A method for preparing 2-butenol compound by liquid-phase 3-butenol compound hydrogen medium environment isomerization

Abstract

This invention provides a method for isomerizing 3-butenol compounds in a hydrogen-medium environment to prepare 2-butenol compounds, comprising the following steps: In a hydrogen atmosphere, a mixture of an inorganic base and a 3-butenol compound is passed through a catalyst bed to undergo an isomerization reaction, yielding the 2-butenol compound; the amount of inorganic base added is 0.01–1.5% of the mass of the 3-butenol compound; the catalyst is porous silica supported on palladium, cerium, and selenium. This invention, by adding an additional base to the 3-butenol feedstock, effectively prevents the unsaturated alcohol from converting to a saturated alcohol during the hydrogen-containing isomerization process. Simultaneously, the addition of the electron promoter selenium to the catalyst in this application inhibits the adsorption capacity of the palladium catalyst for hydrogen, thereby reducing the hydrogenation activity of the palladium catalyst while maintaining the stability of the palladium compound cation. Furthermore, the structure promoter cerium improves the diffusivity of palladium, increases the active centers and coordination of palladium, and structurally improves the performance of the palladium catalyst.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and particularly relates to a method for isomerizing 3-butenol compounds in a hydrogen medium environment in the liquid phase to prepare 2-butenol compounds. Background Technology

[0002] Double bond transfer in unsaturated alcohols is crucial for the synthesis of novel carbonyl derivatives. The double bond transfer catalytic isomerization of 3-methyl-3-butenol to 3-methyl-2-butenol has been widely applied in the production of solvents, dyes, surface coating materials, pigments, pesticides, and citral. Citral is an intermediate in the production of α-ionone and β-ionone, which are essential raw materials for the production of perfumes, fragrances, various household cleaning agents, vitamin A, and pharmaceuticals.

[0003] Currently, zeolite, rhodium complex, and nickel catalysts, among other precious metals, have long been used in double bond transfer processes. However, the selectivity for isomerization in these processes is low, not exceeding 30%. Recently, palladium-supported catalysts have been used to improve reaction performance; however, the irreversible adsorption of unsaturated alcohols by palladium-supported catalysts leads to catalyst deactivation, requiring continuous hydrogen addition to reduce the catalyst's adsorption capacity for unsaturated alcohols and maintain catalyst activity. However, the hydrogenation of unsaturated alcohols can simultaneously cause strong double bond hydrogenation, generating saturated alcohols or byproducts, such as the intermediate n-butane and the hydrogenated final product isoamyl alcohol. Summary of the Invention

[0004] The purpose of this invention is to provide a method for isomerizing 3-butenol compounds in a hydrogen medium environment to prepare 2-butenol compounds. The method of this invention can reduce the conversion of unsaturated alcohols to saturated alcohols during the isomerization process in a hydrogen medium environment, and significantly improve the reactivity and reaction selectivity of 3-butenol compounds.

[0005] This invention provides a method for isomerizing 3-butenol compounds in a hydrogen-medium environment in the liquid phase to prepare 2-butenol compounds, comprising the following steps:

[0006] In a hydrogen atmosphere, a mixture of inorganic base and 3-butenol compound is passed through a catalyst bed to undergo an isomerization reaction to obtain 2-butenol compound.

[0007] The amount of inorganic base added is 0.01 to 1.5% of the mass of the 3-butenol compound;

[0008] The catalyst is porous silica supported on palladium, cerium and selenium.

[0009] Preferably, the inorganic base includes NaOH and / or KOH.

[0010] Preferably, the porous silica in the catalyst has a specific surface area of ​​100–150 m². 2 / g; pore size 3nm~300μm, pore volume 0.8~0.9cm³ 3 / g, of which pores with a diameter in the range of 100 to 300 nm account for 85 to 93% of the total pore volume.

[0011] Preferably, in the catalyst, the mass of palladium is 0.2-0.8% of the total mass of the catalyst, the mass of selenium is 0.02-0.08% of the total mass of the catalyst, and the mass of cerium is 0.1-0.5% of the total mass of the catalyst.

[0012] Preferably, the partial pressure of the hydrogen gas is 0.5 to 5 bar.

