A process for the preparation of isopentenol from 3-methyl-1-butene

Abstract

The application provides a method for preparing isoamylene alcohol from 3-methyl-1-butene, which comprises: oxidizing 3-methyl-1-butene to obtain a 2-isopropyl oxirane intermediate, and then isomerizing the intermediate to obtain isoamylene alcohol. The synthetic route is novel, 3-methyl-1-butene, a cheap by-product of refining C5, is used as a starting material, and isoamylene alcohol is prepared through two-step reactions of epoxidation and isomerization, which is simple and efficient, and an economic and feasible route for preparing the product is provided. In the second step of isomerization, lithium phosphate treated by sodium alcohol or potassium alcohol is used as a catalyst to efficiently realize the isomerization of the epoxy intermediate, and isoamylene alcohol is conveniently and quickly prepared.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a method for preparing isopentenol from 3-methyl-1-butene through a two-step reaction involving epoxidation and isomerization. Background Technology

[0002] Isopentenol, scientifically known as 3-methyl-2-buten-1-ol, is a colorless, transparent liquid at room temperature. It is readily soluble in water (solubility of 170 g / L) and miscible in common organic solvents such as ethanol, ether, and ethyl acetate. The isopentenol molecule contains double bonds and hydroxyl functional groups, making it a crucial synthetic intermediate. It is widely used in the production of various fine chemicals, such as citral, vitamin A, vitamin E, vitamin K, pyrethroid insecticides, and polycarboxylate superplasticizers.

[0003] Although there are many methods for synthesizing isopentenol, few have practical applications. Industrially, isobutylene and formaldehyde are the main raw materials. They undergo the Prince reaction to yield isopentenol, which then undergoes a hydroisomerization reaction under a catalyst to finally produce isopentenol. This method uses readily available and inexpensive starting materials, making it a highly competitive synthetic route. However, the first step, the Prince reaction, requires high temperature and pressure, resulting in demanding reaction conditions and significant equipment investment. Furthermore, in the hydroisomerization reaction, isopentenol readily undergoes hydrogenation to yield the byproduct isopentenol, resulting in a low hydroisomerization yield of only about 90%.

[0004]

[0005] Some literature reports the use of acetone and acetylene as raw materials. First, the two react to yield methylbutynol, which is then selectively hydrogenated to give methylbutenol. The latter undergoes intramolecular 1,3-hydroxy isomerization under the action of an isomerizing catalyst, ultimately yielding isopentenol. Although the starting materials for this route are relatively inexpensive and readily available, the synthetic route is lengthy and involves flammable and explosive acetylene, posing a significant risk. Therefore, almost no manufacturers currently use this method for the production of isopentenol.

[0006]

[0007] Isoprene can also be used as a raw material for the synthesis of isopentenol. The specific route is shown below: isoprene undergoes addition with hydrogen chloride to obtain isopentenyl chloride, which is then directly hydrolyzed or reacted with sodium acetate to obtain isopentenol acetate, followed by hydrolysis to obtain isopentenol alcohol. Currently, few manufacturers use this route to produce isopentenol because it is not only a long synthetic route but also suffers from problems such as corrosion from hydrogen chloride and acetic acid, and a poor yield from hydrogen chloride addition. Compared to the previously mentioned synthetic route, this method also generates more wastewater.

[0008]

[0009] In summary, the main synthetic methods for isopentenol currently include the isobutylene method, the acetone-acetylene method, and the isoprene method. The isobutylene method is currently the main industrial production method. However, each synthetic route still has drawbacks such as harsh reaction conditions, low yield, and a large amount of waste. In order to obtain isopentenol more economically and cost-effectively, it is urgent to develop novel synthetic routes to prepare isopentenol from inexpensive raw materials in a green, efficient, and low-cost manner, thereby promoting the development of downstream products and applications of isopentenol. Summary of the Invention

[0010] The purpose of this invention is to provide an efficient synthetic route for isopentenol, using 3-methyl-1-butene as a starting material, and obtaining the isopentenol product through a two-step reaction involving epoxidation and isomerization. This synthetic route is concise, operates under mild conditions, and yields a high overall yield, demonstrating significant potential application value.

[0011] To achieve the above objectives and technical effects, the present invention adopts the following technical solution:

[0012] A method for synthesizing isopentenol specifically includes: using 3-methyl-1-butene as a raw material, 3-methyl-1-butene undergoes an epoxidation reaction by peroxide oxidation under the action of an epoxidation catalyst to obtain a 2-isopropylethylene oxide intermediate, which then undergoes an intramolecular isomerization reaction under the action of an isomerization catalyst to obtain the isopentenol product.

