Non-noble metal alloy catalyst for double-terminal reductive amination reaction of 5-hydroxymethylfurfural and preparation method of non-noble metal alloy catalyst

Abstract

The invention provides a non-noble metal alloy catalyst for double-terminal reductive amination reaction of 5-hydroxymethylfurfural and a preparation method thereof, the catalyst is expressed as M1M2M3 / M1M2M3AlOx, M1 represents a component with amination and hydrogenation potential and is one or more of Fe and Co, M2 represents a component with dehydrogenation potential and is one or more of Ni and Cu, M3 represents a metal additive component and is Zn, and M4 represents a component with hydrogenation potential and is one or more of Fe and Co. One or more of Ga; m1M2M3AlOx is used as a carrier, and is a composite metal oxide formed by carrying out topology on M1M2M3Al-LDHs (Layered Double Hydroxides); according to the catalyst, an LDHs material is used as a precursor, and a series of non-noble metal alloy catalysts composed of different elements are prepared based on element adjustability and topological transformation characteristics of LDHs. The catalyst is used for double-end reductive amination reaction of 5-hydroxymethylfurfural, has high catalytic activity and high target product selectivity, and is outstanding in catalytic performance, good in stability and easy to recover and reuse.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic technology, and particularly relates to a non-noble metal alloy catalyst for the double-terminal reduction amination of 5-hydroxymethylfurfural to a binary primary amine and a preparation method thereof. The catalyst is applied to the complex tandem reaction of multi-functional group molecules. Background Art

[0002] Binary primary amines are key monomers for the production of polyamide polymer materials and play an important role in the national economy. However, at present, the industrialization of diamines mainly relies on petroleum-based raw materials. Although large-scale applications have been successful, there are still problems such as high technical barriers, highly toxic and explosive raw materials, energy-intensive production processes, and pollutant emissions. Therefore, the development of a bio-based tandem synthesis route has a positive effect on low-carbon processes.

[0003] The key platform molecule 5-hydroxymethylfurfural derived from renewable lignocellulosic biomass has the potential to obtain the bis-primary amine 2,5-diaminomethylfuran due to its symmetric structure and rigid furan ring. In the literature "Synthesis of bis(amino)furans from biomass based 5-hydroxymethyl furfural, Journal of Energy Chemistry., 2018, 27, 209-214", the authors first converted the hydroxymethyl group into an amide group through the Ritter reaction in a strong acid atmosphere, then reduced the aldehyde group to a primary amine by reductive amination, and finally obtained 2,5-diaminomethylfuran with a yield of 45.7% through simple hydrolysis. In the literature "Modulating trans-imination and hydrogenation towards the highly selective production of primary diamines from dialdehydes, Green Chem., 2020, 22, 6897", the authors used 2,5-furandicarboxaldehyde as the substrate and inhibited the condensation side reaction of the dialdehyde by introducing the nucleophilic reagent n-butylamine, obtaining 2,5-diaminomethylfuran with a high yield of 95%. However, the above methods involve multiple steps of reactions, are relatively complex to separate, are environmentally unfriendly, and have poor atom economy. The method of obtaining bis-primary amines from 5-hydroxymethylfurfural through a one-pot tandem method via amino alcohols only needs to consider the amination of -C=O and alcohol hydroxyl groups, is environmentally friendly, and has strong atom economy. Although this method has advantages, the complex reaction path and highly reactive imine intermediate species still need to improve the selectivity of bis-primary amines. In the literature "Catalytic Production of Alanine from Waste Glycerol, Angew. Chem. Int. Ed., 2020, 59, 2289-2293", the authors found through DFT calculations that the energy barrier of the dehydrogenation reaction of alcohol hydroxyl groups is much higher than that of the amination hydrogenation reaction. Therefore, in the face of the problem of highly mismatched dehydrogenation and amination rates, how to balance the reaction rates of aldehyde group amination hydrogenation, hydroxymethyl dehydrogenation, and aldehyde group amination hydrogenation has become the key factor affecting the synthesis efficiency.

[0004] From the perspective of sustainable development, the development of non-noble metal catalysts is of great significance. Since the energy barrier of alcohol hydroxyl dehydrogenation is much higher than that of amination hydrogenation, it is necessary to introduce metal promoters to isolate the amination hydrogenation sites to reduce the amination hydrogenation ability while adjusting the electronic state of the active sites to improve the dehydrogenation ability of the catalyst for alcohol hydroxyl groups, so as to balance the reaction rates of aldehyde amination hydrogenation, hydroxymethyl dehydrogenation and aldehyde amination hydrogenation to complete relay catalysis. Thus, to achieve the above goals, not only a reasonable selection of non-noble metal compositions is required to meet the multifunctions of amination, hydrogenation and dehydrogenation, but also the alloying means need to be controlled to achieve a uniform arrangement of metal promoters among multifunctional sites to achieve a synergistic matching effect.