[0013] Preferably, the temperature of the isomerization reaction is 50–120°C; the space velocity of the mixture flowing through the catalyst bed is 0.5–5 g / g catalyst × min.

[0014] Preferably, the 3-butenol compound is one or more selected from 3-butenol, 3-methyl-3-butenol, 3,2,1,-trimethyl-3-butenol, 2-isobutyl-3-butenol, 3-(2-hydroxyethyl)-3-butenol, 1-hexyl-3-butenol, 1-methylene-2-methylcyclohexane-3-ol, and 1-methylenecyclopentane-3-ol.

[0015] Preferably, the hydrogen enters from the bottom of the reactor via a gas distributor and a mixture stream, passing through the catalyst bed from bottom to top.

[0016] This invention provides a method for isomerizing 3-butenol compounds in a hydrogen-medium environment to prepare 2-butenol compounds, comprising the following steps: In a hydrogen atmosphere, a mixture of an inorganic base and a 3-butenol compound is passed through a catalyst bed to undergo an isomerization reaction, yielding the 2-butenol compound; the amount of inorganic base added is 0.01–1.5% of the mass of the 3-butenol compound; the catalyst is porous silica supported on palladium, cerium, and selenium. This invention, by adding an additional base to the 3-butenol feedstock, effectively prevents the unsaturated alcohol from converting to a saturated alcohol during the hydrogen-containing isomerization process. Simultaneously, the addition of the electron promoter selenium to the catalyst in this application inhibits the adsorption capacity of the palladium catalyst for hydrogen, thereby reducing the hydrogenation activity of the palladium catalyst while maintaining the stability of the palladium compound cation. Furthermore, the structure promoter cerium improves the diffusivity of palladium, increases the active centers and coordination of palladium, and structurally improves the performance of the palladium catalyst. Detailed Implementation

[0017] This invention provides a method for isomerizing 3-butenol compounds in a hydrogen-medium environment in the liquid phase to prepare 2-butenol compounds, comprising the following steps:

[0018] In a hydrogen atmosphere, a mixture of inorganic base and 3-butenol compound is passed through a catalyst bed to undergo an isomerization reaction to obtain 2-butenol compound.

[0019] The amount of inorganic base added is 0.01 to 1.5% of the mass of the 3-butenol compound;

[0020] The catalyst is porous silica supported on palladium, cerium and selenium.

[0021] In this invention, the isomerization reaction is preferably carried out in a device equipped with a fixed-bed catalyst, such as a tubular reactor. The bottom of the tubular reactor is preferably provided with a gas distributor for uniform distribution of hydrogen. The mixture of inorganic base and 3-butenol compound and hydrogen enter from the bottom of the reactor, pass through the catalyst bed, and carry out the isomerization reaction.

[0022] In this invention, the 3-butenol compound is preferably one or more of 3-butenol, 3-methyl-3-butenol, 3,2,1,-trimethyl-3-butenol, 2-isobutyl-3-butenol, 3-(2-hydroxyethyl)-3-butenol, 1-hexyl-3-butenol, 1-methylene-2-methylcyclohexane-3-ol and 1-methylenecyclopentane-3-ol, and more preferably 3-methyl-3-butenol and its oxo derivatives.

[0023] In this invention, the inorganic base is preferably NaOH and / or KOH. This invention adds an additional base to the starting material for isomerization to prevent and reduce the formation of saturated isopentanol during the catalytic isomerization of isopentenol, which helps to extend catalyst life and ensures stable long-term process operation. The mass of the inorganic base is 0.01–1.5% of the mass of the 3-butenol compound, more preferably 0.05–1%, such as 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, preferably within the range of any of the above values ​​as the upper or lower limit.

[0024] In this invention, the catalyst is a supported noble metal catalyst, preferably porous silica supported with palladium, cerium, and selenium. The specific surface area of ​​the porous silica is preferably 100–150 m². 2 / g; pore size is preferably 3nm~300μm, and pore volume is preferably 0.8~0.9cm³. 3 / g, of which pores with a diameter in the range of 100 to 300 nm account for 85 to 93% of the total pore volume.

[0025] In this invention, in the catalyst, palladium is supported on a silica support in the forms of elemental zero-valent palladium, divalent palladium oxide (PdO), and 3-4 valent palladium oxide, and selenium is supported in the form of SeO. 3,, SeO 2,, SeO oxide is supported on a silica support, and cerium is supported on a silica support in the form of CeO2 and Ce2O3 oxides.