[0013] The reaction route is shown below:

[0014]

[0015] In this invention, the peroxide may be, but is not limited to, hydrogen peroxide, tert-butyl hydrogen peroxide, tert-butyl peroxide, phenyl ethane peroxide, isopropylbenzene peroxide, peracetic acid, etc., with hydrogen peroxide being preferred; the peroxide is used in the form of a solution, and the concentration of the solution is preferably 30-50%;

[0016] Preferably, the molar ratio of the peroxide to 3-methyl-1-butene is 1:1.5-3.0.

[0017] In this invention, the epoxidation catalyst may be titanium silicate molecular sieves TS-1, TS-2, Ti-Beta, Ti-MCM-22, Ti-MCM-41, Ti-SBA-15, Ti-MWW, Ti-HMS, Ti-MOR, Ti-TUN, Ti-ZSM-5, and phosphotungstic heteropolyacid quaternary ammonium salts, etc.

[0018] Preferably, the amount of catalyst used is 0.5-2.5 wt% of the mass of the peroxide solution.

[0019] In this invention, the solvent for the epoxidation reaction can be, but is not limited to, toluene, tetrahydrofuran, methyl tert-butyl ether, dichloromethane, dichloroethane, ethyl acetate, methanol, ethanol, acetonitrile, etc.; preferably methanol, acetonitrile, etc.; the mass ratio of the solvent to the peroxide solution is preferably 2.0-5.0:1.0.

[0020] In this invention, the epoxidation reaction can be carried out on equipment such as batch reactors, continuous reactors, and tubular reactors;

[0021] Preferably, the reaction temperature is 50-80℃; and / or the reaction time is 0.5-6.0 hours; and / or the epoxidation reaction is carried out under the protection of gases such as nitrogen and argon, with a gas pressure of 0.5-3.0 MPa.

[0022] In this invention, the isomeric catalyst is a lithium phosphate catalyst treated with sodium alkoxide and / or potassium alkoxide; the treatment method is as follows: lithium phosphate powder is added to an alcohol solution of sodium alkoxide or potassium alkoxide, stirred and displaced at room temperature for 2-6 hours, and then filtered, dried and granulated to obtain the catalyst.

[0023] The sodium or potassium alkoxide may be, but is not limited to, sodium methoxide, sodium ethoxide, sodium tert-butoxide, sodium isopropoxide, potassium methoxide, potassium ethoxide, potassium isopropoxide, potassium tert-butoxide, etc., and the amount used is 4-11 mol% of lithium phosphate.

[0024] In this invention, the preferred solvents for processing lithium phosphate are methanol, ethanol, isopropanol, tert-butanol, etc.; the amount of solvent used is 3-5 times the mass of lithium phosphate.

[0025] The treatment method causes a certain degree of lithium-sodium or lithium-potassium ion exchange on the surface of lithium phosphate, thereby enhancing the alkalinity of the lithium phosphate catalyst and improving its activity.

[0026] In this invention, the weight hourly space velocity (WHSV) of the isomerization reaction is 0.2-2.0 h⁻¹. -1 Preferably 0.5-2.0h -1 The catalyst has a diameter of 1-4 mm, a length of 2-3 mm, and a bulk density of 0.6-0.8 g / mL; the solid catalyst and ceramic θ rings are mixed and packed together.

[0027] In this invention, the temperature of the isomerization reaction is preferably 250-300°C, the reaction pressure is atmospheric pressure, and the carrier gas is preferably nitrogen.

[0028] In this invention, the feed liquid for the isomerization reaction may have a solvent added or may not have a solvent added, preferably without a solvent added; if a solvent is added, the solvent may be, but is not limited to, ethyl acetate, tetrahydrofuran, methyl tert-butyl ether, ethanol, acetonitrile, diethyl ether, etc.

[0029] The present invention, by adopting the above technical solution, has the following positive effects:

[0030] 1. The synthetic route used in this method is novel. Starting with inexpensive C5 refining byproduct 3-methyl-1-butene, isoprenol is prepared in a simple and efficient manner through two-step reactions including epoxidation and isomerization. This provides an economical and feasible route for the preparation of this product and has good potential application value.

