CN116371396A - Catalyst, preparation method thereof and isoprene synthesis method - Google Patents

Catalyst, preparation method thereof and isoprene synthesis method Download PDF

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CN116371396A
CN116371396A CN202310399586.2A CN202310399586A CN116371396A CN 116371396 A CN116371396 A CN 116371396A CN 202310399586 A CN202310399586 A CN 202310399586A CN 116371396 A CN116371396 A CN 116371396A
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catalyst
transition metal
solution
metal oxide
isoprene
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白晨曦
郭俞彤
祁彦龙
崔龙
杨超
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Changchun Institute of Applied Chemistry of CAS
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Changchun Institute of Applied Chemistry of CAS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
    • C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
    • C07C2/867—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an aldehyde or a ketone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts

Abstract

The invention relates to the field of diene synthesis, in particular to a catalyst, a preparation method thereof and a synthesis method of isoprene. The invention provides a catalyst, which comprises a carrier, and a first transition metal oxide, a second transition metal oxide and a rare earth metal oxide which are loaded on the carrier; the first transition metal and the second transition metal are not the same; the first transition metal oxide is TiO 2 . The catalyst provided by the invention has high formaldehyde conversion rate, isobutene selectivity and isoprene yield when being used for synthesizing isoprene. Experiments show that the formaldehyde conversion rate, the isobutene selectivity and the isoprene yield of the catalyst provided by the invention are far higher than those of the comparative exampleWherein Zr-Gd/TiO 2 ‑SiO 2 The formaldehyde conversion rate of the catalyst is up to 95%, the isobutene selectivity is up to 76%, and the isoprene yield is up to 50%.

Description

Catalyst, preparation method thereof and isoprene synthesis method
Technical Field
The invention relates to the field of diene synthesis, in particular to a catalyst, a preparation method thereof and a synthesis method of isoprene.
Background
Isoprene (C) 5 H 8 ) Is a monomer of many artificial synthetic rubbers, wherein cis-1, 4-polyisoprene rubber is one of the synthetic rubbers with optimal performance, can replace natural rubber, and is also a raw material of synthetic vitamins, carotene, pesticides, spices, lubricants, vulcanizing agents and the like. It follows that isoprene has a significant impact on people's daily life and social development. With the progress of the age, the demand of isoprene is gradually increased day by day, only isoprene in C5 fraction resources is utilized, the yield of the isoprene cannot meet the demand of people, and the development of a new synthetic isoprene route becomes a focus of social attention. The existing method for producing isoprene is mainly a two-step method, but the method has the problems of low raw material selectivity, serious equipment corrosion, difficult separation of products and catalysts, serious environmental pollution and the like, and the gas phase one-step method is a multiphase reaction and is easy to separate, and meanwhile, the method has the advantages of low equipment requirement, simple operation, short process flow, capability of improving the raw material selectivity and the like, so that the method is focused and researched by vast scientific researchers.
The gas phase one-step method mainly adopts heterogeneous catalysts for reaction, wherein the heterogeneous catalysts comprise metal oxide catalysts, supported catalysts, molecular sieve catalysts and the like. At present, the traditional supported catalyst is Cr-P/SiO 2 But is itself toxic, pollutes the environment, has high preparation cost and short catalytic life. Xu Shan discloses a supported acid-base bifunctional catalyst, wherein the formaldehyde selectivity can reach 90.7%, and the conversion rate can reach 85.3%, and the catalyst is characterized in that the acid-base synergistic result of the catalyst is achieved by carrying alkali metal elements and ammonia water alkaline washing, but a large amount of ammonia water alkaline washing of catalyst intermediates is needed in the preparation process, so that the environment is polluted, and the catalyst is not beneficial to industrial production (CNIO 6563459A). Therefore, although the supported catalyst has the advantages of simple preparation, low cost and the like compared with most catalysts, the preparation process of the supported catalyst can pollute the environment, which limits the industrial application of the supported catalyst, and the development of the environment-friendly catalyst with good catalytic performance is urgent.
In addition, although it is possible toBy introducing a carrier, e.g. SiO 2 Improving the catalytic performance of the catalyst, but the transition metal element exists in SiO 2 The risk of unregulated surface dispersion forms, which limits low cost, pollution-free SiO 2 Application in the field of olefine aldehyde condensation.
