Preparation method of catalyst for synthesizing methanol
Technical Field
The invention relates to a preparation method of a methanol synthesis catalyst, in particular to a preparation method of a methanol synthesis catalyst with high activity, high selectivity and good heat resistance.
Background
Methanol is increasingly regarded as a basic chemical raw material and a new energy source, is widely applied to organic synthesis, dye, fuel, medicine, coating and national defense industries, and along with the continuous increase of the demand and the production capacity of methanol along with the development of the industries in recent years, the position of methanol in national economy is more important, so that the production technology and the catalyst performance of the methanol are required to be further improved in order to further promote the development of the methanol industry.
Industrially, methanol generally contains H2、CO、CO2The synthesis gas of (a) is produced under conditions of pressure, temperature and presence of a catalyst. At present, methanol is synthesized by adopting a medium-pressure and low-pressure gas phase method in the world, and the used catalyst is basically mixed oxide of copper, zinc and aluminum. CuO, ZnO and Al in synthetic methanol catalyst2O3The three components have different functions, CuO is used as a main active component, ZnO and Al2O3Is an auxiliary agent. The addition of ZnO can make the catalyst form Cu/Zn synergetics, greatly raise activity and selectivity of catalyst, Al2O3Not only plays a role of a framework in the catalyst, but also can disperse active components in the catalyst to enable CO to be generated2The adsorption and conversion rate are improved, and a proper amount of Al is added into the copper-based catalyst2O3Can improve catalyst CO2Selectivity of synthesizing methanol by hydrogenation.
Cu/ZnO/Al2O3The activity of the catalyst is closely related to the distribution and the morphology of metals, and when the composition and the content of the catalyst are not changed, the Cu-ZnO synergistic effect and the Cu dispersibility in the catalyst play an important role in the catalytic activity and the selectivity. The catalytic theory considers that the Cu/ZnO catalyst has double active points, the oxygen vacancy on ZnO also has important influence on the catalytic performance of the catalyst (Cu-ZnO synergistic effect), the number of the oxygen vacancy is increased, the interaction between Cu and ZnO is enhanced, and the conversion rate of carbon monoxide and the selectivity of methanol are increased. The dispersion property and oxygen vacancy of the Cu/ZnO catalyst are closely related to the composition and preparation method of the catalyst, and how to improve the dispersion degree of active components of the catalyst in the preparation process of the catalyst, therebyThe purposes of improving the synergistic effect between Cu and ZnO and increasing the reaction active center are achieved, so that the activity of the catalyst is improved, and the selectivity of the catalyst is improved, which becomes the key point of the research of the copper-based catalyst.
At present, Cu/ZnO/Al2O3The synthesis method of the catalyst comprises a precipitation method, an impregnation method and a sol-gel method, and in general, in industry, a coprecipitation method (including a parallel flow method, a reverse addition method and a forward addition coprecipitation method) is firstly used for generating mixed basic carbonate of copper and zinc, then aluminum hydroxide is added in the pulping process, and the generated pulp is washed by water, dried, roasted and tabletted to form. At present, the improvement of catalyst preparation is generally in the aspects of adding auxiliary agents, selecting carriers, investigating different preparation methods, optimizing reaction conditions and the like, and the problems of poor thermal stability, low selectivity and short service life of a copper-based catalyst are solved by changing the proportion and the dispersion degree of catalyst components and the size of crystal grains, increasing the number of active sites in the catalyst, optimizing the synergistic effect of the active components and the auxiliary agents and increasing the specific surface area of the catalyst to improve the activity of the catalyst. The catalyst has different preparation methods, different dispersity of the obtained copper, different synergistic effect between the metal active center copper and the auxiliary agent, and larger difference of the performance of the obtained catalyst.
CN107185543 discloses a catalyst for synthesizing methanol by carbon dioxide hydrogenation, the catalyst is a mixture of Cu and ZnO in filiform or cylindrical form, soluble zinc salt and mineralizer are dissolved in deionized water, the solution is kept at 60-150 ℃ for 1-6 h in a high-pressure reaction kettle, and then is slowly cooled to room temperature to obtain white precipitate, and ZnO in different forms is obtained after drying; adding soluble copper salt and prepared ZnO into deionized water, adding a reducing agent for reaction, washing and drying to obtain the Cu/ZnO catalyst.