[0005] The preparation of non-noble metal alloys is often limited by the solubility of metal ions, resulting in difficult precise control of homogeneous multi-element alloys. Based on the layered double hydroxide (LDHs) material platform, the present invention breaks through the limitations of metal ion solubility. Based on the element-adjustable and topological transformation characteristics of LDHs, a series of non-noble metal alloy catalysts with multifunctions of amination, hydrogenation and dehydrogenation are prepared. Specifically, the non-noble metal alloy catalyst obtained a selectivity of 85-99% for the target product in the selective reductive amination of 5-hydroxymethylfurfural, which not only meets the environmental protection requirements but also greatly reduces the production cost. With the continuous maturity of technology and the realization of large-scale production, this green synthesis method will have great market potential and economic benefits, promoting the transformation of the green and low-carbon economy. Summary of the Invention

[0006] The object of the present invention is to provide a non-noble metal alloy catalyst for the double-end reductive amination of 5-hydroxymethylfurfural to binary primary amines and its preparation method. The catalyst is used for the complex tandem reaction of multi-functional molecules and has outstanding catalytic performance.

[0007] The chemical formula of the catalyst provided by the present invention is M1M2M3 / M1M2M3AlO x , where M1 represents a component with the potential of amination and hydrogenation, which is one or more of Fe and Co, M2 is a component with the potential of dehydrogenation, which is one or more of Ni and Cu, M3 is a metal promoter component, which is one or more of Zn and Ga; M1M2M3AlO x is the carrier, which is a composite metal oxide formed by the topology of M1M2M3Al-LDHs, and x represents the oxygen content in the oxide, x = 1-3; M1M2M3Al-LDHs represents a hydrotalcite with M1, M2, M3, and Al as the lamellar metal elements, and the molar ratio of divalent metal to trivalent metal is 2-4.

[0008] The specific preparation steps of the non-noble metal alloy provided by the present invention are as follows:

[0009] A. Dissolve M1, M2, M3, and Al nitrates in deionized water to prepare a mixed salt solution with a total metal ion concentration of 0.1 - 2.0 mol / L. Here, M1 is one or more of Fe and Co, M2 is one or more of Ni and Cu, M3 is one or more of Zn and Ga, and the molar ratio of divalent metal to trivalent metal is 2 - 4. Prepare an alkali solution with the same volume as the mixed salt solution using NaOH and Na2CO3, with the concentrations of NaOH and Na2CO3 being 0.2 - 1.2 mol / L and 0.2 - 1.6 mol / L respectively.

[0010] B. Drop the mixed salt solution into a three - necked flask at a dropping rate of 2 - 8 mL / min, and simultaneously drop the alkali solution into the three - necked flask at a dropping rate of 2 - 6 mL / min. After the dropping is completed, the pH of the solution is 9 - 10. Crystallize the suspension at 60 - 80 °C with a stirring rate of 400 - 800 rpm. After crystallizing for 8 - 24 h, centrifuge the suspension, wash the precipitate with deionized water until the pH of the supernatant is 7 - 8, and dry it at 40 - 80 °C for 24 - 48 h to obtain M1M2M3Al - LDHs, which are ground into powder for standby.

[0011] C. Heat the M1M2M3Al - LDHs obtained in the above step from room temperature to 400 - 1000 °C at a heating rate of 1 - 20 °C / min in a H2 / N2 atmosphere, hold for 2 - 6 h, and then cool to room temperature and take out to obtain the M1M2M3Al - LDHs catalyst. The above atmosphere is a mixed gas with a H2 / N2 volume ratio of 1 - 9.

[0012] The characteristics of this catalyst are as follows: Using the LDHs material as a precursor, based on the element - adjustable and topological transformation characteristics of LDHs, a series of non - noble metal alloy catalysts with amination, hydrogenation, and dehydrogenation multifunctions are prepared. By introducing metal promoters, the amination - hydrogenation sites are isolated to reduce the amination - hydrogenation ability, while the electronic state of the active sites is adjusted to improve the dehydrogenation ability of the catalyst for alcohol hydroxyl groups. This strategy can effectively balance the reaction rates of aldehyde amination - hydrogenation, hydroxymethyl dehydrogenation, and aldehyde amination - hydrogenation, and improve the selectivity of the catalyst.