Disclosure of Invention
In view of the above, the technical problem to be solved by the invention is to provide a catalyst, a preparation method thereof and a synthesis method of isoprene, wherein the catalyst provided by the invention has high formaldehyde conversion rate, isobutene selectivity and isoprene yield when being used for synthesizing isoprene.
The invention provides a catalyst, which comprises a carrier, and a first transition metal oxide, a second transition metal oxide and a rare earth metal oxide which are loaded on the carrier;
the first transition metal and the second transition metal are not the same;
the first transition metal oxide is TiO 2 。
The catalyst of the invention comprises a carrier selected from SiO 2 、γ-Al 2 O 3 MgO, caO, mnO or BaO, preferably selected from SiO 2 Or gamma-Al 2 O 3 。
The catalyst comprises a first transition metal oxide which is TiO and is supported on the carrier 2 。TiO 2 Form firm bond with the surface of the carrier, reduce the loss of metal element in the course of reaction, lengthen catalyst life-span; tiO (titanium dioxide) 2 The dispersion form of the transition metal oxide on the surface of the transition metal oxide can be flexibly adjusted; tiO (titanium dioxide) 2 The acid content and the total acid content of rare earth metal oxide in the catalyst are properly reduced, the occurrence of side reaction is reduced, and the conversion rate of raw materials is improved. In certain embodiments of the invention, the loading of the first transition metal is from 5% to 50%, preferably from 10% to 20%.
The catalyst of the present invention further comprises a second transition metal oxide and a rare earth metal oxide supported on the support. The second transition metal is selected from Pd, zr, cs, mo, V, cu, zn, cr, fe, co or Ni, preferably selected from Pd, cs, mo, V, cu or one of Zr and the like, and most preferably selected from Zr; the rare earth metal oxide is selected from La, ce, rb, pr, gd, er, tm, sm, tb or Ho, preferably from one of La, ce or Gd, more preferably from Ce or Gd, most preferably from Gd. In certain embodiments of the invention, the loading of the second transition metal oxide is from 0.1% to 10%, preferably from 1% to 2%; the loading of the rare earth metal oxide is 0.1% -10%, preferably 1% -2%.
The invention provides a preparation method of the catalyst, which comprises the following steps:
step 1) mixing a titanium source solution and a carrier, and performing first calcination;
step 2) mixing a second transition metal source, a rare earth metal source and the product obtained in the step 1), and performing second calcination to obtain the catalyst.
The invention first prepares a titanium source solution. Specifically, the invention mixes a titanium source and an organic solvent, adjusts pH to acidity, and obtains a titanium source solution. In certain embodiments of the present invention, the present invention mixes a titanium source with an organic solvent, and adds an organic acid and a mixed solution of the organic solution thereto to adjust the pH to be acidic, thereby obtaining a titanium source solution.
The titanium source is at least one of tetrabutyl titanate, dibutyl titanate, diethyl titanate and the like; the organic solvent is at least one selected from ethanol, methanol, isopropanol or glycol; the organic acid is at least one selected from glacial acetic acid, salicylic acid, citric acid, 5-sulfosalicylic acid, malic acid or oxalic acid, preferably at least one selected from glacial acetic acid, 5-sulfosalicylic acid or oxalic acid. The volume ratio of the titanium source to the organic solvent is 1: (1 to 50), preferably 1: (10-15). The concentration of the organic acid in the invention is 0.01mol/L to 2mol/L, preferably 0.01mol/L.
The pH will affect the crystal form and particle size of the first calcined product of the titanium source solution. The pH of the titanium source solution of the present invention is 1 to 6, preferably 1.3 to 4.8. In one embodiment, tetrabutyl titanate is slowly dripped into absolute ethyl alcohol under magnetic stirring to be mixed to obtain a uniform pale yellow solution, and then the mixed solution of the organic acid and the organic solution is slowly dripped into the pale yellow solution under stirring to adjust the pH of the solution to obtain a titanium source solution.
