Application of high performance flow phase catalytic material prepared based on papermaking waste pulp in henry asymmetric addition

Abstract

The application discloses application of a high-performance flow phase catalytic material prepared based on papermaking waste pulp in Henry asymmetric addition, and belongs to the asymmetric catalysis field. The application method comprises the following steps: S1, mixing an aldehyde compound and a nitroalkane compound to obtain a mixed solution; S2, filling a C3N4 / chitosan / cellulose composite microsphere solid-supported copper catalyst into a micro-channel reactor, continuously feeding distilled water and the mixed solution into the micro-channel reactor, performing Henry asymmetric addition reaction, collecting a product, and obtaining a chiral beta-nitro alcohol compound. The method of the application adopts a C3N4 / chitosan / cellulose composite microsphere solid-supported copper catalyst to catalyze the Henry asymmetric addition reaction in water phase, and simultaneously, the method uses a flow phase technology, and has the advantages of simple operation, mild conditions, low price, green environmental protection and the like.

Description

Technical Field

[0001] This invention relates to the field of asymmetric catalysis, specifically to the application of high-performance mobile phase catalytic materials prepared from papermaking waste pulp in Henry's asymmetric addition. Background Technology

[0002] The Henry reaction is a classic C-C bonding reaction in which aldehydes and nitroalkanes undergo an asymmetric addition reaction under the catalysis of a catalyst to yield chiral β-nitro alcohols. Chiral β-nitro alcohols have a wide range of applications and can be further converted into important organic synthetic intermediates such as 1,2-amino alcohols and α-hydroxycarboxylic acids. Due to the importance of this classic named reaction, the Henry reaction is widely used in the synthesis of pharmaceutical intermediates and natural products.

[0003] Two chiral molecules that are mirror enantiomers of each other can produce completely different or even opposite effects. For example, food may taste sweet or bitter, or a drug may be toxic or non-toxic. This is because the basic building blocks of living organisms, such as proteins, nucleic acids, and carbohydrates, are almost all single-chiral. The human body, as a chiral environment, may exhibit completely different recognition effects on exogenous chiral molecules such as the enantiomers of food and drugs. Currently, scientists can separate racemic mixtures using chemical methods, enzymatic digestion, seed crystallization, column chromatography, etc., to obtain only one valuable chiral molecule. Among these, asymmetric catalytic synthesis is currently recognized as the most efficient method for obtaining single enantiomeric chiral molecules. In 1992, Shibasak first reported the Henry asymmetric reaction, attracting the attention of chemists worldwide.

[0004] In 2003, Evans reported a novel Cu(OAc)2-Box complex catalyzing a highly stereoselective Henry asymmetric reaction between nitromethane and aldehydes. Yiels reached up to 95%, and enantiomeric excess percentages (ee) reached up to 94%; however, the catalyst was difficult to recover and reuse.

[0005] In 2007, Feng designed and synthesized a novel N,N'-dioxide-Copper(I) complex. Due to the significant power-gathering properties of N-oxides, they have been widely applied in asymmetric reactions of organometallic compounds. This catalytic system can be applied to various aromatic and aliphatic aldehydes, yielding high yields of nitro alcohol compounds, with enantiomeric excess percentages (ee) reaching up to 98%. Furthermore, it can catalyze the Henry asymmetric reaction of α-keto esters to generate optically active α-hydroxy-β-nitro ester compounds, with enantiomeric excess percentages (ee) reaching up to 99%. However, the high cost of this catalytic system limits industrial production to some extent.

[0006] Therefore, for the Henry asymmetric reaction, catalysts with better selective performance have been developed based on the spatial selectivity of the reaction substrate, resulting in improved reaction activity. However, the reaction suffers from problems such as low catalytic efficiency, high cost, inability to recycle the catalyst, large-scale use of strong bases, and unsuitability for industrial production, which greatly limits its application in practical production.

