CN110981697B - Method for synthesizing 3-methyl-3-butene-1-ol - Google Patents

Method for synthesizing 3-methyl-3-butene-1-ol Download PDF

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CN110981697B
CN110981697B CN201911311345.8A CN201911311345A CN110981697B CN 110981697 B CN110981697 B CN 110981697B CN 201911311345 A CN201911311345 A CN 201911311345A CN 110981697 B CN110981697 B CN 110981697B
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oxide
catalyst
methyl
dimethyldioxane
isobutene
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CN110981697A (en
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庞计昌
刘英俊
张红涛
朱小瑞
王文
李文滨
汪攀登
张永振
黎源
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Wanhua Chemical Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/36—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring increasing the number of carbon atoms by reactions with formation of hydroxy groups, which may occur via intermediates being derivatives of hydroxy, e.g. O-metal
    • 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
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • 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
    • B01J23/14—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of germanium, tin or lead
    • 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
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/32—Manganese, technetium or rhenium
    • B01J23/34—Manganese
    • 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
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/78—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali- or alkaline earth metals
    • 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
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/80—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with zinc, cadmium or mercury
    • B01J35/50—
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Abstract

The invention provides a method for synthesizing 3-methyl-3-butene-1-ol. The invention takes isobutene and dimethyl dioxane as raw materials, and the raw materials react in a fixed bed filled with a catalyst to obtain 3-methyl-3-butylene-1-alcohol, wherein the conversion rate of the dimethyl dioxane reaches more than 99 percent, and the selectivity reaches more than 98 percent. The method takes the dimethyl dioxane as the raw material to synthesize the 3-methyl-3-butene-1-ol, reduces the production cost and the energy consumption, greatly reduces the discharge amount of three wastes, simplifies the separation process, has stronger continuous operability and is very suitable for amplification and industrialization.

Description

Method for synthesizing 3-methyl-3-butene-1-ol
Technical Field
The invention relates to a method for synthesizing a raw material 3-methyl-3-butylene-1-alcohol of a polycarboxylic acid high-efficiency water reducing agent, belonging to the technical field of organic chemical synthesis.
Background
3-methyl-3-butylene-1-alcohol is an initiator for synthesizing the side chain TPEG polyether of the polycarboxylic acid high-efficiency water reducing agent, and plays a decisive role in the quality and performance of the polycarboxylic acid high-efficiency water reducing agent. In addition, 3-methyl-3-butylene-1-alcohol can also be used for synthesizing methyl carpicidate which is an intermediate of a pyrethroid pesticide with high efficiency and low toxicity, and is also a main raw material for artificially synthesizing citral, and further synthesizing menthol and derivatives thereof, ionone, carotenoid and vitamin A, essences and fragrances, medical supplies and the like. Therefore, the research on synthesizing the 3-methyl-3-butene-1-ol has wide prospect and great economic and social benefits.
The synthetic route is mainly divided into three major categories according to the difference of raw materials for synthesizing 3-methyl-3-buten-1-ol, wherein the first category is an isoprene method, the second category is a methylbutenol isomerization method, and the third category is a Prins method, also called an isobutene method.
Patent 105541544a discloses a method for synthesizing chloroisopentene by using isoprene and hydrogen chloride for catalysis, hydrolyzing to obtain methylbutenol and isopentenol, and then isomerizing to obtain 3-methyl-3-buten-1-ol.
Patent 103787834B discloses a method for producing 3-methyl-3-buten-1-ol by performing deprotection reaction on an intermediate 1 obtained by reacting acetone and formaldehyde with isobutylene under the action of an acid catalyst to obtain 4-hydroxy-2-butanone, and a method for producing 3-methyl-3-buten-1-ol by reacting the intermediate 1 with a methyleneating reagent.
Patent CN102557876A discloses a method for preparing 3-methyl-3-butene-1-ol by Prins condensation by using paraformaldehyde and isobutene as raw materials, chloroform as a solvent and 1.25mol of SnCl4 immobilized on a molecular sieve per gram as a catalyst.
Patent CN105439823A discloses a method for producing 3-methyl-3-butene-1-ol by heating a formaldehyde methanol solution as a raw material to a supercritical state, then feeding the heated formaldehyde methanol solution into a reactor in a spray form, and condensing isobutene, wherein the conversion rate of isobutene is 99% and the selectivity of 3-methyl-3-butene-1-ol is 96% under the conditions that the reaction pressure is 15-22 MPa and the reaction temperature is 220-300 ℃.