[0013] Characterization of the catalyst:

[0014] Figure 1 These are the high - resolution transmission electron microscopy (HRTEM) photos of the catalysts prepared in Examples 1 - 4 and Comparative Examples 1 - 2. It can be seen from the figures that M1M2M3 are uniformly dispersed on the surface of the carrier.

[0015] Figure 2 These are the X - ray diffraction (XRD) spectra of the catalysts prepared in Examples 1 - 4 and Comparative Examples 1 - 2. It can be judged that alloy structures are formed in Examples 1 - 4, while alloy structures are not formed in Comparative Examples 1 - 2.

[0016] Figure 3 X-ray photoelectron spectroscopy (XPS) graphs of the catalysts prepared in Examples 1-4. It can be seen from the graphs that the Ni electron cloud density of the catalyst prepared in Example 4 is relatively high, indicating a stronger electron-rich degree.

[0017] Figure 4 Experimental results of the catalyst prepared in Example 4 in the reductive amination reaction of 5-hydroxymethylfurfural. The results show that the conversion rate of 5-hydroxymethylfurfural reaches 100% at 3 h, and the selectivity of 2,5-diaminomethylfuran is 99% at 12 h.

[0018] Figure 5 Stability bar graph of the reusability of the catalyst prepared in Example 4 in the reductive amination reaction of 5-hydroxymethylfurfural. The catalyst was continuously used 5 times, and the selectivities of 2,5-diaminomethylfuran were 99%, 97.5%, 95.7%, 93.6%, and 92.9% in sequence.

[0019] Advantages of the present invention:

[0020] 1. In this work, by adjusting the elemental composition and ratio of the precursor, a multifunctional non-noble metal alloy catalyst with amination, hydrogenation, and dehydrogenation functions was developed, achieving a high degree of matching between the reaction rates of hydroxymethyl dehydrogenation and aldehyde amination hydrogenation, thereby obtaining a target product with high selectivity.

[0021] 2. The catalyst prepared in the present invention has good universality and reusability in the complex tandem reaction of multi-functional group molecules, and has potential application prospects. Description of the drawings

[0022] Figure 1 HRTEM photos of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2.

[0023] Figure 2 XRD spectra of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2.

[0024] Figure 3 XPS spectra of the catalysts prepared in Examples 1-4.

[0025] Figure 4 Performance time curve of the catalyst prepared in Example 4 in the reductive amination reaction of 5-hydroxymethylfurfural.

[0026] Figure 5 Stability bar graph of the reusability of the catalyst prepared in Example 4 in the reductive amination reaction of 5-hydroxymethylfurfural. Detailed implementation manners

[0027] Example 1

[0028] A. Dissolve 14.4 mmol of Co(NO3)2·6H2O, 4.8 mmol of Ni(NO3)2·6H2O, 4.8 mmol of Ga(NO3)3·9H2O, and 4.8 mmol of Al(NO3)3·9H2O metal precursor salts in 100 mL of deionized water to obtain a mixed salt solution; dissolve 18.2 mmol of Na2CO3 and 50 mmol of NaOH in 100 mL of deionized water to obtain an alkali solution;

[0029] B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2.5 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 mL / min. After dropping, the pH of the solution is 10, and the stirring rate is 400 rpm. Crystallize at 60 °C for 24 h, then centrifuge the suspension, wash the precipitate with deionized water until the supernatant is neutral, and place the precipitate in an oven at 60 °C for 36 h to dry, obtaining the precursor CoNiGaAl-LDHs;

[0030] C. Heat CoNiGaAl-LDHs in a H2 / N2 atmosphere to 900 °C at a heating rate of 10 °C / min, hold for 4 h, then cool to room temperature and take out to obtain CoNiGa / CoNiGaAlO x catalyst, and the above atmosphere is a mixed gas with a H2 / N2 volume ratio of 1:9.

[0031] Comparative Example 1

[0032] A. Dissolve 14.4 mmol of Co(NO3)2·6H2O, 4.8 mmol of Ni(NO3)2·6H2O, and 4.8 mmol of Al(NO3)3·9H2O metal precursor salts in 100 mL of deionized water to obtain a mixed salt solution; dissolve 18.2 mmol of Na2CO3 and 50 mmol of NaOH in 100 mL of deionized water to obtain an alkali solution;

[0033] B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2.5 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 mL / min. After dropping, the pH of the solution is 10, and the stirring rate is 400 rpm. Crystallize at 60 °C for 24 h, then centrifuge the suspension, wash the precipitate with deionized water until the supernatant is neutral, and place the precipitate in an oven at 60 °C for 36 h to dry, obtaining the precursor CoNiAl-LDHs;

[0034] C. Heat CoNiAl-LDHs in a H2 / N2 atmosphere to 900 °C at a heating rate of 10 °C / min, hold for 4 h, then cool to room temperature and take out to obtain CoNi / CoNiAlO xCatalyst, and the above atmosphere is a mixed gas with a volume ratio of H2 / N2 of 1:9.