[0026] The mass of palladium is preferably 0.2-0.8% of the total mass of the catalyst, more preferably 0.3-0.7%, such as 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, and preferably within the range of any of the above values ​​as the upper or lower limit; the mass of selenium is preferably 0.02-0.08% of the total mass of the catalyst, more preferably 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, and preferably within the range of any of the above values ​​as the upper or lower limit; the mass of cerium is 0.1-0.5% of the total mass of the catalyst, preferably 0.2-0.4%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and preferably within the range of any of the above values ​​as the upper or lower limit.

[0027] In this invention, the preparation method of the catalyst is as follows:

[0028] Ammonia water is mixed with an alkali metal salt (such as sodium silicate and / or potassium silicate), and then an acid solution such as sulfuric acid aqueous solution is added to generate silica precipitate. The precipitated silica is filtered, washed and spray-dried, and then calcined to obtain silica powder.

[0029] Silica powder and epoxy resin adhesive are mixed to form a paste, which is then pressed into shape to obtain a silica carrier.

[0030] In this invention, the concentration of the ammonia solution is preferably 15-30%, more preferably 20-25%, and the molar ratio of the ammonia solution to the alkali metal salt is preferably 1:(5-10), more preferably 1:(6-8), such as 1:5, 1:6, 1:6.5, 1:7, 1:8, 1:9, 1:10, preferably within the range of any of the above values ​​as the upper or lower limit; the mass concentration of the acid solution is preferably 5-70%, more preferably 9-50%, and most preferably 9-20%; the calcination temperature is preferably 800-900℃, more preferably 850℃; and the calcination time is preferably 10-20 hours, more preferably 15-18 hours.

[0031] After calcination, the moisture content of the calcined silica powder is reduced to 2.5–3 wt% of the total amount of silica powder before calcination. The specific surface area of ​​the calcined silica powder is preferably 90–100 m² / g. 2 / g, with a pore volume preferably of 0.4–0.8 cm³. 3 / g, more preferably 0.6–0.7cm 3 / g, with an average pore size preferably of 18-20 nm, more preferably 19 nm.

[0032] In this invention, the filtration, washing, and spray drying are all commonly used filtration, washing, and spray drying methods in the art, and will not be described in detail here.

[0033] After obtaining silica powder, the present invention mixes silica powder with an adhesive to form a paste, presses it into shape, dries it and then calcines it to obtain a silica cylindrical carrier.

[0034] In this invention, the adhesive is preferably an epoxy resin, such as epoxy resin E44 and / or epoxy resin E51.

[0035] In this invention, the drying temperature is preferably 120–180°C, more preferably 130–150°C, and the drying time is preferably 5–8 hours, more preferably 6–7 hours; the calcination temperature is preferably 600–1000°C, more preferably 700–900°C, and most preferably 800–850°C; the calcination time is preferably 5–10 hours, more preferably 6–8 hours, such as 5 hours, 6 hours, 6.5 hours, 7 hours, 8 hours, 9 hours, 10 hours, preferably within the range of any of the above values ​​as the upper or lower limit.

[0036] In this invention, the partial pressure of hydrogen is preferably 0.5 to 5 bar, more preferably 0.5 to 2 bar, such as 0.5 bar, 1 bar, 1.5 bar, 2 bar, 2.5 bar, 3 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar, and preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0037] In this invention, the temperature of the isomerization reaction is preferably 50-120°C, more preferably 80-100°C, such as 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, and preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0038] The space velocity of the mixture of inorganic base and 3-butenol compound flowing through the catalyst bed is preferably 0.5 to 5 h⁻¹. -1 More preferably 1 to 4 hours -1 , such as 0.5h -1 1h-1 1.5h -1 2h -1 2.5h -1 3h -1 3.5h -1 4h -1 4.5h -1 5h -1 Preferably, the range of values ​​is defined by any of the above values ​​as the upper or lower limit.

[0039] The isomerization process of this invention does not use inert organic solvents as process carriers.

[0040] In this invention, adding a very small proportion of free base to the liquid-phase 3-butenol can keep the palladium, selenium, and cerium multiphase noble metal oxide supported on the acidic support silica under the lowest possible acidity or near-neutral environment, thus maintaining the long-term stable activity of the catalyst.

