Preparation method of C8-C15 biological liquid fuel precursor

Abstract

The present invention discloses a preparation method of a C8-C15 bio-liquid fuel precursor, belonging to the technical field of biomass conversion. The preparation method of the C8-C15 bio-liquid fuel precursor is as follows: Add the substrate furfural, the substrate primary alcohol or secondary alcohol and a certain amount of base into a reaction vessel, heat to a certain temperature, and stir for reaction; After the reaction is completed, filter to obtain a liquid solution containing the target product α,β-unsaturated aldehyde / ketone or unsaturated alcohol, determine the yield by GC and GC-MS analysis, and obtain the pure target product by column chromatography method. The present invention can make the reaction proceed in air, reducing the consumption of O2; at the same time, the reaction temperature is lower, the time is shorter, and no other metal catalyst and other reagents need to be added; the yield is high, the operability is strong, and it can be used for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass conversion, and in particular relates to a method for preparing a C8-C15 bioliquid fuel precursor. Background Art

[0002] With the excessive consumption of fossil fuels and the growing demand for energy in recent years, it has become urgent to find a new, green, clean and sustainable energy source. As a renewable energy source, biomass energy has great potential to replace non-renewable fossil resources to produce high value-added chemicals and biofuels. In addition, biomass energy can absorb carbon dioxide in the natural environment and reduce the content of carbon dioxide in the air, thereby reducing greenhouse gas emissions. Lignocellulose in biomass energy is composed of three major components: cellulose, hemicellulose and lignin. Hemicellulose can be converted into furfural after acid hydrolysis and dehydration. Furfural is a very important bio-based platform compound, which can be converted into many valuable chemicals through hydrogenolysis, oxidative conversion, decarboxylation, acetalization or aldol condensation. Among them, the oxidative condensation reaction of furfural with fatty alcohols can promote the combination of two carbon molecules and produce longer hydrocarbon chains and low-volatility liquid fuels.

[0003] The document (A tunable process: catalytic transformation of renewable furfural with aliphatic alcohols in the presence of molecular oxygen. Chem Commun 2015, 51 (17), 3674-3677) discloses a method for preparing furan-2-propenal, a precursor of C8 bio-liquid fuel, by reacting furfural with n-propanol. Although the final conversion rate and selectivity can reach 94% and 97% respectively, other metal catalysts need to be added in the process, and the reaction temperature is high. The required reaction atmosphere is O2, which is not conducive to production operation.

[0004] The literature (Subnanometric Cu clusters on atomically Fe-doped MoO2 for furfural upgrading to aviation biofuels. Nat Commun 2022, 13 (1), 2591) also reported an operating method for preparing C8-C15 bioliquid fuel precursors by reacting furfural with C3-C10 primary alcohols or C3-C10 secondary alcohols. Although this method has a greatly increased substrate range compared with other methods, the reaction temperature is high, the time is long, the preparation of the required catalyst is complex, and the reaction needs to be carried out under a certain pressure of O2, which makes this method still very difficult to apply in actual production activities. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a C8-C15 bioliquid fuel precursor. The preparation method of the present invention can allow the reaction to be carried out in the air, reducing the consumption of O2; at the same time, the reaction temperature is lower, the time is short, the yield is high, and there is no need to add other metal catalysts and other reagents.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The invention provides a method for preparing a C8-C15 bio-liquid fuel precursor, comprising the following steps: adding furfural, primary alcohol or secondary alcohol and a certain amount of alkali into a reaction container, heating to a certain temperature and stirring for reaction; after the reaction is completed, a liquid solution containing a target product is obtained, and then a column chromatography method is used to obtain a pure target product.

[0008] Furthermore, in the method for preparing the C8-C15 bioliquid fuel precursor of the present invention, the primary alcohol is a C3-C10 straight-chain alcohol.

[0009] Furthermore, in the method for preparing the C8-C15 bioliquid fuel precursor of the present invention, the primary alcohol is n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol or n-decanol.

[0010] Furthermore, in the method for preparing the C8-C15 bioliquid fuel precursor of the present invention, the secondary alcohol is a C4-C8 branched alcohol.

[0011] Furthermore, in the method for preparing the C8-C15 bioliquid fuel precursor of the present invention, the secondary alcohol is secondary butanol, secondary amyl alcohol, secondary hexanol, secondary heptanol or secondary octanol.

