Method for preparing pentanediol from furfural

Abstract

The invention belongs to the field of catalytic hydrogenation reaction, and provides a method for preparing pentanediol from furfural. The method comprises the following steps: in the presence of a non-noble metal catalyst and isopropanol, contacting furfural with hydrogen for hydrogenation reaction to form a reaction product containing pentanediol; wherein the non-noble metal catalyst is a cobalt-copper binary catalyst and / or a cobalt-zirconium-copper ternary catalyst, and the non-noble metal catalyst is prepared by the method comprising the following steps: (1) carrying out precipitation reaction on a metal source and a precipitator in water, and aging to obtain a solid-liquid product; and (2) carrying out solid-liquid separation on the solid-liquid product, and washing, drying and calcining the obtained solid. According to the method, pentanediol can be prepared under the condition that the low-cost catalyst is adopted, and the yield of pentanediol can be increased.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalytic hydrogenation reaction, and specifically provides a method for preparing pentanediol from furfural. BACKGROUND

[0002] Pentanediol (for example, 1,2-pentanediol, 1,5-pentanediol) is an important chemical raw material as a straight-chain diol compound with both polar and non-polar ends, and is widely used in various fields. Among them, 1,2-pentanediol can be used as a raw material for the synthesis of propiconazole, a fungicide with low toxicity and good vegetable and fruit disease control effect, and 1,2-pentanediol can also be used to make cosmetics and preservatives with biological affinity due to its chemical properties of preservation and moisturizing; 1,5-pentanediol is an important monomer for the synthesis of various saturated or unsaturated polymers (for example, polyester polyols, polyurethane), and can also be used as a green solvent for oil cutting and latex paint due to its good solubility.

[0003] Currently, the industrial production of pentanediol mainly adopts petroleum refining method, that is, using petroleum-based raw materials as the source to produce pentanediol by chemical synthesis method, for example, pentanediol is prepared by hydrogenation conversion of dimethyl glutarate, or 3,4-dihydropyran is first synthesized by condensation of vinyl ether and propylene aldehyde, and then pentanediol is prepared by hydrolysis and hydrogenolysis. However, these methods have problems such as high energy consumption, serious corrosion of equipment by raw materials, high reaction cost, and environmental pollution. Therefore, it is proposed to synthesize pentanediol from biomass resources. Biomass resources have the advantages of wide source, low price, and environmental friendliness, and furfural is one of the few platform chemicals based on biomass industrially produced, which is mainly prepared by acid-catalyzed degradation of hemicellulose, and belongs to biomass-based derivatives. More than 200,000 tons of furfural are produced worldwide every year, so the preparation of pentanediol from furfural, a biomass-based derivative, has become one of the important research directions.

[0004] Currently, the reaction path of furfural hydrogenolysis to pentanediol mainly includes two kinds: the first kind is that furfural is completely hydrogenated to tetrahydrofurfuryl alcohol, and then the C-O bond in the furan ring of tetrahydrofurfuryl alcohol is broken and hydrogenated to obtain pentanediol, and the main product is 1,5-pentanediol; the second kind is that furfural is hydrogenated to produce furfuryl alcohol intermediate, and then the C-O bond in the furan ring of furfuryl alcohol is broken, and then hydrogenation is carried out to obtain pentanediol, and the main product is 1,2-pentanediol. In addition, the reaction of furfural hydrogenolysis to pentanediol is usually carried out in the presence of a metal catalyst, but the cost of noble metal catalyst is too high, and the non-noble metal catalyst has low reaction efficiency and low selectivity to pentanediol, resulting in low yield of pentanediol.

[0005] Therefore, it is still necessary to develop a new method for preparing pentanediol by catalytic hydrogenation using furfural as the raw material and combining a high-performance low-cost catalyst. SUMMARY

[0006] The present invention aims to provide a method for preparing pentanediol from furfural. The method of the present invention can produce pentanediol using a low-cost catalyst and can increase the yield of pentanediol.

[0007] To achieve the above object, the present invention provides a method for preparing pentanediol from furfural, comprising: contacting furfural with hydrogen in the presence of a non-precious metal catalyst and isopropyl alcohol to carry out a hydrogenation reaction to form a reaction product containing pentanediol; wherein the non-precious metal catalyst is at least one of a cobalt-copper binary catalyst and a cobalt-zirconium-copper ternary catalyst, and the non-precious metal catalyst is prepared by a method comprising the following steps:

[0008] (1) subjecting a metal source including a cobalt salt, a copper salt, and optionally a zirconium salt to a precipitation reaction with a precipitant including NaOH and Na2CO3 in water and aging the reaction to obtain a solid-liquid product;

[0009] (2) The solid-liquid product is subjected to solid-liquid separation, and the obtained solid is washed, dried and calcined in sequence.