Patent CN104130107A discloses a method for synthesizing 3-methyl-3-butene-1-ol by using formaldehyde hemiacetal as a raw material, which synthesizes an aldol condensation compound by using alcohol with 1-5 carbon atoms and formaldehyde, and the aldol condensation compound reacts under the conditions of reaction pressure of 12-18 MPa and reaction temperature of 280-350 ℃, wherein the method not only needs very high temperature and pressure, but also generates alcohol with 1-5 carbon atoms in the synthesis process and needs separation.
In a word, the Prins method in the prior art can efficiently prepare the 3-methyl-3-buten-1-ol, but the raw materials mostly adopt formaldehyde or paraformaldehyde, which has the advantages of low formaldehyde conversion rate and difficulty in separating and removing the formaldehyde, so that the formaldehyde can be remained in the product, the product quality is reduced, and the downstream application of the 3-methyl-3-buten-1-ol is influenced.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the preparation method of the 3-methyl-3-butene-1-ol, which has the advantages of simple process, environmental protection and high yield, and particularly, the 3-methyl-3-butene-1-ol is prepared by the reaction of isobutene and dimethyl dioxane.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method of synthesizing 3-methyl-3-buten-1-ol, the method comprising: in the presence of a catalyst, isobutene and dimethyldioxane are reacted to form 3-methyl-3-buten-1-ol.
Dimethyldioxane as a starting material can be prepared from formaldehyde and isobutylene under the condition of an acidic catalyst; the acidic catalyst can be one or more of sulfuric acid, phosphoric acid, hydrochloric acid, solid acid and heteropoly acid.
In the preparation of dimethyldioxane, the mass ratio of the formaldehyde to the isobutene can be 2:1-8:1.
The reaction temperature in the preparation of dimethyldioxane is preferably 60 to 100 ℃ and the reaction time is preferably 4 to 8 hours.
Preferably, the reaction temperature of isobutylene and dimethyldioxane is 150 to 220 ℃, and further preferably 160 to 200 ℃; the reaction pressure is 4MPa to 15MPa, and more preferably 6MPa to 10MPa.
Preferably, the reaction time of isobutylene and dimethyldioxane is from 10min to 60min, more preferably from 15min to 30min.
Preferably, the molar ratio of isobutene to dimethyldioxane is from 3 to 10:1 to 5, more preferably 5 to 8:2 to 4.
Further, the reaction is carried out under an inert atmosphere such as a nitrogen atmosphere. The reaction is preferably carried out in a fixed bed reactor packed with a catalyst.
The catalyst comprises a main catalyst and an auxiliary catalyst, wherein the main catalyst is a metal oxide, and the auxiliary catalyst is a nitrogen-containing compound. The mass ratio of the main catalyst to the auxiliary catalyst is preferably 6:1 to 3.
The catalyst of the invention can be formed by mixing a main catalyst and a cocatalyst.
Preferably, the procatalyst metal oxide loading is preferably from 3 to 40 wt.%, more preferably from 5 to 20 wt.%, based on the mass of the support; the nitrogen-containing compound loading amount of the cocatalyst is preferably 1 to 15wt%, more preferably 2 to 5wt%.
The main catalyst of the catalyst according to the present invention is preferably a metal oxide including, but not limited to, two or more of magnesium oxide, calcium oxide, manganese oxide, barium oxide, iron oxide, copper oxide, zinc oxide, tin oxide, strontium oxide, such as manganese oxide and barium oxide, calcium oxide and iron oxide, copper oxide and zinc oxide, strontium oxide and magnesium oxide, preferably including at least one alkaline earth metal oxide and at least one oxide selected from iron, copper, tin, manganese, strontium, and the metal oxide is added as the main catalyst, which can effectively promote the cracking of dimethyldioxane, accelerate the reaction with isobutylene, lower the reaction temperature and pressure, reduce the reaction time, and make the reaction conditions milder.
Preferably, the co-catalyst is selected from one or more of the group consisting of imides, carboxamides, fatty amines, aromatic amines, nitrogen-containing heterocycles, quaternary ammonium bases, including but not limited to one or more of phthalimides, propiolactams, caprolactam, dimethylaniline, p-toluidine, methylethylcyclopropylamine, p-chloroaniline, tetradecyldimethylamine, dodecyldimethyl tertiary amine, decaalkyldimethyl tertiary amine, didodecyltriethyl tertiary amine, dioctadecyldecyl tertiary amine, octadecylamine, dioctylamine, didecylamine, dodecylamine, diisooctylamine, isooctylamine, N-pentylamine, N-hexylamine, aminopyridine, pyridine, imidazole, pyrrole, dimethylformamide, triethylamine, N-phenylbenzyamine, tetraisopropylamine iodide, and (2-hydroxyethyl) trimethylamine hydroxide. Adding a nitrogen-containing compound to promote the reaction of the dimethyl dioxane and the isobutene and improve the selectivity of the dimethyl dioxane; on the other hand, the stability of the product 3-methyl-3-butene-1-ol is enhanced, and preferably, the loading of the nitrogen-containing compound can be 1 to 15 weight percent, preferably 2 to 5 weight percent, based on the mass of the carrier.
