CN113773284A - Method for preparing 2, 5-dihydroxymethyl tetrahydrofuran by hydrogenation of 5-hydroxymethylfurfural - Google Patents

Abstract

The invention discloses a method and application for preparing 2,5-dimethyloltetrahydrofuran (BHMTHF) by catalytic hydrogenation of 5-hydroxymethylfurfural (5-HMF). A supported catalyst is used, and the first active component and the second component are respectively obtained from corresponding non-precious metal salt solutions and selected from Ni(NO ₃ ) ₂ ·6H ₂ O and Co(NO ₃ ) ₂ ·6H ₂ O. The bimetallic catalyst was prepared by a coprecipitation method with a typical acidic oxide gas-phase SiO ₂ as a carrier, and the loading amount of the two active components was (4/1～1/1). The catalyst is simple in preparation method, low in price and cyclical, the catalytic reaction system is green, the reaction substrate is reproducible, the reaction conditions are mild, the input cost is low, and the catalyst has broad prospects for industrial application.

Description

A kind of method for preparing 2,5-dimethylol tetrahydrofuran by hydrogenation of 5-hydroxymethyl furfural

technical field

The invention belongs to the technical field of fine chemicals, and in particular relates to a preparation method of a non-precious bimetal supported catalyst and a method for preparing 2,5-dimethyloltetrahydrofuran by hydrogenation of 5-hydroxymethylfurfural.

Background technique

At present, 5-hydroxymethylfurfural (5-HMF) has attracted extensive attention as an important multifunctional platform compound. Usually it is obtained by dehydration of sugars derived from biomass under the action of acid catalysis. 5-HMF can be converted into high value-added chemical 2,5-dimethyloltetrahydrofuran (BHMTHF) after complete hydrogenation. BHMTH can be used as a degradable, low toxicity, high stability green solvent. In addition, it can also be used as a substrate for further hydrogenation into high value-added linear polyols. For example, 1,5 pentanediol and 1,6 hexanediol, etc. (Keiichi Tomishige, ACS Catal. 2014, 4, 2718-2726). This also shows once again that the preparation of BHMTH by 5-HMF is of great significance.

Cu催化5-HMF制备2，5-二羟甲基呋喃(DHMF)，再以

N催化DHMF制得BHMTH(Klaus Hellgardt,RSCAdv.,2017,7,31401)。使用两步法制备BHMTH不但反应过程复杂，而且增加了成本。因此，直接转换化5-HMF制备BHMTH引起了广泛关注。然而，在水相中，且使用非贵金属催化剂的相关研究还处于起步阶段。因此开发高效廉价、环境友好的非贵金属催化剂用于催化转化HMF制备BHMTHF是一项紧迫的挑战。Usually, BHMTH is prepared by a two-step method: first, under the action of a solid acid catalyst, biomass derivatives such as sugars are dehydrated to synthesize 5-HMF (Yunchao Feng, Green Chemistry 2020, 22(18), 5984-5988); then 5 -HMF is converted to BHMTH over a heterogeneous metal catalyst (Keiichi Tomishige, Catalysis Communications. 12 (2010) 154-156). Furthermore, first

Cu-catalyzed 5-HMF to prepare 2,5-dimethylolfuran (DHMF), and then

N catalyzes DHMF to produce BHMTH (Klaus Hellgardt, RSC Adv., 2017, 7, 31401). Using the two-step method to prepare BHMTH not only complicated the reaction process, but also increased the cost. Therefore, the direct conversion of 5-HMF to prepare BHMTH has attracted extensive attention. However, in the aqueous phase, related research using non-precious metal catalysts is still in its infancy. Therefore, it is an urgent challenge to develop efficient, inexpensive and environmentally friendly non-noble metal catalysts for catalytic conversion of HMF to BHMTHF.