[0010] In the furfural hydrogenation reaction of the present invention, the catalyst used is an unsupported cobalt-copper and / or cobalt-zirconium-copper multi-component catalyst prepared using NaOH and Na2CO3 as precipitants. This catalyst catalyzes the furfural hydrogenation reaction in isopropyl alcohol, thereby increasing the conversion rate of furfural and the selectivity for the target product, pentanediol (including 1,2-pentanediol and 1,5-pentanediol). Furthermore, by replacing traditional precious metal catalysts with non-precious metal catalysts, the present invention can also reduce the cost of producing pentanediol through furfural hydrogenation.

[0011] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0013] Figure 1 For comparison, the catalyst CoO of Preparation Examples 1 to 5 x 、ZrO x , CuO x , XRD comparison charts of CoZr (5:7), ZrCo (7:2), the catalyst CoCu (5:2) of Preparation Example 1, and the catalyst CoZrCu (5:7:2) of Preparation Example 2;

[0014] Figure 2A scanning electron microscope (SEM-EDS) image of the catalyst CoZrCu (5:7:2) of Preparation Example 2;

[0015] Figure 3 A transmission electron microscope (TEM-EDS) image of the catalyst CoZrCu (5:7:2) of Preparation Example 2. DETAILED DESCRIPTION

[0016] Embodiments of the present application are described in detail below. The embodiments described below are exemplary only and are not to be construed as limiting the present application.

[0017] The ranges disclosed herein are defined by both a lower and / or an upper limit, given that a range is defined by the selection of a lower limit and / or an upper limit. Such ranges defined by a lower and / or an upper limit can either include or exclude the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range not explicitly recited, and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individual disclosed point or singular number can itself be a lower limit or an upper limit combined with any other point or singular number or with other lower limits or upper limits to form a range not explicitly recited.

[0018] If not specifically stated, all embodiments of the present application, as well as optional embodiments, can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0019] The present application provides a method for preparing pentandiol from furfural, which comprises: contacting a reactant furfural and hydrogen in the presence of a non-noble metal catalyst and isopropyl alcohol to perform a hydrogenation reaction, forming a reaction product containing pentandiol (PeD).

[0020] In the present application, the non-noble metal catalyst is a cobalt-copper binary catalyst (abbreviated as "CoCu") and / or a cobalt-zirconium-copper ternary catalyst (abbreviated as "CoZrCu"), and the non-noble metal catalyst is prepared by a coprecipitation method comprising the following steps (1) and (2):

[0021] (1) precipitating and aging a metal source comprising a cobalt salt, a copper salt and an optional zirconium salt, and a precipitant comprising NaOH and Na2CO3 in water to obtain a solid-liquid product;

[0022] (2) performing solid-liquid separation on the solid-liquid product, and then sequentially washing, drying and calcining the obtained solid.

[0023] In some embodiments, in the cobalt-copper binary catalyst, the molar ratio of Co to Cu is (3-8):(1-2), for example, 3:1, 4:2, 5:2, 6:2, etc.

[0024] In some embodiments, in the cobalt-zirconium-copper ternary catalyst, the molar ratio of Co, Zr and Cu is (4-7):(5-9):(1-3), for example, 4:6:2, 4:7:2, 5:6:2, 5:7:1, 5:7:2, 5:7:3, 6:7:2, 5:8:2, 4:9:2, 6:9:2, 6:8:1, 7:8:2, etc.

[0025] In order to further improve the yield of pentanediol, preferably, the non-precious metal catalyst is a cobalt-zirconium-copper ternary catalyst. More preferably, the molar ratio of the elements Co, Zr, and Cu in the cobalt-zirconium-copper ternary catalyst is preferably (4-5): (6-8): (1-3).

[0026] In the present invention, the metal source includes a cobalt salt, a copper source, and optionally a zirconium salt. The relative molar ratio of the various metal elements in the catalyst can be determined based on the molar feed amounts of the different metal sources. The present invention does not particularly limit the metal salts, as long as they are soluble in water and form a precipitate with the precipitant. Specifically, when the non-precious metal catalyst is a binary catalyst CoCu, the metal source can be a cobalt salt and a copper salt. When the non-precious metal catalyst is a ternary catalyst CoZrCu, the metal source can be a cobalt source, a copper source, and a zirconium salt.

[0027] According to some embodiments, the cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate; the copper salt is selected from at least one of copper nitrate, copper chloride, and copper sulfate; and the zirconium salt is selected from at least one of zirconium nitrate and zirconium oxychloride. Furthermore, the term "metal salt" should be broadly understood to encompass both anhydrous metal salts and various metal salt hydrates. For example, the cobalt nitrate can be either anhydrous cobalt nitrate (Co(NO)) or a cobalt nitrate hydrate (e.g., Co(NO3)2·6H2O). As specific examples, the copper salt can be one or more of Cu(NO3)2, Cu(NO3)2·3H2O, and Cu(NO3)2·6H2O, and the zirconium salt can be Zr(NO3)2 and / or Zr(NO3)2·5H2O.

