CN114054100B - Preparation and application of doped composite oxide catalyst - Google Patents

Preparation and application of doped composite oxide catalyst Download PDF

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CN114054100B
CN114054100B CN202010785589.6A CN202010785589A CN114054100B CN 114054100 B CN114054100 B CN 114054100B CN 202010785589 A CN202010785589 A CN 202010785589A CN 114054100 B CN114054100 B CN 114054100B
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ionic liquid
catalyst
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doped composite
metal salt
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CN114054100A (en
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闫瑞一
李梦悦
吕兆坡
马冬菊
李春山
张锁江
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Institute of Process Engineering of CAS
Langfang Institute of Process Engineering of CAS
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Langfang Institute of Process Engineering of CAS
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0278Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
    • B01J31/0281Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
    • B01J31/0284Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aromatic ring, e.g. pyridinium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/26Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
    • B01J31/34Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24 of chromium, molybdenum or tungsten
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/26Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
    • B01J31/36Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24 of vanadium, niobium or tantalum
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/21Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
    • C07C51/215Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of saturated hydrocarbyl groups
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2231/00Catalytic reactions performed with catalysts classified in B01J31/00
    • B01J2231/70Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues

Abstract

The invention relates to a method for synthesizing a doped composite metal oxide catalyst for producing methacrolein from isobutene/tertiary butanol in ionic liquid. The ionic liquid used in the invention is imidazole ionic liquid. And (2) fully and uniformly mixing a certain amount of metal salt solution, introducing a doping body into the slurry, performing an ionic heat strengthening process to obtain catalyst precursor slurry, drying and roasting the slurry prepared in the step under a certain condition to obtain the ionic heat-assisted synthesized doped composite metal oxide catalyst. According to the invention, the imidazole ionic liquid is effectively introduced into the catalyst preparation process, so that the catalyst has a regular microstructure, has the advantages of high temperature resistance and catalytic activity, further improves the mesostructure of the composite metal oxide by doping, and improves the reaction selectivity under the condition of keeping higher conversion rate in the process of producing methacrolein by selective oxidation of isobutylene/tert-butyl alcohol, thereby reducing the cost and being suitable for industrial application.

Description

Preparation and application of doped composite oxide catalyst
Technical Field
The invention relates to a preparation method of an imidazole ionic liquid assisted synthesis doped composite oxide catalyst, which is applicable to the reaction of producing methacrolein from isobutene/tert-butyl alcohol and belongs to the field of preparation and application of catalysts for producing acrylate chemicals.
Background
Methacrylic acid (MAA) and Methyl Methacrylate (MMA) are important organic chemical raw materials and industrial intermediates, and are mainly used for producing polymerization products such as organic glass, light guide plates, light guide fibers and the like.
At present, the clean production process taking the petrochemical industry and coal chemical industry byproduct C4 as raw materials has the key point that the high-efficiency catalyst is used for realizing the process for synthesizing the methacrolein by oxidizing the isobutene/tertiary butanol. The existing catalyst mostly adopts a composite oxide system based on Mo-Bi-Co-Fe-O, and the industrial catalyst has lower activity and higher raw material cost. Therefore, the catalyst activity is improved by the composition and preparation process of the multi-side heavy catalyst which is published in the prior art, for example, the CN101385978A introduces tungsten element into Mo-Bi-Co-Fe-O composite oxide to improve the catalyst activity and the thermal stability; patents US5892108, CN1486787A, CN201910205352.3, etc. add alkali metal (K, cs) to Mo-Bi-Fe-O catalyst, thereby increasing selectivity of catalyst to methacrolein. The addition of the auxiliary elements improves the catalyst performance and further increases the catalyst cost. The isobutene selective oxidation reaction has violent heat release, and hot spots are easily formed in the reactor, so that the deep oxidation reaction is initiated to reduce the activity of the catalyst, and the service cycle of the catalyst is shortened. The CN1029228 patent loads the catalyst in a mode that the particle size is from small to large, increases the reaction contact area, and inhibits the occurrence of local overheating areas in a reaction tube, and has the defects of low catalyst activity, large dosage and high cost.
