CN116870948B

CN116870948B - Catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid and preparation method thereof

Info

Publication number: CN116870948B
Application number: CN202310846957.7A
Authority: CN
Inventors: 弗朗西斯; 顾君飞; 陈宬; 寇宗魁
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2023-07-11
Filing date: 2023-07-11
Publication date: 2024-04-09
Anticipated expiration: 2043-07-11
Also published as: CN116870948A

Abstract

The invention provides a catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid, which can realize the efficient and high-selectivity conversion of HMF into FDCA under the conditions of weak alkalinity and water solvent; compared with noble metal catalyst, the cost is lower, the catalyst can be recycled for a plurality of times, and the recovery method is simple; compared with the traditional catalyst synthesis and HMF oxidation reaction, the method does not use any organic solvent, only uses deionized water as a solvent, and is environment-friendly; compared with the existing HMF catalytic oxidation, high-pressure oxygen is not required to be introduced in the reaction process, and the reaction only occurs in the air, so that the pressure resistance requirement on equipment is reduced, and the production cost of FDCA is reduced; compared with the currently reported alkaline reaction system, the potassium bicarbonate is weak base, and the strong base can lead the HMF to be degraded to generate byproducts, so that the selectivity of the reaction is improved; the invention uses ZnCo@NC-920 as a catalyst to realize gram-grade reaction for converting HMF into FDCA, and proves that the catalyst has potential for industrial production and wide commercial prospect.

Description

Catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid and preparation method thereof

Technical Field

The invention relates to the technical field of heterogeneous catalysis, in particular to a catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid and a preparation method thereof.

Background

With the increasing consumption of fossil energy and the increasing severity of environmental pollution problems, the development and utilization of renewable energy sources is becoming an important approach to solve the problem. Biomass is the only renewable carbon resource, has the advantages of abundant reserves, wide sources, renewable and no pollution to the environment, and the like, converts biomass carbohydrate into chemicals and fuels with high added value, and is one of the important ways for solving the energy shortage and the environmental pollution. Among the numerous biomass derivatives, 5-Hydroxymethylfurfural (HMF) is the most potential chemical, is an extremely important platform compound for realizing comprehensive utilization of biomass resources, and has wide application in synthesis of biofuels, fine chemicals, solvents, polymers and the like. Among the numerous chemicals further derived from HMF, 2, 5-furandicarboxylic acid (FDCA) is one of twelve biomass-based platform compounds of great value recommended by the U.S. department of energy. FDCA is an important intermediate for synthesizing various fine chemicals and furan-based polymers, and is expected to be applied to polymer production as a substitute for petroleum-based PTA due to its aromatic ring system similar to terephthalic acid (PTA) and diacid structure required for synthesizing polyesters. The polyester material produced by taking FDCA as a raw material is not only non-reproductive toxic and degradable, but also has better performance than phthalate. Therefore, the research of FDCA made of HMF has great market application prospect.

The oxidation reactions currently used to synthesize FDCA from HMF can be largely classified into stoichiometric oxidants, non-noble metal catalysts and noble metal catalysts, depending on the catalyst used. The stoichiometric oxidant converts to lower oxides during oxidation, not only generating environmentally unfriendly byproducts, but also the catalyst cannot be reused. Noble metal catalysts have high catalytic activity and generally can achieve high FDCA yields, but the expensive price of noble metal catalysts limits their commercial production. The non-noble metal catalyst is relatively low in price and rich in resources, so that the non-noble metal single oxide and the non-noble metal composite oxide are widely used for synthesizing FDCA by HMF.

However, in order to obtain excellent catalytic performance when HMF is catalytically oxidized by using most non-noble metal catalysts, it is generally required to introduce pure oxygen under severe reaction conditions (e.g., high temperature and high pressure, strong alkali) or to use a large amount of strong oxidant (e.g., hydrogen peroxide) as an oxygen source, or to perform the reaction in some organic solvents (e.g., dimethyl sulfoxide), which results in a large amount of by-products, and also causes potential safety hazards and resource waste, contrary to the concept of green sustainable development. Therefore, it is necessary to explore the non-noble metal catalysts to achieve efficient and highly selective conversion of HMF to FDCA under mild conditions.

Disclosure of Invention

In view of the above, the invention provides a catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid and a preparation method thereof, which can realize the efficient and high-selectivity conversion of HMF into FDCA under the conditions of alkalescence and water solvent.