The carrier of the catalyst according to the present invention, preferably, comprises one or more of alumina, silica and molecular sieve, and has the characteristics of high temperature resistance and high pressure resistance.
The procatalyst may be loaded onto the support using conventional methods. For example, the main catalyst of the present invention can be supported on the carrier by the following method:
firstly, weighing one or more of alumina, silicon oxide and molecular sieve as carriers in a certain mass, adding the two or more of metal oxides in a flask, dissolving the metal oxides by dilute nitric acid, adding the dissolved metal oxides into the flask, placing the mixed solution into an ultrasonic container for mixing, performing ultrasonic treatment on the mixed solution for 1 to 4 hours, standing the mixed solution for 10 hours, adding a weakly alkaline substance, adjusting the pH value of the solution to 10 to completely solidify the solution on the carriers, filtering the solidified solution after 5 hours, washing the solution for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 125 ℃, roasting the dried solid catalyst at 540 ℃ for 4.5 hours, and finally obtaining the composite metal catalyst with uniform particle size and good dispersibility.
The cocatalyst in the present invention can be loaded on the metal oxide-supported catalyst support by the following method:
firstly weighing carrier particles (such as the composite metal catalyst particles prepared above) carrying a main catalyst metal oxide, heating the carrier particles (such as in an oil bath) to 50-100 ℃, weighing a nitrogen-containing compound, adding the nitrogen-containing compound into the heated carrier particles, dissolving and mixing (such as stirring or ultrasound for 1-5 h) by using an organic solvent, then removing the solvent, washing (such as washing by using ethanol), drying (such as drying at 120 ℃) the obtained composite metal catalyst carrying the nitrogen-containing compound, and further roasting (such as roasting at 250 ℃) the obtained composite metal catalyst carrying the nitrogen-containing compound is obtained.
The preparation method of the catalyst comprises the steps of mixing a carrier and a metal oxide in an ultrasonic container, carrying out ultrasonic treatment on a mixed solution for 1-4 hours, standing for 10 hours, adding a weak alkaline substance including but not limited to one or more of ammonia water, ammonium bicarbonate and ammonium carbonate, adjusting the pH of the solution to 10, and enabling the metal oxide to be solidified and completely attached to the carrier. Preferably, the nitrogen-containing compound is blended with the composite metal catalyst particles, the blending organic solvent includes but is not limited to one or more of toluene, xylene, chlorobenzene, dichlorobenzene and ethylbenzene, in a preferred scheme, the blending process of the nitrogen compound and the composite metal catalyst particles is carried out in a nitrogen atmosphere, and in particular, the subsequent process comprises solvent washing and drying.
Preferably, the catalyst is mechanically ground, and a proper amount of polyvinyl alcohol and sesbania powder are added, and then the mixture is dried, roasted, ground, sieved and separated to obtain the solid catalyst with the particle size of 30-100 meshes, preferably 50-80 meshes.
Because the stability of the dimethyl dioxane is higher than that of formaldehyde and formaldehyde hemiacetal, and various structures such as monomers, dimers, polymers and the like do not exist, no formaldehyde is generated in the reaction process, so that the reaction is more stable, and higher conversion rate and selectivity can be obtained by adding a catalyst and adjusting the temperature and the pressure. Because no formaldehyde residue and high polymer are generated in the reaction liquid, formaldehyde does not need to be removed in the subsequent separation treatment process, and because no components such as solvent and the like are generated, the separation process is more efficient, and finally the separation yield of the 3-methyl-3-butene-1-ol is improved.
According to a more specific embodiment of the present invention, a method for synthesizing 3-methyl-3-buten-1-ol comprises:
(1) Firstly, nitrogen or inert gas is used for purging the reactor, and air in the reactor is completely replaced;
(2) Passing isobutylene through a preheater and heating to a desired temperature of 100-300 ℃, preferably 150-220 ℃, and simultaneously passing dimethyldioxane through the preheater to preheat to a desired temperature of 60-140 ℃, more preferably 80-120 ℃;
(3) Mixing the two materials through a mixer, continuously feeding the mixed materials into a fixed bed reactor, and reacting under the action of a catalyst to generate 3-methyl-3-butene-1-ol;
(4) And (3) cooling the reaction liquid, then performing pressure rectification separation, separating unreacted isobutene, introducing the residual reaction liquid into a de-heavy rectifying tower, and extracting the 3-methyl-3-butene-1-ol from a lateral line to obtain the high-purity 3-methyl-3-butene-1-ol.