Due to the unique adjustability of the anion and cation structures, the ionic liquid attracts attention in the material synthesis process. The ionic liquid can obtain materials with different properties by effectively regulating and controlling the particle size, morphology and dispersity of the product. According to the invention, the imidazole ionic liquid is utilized to realize the orientation of a specific crystal form microstructure, so that the catalyst has the advantages of high stability and high temperature resistance of the imidazole ionic liquid and catalytic activity, the high efficiency of the catalyst is enhanced, the catalytic economy is improved, the mesostructure of the composite metal oxide is improved by doping, the performance of the catalyst is improved, and the industrial production cost is reduced.
Disclosure of Invention
The invention provides a method for auxiliary synthesis of doped composite metal oxide in a system containing imidazole ionic liquid, compared with the prior art, the method has the advantages of simple process and raw material cost saving, and can promote the dopant to be uniformly distributed in the catalyst through the ionic liquid. The method comprises the steps of adding a certain amount of doping bodies in the preparation pulping stage, uniformly mixing and doping metal salts and the doping bodies under the auxiliary action of ionic liquid (under the condition of ionic heat endogenous high pressure), and then roasting, activating and forming to obtain the high-activity doped composite oxide catalyst. The catalyst is used for the reaction of synthesizing methacrolein by isobutene/tertiary butanol gas phase oxidation, and shows excellent catalytic activity.
The chemical expression of the doped metal oxide catalyst is as follows: mo 12 Bi a Fe b Co c X d Y e O m The doping material is selected from SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve.
The preparation process of the catalyst comprises the following steps: fully and uniformly mixing a certain amount of aqueous solution of molybdenum-containing metal salt, then mixing and reacting coprecipitator containing metal salt under a certain condition, aging and pulping, adding a doping material into the pulp to prepare under the condition of ionic thermal crystallization, drying, roasting and molding under a certain condition after crystallization, and finally obtaining the doping type composite oxide catalyst.
The doping body in the working procedure is preferably SBA-15 molecular sieve; the mass ratio of the dopant to the metal salt is 0.01 to 1;
the filling rate of the metal salt precursor slurry in the hydrothermal kettle is 80%, the ionic thermal crystallization temperature is 100-200 ℃, and the hydrothermal time is 8-24h.
The drying mode in the working procedure can be one of evaporation drying, vacuum drying or reduced pressure rotary evaporation drying; the baking temperature is 350 to 650 ℃, the heating rate is 1 to 10 ℃/min, preferably 3~6 ℃/min, and the baking time is 2 to 24h, preferably 4 to 10h.
The supported composite metal oxide catalyst prepared by the invention is used for catalyzing isobutene gas phase oxidation in a gas phase to synthesize methacrolein through molecular oxygen in air in a fixed bed.
The isobutene conversion was calculated as follows:
x (isobutylene)% = [1- (amount of unreacted isobutylene substance/amount of supplied isobutylene substance) ] × 100%
The selectivity of methacrolein is calculated as follows:
s (methacrolein)% = [ amount of substance of methacrolein produced/(amount of substance of isobutylene supplied-amount of substance of unreacted isobutylene) ] × 100%
In the preparation process of the catalyst, the adjustability of the positive and negative structures of the ionic liquid is utilized, the microscopic size and the morphology of the catalyst are regulated and controlled, meanwhile, the adulterant and the active component are promoted to be fused to form the doped catalyst, and the doped high-efficiency catalyst is obtained through the further drying and roasting process. In the process of preparing the methylpropionaldehyde by selectively oxidizing gas-phase isobutene by using the catalyst, the highest isobutene conversion rate can reach 98.5 percent, and the highest MAL selectivity can reach 89.7 percent. The doped catalyst provided by the invention is simple in preparation process, low in cost and beneficial to industrial application.
Drawings
Fig. 1 is an SEM image of the use of imidazole-based ionic liquids to assist in the synthesis of doped catalysts.
Detailed Description
The present invention is illustrated below by way of examples, but the scope of the present invention is not limited by the examples.
