A method for preparing gamma-valerolactone from xylose in one pot in two steps

Abstract

The present application relates to a kind of one-pot two-step catalytic xylose preparation gamma-pentyl lactone method, belong to biomass energy chemical technology field.The present application uses xylose as substrate, in anaerobic environment, using catalyst Hβ-30 catalyzes xylose reaction conversion into furfural, catalyst Hβ-30 catalyst is removed from reaction liquid to obtain furfural crude solution;With furfural crude solution as second reaction substrate solution, cellulose carbon modification Zr / β catalyst and isopropyl alcohol solvent are added into furfural crude solution, in anaerobic environment, catalytic furfural is efficiently converted into gamma-pentyl lactone.The present application can be directly prepared from xylose one-pot two-step method gamma-pentyl lactone, avoid the separation and purification of unstable intermediate product, with the characteristics of high degree of integration of catalytic system, gamma-pentyl lactone yield is high.

Description

Technical Field

[0001] This invention relates to a one-pot, two-step catalytic method for preparing γ-valerol from xylose, belonging to the field of biomass energy chemical technology. Background Technology

[0002] With dwindling fossil resources and increasing demand for fuels and chemicals, there is an urgent need to develop more efficient catalytic pathways to obtain platform chemicals from renewable lignocellulosic biomass. Among the various chemicals derived from the catalytic upgrading of lignocellulosic biomass, γ-valerolactone is a highly stable and versatile platform compound with broad industrial application prospects. It can be used as a precursor for transportation fuels, a fuel additive, a fine chemical intermediate, and a green solvent. The conversion of xylose to γ-valerolactone can be accomplished through different chemical pathways, all involving multiple steps. One pathway involves the dehydration of monosaccharides to furfural. Under the promotion of an acid catalyst, furfural can be hydrogenated to furfuryl alcohol. Furfuryl alcohol then evolves into levulinic acid in water in the presence of an acid catalyst. Finally, levulinic acid is hydrogenated to hydroxyvalerate, which then undergoes a lactone reaction to produce γ-valerolactone.

[0003] In the study of catalytic xylose conversion to γ-valerolactone, Melero et al. first reported a one-pot direct conversion of xylose to γ-valerolactone on Zr-Al-Beta zeolite, achieving a γ-valerolactone yield of 34% under reaction conditions of 190℃ and 10h (Green Chem., 2017, 19, 5114). Similarly, Li et al. also used the method of dealumination of SCM-1 zeolite and loading with active metal Zr, and by optimizing the degree of dealumination to obtain the optimal L / B value, achieved a γ-valerolactone yield of 36.4% under reaction conditions of 170℃ and 48h (Journal of Catalysis 392(2020)175–185). Wang et al. synthesized a recyclable chitosan-Ru / PPh3 catalyst system using formic acid as a green hydrogen source, which catalyzed xylose to achieve a γ-valerol yield of 37% under reaction conditions of 170℃ and 30h (Eur.J.Org.Chem.2020,1611–1619). In the study of furfural catalytic conversion to γ-valerol, Suh et al. added phosphotungstic acid to regulate the L / B acidity, and the prepared HPA / Zr-Beta catalyst achieved a 70% γ-valerol yield under reaction conditions of 160℃ and 24h (Applied Catalysis B: Environmental., 2019, 588–597); Zhang et al. used Zr-HY and Al-HY to catalyze the one-pot conversion of furfural to γ-valerol, and obtained an 85% γ-valerol yield under reaction conditions of 120℃ and 5h (Journal of Catalysis., 2019, 56–67). Although some progress has been made in the study of catalytic conversion of xylose to γ-valerol, the reported catalyst modification strategies often involve complex preparation processes such as dealumination, and due to the long reaction pathway and many intermediate products in the preparation of γ-valerol from xylose, the selectivity and yield of γ-valerol are low. In particular, the step of converting xylose to furfural is problematic. According to the above reports, the conversion of furfural to γ-valerolactone maintained a high yield, but the yield of γ-valerolactone from xylose was very low. Therefore, the limiting step in the preparation of γ-valerolactone from xylose is the conversion of xylose to furfural, which to some extent limits the practical application of xylose in the production of γ-valerolactone. Summary of the Invention