[0028] In the present invention, the precipitant includes NaOH and Na2CO3. Compared to alkaline precipitants such as urea, the combination of NaOH and Na2CO3 is more conducive to improving the yield of the target product. In some preferred embodiments, the mass ratio of NaOH to Na2CO3 is 1:(5-7), for example, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, etc.

[0029] As some specific examples, step (1) further comprises the following operations of preparing the reaction mixture:

[0030] (1-1) dissolving a metal source in water to obtain a metal salt aqueous solution; the concentration of the metal salt aqueous solution can be 0.5-15 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L, 7 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, etc.; the dissolving can be performed under ultrasonic condition, and the ultrasonic time can be 10-50 min, for example, 15 min, 20 min, 25 min, 30 min, 40 min, 45 min, 50 min, etc.

[0031] (1-2) under stirring, adding dropwise an aqueous solution of a precipitant to the metal salt aqueous solution to obtain a reaction mixture, wherein the amount of the aqueous solution of the precipitant is such that the pH of the reaction mixture is 9-11, for example, 9.5, 10, 10.5, 11, etc.; the concentration of the aqueous solution of the precipitant can be 1-5 wt%, for example, 1 wt%, 2 wt%, 2.2 wt%, 2.6 wt%, 3 wt%, 5 wt%, etc.

[0032] In the present application, the metal source and the precipitant form corresponding hydroxide and carbonate precipitates in water through a precipitation reaction. As some embodiments, the temperature of the precipitation reaction can be room temperature (15-40℃), for example, 15℃, 18℃, 20℃, 25℃, 30℃, 40℃, etc.; the reaction time can be 1-6 h, for example, 1 h, 2 h, 3 h, 3.5 h, 4 h, 5 h, etc.

[0033] In the present application, the aging treatment can make the precipitated crystal particles more uniform and stable. Preferably, the temperature of the aging treatment is 70-85℃, for example, 70℃, 80℃, 85℃, etc., and the aging time is 8-15 h, for example, 8 h, 10 h, 11 h, 12 h, 14 h, etc.

[0034] The solid-liquid separation in step (2) is not particularly limited in the present application, as long as the solid (catalyst precursor) can be separated therefrom, for example, but not limited to, the solid-liquid separation is performed by suction filtration. The washing aims to remove impurities on the catalyst precursor, for example, water washing can be performed until the obtained water washing liquid is neutral.

[0035] In step (2), water on the catalyst precursor can be removed by drying, which can be performed in an oven, for example. According to some embodiments, the drying can be performed at a temperature of 90-140°C, such as 90°C, 95°C, 100°C, 110°C, 130°C, etc., and for a time period of 9-16h, such as 9h, 10h, 11h, 12h, 15h, 16h, etc.

[0036] In step (2), the catalyst precursor can be converted into metal oxides by the calcination. The calcination can be performed in an oxygen-containing atmosphere, such as oxygen or air. According to some embodiments, the calcination is performed in air at a temperature of 500-700°C, such as 500°C, 550°C, 600°C, 620°C, 650°C, 700°C, etc., and for a time period of 2-8h, such as 3h, 4h, 5h, 7h, 8h, etc. In addition, the calcination can be performed in a muffle furnace.

[0037] As some specific embodiments, step (2) comprises the following operations:

[0038] (2-1) filtering the solid-liquid product, and washing and drying the obtained solid (i.e., filter cake);

[0039] (2-2) crushing (e.g., grinding) and sieving the product obtained in step (2-1) to obtain undersize, and calcining the undersize.

[0040] In some embodiments, the non-noble metal catalyst has a particle size of no more than 100 mesh.

[0041] In the present application, the non-noble metal catalyst formed by calcination generally exists in the form of metal oxides in different valence states (as shown in Figure 1 which can be directly used in the furfural hydrogenation reaction. In the reaction, hydrogen not only serves as a reactant, but also as a reducing gas to reduce the metal oxides in the catalyst to improve the catalyst activity.

[0042] In the present application, the furfural hydrogenation reaction can be performed in a high-pressure reaction kettle under stirring. The temperature of the hydrogenation reaction can be 130-180°C, such as 130°C, 140°C, 150°C, 155°C, 160°C, 170°C, 180°C, and preferably 140-170°C to effectively improve the yield of pentanediol.

[0043] In the present application, the hydrogen pressure can be 2-10 MPa, for example, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 8 MPa, 10 MPa, etc., preferably 2-6 MPa; the reaction time can be 3-10 h, for example, 2 h, 3 h, 5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 9 h, 10 h, etc., preferably 4-8 h; the stirring speed can be 300-700 rpm, for example, 350 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, etc.

[0044] In the present application, the amount of the non-noble metal catalyst can be selected according to the amount of furfural. As some embodiments, the mass ratio of the non-noble metal catalyst to furfural can be (0.5-3) : 1, for example, 0.8: 1, 1: 1, 1.5: 1, 1.7: 1, 2: 1, 2.2: 1, 2.3: 1, 2.5: 1, 2.8: 1, etc., preferably (1.5-2.5) : 1.

