adjusted reaction slurry was kept constant for 12 minutes to generate a gelling material containing copper, zinc, and aluminum. The resulting slurry was then... The mixture was divided into two parts. One part of the gelling material was aged at 92℃, with the aging pH controlled at 12.7 and the aging time at 2.3 hours. The volume ratio of the unaged gelling material to the gelling material obtained in step (1) was 0.41. The unaged gelling material was cooled to 15℃. After aging, the unaged gelling material was mixed with the aged gelling material and aging continued at 57℃, with the aging pH controlled at 8.2 and the aging time at 2.2 hours. The aging process was then completed. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 90℃ for 10 hours, and then a suitable amount of graphite and water were added for rolling and pressing. The cake was then washed with deionized water at room temperature until neutral. The washed cake was dried at 80℃ for 12.0 hours. The dried cake was calcined at 380℃ for 3 hours to obtain catalyst G. The composition, pore distribution, and main properties are shown in Table 1.

[0052] Comparative Example 4

[0053] The method and composition are the same as in Example 1, except that the slurry is not divided into two parts. The slurry undergoes one aging process, during which a second aluminum source is added. The specific preparation process is as follows:

[0054] AlCl3·6H2O was added to dissolving tank 1 containing deionized water to prepare the first aluminum source, in which Al accounted for 25% of the total Al in the catalyst. 304 g of Cu(NO3)2·3H2O and 73.8 g of AlCl3·6H2O were added to dissolving tank 2 containing deionized water to prepare a Cu-Al solution. 146 g of Zn(NO3)2·6H2O was added to dissolving tank 3 containing deionized water to prepare a zinc source, which was then divided into 5 equal portions by volume. AlCl3·6H2O was added to dissolving tank 4 containing deionized water to prepare the second aluminum source, in which Al accounted for 23% of the total Al in the catalyst. The first aluminum source was added to the reaction vessel at a reaction temperature of 62°C. A composite precipitant was added dropwise. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solution was 0.48:1. The pH value was controlled at 4.8. A solution containing Cu and Al and the composite precipitant were then fed into the reaction vessel. The pH value was adjusted to 10.3 five times, with each adjustment being 1.1. After each adjustment to the target value, a zinc source was added. The pH value of the adjusted reaction slurry was kept constant for 12 minutes to generate a gelling material containing copper, zinc, and aluminum. The resulting slurry was then aged. At the start of aging, a second aluminum source was added dropwise over 1.2 hours. The aging temperature was 72°C, the aging pH was controlled at 8.2, and the aging time was 2.2 hours. The aging process was then completed. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 90℃ for 10 hours, and then a suitable amount of graphite and water were added for rolling and pressing. The cake was then precipitated and washed with deionized water at room temperature until neutral. The precipitated material was dried at 80℃ for 12.0 hours. The dried precipitated material was calcined at 380℃ for 3 hours to obtain catalyst H. The composition, pore distribution, and main properties are shown in Table 1.

[0055] Comparative Example 5

[0056] Following the method and composition of Example 1, deionized water was added to the reaction vessel. The first aluminum source was no longer prepared; instead of adding Al2O3 to the catalyst via the first aluminum source, a Cu- and Al-containing solution was added. The specific preparation process is as follows:

[0057] A Cu-Al solution was prepared by dissolving 304 g of Cu(NO3)2·3H2O and 109 g of AlCl3·6H2O in deionized water in dissolving vessel 2. A zinc source was prepared by dissolving 146 g of Zn(NO3)2·6H2O in deionized water in dissolving vessel 3, and the solution was divided into 5 equal portions by volume. AlCl3·6H2O was added to dissolving vessel 3 containing deionized water to prepare an aluminum salt solution, in which Al accounted for 23% of the Al in the catalyst. Deionized water was added to the reaction vessel at a temperature of 62°C. Acetic acid solution was added dropwise to control the pH at 4.8. The molar ratio of ammonia to sodium carbonate in the ammonia and sodium carbonate solutions was 0.48:1. A solution containing Cu and Al, along with a composite precipitant, was added to the reaction vessel. The pH was adjusted to 10.3 five times, with each adjustment being 1.1. After each adjustment, a zinc source was added, and the pH of the adjusted reaction slurry was kept constant for 12 minutes to generate a gelling material containing copper, zinc, and aluminum. The resulting slurry was divided into two parts, and one part of the gelling material was taken. Aging was carried out at a temperature of 92℃, an aging pH value controlled at 12.7, and an aging time of 2.3 hours. The volume ratio of the unaged gelling material to the gelling material obtained in step (1) was 0.41. The unaged gelling material was cooled to 15℃. After aging, the unaged gelling material was mixed with the aged gelling material, and aging continued. At the beginning of aging, an aluminum salt solution was added dropwise over a period of 1.2 hours. The aging temperature was 57℃, the aging pH value controlled at 8.2, and the aging time was 2.2 hours. The aging was then stopped. The slurry obtained after aging was filtered to obtain a solid material. The filter cake was dried at 90℃ for 10 hours, and then a suitable amount of graphite and water were added for rolling and pressing. The cake was then washed with deionized water at room temperature until neutral. The washed cake was dried at 80℃ for 12.0 hours. The dried cake was calcined at 380℃ for 3 hours to obtain catalyst I. The composition, pore distribution, and main properties are shown in Table 1.

