Method for preparing gamma-valerolactone through one-pot two-step catalysis of xylose

Abstract

The invention relates to a method for preparing gamma-valerolactone through one-pot two-step catalysis of xylose, and belongs to the technical field of biomass energy chemical industry. The method comprises the following steps: by taking xylose as a substrate, catalyzing the xylose to react in an oxygen-free environment by utilizing a catalyst Hbeta-30 so as to convert the xylose into furfural, and separating and removing the catalyst Hbeta-30 in a reaction solution, so as to obtain a furfural stock solution; taking a furfural stock solution as a second reaction substrate solution, adding the cellulose carbon modified Zr / beta catalyst and an isopropanol solvent into the furfural stock solution, and catalyzing the furfural to be efficiently converted into gamma-valerolactone in an oxygen-free environment. According to the method, gamma-valerolactone can be directly prepared from xylose through a one-pot two-step method, separation and purification of unstable intermediate products are avoided, and the method has the advantages of being high in catalytic system integration degree, high in gamma-valerolactone yield and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing gamma-valerolactone by catalyzing xylose in one pot and two steps, belonging to the technical field of biomass energy chemical industry. Background Art

[0002] With the decrease of fossil resources and the increase of 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 chemical substances derived from the catalytic upgrading of lignocellulosic biomass, γ-valerolactone is a highly stable and widely used platform compound with broad industrial application prospects. It can be used as a transportation fuel precursor, fuel additive, fine chemical intermediate, green solvent, etc. The conversion of xylose to γ-valerolactone can be achieved through different chemical pathways, but all involve multiple steps. One of the pathways is from the dehydration of monosaccharides to furfural. Furfural can be reduced to furfuryl alcohol by hydrogenation under the promotion of acid catalysts. Furfuryl alcohol evolves into levulinic acid in water in the presence of acid catalysts. Finally, levulinic acid is hydrogenated to generate hydroxyvaleric acid, which is then lactonized to generate γ-valerolactone.

[0003] In the study of catalytic conversion of xylose to γ-valerolactone, Melero et al. first reported the one-pot direct conversion of xylose to γ-valerolactone on Zr-Al-Beta zeolite, and finally obtained a 34% γ-valerolactone yield under the reaction conditions of 190°C and 10h (Green Chem., 2017, 19, 5114). Similarly, Li et al. also used the method of dealumination of SCM-1 zeolite and loading active metal Zr, and achieved a 36.4% γ-valerolactone yield under the reaction conditions of 170°C and 48h by optimizing the dealumination degree to obtain the best L / B value (Journal of Catalysis 392 (2020) 175–185). Wang et al. used formic acid as a green hydrogen source to synthesize a recyclable chitosan-Ru / PPh3 catalyst system, which catalyzed the reaction of xylose at 170°C for 30 hours to achieve a 37% γ-valerolactone yield (Eur. J. Org. Chem. 2020, 1611–1619). In the study of furfural catalytic conversion to prepare γ-valerolactone, Suh et al. added phosphotungstic acid to regulate the L / B acidity, and the prepared HPA / Zr-Beta catalyst achieved a 70% γ-valerolactone yield under the reaction conditions of 160°C 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-valerolactone, and obtained an 85% γ-valerolactone yield under the reaction conditions of 120°C and 5h (Journal of Catalysis., 2019, 56–67). Although some progress has been made in the research on catalytic conversion of xylose to γ-valerolactone, the reported catalyst modification strategies often involve complex preparation processes such as dealumination, and the long reaction path for preparing γ-valerolactone from xylose and the large number of intermediates result in low selectivity and yield of γ-valerolactone. Especially the step of converting xylose into furfural. From the above reports, the conversion of furfural into γ-valerolactone maintained a relatively high yield, but the yield of γ-valerolactone prepared from xylose was very low. Therefore, the limiting step in the preparation of γ-valerolactone from xylose is the conversion of xylose into furfural, which to a certain extent limits the practical application of xylose in the production of γ-valerolactone. Summary of the invention

[0004] In view of the problems of complex catalyst preparation process, long catalytic conversion reaction time and low product yield in the prior art for catalytic conversion of xylose to prepare γ-valerolactone, the present invention proposes a one-pot two-step catalytic method for preparing γ-valerolactone from xylose, wherein xylose is used as a substrate, and catalyst Hβ-30 is used to catalyze the reaction of xylose into furfural in an anaerobic environment, and the catalyst Hβ-30 in the reaction solution is separated and removed to obtain a furfural stock solution; the furfural stock solution is used as the second reaction substrate solution, and a cellulose carbon-modified Zr / β catalyst and an isopropanol solvent are added to the furfural stock solution, and the furfural is efficiently converted into γ-valerolactone in an anaerobic environment. The present invention can directly prepare γ-valerolactone from xylose in a one-pot two-step method, avoid the separation and purification of unstable intermediates, and has the characteristics of high integration of the catalytic system and high yield of γ-valerolactone.