After the titanium source solution is prepared, the titanium source solution and the carrier are treated by adopting an equal-volume impregnation method. Specifically, after the titanium source solution is prepared, the titanium source solution and the carrier are mixed and subjected to first calcination. In some embodiments of the invention, the method comprises immersing the carrier in the titanium source solution, standing at room temperature, oven drying, calcining for the first time, and grinding to obtain the nano TiO with attached surface 2 Is a carrier of (a). The carrier is treated with neutral deionized water before use to remove surface impurities. In one embodiment, the invention is to dip the carrier in the titanium source solution, stand for 24 hours at room temperature, dry for 12 hours at 120 ℃ and perform the first calcination. The temperature of the first calcination is 300-1000 ℃, and the time of the first calcination is 2-8 hours; the temperature of the first calcination is preferably 500-700 ℃, and the time of the first calcination is preferably 5h. The loading of the product of the titanium source solution in the carrier after the first calcination is 5% to 50%, preferably 10% to 20%.
The support according to the invention requires a washing treatment before step 1) is carried out. Specifically, the carrier is immersed in boiling water and then calcined, thereby obtaining a carrier after the washing treatment. In some embodiments of the invention, the carrier is boiled in neutral deionized water for 1h, rinsed 3 times with cold deionized water, dried at 120 ℃, and baked at 500 ℃ for 5h to obtain the carrier after the cleaning treatment.
After the first calcination, the second transition metal source, the rare earth metal source and the product obtained in the step 1) are mixed, and the second calcination is carried out, so that the catalyst is obtained. Mixing a second transition metal source, a rare earth metal source and the product obtained in the step 1) through an isovolumetric impregnation method; specifically, the invention drops the aqueous solution of the second transition metal source and the rare earth metal source in the product obtained in the step 1), stands at normal temperature, dries, and carries out second calcination to obtain the catalyst. In some embodiments of the invention, the second transition metal source is dissolved in water, and is subjected to ultrasonic dispersion for 5min to obtain an aqueous solution of the second transition metal, and the rare earth metal source is dissolved in the aqueous solution of the second transition metal, and is subjected to ultrasonic dispersion for 5min to obtain an aqueous solution of the second transition metal source and the rare earth metal source; and (2) dripping the aqueous solution of the second transition metal source and the rare earth metal source into the product obtained in the step (1), standing at normal temperature, drying, performing second calcination, and grinding into powder to obtain the catalyst.
The second transition metal source is at least one of soluble salts such as vanadium tetrachloride, zinc nitrate, chromium nitrate hexahydrate, ferric chloride, cobalt carbonate, nickel nitrate, zirconyl nitrate, palladium chloride, palladium nitrate, cesium carbonate, ammonium molybdate tetrahydrate, copper nitrate and the like; the rare earth metal source is at least one of soluble salts such as lanthanum nitrate, cerium chloride, ceric ammonium nitrate, gadolinium nitrate, antimony chloride, praseodymium sulfate, erbium chloride, thulium nitrate, terbium chloride, holmium trichloride and the like.
The temperature of the second calcination is 300-1000 ℃, and the time of the second calcination is 2-8 hours; the temperature of the second calcination is preferably 500-700 ℃, and the time of the second calcination is preferably 5h. The loading amount of the product of the second transition metal source in the carrier after the second calcination is 0.1-10%, preferably 1-2%; the loading of the product of the rare earth metal source in the carrier after the second calcination is 0.1 to 10%, preferably 1 to 2%. The preparation method of the catalyst provided by the invention has the advantages of simple process, low-cost and easily-obtained raw materials, no toxicity, capability of meeting the industrial production requirements and compliance with the environment-friendly concept.
The invention also provides a synthesis method of isoprene, which comprises the following steps:
under the action of the catalyst, formaldehyde and isobutene react to obtain isoprene.
The invention adopts a gas phase one-step method to synthesize isoprene, and the gas phase one-step method has the advantages of short reaction flow, lower requirements on equipment as compared with a liquid phase method, low cost and the like. In certain embodiments of the invention, the invention uses formaldehyde and isobutene as raw materials and nitrogen as a carrier under the action of the catalyst, and performs Prins reaction in a fixed bed reactor at high temperature and normal pressure to obtain isoprene. The filling amount of the catalyst is 0.5 mL-5 mL. Before the reaction, the catalyst is treated in nitrogen atmosphere of 50mL/min at 200-600 deg.c for 2-5 hr to eliminate residual impurity and ensure the smooth passage of the reactant and product.