[0004] To address the problems of complex catalyst preparation processes, long catalytic conversion times, and low product yields in existing technologies for the catalytic conversion of xylose to γ-valerol, this invention proposes a one-pot, two-step method for the catalytic conversion of xylose to γ-valerol. Using xylose as a substrate, xylose is catalyzed to convert to furfural in an anaerobic environment using catalyst Hβ-30. The Hβ-30 catalyst is then separated and removed from the reaction solution to obtain a furfural stock solution. Using this furfural stock solution as the second reaction substrate solution, a cellulose carbon-modified Zr / β catalyst and isopropanol solvent are added to the furfural stock solution, and the furfural is efficiently converted to γ-valerol in an anaerobic environment. This invention can directly prepare γ-valerol from xylose in a one-pot, two-step process, avoiding the separation and purification of unstable intermediate products. It features high catalytic system integration and high γ-valerol yield.

[0005] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0006] (1) Xylose, a hemicellulose derivative, is added to an organic solvent to prepare a xylose solution;

[0007] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 130-150℃, the reaction was carried out for 30-50 min to obtain the first reaction solution. The catalyst Hβ-30 was separated and removed to obtain furfural stock solution.

[0008] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 170-190℃, the catalytic reaction was carried out for 8-12 hours to obtain γ-valerol.

[0009] Preferably, the organic solvent in step (1) is 1,4-dioxane or tetrahydrofuran, and the concentration of the xylose solution is 0.05-0.12 mol / L.

[0010] Preferably, the mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose in step (2) is 0.5 to 1.5:1.

[0011] Preferably, the mass ratio of the cellulose carbon-modified Zr / β catalyst in step (3) to the xylose in step (1) is 1 to 3:1.

[0012] Preferably, the preparation method of the cellulose carbon-modified Zr / β catalyst in step (3) includes the following specific steps:

[0013] 1) Add Hβ-30 zeolite and cellulose to a zirconium salt solution, stir at room temperature for 1-2 hours, and then stir at 110-130℃ until all water is evaporated to obtain the catalyst precursor.

[0014] 2) The catalyst precursor was placed in a nitrogen atmosphere and heated at a constant rate to 500-600℃ and calcined at a constant temperature for 2-4 hours to obtain the cellulose carbon-modified Zr / β catalyst.

[0015] More preferably, the zirconium ion concentration in the zirconium salt solution in step 1) is 0.35–0.45 mol / L; and based on the total mass of Hβ-30 zeolite and cellulose being 100%, Hβ-30 zeolite accounts for 70–90%.

[0016] More preferably, in step 1), the zirconium ions in the zirconium salt solution account for 25-35% based on the total mass of zirconium ions, Hβ-30 zeolite, and cellulose in the zirconium salt solution being 100%.

[0017] Preferably, based on the total volume of isopropanol and furfural stock solution in step (3) being 100%, the furfural stock solution accounts for 10-30%.

[0018] The beneficial effects of this invention are:

[0019] (1) This invention uses xylose as a substrate and utilizes the catalyst Hβ-30 to catalyze the conversion of xylose into furfural in an anaerobic environment. In the reaction of catalyzing the conversion of xylose into furfural, Hβ-30 has a moderate acid strength and a suitable ratio of Brønsted acid to Lithotrines. Its large specific surface area is conducive to the adsorption and desorption of substrate and product. Therefore, Hβ-30 has a good effect on catalyzing the conversion of xylose into furfural. Hβ-30 has the characteristics of short reaction time, high furfural selectivity, high substrate concentration that can be industrialized, and good recycling effect.

[0020] (2) The cellulose carbon-modified Zr / β catalyst of the present invention is beneficial to the MPV hydrogenation reaction and can be well converted to hydrogenation. The addition of cellulose for carbon modification is beneficial to better load Zr onto the zeolite molecular sieve and to balance Brønsted acid and Lewis acid. The catalyst has the advantages of simple catalyst preparation, accelerated reaction efficiency, improved γ-valerol selectivity, recyclability, and potential for industrial production.