SUMMARY OF THE INVENTION

In view of the above background, the present invention proposes to use cheap non-precious bimetallic nickel and cobalt as active components, acidic oxide gas _- phase _SiO2 as carrier, and _Na2CO3 as precipitant to prepare bimetallic catalyst by co-precipitation method. A high value-added fine chemical BHMTHF was synthesized by catalytic hydrogenation of 5-HMF in water in a one-pot method. The catalyst system uses water as a solvent, is greener and more economical than an organic solvent system, uses a non-precious metal as an active component, is easier to industrially produce than a precious metal catalyst, and has a simple catalyst preparation method. The schematic diagram of the reaction process is shown in Figure 1. This method provides a simple, low-cost, high-efficiency, environment-friendly and industrial-friendly production method for the conversion of 5-HMF into BHMTHF.

The specific steps of the non-precious bimetallic supported catalyst of the present invention are as follows: firstly adding the metal salt aqueous solution containing active components into the carrier to form a precursor mixture, and then adding the pre-prepared Na ₂ CO ₃ and NaOH solutions dropwise Add to the precursor mixture and keep stirring until moderately strong alkaline (eg pH=8-12, preferably 10), and continue to age for 10h. Wash the aged mixture to neutrality with deionized water. It was then placed in an oven at 100 °C for 12 h. It is then calcined at 400-600° C., preferably 500° C. for 3-5 hours, and reduced in a hydrogen atmosphere before use.

The invention also provides the application of the non-precious bimetallic supported catalyst in the hydrogenation reaction of 5-hydroxymethylfurfural, 3-hydroxymethylcyclopentanol and 3-hydroxymethylcyclopentanone as substrates.

The present invention also provides a method for preparing BHMTHF by catalytic hydrogenation of 5-HMF, comprising the following steps: adding 5-HMF, a solvent and a non-precious bimetallic supported catalyst into an intermittent closed high-pressure reaction kettle, and carrying out catalytic selectivity under stirring Hydrogenation reaction, preferably, the amount of the non-precious bimetallic supported catalyst is 1/10 to 1/2 of the mass of 5-HMF, preferably 3/10, the initial hydrogen pressure is 1-6MPa, and the reaction temperature is 90 ~120℃, the reaction time is 1 ~ 5h.

The specific steps of 5-HMF aqueous hydrogenation are as follows: weigh 0.2g of 5-HMF, 10mL of water and 0.06g of catalyst and put it into a 40mL reaction kettle. Replace the air in the kettle with nitrogen three to four times, then fill with hydrogen until the initial pressure is 3MPa, turn on the stirring device at about 400r/min, heat it to 110 °C for 4 hours and then cool down, the product is separated by a centrifuge, using high performance liquid Chromatography (HPLC, Thermo Scientific) was used for quantitative analysis.

The non-precious bimetallic catalyst provided by the invention is used for 5-HMF aqueous phase hydrogenation to prepare BHMTHF, and using deionized water as a solvent can not only reduce the production cost, but also be beneficial to environmental protection. The equipment requirements are low, the operation is simple, the raw material 5-HMF is renewable, and the product selectivity is high, and it has a broad market application prospect. Compared with the noble metal catalyst, the catalyst used in the present invention has the advantages of low price and the like. The catalyst does not need to be regenerated, it can be recycled after only drying, and the yield remains basically unchanged, which has obvious advantages.

Description of drawings

Fig. 1. Reaction schematic diagram of the non-precious bimetallic catalyst Ni ₁ /Co ₃ -SiO ₂ catalyzing the aqueous hydrogenation of 5-HMF to prepare BHMTHF.

Fig. 2 is an effect diagram of separating the metal catalyst of the present invention by a magnet after the reaction is completed.

Fig. 3 When the reaction temperature is 110°C, the reaction pressure is 3MPa, the reaction material-to-liquid ratio is 0.2g/10ml, the reaction time is 4h, and the stirring speed is 400r/min, the liquid phase of the BHMTHF product prepared by the aqueous hydrogenation of 5-HMF Spectrum.

