A kind of coral-like solid acid catalyst Al-MCM-41 and its preparation method and application
By preparing an Al-MCM-41 catalyst with a coral-like hierarchical porous structure, the problems of poor catalytic performance and long synthesis cycle of existing catalysts were solved, and efficient catalytic decarboxylation of γ-valerol to prepare butene was achieved, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2023-11-15
- Publication Date
- 2026-06-16
AI Technical Summary
Existing catalysts for the decarboxylation of γ-valerol to butene have poor catalytic performance, complex production processes, high costs, poor stability, and limited variety, and the catalyst synthesis cycle is long.
Using Al-MCM-41 catalyst with a coral-like hierarchical porous structure, a solid acid catalyst with a special morphology and structure was synthesized by changing the preparation method of MCM-41 matrix. The aluminum content was 5-9 wt.%, the specific surface area was 881-644 m2·g-1, the pore size was 2.6-2.7 nm, and the total pore volume was 0.56-0.73 cm3·g-1.
The method achieves efficient catalytic decarboxylation of γ-valerol to prepare butene in a short time. It has high catalytic activity, with a reaction temperature of 300℃ and a reaction time of 90 min, and a butene yield of up to 90%, which is suitable for industrial production.
Smart Images
Figure CN117599835B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, specifically to a coral-like solid acid catalyst Al-MCM-41, its preparation method, and its applications. Background Technology
[0002] Butene, as an important chemical raw material, can be used not only to produce fuels such as high-octane gasoline, but also to synthesize plasticizers, surfactants, detergents, lubricants, and more. Fluid catalytic cracking (FCC) is the most widely used butene production process, meeting 70% of the world's butene demand. However, the continued consumption of fossil fuels caused by traditional petroleum cracking is not conducive to the sustainable industrial production of butene. Current technological development places greater emphasis on the development and utilization of biomass resources.
[0003] γ-valerol (GVL), a biomass platform compound, has attracted widespread attention as a green and renewable energy source. It can be readily produced from levulinic acid (from wood or agricultural waste through the catalytic hydrogenation of cellulose and hemicellulose). In 2010, James A. Dumesic's group at the University of Wisconsin (Science, 2010, 327, 1110) first reported that biomass-derived GVL could be catalytically converted into equimolar amounts of butene and carbon dioxide via a solid acid catalyst. This opened a new avenue for developing new butene production processes that utilize sustainable resources cleanly and efficiently. They achieved a 98% butene yield at 375°C and high pressure (e.g., 36 bar). Using an oligomerization reactor composed of acid catalysts such as HZSM-5 and Amberlyst-70, they catalytically combined butene monomers into condensable olefins. They also investigated the formation process and decarboxylation mechanism of valeric acid, and first proposed the idea of using the biomass derivative γ-valerol to produce renewable fuels.
[0004] In 2013, Dumesic et al. (Chemical Communications, 2013, 49, 7040-7042) used a Lewis acid catalyst, γ-Al₂O₃, to catalyze GVL aqueous solutions to obtain highly selective 1-butene. Under reaction conditions of 375 °C and 0.1 MPa, although the butene yield was low (approximately 10%), the selectivity for 1-butene exceeded 92%. The highest butene yield (approximately 90%) was obtained with the participation of acid; however, the corresponding 1-butene selectivity was only 24%.