[0007] Therefore, it is of great significance to provide a new method for Henry's asymmetric addition reaction that is highly efficient, low-cost, mild, environmentally friendly, and yields high results. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides the application of a high-performance mobile phase catalyst material prepared from papermaking waste pulp in Henry's asymmetric addition reaction. This invention employs a high-performance mobile phase catalyst material (C3N4 / chitosan / cellulose composite microsphere supported copper catalyst) prepared from papermaking waste pulp in an aqueous phase to catalyze the Henry's asymmetric addition reaction. It also utilizes mobile phase technology, which has the advantages of high catalytic efficiency, low cost, and environmental friendliness. In addition, it can achieve catalyst recycling while eliminating the need for recovery operations, greatly improving reaction efficiency and making it very suitable for industrial production.

[0009] The objective of this invention is achieved through the following technical solutions.

[0010] The application of high-performance mobile phase catalysts prepared from papermaking waste pulp in Henry's asymmetric addition includes the following steps:

[0011] S1. Mix aldehyde compounds and nitroalkane compounds to obtain a mixed solution;

[0012] S2. A copper catalyst supported on C3N4 / chitosan / cellulose composite microspheres was filled into a microchannel reactor. Then, distilled water and a mixed solution were continuously introduced into the microchannel reactor to carry out a Henry asymmetric addition reaction. The product was collected to obtain chiral β-nitro alcohol compounds.

[0013] The principle behind this invention, which utilizes a copper catalyst immobilized on C3N4 / chitosan / cellulose composite microspheres to enhance the catalytic efficiency of Henry's asymmetric addition reaction in aqueous phase, is as follows: The C3N4 / chitosan / cellulose composite microsphere-immobilized copper catalyst of this invention is soluble in water, as well as in the reaction substrates nitroalkanes and aldehydes. Therefore, the catalyst, reaction substrate, and solvent (water) are mutually soluble and mutually inclusive, thus solving the problem of the organic substrate's insolubility in water. This increases the collision frequency, accelerates the reaction rate, and enables highly efficient Henry's asymmetric addition reaction.

[0014] This invention enhances the chelation effect of copper by adding C3N4 to the catalyst, allowing cellulose to support more copper and ensuring its secure attachment to the cellulose. This results in higher catalytic activity during Henry's asymmetric addition reaction and prevents the supported copper from being washed away in the mobile phase. Furthermore, by immobilizing the copper catalyst with C3N4 / chitosan / cellulose composite microspheres in a microchannel reactor, catalyst recovery is unnecessary after the reaction. For subsequent reactions, a mixture of distilled water and aldehydes / nitroalkanes can be directly introduced into the microchannel reactor. This eliminates the need for a recovery step and allows for the recycling of the catalytic material, significantly improving reaction efficiency.

[0015] This invention utilizes the large number of amino groups contained in chitosan to provide an alkaline environment for the reaction, enabling catalytic reactions to be carried out in pure water without the need to add any alkali, which is in line with the concept of green chemistry.

[0016] Preferably, the preparation method of the C3N4 / chitosan / cellulose composite microsphere supported copper catalyst includes the following steps:

[0017] P1. After drying papermaking waste pulp and mixing it with a nitrogen source, the mixture is calcined at 500-600℃ and then ground to obtain C3N4.

[0018] P2. Mix C3N4 with chitosan powder, cellulose powder, and acetic acid solution to obtain a mixture; then slowly add the mixture dropwise to an ethanol aqueous solution of sodium hydroxide to form transparent microspheres; then add the transparent microspheres to an organic solvent, add glutaraldehyde, and carry out a cross-linking reaction to obtain C3N4 / chitosan / cellulose composite microspheres;

[0019] P3. C3N4 / chitosan / cellulose composite microspheres were immersed in a copper salt solution to obtain a copper catalyst supported on C3N4 / chitosan / cellulose composite microspheres through coordination.