[0031] 2. This invention uses lithium phosphate treated with sodium alkoxide or potassium alkoxide as a catalyst to efficiently realize the isomerization reaction of epoxy intermediates and obtain isopentenol product in high yield. Detailed Implementation

[0032] The present invention is described in detail below through embodiments, but the present invention is not limited to the embodiments described below.

[0033] The main raw material information is as follows:

[0034] 3-Methyl-1-butene, AR, Aladdin reagent;

[0035] Hydrogen peroxide (50%), hydrogen peroxide (30%), tert-butyl hydrogen peroxide (30%), Bailingwei reagent;

[0036] Peroxyphenyl ethane (40%), peroxyisopropylbenzene (35%), and chili pepper reagent.

[0037] Ti-MWW, Ti-MCM-22, Ti-ZSM-5, phosphotungsten heteropolyacid quaternary ammonium salt, Zibo Catalytic Molecular Sieve Company.

[0038] The gas chromatography test conditions of this invention are as follows:

[0039] Instrument model: Agilent 8890B; Column: HP-3 capillary column (30m × 0.30mm × 0.25μm); Initial temperature 60℃, increased to 120℃ at a rate of 5℃ / min; then increased to 200℃ at a rate of 10℃ / min and held for 10.0 min. Carrier gas: high-purity nitrogen, split ratio 30:1, split flow rate 42mL / min. Carrier gas saving: 19mL / min, initial waiting time 5.0 min. Injection temperature 250℃, detector: FID, detector temperature 250℃, air flow rate 350mL / min, hydrogen flow rate 30mL / min, make-up gas flow rate 60mL / min, injection volume 0.2μL.

[0040] Example 1:

[0041] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0042] In air, at room temperature, acetonitrile (81.6 g) and Ti-MWW (0.82 g) titanium silicate molecular sieve catalyst were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. Then, a leak test was performed using 2.0 MPaG nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was vented to atmospheric pressure, and the autoclave was stirred. Then, 3-methyl-1-butene (84.2 g, 1.2 mol) and hydrogen peroxide (40.8 g, 0.6 mol, 50 wt%) were added to the autoclave using a metering pump. Finally, 2.0 MPaG nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 60°C. The reaction was carried out under uniform stirring (400 rpm). Four hours after the reaction, samples were taken using a dual-valve system. After adding the internal standard cyclohexane, the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution were analyzed by GC. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the hydrogen peroxide conversion rate was >99.7%, and the selectivity for 2-isopropylethylene oxide was 94.5%.

[0043] Example 2:

[0044] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0045] In air, at room temperature, acetonitrile (173.5 g) and Ti-MWW (0.17 g) catalyst were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was released to atmospheric pressure. The autoclave was then stirred, and 3-methyl-1-butene (53.7 g, 0.765 mol) and hydrogen peroxide (34.7 g, 0.51 mol, 50 wt%) were added to the autoclave via a metering pump. Finally, 3.0 MPaG of nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 80°C. The reaction was carried out under uniform stirring (400 rpm). After 0.5 hours of reaction, samples were taken using a dual-valve system. Following the addition of the internal standard cyclohexane, GC analysis was performed to determine the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the hydrogen peroxide conversion rate was >99.3%, and the selectivity for 2-isopropylethylene oxide was 92.3%.

[0046] Example 3:

[0047] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0048] In air, at room temperature, acetonitrile (156.5 g) and Ti-MWW (1.04 g) catalyst were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was released to atmospheric pressure. The autoclave was then stirred, and the substrate 3-methyl-1-butene (96.8 g, 1.38 mol) and hydrogen peroxide (52.2 g, 0.46 mol, 30 wt%) were added to the autoclave via a metering pump. Finally, 0.5 MPaG of nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 50°C. The reaction was carried out under uniform stirring (400 rpm). Four hours after the reaction, samples were taken using a dual-valve system. After adding the internal standard cyclohexane, the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution were analyzed by GC. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the hydrogen peroxide conversion rate was >99.8%, and the selectivity for 2-isopropylethylene oxide was 94.0%.

[0049] Example 4:

[0050] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0051] In air, at room temperature, toluene (793.0 g) and Ti-MCM-22 (3.97 g) catalyst were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. Then, a leak test was performed using 2.0 MPaG nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was vented to atmospheric pressure, and the autoclave was stirred. Then, 3-methyl-1-butene (115.7 g, 1.65 mol) and tert-butyl hydrogen peroxide solution (198.3 g, 0.66 mol, 30 wt%, tert-butanol as solvent) were added to the autoclave via a metering pump. Finally, 2.0 MPaG nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 60°C. The reaction was carried out under uniform stirring (400 rpm). Four hours after the reaction, samples were taken using a dual-valve system. After adding the internal standard cyclohexane, the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution were analyzed by GC. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the conversion rate of tert-butyl hydroperoxide was >99.0%, and the selectivity for 2-isopropylethylene oxide was 93.9%.