[0012] Furthermore, in the method for preparing the C8-C15 bio-liquid fuel precursor of the present invention, the volume of the primary alcohol or secondary alcohol required to be added per 1 mmol of furfural is 5 mL-25 mL.

[0013] Furthermore, in the method for preparing the C8-C15 bio-liquid fuel precursor of the present invention, the base is LiOH, NaOH, KOH, Cs2CO3, KO t Bu、LiO t Bu or NaO t Bu.

[0014] Furthermore, in the method for preparing the C8-C15 bio-liquid fuel precursor of the present invention, the amount of the alkali substance required to be added per 1 mmol of furfural is 0.4 mmol-2.2 mmol.

[0015] Furthermore, in the method for preparing the C8-C15 bioliquid fuel precursor of the present invention, the reaction temperature is 25 to 140°C and the reaction time is 1 to 16 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] First, the preparation reaction of the present invention can be carried out in air, which reduces the consumption of O2;

[0018] Second: The reaction conditions of the present invention are mild and no other metal catalysts or other reagents need to be added, which greatly saves the cost of raw materials and makes the reaction more environmentally friendly;

[0019] Third: The reaction yield of the present invention is high, operability is strong, and it can be used for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The product 1 after the reaction of furfural and n-pentanol in Example 1 of the present invention 1 H NMR spectra;

[0021] Figure 2 The product 2 after the reaction of furfural and n-pentanol in Example 2 of the present invention 1 H NMR spectra;

[0022] FIG3 is a GC-MS diagram of product 1 after the reaction of furfural and n-pentanol in Example 1 of the present invention;

[0023] Figure 4a This is a GC-MS graph of product 1 after the reaction of furfural and n-pentanol in Example 2 of the present invention;

[0024] Figure 4b This is a GC-MS graph of product 2 after the reaction of furfural and n-pentanol in Example 2 of the present invention;

[0025] Figure 5a This is the MS graph of product 4 after the reaction of furfural and sec-butanol in Example 3 of the present invention;

[0026] Figure 5b This is the MS graph of product 5 after the reaction of furfural and sec-butanol in Example 3 of the present invention;

[0027] Figure 5c This is the MS graph of product 6 after the reaction of furfural and sec-butanol in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with embodiments.

[0029] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased.

[0030] Example 1

[0031] Take 1 mmol furfural (96 mg), 10 mL of one of n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol or n-decanol and 80 mg NaO t Bu was added to the pressure tube. The reaction was carried out at 60 ºC for 4 h. After the reaction was completed, the liquid solution containing the target products 1 and 2 was filtered to obtain the yield. The yield was determined by GC and GC-MS analysis. The reaction solution was filtered and the solvent was removed by rotary evaporation to obtain a crude product containing 1 and 2; then column chromatography was performed with a developing solvent of petroleum ether: ethyl acetate = 3:1 to obtain the corresponding pure target products 1 and 2.

[0032] like Figure 1 As shown, product 1 in sequence number 3: 1 H NMR (500 MHz, DMSO- d 6) δ 9.47 (s, 1H), 7.99 (s, 1H), 7.25 (s, 1H), 7.01 (s, 1H), 6.73 (s, 1H), 2.51 (s, 2H), 1.40 (s, 2H), 0.89 (s, 3H).

[0033] The reaction conversion rate and selectivity of different products in this example are shown in Table 1 below.

[0034] Table 1 Oxidative condensation reaction of furfural and different primary alcohols at 60℃ a

[0035]

[0036] a Reaction conditions: 1 mmol furfural (96 mg), 80 mg NaO t Bu, 10 mL alcohol, 60 °C, 4 h; b The data were confirmed by GC and GC-MS analysis; c The reaction temperature was 70°C.

[0037] Example 2

[0038] Take 1 mmol furfural (96 mg), 10 mL of one of n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol or n-decanol and 80 mg NaO t Bu was added to the pressure tube. The reaction was carried out at 100 ºC for 4 h. After the reaction was completed, the liquid solution containing the target products 1 and 2 was filtered to obtain the yield. The reaction conversion rate and the selectivity of different products were shown in Table 2 below. The reaction solution was filtered and the solvent was removed by rotary evaporation to obtain a crude product containing 1 and 2; then, column chromatography was performed with a developing solvent of petroleum ether: ethyl acetate = 3:1 to obtain the corresponding pure target products 1 and 2.