In the preparation step (3), the reaction pressure is preferably 6MPa to 10MPa, the reaction temperature is preferably 160 ℃ to 200 ℃, and the reaction time is preferably 15min to 30min.
The molar ratio of the isobutylene and dimethyldioxane fed in the above production step (3) is preferably 5 to 8:2 to 4.
Compared with the prior art, the method for preparing the 3-methyl-3-butene-1-ol has the following beneficial effects:
(1) Dimethyl dioxane is used for replacing formaldehyde, reaction raw materials are easy to obtain, byproducts are few, no formaldehyde residue is generated, the problems of low formaldehyde conversion rate and difficulty in separation and removal are solved, and the product quality is improved;
(2) The reaction condition is milder and more reliable, the side reaction is reduced, the preparation is simple, the fixed bed operation is adopted, the continuous production is realized, the production efficiency is improved, and the operation risk is reduced;
(3) The conversion rate of the raw material dimethyl dioxane is more than 99 percent, and the selectivity of isobutene is more than 98 percent.
Detailed Description
In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples. The detection method used in the examples is explained below:
a gas chromatograph is adopted to detect the conversion rate and selectivity of the dimethyl dioxane, and the specific analysis conditions are as follows:
the chromatographic instrument is Agilent 7890A, the model of a chromatographic column is HP-5, the inner diameter is 320.00 mu m, the length is 30.0m, and the highest temperature is 325.0 ℃. And (3) a temperature raising program, namely firstly keeping the temperature at 40 ℃ for 1 minute, raising the temperature to 140 ℃ at 10 ℃/min for 2 minutes, raising the temperature to 280 ℃ at 20 ℃/min for 6 minutes, and keeping the total running time at 30 minutes.
The dimethyldioxanes used in the examples were prepared from formaldehyde and isobutene by the following method: firstly, 500g of Cu-Al-MCM-41 molecular sieve is selected as a catalyst, the catalyst is filled in a reactor, the temperature is raised to 96 ℃ after nitrogen replacement, then an isobutylene replacement reaction system is used, the pressure in the reactor is regulated to 2MPa by controlling a back pressure valve at the outlet of the reactor, isobutylene is preheated to 100 ℃, the feeding speed is 30g/h, a 37% formaldehyde solution is preheated to 95 ℃, the feeding speed is 150g/h, the mixed temperature of the two is 96 ℃, the reaction time is 5.8h, and the dimethyl dioxane with the purity close to 100% can be obtained by simple separation after the reaction liquid is cooled. The conversion rate of isobutene reaches more than 96 percent, and the selectivity of dimethyl dioxane is 100 percent.
Example 1
Preparation of the catalyst
Weighing 500g of molecular sieve, adding into a flask, taking 25g of manganese oxide and 25g of barium oxide, adding dilute nitric acid to dissolve metal oxides, adding into the flask, placing into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 3.5h, standing for 10h, adding ammonia water, adjusting the pH value of the solution to 10, solidifying for 5h, filtering, cleaning for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 125 ℃, and roasting for 4.5h at 540 ℃ to obtain the composite metal catalyst. Weighing 12g of tetradecyl dimethyl tertiary amine, adding toluene to dissolve, mixing 300g of prepared composite metal catalyst, adding into an oil bath, heating to 80 ℃, stirring or ultrasonically treating for 2h, removing the solvent, washing with ethanol, drying at 120 ℃, roasting at 250 ℃ for 3h, and finally processing to obtain the 60-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
1) Adding 200g of the catalyst into a fixed bed, and replacing air in the fixed bed with nitrogen;
2) Preheating isobutene to 190 ℃, introducing the isobutene into a mixer and a fixed bed at a flow of 16g/min, setting the temperature of the fixed bed at 180 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 8MPa, preheating dimethyldioxane to 120 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at a flow rate of 7.5g/min to be mixed with the isobutene, and introducing the mixture into the reactor for reaction for 12 hours continuously;
3) The reaction liquid is cooled and decompressed to 0.5MPa, after isobutene is separated, the reaction liquid is rectified and separated to obtain a product of 3-methyl-3-butene-1-ol, the content of the 3-methyl-3-butene-1-ol is analyzed by gas chromatography, and the yield is calculated to be 97.5%.