Example 1
Measuring 30mL of deionized water, adding 7.00g of ammonium molybdate, and dissolving at 50 ℃;0.5wt% BmimBF 4 Dissolving the ionic liquid in 35mL of deionized water, fully stirring and mixing the solutionObtaining a material A through solution; then taking 7.71g of cobalt nitrate, 2.52g of bismuth nitrate, 1.33g of ferric nitrate, 0.57g of cesium nitrate, 0.26g of cerium nitrate and 0.07g potassium nitrate, and stirring and dissolving in 15mL of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 1wt% of SBA-15 into the material B, and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, wherein the filling rate is 80%, and reacting at 100 ℃ for 10 hours to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 360 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 2
Measuring 20mL of deionized water, adding 4.73g of ammonium molybdate, and dissolving at 50 ℃;0.2wt% of C 8 mimBF 4 Dissolving the ionic liquid in 45mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then taking 5.13g of cobalt nitrate, 1.67g of bismuth nitrate, 0.89g of ferric nitrate, 0.41g of cesium nitrate, 0.23g of cerium nitrate and 0.06g of copper nitrate, and stirring and dissolving in 15mL of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 0.1wt% of SBA-15 into the material B and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and reacting for 10 hours at 120 ℃ to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide is catalyzedThe catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the catalyst is prepared by mixing isobutene: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 360 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out using n-heptanol to absorb the mixed gas, and the evaluation results are shown in Table 1.
Example 3
Measuring 50mL of deionized water, adding 11.67g of ammonium molybdate, and dissolving at 50 ℃;0.1wt% of C 10 mimBF 4 Dissolving the ionic liquid in 15mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then taking 12.81g of cobalt nitrate, 4.27g of bismuth nitrate, 2.22g of ferric nitrate, 0.95g of cesium nitrate, 0.43g of cerium nitrate, 0.17g of potassium nitrate and 0.29g of zinc oxide, and stirring and dissolving in 15mL of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 2wt% of SBA-15 into the material B, and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacting at 100 ℃ for 10h to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as the raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 4
Measuring 30mL of deionized water, adding 7.00g of ammonium molybdate, and dissolving at 50 ℃;0.5wt% of C 12 mimBF 4 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then 7.71g of cobalt nitrate, 2.52g of bismuth nitrate, 1.33g of ferric nitrate, 0.57g of cesium nitrate, 0.26g of cerium nitrate, 0.07g of potassium nitrate and 0.05g of nitric acidLanthanum is dissolved in 15ml of nitric acid solution with the mass fraction of 5 percent at the temperature of 50 ℃ by stirring to obtain a material B; adding 0.5wt% of SBA-15 into the material B and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacting at 150 ℃ for 10 hours to obtain the required catalyst precursor.
And (3) placing the obtained catalyst precursor in a drying oven at 100 ℃ for drying, and placing the obtained solid in air flow at 450 ℃ for roasting for 3 hours to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol to absorb the mixed gas, and the evaluation results are shown in Table 1.
Example 5
Measuring 20mL of deionized water, adding 4.73g of ammonium molybdate, and dissolving at 50 ℃;0.2wt% of C 14 mimBF 4 Dissolving the ionic liquid in 45mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then 5.13g of cobalt nitrate, 1.67g of bismuth nitrate, 0.89g of ferric nitrate, 0.38g of cesium nitrate, 0.17g of cerium nitrate, 0.035 g potassium nitrate and 0.026 g nickel nitrate are taken, stirred and dissolved in 15ml of nitric acid solution with the mass fraction of 5% at the temperature of 50 ℃ to obtain a material B; adding 1wt% of gMCM-41 into the material B, and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and reacting for 10 hours at 100 ℃ to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen gas: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 6
Measuring 50mL of deionized water, adding 11.67g of ammonium molybdate, and dissolving at 50 ℃;0.5wt% of C 8 mimBF 4 Dissolving the ionic liquid in 15mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then taking 12.81g of cobalt nitrate, 4.27g of bismuth nitrate, 2.22g of ferric nitrate, 0.95g of cesium nitrate, 0.43g of cerium nitrate, 0.17g of potassium nitrate and 0.15g of zirconium nitrate, and stirring and dissolving the mixture in 15ml of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 2wt% of MCM-41 into the material B, and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacting at 100 ℃ for 10h to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 7
Measuring 20mL of deionized water, adding 4.73g of ammonium molybdate, and dissolving at 50 ℃;1wt% of C 10 mimBF 4 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then 5.13g of cobalt nitrate, 1.67g of bismuth nitrate, 0.89g of ferric nitrate, 0.38g of cesium nitrate, 0.17g of cerium nitrate, 0.07g potassium nitrate and 0.04 g copper nitrate are taken, stirred and dissolved in 15ml of nitric acid solution with the mass fraction of 5% at the temperature of 50 ℃ to obtain a material B; adding 0.5wt% MCM-41 into material B and stirring to obtain a mixtureMaterial preparation; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacting at 100 ℃ for 10 hours to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 360 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 8
Measuring 30mL of deionized water, and adding 7g of ammonium molybdate to dissolve at 50 ℃;5wt% of C 12 mimBF 4 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then, 7.7g of cobalt nitrate, 2.5g of bismuth nitrate, 1.33g of ferric nitrate, 0.57g of cesium nitrate, 0.26g of cerium nitrate, 0.07g potassium nitrate and 0.054 g neodymium nitrate are taken, and stirred and dissolved in a nitric acid solution with the mass fraction of 5% of 15ml at the temperature of 50 ℃ to obtain a material B; adding 0.1wt% of MCM-41 into the material B and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, wherein the filling rate is 80%, and reacting at 100 ℃ for 10 hours to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 Reacting at 340 ℃ under normal pressure,after 1 hour of the reaction, the mixed gas was absorbed by n-heptanol and analyzed by gas chromatography, and the evaluation results are shown in Table 1.