[0021] (3) In this invention, furfural stock solution is used as the second reaction substrate solution. In an anaerobic environment, cellulose carbon modified Zr / β catalyst is used to catalyze the reaction of furfural to convert it into γ-valerol. The stock solution of the first step reaction is used as the substrate to avoid the separation and purification of unstable intermediate products. It has the characteristics of high integration of catalytic system and high yield of γ-valerol.

[0022] (4) The present invention uses a one-pot solution, which can avoid the lengthy separation process and purification process of intermediate compounds in the post-processing, thereby saving time and resources and improving the yield. Attached Figure Description

[0023] Figure 1The image shows the XRD characterization of the cellulose carbon-modified Zr / β catalyst in Example 1.

[0024] Figure 2 The image shows the NH3-TPD characterization of the cellulose carbon-modified Zr / β catalyst in Example 1. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0026] Example 1: The preparation method of the cellulose carbon-modified Zr / β catalyst in this example includes the following specific steps:

[0027] 1) Hβ-30 zeolite and cellulose were added to a zirconium salt solution (Zr(NO3)4 solution) and stirred at room temperature for 1.5 h. The reaction was then carried out at 120 °C and stirred until all water was evaporated to obtain the catalyst precursor. The zirconium ion concentration in the Zr(NO3)4 solution was 0.4 mol / L. Based on the total mass of Hβ-30 zeolite and cellulose as 100%, Hβ-30 zeolite accounted for 80%. Based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution as 100%, zirconium ions accounted for 30%.

[0028] 2) The catalyst precursor was placed in a nitrogen atmosphere and heated at a constant rate to 550℃ and calcined at a constant temperature for 3h to obtain cellulose carbon modified Zr / β catalyst.

[0029] The XRD characterization diagram of the cellulose carbon-modified Zr / β catalyst in this embodiment is shown below. Figure 1 ,from Figure 1 It can be seen that ZrO2 crystal diffraction peaks appear on the catalyst surface, maintaining the characteristic diffraction peaks of Hβ-30 zeolite, and its active metal zirconium is uniformly dispersed on the catalyst support in the form of ZrO2.

[0030] The NH3-TPD characterization diagram of the cellulose carbon-modified Zr / β catalyst in this embodiment is shown below. Figure 2 ,from Figure 2 It can be seen that the catalyst has acidic properties and is suitable for catalyzing the reaction pathway of xylose to prepare γ-valerol, in which the acidic sites are mainly weak acid sites;

[0031] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0032] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.12 mol / L;

[0033] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 140℃, the reaction was carried out for 40 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1:1.

[0034] The furfural yield in this embodiment was 92.8% as tested.

[0035] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 180℃, the catalytic reaction was carried out for 10 h to obtain γ-valerolactone. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 10%, 20%, and 30%, respectively.

[0036] Gas chromatography analysis showed that, based on the total volume of isopropanol and furfural stock solution as 100%, the yields of γ-valerol in this example were 71.6%, 70.0%, and 67.5% when the furfural stock solution accounted for 10%, 20%, and 30%, respectively.

[0037] Example 2: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 1;

[0038] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0039] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (tetrahydrofuran) to prepare a xylose solution with a concentration of 0.10 mol / L;

[0040] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 140°C, the reaction was carried out for 35 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1:1.

[0041] The furfural yield in this embodiment was 78.2% as tested.

[0042] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 170℃, the catalytic reaction was carried out for 10 h to obtain γ-valerolactone. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 1.5:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 10%.

[0043] According to gas chromatography, the yield of γ-valerol in this embodiment was 48.6%.

[0044] Example 3: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 1;

[0045] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0046] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.15 mol / L;

[0047] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 150°C, the reaction was carried out for 30 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1.5:1.

[0048] The furfural yield in this embodiment was 84.9% as tested.

[0049] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 190℃, the catalytic reaction was carried out for 12 h to obtain γ-valerolactone. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2.5:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 20%.

[0050] According to gas chromatography, the yield of γ-valerol in this example was 57.4%.