[0045] The inventors of the present application found in the research that, compared with other fatty alcohols, the furfural hydrogenation using the non-noble metal catalyst of the present application in isopropyl alcohol as the reaction medium can effectively improve the reaction speed and the selectivity to pentandiol in the product. According to the present application, the mass ratio of furfural to isopropyl alcohol can be 1: (100-200), for example, 1: 120, 1: 128, 1: 130, 1: 135, 1: 150, 1: 180, etc.

[0046] In the present application, the reaction product generated by the furfural hydrogenation reaction mainly includes pentandiol (Ped), wherein the pentandiol mainly includes 1, 2-pentandiol and 1, 5-pentandiol. In addition to the target product pentandiol, the reaction product can also include other by-products, which can be one or more of, for example, furfuryl alcohol (FOL), tetrahydrofurfuryl alcohol (THFOL), 2-methyl furan, 1-pentanol, 2-pentanol, etc. Preferably, the mass content of pentandiol in the reaction product is not less than 50%.

[0047] In the present application, after the hydrogenation reaction is completed, preferably, the method further comprises: centrifuging the reaction system after the hydrogenation reaction to recover the non-noble metal catalyst therein. In addition, in the supernatant obtained by centrifugation, in addition to pentandiol and the reaction medium isopropyl alcohol, it also contains the above-mentioned other by-products.

[0048] The following describes the embodiments of the present application. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0049] The comparative preparation example and the preparation example are used to illustrate the non-noble metal catalysts employed in the comparative examples and the examples and the method for preparing the same. Unless otherwise specified, the mixed aqueous solution of NaOH and Na2CO3 is prepared as follows: 0.4 g of NaOH is added to 64 mL of deionized water to prepare solution a, 2.4 g of Na2CO3 is added to 40 mL of deionized water to prepare solution b, and then the solution a and the solution b are mixed uniformly to prepare the mixed aqueous solution of NaOH and Na2CO3, wherein the total concentration of NaOH and Na2CO3 is 2.6 wt%, and the mass ratio of NaOH to Na2CO3 is 1:6.

[0050] Comparative Preparation Example 1

[0051] The method for preparing the cobalt catalyst is as follows.

[0052] At room temperature, 0.5 mol of Co(NO3)2·6H2O is added to 200 mL of deionized water and is ultrasonically treated for 20 min to dissolve the cobalt salt in the deionized water to obtain a cobalt salt aqueous solution. Under magnetic stirring, the mixed aqueous solution of NaOH and Na2CO3 is slowly added dropwise into the cobalt salt aqueous solution until the pH of the obtained initial reaction liquid is 10, and the reaction is continuously stirred at room temperature for 3 h to form a precipitate. The precipitate system is transferred into a blast oven and is aged at 80 °C for 12 h, and then is suction filtered, and the obtained solid is washed with ionized water to neutral to obtain a catalyst precursor.

[0053] The catalyst precursor is dried in an oven at 80 °C for 12 h, and then is cooled to room temperature, is ground, is passed through a 100-mesh sieve, and the obtained undersize is calcined at 600 °C in an air atmosphere for 5 h to prepare a cobalt catalyst, which is denoted as CoO x .

[0054] Comparative Preparation Example 2

[0055] The zirconium catalyst is prepared according to the method of the comparative preparation example 1, except that the cobalt salt aqueous solution is replaced by a zirconium salt aqueous solution, specifically, 0.7 mol of Zr(NO3)4·5H2O is added to 500 mL of deionized water and is dissolved by ultrasonic treatment to form a zirconium salt aqueous solution. The prepared zirconium catalyst is denoted as ZrO x .

[0056] Comparative Preparation Example 3

[0057] The copper catalyst is prepared according to the method of the comparative preparation example 1, except that the cobalt salt aqueous solution is replaced by a copper salt aqueous solution, specifically, 0.2 mol of Cu(NO3)2·3H2O is added to 200 mL of deionized water and is dissolved by ultrasonic treatment to form a copper salt aqueous solution. The prepared copper catalyst is denoted as CuO x .

[0058] Comparative Preparation Example 4

[0059] A cobalt-zirconium binary catalyst was prepared according to the method of Comparative Preparation Example 1, except that a mixed aqueous solution of cobalt and zirconium salts was used instead of the aqueous cobalt salt solution, specifically, 0.5 mol of Co(N03)2-6H20 and 0.7 mol of Zr(N03)4-5H20 were added to 500 mL of deionized water and dissolved using ultrasonic treatment to form the mixed aqueous solution of cobalt and zirconium salts. The prepared catalyst was designated as CoZr(5:7).

[0060] Comparative Preparation Example 5

[0061] A zirconium-copper binary catalyst was prepared according to the method of Comparative Preparation Example 1, except that a mixed aqueous solution of zirconium and copper salts was used instead of the aqueous cobalt salt solution, specifically, 0.7 mol of Zr(N03)4-5H20 and 0.2 mol of Cu(N03)2-3H20 were added to 500 mL of deionized water and dissolved using ultrasonic treatment to form the mixed aqueous solution of cobalt and copper salts. The prepared catalyst was designated as ZrCu(7:2).