Example 2
Preparation of the catalyst
Weighing 500g of alumina, adding the alumina into a flask, taking 30g of calcium oxide and 20g of iron oxide, adding dilute nitric acid to dissolve metal oxides, adding the calcium oxide and the iron oxide into the flask, placing the mixture into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 3.5h, standing the mixed solution for 10h, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, filtering the mixed solution after curing the mixed solution for 4.5h, washing the mixed solution for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 125 ℃, and roasting the solid catalyst at 540 ℃ for 5h to obtain the composite metal catalyst. Weighing 15g of phthalimide, adding toluene to dissolve the phthalimide, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating the mixture to 100 ℃, stirring or ultrasonically treating the mixture for 2 hours, removing the solvent, washing the mixture by using ethanol, drying the mixture at 120 ℃, roasting the mixture for 3.5 hours at 250 ℃, and finally processing the mixture to obtain the 70-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used with the following exceptions: preheating isobutene to 170 ℃, introducing the isobutene into a mixer and a fixed bed at the flow rate of 18g/min, setting the temperature of the fixed bed at 200 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 10MPa, preheating dimethyldioxane to 100 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at the flow rate of 5g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 12 hours continuously, and finally obtaining the yield of the 3-methyl-3-butene-1-ol by calculation, wherein the yield of the 3-methyl-3-butene-1-ol is 97.8 percent.
Example 3
Preparation of the catalyst
Weighing 500g of molecular sieve, adding into a flask, taking 26g of copper oxide and 15g of zinc oxide, adding dilute nitric acid to dissolve metal oxide, adding into the flask, placing into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 3.5h, standing for 10h, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, solidifying for 4.5h, filtering, cleaning for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 125 ℃, and roasting for 5h at 540 ℃ to obtain the composite metal catalyst. Weighing 8.5g of dioctylamine, adding toluene to dissolve, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating to 100 ℃, stirring or ultrasonically treating for 2 hours, removing the solvent, washing with ethanol, drying at 120 ℃, roasting at 250 ℃ for 3.5 hours, and finally processing to obtain the 80-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used with the following exceptions: preheating isobutene to 200 ℃, introducing the isobutene into a mixer and a fixed bed at a flow rate of 20g/min, setting the temperature of the fixed bed at 190 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 9MPa, preheating dimethyldioxane to 95 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at a flow rate of 3g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 12 hours continuously, and finally calculating to obtain the yield of the 3-methyl-3-butene-1-ol, wherein the yield of the 3-methyl-3-butene-1-ol is 97.4%.
Example 4
Preparation of the catalyst
Weighing 500g of silicon oxide, adding into a flask, taking 40g of strontium oxide and 30g of magnesium oxide, adding dilute nitric acid to dissolve metal oxides, adding into the flask, placing into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 8 hours, standing for 12 hours, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, solidifying for 7.5 hours, filtering, cleaning for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 130 ℃, and roasting at 530 ℃ for 8 hours to obtain the composite metal catalyst. Weighing 25g of caprolactam, adding toluene to dissolve the caprolactam, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating the mixture to 110 ℃, stirring or ultrasonically treating the mixture for 7 hours, removing the solvent, washing the mixture by using ethanol, drying the mixture at 130 ℃, roasting the mixture for 5 hours at 250 ℃, and finally processing the mixture to obtain the 80-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used, except that: preheating isobutene to 160 ℃, introducing the isobutene into a mixer and a fixed bed at the flow rate of 30g/min, setting the temperature of the fixed bed at 170 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 9MPa, preheating dimethyldioxane to 110 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at the flow rate of 4g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 12 hours continuously, and finally obtaining the yield of the 3-methyl-3-butene-1-ol by calculation, wherein the yield of the 3-methyl-3-butene-1-ol is 97.2%.
Example 5
Preparation of the catalyst
Weighing 500g of molecular sieve, adding into a flask, taking 15g of barium oxide and 25g of magnesium oxide, adding dilute nitric acid to dissolve metal oxide, adding into the flask, placing into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 4h, standing for 6h, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, solidifying for 4.5h, filtering, cleaning for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 130 ℃, and roasting at 530 ℃ for 6h to obtain the composite metal catalyst. Weighing 8g of caprolactam, adding toluene to dissolve the caprolactam, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating the mixture to 110 ℃, stirring or ultrasonically treating the mixture for 5 hours, removing the solvent, washing the mixture with ethanol, drying the mixture at 130 ℃, roasting the mixture for 4 hours at 250 ℃, and finally processing the mixture to obtain the 70-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used with the following exceptions: preheating isobutene to 160 ℃, introducing the isobutene into a mixer and a fixed bed at a flow rate of 80g/min, setting the temperature of the fixed bed at 180 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 10MPa, preheating dimethyldioxane to 120 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at a flow rate of 12g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 12 hours continuously, and finally obtaining the yield of the 3-methyl-3-butene-1-ol by calculation, wherein the yield of the 3-methyl-3-butene-1-ol is 97.7%.