[0051] Example 4: The preparation method of the cellulose carbon-modified Zr / β catalyst in this example includes the following specific steps:

[0052] 1) Hβ-30 zeolite and cellulose were added to a zirconium salt solution (ZrOCl2·8H2O solution), and the mixture was stirred at room temperature for 1 hour. The mixture was then stirred at 130℃ until all water was evaporated to obtain the catalyst precursor. The zirconium ion concentration in the ZrOCl2·8H2O solution was 0.45 mol / L. Based on the total mass of Hβ-30 zeolite and cellulose being 100%, Hβ-30 zeolite accounted for 90%. Based on the total mass of zirconium ions, Hβ-30 zeolite, and cellulose in the zirconium salt solution being 100%, zirconium ions accounted for 25%.

[0053] 2) The catalyst precursor was placed in a nitrogen atmosphere and heated at a constant rate to 500℃ and calcined at a constant temperature for 4 hours to obtain the cellulose carbon modified Zr / β catalyst.

[0054] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0055] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (tetrahydrofuran) to prepare a xylose solution with a concentration of 0.10 mol / L;

[0056] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 130°C, the reaction was carried out for 50 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1:1.

[0057] The furfural yield in this embodiment was 74.2% as tested.

[0058] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 190℃, the catalytic reaction was carried out for 12 h to obtain γ-valerol. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 10%.

[0059] Gas chromatography analysis showed that the yield of γ-valerol in this embodiment was 53.4%.

[0060] Example 5: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 4;

[0061] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0062] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.12 mol / L;

[0063] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 150°C, the reaction was carried out for 30 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1.5:1.

[0064] The furfural yield in this embodiment was 86.8% as tested.

[0065] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 190℃, the catalytic reaction was carried out for 10 h to obtain γ-valerolactone. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 1:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 30%.

[0066] According to gas chromatography, the yield of γ-valerol in this embodiment was 53.2%.

[0067] Example 6: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 4;

[0068] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0069] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.10 mol / L;

[0070] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 130°C, the reaction was carried out for 45 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1.5:1.

[0071] The furfural yield in this embodiment was 83.6% as tested.

[0072] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 180℃, the catalytic reaction was carried out for 12 h to obtain γ-valerol. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 20%.

[0073] Gas chromatography analysis showed that the yield of γ-valerol in this embodiment was 50.6%.

[0074] Example 7: The preparation method of the cellulose carbon-modified Zr / β catalyst in this example includes the following specific steps:

[0075] 1) Hβ-30 zeolite and cellulose were added to a zirconium salt solution (ZrCl4 solution), and the mixture was stirred at room temperature for 2 hours. The mixture was then stirred at 110°C until all water was evaporated to obtain the catalyst precursor. The zirconium ion concentration in the ZrCl4 solution was 0.35 mol / L. Based on the total mass of Hβ-30 zeolite and cellulose being 100%, Hβ-30 zeolite accounted for 70%. Based on the total mass of zirconium ions, Hβ-30 zeolite, and cellulose in the zirconium salt solution being 100%, zirconium ions accounted for 35%.

[0076] 2) The catalyst precursor was placed in a nitrogen atmosphere and heated at a constant rate to 600℃ and calcined at a constant temperature for 2 hours to obtain the cellulose carbon modified Zr / β catalyst.

[0077] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0078] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (tetrahydrofuran) to prepare a xylose solution with a concentration of 0.15 mol / L;

[0079] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 150°C, the reaction was carried out for 30 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1.2:1.

[0080] The furfural yield in this embodiment was 75.5% as tested.

[0081] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 180℃, the catalytic reaction was carried out for 12 h to obtain γ-valerol. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 10%.

[0082] According to gas chromatography, the yield of γ-valerol in this embodiment was 52.0%.

[0083] Example 8: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 7;

[0084] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0085] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.12 mol / L;

[0086] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 130°C, the reaction was carried out for 45 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1:1.

[0087] The furfural yield in this embodiment was 88.6% as tested.

[0088] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 180℃, the catalytic reaction was carried out for 10 h to obtain γ-valerolactone. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2.5:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 20%.