[0062] Preparation Example 1

[0063] A cobalt-copper binary catalyst was prepared according to the method of Comparative Preparation Example 1, except that a mixed aqueous solution of cobalt and copper salts was used instead of the aqueous cobalt salt solution, specifically, 0.5 mol of Co(N03)2-6H20 and 0.2 mol of Cu(N03)2-3H20 were added to 500 mL of deionized water and dissolved using ultrasonic treatment to form the mixed aqueous solution of cobalt and copper salts. The prepared catalyst was designated as CoCu(5:2).

[0064] Preparation Example 2

[0065] At room temperature, 0.5 mol of Co(N03)2-6H20, 0.7 mol of Zr(N03)4-5H20 and 0.2 mol of Cu(N03)2-3H20 were added to 500 mL of deionized water and ultrasonically treated for 40 min to obtain an aqueous metal salt solution.

[0066] Under magnetic stirring, a mixed aqueous solution of NaOH and Na2C03 was slowly added dropwise to the aqueous metal salt solution until the pH of the resulting initial reaction liquid reached 10, and the reaction was continuously stirred for 3 h to form a precipitate. The precipitate system was transferred to a blast oven and aged at 80 °C for 12 h, followed by suction filtration, and the obtained solid was washed with ionized water until neutral to obtain a catalyst precursor.

[0067] The catalyst precursor was dried in an oven at 80°C for 12 h, then cooled to room temperature, ground, passed through a 100 mesh sieve, and the undersize was calcined at 600°C in an air atmosphere for 5 h to produce a cobalt-zirconium-copper ternary catalyst, denoted as CoZrCu(5:7:2).

[0068] Preparation Examples 3-8

[0069] A cobalt-zirconium-copper ternary catalyst was prepared according to the method of Preparation Example 2, except that the molar amounts of Co(NO3)2·6H2O, Zr(NO3)4·5H2O and Cu(NO3)2·3H2O were adjusted as shown in Table 1 to obtain ternary catalysts with different molar ratios of the three metal components.

[0070] Table 1

[0071]

[0072]

[0073] Note: In the catalyst number, the number in the parentheses represents the molar ratio of the metal elements.

[0074] The following examples are used to illustrate the method for preparing pentanediol from furfural according to the present application.

[0075] The product composition in the supernatant was analyzed by gas chromatography (instrument model Shimadzu GC-2014C, chromatographic column model WondaCap5 (30.0 m x 0.25 μm x 0.25 mm), wherein the injection port temperature was 250°C, the initial column temperature was 60°C, the temperature rise rate was 20°C / min, the final column temperature was 245°C, and the detector temperature was 280°C), and the furfural conversion rate and the yield of each product were calculated according to the following formula.

[0076]

[0077] Total pentanediol yield (%) = 1,2-pentanediol yield (%) + 1,5-pentanediol yield (%)

[0078] Comparative Example 1

[0079] 0.175 g of furfural, 0.4 g of the catalyst CoO x and 23.6 g of isopropanol were charged into a high-pressure reaction kettle, the reaction kettle was sealed, the air in the kettle was replaced with hydrogen, 3 MPa of H2was injected after exhausting, the temperature was raised to 140°C under stirring at a stirring rate of 550 rpm, and the closed reaction was carried out at this temperature for 6 h, then cooled to room temperature, the obtained product was centrifuged to obtain a supernatant containing the reaction product. The composition of the supernatant was analyzed by gas chromatography, and the conversion rate of the reactant and the yield of the product were calculated, and the test results are shown in Table 2.

[0080] Comparative Examples 2-5

[0081] The catalytic hydrogenation reaction of furfural was carried out according to the method of Comparative Example 1, except that the catalyst CoO x was replaced by the catalysts of Comparative Preparation Examples 2-5, respectively. The composition of the supernatant was analyzed by gas chromatography, and the conversion rate of the reactant and the yield of the product were calculated. The test results are shown in Table 2.

[0082] Examples 1-8

[0083] The catalytic hydrogenation reaction of furfural was carried out according to the method of Comparative Example 1, except that the catalyst CoO x was replaced by the catalysts of Preparation Examples 1-8, respectively. The composition of the supernatant was analyzed by gas chromatography, and the test results of the reaction are shown in Table 2.

[0084] Table 2

[0085]

[0086] Note: " / " indicates that the corresponding product is not detected by GC; "> 99" means that when the supernatant is analyzed by a gas chromatograph, almost no characteristic chromatographic peak of furfural is detected, and it is determined that the furfural in the reaction system is completely converted.