[0058] Comparative Example 6

[0059] Catalyst J was prepared using only ammonia water as a precipitant, according to the method and composition of Example 1. The composition, main properties and pore distribution are shown in Table 1.

[0060] Comparative Example 7

[0061] Catalyst K was prepared using sodium carbonate as a precipitant according to the method and composition of Example 1. The composition, main properties and pore distribution are shown in Table 1.

[0062] Example 5

[0063] The methanol synthesis catalyst was crushed to 16-40 mesh and reduced with a low-concentration hydrogen-nitrogen mixture (H2 / N2 = 2 / 97 (volume ratio)) for 16-25 hours before use, with a maximum reduction temperature of 280℃. The catalyst activity was evaluated in a micro-fixed-bed reactor. The catalyst loading was 5 ml, the feed gas composition was CO / H2 / CO2 / N2 = 15 / 68 / 5 / 12 (volume ratio), the reaction pressure was 5.0 MPa, and the space velocity was 10500 h⁻¹. -1 The reaction temperature was 235℃, and the conversion rates of CO and CO2 were determined to be the initial catalyst activity. The catalyst was then heat-treated at 430℃ for 5 hours in a synthesis atmosphere, and then cooled to 235℃ to determine the post-heat-treatment activity (i.e., heat resistance) of CO and CO2 conversion rates. The products were analyzed by gas chromatography, and the space-time yield of methanol (g·mL⁻¹) was determined. -1 ·h -1 That is, the number of grams of methanol produced per milliliter of catalyst per hour, the results are shown in Table 5.

[0064] As can be seen from Tables 1-3, the active component copper oxide in the catalyst surface phase of the present invention has a high density and good metal dispersion, and the copper particle size is small, thereby improving the synergistic effect between Cu-ZnO catalyst. The copper particle size is mainly concentrated in 5-8 nm. The catalyst has high activity and selectivity. As can be seen from the experimental results in Table 4, the methanol synthesis catalyst of the present invention has high activity, heat resistance and excellent selectivity.

[0065] Table 1. Catalyst composition and properties

[0066] Catalyst No. A B C D E F CuO, wt% 50 51 48 54 58 55 ZnO, wt% 20 22 24 21 22 25 Al203, wt.% 30 27 28 25 20 20 Specific surface area / m 2 ·g -1 ]]> 354 366 357 374 218 172 Pore volume / cm 3 ·g -1 ]]> 0.539 0.556 0.545 0.567 0.457 0.374 Pore distribution, % < 15 nm 1.85 1.94 1.86 1.71 41.17 88.73 15 nm to 20 nm 43.53 43.38 43.42 43.04 42.10 9.58 20 nm to 30 nm 4.19 3.89 4.05 3.74 15.23 1.69 30 nm to 35 nm 44.02 44.07 44.13 44.46 1.50 - > 35 nm 6.41 6.72 6.54 7.05 - - Mechanical strength, N / mm 17.9 17.8 18.1 17.7 18.5 18.6

[0067] Continued from Table 1: Catalyst Composition and Properties

[0068]

[0069]

[0070] Table 2. Average particle size, dispersion, and specific surface area of ​​copper in the catalyst surface phase.

[0071] S Cu D is the specific surface area of ​​copper. Cu Copper dispersion

[0072] Table 3. Weight ratio of surface active metal oxides to bulk active metal oxides of catalysts.

[0073]

[0074]

[0075] Continued from Table 3: Weight ratio of surface active metal oxides to bulk active metal oxides of catalysts.

[0076]

[0077]

[0078] Table 4. Results of catalyst activity evaluation and heat resistance tests

[0079]

Claims

1. A method for preparing a catalyst for syngas-to-methanol production, characterized in that... The following are included: (1) A first aluminum source with a pH value of 4.5 to 6.0 is added to a gelling tank, and then a copper-aluminum mixed solution and a composite precipitant are added to the gelling tank to carry out a gelling reaction. The pH value is controlled to increase gradually to 9.0 to 12.

5. After each increase, a zinc source is added. After the gelling reaction is completed, a gelling product is obtained. The pH value increases 2 to 10 times, preferably 3 to 8 times. (2) A portion of the gelling product obtained in step (1) is aged. The aged material is mixed with the material that has not participated in aging to obtain a mixture. (3) The mixture is aged. A second aluminum source is added during the aging process. After the aging is completed, the solid and liquid are separated. The solid phase is dried and pressed into tablets to obtain a molded product. The product is washed, dried and calcined to obtain a syngas to methanol catalyst.