[0020] This invention uses readily available and inexpensive papermaking waste pulp as raw material to prepare C3N4, which is then used to prepare a high-performance mobile phase catalyst material, effectively turning waste into treasure and conforming to the concept of green chemistry. The C3N4 / chitosan / cellulose composite microsphere copper-supported catalyst provided by this invention uses chitosan as a matrix, which is composited with C3N4. Simultaneously, glutaraldehyde is used as a crosslinking agent, and an appropriate amount of cellulose is added for crosslinking modification, and copper ions are loaded to prepare a structurally stable porous composite microsphere material. By crosslinking chitosan with C3N4 and cellulose, the acid resistance of chitosan can be improved, allowing it to exert its adsorption effect well under strongly acidic conditions. Through chemical and physical adsorption, the chelation effect on copper ions is increased.

[0021] Preferably, in step P2, the mass ratio of chitosan powder, cellulose powder, and C3N4 is 1:0.5:(0.05~0.25). More preferably, the mass ratio of chitosan powder, cellulose powder, and C3N4 is 1:0.5:0.1. The structural morphology, thermal stability, and composition of the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst were analyzed using various characterization methods such as SEM, TGA, and XRD. It was found that when the mass ratio of chitosan powder, cellulose powder, and C3N4 was 1:0.5:0.1, the residual copper ions were highest, and the prepared copper-supported catalyst exhibited the best copper-supporting effect.

[0022] Preferably, the cross-linking reaction is carried out at a temperature of 30–50°C for 12–14 hours.

[0023] Preferably, the C3N4 / chitosan / cellulose composite microsphere supported copper catalyst has the structure of formula (1); the aldehyde compound has the structure of general formula (2); the nitroalkane compound has the structure of general formula (3); and the β-nitro alcohol compound has the structure of general formula (4).

[0024]

[0025] R1-CHO formula (2)

[0026] R2CH2NO2 formula (3)

[0027]

[0028] In formula (2), R1 is selected from one of the following substituents:

[0029]

[0030] In equation (3), R2 is hydrogen.

[0031] Preferably, the aldehyde compound is selected from one of the following compounds: benzaldehyde (molecular formula C7H6O), 4-nitrobenzaldehyde (molecular formula C7H5O3N), 4-bromobenzaldehyde (molecular formula C7H5OBr), 4-cyanobenzaldehyde (molecular formula C8H5ON), 2-nitrobenzaldehyde (molecular formula C7H5O3N), 2-chlorobenzaldehyde (molecular formula C7H5OCl), and 2-methylbenzaldehyde (molecular formula C8H8O); the structural formulas of each compound are shown below in sequence:

[0032]

[0033] The corresponding chiral β-nitro alcohols obtained are (S)-1-phenyl-2-nitro alcohol (molecular formula C8H9O3N), (S)-1-(4-nitrophenyl)-2-nitro alcohol (molecular formula C8H8O5N2), (S)-1-(4-bromophenyl)-2-nitro alcohol (molecular formula C8H8O3NBr), (S)-1-(4-cyanophenyl)-2-nitro alcohol (molecular formula C9H8O3N2), (S)-1-(2-nitrophenyl)-2-nitro alcohol (molecular formula C8H8O5N2), (S)-1-(2-chlorophenyl)-2-nitro alcohol (molecular formula C8H8O3NCl), and (S)-(2-methylphenyl)-2-nitro alcohol (molecular formula C9H8O3NBr). 11 O3N); the structural formulas of each compound are shown below in sequence:

[0034]

[0035] In this invention, based on the copper content, the molar ratio of the copper catalyst supported on the C3N4 / chitosan / cellulose composite microspheres to the aldehyde compound is (1-5):100.

[0036] In this invention, the molar ratio of the nitroalkane compound to the aldehyde compound is (1-10):1.