[0005] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

[0006] (1) adding xylose, a hemicellulose derivative, into an organic solvent to prepare a xylose solution;

[0007] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, and catalyzing the reaction for 30 to 50 minutes at a temperature of 130 to 150° C. in the absence of oxygen to obtain a first reaction solution, and separating and removing the catalyst Hβ-30 to obtain a furfural stock solution;

[0008] (3) Using the furfural stock solution as the second reaction substrate solution, the cellulose carbon-modified Zr / β catalyst and isopropanol are added to the furfural stock solution, and the catalytic reaction is carried out for 8 to 12 hours in the absence of oxygen and at a temperature of 170 to 190° C. to obtain γ-valerolactone.

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

[0010] Preferably, in step (2), the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose 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) comprises the following specific steps:

[0013] 1) adding Hβ-30 zeolite and cellulose to a zirconium salt solution, stirring and reacting at room temperature for 1 to 2 hours, and stirring and reacting at a temperature of 110 to 130° C. until the water is completely evaporated to obtain a catalyst precursor;

[0014] 2) The catalyst precursor is placed in a nitrogen atmosphere, the temperature is uniformly raised to 500-600° C., and the catalyst is calcined at a constant temperature for 2-4 hours to obtain a 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; 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), based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution being 100%, zirconium ions in the zirconium salt solution account for 25-35%.

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

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention uses xylose as a substrate and utilizes a 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 B acid to L acid, and a large specific surface area is conducive to the adsorption and desorption of the substrate and the product, so Hβ-30 has a good effect in catalyzing the conversion of xylose into furfural. Hβ-30 has the characteristics of short reaction time, high furfural selectivity, high reaction substrate concentration, which can reach industrialization, and good circulation effect.

[0020] (2) The cellulose carbon modified Zr / β catalyst of the present invention can be well transhydrogenated because Zr metal is beneficial to the MPV hydrogenation reaction. Adding cellulose for carbon modification is beneficial to better load Zr on the zeolite molecular sieve and to balance B acid and L acid. The catalyst has the advantages of simple catalyst preparation, accelerated reaction efficiency, improved γ-valerolactone selectivity, recyclability, and potential for industrial production.

[0021] (3) The present invention uses furfural stock solution as the second reaction substrate solution, and uses cellulose carbon modified Zr / β catalyst to catalyze the reaction of furfural into γ-valerolactone in an oxygen-free environment, and uses the stock solution of the first step reaction as the substrate, avoiding the separation and purification of unstable intermediates, and has the characteristics of high integration of the catalytic system and high yield of γ-valerolactone;

[0022] (4) The present invention uses a one-pot solution, which can avoid the lengthy separation process and purification process of the intermediate compound in the post-treatment process, thereby saving time and resources and improving the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is the XRD characterization diagram of the cellulose carbon modified Zr / β catalyst in Example 1;

[0024] Figure 2 This is the NH3-TPD characterization diagram of the cellulose carbon modified Zr / β catalyst in Example 1. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

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

[0027] 1) adding Hβ-30 zeolite and cellulose to a zirconium salt solution (Zr(NO3)4 solution), stirring the reaction at room temperature for 1.5 hours, and stirring the reaction at 120°C until the water is completely evaporated to obtain a catalyst precursor; the zirconium ion concentration in the Zr(NO3)4 solution is 0.4 mol / L; based on the total mass of Hβ-30 zeolite and cellulose as 100%, the Hβ-30 zeolite accounts for 80%; based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution as 100%, the zirconium ions in the zirconium salt solution account for 30%;

[0028] 2) placing the catalyst precursor in a nitrogen atmosphere, uniformly heating it to 550° C. and calcining it at a constant temperature for 3 hours to obtain a cellulose carbon-modified Zr / β catalyst;

[0029] The XRD characterization diagram of the cellulose carbon modified Zr / β catalyst in this example is shown in Figure 1 ,from Figure 1 It can be seen that the ZrO2 crystal diffraction peak appears on the catalyst surface, which maintains the characteristic diffraction peak of Hβ-30 zeolite, and its active metal zirconium is evenly dispersed on the catalyst carrier in the form of ZrO2;

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

[0031] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0033] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 40 minutes under anaerobic conditions at a temperature of 140° C., obtaining a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1:1;

[0034] After testing, the furfural yield in this embodiment was 92.8%;

[0035] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalyzing the reaction for 10 hours under the condition of oxygen-free and temperature of 180° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 10%, 20%, and 30%;

[0036] According to gas chromatography, based on the total volume of isopropanol and furfural stock solution as 100%, when the furfural stock solution accounts for 10%, 20%, and 30%, the yields of γ-valerolactone in this embodiment are 71.6%, 70.0%, and 67.5%, respectively.