Detailed ways

The present invention will be further described with reference to the implementation examples. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products. The specific implementation cases are as follows:

Example 1

Preparation of catalyst: Weigh 0.003mol of Ni( _NO3 ) _2.6H2O and _0.009mol of Co( _{NO3 ) 2.6H2O} in 150ml of deionized water, and then add 1g of _CeO2 to obtain the precursor. Then weigh 3 g of Na ₂ CO ₃ and 1 g of NaOH in 10 ml of deionized water. Add dropwise to the precursor mixture and keep stirring. Stir until pH=10, and continue to age for 10h. Wash the aged mixture to neutrality with deionized water. It was then placed in an oven at 100 °C for 12 h. After calcining at 500°C for 4 hours, and reducing in a hydrogen atmosphere before use, the bimetallic catalyst can be obtained.

Preparation of BHMTHF: Weigh 0.2g 5-HMF, 10mL water and 0.06g catalyst (Ni _x -Co _y /CeO ₂ , where x=1, y=3, CeO ₂ is the carrier) and put it into a 40mL reaction kettle . Replace the air in the kettle with nitrogen three to four times, then fill with hydrogen until the initial pressure is 3MPa, turn on the stirring device at about 400r/min, heat it to 110 °C for 4 hours and then cool down, the catalyst and the product are separated by a magnet, and the catalyst is recovered. , and its separation effect diagram is shown in Figure 2. The liquid product was qualitatively and quantitatively analyzed by high performance liquid chromatography (HPLC, Thermo Scientific). As a result, the conversion rate of 5-HMF was 99.7%, and the yield of BHMTHF was 14.7%.

Example 2

The preparation method of the catalyst is the same as that in Example 1, but the CeO ₂ is replaced with gas-phase SiO ₂ , and the reacted catalyst is recovered by a magnet for repeated circulation experiments.

The preparation method of BHMTHF is carried out with reference to the method in Example 1. The product was qualitatively and quantitatively analyzed by high performance liquid chromatography (HPLC, Thermo Scientific). The liquid chromatogram under this condition is shown in FIG. 3 . The peak at 22-24 min represents BHMTHF. As a result, the conversion rate of 5-HMF was 100%, and the yield of BHMTHF was 82.9%.

Example 3-5

The corresponding bimetallic metal catalyst was prepared according to the method of Example 2, wherein the atomic ratio of Co/Ni in Example 3 was 1/1 (that is, 0.003 mol of Ni(NO ₃ ) ₂ ·6H ₂ O and 0.003 mol of Ni(NO 3 ) 2 ·6H 2 O were weighed Co(NO ₃ ) ₂ ·6H ₂ O); the Co/Ni atomic ratio in Example 4 is 2/1 (that is, 0.003 mol of Ni(NO ₃ ) ₂ ·6H ₂ O and 0.006 mol of Co ( NO ₃ ) ₂ .6H ₂ O); the Co/Ni atomic ratio in Example 5 is 4/1 (ie 0.003 mol of Ni(NO ₃ ) ₂ .6H ₂ O and 0.012 mol of Co(NO ₃ ) ₂ . 6H ₂ O).

The catalyst prepared above was tested according to the method of Example 2, and the conversion rate and selectivity of the product obtained by the reaction were measured, and are listed in Table 1.

Table 1 Preparation of different types of catalysts and their effects on the conversion and selectivity of 5-HMF aqueous hydrogenation to prepare BHMTHF

Comprehensive examples 1 to 5 show that the carrier gas phase SiO ₂ is more suitable for the preparation of BHMTHF by the aqueous phase catalytic hydrogenation of 5-HMF than CeO ₂ . (3/1), BHMTHF reached the maximum yield. Continuing to increase the content of Co/Ni(4/1), the yield of BHMTHF decreases, so Co/Ni(3:1) is the best ratio for preparing the catalyst.