2. The method according to claim 1, characterized in that: The concentration of the first aluminum source in step (1) is 2 to 100 g / L by weight, preferably 6 to 95 g / L, based on Al2O3. The aluminum source is selected from one or more aqueous solutions of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate. Based on Al2O3, the Al in the first aluminum source accounts for 10% to 40% of the Al in the catalyst, preferably 13% to 38%.

3. The method according to claim 1, characterized in that: The composite precipitant in step (1) is an ammonia solution and a sodium carbonate solution. The molar ratio of ammonia to sodium carbonate in the composite precipitant is 0.3:1 to 0.7:1, the concentration of ammonia is 5wt% to 12wt%, and the concentration of sodium carbonate solution is 8wt% to 20wt%.

4. The method according to claim 1, characterized in that: In the copper-aluminum mixed solution described in step (1), the copper salt concentration is expressed as Cu 2+ The concentration of the copper salt is 0.2–4.5 mol / L, and the weight concentration of the aluminum salt, calculated as Al2O3, is 2–100 g / L; wherein the copper salt is a copper-containing nitrate and / or acetate, and the aluminum salt is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum acetate.

5. The method according to claim 1, characterized in that: The zinc source mentioned in step (1) is an aqueous solution containing zinc nitrate and / or acetate, with a concentration expressed as Zn. 2+ The concentration is calculated to be 0.1–3.5 mol / L, preferably 0.1–3.0 mol / L; the zinc source is used to divide the solution volume into equal parts according to the incrementing number of times.

6. The method according to claim 1, characterized in that: The gelation reaction temperature in step (1) is 40-90℃; during the gelation reaction, the pH value is increased by 0.05-0.5 hours after each increment, and the pH value increment is the same or different each time.

7. The method according to claim 1, characterized in that: The volume ratio of the gelling material aged in step (2) to the gelling material obtained in step (1) is 0.20:1 to 0.50:1, preferably 0.22:1 to 0.48:

1.

8. The method according to claim 1, characterized in that: The aging conditions described in step (2) are as follows: aging temperature is 90-98℃, aging pH value is 10.5-13.8, preferably 11.0-13.5, and aging time is 1.0-5.0 hours, preferably 1.2-4.0 hours.

9. The method according to claim 1, characterized in that: The second aluminum source in step (3) has a weight concentration of 2 to 90 g / L, preferably 6 to 85 g / L, based on Al2O3. The second aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum chloride and aluminum acetate aqueous solution. Based on Al2O3, the Al in the second aluminum source accounts for 18% to 40% of the Al in the catalyst.

10. The method according to claim 1, characterized in that: The aging conditions described in step (3) are as follows: the aging temperature is 40-80℃, preferably 45-78℃, the aging pH value is 7.0-10.0, preferably 7.5-9.5, and the aging time is 1.0-4.0 hours, preferably 1.5-3.0 hours; the second aluminum source is added at the beginning of aging, and the time for adding the second aluminum source solution is 30%-70% of the aging time.

11. The method according to claim 1, characterized in that: The drying conditions for step (3) are: drying temperature of 50~150℃ and drying time of 0.5~24.0 hours; the calcination conditions are: calcination temperature of 320~450℃ and calcination time of 1~16 hours.

12. A syngas-to-methanol catalyst prepared by the method according to any one of claims 1 to 11, characterized in that: The pore volume of pores larger than 15 nm accounts for more than 91% of the total pore volume, preferably 91% to 99%.

13. The syngas-to-methanol catalyst according to claim 12, characterized in that... The pore size distribution is as follows: pores smaller than 15 nm account for 1% to 9% of the total pore volume; pores between 15 and 20 nm account for 41% to 49% of the total pore volume; pores between 20 and 30 nm account for 3% to 11% of the total pore volume; pores between 30 and 35 nm account for 42% to 50% of the total pore volume; and pores larger than 35 nm account for 5% to 13% of the total pore volume.

14. The syngas-to-methanol catalyst according to claim 12, characterized in that: Based on the weight of the catalyst, it comprises the following components: CuO 30%–68%, preferably 32%–65%, ZnO 17%–55%, preferably 19%–47%, and Al2O3 15%–53%, preferably 17%–48%.

15. The syngas-to-methanol catalyst according to claim 12, characterized in that... Specific surface area is 200–650 m² 2 / g, with a pore volume of 0.40~1.00mL / g.

16. The syngas-to-methanol catalyst according to claim 12, characterized in that... The specific surface area of ​​metallic copper in the reduced catalyst is 56–160 m². 2 / g, preferably 60-155m 2 / g; the average particle size of metallic copper is 5~8nm. The dispersion of metallic copper is 38%~65%, preferably 40%~63%.

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