[0037] In this invention, the Henry asymmetric addition reaction is carried out at a temperature of 20–30°C for 10–20 h.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. The C3N4 / chitosan / cellulose composite microsphere copper-supported catalyst provided by this invention has good biocompatibility, is environmentally friendly, can be used in pure water reactions, has good immobilization effect of copper ions, has a long service life, and effectively solves the problems of difficult mass transfer and low catalytic efficiency of traditional catalysts in water.

[0040] 2. The C3N4 / chitosan / cellulose composite microsphere supported copper catalyst provided by this invention requires only a small amount of material to achieve a high conversion rate of the reactants. At the same time, the reaction conditions are mild, no alkali needs to be added, and the reaction is carried out at room temperature, which is simple and easy to operate.

[0041] 3. This invention improves the amount and stability of copper loaded on cellulose by adding C3N4 to the catalytic material, ensuring that the loaded copper is not washed away in the mobile phase, thus enhancing the catalytic activity during Henry's asymmetric addition reaction. Furthermore, by immobilizing the copper catalyst supported on C3N4 / chitosan / cellulose composite microspheres within a microchannel reactor, continuous reaction in a continuous mobile phase significantly improves preparation efficiency. Moreover, after the reaction, catalyst recovery is unnecessary; for the next reaction, a mixture of distilled water and aldehydes / nitroalkanes can be directly introduced into the reaction channel. This eliminates the need for catalyst recovery and allows for the recycling of the catalytic material, making it highly suitable for industrial production.

[0042] 4. This invention uses inexpensive and readily available papermaking waste pulp as raw material to prepare C3N4, effectively turning waste into treasure, which is in line with the concept of green chemistry. Attached Figure Description

[0043] Figure 1 The image shows a SEM image of the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst prepared in this invention. Figure 1 In Figure 'a', the image is a SEM image of the copper catalyst immobilized on C3N4 / chitosan / cellulose composite microspheres in Example 1 (with 0.1 g of C3N4 added). Figure 1 In Figure b, the SEM image of the copper catalyst immobilized on C3N4 / chitosan / cellulose composite microspheres in Example 2 (with 0.05 g of C3N4 added) is shown. Figure 1 In the figure, c is the SEM image of the copper catalyst immobilized on chitosan / cellulose composite microspheres without the addition of C3N4 in Comparative Example 1.

[0044] Figure 2 The image shows the physical specimen of the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst prepared in Example 1.

[0045] Figure 3 The image shows the dynamic light scattering characterization of the copper catalyst immobilized on C3N4 / chitosan / cellulose composite microspheres prepared in Example 1 in aqueous solution. Detailed Implementation

[0046] The applicant will now provide a detailed description of the method of the present invention with reference to specific embodiments, in order to enable those skilled in the art to clearly understand the present invention. However, the following embodiments should not be construed in any way as limiting the scope of protection claimed in the present invention.

[0047] In the following examples and comparative examples, chitosan was sourced from Energie Corporation, and cellulose was sourced from Bailingwei. The papermaking waste pulp used was sourced from Vinda Group.

[0048] Example 1

[0049] This embodiment provides a method for preparing a copper catalyst immobilized on C3N4 / chitosan / cellulose composite microspheres, comprising the following steps:

[0050] P1. Dry the papermaking waste pulp at 100-200℃, then weigh 1g of the dry sample, mix it thoroughly with 0.5g of ammonium chloride, place it in a tube furnace and calcine at 550℃ for 5h, and grind it to obtain C3N4.

[0051] P2. Mix 0.1g of C3N4 with 1g of chitosan powder, 0.5g of cellulose powder, and 5mL of 2% (v / v) acetic acid solution. After ultrasonic treatment, stir at room temperature for 12h to form system one. Dissolve 12g of sodium hydroxide in a mixed solution of 60mL anhydrous ethanol and 40mL distilled water. Stir at room temperature until colorless and transparent. Cool for a period of time to form system two. Then, add system one dropwise to system two using a syringe to form transparent microspheres. Filter and recover the microspheres, and wash with water until neutral to obtain C3N4-doped microspheres. Then, add the above microspheres to 100mL of anhydrous ethanol and add 2mL of 0.02% (v / v) glutaraldehyde ethanol solution. Stir at 50℃ for 12h to obtain C3N4 / chitosan / cellulose composite microspheres.