The dosage mass ratio of formaldehyde, isobutene and catalyst is (0.05-0.5): (50-150): (0.5-5). In one embodiment, the formaldehyde is fed at a rate of 0.05mL/min to 0.5mL/min; the feeding rate of the isobutene is 50 mL/min-150 mL/min; the flow rate of the nitrogen is 10 mL/min-60 mL/min. In one embodiment, the temperature of the reaction is 200 ℃ to 600 ℃.
The invention provides a catalyst, which comprises a carrier, and a first transition metal oxide, a second transition metal oxide and a rare earth metal oxide which are loaded on the carrier; the first transition metal and the second transition metal are not the same; the first transition metal oxide is TiO 2 . The catalyst provided by the invention has high formaldehyde conversion rate, isobutene selectivity and isoprene yield when being used for synthesizing isoprene. Experiments show that the formaldehyde conversion rate, the isobutene selectivity and the isoprene yield of the catalyst provided by the invention are far higher than those of a comparative example, wherein Zr-Gd/TiO 2 -SiO 2 The formaldehyde conversion rate of the catalyst is up to 95%, the isobutene selectivity is up to 76%, and the isoprene yield is up to 50%.
Drawings
FIG. 1 shows SiO as a catalyst according to the present invention 2 A preparation flow chart when the carrier is used;
FIG. 2 is a schematic diagram of an apparatus for synthesizing isoprene.
Detailed Description
The invention discloses a catalyst, a preparation method thereof and a synthesis method of isoprene. Those skilled in the art can, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced and practiced with modification and alteration and combination of the methods and applications herein without departing from the spirit and scope of the invention.
The preparation steps of the catalyst provided by the invention are shown in figure 1, and figure 1 shows that the catalyst provided by the invention uses SiO 2 Is a preparation flow chart of the carrier. In the invention, isoprene is prepared by the provided catalyst, as shown in fig. 2, and fig. 2 is a device diagram for synthesizing isoprene.
The invention is further illustrated by the following examples:
example 1
Measuring 5mL of tetrabutyl titanate, slowly dropwise adding the tetrabutyl titanate into 5mL of absolute ethyl alcohol under magnetic stirring to obtain a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dropwise adding the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 2, and stopping dropwise adding to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
1.89g of zirconyl nitrate is weighed and dissolved in 10mL of deionized water, ultrasonic dispersion is carried out for 5min to obtain a clear zirconyl nitrate solution, 0.2g of gadolinium nitrate nonahydrate is weighed and dissolved in the zirconyl nitrate solution, ultrasonic dispersion is carried out for 5min to obtain a clear Zr-Gd mixed solution, and the mixed solution is dripped to 10g of TiO by an isovolumetric impregnation method 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h on the surface of the-C carrier to obtain Zr-Gd/TiO 2 -C catalyst, wherein ZrO 2 The loading is 1%, gd 2 O 3 The loading was 1%.
3.0mL of Zr-Gd/TiO was weighed 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion was 92%, the isobutene selectivity was 73% and the isoprene yield was 45%.
Example 2
Measuring 5mL of tetrabutyl titanate, slowly dripping the tetrabutyl titanate into 7.5mL of absolute ethyl alcohol under magnetic stirring to obtain a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dripping the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 4, and stopping dripping to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
1.89g of zirconyl nitrate is weighed and dissolved in 10mL of deionized water, ultrasonic dispersion is carried out for 5min to obtain a clear zirconyl nitrate solution, 0.2g of gadolinium nitrate nonahydrate is weighed and dissolved in the zirconyl nitrate solution, ultrasonic dispersion is carried out for 5min to obtain a clear Zr-Gd mixed solution, and the mixed solution is dripped to 10g of TiO by an isovolumetric impregnation method 2 -SiO 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Zr-Gd/TiO 2 -SiO 2 Catalyst, wherein ZrO 2 The loading is 1%, gd 2 O 3 The loading was 1%.
3.0mL of Zr-Gd/TiO was weighed 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, and isobutene is fed inThe material rate was 50mL/min, the nitrogen flow rate was 20mL/min, and the reaction temperature was 300 ℃. The formaldehyde conversion was 95%, the isobutene selectivity was 76% and the isoprene yield was 50%.