The technical scheme of the invention is realized as follows:

in one aspect, the invention provides a method for preparing a catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid, comprising the following steps,

s1, dissolving 2-methylimidazole in deionized water to obtain a 2-methylimidazole aqueous solution, dissolving soluble cobalt salt and soluble zinc salt in a hexadecyl trimethyl ammonium bromide aqueous solution, adding the mixture into the 2-methylimidazole aqueous solution after the mixture is fully dissolved, stirring the mixture, carrying out water bath reaction, centrifuging the mixture to separate purple solid particles, and carrying out vacuum drying to obtain ZnCo-ZIF;

s2, carrying out pyrolysis treatment on the ZnCo-ZIF obtained in the step S1 to obtain a ZnCo bimetallic MOF-derived nitrogen-carbon material, namely a catalyst product.

On the basis of the above technical solution, preferably, the soluble cobalt salt in step S1 is cobalt nitrate hexahydrate, and the soluble zinc salt is zinc nitrate hexahydrate.

On the basis of the technical scheme, preferably, the concentration of the 2-methylimidazole aqueous solution in the step S1 is 55-58 g/L, and the concentration of the mixed aqueous solution of the soluble zinc salt, the soluble cobalt salt and the hexadecyl trimethyl ammonium bromide is 35-37 g/L.

Based on the above technical solution, preferably, in the step S1, the molar ratio of zinc to cobalt is 10 to 12:1.

on the basis of the technical scheme, preferably, in the step S1, the stirring speed is 600-800 rpm, and the temperature is 20-30 ℃; the water bath reaction time is 1-2 hours.

On the basis of the above technical solution, preferably, in step S2, the pyrolysis treatment process conditions are as follows: under the inert atmosphere condition, the temperature is raised to 500-700 ℃ at the temperature rising rate of 3-5 ℃/min from 20-30 ℃, the temperature is kept for 1-2 h, and then the temperature is raised to 800-1000 ℃ at the temperature rising rate of 3-5 ℃/min, and the temperature is kept for 2-3 h.

Further preferably, in the step S2, the inert atmosphere is argon, and the introducing rate is 50-100 cc/min.

In a second aspect, the invention provides a catalyst for the conversion of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid, prepared by the method of the first aspect of the invention.

Based on the technical scheme, the catalytic environment is preferably in a weak alkaline and water solvent condition.

The catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid and the preparation method and application thereof have the following beneficial effects compared with the prior art:

(1) The ZnCo bimetallic MOF-derived nitrogen-carbon material can realize the efficient and high-selectivity conversion of HMF into FDCA under the condition of weak alkalinity and water solvent; compared with noble metal catalysts, the invention has lower cost, can be recycled for a plurality of times, and has simple recovery method; compared with the traditional catalyst synthesis and HMF oxidation reaction, the method does not use any organic solvent, only uses deionized water as a solvent, and is environment-friendly; compared with the existing HMF catalytic oxidation, high-pressure oxygen is not required to be introduced in the reaction process, and the reaction only occurs in the air, so that the pressure resistance requirement on equipment is reduced, and the production cost of FDCA is reduced; compared with the existing alkaline reaction system reported at present, the potassium bicarbonate is weak base, and the strong base can lead the HMF to be degraded to generate byproducts, so that the selectivity of the reaction is improved; the invention uses ZnCo@NC-920 as a catalyst to realize gram-grade reaction for converting HMF into FDCA, and proves that the catalyst has potential for industrial production and wide commercial prospect;

(2) The invention uses 2-methylimidazole and nitreThe coordination reaction of the zinc acid and the cobalt nitrate can obtain a metal organic framework material ZnCo-ZIF, and the synthesized ZnCo-ZIF is uniformly distributed in a cubic porous material with the size of 350-500 nm through a Scanning Electron Microscope (SEM). The ZnCo-ZIF is subjected to high-temperature pyrolysis to obtain a nitrogen-carbon material ZnCo@NC, and a scanning electron microscope (TEM) and a Transmission Electron Microscope (TEM) can show that the catalyst still maintains a three-dimensional porous cube structure after high-temperature pyrolysis, and Co nano particles are uniformly distributed, the size of the Co nano particles is 300-500 nm and is almost similar to that before pyrolysis, so that the structure of the catalyst is not collapsed. Through nitrogen adsorption and desorption tests, the catalyst still maintains a relatively high specific surface area of about 800-1000 m through high-temperature pyrolysis ² g ^-1 . This is because pyrolysis is performed at a temperature higher than the boiling point of zinc, a large amount of zinc is evaporated, the specific surface area of the catalyst is increased, HMF is facilitated to contact with the exposed active sites, and the reaction is sufficiently performed, thereby improving the catalytic activity of the reaction. Experimental results show that ZnCo@NC can catalyze and oxidize HMF into FDCA with 100% selectivity and 100% conversion rate;