[0052] Example 5:

[0053] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0054] In air, at room temperature, acetonitrile (248.7 g) and Ti-ZSM-5 (2.49 g) titanium silicate molecular sieve catalyst were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. Then, a leak test was performed using 2.0 MPaG nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was vented to atmospheric pressure, and the autoclave was stirred. Then, 3-methyl-1-butene (75.8 g, 1.08 mol) and a phenylene peroxide solution (123.45 g, 0.36 mol, 40 wt%, phenylene ethane as solvent) were added to the autoclave via a metering pump. Finally, 2.0 MPaG nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 60°C. The reaction was carried out under uniform stirring (400 rpm). Four hours after the reaction, samples were taken using a dual-valve system. After adding the internal standard cyclohexane, the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution were analyzed by GC. The conversion and selectivity of the epoxidation reaction were then calculated. The results showed that the conversion of peroxyphenylethane was >99.7%, and the selectivity of 2-isopropylethylene oxide was 98.9%.

[0055] Example 6:

[0056] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0057] In air, at room temperature, dichloromethane (296 g) and phosphotungstic acid quaternary ammonium salt (1.48 g) were added sequentially to a 500 mL autoclave. The autoclave was sealed, and the air inside was purged with nitrogen three times. Then, a leak test was performed using 2.0 MPaG nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was vented to atmospheric pressure, and the autoclave was stirred. Then, 3-methyl-1-butene (71.5 g, 1.02 mol) and cumene peroxide solution (147.8 g, 0.34 mol, 35 wt%, cumene solvent) were added to the autoclave via a metering pump. Finally, 2.0 MPaG nitrogen was introduced. The autoclave jacket heating was turned on, and the temperature inside the reactor was controlled at 60°C. The reaction was carried out under uniform stirring (400 rpm). After 5 hours of reaction, samples were taken using a dual-valve system. Following the addition of the internal standard cyclohexane, GC analysis was performed to determine the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the conversion rate of peroxyisopropylbenzene was >99.3%, and the selectivity for 2-isopropylethylene oxide was 97.4%.

[0058] Example 7:

[0059] Epoxidation of 3-methyl-1-butene to prepare 2-isopropylethylene oxide

[0060] In air, at room temperature, acetonitrile (245g) and Ti-MWW (0.98g) titanium silicate molecular sieve catalyst were added sequentially to a 500mL autoclave. The autoclave was sealed, and the air inside was purged three times with nitrogen. Then, a leak test was performed using 2.0MPaG nitrogen. After confirming there were no leaks, the nitrogen in the autoclave was vented to atmospheric pressure, and the autoclave was stirred. Then, 3-methyl-1-butene (151.5g, 2.16mol) and hydrogen peroxide (49.0g, 0.72mol, 50wt%) were added to the autoclave using a metering pump. Finally, 2.0MPaG nitrogen was introduced. The jacket heating of the autoclave was turned on, and the temperature inside the reactor was controlled at 60℃. The reaction was carried out under uniform stirring (400rpm). Four hours after the reaction, samples were taken using a dual-valve system. After adding the internal standard cyclohexane, the concentrations of the reactant 3-methyl-1-butene and the target product 2-isopropylethylene oxide in the reaction solution were analyzed by GC. The conversion rate and selectivity of the epoxidation reaction were then calculated. The results showed that the hydrogen peroxide conversion rate was >99.8%, and the selectivity for 2-isopropylethylene oxide was 96.8%.

[0061] Example 8:

[0062] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0063] The lithium phosphate catalyst used was lithium phosphate treated with sodium ethoxide. The treatment method was as follows: 50g of lithium phosphate was added to a 200g ethanol solution of sodium ethoxide (2.94g) to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and sodium ions in the lithium phosphate solid. After stirring and displacement for 4 hours, the solution was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with sodium ethoxide, with a diameter of 1-2mm and a length of 2-3mm.

[0064] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 20 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 280 °C. The heating tracing of the vaporization tank was turned on to raise its temperature to 200 °C. After the temperatures of the vaporization tank and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporization tank at a feed rate of 0.33 g / min and a liquid hourly space velocity (LHSV) of 0.4 h⁻¹. -1After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gas. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion rate of ~76% and an isopentenol selectivity of ~99%.

