Process for Preparing 1,2-Pentanediol by One-Pot Method from D-Xylose

Abstract

The present invention provides a method for preparing 1,2-pentanediol from D-xylose in one pot. In this method, water is used as the reaction solvent, formic acid is used as the dehydration catalyst, and Pt / mesoporous nitrogen-doped carbon spheres are used as the hydrogenation catalyst. In a high-pressure reactor under a hydrogen atmosphere, 1,2-pentanediol is prepared from D-xylose in one pot. The preparation process of the present invention is simple, the raw materials are easily available, the reaction process is environmentally friendly and pollution-free, and the catalytic system is relatively simple. The raw material conversion rate can reach 100%, and the highest yield of 1,2-pentanediol can reach 40.59%. Moreover, the Pt / mesoporous nitrogen-doped carbon spheres have good stability and can be recycled by simple filtration and drying, which can save resources and reduce costs, and have important application value and are suitable for industrial production and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of 1,2-pentanediol, and particularly relates to a method for preparing 1,2-pentanediol by a one-pot method using D-xylose as a raw material. Background Art

[0002] As the most abundant and cheapest renewable resource on earth, lignocellulosic biomass has attracted much attention due to its wide distribution in nature and good ecological benefits. As one of the three main components of lignocellulosic biomass, hemicellulose can be hydrolyzed into D-xylose, which can be converted into various high-value-added green chemicals. Using chemical methods to efficiently catalytically convert D-xylose into the high-value-added product 1,2-pentanediol has important social and economic significance.

[0003] 1,2-Pentanediol is a key raw material for synthesizing the fungicide propiconazole, and the global consumption is more than 2,000 tons / year. In addition, 1,2-pentanediol can be used as an excellent humectant, and at the same time has an antiseptic effect. It can be formulated into products without preservatives and can improve the water resistance of sunscreen product formulations. 1,2-Pentanediol is mainly applied to various skin care products such as skin care creams, eye creams, skin care lotions, baby care products, and sunscreen products. With the development of its deep processing field and the continuous improvement of people's material living standards, the demand for 1,2-pentanediol is also increasing day by day.

[0004] Currently, industrially, a formic acid solution of 1,2-epoxypentane and calcium hydroxide are used as starting materials, and through processes such as neutralization, hydrolysis, filtration and drying, concentration, extraction, and rectification, high-purity 1,2-pentanediol and calcium formate are obtained. This method has the disadvantages of high prices of the raw materials used, complex production processes, long reaction times, and large preparation costs.

[0005] In addition, Patent CN105622347A discloses a method for preparing 1,2-pentanediol by a one-pot method using a supported Rh or Pd-based hydrogenation catalyst, water as a solvent, and a liquid acid or solid acid as an acid catalyst with D-xylose as a raw material. In this method, the best conversion rate of D-xylose is 74%, the selectivity of 1,2-pentanediol is 44%, and the yield of 1,2-pentanediol is about 33%. However, the catalyst used to achieve this effect is based on SiO2 and supports 5% of the noble metal Rh. The price and loading amount of the noble metal are relatively high, increasing the production cost. At the same time, this catalyst needs to support Mo as an auxiliary agent and ZrO2-SO4 2-As a dehydration catalyst, it increases the complexity of the reaction, and it is difficult to separate the hydrogenation catalyst and the dehydration catalyst. In the preparation method of the core-shell type dehydration (Nb)-hydrogenation (Ru) bifunctional catalyst disclosed in Patent CN113262784B and its application in the preparation of diols from D-xylose, the sum of the yields of ethylene glycol, propylene glycol and 1,2-pentanediol is at most 85%, but this is the total yield of the three, and the specific yield of 1,2-pentanediol is not disclosed. According to the literature published by the author (Applied Catalysis A General, 2018, 561: 41-48) and the master's thesis (Synergistic Catalysis of Acid-Metal Bifunctional Centers for the Preparation of Oxygenated Chemicals from D-Xylose, Ningxia University, 2021), using NbOPO4 as the dehydration catalyst and Ru / C as the hydrogenation catalyst, the highest yield of 1,2-pentanediol prepared from D-xylose under the same active center is 31.4%. This solvent system uses three solvents, γ-valerolactone-water-cyclohexane, which increases the complexity of the reaction, and it is difficult to separate the double solid catalysts. In addition, in the literature (Journal of Fuel Chemistry and Technology, 2021, 49: 1898-1910), a carbon-encapsulated metal catalyst Co@NC with hydrogenation and isomerization activities was prepared and used to catalyze the hydrocracking of D-xylose to prepare 1,2-diols, and the yield of 1,2-pentanediol obtained was 27.4%. Therefore, it is urgent to provide a method for efficiently preparing 1,2-pentanediol by a one-pot method from D-xylose that is pollution-free, low-cost, environmentally friendly and has a high yield. Summary of the Invention