[0037] Example 2: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 1;

[0038] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0040] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, and catalyzing the reaction for 35 minutes under anaerobic conditions at a temperature of 140° C. to obtain a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1:1;

[0041] After testing, the furfural yield in this example was 78.2%;

[0042] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalyzing the reaction for 10 hours under the condition of oxygen-free and temperature of 170° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 1.5:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 10%;

[0043] According to gas chromatography detection, the yield of γ-valerolactone in this example is 48.6%.

[0044] Example 3: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 1;

[0045] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0047] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 30 minutes in the absence of oxygen and at a temperature of 150° C. to obtain a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1.5:1;

[0048] After testing, the furfural yield in this example was 84.9%;

[0049] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalyzing the reaction for 12 hours under the condition of oxygen-free and temperature of 190° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2.5:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 20%;

[0050] According to gas chromatography detection, the yield of γ-valerolactone in this example is 57.4%.

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

[0052] 1) adding Hβ-30 zeolite and cellulose to a zirconium salt solution (ZrOCl2·8H2O solution), stirring the reaction at room temperature for 1 hour, and stirring the reaction at a temperature of 130°C until the water is completely evaporated to obtain a catalyst precursor; the zirconium ion concentration in the ZrOCl2·8H2O solution is 0.45 mol / L; based on the total mass of Hβ-30 zeolite and cellulose being 100%, the Hβ-30 zeolite accounts for 90%; based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution being 100%, the zirconium ions in the zirconium salt solution account for 25%;

[0053] 2) placing the catalyst precursor in a nitrogen atmosphere, uniformly heating it to 500° C. and calcining it at a constant temperature for 4 hours to obtain a cellulose carbon-modified Zr / β catalyst;

[0054] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0056] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 50 minutes in the absence of oxygen and at a temperature of 130° C. to obtain a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1:1;

[0057] After testing, the furfural yield in this example was 74.2%;

[0058] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalytically reacting for 12 hours under the condition of oxygen-free and temperature of 190° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 10%;

[0059] According to gas chromatography detection, the yield of γ-valerolactone in this example is 53.4%.

[0060] Example 5: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 4;

[0061] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0063] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 30 minutes in the absence of oxygen and at a temperature of 150° C. to obtain a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1.5:1;

[0064] After testing, the furfural yield in this embodiment was 86.8%;

[0065] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalyzing the reaction for 10 hours under the condition of oxygen-free and temperature of 190° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 1:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 30%;

[0066] According to gas chromatography detection, the yield of γ-valerolactone in this example is 53.2%.

[0067] Example 6: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 4;

[0068] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0070] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 45 minutes under anaerobic conditions at a temperature of 130° C., obtaining a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1.5:1;

[0071] After testing, the furfural yield in this embodiment was 83.6%;

[0072] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalytically reacting for 12 hours under the condition of oxygen-free and temperature of 180° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 20%;

[0073] According to gas chromatography detection, the yield of γ-valerolactone in this example is 50.6%.

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

[0075] 1) adding Hβ-30 zeolite and cellulose to a zirconium salt solution (ZrCl4 solution), stirring the reaction at room temperature for 2 hours, and stirring the reaction at a temperature of 110°C until the water is completely evaporated to obtain a catalyst precursor; the zirconium ion concentration in the ZrCl4 solution is 0.35 mol / L; based on the total mass of Hβ-30 zeolite and cellulose being 100%, the Hβ-30 zeolite accounts for 70%; based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution being 100%, the zirconium ions in the zirconium salt solution account for 35%;

[0076] 2) placing the catalyst precursor in a nitrogen atmosphere, uniformly heating it to 600° C. and calcining it at a constant temperature for 2 h to obtain a cellulose carbon-modified Zr / β catalyst;

[0077] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0079] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, and catalyzing the reaction for 30 minutes under anaerobic conditions at a temperature of 150° C. to obtain a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1.2:1;

[0080] After testing, the furfural yield in this embodiment was 75.5%;

[0081] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalyzing the reaction for 12 hours under the condition of oxygen-free and temperature of 180° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 10%;

[0082] According to gas chromatography detection, the yield of γ-valerolactone in this example is 52.0%.