[0087] From the results in Table 2, when single-component metal cobalt (CoO x ) is used as the catalyst in Comparative Example 1, although the furfural is almost completely converted, the total yield of pentanediol is only 28.35%, the selectivity of the cobalt catalyst to the target products 1,2-pentanediol and 1,5-pentanediol is low, and the byproduct tetrahydrofurfuryl alcohol is formed with a yield as high as 41.11%. In Comparative Examples 2-3, single-component metal zirconium (ZrO x ) and copper (CuO x ) are used as the catalysts, and the hydrogenation reaction of furfural is carried out, but pentanediol cannot be successfully synthesized. In Comparative Examples 4-5, binary metals CoZr and ZrCu are used as the catalysts, and the hydrogenation reaction of furfural is carried out, but pentanediol cannot be successfully synthesized. The results of Examples 1-8 show that when CoCu binary catalysts and CoZrCu ternary catalysts are used to catalyze the hydrogenation reaction of furfural, the selectivity to 1,2-pentanediol and 1,5-pentanediol is higher while ensuring a high conversion rate of furfural, and the total yield of pentanediol is not less than 44%.

[0088] Compared with the results of Example 1 and Examples 2-8, it can be seen that, compared with the binary catalyst CoCu (5:2), the ternary catalyst CoZrCu can further improve the total yield of pentanediol in the catalytic hydrogenation reaction of furfural. In addition, according to Examples 2-8, when the molar ratio of metal elements Co, Zr and Cu in the ternary catalyst CoZrCu is 5:7:2, a higher yield of pentanediol can be obtained, and the total yield of pentanediol can reach 66.97%.

[0089] Example 9

[0090] 0.175g of furfural, 0.4g of catalyst CoZrCu (5:7:2) and 23.6g of isopropanol were charged into a high-pressure reaction kettle, the reaction kettle was sealed, the air in the kettle was replaced with nitrogen, 3MPa of H2was injected after exhausting, the stirring speed was 550rpm, the temperature was raised to 150°C, and the reaction was carried out at the temperature for 6h, and then cooled to room temperature. The obtained product was centrifuged to obtain a supernatant containing reaction products. The composition of the supernatant was analyzed by gas chromatography, and the test results of the reaction are shown in Table 3.

[0091] Examples 10-11

[0092] According to the method of Example 9, furfural was catalytically hydrogenated, except that the reaction temperature was adjusted to 160°C and 170°C respectively. The composition of the supernatant was analyzed by gas chromatography, and the conversion rate of the reactants and the yield of the products were calculated, and the test results are shown in Table 3.

[0093] Table 3

[0094]

[0095] For comparison, the test results of Example 2 are also listed in Table 3. As can be seen from Table 3, when the temperature is not lower than 140°C, the total yield of pentanediol can be significantly improved, all of which are more than 51%. Among them, at 140°C, the conversion rate of furfural is 98.15%, and the total yield of pentanediol is 66.97%, which is the best.

[0096] Example 12

[0097] 0.175g of furfural, 0.4g of catalyst CoZrCu (5:7:2) and 23.6g of isopropanol were charged into a high-pressure reaction kettle, the reaction kettle was sealed, the air in the kettle was replaced with nitrogen, 3MPa of H2was injected after exhausting, the stirring speed was 550rpm, the temperature was raised to 140°C, and the reaction was carried out at the temperature for 4h, and then cooled to room temperature. The obtained product was centrifuged to obtain a supernatant containing reaction products. The composition of the supernatant was analyzed by gas chromatography, and the test results of the reaction are shown in Table 4.

[0098] Examples 13-15

[0099] Furfural was catalytically hydrogenated according to the method of Example 12, except that the reaction time was adjusted to 5 h, 7 h and 8 h, respectively. The supernatant was analyzed by gas chromatography, and the results of the reaction test are shown in Table 4.

[0100] Table 4

[0101]

[0102]

[0103] For comparison, the test results of Example 2 are also listed in Table 4. As shown in Table 4, when the reaction time is 4-8 h, the conversion rate of furfural is >97%, and the total yield of pentanediol is >51%.

[0104] Example 16

[0105] A high-pressure reaction kettle was charged with 0.175 g of furfural, 0.4 g of catalyst CoZrCu (5:7:2) and 23.6 g of isopropanol. After the kettle was sealed, the air in the kettle was replaced with hydrogen, and 2 MPa of H2was introduced after exhausting. The reaction was carried out at 140°C for 6 h under stirring at a speed of 550 rpm, and then the kettle was cooled to room temperature. The obtained product was separated by centrifugation to obtain a supernatant containing reaction products. The supernatant was analyzed by gas chromatography, and the results of the reaction test are shown in Table 5.

[0106] Examples 17-18

[0107] Furfural was catalytically hydrogenated according to the method of Example 16, except that the introduced H2pressure was adjusted to 4 MPa and 5 MPa, respectively. The supernatant was analyzed by gas chromatography, and the results of the reaction test are shown in Table 5.

[0108] Table 5

[0109]

[0110] For comparison, the test results of Example 2 are also listed in Table 5. As shown in Table 5, when the hydrogen pressure is controlled to be 2-5 MPa, a higher total yield of pentanediol can be obtained, and the yield is not less than 58%.