Example 9
Measuring 30mL of deionized water, adding 7g of ammonium molybdate, and dissolving at 50 ℃; 0.5wt.% of 14 mimBF 4 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then, taking 7.7g of cobalt nitrate, 2.5g of bismuth nitrate, 1.33g of ferric nitrate, 0.57g of cesium nitrate, 0.26g of cerium nitrate, 0.07g of potassium nitrate and 0.049g of antimony nitrate, and stirring and dissolving the cobalt nitrate, the bismuth nitrate, the ferric nitrate, the cesium nitrate, the cerium nitrate, the potassium nitrate and the antimony nitrate in 15ml of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 0.5wt% of KIT-6 into the material B and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and reacting for 10 hours at 150 ℃ to obtain the required catalyst precursor.
And (3) placing the obtained catalyst precursor in a drying oven at 100 ℃ for drying, and placing the obtained solid in air flow at 450 ℃ for roasting for 3 hours to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled in the upper part and the lower part of the catalyst, and the ratio of isobutene: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol to absorb the mixed gas, and the evaluation results are shown in Table 1.
Example 10
Measuring 50mL of deionized water, adding 11.67g of ammonium molybdate, and dissolving at 50 ℃;0.5wt% BmimNO 3 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then taking 12.81g of cobalt nitrate, 4.27g of bismuth nitrate, 2.22g of ferric nitrate, 0.95g of cesium nitrate, 0.43g of cerium nitrate and 0.006g of niobium nitrate, and stirring and dissolving in 15ml of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 2wt% of KIT-6 into the material B, and stirring to obtain a mixed material; then slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacting at 150 ℃ for 10h to obtain the polytetrafluoroethylene-lined high-pressure reaction kettleThe desired catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled in the upper part and the lower part of the catalyst, and the ratio of isobutene: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 350 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 11
Measuring 30mL of deionized water, adding 7.00g of ammonium molybdate, and dissolving at 50 ℃;1wt% of BmimNO 3 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then, 7.70g of cobalt nitrate, 2.5g of bismuth nitrate, 1.33g of ferric nitrate, 0.57g of cesium nitrate, 0.26g of cerium nitrate and 0.054 g ammonium metavanadate are taken, stirred and dissolved in a nitric acid solution with the mass fraction of 15ml at 50 ℃ to obtain a material B; adding 1wt% of KIT-6 into the material B, and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, wherein the filling rate is 80%, and reacting at 100 ℃ for 10 hours to obtain the required catalyst precursor.
And (3) drying the obtained catalyst precursor in a drying box at 100 ℃, and roasting the obtained solid in air flow at 450 ℃ for 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol as an absorption mixed gas, and the evaluation results are shown in Table 1.
Example 12
Measuring 20mL of deionized water, adding 4.73g of ammonium molybdate, and dissolving at 50 ℃;2wt% of BmimNO 3 Dissolving the ionic liquid in 35mL of deionized water, and fully stirring, mixing and dissolving to obtain a material A; then 5.13g of cobalt nitrate, 1.67g of bismuth nitrate, 0.89g of ferric nitrate, 0.38g of cesium nitrate, 0.17g of cerium nitrate and 0.043 g of silver nitrate are taken, stirred and dissolved in 15ml of nitric acid solution with the mass fraction of 5% at 50 ℃ to obtain a material B; adding 0.5wt% of KIT-6 into the material B and stirring to obtain a mixed material; and slowly dropwise adding the material B into the material A to form slurry, transferring the obtained slurry into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and reacting for 10 hours at 100 ℃ to obtain the required catalyst precursor.