[0041] In this invention, after the isomerization reaction is completed, the reaction mixture obtained mainly contains 3-butenol, 2-butenol, a small proportion of 3-methyl-2-butenal and trace amounts of pentenal. Among them, 3-methyl-2-butenal is also an important raw material for the preparation of downstream products such as fragrance citral and vitamins E and A.

[0042] This invention provides a method for isomerizing 3-butenol compounds in a hydrogen-medium environment to prepare 2-butenol compounds, comprising the following steps: In a hydrogen atmosphere, a mixture of an inorganic base and a 3-butenol compound is passed through a catalyst bed to undergo an isomerization reaction, yielding the 2-butenol compound; the amount of inorganic base added is 0.01–1.5% of the mass of the 3-butenol compound; the catalyst is porous silica supported on palladium, cerium, and selenium. This invention, by adding an additional base to the 3-butenol feedstock, effectively prevents the unsaturated alcohol from converting to a saturated alcohol during the hydrogen-containing isomerization process. Simultaneously, the addition of the electron promoter selenium to the catalyst in this application inhibits the adsorption capacity of the palladium catalyst for hydrogen, thereby reducing the hydrogenation activity of the palladium catalyst while maintaining the stability of the palladium compound cation. Furthermore, the structure promoter cerium improves the diffusivity of palladium, increases the active centers and coordination of palladium, and structurally improves the performance of the palladium catalyst.

[0043] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a method for preparing 2-butenol compounds by isomerization of 3-butenol compounds in a hydrogen medium environment provided by the present invention, but this should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] Catalyst preparation

[0046] 350 mL of 20% ammonia solution (63.7 g) was added to a 1000 mL stirred tank containing 175 mL of 420 g sodium silicate (water glass, Na₂SiO₃), forming an ammonia-alkali metal salt solution. During stirring, 275 mL of 9% sulfuric acid solution (45.2 g) was added, resulting in a silica precipitate. The precipitated silica was filtered, washed, and spray-dried to obtain silica powder. The silica powder was then calcined at 850 °C for 15 hours to reduce the moisture content to 2.5 wt% of the original silica content. After calcination, the specific surface area of ​​the silica decreased from 137 m² / h. 2 / g reduced to 95m 2 / g, pore volume 0.6cm³ 3 / g, average pore diameter D = 19nm. 27g of epoxy resin E44 as an adhesive and 3g of silica powder were mixed to form a paste, which was then pressed into silica cylinders with a diameter of 3mm and a diameter-to-height ratio of 0.5. These cylinders were dried in a 150℃ drying oven for 6 hours to set their shape. Then, they were calcined at 800℃ for 5 hours to ensure that the moisture content in the silica cylinders containing the adhesive was consistent with the moisture content in the silica powder. The final product was a 30g cylindrical silica carrier with a diameter of 3mm and a diameter-to-height ratio of 0.5.

[0047] A mixture of 13.64 g of palladium nitrate solution containing 11% (wt) palladium, 0.21 g of selenium dioxide (SeO2), and 8.04 g of cerium nitrate with 244 g of water was added to a round-bottom rotary flask. The strip-shaped support was then added, and the mixture was distilled in an evaporator at room temperature until all the solution was absorbed by the support material. The flask containing the catalyst was then heated to 120°C while continuing to rotate at a speed of 9 revolutions per minute for 3 hours, during which time 2000 liters of air were introduced into the flask per hour. The temperature was then increased to 200°C, and the flask was rotated for another 3 hours, during which time 1000 liters of air were introduced into the flask per hour.

[0048] The obtained silica-supported catalyst contains 0.5 wt% palladium, 0.05 wt% selenium, and 0.3 wt% cerium. Its specific surface area is 119 m². 2 / g. Specific surface area was determined according to the nitrogen adsorption method of DIN 66131. ​​The pore volume for pore diameters in the range of 3 nm to 300 μm was 0.82 cm³. 3 / g, with 91.7% of the pores having a diameter in the range of 10–100 μm. The pore volume was determined by the Hg porosity measurement method.