[0083] Example 8: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 7;

[0084] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

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

[0086] (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 45 minutes under anaerobic conditions at a temperature of 130° C., obtaining a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1:1;

[0087] After testing, the furfural yield in this embodiment was 88.6%;

[0088] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalytically reacting for 10 hours under the condition of oxygen-free and temperature of 180° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2.5:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 20%;

[0089] According to gas chromatography detection, the yield of γ-valerolactone in this example is 59.5%.

[0090] Example 9: The cellulose carbon modified Zr / β catalyst of this example adopts the cellulose carbon modified Zr / β catalyst of Example 7;

[0091] A one-pot two-step catalytic method for preparing γ-valerolactone from xylose, the specific steps are as follows:

[0092] (1) adding xylose, a hemicellulose derivative, into 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, adding catalyst Hβ-30 to the xylose solution, catalyzing the reaction for 35 minutes under anaerobic conditions at a temperature of 150° C., obtaining a first reaction solution, and removing the catalyst Hβ-30 by centrifugation to obtain a furfural stock solution; the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 1:1;

[0094] After testing, the furfural yield in this embodiment was 86.3%;

[0095] (3) taking the furfural stock solution as the second reaction substrate solution, adding the cellulose carbon modified Zr / β catalyst and isopropanol to the furfural stock solution, and catalytically reacting for 12 hours under the condition of oxygen-free and temperature of 170° C. to obtain γ-valerolactone; the mass ratio of the cellulose carbon modified Zr / β catalyst to the xylose in step (1) is 2:1; based on the total volume of isopropanol and the furfural stock solution being 100%, the furfural stock solution accounts for 20%;

[0096] According to gas chromatography detection, the yield of γ-valerolactone in this example is 57.6%.

[0097] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing γ-valerolactone from xylose in one-pot two-step catalysis, characterized in that: The specific steps are as follows: (1) adding xylose, a hemicellulose derivative, into an organic solvent to prepare a xylose solution; (2) using a xylose solution as the first reaction substrate solution, adding a catalyst Hβ-30 to the xylose solution, and catalyzing the reaction for 30 to 50 minutes at a temperature of 130 to 150° C. in the absence of oxygen to obtain a first reaction solution, and separating and removing the catalyst Hβ-30 to obtain a furfural stock solution; (3) Using the furfural stock solution as the second reaction substrate solution, the cellulose carbon-modified Zr / β catalyst and isopropanol are added to the furfural stock solution, and the catalytic reaction is carried out for 8 to 12 hours in the absence of oxygen and at a temperature of 170 to 190° C. to obtain γ-valerolactone.

2. The method for preparing γ-valerolactone from xylose in one pot and two steps according to claim 1, characterized in that: 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.

3. The method for preparing γ-valerolactone by catalyzing xylose in one pot and two steps according to claim 1, characterized in that: In step (2), the mass ratio of the catalyst Hβ-30 to the hemicellulose derivative xylose is 0.5 to 1.5:

1.

4. The method for preparing γ-valerolactone from xylose in one pot and two steps according to claim 1, characterized in that: The mass ratio of the cellulose carbon-modified Zr / β catalyst in step (3) to the xylose in step (1) is 1.5 to 3:

1.

5. The method for preparing γ-valerolactone by catalyzing xylose in one pot and two steps according to claim 1 or 4, characterized in that: The preparation method of the cellulose carbon modified Zr / β catalyst in step (3) comprises the following specific steps: 1) adding Hβ-30 zeolite and cellulose to a zirconium salt solution, stirring and reacting at room temperature for 1 to 2 hours, and stirring and reacting at a temperature of 110 to 130° C. until the water is completely evaporated to obtain a catalyst precursor; 2) The catalyst precursor is placed in a nitrogen atmosphere, the temperature is uniformly raised to 500-600° C., and the catalyst is calcined at a constant temperature for 2-4 hours to obtain a cellulose carbon-modified Zr / β catalyst.

6. The method for preparing γ-valerolactone from xylose in one pot and two steps according to claim 5, characterized in that: In the step 1), the zirconium ion concentration in the zirconium salt solution is 0.35-0.45 mol / L; based on the total mass of the Hβ-30 zeolite and the cellulose being 100%, the Hβ-30 zeolite accounts for 70-90%.

7. The method for preparing γ-valerolactone from xylose in one pot and two steps according to claim 5, characterized in that: In step 1), based on the total mass of zirconium ions, Hβ-30 zeolite and cellulose in the zirconium salt solution being 100%, zirconium ions in the zirconium salt solution account for 25-35%.

8. The method for preparing γ-valerolactone from xylose in one pot and two steps according to claim 1, characterized in that: Taking the total volume of the isopropanol and furfural stock solution in step (3) as 100%, the furfural stock solution accounts for 10-30%.

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