CN 1660490A discloses a preparation method of a methanol synthesis catalyst, and a small amount of surfactant OP is added in the preparation process of a coprecipitation method. CN 101733109A copper-based methanol synthesis catalyst is prepared by adding an auxiliary agent (one or more of ethylene glycol, diethylamine, glycerol, magnesium stearate, and activated carbon) during precipitation. In the method, the organic reagent is added in the precipitation process to improve the Cu-ZnO synergistic effect, but the improvement of the dispersion of the catalyst metal by the organic reagent is limited, and the Cu-ZnO synergistic effect is not obviously improved.
CN101327431 discloses a preparation method of a synthetic methanol catalyst, which comprises the steps of firstly preparing a copper-zinc coprecipitate, secondly preparing a zinc-aluminum coprecipitate with a spinel structure, thirdly preparing a copper-aluminum coprecipitate, then mixing and aging the three coprecipitates, then washing, drying, roasting, adding graphite tablets into the roasted material, and thus obtaining the synthetic methanol catalyst. The method mainly aims to improve the dispersibility of the active component copper, the auxiliary agent zinc and the carrier aluminum, but the method is complex, and precipitates prepared by three-step precipitation are mixed, so that the composition and the structure of the product are uneven, and the performance of the catalyst is influenced.
CN103801302A discloses a preparation method of a copper-zinc-containing catalyst. Introducing CO into soluble salt solution A containing zinc2Gas, reacting to generate zinc compound deposit. Introducing CO into the sodium metaaluminate solution2Gas to generate aluminum-containing precipitate, aging under stirring, adding basic copper carbonate during aging, washing, filtering, drying, roasting, tabletting and forming to obtain the copper-containing catalyst. The method improves the surface area of the catalyst, but the pore structure is not concentrated, and the material obtained by precipitation has poor cohesiveness and is not easy to be tabletted and molded.
CN103172607 discloses a copper-based catalyst for synthesizing methanol by carbon dioxide hydrogenation, a preparation method and an application thereof, wherein a precipitation solution containing zinc, aluminum and zirconium is firstly generated, a copper-containing salt solution is added into the precipitation solution, and after Cu in the precipitation solution is precipitated, aging, washing, drying and roasting are carried out to obtain the copper-containing catalyst. The method still adopts the conventional process conditions in the preparation process, improves the distribution of the active metal of the catalyst only by adding zirconium and adopting polyvinylpyrrolidone and polyethylene glycol as stabilizing agents, but does not obviously increase the number of active centers.
CN201610773534.7 discloses a preparation method of a synthetic methanol catalyst, which comprises the steps of adding a sodium metaaluminate alkaline solution and a soluble salt solution containing Cu into a reaction tank filled with purified water in a concurrent flow manner to carry out gelling reaction to generate slurry I, then dropwise adding the sodium metaaluminate alkaline solution into a soluble salt solution containing Zn to carry out gelling reaction to generate slurry II, uniformly mixing the slurry I and the slurry II, carrying out aging and filtering to obtain a material, carrying out hydrothermal treatment on the obtained material by using water vapor, adding urea during the hydrothermal treatment, and then washing, filtering, drying, roasting, tabletting and forming to obtain the catalyst. Although the content of active metal copper in the surface phase of the catalyst prepared by the method is high, the synergistic effect of copper and zinc in the catalyst is reduced under the action of water vapor pressure and the impact of water molecules.
The method changes the copper-based catalyst preparation process or adds the auxiliary agent on the basis of the copper-based catalyst preparation process to change the copper dispersibility on the reduced catalyst and improve the activity of the catalyst, but in the process of improving the copper component dispersibility, other physicochemical properties of the catalyst are influenced, and the effect of improving the active component dispersibility is not obvious.