(3) Cetyl Trimethyl Ammonium Bromide (CTAB) is adopted to dissolve in deionized water, and the mixture plays a role of a surfactant to adjust the pore size of the synthesized MOF.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is an SEM image of ZnCo-ZIF prepared in example 1;

FIG. 2 is an XRD pattern of ZnCo-ZIF prepared in example 1;

FIG. 3 is an SEM image of ZnCo@NC-920 prepared in example 1;

FIG. 4 is an XRD pattern of ZnCo@NC-920 prepared in example 1;

FIG. 5 is a TEM image of ZnCo@NC-920 prepared in example 1;

FIG. 6 is a graph showing the desorption of nitrogen from ZnCo@NC-920 prepared in example 1;

FIG. 7 is a pore size distribution diagram of ZnCo@NC-920 prepared in example 1.

Detailed Description

The following description of the embodiments of the present invention will clearly and fully describe the technical aspects of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

Example 1

The embodiment provides a ZnCo bimetallic MOF-derived nitrogen-carbon material, and the preparation method comprises the following steps:

1) 9.08g of 2-methylimidazole is dissolved in 160ml of deionized water and uniformly dispersed by ultrasonic waves to obtain a solution A;

2) Dissolving 0.654g of zinc nitrate hexahydrate and 0.058g of cobalt nitrate hexahydrate in 20ml of CTAB aqueous solution containing 10mg, and uniformly dispersing by ultrasonic waves to obtain solution B;

3) Mixing the solution A obtained in the step 1) with the solution B obtained in the step 2), placing the mixture into a water bath kettle for 1h, centrifuging the reacted solution at a rotating speed of 8000rpm for 2 min, pouring out supernatant, adding 10mL of deionized water, centrifuging again, repeating the centrifugal washing process for three times, and finally placing the obtained solid into a vacuum drying box for vacuum drying at 70 ℃ for 12h to obtain purple solid powder ZnCo-ZIF;

4) Placing the purple powder obtained in the step 3) into a porcelain boat, transferring the porcelain boat into a tube furnace, continuously introducing argon with the flow rate of 50cc/min, heating to 600 ℃ at the speed of 3 ℃/min at the temperature of 20-30 ℃, preserving heat for 1h, heating to 920 ℃ at the speed of 3 ℃/min, preserving heat for 2h, and cooling to 20-30 ℃ along with the furnace to obtain a ZnCo bimetallic MOF-derived nitrogen-carbon material ZnCo@NC-920;

the prepared ZnCo bimetallic MOF-derived nitrogen-carbon material is further used as a catalyst for converting HMF into FDCA, and the steps are as follows:

5) The catalyst ZnCo@NC-920 30mg, 0.25mmol of HMF and 0.75mmol of potassium bicarbonate (KHCO) obtained in step 4) were weighed out separately ₃ ) Put in a reaction tube, 1 ml of deionized water was added thereto, and the reaction tube was placed on a magnetic heating stirrer and reacted at 90℃for 16 hours.

The yield of FDCA obtained in this example was tested to be 100%.

Fig. 1 is an SEM image of the precursor ZnCo-ZIF of the bimetallic MOF prepared in step 3) of this example, and it can be seen from the figure that the obtained material has a three-dimensional cube morphology and is uniformly distributed.

FIG. 2 is an XRD pattern of the bimetallic MOF precursor ZnCo-ZIF prepared in step 4) of this example, demonstrating successful preparation of the material.

FIG. 3 is an SEM image of ZnCo@NC-920 prepared in step 4) of the present example, and it can be seen that the ZnCo@NC-920 still maintains a three-dimensional porous structure.

FIG. 4 is an XRD pattern of ZnCo@NC-920 prepared in step 4) of the present example, and three crystal planes (111), (220) and (200) of Co and the corresponding characteristic peaks thereof can be clearly seen, showing that Co exists in the form of nanoparticles in ZnCo@NC-920, while the XRD pattern shows few characteristic peaks of zinc or zinc oxide, showing that the zinc content is very low, which is consistent with the result of ICP.

FIG. 5 is a high resolution transmission electron microscope image of ZnCo@NC-920 prepared in this example, from which it can be seen that Co nanoparticles are uniformly distributed and that a large number of carbon nanotubes are present in the vicinity of the Co nanoparticles.