[0111] Example 19

[0112] A high-pressure reaction kettle was charged with 0.175 g of furfural, 0.3 g of CoZrCu (5:7:2) and 23.6 g of isopropanol. After the kettle was sealed, the air in the kettle was replaced with hydrogen, and 3 MPa of H2was injected after the exhaust. The reaction was carried out at 550 rpm and 140°C for 6 h. The product was separated by centrifugation to obtain a supernatant containing the reaction product. The composition of the supernatant was analyzed by gas chromatography, and the test results are shown in Table 5.

[0113] Example 20

[0114] The method of Example 19 was used for the catalytic hydrogenation reaction of furfural, except that the amount of catalyst CoZrCu (5:7:2) was adjusted to 0.5 g. The composition of the supernatant was analyzed by gas chromatography, and the test results are shown in Table 6.

[0115] Table 6

[0116]

[0117] For comparison, the test results of Example 2 are also shown in Table 6. As can be seen from Table 6, when the amount of catalyst is 0.3-0.5 g, a higher total yield of pentanediol can be obtained, and the yield is not less than 40%.

[0118] Comparative Example 6

[0119] The method of Example 2 was used for the catalytic hydrogenation reaction of furfural, except that isopropanol was replaced with ethanol. The composition of the supernatant was analyzed by gas chromatography, and the test results are shown in Table 7.

[0120] Table 7

[0121]

[0122] Test Example

[0123] The above-prepared catalysts were characterized as follows.

[0124] 1. XRD Test

[0125] The catalysts were subjected to XRD test using a MiniFlex 600 X-ray diffractometer of Japan Rigaku Co. The catalysts without Co were measured under standard mode setting, and the catalysts containing Co metal were measured under fluorescence X-ray reduction mode. Cu-Kα was used as the ray source, and the working voltage and working current were 40 kV and 30 mA, respectively. The step setting was 0.02, the scanning range 2θ was 10-80°, and the scanning speed was 10° / min.

[0126] 2. Scanning Electron Microscope Test

[0127] The surface morphology of the catalyst was observed by a Regulus 8100 high-resolution cold field emission scanning electron microscope of Hitachi. The micro-area composition of the catalyst sample was analyzed by an energy dispersive spectrometer (EDS), and a mapping graph of elements was obtained.

[0128] 3. Transmission electron microscope test

[0129] A TEM graph of the catalyst was obtained by using a Thermofisher Scientific Talos F200X G2 transmission electron microscope of the United States.

[0130] The results are shown in Figures 1-3 .

[0131] Figure 1 For comparison, the XRD comparison graphs of the cobalt catalyst (CoO x ), the zirconium catalyst (ZrO x ), the copper catalyst (CuO x ), the binary catalysts CoZr (5:7), CoCu (5:2), ZrCo (7:2) and CoZrCu (5:7:2) of preparation examples 1-5 are shown in Figure 1 , the characteristic peaks of the CoO x sample at 36.8°, 31.3° and 44.8° are completely matched with the standard card of Co3O4, confirming that it is a pure spinel phase; the double peaks of the CuO x sample at 35.5° and 38.7° are consistent with the standard peak position of CuO monoclinic phase; the main peak of the ZrO x sample is at 30.2°, although there is a low-angle shift compared with the main peak (31.5°) of the standard card of ZrO 1.99 , it is still attributed to the monoclinic phase ZrO (PDF #80-2155), and it can be seen that the diffraction peaks of the three single metal catalysts correspond to the diffraction peaks in the standard cards of Co3O4 (PDF #43-1003), ZrO 1.99 (PDF #80-2155) and CuO (PDF #48-1548). No new phase is generated or the lattice is significantly distorted in the binary catalysts CoCu (5:2), CoZr (5:7) and ZrCu (7:2); in the ternary catalyst CoZrCu (5:7:2), the characteristic peak of Co3O4 disappears, and the main peak of ZrO2 shifts to 29.8° compared with 30.2° of the single metal ZrO X , proving that Co / Cu atoms are incorporated into the ZrO2 lattice to form a defective solid solution; at the same time, Co-O-Zr acid sites and Cu + / Cu 2+ redox sites are constructed, thereby significantly improving the ring-opening reaction of furan and the selectivity of FAL to PeD.