Disclosure of Invention
In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a catalyst for synthesizing methanol. The catalyst prepared by the method has the advantages of uniform distribution of active metal copper and auxiliary agent zinc, good synergistic effect, large number of active metal active centers, and improvement of the activity, selectivity and thermal stability of the methanol synthesis catalyst and the service life of the catalyst.
The preparation method of the methanol synthesis catalyst comprises the following steps:
(1) carrying out parallel flow gelling reaction on the mixed solution A and a sodium metaaluminate solution to obtain slurry I, and then aging; (2) dropwise adding the mixed solution B and a sodium carbonate solution into the aged slurry I obtained in the step (1) in a parallel flow manner, carrying out gelling reaction to obtain slurry II, and then aging; (3) carrying out solid-liquid separation on the material obtained in the step (2), and drying, roasting and forming a solid phase to obtain a catalyst; wherein the mixed solution A is an aqueous solution containing soluble copper salt and soluble zinc salt, and the mixed solution B is an aqueous solution containing soluble copper salt and soluble aluminum salt.
In the mixed solution A in the step (1), the concentration of the soluble copper salt is Cu2+1.0 to 5.0mol/L, preferably 1.5 to 4.0mol/L, and the concentration of the soluble zinc salt is Zn2+The amount of the compound is 0.5 to 6.0mol/L, preferably 1.0 to 4.0 mol/L. The copper content in the mixed solution A is 40-80%, preferably 55-75% of the copper content in the catalyst. The soluble copper salt is nitrate and/or acetate containing copper, and the soluble zinc salt is nitrate and/or acetate containing zinc.
The concentration of the sodium metaaluminate solution in the step (1) is Al2O3The amount is 10 to 90g/L, preferably 15 to 70 g/L.
The gelling reaction in the step (1) is generally carried out in a reaction tank, and the gelling reaction conditions are as follows: the reaction temperature is 30-80 ℃, preferably 40-70 ℃, the reaction time is 0.2-2.0 hours, preferably 0.5-1.5 hours, and the pH value is 6.0-9.0, preferably 6.5-8.5.
The aging conditions of the slurry I in the step (1) are as follows: the aging temperature is 40-90 ℃, preferably 50-80 ℃, the pH value is 6.0-8.0, preferably 6.5-7.5, and the aging time is 0.2-1.0 hour, preferably 0.3-0.8 hour. The aging is carried out under stirring, the preferred stirring conditions being as follows: the stirring speed is 100-300 rpm, preferably 150-250 rpm.
In the mixed solution B in the step (2), the concentration of the soluble copper salt is Cu2+0.5 to 4.0mol/L, preferably 1.0 to 3.0mol/L, and the concentration of the soluble aluminum salt is Al3+The amount of the compound is 0.5 to 5.0mol/L, preferably 1.0 to 3.5 mol/L. The soluble copper salt is nitrate and/or acetate containing copper, and the soluble aluminum salt is one or more selected from aluminum nitrate, aluminum sulfate, aluminum chloride or aluminum acetate. The copper content in the mixed solution B is 20-60% of the copper content in the catalyst, and preferably 25-45%; the aluminum content in the mixed solution B is 15-55%, preferably 20-45% of the aluminum content in the catalyst.
In the reaction material in the step (2), the molar ratio of the amount of the sodium carbonate to the total amount of copper and zinc is 0.5-4.0, preferably 1.0-3.0.
The gelling reaction conditions in the step (2) are as follows: the reaction temperature is 30-90 ℃, preferably 40-80 ℃, the reaction time is 1.5-4.0 hours, preferably 1.5-3.5 hours, the pH value is 8.5-12.0, preferably 9.0-11.0, and the pH value is at least 1.0 higher than that of the gelling reaction in the step (1), preferably at least 1.5 higher.
The aging conditions of the slurry II in the step (2) are as follows: the aging temperature is 40-90 ℃, preferably 50-80 ℃, the aging time is 1.5-6.0 hours, preferably 2.0-5.0 hours, the pH value is 7.5-11.0, preferably 8.0-10.0, and the pH value is at least 0.5 higher than the pH value aged in the step (1), preferably at least 1.0 higher. The aging is carried out under stirring, the preferred stirring conditions being as follows: the stirring speed is 300-500 rpm, preferably 300-450 rpm.