[0052] P3. The C3N4 / chitosan / cellulose composite microspheres were washed three times with ethanol and distilled water respectively, and then air-dried at room temperature until the surface was free of moisture. They were then soaked in 0.1 g / mL CuSO4 solution at 25 °C for 4 h without stirring, and then for 12 h with stirring. After separation and drying, the copper catalyst supported on the C3N4 / chitosan / cellulose composite microspheres was obtained.

[0053] Example 2

[0054] This embodiment is basically the same as Embodiment 1, except that the mass of C3N4 in step P2 is 0.05g.

[0055] Comparative Example 1

[0056] This comparative example is basically the same as Example 1, except that C3N4 was not added in step P2.

[0057] Figure 1 Here is a SEM image of the catalyst prepared in this invention, wherein, Figure 1 In the image, 'a' is the SEM image of the catalyst from Example 1. Figure 1 In the image, b is the SEM image of the catalyst from Example 2. Figure 1In the figure, c is the SEM image of the catalyst of Comparative Example 1. It can be seen from the figure that when the mass of C3N4 is 0.1g (Example 1), there are more loaded microparticles, the copper content is the highest, and the loading effect is the best. When no C3N4 is added (Comparative Example 1), there are fewer loaded microparticles, indicating that although copper is successfully loaded, the loading effect is poor.

[0058] Figure 2 The image shows a physical picture of the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst prepared in Example 1. As can be seen from the picture, the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst of the present invention is in the form of microspheres.

[0059] Figure 3 The image shows the dynamic light scattering characterization of the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst prepared in Example 1 in aqueous solution. As can be seen from the image, the catalyst material is uniformly dispersed in water, and the particle size is relatively regular. After ultrasonic dispersion, its hydration kinetic particle size is approximately 164 nm.

[0060] Experimental Example 1

[0061] The copper catalyst material immobilized on the C3N4 / chitosan / cellulose composite microspheres of the present invention was used to catalyze the Henry asymmetric addition reaction. The specific steps are as follows:

[0062] S1. Mix 1 mmol of an aldehyde compound and 3 mmol of a nitroalkane compound to obtain a mixed solution;

[0063] S2. 100 mg of catalyst was filled into a microchannel reactor, and then distilled water and the mixed solution obtained in step P1 were continuously circulated into the microchannel reactor. Henry's asymmetric addition reaction was carried out at room temperature for 12 h. The product was collected, separated and purified to obtain chiral β-nitro alcohol compounds.

[0064] Among them, aldehydes have the structure of general formula (2); nitroalkanes have the structure of general formula (3); and β-nitroalcohols have the structure of general formula (4).

[0065] R1-CHO formula (2)

[0066] R2CH2NO2 formula (3)

[0067]

[0068] In formula (2), R1 is selected from one of the following substituents:

[0069]

[0070] In equation (3), R2 is hydrogen.

[0071] The reaction formula is as follows:

[0072]

[0073] The results of the catalysts, aldehydes, and product yields and enantiomeric excess percentages used in each group are shown in Table 1:

[0074] Table 1

[0075]

[0076] As shown in Table 1, the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst of this invention exhibits significant advantages in both yield and enantiomeric excess percentage (ee). This type of catalyst demonstrates excellent catalytic performance in aqueous Henry asymmetric addition reactions, solving the problem of mass transfer difficulties in industrial aqueous reactions. The catalyst in Comparative Example 1, lacking the addition of C3N4, showed poor copper loading, resulting in decreased yield and ee value.