[0035] Example 2

[0036] A. Dissolve 4.8 mmol of metal precursor salts of Co(NO3)2·6H2O, 4.8 mmol of Ni(NO3)2·6H2O, 4.8 mmol of Cu(NO3)2·6H2O, 4.8 mmol of Zn(NO3)3·6H2O, and 4.8 mmol of Al(NO3)3·9H2O in 100 mL of deionized water to obtain a mixed salt solution; dissolve 18.2 mmol of Na2CO3 and 50 mmol of NaOH in 100 mL of deionized water to obtain an alkali solution.

[0037] B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2.5 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 mL / min. After the dropping is completed, the pH of the solution is 10, and the stirring rate is 400 rpm. Crystallize at 60 °C for 24 h, then centrifuge the suspension, wash the precipitate with deionized water until the supernatant is neutral, and place the precipitate in an oven at 60 °C for 36 h to dry, obtaining the precursor CoNiCuZnAl-LDHs.

[0038] C. Heat CoNiCuZnAl-LDHs in a H2 / N2 atmosphere to 900 °C at a heating rate of 10 °C / min, hold for 4 h, then cool to room temperature and take out to obtain CoNiCuZn / CoNiCuZnAlO x Catalyst, and the above atmosphere is a mixed gas with a volume ratio of H2 / N2 of 1:9.

[0039] Comparative Example 2

[0040] A. Under continuous stirring at 30 °C, disperse 4.8 mmol of Al2O3 powder into 20 mL of deionized water to form a suspension with a solid content of 0.24 mol / L and dissolve it in deionized water, with a stirring rate of 400 rpm. Dissolve 4.8 mmol of Co(NO3)2·6H2O, 4.8 mmol of Ni(NO3)2·6H2O, 4.8 mmol of Cu(NO3)2·6H2O, and 4.8 mmol of Zn(NO3)2·6H2O precursor salts in 5 mL of deionized water to obtain a mixed salt solution, and drop the mixed salt solution drop by drop into the above Al2O3 suspension; continuously stir and heat to 90 °C until the deionized water completely evaporates, obtaining Al2O3 powder loaded with Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , that is, the catalyst precursor, denoted as Co 2+ Ni2+ Cu 2+ Zn 2+ / Al2O3;

[0041] B. Heat Co 2+ Ni 2+ Cu 2+ Zn 2+ / Al2O3 to 900 °C at a heating rate of 10 °C / min in an H2 / N2 atmosphere, hold for 4 h, then cool to room temperature and take out to obtain the CuNi-CoNiZn / Al2O3 catalyst. The above atmosphere is a mixed gas with a volume ratio of H2 / N2 of 1:9.

[0042] Example 3

[0043] A. Dissolve 4.8 mmol of Co(NO3)2·6H2O, 4.8 mmol of Ni(NO3)2·6H2O, 9.6 mmol of Cu(NO3)3·9H2O, 4.8 mol of Ga(NO3)3·9H2O, and 4.8 mmol of Al(NO3)3·9H2O metal precursor salts in 100 mL of deionized water to obtain a mixed salt solution; dissolve 18.2 mmol of Na2CO3 and 50 mmol of NaOH in 100 mL of deionized water to obtain an alkali solution.

[0044] B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2.5 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 mL / min. After the dropping is completed, the pH of the solution is 10 and the stirring rate is 400 rpm. Crystallize at 60 °C for 24 h, then centrifuge the suspension, wash the precipitate with deionized water until the supernatant is neutral, and place the precipitate in an oven at 60 °C for 36 h to obtain the precursor CoNiCuGaAl-LDHs.

[0045] C. Heat CoNiCuGaAl-LDHs to 900 °C at a heating rate of 10 °C / min in an H2 / N2 atmosphere, hold for 4 h, then cool to room temperature and take out to obtain the CoNiCuGa / CoNiCuGaAlO x catalyst. The above atmosphere is a mixed gas with a volume ratio of H2 / N2 of 1:9.