[0049] Heterogeneity

[0050] 24.2 g of catalyst was loaded into a jacketed, heated tubular reactor with a tube bundle inner diameter of 21 mm. A mixture of 100.2 g of 3-methyl-3-butenol and NaOH (0.2% of the 3-methyl-3-butenol feed mass) from a storage tank was pumped into the reactor from the bottom. Hydrogen was metered in from the bottom inlet and evenly distributed across the reactor cross-section via glass fiber. The isomerization temperature was controlled at 90°C by the heat transfer medium in the reactor jacket, and the hydrogen flow rate was metered at 2.1 L / h. The total pressure inside the reactor was 1.1 bar, and the space velocity was 1.0 h⁻¹. -1 (1 gram of 3-methyl-3-butenol / gram of catalyst × minutes).

[0051] Examples 2-5

[0052] Isomerization was carried out according to the process conditions in Example 1, except that the isomerization temperature and hydrogen flow rate in Examples 2 to 5 were carried out according to the parameters in Table 1.

[0053] The isomerized structures are shown in Table 1:

[0054] Table 1. Isomerization results in Examples 1-5

[0055]

[0056] Note: The total amount of the reaction mixture in Table 1 should theoretically be 100%, but due to human error caused by manual operation, such as reactants sticking to the glass tube wall or flask wall, the total amount of the reaction mixture is lower than the theoretical value.

[0057] Comparative Examples 1-5

[0058] Isomerization was carried out according to the technical solutions of Examples 1 to 5, except that alkali was added in all of Examples 1 to 5.

[0059] The isomerized structures are shown in Table 2:

[0060] Table 2. Isomerization results in Comparative Examples 1–5

[0061]

[0062] The results in Tables 1 and 2 show that the selectivity did not change significantly in the presence of free base, but the conversion rate of 2-butenol was significantly improved. Continuous isomerization makes it possible to continuously distill and separate the starting material from the product and recycle the starting material back to isomerization. The isomerization process operates economically overall.

[0063] Comparative Examples 6-8

[0064] Isomerization was carried out according to the process conditions in Example 1, except that the catalyst in Comparative Examples 6-8 was a silica support loaded with only 0.5% palladium and did not contain cerium or selenium.

[0065] The isomerized structures are shown in Table 3:

[0066] Table 3. Isomerization results in Comparative Examples 6–8

[0067]

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 2-butenol compound by hydrogen medium environment isomerization of 3-butenol compound in liquid phase, comprising the following steps: flowing a mixture of inorganic base and 3-butenol compound through a catalyst bed in hydrogen environment to perform isomerization reaction, and obtaining 2-butenol compound; wherein the inorganic base comprises NaOH and / or KOH, and the inorganic base is added in an amount of 0.01-1.5% of the mass of 3-butenol compound; the catalyst is porous silica loaded with palladium, cerium and selenium; the isomerization reaction is performed at a temperature of 80-100℃, and the mixture flows through the catalyst bed at a space velocity of 0.5-5 g / g catalyst x min; in the catalyst, the mass of palladium is 0.2-0.8% of the total mass of the catalyst, the mass of selenium is 0.02-0.08% of the total mass of the catalyst, and the mass of cerium is 0.1-0.5% of the total mass of the catalyst; the hydrogen has a partial pressure of 0.5-5 bar; the 3-butenol compound is one or more of 3-butenol, 3-methyl-3-butenol, 3,2,1,-trimethyl-3-butenol, 2-isobutyl-3-butenol, 3-(2-hydroxyethyl)-3-butenol, 1-hexyl-3-butenol, 1-methylene-2-methylcyclohexane-3-ol and 1-methylene cyclopentane-3-ol; and the hydrogen enters from the bottom of the reactor together with the mixture flow through the catalyst bed from bottom to top via a gas distributor. ​ ​ ​ ​ 2. The method of claim 1, wherein, The specific surface area of the porous silica in the catalyst is 100 to 150 m 2 / g; the pore diameter is 3 nm to 300 μm, and the pore volume is 0.8 to 0.9 cm 3 / g, wherein the volume of the pores having a diameter in the range of 100 to 300 nm accounts for 85 to 93% of the total pore volume.

3. The method of claim 2, wherein, ​ 4. The method of claim 1, wherein, ​ 5. The method of claim 1, wherein, ​ 6. The method of claim 1, wherein, ​

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