[0077] The characterization data of the product are as follows:

[0078] (S)-1-Pheny-2-nitro alcohol: 1 H NMR (400MHz, CDCl3)7.43-7.34(m,5H,ArH),5.44-5.43(m,1H,CHOH),4.55-4.48(dd,1H,J=1 3.2,9.8Hz,CH2NO2),4.45-4.41(dd,1H,J=13.2,2.9Hz,CH2NO2),2.95(d,1H,J=3.9Hz,OH); 13 C NMR (125MHz, CDCl3)138.4,129.4,129.3,126.3,81.5,71.2;

[0079] (S)-1-(4-nitrophenyl)-2-nitro alcohol: 1 H NMR (400MHz, CDCl3)8.32-8.28(m,2H,ArH),7.64-7.62(m,2H,ArH),5.63(dt,1H,J=8.0,4.0Hz,CHOH),4.64-4.53(m,2H,CH2NO2),3.08(d,J=4.0Hz,OH); 13 C NMR (100MHz, CDCl3)148.1,145.1,126.8,124.2,80.7,69.8;

[0080] (S)-1-(4-bromophenyl)-2-nitro alcohol: 1H NMR(500MHz, CDCl3)7.39-7.33(m,4H,ArH),5.43-5.42(m,1H,CHOH),4.57(dd,1H,J =13.3,9.5Hz,CH2NO2),4.47(dd,1H,J=13.3,2.9,CH2NO2),3.15(d,1H,4.0Hz,OH); 13 C NMR (125MHz, CDCl3)136.4,134.8,129.2,127.4,80.8,70.1;

[0081] (S)-1-(4-cyanophenyl)-2-nitro alcohol: 1 H NMR (500MHz, CDCl3)7.37-7.31(m,4H,ArH),5.56-5.51(m,1H,CHOH),4.57-4.53(dd,2H,J=13.3,9.5Hz,CH2NO2),3.24(d,1H,4.0Hz,OH); 13 C NMR (125MHz, CDCl3)143.4,132.2,126.7,118.4,112.5,78.2,70.4;

[0082] (S)-1-(2-nitrophenyl)-2-nitro alcohol: 1 H NMR (500MHz, CDCl3)8.12-8.07(m,1H,ArH),7.97-7.95(m,1H,ArH),7.79-7.73(m,1H,ArH),7.58-7.54(m,1H,ArH),6.06(ddd,1 H, J=8.8,4.2,2.2Hz,CHOH),4.87(dd,1H,J=13.9,2.2Hz,CH2NO2),4.55(dd,1H,J=13.9,8.8Hz,CH2NO2),3.14(d,1H,4.2Hz,OH); 13 C NMR (100MHz, CDCl3)147.2,134.5,133.8,129.6,128.5,125.1,80.1,66.7;

[0083] (S)-1-(2-chlorophenyl)-2-nitro alcohol: 1H NMR(500MHz,CDCl3)7.63(dd,1H J=8.0,2.0Hz,ArH),7.38-7.33(m,2H,ArH),7.31-7.26(m,1H,ArH),5.85-5.80(m,1H,CHOH),4.6 6(dd,1H,J=13.7,2.4Hz,CH2NO2),4.45(dd,1H,J=13.7,9.8Hz,CH2NO2),3.02(d,1H,4.4Hz,OH); 13 CNMR (125MHz, CDCl3)135.5,131.3,129.8,129.6,127.5,127.4,79.3,67.7;

[0084] (S)-(2-Methylphenyl)-2-nitro alcohol: 1 H NMR(500MHz, CDCl3)7.51-7.49(m,1H,ArH),7.27-7.25(m,2H,ArH),7.19-7.18(m,1H,ArH),5.66-5.64(m,1H,CHOH),4. 54-4.49(dd,1H,J=13.2,9.8Hz,CH2NO2),4.43-4.40(dd,1H,J=13.2,2.4Hz,CH2NO2),2.97(s,1H,OH),2.38(s,3H,CH3); 13 C NMR (125MHz, CDCl3) 136.5, 134.7, 131.1, 128.9, 127.0, 125.8, 80.4, 68.1, 19.1.