[0005] In 2014, Jesse Q. Bond et al. (Catalysis Science & Technology 2014, 4, 2267-2279) found through comparison that only with a large specific surface area and suitable... A higher butene yield can only be obtained with the catalytic action of acid sites, which also proves... Acid sites play a crucial role in the GVL decarboxylation reaction. In 2015, Zhang Suojiang et al. (Green Chemistry, 2015, 17, 1065-1070) synthesized a mesoporous SiO2 / Al2O3 catalyst via a sol-gel method for catalyzing the GVL reaction to butene. The synthesized SiO2 / Al2O3 catalyst had a specific surface area of 398 m². 2 ·g -1 The pore size is 6.9 nm, and the weak acid content is 0.03 mmol·g. -1 At 350℃ for 4 h, the conversion rate of γ-valerolactone was greater than 99%, and the butene yield was as high as 97%. In 2019, Zhang Suojiang's team (Industrial & Engineering Chemistry Research, 2019, 58, 11841-11848.) compared the synthesized high-alumina Nabate-5 molecular sieve with HZSM-5-38, HY, and γ-Al2O3. They found that the high-alumina Nabate-5 catalyst, due to its high Lewis acid content and large micropore size, achieved a butene yield of 98% after reacting at 300℃ for 4.5 h. In 2020, Ding's team (Molecular Catalysis 2020, 497, 111218) prepared an amorphous SiO2-Al2O3 (Si / Al = 4:1), which, after reacting at 375℃, 4.0 MPa, and 0.18 h... -1 At a GVL concentration of 60%, the yield of butene was greater than 97% and remained stable for 50 hours. They found that appropriate weak and strong acid sites were key to GVL ring-opening. Low-acid sites promoted the decarboxylation of pentenoic acid (PEA), while high-acid sites promoted the cleavage of PEA. Furthermore, they developed a method to convert the GVL intermediate butene into C5... + A two-stage integrated system for hydrocarbons, combining SiO2-Al2O3 catalyst with nano-HZSM-5, yielded 57.6% C5 content. + Hydrocarbon yield. In 2020, Lin et al. (Nature Materials, 2020, 19, 1-8) introduced niobium and aluminum into HZSM-5 molecular sieves to synthesize a hydrocarbon that simultaneously possesses Lewis acid and... The acid-supported catalyst NbAlS-1 was synthesized. A 30% GVL aqueous solution was continuously passed through NbAlS-1 at 300 °C and atmospheric pressure, yielding a butene yield as high as 99%. The synthesized niobium-supported catalyst not only adjusted the acidity of the molecular sieve, increasing the butene selectivity, but also suppressed catalyst water poisoning.
[0006] Furthermore, the choice of catalyst matrix is crucial, directly affecting catalytic activity. A matrix with a large specific surface area and suitable pore size can expose more active sites, accelerate mass transport, and improve catalytic performance. Recent research on the decarboxylation of biomass derivative γ-valerolactone to butene has made some breakthroughs, but reports on the synthesis and types of catalysts for this reaction are still relatively few.
[0007] In a previous patent application (CN 114797949 A), our research group obtained a series of Al-MCM-41 catalysts with excellent catalytic performance for the GVL decarboxylation to butene reaction, based on the traditional structure of MCM-41 mesoporous molecular sieves. In this application, by changing the preparation method of the MCM-41 matrix, we obtained MCM-41 mesoporous molecular sieves with a coral-like microstructure and coral-like Al-MCM-41 catalysts. These catalysts exhibit higher activity in catalyzing GVL, achieving higher butene yields in a shorter time. This is something that has not been reported in any literature or patent to date. Summary of the Invention
[0008] To address the problems of poor catalytic performance, complex production processes, high costs, poor stability, and limited variety in existing catalysts for the decarboxylation of γ-valerolactone to butene, this invention provides a method for synthesizing a hierarchical porous catalyst with a unique morphology, short synthesis cycle, mild catalytic reaction conditions, and short reaction time. The resulting catalyst not only has a simple preparation process but also exhibits high catalytic activity for the decarboxylation of the biomass platform compound γ-valerolactone to butene in a relatively short time.
[0009] To achieve the above objectives, the technical solution of this invention is as follows: a coral-like solid acid catalyst Al-MCM-41, wherein the solid catalyst is xwt% Al-MCM-41, and the solid catalyst has coral-like hierarchical pores with a specific surface area diameter of 881-644 μm. 2 ·g -1 The pore size is 2.6–2.7 nm, and the total pore volume is approximately 0.56–0.73 cm³. 3 ·g -1 In addition, the aluminum content is 5–9 wt.%.
[0010] The preparation method of the above-mentioned coral-like solid acid catalyst Al-MCM-41 is as follows:
[0011] 1) The preparation method of the coral-like MCM-41 matrix is as follows:
[0012] Ethanol was added to deionized water and stirred until homogeneous at 40°C. Cetyltrimethylammonium bromide (CTAB) was added and stirred until the solid was completely dissolved. The pH was adjusted to alkalinity and kept constant. Tetraethyl orthosilicate (TEOS) was added to the CTAB aqueous solution. Stirring was continued in a 40°C water bath. The white gel was reacted, washed, dried, and calcined to obtain a coral-like MCM-41 matrix with hierarchical pores.
[0013] 2) The preparation method of xwt% Al-MCM-41 catalyst is as follows:
[0014] A certain mass of anhydrous aluminum chloride is dissolved in ethanol and stirred. Coral-like MCM-41 matrix is added to the solution, and stirring is continued. The ethanol is evaporated, the solution is dried, and then calcined in a muffle furnace to obtain xwt%-Al-MCM-41 catalyst synthesized by impregnation method.
[0015] In the preparation method described above, step 1) involves adjusting the solution to alkalinity by using 25% NH3·H2O to adjust the pH to 11.5.