Example 3
Measuring 5mL of tetrabutyl titanate, slowly dripping the tetrabutyl titanate into 7.5mL of absolute ethyl alcohol under magnetic stirring to obtain a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dripping the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 4, and stopping dripping to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
0.3g of palladium chloride is weighed and dissolved in 10mL of deionized water, ultrasonic dispersion is carried out for 5min to obtain a clear palladium chloride solution, 0.2g of gadolinium nitrate nonahydrate is weighed and dissolved in the palladium chloride solution, ultrasonic dispersion is carried out for 5min to obtain a clear Pd-Gd mixed solution, and the mixed solution is dripped to 10g of TiO by an isovolumetric impregnation method 2 -SiO 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Pd-Gd/TiO 2 -SiO 2 Catalyst, wherein the PdO loading is 1.2%, gd 2 O 3 The loading was 1%.
3.0mL Pd-Gd/TiO was weighed 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion was 85%, the isobutene selectivity was 70% and the isoprene yield was 36%.
Example 4
5mL of tetrabutyl titanate was measured and slowly added dropwise to 10mL under magnetic stirringAnd (3) in absolute ethyl alcohol, obtaining a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dripping the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 4, and stopping dripping to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
0.3g of palladium chloride is weighed and dissolved in 10mL of deionized water, ultrasonic dispersion is carried out for 5min to obtain a clear palladium chloride solution, 0.3g of ammonium cerium nitrate is weighed and dissolved in the palladium chloride solution, ultrasonic dispersion is carried out for 5min to obtain a clear Pd-Ce mixed solution, and the mixed solution is dripped to 10g of TiO by an isovolumetric impregnation method 2 -SiO 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Pd-Ce/TiO 2 -SiO 2 Catalyst, wherein the PdO loading is 1.2%, ceO 2 The loading was 1%.
3.0mL Pd-Ce/TiO was weighed 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion was 89%, the isobutene selectivity was 77% and the isoprene yield was 40%.
Comparative example 1
Preparing 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, taking 14mL of the solution, and dripping the solution to 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, drying at 120 ℃ for 12h, roasting at 500 ℃ for 5h, and grinding into powder to obtain the acid-treated C carrier.
Weighing 0.3g of palladium chloride, dissolving in 10mL of deionized water, and performing ultrasonic dispersion for 5min to obtainTo clear palladium chloride solution, 0.3g of ammonium ceric nitrate is weighed and dissolved in the palladium chloride solution, ultrasonic dispersion is carried out for 5min, so as to obtain clear Pd-Ce mixed solution, and the mixed solution is dripped to 10g of SiO by an isovolumetric dipping method 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Pd-Ce/SiO 2 Catalyst, wherein the PdO loading is 1.2%, ceO 2 The loading was 1%.
Weigh 3.0mL Pd-Ce/SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion was 80%, the isobutene selectivity was 65% and the isoprene yield was 35%.
Comparative example 2
Measuring 5mL of tetrabutyl titanate, slowly dropwise adding the tetrabutyl titanate into 5mL of absolute ethyl alcohol under magnetic stirring to obtain a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dropwise adding the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 2, and stopping dropwise adding to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
Weighing 0.3g of niobium oxalate and dissolving in 10mL of deionized water, performing ultrasonic dispersion for 5min to obtain a clear niobium oxalate solution, weighing 0.2g of gadolinium nitrate nonahydrate and dissolving in the niobium oxalate solution, performing ultrasonic dispersion for 5min to obtain a clear Nb-Gd mixed solution, and dripping the mixed solution to 10g of TiO by an isovolumetric impregnation method 2 -SiO 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Nb-Gd/TiO 2 -SiO 2 Catalyst, wherein Nb 2 O 5 Load amount1%, gd 2 O 3 The loading was 1%.
Weigh 3.0mL Nb-Gd/TiO 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere of 50mL/min at 300 ℃ before the reaction, so as to remove impurities remained in the system and ensure that reactants and products can smoothly pass through the reaction system during the reaction. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion obtained was 90%, the isobutene selectivity was 70% and the isoprene yield was 43%.