[0006] In order to solve the problem of low yield of 1,2-pentanediol prepared from D-xylose in the prior art, the present invention provides a method for preparing 1,2-pentanediol by a one-pot method from D-xylose with high catalytic activity, easily available raw materials, low cost, environmental friendliness and high yield.

[0007] The method for preparing 1,2-pentanediol by a one-pot method from D-xylose provided by the present invention is as follows: Place D-xylose and water in a high-pressure reactor, add formic acid and a Pt / mesoporous nitrogen-doped carbon sphere catalyst, and under a hydrogen atmosphere, stir and react at 2.5-3.5 MPa and 200 °C for 7-9 hours. After the reaction, cool to room temperature in an ice-water bath, and centrifuge to separate the catalyst to obtain 1,2-pentanediol.

[0008] In the above method for preparing 1,2-pentanediol by a one-pot method from D-xylose, the mass ratio of D-xylose, formic acid and the Pt / mesoporous nitrogen-doped carbon sphere catalyst is 1: 0.5-2: 0.2-0.6, and preferably the mass ratio of D-xylose, formic acid and the Pt / mesoporous nitrogen-doped carbon sphere catalyst is 1: 1: 0.50-0.55.

[0009] In the above method for preparing 1,2-pentanediol by one-pot method using D-xylose, it is preferably stirred and reacted at 3 MPa and 200 °C for 8 hours under a hydrogen atmosphere.

[0010] The preparation method of the above Pt / mesoporous nitrogen-doped carbon sphere catalyst is as follows: Polypyrrole is calcined at 550-650 °C for 1-3 hours under a nitrogen atmosphere to obtain mesoporous nitrogen-carbon microspheres. Then, using the mesoporous nitrogen-carbon microspheres as a carrier, H2PtCl6 is loaded by an impregnation method. Finally, it is reduced at 300-400 °C for 1-3 hours in a mixed atmosphere with a volume ratio of hydrogen to argon of 1:9 to obtain the Pt / mesoporous nitrogen-doped carbon sphere catalyst; based on the mass of the catalyst being 100%, the loading amount of Pt in the Pt / mesoporous nitrogen-doped carbon sphere catalyst is 2%-3%.

[0011] In the preparation method of the above Pt / mesoporous nitrogen-doped carbon sphere catalyst, it is preferably to calcine polypyrrole at 600 °C for 2 hours under a nitrogen atmosphere to obtain mesoporous nitrogen-carbon microspheres.

[0012] In the preparation method of the above Pt / mesoporous nitrogen-doped carbon sphere catalyst, the heating rate of calcining polypyrrole under a nitrogen atmosphere is preferably 1-3 °C / min.

[0013] In the preparation method of the above Pt / mesoporous nitrogen-doped carbon sphere catalyst, it is preferably reduced at 400 °C for 2 hours in a mixed atmosphere with a volume ratio of hydrogen to argon of 1:9.