The solid-liquid separation process in the step (3) generally comprises conventional washing and filtering processes, the washing is generally washed by deionized water, and the washing temperature is controlled to be 30-80 ℃, preferably 35-65 ℃. The number of washing is 1 to 8, preferably 2 to 6.
The drying temperature in the step (3) is 50-150 ℃, preferably 60-120 ℃, and the drying time is 0.5-24 hours, preferably 1-16 hours. The roasting temperature is 300-360 ℃, and the roasting time is 1-16 hours, preferably 2-10 hours.
The methanol synthesis catalyst prepared by the method comprises the following components by weight: 20 to 65 percent of CuO, preferably 25 to 60 percent of CuO, 15 to 40 percent of ZnO, preferably 15 to 35 percent of ZnO, and Al2O35 to 40 percent, preferably 10 to 35 percent.
The properties of the methanol synthesis catalyst are as follows: the specific surface area is 100-550 m2The pore volume is 0.20-0.80 ml/g, and the pore size distribution is as follows: the pore volume of the pores with the diameter of less than 10nm accounts for 3-27% of the total pore volume, the pore volume of the pores with the diameter of 10-15 nm accounts for 58-85% of the total pore volume, the pore volume of the pores with the diameter of more than 15nm accounts for 1-15% of the total pore volume, and the preferable pore size distribution is as follows: the pore volume of the pores with the diameter of less than 10nm accounts for 7-23% of the total pore volume, the pore volume of the pores with the diameter of 10-15 nm accounts for 65-80% of the total pore volume, and the pore volume of the pores with the diameter of more than 15nm accounts for 5-13% of the total pore volume.
The specific surface area of the metal copper in the reduced catalyst is 35-120 m2Preferably 40 to 100 m/g2(ii) in terms of/g. The dispersion degree of the metallic copper is 13 to 45 percent, and preferably 18 to 40 percent.
The synthetic methanol catalyst prepared by the method is applied to the synthetic methanol reaction, and the general process conditions are as follows: the reaction temperature is 210-320 ℃, and preferably 230-280 ℃; the pressure is 2-10 MPa, preferably 2-7 MPa; the volume airspeed is 2000-15000 h-1Preferably 4000 to 12000 h-1。
Compared with the prior art, the active metal of the catalyst prepared by the method is more dispersed, the Cu-ZnO synergistic effect is good, the pore distribution of the catalyst is concentrated (mainly concentrated at 10-15 nm), and the catalyst has the characteristics of high activity, high selectivity and heat resistance.
The method comprises the steps of precipitating step by step, firstly carrying out co-current flow of a mixed solution containing partial Cu and Zn and a sodium metaaluminate solution for coprecipitation reaction, carrying out primary aging on Cu, Zn and Al and a mixture slurry to generate a primary precipitate containing oxides of Cu, Zn and Al with larger particles, then adding the residual mixed solution of Cu and Al and a sodium carbonate solution into the aged slurry in a co-current flow manner, then carrying out deep aging to prepare a copper, zinc and aluminum mixed precipitate, and finally preparing the copper-zinc catalyst. By regulating and controlling the preparation steps and preparation conditions, in the process of growing up copper, zinc and aluminum mixed precipitate particles, active metal in the previously deposited metal oxide precursor has a certain anchoring effect on the subsequently deposited active metal, different active metals are orderly deposited in the catalyst, the growth speed of the metal oxide particles and the probability of mutual contact among the active metals are controlled, the dispersion degree of copper is improved, the Cu-ZnO synergistic effect is increased, the active center is greatly improved, and Al generated by different aluminum sources in the precipitation process is simultaneously used2O3Has good skeleton effect, leads the main active component copper and the auxiliary agent zinc to be dispersed more evenly, and is beneficial to improving the activity of the catalyst, the selectivity of methanol and the thermal stability. Meanwhile, the method also enables the catalyst to form a more appropriate pore structure, the pore distribution is reasonable, and the specific surface area and the pore volume of the catalyst are improved.