[0046] Example 4

[0047] A. Dissolve 4.8 mmol of Fe(NO3)2·9H2O, 9.6 mmol of Co(NO3)2·6H2O, 9.6 mmol of Ni(NO3)2·6H2O, 9.6 mmol of Cu(NO3)3·9H2O, 4.8 mol of Ga(NO3)3·9H2O, and 4.8 mmol of Al(NO3)3·9H2O metal precursor salts in 100 mL of deionized water to obtain a mixed salt solution; dissolve 18.2 mmol of Na2CO3 and 50 mmol of NaOH in 100 mL of deionized water to obtain an alkali solution;

[0048] B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2.5 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 mL / min. After the dropping is completed, the pH of the solution is 10 and the stirring rate is 400 rpm. Crystallize at 60 °C for 24 h, then centrifuge the suspension, wash the precipitate with deionized water until the supernatant is neutral, and place the precipitate in an oven at 60 °C for 36 h to dry to obtain the precursor FeCoNiCuGaAl-LDHs;

[0049] C. Heat FeCoNiCuGaAl-LDHs to 900 °C at a heating rate of 10 °C / min in a H2 / N2 atmosphere, hold for 4 h, then cool to room temperature and take out to obtain the FeCoNiCuGa / FeCoNiCuGaAlO x catalyst. The above atmosphere is a mixed gas with a H2 / N2 volume ratio of 1:9.

[0050] Application Example 1

[0051] Use the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 above for the reductive amination reaction experiment of 5-hydroxymethylfurfural: Add 0.1 g of 5-hydroxymethylfurfural, 100 mg of catalyst, 0.5 MPa of ammonia gas and 15 mL of methanol into a 40 mL high-pressure reactor, and test at 180 °C and 1.5 MPa of H2 for 12 h. Analyze the composition of the reactants and products by gas chromatography using the internal standard method, and the results are shown in Table 1.

[0052]

[0053] As can be seen from Table 1, the conversion rate of the reductive amination reaction of 5-hydroxymethylfurfural is 100%, and the selectivity of 2,5-diaminomethylfuran on the multifunctional non-precious metal alloy with amination, hydrogenation and dehydrogenation functions reaches 85-99%. Compared with the non-precious metal catalysts reported in the literature, the selectivity is significantly improved. However, the selectivity of 2,5-diaminomethylfuran on the alloy catalyst lacking metal promoters is only 24.3%; using the impregnation method is not conducive to the formation of an alloy structure, and the selectivity of 2,5-diaminomethylfuran is only 64.9%.

Claims

1. A non-noble metal alloy catalyst for the double-terminal reductive amination reaction of 5-hydroxymethylfurfural, characterized in that The catalyst is represented as M1M2M3 / M1M2M3AlO x , where M1 represents a component with amination and hydrogenation potential, which is one or more of Fe and Co; M2 is a component with dehydrogenation potential, which is one or more of Ni and Cu; M3 is a metal promoter component, which is one or more of Zn and Ga; M1M2M3AlO x is a carrier, which is a composite metal oxide formed by the topology of M1M2M3Al-LDHs.

2. A method for preparing the alloy catalyst as claimed in claim 1, characterized in that, It is prepared according to the following specific steps: A. Dissolve M1, M2, M3, and Al nitrates in deionized water to prepare a mixed salt solution with a total metal ion concentration of 0.1 - 2.0 mol / L, where M1 is one or more of Fe and Co, M2 is one or more of Ni and Cu, M3 is one or more of Zn and Ga, and the molar ratio of divalent metal to trivalent metal is 2 - 4; Prepare NaOH and Na2CO3 into an alkali solution with the same volume as the mixed salt solution, and the concentrations of NaOH and Na2CO3 are 0.2 - 1.2 mol / L and 0.2 - 1.6 mol / L respectively; B. Drop the mixed salt solution into a three-necked flask at a dropping rate of 2 - 8 mL / min, and at the same time drop the alkali solution into the three-necked flask at a dropping rate of 2 - 6 mL / min. After the dropping is completed, the pH of the solution is 9 - 10; Crystallize the suspension at 60 - 80 °C with a stirring rate of 400 - 800 rpm. After crystallizing for 8 - 24 h, centrifuge the suspension, wash the precipitate with deionized water until the pH of the supernatant is 7 - 8, and dry it at 40 - 80 °C for 24 - 48 h to obtain M1M2M3Al-LDHs, and grind it into powder for standby; C. Heat the M1M2M3Al-LDHs obtained in the above steps to 400 - 1000 °C at a heating rate of 1 - 20 °C / min in a H2 / N2 atmosphere, keep it for 2 - 6 h and then cool it to room temperature and take it out to obtain the M1M2M3Al-LDHs catalyst. The H2 / N2 atmosphere is a mixed gas with a volume ratio of H2 / N2 of 1 - 9.

3. The application of the catalyst according to claim 1, characterized in that: This catalyst is used for the double-terminal reductive amination reaction of 5-hydroxymethylfurfural.

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