[0014] In the preparation method of the above Pt / mesoporous nitrogen-doped carbon sphere catalyst, the heating rate of reduction in the mixed atmosphere of hydrogen and argon is preferably 1-3 °C / min.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention uses water as a reaction solvent, formic acid as a dehydration catalyst, and Pt / mesoporous nitrogen-doped carbon sphere catalyst as a hydrogenation catalyst to realize the one-pot preparation of 1,2-pentanediol from D-xylose in a high-pressure reactor under a hydrogen atmosphere. The preparation process of the present invention is simple, the raw materials are easily available, the reaction process is environmentally friendly and pollution-free, and the catalytic system is relatively simple. The raw material conversion rate can reach 100%, and the yield of 1,2-pentanediol can reach up to 40.59% at most. Moreover, the Pt / mesoporous nitrogen-doped carbon sphere catalyst has good stability and can be recycled by simple filtration and drying, which can save resources and reduce costs, has important application value, and is suitable for industrial production and application. Specific Embodiments

[0017] The technical solutions of the present invention will be described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to these embodiments only.

[0018] The Pt / mesoporous nitrogen-doped carbon sphere catalyst used in the following examples was prepared according to the following method:

[0019] Step 1: Dissolve 0.6 g of P123 (a triblock copolymer of polyethylene oxide - polypropylene oxide - polyethylene oxide, produced by Sigma - Aldrich (Shanghai) Trading Co., Ltd., a commercially available product purchased from the market) in 600 mL of water, and stir magnetically overnight to form a homogeneous and transparent aqueous P123 solution (1 mg / mL). Then add 2.1 mL of pyrrole monomer (purchased from Macklin Biochemical Co., Ltd., Shanghai), and stir in a 40 °C constant - temperature water bath for 1 hour, denoted as solution A; dissolve 11.466 g of anhydrous ferric chloride in 113 mL of water, then add 44.3 mL of concentrated hydrochloric acid, and stir in a 40 °C constant - temperature water bath for 10 minutes to obtain solution B; slowly drip solution B into solution A, and the mixed solution gradually changes from colorless and transparent to light green and then quickly turns black; stir and polymerize the mixed solution in a 40 °C constant - temperature water bath for 4 hours to obtain a black solution with polypyrrole precipitate. The solid product is separated by centrifugation (9000 rpm, 6 minutes), washed three times with water and ethanol, and then vacuum - dried at 60 °C for 12 hours. Then, the obtained black powder is heated to 600 °C at a heating rate of 2 °C / min in a nitrogen atmosphere and calcined at a constant temperature for 2 hours to obtain mesoporous nitrogen - doped carbon spheres.

[0020] Step 2: Add 10 mL of water to 0.1 g of mesoporous nitrogen - doped carbon spheres, and ultrasonicate for 30 minutes to obtain a uniformly dispersed solution. Then add an aqueous H2PtCl6 solution (0.1733 mL, 40 mg / mL H2PtCl6) to the obtained solution, ultrasonicate for 30 minutes, stir magnetically at room temperature for 12 hours, then evaporate the solvent to dryness by rotary evaporation, and dry at 100 °C for 12 hours to completely remove water; finally, heat to 400 °C at a heating rate of 2 °C / min in a mixed atmosphere of hydrogen and argon with a volume ratio of 1:9 and reduce at a constant temperature for 2 hours to obtain a Pt / mesoporous nitrogen - doped carbon sphere catalyst, denoted as 2.5% Pt / NC(600) - R400, where 2.5% represents the Pt loading in the catalyst, (600) represents the calcination temperature, and R400 represents the reduction temperature.

[0021] Prepare the catalyst 2.5% Pt / NC(600) - R300 according to the above method.

[0022] Example 1

[0023] Take 0.1869 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.1869 g of formic acid and 0.1 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours until the D-xylose is completely converted. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 , initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 40.59%.

[0024] Example 2

[0025] Take 0.1869 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.2804 g of formic acid and 0.1 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours until the D-xylose is completely converted. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 35.98%.

[0026] Example 3

[0027] Take 0.1869 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.3738 g of formic acid and 0.1 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours until the D-xylose is completely converted. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 35.22%.

[0028] Example 4

[0029] Take 0.1869 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.1869 formic acid and 0.05 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours to completely convert D-xylose. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 37.01%.