Detailed Description
The invention is further illustrated by the following examplesThe scheme and the effect of (1). In the present invention, the specific surface area, pore volume and pore distribution are measured by a low-temperature liquid nitrogen adsorption method, and the specific surface area (S) of the catalyst metal Cu after reduction is measuredCu) And degree of dispersion (D)Cu) By using N2Determined by O-chemisorption. v% is volume fraction and wt% is mass fraction.
Example 1
Adding Cu (NO)3)2·3H2O、Zn(NO3)2·6H2Dissolving O in deionized water to prepare mixed solution A, Cu2+The concentration is 2.8mol/L, Zn2+The concentration was 2.5 mol/L. Adding Cu (NO)3)2·3H2O and AlCl3·6H2Dissolving O in deionized water to prepare mixed solution B, Cu2+Concentration of 1.8mol/L, Al3+The concentration was 2.0 mol/L. Adding deionized water into the reaction tank, and adding sodium metaaluminate solution (containing Al)2O342 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 60 ℃, the gelling pH value is 7.5, and the gelling time is 1.0 hour, thus obtaining slurry I. And ageing the slurry I under stirring, wherein the stirring speed is 200 rpm, the ageing temperature is 75 ℃, the pH value is 7.0, and the ageing time is 0.7 hour. After the aging is finished, adding the mixed solution B and a sodium carbonate solution into the aged slurry I in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.0, the gelling temperature is 60 ℃, the pH value is 9.2, and the gelling time is 2.0 hours, so as to obtain slurry II, aging the slurry II under the stirring condition, wherein the stirring speed is 380 r/m, the aging temperature is 75 ℃, the pH value is 8.5, and the aging time is 3.0 hours, filtering the aged slurry II, washing a filter cake for 3 times with deionized water, drying the filter cake at 100 ℃ for 10 hours, roasting at 360 ℃ for 3 hours, adding a proper amount of graphite into the roasted material, and pressing the calcined material into sheets to obtain the catalyst A. The composition, pore distribution and main properties are shown in table 1.
Example 2
Cu (NO) was added in the amount shown in Table 1 according to the catalyst B in example 13)2·3H2O、Zn(NO3)2·6H2Dissolving O in deionized water to obtain mixed solution A, and dissolving Cu (NO)3)2·3H2O and Al (NO)3)3·9H2Dissolving O in deionized water to prepare a mixed solution B. Adding deionized water into the reaction tank, and adding sodium metaaluminate solution (containing Al)2O345 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 55 ℃, the gelling pH value is 7.2, and the gelling time is 0.8 hour, so as to obtain slurry I. And ageing the slurry I under stirring, wherein the stirring speed is 210 rpm, the ageing temperature is 72 ℃, the ageing pH value is 6.8, and the ageing time is 0.5 hour. After the aging is finished, adding the mixed solution B and a sodium carbonate solution into the slurry I in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.4, the gelling temperature is 53 ℃, the pH value is 9.4, the gelling time is 2.3 hours, so as to obtain slurry II, aging the slurry II under the stirring condition, the stirring speed is 420 revolutions per minute, the aging temperature is 76 ℃, the aging pH value is 8.8, and the aging time is 3.0 hours, filtering the aged slurry II, washing a filter cake with deionized water for 4 times, drying the filter cake at 80 ℃ for 12 hours, roasting at 350 ℃ for 4 hours, adding a proper amount of graphite and water pressure into the roasted material, so as to obtain the catalyst B. The composition, pore distribution and main properties are shown in table 1.