[0065] Example 9:

[0066] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0067] The lithium phosphate catalyst used was lithium phosphate treated with sodium ethoxide. The treatment method was as follows: 50g of lithium phosphate was added to a solution of 150g of sodium ethoxide (1.47g) in ethanol to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and sodium ions in the lithium phosphate solid. After stirring and displacement for 2 hours, the suspension was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with sodium ethoxide, with a diameter of 1-2mm and a length of 2-3mm.

[0068] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 15 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 250 °C. The heating tracing of the vaporization tank was turned on to raise its temperature to 200 °C. After the temperatures of the vaporization tank and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporization tank at a feed rate of 0.17 g / min and a liquid hourly space velocity (LHSV) of 0.2 h⁻¹. -1 After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gas. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion rate of ~71% and isopentenol selectivity of ~99%.

[0069] Example 10:

[0070] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0071] The lithium phosphate catalyst used was lithium phosphate treated with sodium methoxide. The treatment method was as follows: 50g of lithium phosphate was added to a methanol (150g) solution containing 2.33g of sodium methoxide to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and sodium ions in the lithium phosphate solid. After stirring and displacement for 6 hours, the solution was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with sodium methoxide, with a diameter of 1-2mm and a length of 2-3mm.

[0072] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 50 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 300 °C. The heating tracing of the vaporization tank was turned on to raise its temperature to 220 °C. After the temperatures of the vaporization tank and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporization tank at a feed rate of 1.67 g / min and a liquid hourly space velocity (LHSV) of 2.0 h⁻¹. -1 After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gas. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion rate of ~83% and an isopentenol selectivity of ~96%.

[0073] Example 11:

[0074] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0075] The lithium phosphate catalyst used was lithium phosphate treated with sodium tert-butoxide. The treatment method was as follows: 50g of lithium phosphate was added to a solution of 4.15g of sodium tert-butoxide in 250g of tert-butoxide to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and sodium ions in the lithium phosphate solid. After stirring and displacement for 4 hours, the suspension was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with sodium tert-butoxide, with a diameter of 1-2mm and a length of 2-3mm.

[0076] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 35 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 280 °C. The heating tracing of the vaporizer was turned on to raise its temperature to 200 °C. After the temperatures of the vaporizer and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporizer at a feed rate of 1.17 g / min and a liquid hourly space velocity (LHSV) of 1.4 h⁻¹. -1 After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gas. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion of ~75% and isopentenol selectivity of ~98%.

[0077] Example 12:

[0078] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0079] The lithium phosphate catalyst used was lithium phosphate treated with potassium tert-butoxide. The treatment method was as follows: 50g of lithium phosphate was added to a solution of 4.85g of potassium tert-butoxide in 150g of tert-butanol to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and potassium ions in the lithium phosphate solid. After stirring and displacement for 5 hours, the suspension was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with potassium tert-butoxide, with a diameter of 1-2mm and a length of 2-3mm.

[0080] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 30 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 270 °C. The heating tracing of the vaporization tank was turned on to raise its temperature to 200 °C. After the temperatures of the vaporization tank and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporization tank at a feed rate of 0.5 g / min and a liquid hourly space velocity (LHSV) of 0.6 h⁻¹. -1After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gases. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion rate of ~73% and an isopentenol selectivity of ~98%.

[0081] Example 13:

[0082] Gas-phase isomerization of 2-isopropylethylene oxide to synthesize isopentenol

[0083] The lithium phosphate catalyst used was lithium phosphate treated with potassium isopropoxide. The treatment method was as follows: 50g of lithium phosphate was added to a solution of 4.24g of potassium isopropoxide in 200g of isopropanol to obtain a suspension. The suspension was stirred at room temperature to promote the exchange of some lithium ions and potassium ions in the lithium phosphate solid. After stirring and displacement for 5 hours, the suspension was filtered, dried, and then ground, extruded and granulated to obtain the lithium phosphate catalyst treated with potassium isopropoxide with a diameter of 1-2mm and a length of 2-3mm.