[0030] Example 5

[0031] Take 0.2804 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.1869 formic acid and 0.1 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours to completely convert D-xylose. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 39.65%.

[0032] Example 6

[0033] Take 0.3738 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.1869 formic acid and 0.1 g of 2.5% Pt / NC(600)-R400. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours to completely convert D-xylose. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 38.47%.

[0034] Example 7

[0035] Take 0.1869 g of D-xylose and 30 mL of water and place them in a 50 mL high-pressure reactor. Then add 0.1869 formic acid and 0.1 g of 2.5% Pt / NC(600)-R300. Evacuate with N2 at room temperature, and then introduce hydrogen into the high-pressure reactor. Under a hydrogen atmosphere, stir and react at 3 MPa, 200 °C, and 600 rpm for 8 hours to completely convert D-xylose. Cool to room temperature in an ice bath, centrifuge to separate the catalyst, and analyze the product by gas chromatography (carrier gas: nitrogen, flow rate: 2.0 mL·min -1 . Initial column temperature: 40 °C, final column temperature: 250 °C, heating rate: 10 °C / min, hold at 40 °C for 3 min, hold at 160 °C for 1 min, hold at 250 °C for 3 min. Detector temperature: 250 °C), and the yield of 1,2-pentanediol is 37.53%.

[0036] Example 8

[0037] In this example, under a hydrogen atmosphere, stir and react at 2.5 MPa, 200 °C, and 600 rpm for 8 hours. Other steps are the same as in Example 1 to obtain 1,2-pentanediol with a yield of 36.34%.

[0038] Example 9

[0039] In this example, under a hydrogen atmosphere, stir and react at 3.5 MPa, 200 °C, and 600 rpm for 8 hours. Other steps are the same as in Example 1 to obtain 1,2-pentanediol with a yield of 36.87%.

[0040] To determine the process conditions of the present invention, the inventors conducted a large number of laboratory research experiments, specifically as follows:

[0041] 1. Selection of dehydration catalyst

[0042] Take 0.1 g of D-xylose and 30 mL of water and place them in a high-temperature and high-pressure reactor. Respectively add formic acid, acetic acid, oxalic acid, benzoic acid, malonic acid, succinic acid, etc. (the dosage is the same molar amount as formic acid in Example 1) as dehydration catalysts, and add 0.1 g of 2.5% Pt / NC(600)-R400 as a hydrogenation catalyst. Prepare 1,2-pentanediol according to the conditions of Example 1, and the yields of the obtained 1,2-pentanediol are shown in Table 1.

[0043] Table 1 Yields of 1,2-pentanediol prepared by one-pot method of D-xylose catalyzed by different acid catalysts

[0044] Acid catalyst Formic acid Acetic acid Oxalic acid Benzoic acid Malonic acid Succinic acid Yield 40.59％ 36.78％ 20.58％ 26.34％ 22.23％ 28.10％

[0045] As can be seen from Table 1, when formic acid or acetic acid is used as the dehydration catalyst to prepare 1,2-pentanediol, the reaction effect is better, among which formic acid has the best effect, and the yield of 1,2-pentanediol can reach 40.59%.

[0046] 2. Selection of noble metals

[0047] Take 0.1 g of D-xylose and 30 mL of water and place them in a high-temperature and high-pressure reactor. Add 0.1869 g of formic acid as the dehydration catalyst, and respectively add 0.1 g of 2.5% M / NC(600)-R400 loaded with different noble metals as the hydrogenation catalyst. Prepare 1,2-pentanediol according to the conditions of Example 1, and the yields of the obtained 1,2-pentanediol are shown in Table 2.

[0048] Table 2 Yields of 1,2-pentanediol prepared by one-pot method of D-xylose catalyzed by 2.5% M / PPy(600)-R400

[0049] Noble metal M Pt Au Pd Ru Yield 40.59％ 6.96％ 0％ 9.53％

[0050] As can be seen from Table 2, when 2.5% Pt / NC(600)-R400 is used as the hydrogenation catalyst to prepare 1,2-pentanediol, the reaction effect is better, and the yield of 1,2-pentanediol can reach 40.59%.