Example 3
Cu (NO) was added in the amount shown in Table 1 according to the catalyst C in example 13)2·3H2O、Zn(NO3)2·6H2Dissolving O in deionized water to obtain mixed solution A, and dissolving Cu (NO)3)2·3H2O and Al2(SO4)3·18H2Dissolving O in deionized water to prepare a mixed solution B. Adding deionized water into the reaction tank, and adding sodium metaaluminate solution (containing Al)2O352 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 45 ℃, the pH value is 7.8, and the gelling time is 1.2 hours, thus obtaining slurry I. And ageing the slurry I under stirring, wherein the stirring speed is 230 rpm, the ageing temperature is 73 ℃, the ageing pH value is 7.1, and the ageing time is 0.6 hour. After aging, adding the mixed solution B and a sodium carbonate solution into the slurry I in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 1.8, the gelling temperature is 52 ℃, the gelling pH value is 9.7, and gelling is carried out during gellingAging the slurry II under the stirring condition with the stirring speed of 410 rpm, the aging temperature of 73 ℃, the aging pH value of 9.2 and the aging time of 4.0 hours, filtering the aged slurry II, washing a filter cake with deionized water for 5 times, drying the filter cake at 110 ℃ for 10 hours, roasting at 340 ℃ for 4 hours, adding a proper amount of graphite into the roasted material and pressing the roasted material into sheets to obtain the catalyst C. The composition, pore distribution and main properties are shown in table 1.
Example 4
Cu (NO) was added in the amount shown in Table 1 according to the method of example 1, based on the catalyst D composition3)2·3H2O、Zn(NO3)2·6H2Dissolving O in deionized water to obtain mixed solution A, and dissolving Cu (NO)3)2·3H2O and AlCl3·6H2Dissolving O in deionized water to prepare a mixed solution B. Adding deionized water into a reaction tank, and adding sodium metaaluminate solution (containing Al)2O356 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 47 ℃, the pH value is 7.5, and the gelling time is 0.9 hour, thus obtaining slurry I. And ageing the slurry I under stirring, wherein the stirring speed is 190 rpm, the ageing temperature is 72 ℃, the ageing pH value is 6.6, and the ageing time is 0.8 hour. After the aging is finished, adding the mixed solution B and a sodium carbonate solution into the slurry I in a cocurrent manner, controlling the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc to be 2.2, the gelling temperature to be 45 ℃, the gelling pH value to be 10.0, controlling the gelling time to be 2.6 hours, obtaining slurry II, aging the slurry II under the stirring condition, controlling the stirring speed to be 370 r/min, the aging temperature to be 71 ℃, controlling the pH value to be 9.3, controlling the aging time to be 4.2 hours, filtering the aged slurry II, washing a filter cake with deionized water for 4 times, drying the filter cake at 90 ℃ for 14 hours, roasting the filter cake at 350 ℃ for 4 hours, adding a proper amount of graphite into the roasted material, and pressing the calcined material into sheets under water pressure, thus obtaining the. The composition, pore distribution and main properties are shown in table 1.
Comparative example 1
Mixing Cu (NO) according to the component content of the catalyst E in the table 13)2·3H2O、Zn(NO3)2·6H2O and AlCl3·6H2O is dissolved in the deionized waterPreparing a mixed solution in the sub-water. Adding deionized water into a reaction tank, adding the mixed solution and a sodium carbonate solution into the reaction tank in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.0, the gelling temperature is 60 ℃, the gelling time is 3 hours, and the reaction pH value is 7.6, so as to obtain reaction slurry. Aging the slurry under the condition of stirring, wherein the aging pH value is 7.8, the aging temperature is 75 ℃, the aging time is 3.7 hours, filtering the aged slurry, washing a filter cake for 3 times by deionized water, drying the filter cake for 10 hours at 100 ℃, roasting for 3 hours at 360 ℃, adding a proper amount of graphite into the roasted material, and pressing the mixture into sheets by water to obtain the catalyst E. The composition, pore distribution and main properties are shown in table 1.