[0039] like Figure 2 As shown, product 2 in sequence number 3: 1 H NMR (500 MHz, DMSO- d 6) δ 7.59 (s, 1H), 6.47 (s, 1H), 6.31 (s, 1H), 6.28 (s, 1H), 5.03 (s, 1H), 3.97 (s, 2H), 2.28 (s, 2H), 1.46 (s, 2H), 0.92 (s, 4H). 1 H NMR spectra;

[0040]

[0041] Table 2 Oxidative condensation reaction of furfural and different primary alcohols at 100℃ a

[0042]

[0043] a Reaction conditions: 1 mmol furfural (96 mg), 80 mg NaO tBu, 10 mL alcohol, 100 °C, 4 h; b The data were confirmed by GC and GC-MS analysis.

[0044] Example 3

[0045] Take 1 mmol furfural (96 mg), 10 mL of sec-butyl alcohol, sec-pentanol, sec-hexanol, sec-heptanol or sec-octanol and 80 mg NaO t Bu was added to the pressure tube. The reaction was carried out at 25 ºC for 4 h. After the reaction was completed, the liquid solution containing the target products 4, 5, and 6 was obtained by filtration. The yield was determined by GC and GC-MS analysis. The reaction conversion rate and the selectivity of different products are shown in Table 3 below. (c: 40℃). The reaction solution was filtered and the solvent was removed by rotary evaporation to obtain a crude product containing 4, 5, and 6; then, column chromatography was performed with a developing solvent of petroleum ether: ethyl acetate = 3:1 to obtain the corresponding pure target products 4, 5, and 6.

[0046] Table 3 Oxidative condensation reaction of furfural and different secondary alcohols a

[0047]

[0048] a Reaction conditions: 1 mmol furfural (96 mg), 80 mg NaO t Bu, 10 mL alcohol, 25 °C, 4 h; b The data were confirmed by GC and GC-MS analysis; c The reaction temperature was 40°C.

[0049] Example 4

[0050] Take 1 mmol furfural (96 mg), 10 mL n-pentanol and 0.84 mmol LiOH, NaOH, KOH, Cs2CO3, KO t Bu、LiO t Bu or NaO t One of Bu was added to a pressure tube. The reaction was carried out at 60 ºC for 4 hours. After the reaction was completed, the liquid solution containing the target products 2-(furan-2-methylene)pentanal and 2-(furan-2-methylene)pentanol was filtered to obtain the yield. The reaction conversion rate and the selectivity of different products are shown in Table 4 below. The reaction solution was filtered and the solvent was removed by rotary evaporation to obtain a crude product containing 8 and 9; then, column chromatography was performed with a developing solvent of petroleum ether: ethyl acetate = 3:1 to obtain the corresponding pure target products 8 and 9.

[0051] Table 4 Oxidative condensation reaction of furfural and n-pentanol catalyzed by different bases a

[0052]

[0053] a Reaction conditions: 1 mmol furfural (96 mg), 0.84 mmol base, 10 mL n-pentanol, 60 °C, 4 h; b The data were confirmed by GC and GC-MS analysis.

[0054] The structural formulas and compound names of the products involved in the present invention are shown in Table 5 below.

[0055] Table 5 Product structure and name

[0056]

[0057] The above embodiments describe the implementation methods of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The above description is only a preferred feasible embodiment of the present invention, and does not limit the scope of rights of the present invention. All equivalent structural changes made by using the contents of the present invention specification are included in the scope of rights of the present invention.

Claims

1. A method for preparing a C8-C15 bio-liquid fuel precursor, characterized in that: The steps are as follows: furfural, primary alcohol or secondary alcohol, and a certain amount of alkali are added into a reaction container, heated to a certain temperature, and stirred for reaction; after the reaction is completed, a liquid solution containing the target product is obtained, and then a column chromatography method is used to obtain a pure target product; The primary alcohol is n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol or n-decanol; The secondary alcohol is secondary butanol, secondary amyl alcohol, secondary hexanol, secondary heptanol or secondary octanol; The base is LiOH, NaOH, LiO t Bu or NaO t Bu; The temperature during the reaction is 25 ~ 100°C; The amount of the base substance required to be added per 1 mmol of furfural is 0.4 mmol-2.2 mmol.

2. The method for preparing a C8-C15 bio-liquid fuel precursor according to claim 1, characterized in that: The volume of primary alcohol or secondary alcohol required to be added for every 1 mmol of furfural is 5 mL-25 mL.

3. The method for preparing a C8-C15 bio-liquid fuel precursor according to claim 1, characterized in that: The reaction time is 1 to 16 h.

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