Comparative example 3
Measuring 5mL of tetrabutyl titanate, slowly dripping the tetrabutyl titanate into 7.5mL of absolute ethyl alcohol under magnetic stirring to obtain a uniform pale yellow tetrabutyl titanate solution, preparing a 0.01mol/L glacial acetic acid-absolute ethyl alcohol mixed solution, wherein absolute ethyl alcohol is used as a solvent, glacial acetic acid is used as a solute, slowly dripping the solution into the tetrabutyl titanate solution under stirring until the PH of the solution is 4, and stopping dripping to obtain the acidic tetrabutyl titanate solution. Dripping 10g of clean nano-grade SiO by adopting an isovolumetric dipping method 2 Standing at room temperature for 24h, oven drying at 120deg.C for 12h, roasting at 500deg.C for 5h, grinding into powder to obtain TiO 2 -SiO 2 A carrier, wherein TiO 2 The loading was 20%.
Weighing 0.3g of niobium oxalate and dissolving in 10mL of deionized water, performing ultrasonic dispersion for 5min to obtain a clear niobium oxalate solution, weighing 0.2g of gadolinium nitrate nonahydrate and dissolving in the niobium oxalate solution, performing ultrasonic dispersion for 5min to obtain a clear Nb-Gd mixed solution, and dripping the mixed solution to 10g of TiO by an isovolumetric impregnation method 2 -SiO 2 Standing at normal temperature for 24h, drying at 120 ℃ for 12h, and roasting at 500 ℃ for 5h to obtain Nb-Gd/TiO 2 -SiO 2 Catalyst, wherein Nb 2 O 5 The loading amount is 1.2%, gd 2 O 3 The loading was 1%.
Weigh 3.0mL Nb-Gd/TiO 2 -SiO 2 The catalyst is filled into a fixed bed reactor, and is treated for 3 hours in a nitrogen atmosphere with the temperature of 300 ℃ and the concentration of 50mL/min before the reaction, and the retention in the system is removed during the reactionAnd ensures that reactants and products can pass smoothly through the reaction system. During the reaction, the feeding rate of formaldehyde is 0.05mL/min, the feeding rate of isobutene is 50mL/min, the flow rate of nitrogen is 20mL/min, and the reaction temperature is 300 ℃. The formaldehyde conversion was 92%, the isobutene selectivity was 72% and the isoprene yield was 45%.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (10)

1. A catalyst characterized in that it comprises a support and a first transition metal oxide, a second transition metal oxide and a rare earth metal oxide supported on the support;
the first transition metal and the second transition metal are not the same;
the first transition metal oxide is TiO 2 。
2. The catalyst of claim 1, wherein the loading of the first transition metal is from 5% to 50%;
the loading amount of the second transition metal oxide is 0.1% -10%;
the loading of the rare earth metal oxide is 0.1% -10%.
3. The catalyst of claim 2, wherein the loading of the first transition metal is from 10% to 20%;
the loading capacity of the second transition metal oxide is 1% -2%;
the loading of the rare earth metal oxide is 1% -2%.
4. The catalyst of claim 1, wherein the second transition metal is selected from Pd, zr, cs, mo, V, cu, zn, cr, fe, co or Ni.
5. The catalyst of claim 1, wherein the rare earth metal is selected from La, ce, rb, pr, gd, er, tm, sm, tb or Ho.
6. The catalyst of claim 1, wherein the support is selected from the group consisting of SiO 2 、γ-Al 2 O 3 MgO, caO, mnO or BaO.
7. A method for preparing the catalyst according to any one of claims 1 to 6, comprising the steps of:
step 1) mixing a titanium source solution and a carrier, and performing first calcination;
step 2) mixing a second transition metal source, a rare earth metal source and the product obtained in the step 1), and performing second calcination to obtain the catalyst.
8. The method according to claim 7, wherein the pH of the titanium source solution is 1 to 6.
9. The synthesis method of isoprene is characterized by comprising the following steps:
reacting formaldehyde with isobutene under the action of a catalyst to obtain isoprene;
the catalyst is the catalyst according to any one of claims 1 to 6.
10. The synthesis method according to claim 9, wherein the formaldehyde, the isobutene and the catalyst are used in an amount of (0.05 to 0.5): (50-150): (0.5-5).
CN202310399586.2A 2023-04-14 2023-04-14 Catalyst, preparation method thereof and isoprene synthesis method Pending CN116371396A (en)

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