Comparative example 2
Mixing Cu (NO) according to the component content of the catalyst F in the table 13)2·3H2O and Zn (NO)3)2·6H2Dissolving O in deionized water to prepare a mixed solution. Adding deionized water into a reaction tank, and adding sodium metaaluminate solution (containing Al)2O342 g/L) and the mixed solution are added into a reaction tank in parallel, the gelling temperature is 60 ℃, the gelling time is 3 hours, and the reaction pH value is 7.6, so as to obtain reaction slurry. Aging the slurry under the condition of stirring, wherein the aging pH value is 7.8, the aging temperature is 75 ℃, the aging time is 3.7 hours, filtering the aged slurry, washing a filter cake for 3 times by deionized water, drying the filter cake for 10 hours at 100 ℃, roasting for 3 hours at 360 ℃, adding a proper amount of graphite into the roasted material, and pressing the mixture into sheets by water to obtain the catalyst F. The composition, pore distribution and main properties are shown in table 1.
Comparative example 3
Mixing Cu (NO) according to the component content of the catalyst G in the table 13)2·3H2Dissolving O in deionized water to prepare solution A. Adding Zn (NO)3)2·6H2Dissolving O in deionized water to prepare solution B. Deionized water is added into the reaction tank 1, and sodium metaaluminate solution (containing Al) is added2O342 g/L) and the solution A are added into a reaction tank 1 in parallel, the gelling temperature is 60 ℃, the gelling pH value is 7.5, and the gelling time is 1.0 hour, thus obtaining slurry I. Adding deionized water into the reaction tank 2, and adding sodium metaaluminate solution(containing Al)2O342G/L) and the solution B are added into a reaction tank 2 in a parallel flow mode, the gelling temperature is 60 ℃, the gelling pH value is 9.2, the gelling time is 2.0 hours, slurry II is obtained, the slurry I and the slurry II are mixed, the mixed slurry is aged under the condition of stirring, the aging pH value is 7.8, the aging temperature is 75 ℃, the aging time is 3.7 hours, the aged slurry is filtered, deionized water is used for washing a filter cake for 3 times, the filter cake is dried for 10 hours at 100 ℃, roasting is carried out for 3 hours at 360 ℃, a proper amount of graphite and water pressure are added into the roasted material for forming a sheet, and a catalyst G is obtained. The composition, pore distribution and main properties are shown in table 1.
Comparative example 4
Mixing Cu (NO) according to the component content of catalyst H in the table 13)2·3H2O and AlCl3·6H2Dissolving O in deionized water to obtain mixed solution A, and dissolving Zn (NO)3)2·6H2O and AlCl3·6H2Dissolving O in deionized water to prepare a mixed solution B, adding the deionized water into a reaction tank 1, adding the mixed solution A and a sodium carbonate solution into the reaction tank in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.0, the gelling temperature is 60 ℃, the gelling pH value is 7.5, and the gelling time is 1.0 hour, thus obtaining slurry I. Adding deionized water into a reaction tank 2, adding a mixed solution B and a sodium carbonate solution into the reaction tank 2 in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.0, the gelling temperature is 60 ℃, the gelling pH value is 9.2, and the gelling time is 2.0 hours, so as to obtain a slurry II, mixing the slurry I and the slurry II, aging the mixed slurry under stirring, wherein the aging pH value is 7.8, the aging temperature is 75 ℃, the aging time is 3.7 hours, filtering the aged slurry, washing a filter cake for 3 times by using the deionized water, drying the filter cake for 10 hours at 100 ℃, roasting for 3 hours at 360 ℃, adding a proper amount of graphite into the roasted material, and pressing the mixture into sheets by using water, so as to obtain a catalyst H. The composition, pore distribution and main properties are shown in table 1.
Comparative example 5
Mixing Cu (NO) according to the component content ratio of catalyst I in Table 13)2·3H2O、Zn(NO3)2·6H2O is dissolved in deionized water to prepareThe solution A was mixed. Adding Cu (NO)3)2·3H2O and AlCl3·6H2Dissolving O in deionized water to prepare a mixed solution B. Adding deionized water into the reaction tank, and adding sodium metaaluminate solution (containing Al)2O342 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 60 ℃, the gelling pH value is 7.5, and the gelling time is 1.0 hour, thus obtaining slurry I. Adding the mixed solution B and a sodium carbonate solution into slurry I which is not aged in a cocurrent manner, wherein the molar ratio of the amount of sodium carbonate to the total amount of copper and zinc is 2.0, the gelling temperature is 60 ℃, the pH value is 9.2, the gelling time is 2.0 hours, so as to obtain slurry II, aging the slurry II under the stirring condition, the aging temperature is 75 ℃, the aging pH value is 7.8, and the aging time is 3.7 hours, filtering the aged slurry, washing a filter cake for 3 times by deionized water, drying the filter cake at 100 ℃ for 10 hours, roasting at 360 ℃ for 3 hours, adding a proper amount of graphite into the roasted material, pressing the roasted material into sheets by water, and thus obtaining the catalyst I. The composition, pore distribution and main properties are shown in table 1.