And placing the obtained catalyst precursor in a drying box at 100 ℃ for drying, placing the obtained solid in air flow at 450 ℃ for roasting 3h to obtain the doped composite metal oxide catalyst.
The obtained doped composite metal oxide catalyst is filled in a fixed bed reactor with the inner diameter of 20mm, quartz sand with equal grain diameter is filled above and below the catalyst, and the ratio of isobutene to the mixed metal oxide is as follows: oxygen: the mixed gas of nitrogen =1: 1.7: 12 (molar ratio) is used as raw material, and the space velocity is 2000h -1 The reaction was carried out at 340 ℃ under normal pressure, and after 1 hour of the reaction, the gas chromatography analysis was carried out by using n-heptanol to absorb the mixed gas, and the evaluation results are shown in Table 1.
Comparative example 1
Compared with the example 1, the preparation process of the catalyst does not add BmimBF 4 And SBA-15, the other conditions were exactly the same as in example 1, and the evaluation results are shown in Table 1.
Comparative example 2
In comparison with example 4, in this comparative example, no SBA-15 was added during the catalyst preparation process, and the other conditions were exactly the same as in example 4, and the evaluation results are shown in Table 1.
Comparative example 3
In this comparative example, KIT-6 was not added during the catalyst preparation process, and the other conditions were exactly the same as in example 10, as compared with example 10, and the evaluation results are shown in Table 1.
Comparative example 4
This comparative example compares to example 6, catalyst preparation procedureIn which C is not added 8 mimBF 4 Otherwise, the conditions were exactly the same as in example 6, and the evaluation results are shown in Table 1.
Comparative example 5
In comparison with example 12, this comparative example shows that no BmimNO was added during the catalyst preparation 3 Otherwise, the conditions were exactly the same as in example 12, and the evaluation results are shown in Table 1.
Table 1 catalyst test evaluation results
Catalyst composition Reaction temperature (. Degree.C.) Conversion of isobutene (%) MAL Selectivity (%)
Example 1 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 O h / 0.5wt%BmimBF 4 +1wt% SBA-15 360 97.2 89.5
Example 2 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Cu 0.4 O h / 0.2wt%C 8 mimBF 4 +0.1wt% SBA-15 360 97.6 85.9
Example 3 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 Zn 0.4 O h / 0.1wt%C 10 mimBF 4 +2wt% SBA-15 340 98.5 87.2
Example 4 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 La 0.4 O h / 0.5wt%C 12 mimBF 4 +0.5wt% SBA-15 340 97.9 88.2
Example 5 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 Ni 0.4 O h / 0.2wt%C 14 mimBF 4 +1wt% MCM-41 340 98.1 89.3
Example 6 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.2 Ce 0.2 K 0.2 Zr 0.2 O h / 0.5wt%C 8 mimBF 4 +2wt% MCM-41 340 96.5 84.5
Example 7 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.2 Ce 0.2 K 0.2 Cu 0.2 O h / 1wt%C 10 mimBF 4 +0.5wt% MCM-41 360 94.5 87.9
Example 8 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.2 Ce 0.2 K 0.2 Nd 0.2 O h / 5wt%C 12 mimBF 4 +0.1wt%MCM-41 340 97.9 88.9
Example 9 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Nb 0.4 O h / 0.5wt%BmimNO 3 +2wt% KIT-6 340 97.2 89.7
Example 10 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Nb 0.4 O h / 0.5wt%BmimNO 3 +2wt% KIT-6 350 97.6 88.4
Example 11 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 V 0.4 O h / 1wt%BmimNO 3 +1wt% KIT-6 340 96.7 85.2
Example 12 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Ag 0.4 O h / 2wt%BmimNO 3 +0.5wt% KIT-6 340 93.8 80.1
Comparative example 1 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 O h 360 69.8 61.1
Comparative example 2 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 K 0.4 La 0.4 O h / 0.5wt%C 12 mimBF 4 340 70.4 76.9
Comparative example 3 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Nb 0.4 O h / 0.5wt%BmimNO 3 350 70.8 77.3
Comparative example 4 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.2 Ce 0.2 K 0.2 Zr 0.2 O h /2wt% MCM-41 340 82.7 78.9
Comparative example 5 Mo 12 Bi 1.6 Co 8 Fe 1 Cs 0.4 Ce 0.4 Ag 0.4 O h / 0.5wt% KIT-6 340 82.3 78.5
As can be seen from the table above, when the catalyst provided by the invention is applied to the process of producing methacrolein from isobutene/tert-butanol, the highest isobutene conversion rate can reach 98.5%, and the highest MAL selectivity can reach 89.7%.