Claims

1. A method for preparing 1,2-pentanediol by a one-pot method from D-xylose, characterized in that: D-xylose and water are placed in a high-pressure reactor, formic acid and a Pt / mesoporous nitrogen-doped carbon sphere catalyst are added, and under a hydrogen atmosphere, stirring reaction is carried out at 2.5 - 3.5 MPa and 200 °C for 7 - 9 hours. After the reaction, it is cooled to room temperature in an ice-water bath, and the catalyst is separated by centrifugation to obtain 1,2-pentanediol; The mass ratio of the D-xylose, formic acid, and Pt / mesoporous nitrogen-doped carbon sphere catalyst is 1:0.5 - 2:0.2 - 0.6; The preparation method of the Pt / mesoporous nitrogen-doped carbon sphere catalyst is as follows: polypyrrole is calcined at 550 - 650 °C for 1 - 3 hours under a nitrogen atmosphere to obtain mesoporous nitrogen-carbon microspheres. Then, using the mesoporous nitrogen-carbon microspheres as a carrier, H2PtCl6 is loaded by an impregnation method. Finally, reduction is carried out at 300 - 400 °C for 1 - 3 hours in a mixed atmosphere with a volume ratio of hydrogen to argon of 1:9 to obtain the Pt / mesoporous nitrogen-doped carbon sphere catalyst; calculated based on the mass of the catalyst being 100%, the loading amount of Pt in the Pt / mesoporous nitrogen-doped carbon sphere catalyst is 2% - 3%; The preparation method of the polypyrrole is as follows: 0.6 g of P123 is dissolved in 600 mL of water and stirred magnetically overnight to form a uniform and transparent P123 aqueous solution with a concentration of 1 mg / mL. Then, 2.1 mL of pyrrole monomer is added and stirred in a 40 °C constant-temperature water bath for 1 hour, denoted as solution A; 11.466 g of anhydrous ferric chloride is dissolved in 113 mL of water, and then 44.3 mL of concentrated hydrochloric acid is added, and it is stirred in a 40 °C constant-temperature water bath for 10 minutes to obtain solution B; solution B is slowly dropped into solution A, and the mixed solution gradually changes from colorless and transparent to light green and then quickly turns black; the mixed solution is stirred and polymerized in a 40 °C constant-temperature water bath for 4 hours to obtain a black solution with polypyrrole precipitate. The solid product is separated by centrifugation at 9000 rpm for 6 minutes, washed three times with water and ethanol, and then vacuum dried at 60 °C for 12 hours.

2. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1, characterized in that: In the preparation method of the Pt / mesoporous nitrogen-doped carbon sphere catalyst, polypyrrole is calcined at 600 °C for 2 hours under a nitrogen atmosphere to obtain mesoporous nitrogen-carbon microspheres.

3. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1 or 2, characterized in that: In the preparation method of the Pt / mesoporous nitrogen-doped carbon sphere catalyst, the heating rate of calcining polypyrrole under a nitrogen atmosphere is 1 - 3 °C / minute.

4. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1, characterized in that: In the preparation method of the Pt / mesoporous nitrogen-doped carbon sphere catalyst, reduction is carried out at 400 °C for 2 hours in a mixed atmosphere with a volume ratio of hydrogen to argon of 1:

9.

5. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1 or 4, characterized in that: In the preparation method of the Pt / mesoporous nitrogen-doped carbon sphere catalyst, the heating rate of reduction in the mixed atmosphere of hydrogen and argon is 1 - 3 °C / minute.

6. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1, characterized in that: The mass ratio of the D-xylose, formic acid, and Pt / mesoporous nitrogen-doped carbon sphere catalyst is 1:1:0.50 - 0.

55.

7. The method for preparing 1,2-pentanediol by a one-pot method of D-xylose according to claim 1 or 2, characterized in that: Under a hydrogen atmosphere, stirring reaction is carried out at 3 MPa and 200 °C for 8 hours.