[0085] Experimental Example 2

[0086] After completing Experiment 1, the catalyst was used in the next catalytic reaction system. The specific operation was as follows: 1 mmol of an aldehyde compound and 3 mmol of a nitroalkane compound were mixed to obtain a mixed solution; then, distilled water and the mixed solution were continuously circulated into the microchannel reactor again, and the Henry asymmetric addition reaction was carried out at room temperature for 12 h. The product was collected, separated, and purified to obtain chiral β-nitro alcohol compounds. The reusability of the catalyst is shown in Table 2.

[0087] Table 2

[0088]

[0089] As shown in Table 2, the C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst of this invention exhibits good reusability and eliminates the need for catalyst recovery. For subsequent reactions, distilled water and a mixed solution of aldehydes and nitroalkanes can be directly introduced into the microchannel reactor. Furthermore, this reaction system utilizes water as a solvent, making it a green and environmentally friendly process. It provides an economical and environmentally friendly route for the industrial production of chiral β-nitro alcohols, addressing the environmental pollution problems inherent in industrial production.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. The application of high-performance mobile phase catalysts prepared from papermaking waste pulp in Henry's asymmetric addition, characterized in that, Includes the following steps: S1. Mix aldehyde compounds and nitroalkane compounds to obtain a mixed solution; S2. C3N4 / chitosan / cellulose composite microspheres immobilized with copper catalyst were filled into a microchannel reactor. Then, distilled water and a mixed solution were continuously introduced into the microchannel reactor to carry out Henry's asymmetric addition reaction. The product was collected to obtain chiral β-nitro alcohol compounds. The C3N4 / chitosan / cellulose composite microsphere-supported copper catalyst has the structure of formula (1); the aldehyde compound has the structure of general formula (2); the nitroalkane compound has the structure of general formula (3); and the β-nitro alcohol compound has the structure of general formula (4). Equation (1) R1-CHO, formula (2) R2CH2NO2, Equation (3) Equation (4) In formula (2), R1 is selected from one of the following substituents: ； In equation (3), R2 is hydrogen; The preparation method of the C3N4 / chitosan / cellulose composite microsphere supported copper catalyst includes the following steps: P1. After mixing dried papermaking waste pulp with ammonium chloride, the mixture is calcined at 500~600℃ and then ground to obtain C3N4; P2. Mix C3N4 with chitosan powder, cellulose powder, and acetic acid solution to obtain a mixture; then slowly add the mixture dropwise to an ethanol aqueous solution of sodium hydroxide to form transparent microspheres; then add the transparent microspheres to an organic solvent, add glutaraldehyde, and carry out a cross-linking reaction to obtain C3N4 / chitosan / cellulose composite microspheres; P3. C3N4 / chitosan / cellulose composite microspheres were immersed in a copper salt solution to obtain a copper catalyst supported on C3N4 / chitosan / cellulose composite microspheres through coordination.

2. The application according to claim 1, characterized in that, In step P2, the mass ratio of chitosan powder, cellulose powder and C3N4 is 1:0.5:(0.05 ~ 0.25).

3. The application according to claim 2, characterized in that, In step P2, the mass ratio of chitosan powder, cellulose powder and C3N4 is 1:0.5:0.

1.

4. The application according to claim 1, characterized in that, The cross-linking reaction is carried out at a temperature of 30-50℃ for 12-14 hours.

5. The application according to claim 1, characterized in that, Based on copper content, the molar ratio of the copper catalyst supported on the C3N4 / chitosan / cellulose composite microspheres to the aldehyde compound is (1~5):

100.

6. The application according to claim 1, characterized in that, The molar ratio of the nitroalkane compound to the aldehyde compound is (1~10):

1.

7. The application according to claim 1, characterized in that, The Henry asymmetric addition reaction was carried out at a temperature of 20-30°C for 10-20 h.

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