Example 6
Preparation of the catalyst
Weighing 500g of molecular sieve, adding into a flask, taking 50g of manganese oxide and 12g of barium oxide, adding dilute nitric acid to dissolve metal oxide, adding into the flask, placing into an ultrasonic container for mixing, ultrasonically treating the mixed solution for 7h, standing for 8h, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, solidifying for 7.5h, filtering, cleaning for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 130 ℃, and roasting at 530 ℃ for 8h to obtain the composite metal catalyst. Weighing 22g of dimethylaniline, adding toluene to dissolve the dimethylaniline, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating the mixture to 110 ℃, stirring or ultrasonically treating the mixture for 8 hours, then removing the solvent, washing the mixture by using ethanol, drying the mixture at 130 ℃, roasting the mixture for 5 hours at 250 ℃, and finally processing the mixture to obtain the 65-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used with the following exceptions: preheating isobutene to 190 ℃, introducing the isobutene into a mixer and a fixed bed at a flow of 10g/min, setting the temperature of the fixed bed at 200 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 7MPa, preheating dimethyldioxane to 110 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at a flow rate of 2g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 12 hours continuously, and finally obtaining the yield of the 3-methyl-3-butene-1-ol by calculation, wherein the yield of the 3-methyl-3-butene-1-ol is 97.1%.
Example 7
Preparation of the catalyst
Weighing 500g of molecular sieve, adding into a flask, taking 30g of barium oxide and 6g of tin oxide, adding dilute nitric acid to dissolve metal oxide, adding into the flask, placing into an ultrasonic container for mixing, carrying out ultrasonic treatment on the mixed solution for 5.5h, standing for 7h, adding ammonium bicarbonate, adjusting the pH value of the solution to 11, carrying out solidification for 6.5h, filtering, washing for three times by using pure water to obtain a solid catalyst, drying the solid catalyst at 125 ℃, and roasting for 6.5h at 480 ℃ to obtain the composite metal catalyst. Weighing 24g of N-phenyl benzylamine, adding toluene to dissolve, mixing 300g of the prepared composite metal catalyst, adding the mixture into an oil bath, heating to 115 ℃, stirring or carrying out ultrasonic treatment for 7.5h, then removing the solvent, washing with ethanol, drying at 130 ℃, roasting at 280 ℃ for 4.5h, and finally processing to obtain the 70-mesh nitrogen-loaded composite metal catalyst.
Experiment for synthesizing 3-methyl-3-buten-1-ol
The synthesis of example 1 was used with the following exceptions: preheating isobutene to 220 ℃, introducing the isobutene into a mixer and a fixed bed at a flow rate of 20g/min, setting the temperature of the fixed bed at 200 ℃, adjusting a back pressure valve to control the pressure of the reactor to be 10MPa, preheating dimethyldioxane to 85 ℃ after the pressure is stable, introducing the dimethyldioxane into the mixer at a flow rate of 4g/min to be mixed with the isobutene, introducing the mixture into the reactor to perform reaction for 24 hours, and finally obtaining the yield of the 3-methyl-3-butene-1-ol by calculation, wherein the yield of the 3-methyl-3-butene-1-ol is 97.4%.
Comparative example 1
According to the prior art, formaldehyde methanol hemiacetal is used as a raw material to synthesize 3-methyl-3-butene-1-alcohol, the formaldehyde methanol hemiacetal is heated to 290 ℃ and pressurized to 19MPa, isobutene is heated to 290 ℃ and pressurized to 19MPa, the formaldehyde methanol hemiacetal and the isobutene are mixed and then enter a tubular reactor to react for 4min, and after the reaction is finished, methanol is separated by rectification, wherein the conversion rate of the formaldehyde methanol hemiacetal is 98.9 percent, and the selectivity is 98.6 percent.