[0132] Figure 2 The scanning electron microscope (SEM) image of the catalyst CoZrCu (5:7:2) of Preparation Example 2 shows that CoZrCu (5:7:2) exhibits a uniform nanoparticle assembly structure. It is speculated that the confinement effect of CuO promotes the high dispersion of the active components on the surface of ZrO 1.99 EDS mapping shows that the Cu element of CoZrCu (5:7:2) exhibits island-like aggregation characteristics (possibly related to the reduction of the migration energy barrier of CuO during calcination). The uniform distribution of Co and Zr elements in the CoZrCu (5:7:2) catalyst significantly increases the interface contact area of the catalyst. This structural feature is likely to be an important reason for the excellent catalytic performance. 2+

[0133] Figure 3 The transmission electron microscope (TEM) image of the catalyst CoZrCu (5:7:2) of Preparation Example 2 shows that the CoZrCu (5:7:2) catalyst is composed of densely packed spherical or ellipsoidal nanoparticles. According to the crystal lattice fringes of the HR-TEM image, the crystal composition of the catalyst is good, and a crystal face spacing of 0.148 nm is observed, which corresponds to the (222) crystal face spacing of ZrO2 (PDF #80-2155). In addition, the characteristic crystal lattices of 0.126 nm (CuO (22-2)) and 0.285 nm (Co3O4 (220)) are consistent with the XRD diffraction peaks (2θ = 75.2° and 31.3°), confirming that it is a Co3O4-ZrO 1.99 -CuO multiphase composite system. Element distribution analysis (Mapping) shows that the three components of Co, Zr, and Cu exhibit uniform dispersion at the nanoscale, which is consistent with the SEM-EDS results. This highly dispersed metal-oxide interface structure effectively improves the accessibility of active sites. The synergistic effect of the micro-morphology and components together explains the excellent performance of the catalyst in the FAL hydrogenation reaction.

[0134] Finally, it should be noted that the above preparation examples are used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing preparation examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing preparation examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the preparation examples of the present application, and they should be covered in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in each preparation example can be combined in any way as long as there is no structural conflict. The present application is not limited to the specific preparation examples disclosed herein, but includes all technical solutions falling within the scope of the claims.​

Claims

1. A method for preparing pentanediol from furfural, characterized in that: The method comprises: contacting furfural with hydrogen in the presence of a non-noble metal catalyst and isopropyl alcohol to carry out a hydrogenation reaction to form a reaction product containing pentanediol; wherein, The non-precious metal catalyst is a cobalt-copper binary catalyst and / or a cobalt-zirconium-copper ternary catalyst, and the non-precious metal catalyst is prepared by a method comprising the following steps: (1) subjecting a metal source including a cobalt salt, a copper salt, and optionally a zirconium salt to a precipitation reaction with a precipitant including NaOH and Na2CO3 in water and aging the reaction to obtain a solid-liquid product; (2) subjecting the solid-liquid products to solid-liquid separation, and then washing, drying and calcining the obtained solid.

2. The method according to claim 1, characterized in that In the cobalt-copper binary catalyst, the molar ratio of the elements Co and Cu is (3-8): (1-2), and / or In the cobalt-zirconium-copper ternary catalyst, the molar ratio of Co, Zr and Cu is (4-7): (5-9): (1-3).

3. The method according to claim 1, characterized in that The non-precious metal catalyst is a cobalt-zirconium-copper ternary catalyst.

4. The method according to any one of claims 1 to 3, characterized in that The cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride and cobalt sulfate; The copper salt is selected from at least one of copper nitrate, copper chloride and copper sulfate; The zirconium salt is selected from zirconium nitrate and / or zirconium oxychloride.

5. The method according to any one of claims 1 to 4, characterized in that The mass ratio of NaOH to Na2CO3 is 1:(5-7); Preferably, step (1) further comprises the following steps to obtain a reaction mixture: (1-1) dissolving a metal source in water to obtain a metal salt solution; (1-2) Adding a 1-5 wt% aqueous solution of a precipitant to the metal salt solution under stirring to obtain a reaction mixture; wherein the amount of the aqueous solution of the precipitant is such that the pH of the reaction mixture is 9-11.

6. The method according to any one of claims 1 to 5, characterized in that The precipitation reaction temperature is 15 to 40° C. and the time is 1 to 6 hours; Preferably, the aging temperature is 70-85°C and the aging time is 8-15h; Preferably, the drying temperature is 90-140°C and the drying time is 9-16 hours; Preferably, the calcination is carried out in an air atmosphere, the calcination temperature is 500-700° C., and the calcination time is 2-8 hours.

7. The method according to any one of claims 1 to 6, characterized in that Step (2) includes the following operations: (2-1) filtering the solid-liquid product, washing the obtained filter cake with water, and drying; (2-2) The product obtained in step (2-1) is crushed, sieved and calcined.

8. The method according to any one of claims 1 to 7, characterized in that The hydrogenation reaction is carried out in a high-pressure reactor under stirring conditions. The temperature of the hydrogenation reaction is 130-180° C., the pressure of the introduced hydrogen is 2-10 MPa, the reaction time is 3-10 h, and the stirring speed is 300-700 rpm.

9. The method according to any one of claims 1 to 8, characterized in that The mass ratio of the non-precious metal catalyst to furfural is (0.5-3):1; Preferably, the mass ratio of furfural to isopropyl alcohol is 1:(100-200).

10. The method according to any one of claims 1 to 9, characterized in that The method further comprises: centrifuging the reaction system after the hydrogenation reaction is completed to recover the non-precious metal catalyst.

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