It can be seen by comparing examples 1, 5, 11 with comparative example 1. When the catalyst contains the ionic liquid and the doping body at the same time, the catalytic activity is higher.
Comparing examples 4, 8 and 12 with comparative examples 2 and 3, it can be seen that the ionic liquid-assisted synthesis catalyst has higher selectivity to methacrolein, and mainly the organic ligand of the imidazole ionic liquid enters the catalyst, so that the catalyst has the advantages of high stability and temperature resistance of the ionic liquid, and the high-temperature deactivation rate of the catalyst is reduced.
It can be seen by comparing examples 6 and 12 with comparative examples 4 and 5 that the doped catalyst still maintains a high catalytic activity.

Claims (6)

1. The method for synthesizing the doped composite oxide with the assistance of the imidazole ionic liquid is characterized in that the imidazole ionic liquid assists the crystallization process and comprises the following steps:
(1) Preparing metal salt precursor slurry:
uniformly mixing a quantitative doping body and a Mo-containing metal salt solution to obtain a solution A, dropwise adding a metal salt precipitator aqueous solution prepared according to a stoichiometric ratio into the solution A, and mixing to obtain a slurry, adding an imidazole ionic liquid into the slurry, and fully stirring and mixing to obtain a metal salt precursor slurry; the doping body is one or a mixture of more than two of SBA type molecular sieve, MCM type molecular sieve, FDU type molecular sieve, KIT type molecular sieve and MSU type molecular sieve; the Mo-containing solution is selected from water-soluble compounds of metal Mo; the metal salt-containing precipitator is one or more selected from Co, bi, fe, cu, mg, ni, V, ti, zn, K, cs, la, ce, nd, zr, nb, sb, sr and Ag; the imidazole ionic liquid comprises BmimBF 4 、C 8 mimBF 4 、C 10 mimBF 4 、C 12 mimBF 4 、C 14 mimBF 4 、C 16 mimBF 4 、EmimNO 3 、BmimNO 3 、EmimCl、BmimCl;
(2) Ionic thermal crystallization reaction:
transferring the metal salt precursor slurry into a reaction kettle, and carrying out ionic thermal crystallization reaction for a certain time in the presence of ionic liquid to obtain the slurry, wherein the filling rate of the metal salt slurry in the hydrothermal kettle is 80%, the ionic thermal crystallization temperature is higher than 100 ℃, and the hydrothermal time is more than 8 h;
(3) And (3) roasting and forming:
and drying and roasting the slurry under certain conditions to obtain the doped composite oxide catalyst.
2. The method for synthesizing the doped composite oxide with the assistance of the imidazole ionic liquid according to claim 1, wherein the amount of the ionic liquid accounts for 0.1 to 5wt% of the mass fraction of the metal salt precursor slurry.
3. The method for synthesizing the doped composite oxide assisted by the imidazole ionic liquid according to claim 1, wherein the doped materials are selected from one or a mixture of more than two of SBA-1, SBA-2, SBA-3, SBA-8, SBA-12, SBA-15 molecular sieves, MCM-41, MCM-48 molecular sieves, FDU-1, FDU-5 molecular sieves, KIT-6 and MSU type molecular sieves in any proportion.
4. The method for synthesizing the doped composite oxide under the assistance of the imidazole ionic liquid according to claim 1, wherein the added dopant accounts for 0.1 to 10wt% of the total weight of the molded catalyst.
5. The method for synthesizing the doped composite oxide with the assistance of the imidazole ionic liquid according to claim 1, wherein the filling rate of the metal salt slurry in a hydrothermal kettle is 80%, the ionic thermal crystallization temperature is 100 to 200 ℃, and the hydrothermal time is 8 to 24h.
6. The method for synthesizing the doped composite oxide with the assistance of the imidazole ionic liquid according to claim 1, wherein the drying mode in the process is one selected from evaporation drying, vacuum drying and suction filtration drying; the baking temperature is 350 to 650 ℃, the heating rate is 1 to 10 ℃/min, and the baking time is 2 to 24h.
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