The metal contents (ICP) in ZnCo-ZIF and ZnCo@NC-920 prepared in example 1 are shown in Table 1.

TABLE 1

Example 2

This embodiment is substantially the same as embodiment 1 except that: no cobalt nitrate hexahydrate was added in step 2).

The yield of FDCA obtained in this example was tested to be 4%.

Example 3

This embodiment is substantially the same as embodiment 1 except that: no zinc nitrate hexahydrate is added in step 2).

The yield of FDCA obtained in this example was tested to be 35%.

Example 4

This example is essentially the same as example 1, except that step 4) is conducted at a pyrolysis treatment temperature of 800 degrees celsius: placing the purple powder obtained in the step 3) into a porcelain boat, transferring the porcelain boat into a tube furnace, continuously introducing argon with the flow rate of 50cc/min, heating to 600 ℃ at the speed of 3 ℃/min at the temperature of 20-30 ℃, preserving heat for 1h, heating to 800 ℃ at the speed of 3 ℃/min, preserving heat for 2h, and cooling to 20-30 ℃ along with the furnace to obtain a ZnCo bimetallic MOF-derived nitrogen-carbon material ZnCo@NC-800;

the yield of FDCA obtained in this example was tested to be 62%.

Example 5

This example is essentially the same as example 1, except that step 4) is conducted at a pyrolysis treatment temperature of 1000℃: placing the purple powder obtained in the step 3) into a porcelain boat, transferring the porcelain boat into a tube furnace, continuously introducing argon with the flow rate of 50cc/min, heating to 600 ℃ at the room temperature at the speed of 3 ℃/min, preserving heat for 1h, heating to 1000 ℃ at the speed of 3 ℃/min, preserving heat for 2h, and cooling to the room temperature along with the furnace to obtain a ZnCo bimetallic MOF-derived nitrogen carbon material ZnCo@NC-1000;

the yield of FDCA obtained in this example was tested to be 71%.

Example 6

This example is essentially the same as example 1, except that the amount of substrate for the catalytic reaction in step 5) is doubled: the catalyst ZnCo@NC-920 60mg obtained in step 4), 0.50mmol of HMF and 0.75mmol of potassium bicarbonate (KHCO) were weighed out separately ₃ ) Placed in a reaction tube, 2 ml of deionized water was added thereto, and the reaction tube was placed on a magnetic heating stirrer and reacted at 90℃for 24 hours.

The yield of FDCA obtained in this example was tested to be 100%.

Example 7

This example is essentially the same as example 1, except that the temperature and time of the catalytic reaction in step 5) are different: the catalyst ZnCo@NC-920 30mg, 0.25mmol of HMF and 0.75mmol of potassium bicarbonate (KHCO) obtained in step 4) were weighed out separately ₃ ) Put in a reaction tube, 1 ml of deionized water was added thereto, and the reaction tube was placed on a magnetic heating stirrer and reacted at 25℃for 48 hours.

The yield of FDCA obtained in this example was 50% as tested.

Example 8

This embodiment is substantially the same as embodiment 1 except that: 8.8g of 2-methylimidazole was dissolved in 160ml of deionized water in step 1).

Example 9

This embodiment is substantially the same as embodiment 1 except that: 9.28g of 2-methylimidazole were dissolved in 160ml of deionized water in step 1).

Example 10

This embodiment is substantially the same as embodiment 1 except that: in step 2), the molar ratio of zinc to cobalt is 10:1, the concentration of the mixed aqueous solution of zinc nitrate hexahydrate, cobalt nitrate hexahydrate and cetyltrimethylammonium bromide was 35g/L.

Example 11

This embodiment is substantially the same as embodiment 1 except that: in step 2), the molar ratio of zinc to cobalt is 12:1, the concentration of the mixed aqueous solution of zinc nitrate hexahydrate, cobalt nitrate hexahydrate and cetyltrimethylammonium bromide was 37g/L.

Example 12

This embodiment is substantially the same as embodiment 1 except that: in the step 4), argon with the flow rate of 75cc/min is introduced, the temperature is raised to 500 ℃ at the speed of 4 ℃/min at 20-30 ℃, the temperature is kept for 2 hours, the temperature is raised to 920 ℃ at the speed of 4 ℃/min, the temperature is kept for 2.5 hours, and the furnace is cooled to 20-30 ℃ to obtain the ZnCo@NC-920 nitrogen carbon material derived from the ZnCo bimetallic MOF.