Examples 6-18

According to the reaction parameters in the following table, the corresponding bimetallic metal catalyst was prepared by the method of Example 2 for hydrogenation to prepare BHMTHF, in order to study its influence on the conversion rate and selectivity. The measurement results of the reaction products of each example are listed in Table 2.

Table 2 Effects of reaction parameters on the conversion and selectivity of 5-HMF aqueous hydrogenation to prepare BHMTHF ^[a]

Among them, ^[a] the ratio of catalyst dosage to substrate is 30/100, ^[b] the ratio of catalyst dosage to substrate is 10/100; ^[c] the ratio of catalyst dosage to substrate is 20/100; ^[d] the ratio of catalyst dosage to substrate is 20/100; The ratio of substrate is 40/100; ^[e] The ratio of catalyst amount to substrate is 5/10.

Combining with Examples 6 to 9, it can be seen that under the condition of constant substrate concentration, hydrogen pressure and reaction time (respectively: 0.2g/10ml, 3MPa, 4h), the temperature is continuously increased (from 90°C to 110°C) , the change trend of the selectivity of BHMTHF (increase from 20.7% to 82.9%, and then decrease to 57.0%), at 110 ℃, the yield of BHMTHF reaches the maximum 82.9%. Therefore, 110°C is the optimum reaction temperature.

Combining with Examples 10 to 13, it can be seen that under the condition of constant substrate concentration, reaction temperature and reaction time (respectively: 0.2g/10ml, 110°C, 4h), the reaction pressure (from 1MPa to 4MPa) is continuously increased, BHMTHF The change trend of the selectivity (increasing from 2.4% to 82.9%, and then decreasing to 72.4%) is similar to that of increasing temperature (from 90°C to 110°C). At 3MPa, the yield of BHMTHF reaches a maximum of 82.9%. Therefore, 3MPa is the optimum hydrogen pressure.

Combining with Examples 14 to 18, it can be seen that under the condition of constant substrate concentration, hydrogen pressure and reaction temperature (respectively: 0.2g/10ml, 3MPa, 110°C), increasing the reaction time (from 2h to 6h), the BHMTHF The selectivity trend (increased from 57.9% to 82.9%, and then decreased to 80.6%), at 4h, the yield of BHMTHF reached a maximum of 82.9%. Therefore, 4h is the best reaction time.

With reference to Examples 19 to 23, it can be seen that under the condition of constant substrate concentration, hydrogen pressure, reaction time and reaction temperature (respectively: 0.2g/10ml, 3MPa, 4h, 110°C), the amount of catalyst was continuously increased (from 10 /100 to 50/100), the change trend of the selectivity of BHMTHF (increase from 3.2% to 82.9%, and then decrease to 52.8%), when the ratio of catalyst dosage to substrate is 30/100, the yield of BHMTHF reaches the maximum 82.9%. Therefore, the optimal ratio of catalyst dosage/substrate is 30/100.

Example 24

The catalyst recovered in Example 2 was washed with deionized water for several times and then placed in a drying oven overnight, and then used for the second conversion reaction. The water-phase hydrogenation process and testing method are the same as those in Example 2. As a result, the conversion rate of 5-HMF was 100%, and the yield of BHMTHF was 79.5%.

After the above reaction is further completed, the catalyst is recovered, washed with deionized water for several times, placed in a drying box overnight, and then used for the third conversion reaction. The water-phase hydrogenation process and testing method are the same as those in Example 2. As a result, the conversion rate of 5-HMF was 100%, and the yield of BHMTHF was 77.6%.

Comprehensive examples 1 to 24 show that the present invention has developed a Ni ₁ -Co ₃ /SiO ₂ bimetallic catalytic system for the preparation of high value-added fine chemicals BHMTHF by 5-HMF aqueous hydrogenation. When the reaction temperature is 110 °C, the reaction time is 4 h, the hydrogen pressure is 3 MPa, the catalyst dosage is 30% of the substrate, and the stirring speed is 400 r/min, the loading of the two active components (Co/Ni) is 3/ At 1 hour, the conversion of 5-HMF was 100%, the selectivity of BHMTHF was 82.9%, and after two cycles, the yield of BHMTHF remained basically unchanged.