Comparative example 6
Reference J, having the same composition as the catalyst of example 1, was prepared according to the method disclosed in CN201610773534.7, by the following procedure:
cu (NO) with the catalyst composition of example 13)2·3H2Dissolving O in deionized water to prepare solution A. Adding Zn (NO)3)2·6H2Dissolving O in deionized water to prepare a mixed solution B. Adding deionized water into the reaction tank, and adding sodium metaaluminate solution (containing Al)2O342 g/L) and the mixed solution A are added into a reaction tank in parallel, the gelling temperature is 60 ℃, the gelling pH value is 7.5, and the gelling time is 1.0 hour, so that copper-containing and aluminum-containing precipitate slurry I is obtained. Sodium metaaluminate solution (containing Al)2O342 g/L) is added into the solution B under stirring, the gelling temperature is kept at 60 ℃, the pH value is controlled at 7.5 when the gelling is finished, and the gelling time is controlled at 2 hours, thereby generating zinc and aluminum containing precipitate slurry II. The two types of slurry containing precipitates were mixed. Aging under stirring at pH 7.8 and 75 deg.C for 3.7 hr, filtering, and hydrothermal filtering under urea-containing water vaporThe conditions of the treatment and the hydrothermal treatment are as follows: the mol ratio of the total amount of the urea and the active metal atoms is 7:1, the temperature is 230 ℃, the pressure is 6.0MPa, the processing time is 4 hours, the filter cake is washed by deionized water for 3 times, the filter cake is dried for 10 hours at 100 ℃, roasted for 3 hours at 360 ℃, and a proper amount of graphite and water are added into the roasted material to press the material into sheets, so that the catalyst J is obtained. The composition, pore distribution and main properties are shown in table 1.
Example 5
Grinding the synthetic methanol catalyst to 16-40 mesh, and using low concentration hydrogen (H) before use2/N2And (vol) = 3/97) reducing the mixed gas of hydrogen and nitrogen for 16-25 h, wherein the maximum reduction temperature is 235 ℃. The activity of the catalyst was evaluated on a miniature fixed bed reactor. The loading of the catalyst is 5ml, and the composition of the raw material gas is CO/H2/CO2/N2=12/70/6/12 (volume ratio), reaction pressure is 5.0MPa, space velocity is 10000h-1The reaction temperature was 250 ℃ and CO were measured2The conversion of (a) is the initial activity of the catalyst. Then the catalyst is heat treated for 5h at 440 ℃ in the synthetic atmosphere, and then the temperature is reduced to 250 ℃ for measuring CO and CO2The conversion of (b) is activity after heat treatment, i.e., heat resistance. The product was analyzed by gas chromatography to give a space-time yield of g.mL of methanol-1·h-1I.e., grams of methanol produced per milliliter of catalyst per hour, the results are shown in table 2.
As can be seen from tables 1 and 2, the catalyst of the present invention has good metal dispersion, thereby improving the synergistic effect between Cu and ZnO, more concentrated pore structure distribution, mainly concentrated in 10nm to 15nm, and high activity and selectivity of the catalyst in the pore distribution range.
TABLE 1 catalyst composition and Properties
TABLE 1 (continuation)
TABLE 2 degree of dispersion and specific surface area of metallic copper
SCuIs the specific surface area of copper, DCuIs degree of dispersion of copper
TABLE 3 evaluation of catalyst Activity and Heat resistance test results