[0089] According to gas chromatography, the yield of γ-valerol in this embodiment was 59.5%.

[0090] Example 9: The cellulose carbon-modified Zr / β catalyst in this example uses the cellulose carbon-modified Zr / β catalyst from Example 7;

[0091] A one-pot, two-step catalytic method for the preparation of γ-valerol from xylose, the specific steps of which are as follows:

[0092] (1) Xylose, a hemicellulose derivative, was added to an organic solvent (1,4-dioxane) to prepare a xylose solution with a concentration of 0.15 mol / L;

[0093] (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 was added to the xylose solution. Under anaerobic conditions and a temperature of 150°C, the reaction was carried out for 35 min to obtain the first reaction solution. The catalyst Hβ-30 was removed by centrifugation to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose was 1:1.

[0094] The furfural yield in this embodiment was 86.3% as tested.

[0095] (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol were added to furfural stock solution. Under anaerobic conditions and a temperature of 170℃, the catalytic reaction was carried out for 12 h to obtain γ-valerol. The mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) was 2:1. Based on the total volume of isopropanol and furfural stock solution as 100%, furfural stock solution accounted for 20%.

[0096] According to gas chromatography, the yield of γ-valerol in this embodiment was 57.6%.

[0097] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A one-pot, two-step catalytic method for preparing γ-valerol from xylose, characterized in that, The specific steps are as follows: (1) Xylose, a hemicellulose derivative, is added to an organic solvent to prepare a xylose solution, wherein the organic solvent is 1,4-dioxane or tetrahydrofuran; (2) Using xylose solution as the first reaction substrate solution, catalyst Hβ-30 is added to the xylose solution. Under anaerobic conditions and a temperature of 130~150℃, the catalytic reaction is carried out for 30~50 min to obtain the first reaction solution. The catalyst Hβ-30 is separated and removed to obtain furfural stock solution. The mass ratio of catalyst Hβ-30 to hemicellulose derivative xylose is 0.5~1.5:

1. (3) Using furfural stock solution as the second reaction substrate solution, cellulose carbon-modified Zr / β catalyst and isopropanol are added to furfural stock solution, and the catalytic reaction is carried out for 8-12 h under anaerobic conditions and a temperature of 170-190℃ to obtain γ-valerolactone; the mass ratio of the cellulose carbon-modified Zr / β catalyst to xylose in step (1) is 1.5-3:1; the preparation method of the cellulose carbon-modified Zr / β catalyst includes the following specific steps: 1) Add Hβ-30 zeolite and cellulose to a zirconium salt solution, stir at room temperature for 1-2 hours, and then stir at 110-130℃ until the water is completely evaporated to obtain a catalyst precursor; the zirconium salt is Zr(NO3)4, ZrOCl2·8H2O or ZrCl4. 2) The catalyst precursor was placed in a nitrogen atmosphere and heated at a constant rate to 500~600℃ and calcined at a constant temperature for 2~4h to obtain cellulose carbon modified Zr / β catalyst.

2. The method for one-pot, two-step catalytic preparation of γ-valerol from xylose according to claim 1, characterized in that: Step (1) The concentration of the xylose solution is 0.05~0.12 mol / L.

3. The method for one-pot, two-step catalytic preparation of γ-valerol from xylose according to claim 1, characterized in that: In step 1), the zirconium ion concentration in the zirconium salt solution is 0.35~0.45 mol / L; based on the total mass of Hβ-30 zeolite and cellulose being 100%, Hβ-30 zeolite accounts for 70~90%.

4. The method for one-pot, two-step catalytic preparation of γ-valerol from xylose according to claim 1, characterized in that: In step 1), the total mass of zirconium ions, Hβ-30 zeolite, and cellulose in the zirconium salt solution is 100%, and the zirconium ions account for 25-35% of the zirconium salt solution.

5. The method for one-pot, two-step catalytic preparation of γ-valerol from xylose according to claim 1, characterized in that: Based on the total volume of isopropanol and furfural stock solution in step (3) being 100%, furfural stock solution accounts for 10~30%.

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