The specific examples of the present invention are only for the purpose of illustration, and the catalyst is suitable for the hydrogenation reaction of 5-hydroxymethylfurfural, 3-hydroxymethylcyclopentanol and 3-hydroxymethylcyclopentanone as substrates. applicable. It does not limit the protection scope of the present invention in any way, and those skilled in the art can make improvements or transformations according to the above description, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. The preparation method of the non-noble bimetal supported catalyst is characterized in that a catalyst carrier is two metal oxides CeO₂、SiO₂One of (1); the first active component of the catalyst is Ni; the second active component is Co; the preparation steps are as follows: respectively adding metal salt aqueous solution containing active components into a catalyst carrier to form precursor mixed solution, and then adding Na₂CO₃And NaOH in deionized water to form a precipitate, and slowly adding the precursorStirring the mixed solution until the pH value is 8-12, washing the aged mixed solution to be neutral by using deionized water, drying the mixed solution in an oven, and roasting for 3-6 h; further preferably, the reduction is carried out in a hydrogen atmosphere before use.

2. The production method according to claim 1, wherein the catalyst support is fumed silica.

3. The method according to claim 1, wherein the metal salt of the active components of the first and second active components of the catalyst is Ni (NO)₃)₂·6H₂O，NiCl₂·6H₂O and Co (NO)₃)₂·6H₂O，CoCl₂·6H₂O; preferably Ni (NO)₃)₂·6H₂O and Co (NO)₃)₂·6H₂O。

4. The method according to claim 1, wherein the Na is₂CO₃And NaOH in a weight ratio of 1-6: 1.

5. the method of claim 1, wherein the medium-strong alkalinity is a pH of 9 to 11, and aging is continued for 10 hours.

6. The preparation method according to claim 1, wherein the drying in the oven is drying in an oven at 100 ℃ for 10-15 h; the roasting is carried out at 400-600 ℃ for 3-6 h.

7. The method according to claim 1, wherein the reduction in the hydrogen atmosphere is carried out in a tubular furnace at 400-600 ℃ and through which hydrogen is introduced for 3-6h, preferably in a tubular furnace at 500 ℃ and through which hydrogen is introduced for 4 h.

8. The non-noble bimetallic supported catalyst prepared by the process for preparing a non-noble bimetallic supported catalyst according to any one of claims 1 to 7.

9. Use of the non-noble bimetallic supported catalyst according to claim 8 in hydrogenation reactions with 5-hydroxymethylfurfural, 3-hydroxymethylcyclopentanol and 3-hydroxymethylcyclopentanone as substrates.

10. A method for preparing BHMTHF by catalytic hydrogenation of 5-HMF is characterized by comprising the following steps: the method comprises the following steps:

adding 5-HMF, a solvent and the non-noble bimetal supported catalyst according to claim 8 into a batch type closed high-pressure reaction kettle, and carrying out catalytic selective hydrogenation reaction under stirring; after the reaction is finished, the reaction product is cooled to room temperature, the pressure is released, further preferably, the product is subjected to centrifugal separation, and the non-noble bimetal supported catalyst is separated by a magnet;

preferably, the dosage of the non-noble bimetallic supported catalyst is 1/10-1/2, preferably 3/10 of 5-HMF, the initial pressure of hydrogen is 1-6 MPa, the reaction temperature is 90-130 ℃, preferably 100-120 ℃, and the reaction time is 1-6 hours, preferably 2-5 hours; the stirring speed is 300-500r/min, preferably 400 r/min;

the solvent is deionized water; the ratio of the 5-HMF to the solvent is 1g:10-100ml, preferably 1g: 50 ml.

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