Comparative example 2
According to the prior art, 3-methyl-3-butene-1-ol is synthesized by taking paraformaldehyde as a raw material, firstly, the paraformaldehyde is depolymerized by methylal in a reaction kettle, the temperature is controlled at 150 ℃, and the reaction is carried out for 3 hours to obtain a transparent solution; adding isobutene into a reaction kettle, wherein the mass ratio of olefine to aldehyde is 10, the reaction temperature is 230 ℃, the reaction pressure is 15-16 MPa, the reaction time is 3 hours, discharging reaction materials, and rectifying to separate isobutene, methanol and methylal, wherein the yield of corresponding paraformaldehyde is up to 93.5%.
As shown in comparative example 1, the synthesis of 3-methyl-3-buten-1-ol from formaldehyde-methanol hemiacetal has high temperature and pressure, high requirements from the viewpoint of reactor design and process safety, and high cost, and although the methanol generated by the reaction can be reused after rectification and separation, the energy consumption and cost are increased.
The comparative example 2 shows that the reaction time of 3h for synthesizing the 3-methyl-3-buten-1-ol by reacting the methylal which is synthesized by taking paraformaldehyde as a raw material with isobutene is 3h, the yield is limited due to the extension of the reaction time, and meanwhile, the reactor is a kettle type reactor, so that the problem of difficult design of the reactor exists in the industrial amplification process, and the methanol and the methylal which are generated by the reaction need to be separated, so that the energy consumption is relatively increased.
The method of the invention can better embody the obvious advantages of the invention in the aspects of raw material selection, process conditions, reactor design and the like by combining the comparative example and the method of the invention, and has more value of industrial application.

Claims (18)

1. A method of synthesizing 3-methyl-3-buten-1-ol, the method comprising: in the presence of a catalyst, reacting isobutene with dimethyldioxane to generate 3-methyl-3-buten-1-ol, wherein the reaction temperature of isobutene and dimethyldioxane is 150 to 220 ℃, and the reaction pressure is 4 to 15MPa; the reaction is carried out in an inert atmosphere, the catalyst comprises a main catalyst and an auxiliary catalyst, the main catalyst is a metal oxide, the auxiliary catalyst is a nitrogen-containing compound, and the metal oxide is two or more selected from magnesium oxide, calcium oxide, manganese oxide, barium oxide, iron oxide, copper oxide, zinc oxide, tin oxide and strontium oxide;
the cocatalyst is selected from one or more of imide, carbamide, fatty amine, aromatic amine, nitrogen-containing heterocycle and quaternary ammonium base.
2. The process according to claim 1, wherein dimethyldioxane as a starting material is prepared from formaldehyde and isobutylene under acidic catalyst conditions; the acidic catalyst is one or more of sulfuric acid, phosphoric acid, hydrochloric acid, solid acid and heteropoly acid, and the mass ratio of fed formaldehyde to isobutene is (1) - (8).
3. The process as claimed in claim 2, wherein the dimethyldioxane is prepared at a temperature of from 60 to 100 ℃ and a reaction time of from 4 to 8h.
4. The process as claimed in claim 1, wherein the reaction temperature of isobutene and dimethyldioxane is from 160 to 200 ℃; the reaction pressure is 6MPa to 10MPa.
5. The process of claim 4, wherein the reaction time of the isobutylene and the dimethyldioxane is from 10min to 60min.
6. The process as claimed in claim 5, wherein the reaction time of isobutene with dimethyldioxane is from 15min to 30min.
7. The process as claimed in any one of claims 1 to 6, wherein the molar ratio of isobutene to dimethyldioxane is from 3 to 10:1~5.
8. The process of claim 7 wherein the molar ratio of isobutylene to dimethyldioxane is 5~8:2~4.
9. The process according to any one of claims 1 to 6, wherein the reaction is carried out under a nitrogen atmosphere and in a fixed bed reactor filled with a catalyst.
10. The method according to claim 1, wherein the loading amount of the main catalyst metal oxide is 3 to 40wt% and the loading amount of the cocatalyst nitrogen-containing compound is 1 to 15wt% based on the mass of the carrier.
11. The process of claim 10, wherein the main catalyst metal oxide loading is from 5 to 20wt% and the cocatalyst nitrogen-containing compound loading is from 2 to 5wt%, based on the mass of the carrier.
12. The method of claim 1, wherein the metal oxide is manganese oxide and barium oxide, calcium oxide and iron oxide, copper oxide and zinc oxide, or strontium oxide and magnesium oxide.
13. The method of claim 1, wherein the metal oxide comprises at least one alkaline earth metal oxide and an oxide of at least one selected from iron, copper, tin, manganese, strontium.