Example 13

This embodiment is substantially the same as embodiment 1 except that: in the step 4), argon with the flow rate of 100cc/min is introduced, the temperature is raised to 700 ℃ at the speed of 5 ℃/min at 20-30 ℃, the temperature is kept for 1.5h, the temperature is raised to 920 ℃ at the speed of 5 ℃/min, the temperature is kept for 3h, and the furnace is cooled to 20-30 ℃ to obtain the ZnCo@NC-920 nitrogen carbon material derived from the ZnCo bimetallic MOF.

Comparative example 1

This example is essentially the same as example 1, except that KHCO is no longer added in step 5) for the catalytic reaction ₃ : 30mg of the catalyst ZnCo@NC-920 obtained in the step 4) and 0.25mmol of HMF are weighed respectively, placed in a reaction tube, 1 ml of deionized water is weighed and added, the reaction tube is placed on a magnetic heating stirrer, and the reaction is carried out for 16 hours at 90 ℃.

The yield of FDCA obtained in this example was 1% as tested.

Comparative example 2

This example is essentially the same as example 1, except that in step 5) the catalytic reaction is no longer catalyzed: 0.25mmol of HMF and 0.75mmol of potassium bicarbonate were weighed into a reaction tube, 1 ml of deionized water was added thereto, and the reaction tube was placed on a magnetic heating stirrer and reacted at 90℃for 16 hours.

The yield of FDCA obtained in this example was tested to be 0%.

The examples and comparative examples are compared with each other as follows:

from a comparison of examples 1-3, it is seen that Zn and Co act synergistically to Co-catalyze the oxidation of HMF to FDCA. The absence of either Zn or Co results in a significant yield loss.

As is evident from the comparison of examples 1 and 4-5, when the pyrolysis temperature of ZnCo-ZIF is 800 ℃, a large amount of zinc is contained in the catalyst, the specific surface area is small, and when the temperature is higher than the boiling point (907 ℃) of zinc, a large amount of zinc is steamed away, so that more holes are formed on the surface of the catalyst, the specific surface area is increased, the contact of HMF with active sites is better promoted, the activity of the catalyst is improved, however, when the temperature is increased to 1000 ℃, the structure of the catalyst collapses, co nano particles are agglomerated, the activity is reduced, and therefore, the catalyst shows the best catalytic activity when the pyrolysis temperature is 920 ℃.

From a comparison of examples 1 and 6, it is seen that ZnCo@NC-920 can still catalyze HMF to FDCA with high efficiency and high selectivity when the amount of substrate is doubled.

From a comparison of examples 1 and 7, it is seen that ZnCo@NC-920 can also catalyze the oxidation of HMF to FDCA without heating when the reaction time is sufficiently long.

As can be seen from the comparison of example 1 and comparative example 1, znCo@NC-920 is unable to catalyze the oxidation of HMF to FDCA under non-alkaline conditions, indicating that the catalyst is poorly oxidized under non-alkaline conditions.

From a comparison of example 1 and comparative example 2, HMF could not be catalytically oxidized to FDCA without catalyst, demonstrating the catalytic effect of the catalyst.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims

1. A method for preparing a catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid, which is characterized by comprising the following steps: comprises the steps of,

s2, carrying out pyrolysis treatment on the ZnCo-ZIF obtained in the step S1 to obtain a catalyst product;

in the step S1, the concentration of the 2-methylimidazole aqueous solution is 55-58 g/L, and the concentration of the mixed aqueous solution of the soluble zinc salt, the soluble cobalt salt and the hexadecyl trimethyl ammonium bromide is 35-37 g/L;

in the step S1, the molar ratio of zinc to cobalt is 10-12: 1, a step of;

in the step S1, the stirring speed is 600-800 rpm, and the temperature is 20-30 ℃; the water bath reaction time is 1-2 hours;

in the step S2, the pyrolysis treatment process conditions are as follows: under the inert atmosphere condition, starting from 20-30 ℃, heating to 500-700 ℃ at the heating rate of 3-5 ℃/min, preserving heat for 1-2 h, heating to 800-1000 ℃ at the heating rate of 3-5 ℃/min, and preserving heat for 2-3 h;

in the step S2, the inert atmosphere is argon, and the introducing speed is 50-100 cc/m;

the catalyst prepared by the preparation method is used for catalyzing the conversion of 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid, and the catalysis environment is in a weak alkaline and water solvent condition.

2. The method for preparing the catalyst for converting 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid according to claim 1, wherein the method comprises the following steps: in the step S1, the soluble cobalt salt is cobalt nitrate hexahydrate, and the soluble zinc salt is zinc nitrate hexahydrate.