[0084] A tubular reactor was used for the gas-phase isomerization reaction. The reactor tube was 40 cm long and 2.5 cm in inner diameter. 50 g of lithium phosphate catalyst and ceramic θ-rings were mixed and packed into the reactor tube. During the gas-phase isomerization reaction, the inlet and outlet valves of the N2 carrier gas were first opened, and the nitrogen carrier gas was started at a flow rate of 40 mL / min. The heating jacket of the reactor tube was turned on to raise the temperature of the reactor tube to 280 °C. The heating tracing of the vaporizer was turned on to raise its temperature to 210 °C. After the temperatures of the vaporizer and the reactor tube stabilized, the metering pump was turned on to pump the feedstock 2-isopropylethylene oxide into the vaporizer at a feed rate of 0.83 g / min and a liquid hourly space velocity (LHSV) of 1.0 h⁻¹. -1 After the raw materials are vaporized, they mix with N2 and pass through the catalyst bed, where an isomerization reaction occurs on the catalyst surface. The reaction gas phase exits the reaction tube and enters a cooler for rapid cooling, then enters a phase separation tank. Unreacted raw materials and products become liquid phases and remain in the tank; the carrier gas N2 and other non-condensable gases are discharged as tail gas. A sampler is located on the pipeline between the cooler and the phase separation tank. Samples are taken periodically using the sampler, and GC chromatography analysis of the reaction liquid composition shows a 2-isopropylethylene oxide conversion of ~75% and isopentenol selectivity of ~99%.

Claims

1. A method for preparing isopentenol, comprising: Under the action of an epoxidation catalyst, peroxide oxidizes 3-methyl-1-butene to undergo an epoxidation reaction, yielding a 2-isopropylethylene oxide intermediate. This intermediate undergoes an intramolecular isomerization reaction under the action of an isomerization catalyst to obtain isopentenol. The isomerization catalyst is a lithium phosphate catalyst treated with sodium alkoxide and / or potassium alkoxide. The treatment method is as follows: lithium phosphate is added to an alcoholic solution of sodium alkoxide and / or potassium alkoxide, stirred and displaced at room temperature for a period of time, and then filtered, dried, and granulated.

2. The method according to claim 1, wherein, The peroxide includes at least one of hydrogen peroxide, tert-butyl hydrogen peroxide, tert-butyl peroxide ether, phenyl ethyl peroxide, isopropyl peroxide, and peracetic acid.

3. The method according to claim 2, wherein, Peroxides are used in solution form with a concentration of 30-50 wt%.

4. The method according to claim 2, wherein, The molar ratio of the peroxide to 3-methyl-1-butene is 1:1.5-3.

0.

5. The method according to any one of claims 1-4, wherein, The epoxidation catalyst is selected from at least one of the following: titanium silicate molecular sieves TS-1, TS-2, Ti-Beta, Ti-MCM-22, Ti-MCM-41, Ti-SBA-15, Ti-MWW, Ti-HMS, Ti-MOR, Ti-TUN, Ti-ZSM-5, and phosphotungstic heteropolyacid quaternary ammonium salts.

6. The method according to claim 5, wherein, The catalyst dosage is 0.5-2.5 wt% of the peroxide solution mass.

7. The method according to any one of claims 1-3, wherein, The epoxidation reaction is carried out at a temperature of 50-80℃; and / or for a reaction time of 0.5-6.0 hours; and / or at a reaction pressure of 0.5-3.0 MPa.

8. The method according to claim 1, wherein, Lithium phosphate is added to an alcoholic solution of sodium alkoxide and / or potassium alkoxide, stirred and displaced at room temperature for 2-6 hours, then filtered, dried and granulated; the catalyst has a diameter of 1-4 mm and a length of 2-3 mm.

9. The method according to claim 1 or 8, wherein, The sodium alkoxide includes at least one selected from sodium methoxide, sodium ethoxide, sodium tert-butoxide, and sodium isopropoxide, and the potassium alkoxide includes at least one selected from potassium methoxide, potassium ethoxide, potassium isopropoxide, and potassium tert-butoxide. The amount of sodium alkoxide and / or potassium alkoxide used is 4-11 mol of lithium phosphate.

10. The method according to claim 1 or 8, wherein, When processing lithium phosphate, the solvent is selected from at least one of methanol, ethanol, isopropanol, and tert-butanol, and the amount of solvent used is 3-5 times the mass of lithium phosphate.

11. The method according to any one of claims 1-4, wherein, The weight hourly space velocity (WHSV) for the isomerization reaction is 0.2–2.0 h⁻¹. -1 .

12. The method according to any one of claims 1-4, wherein, The isomerization reaction occurs at a temperature of 250–300°C.

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