14. The process according to any one of claims 1, 12 and 13, wherein the co-catalyst is selected from one or more of phthalimide, propiolactam, caprolactam, dimethylaniline, p-toluidine, methylethylcyclopropylamine, p-chloroaniline, tetradecyldimethylamine, dodecyldimethyl tertiary amine, decaalkyldimethyl tertiary amine, didodecyltrimethyl tertiary amine, dioctadecyltertiary amine, octadecylamine, dioctylamine, didecylamine, dodecylamine, diisooctylamine, isooctylamine, N-pentylamine, N-hexylamine, aminopyridine, pyridine, imidazole, pyrrole, dimethylformamide, triethylamine, N-phenylbenzenemethamine, tetraisopropylamine iodide, and (2-hydroxyethyl) trimethylamine hydroxide.
15. The process of any one of claims 1, 12 and 13, wherein the support comprises one or more of alumina, silica, molecular sieves.
16. The process of any one of claims 1, 12 and 13, wherein the promoter is loaded onto the metal oxide-loaded catalyst support by:
firstly weighing a carrier carrying a main catalyst metal oxide, heating to 50-100 ℃, weighing a nitrogen-containing compound, adding the nitrogen-containing compound into the heated carrier, dissolving and mixing the nitrogen-containing compound and the heated carrier by using an organic solvent, then removing the solvent, washing, drying the obtained nitrogen-containing compound-loaded composite metal catalyst, and further roasting to obtain the nitrogen-containing compound-loaded composite metal catalyst.
17. The method according to any one of claims 1-6, wherein the method comprises the steps of:
(1) Firstly, nitrogen or inert gas is used for purging the reactor, and air in the reactor is completely replaced;
(2) Heating isobutene to the required temperature of 100-300 ℃ through a preheater, and simultaneously preheating dimethyldioxane to the required temperature of 60-140 ℃ through the preheater;
(3) Mixing the two materials through a mixer, continuously feeding the mixed materials into a fixed bed reactor, and reacting under the action of a catalyst to generate 3-methyl-3-butene-1-ol;
(4) And (3) cooling the reaction liquid, then performing pressure rectification separation, separating unreacted isobutene, introducing the residual reaction liquid into a de-heavy rectifying tower, and extracting the 3-methyl-3-butene-1-ol from a lateral line to obtain the high-purity 3-methyl-3-butene-1-ol.
18. The process as claimed in claim 17, wherein in step (2), the isobutylene is passed through a preheater and heated to a desired temperature of 150 to 220 ℃, and the dimethyldioxane is simultaneously passed through the preheater and preheated to a desired temperature of 80 to 120 ℃.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102659518A (en) * 2012-05-04 2012-09-12 大连理工大学 Method for preparing 3-methyl-3-butylene-1-alcohol
CN103073402A (en) * 1999-07-02 2013-05-01 纳特拉斯维特公司 Process for the preparation of 3,3-dimethylbutanal
CN103739442A (en) * 2013-12-03 2014-04-23 江苏苏博特新材料股份有限公司 Preparation method for 3-methyl-3-buten-1-ol
CN109317212A (en) * 2018-11-05 2019-02-12 万华化学集团股份有限公司 Synthesize the catalyst and its preparation method and application of 3- methyl-3-butene-1-alcohol
CN109574799A (en) * 2018-12-05 2019-04-05 厦门大学 A method of 3- methyl-3-butene-1-alcohol is prepared using isobutene and methanol

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103073402A (en) * 1999-07-02 2013-05-01 纳特拉斯维特公司 Process for the preparation of 3,3-dimethylbutanal
CN102659518A (en) * 2012-05-04 2012-09-12 大连理工大学 Method for preparing 3-methyl-3-butylene-1-alcohol
CN103739442A (en) * 2013-12-03 2014-04-23 江苏苏博特新材料股份有限公司 Preparation method for 3-methyl-3-buten-1-ol
CN109317212A (en) * 2018-11-05 2019-02-12 万华化学集团股份有限公司 Synthesize the catalyst and its preparation method and application of 3- methyl-3-butene-1-alcohol
CN109574799A (en) * 2018-12-05 2019-04-05 厦门大学 A method of 3- methyl-3-butene-1-alcohol is prepared using isobutene and methanol

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
A comparative study of an MCM-41 anchored quaternary ammonium chloride/SnCl4 catalyst and its silica gel analogue;TM Jyothi等;《CHEMICAL COMMUNICATION》;20011231;992-993 *
固载化ZnCl_2催化合成3-甲基-3-丁烯-1-醇;刘海超等;《燃料化学学报》;20131231;第41卷(第9期);1146-1152 *
女贞醛的合成研究——实验室阶段报告;金其璋;《香料与香精》;19801231(第02期);1-6 *

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