[0016] In the above preparation method, in step 1), the molar ratio of TEOS to template agent CTAB in the MCM-41 matrix is 1:(0.3-0.6), and the molar ratio of TEOS to ethanol is 1:(0-50).
[0017] In the preparation method described above, step 1) involves a reaction at 100℃-120℃ for 48 hours.
[0018] In the above preparation method, step 1) involves calcining at 550°C for 6 hours.
[0019] In the preparation method described above, step 2) involves calcination at 550°C for 5 hours.
[0020] The aforementioned solid acid catalyst is used in the catalytic reaction of γ-valerol to butene.
[0021] In the above application, γ-valerolactone and the coral-like solid acid catalyst Al-MCM-41 are added to a high-temperature and high-pressure batch reactor. After replacing the air in the reactor with nitrogen, the catalytic reaction is carried out at atmospheric pressure to 6.0 MPa and 280 to 320 °C.
[0022] In the above applications, the mass ratio of γ-valerol to the above catalyst is 1:0.06 to 0.14.
[0023] The hierarchical porous solid acid catalyst described in this invention is used to maintain the powder state or to form conventional catalyst shapes in the field of catalysts, such as granules, strips or sheets, when catalyzing the decarboxylation of γ-valerol to produce butene.
[0024] The beneficial effects of this invention are:
[0025] (1) The method for preparing the hierarchical porous solid acid catalyst used in this invention has mild preparation conditions, simple method, short synthesis cycle, stable performance, and can be mass-produced. The specific surface area of the prepared catalyst is 881-644 μm. 2 ·g -1 The pore size is 2.6–2.7 nm, with macropores of 100–200 nm, and the total pore volume is approximately 0.56–0.73 cm³. 3 ·g -1 .
[0026] (2) The multi-level porous solid acid catalyst obtained by the present invention is not only simple to prepare and has a special structure, but also has high catalytic activity for the decarboxylation of γ-valerol to butene. The butene yield is as high as 90% when the reaction is carried out at a reaction temperature of 300℃, a reaction time of 90min and 700r / min. This catalyst can be applied to future industrial production. Attached Figure Description
[0027] Figure 1 This is a scanning electron microscope image of the MCM-41 substrate obtained in Example 1.
[0028] Figure 2 This is a scanning electron microscope image of the catalyst obtained in Comparative Example 1.
[0029] Figure 3 This is a graph showing the change in the reaction activity of the catalyst obtained in Example 2 for the production of butene from γ-valerolactone as a function of temperature.
[0030] Figure 4 This is a graph showing the change in the reaction activity of the catalyst obtained in Example 1 for the production of butene from γ-valerolactone over time. Detailed Implementation
[0031] To enable those skilled in the art to more fully understand the present invention, the present invention will be described in more detail through the following non-limiting embodiments or comparative examples, but the embodiments or comparative examples do not limit the present invention in any way.
[0032] Example 1: Preparation of matrix S(1) with coral-like solid acid catalyst by hydrothermal synthesis.
[0033] Preparation of the coral-like MCM-41 matrix: At 40°C, 39 g of ethanol was added to 120 mL of deionized water and stirred until homogeneous. Then, 2.6 g of CTAB (hexadecyltrimethylammonium bromide) was added and stirred slowly until the solid was completely dissolved. The solution was adjusted to pH 11.5 using 25% NH3·H2O and kept constant. 3.4 g of TEOS (tetraethyl orthosilicate) was added to the CTAB aqueous solution, and the mixture was stirred for 2 h in a 40°C water bath. The white gel was then transferred to a polytetrafluoroethylene stainless steel reactor and reacted at 100°C for 48 h. Finally, the obtained solid product was washed with ethanol and deionized water. The resulting solid was dried overnight at 60°C and then calcined at 550°C for 6 h to obtain a hierarchical porous coral-like MCM-41 matrix.
[0034] Example 2: Preparation of Coral-like Solid Acid Catalyst S(2) by Impregnation Method
[0035] Preparation of xwt%-Al-MCM-41 catalyst: 0.1038 g of anhydrous aluminum chloride was dissolved in 4.2 mL of ethanol and stirred at room temperature for 4 h. Then, 0.3 g of coral-like MCM-41 matrix was added and stirred for another 4 h. The solid mixture was placed in a 60 °C water bath and stirred until the ethanol was evaporated. The solid product was dried overnight in a 60 °C oven. Finally, the dried sample was calcined in a muffle furnace at 550 °C for 5 h to obtain the S(2) catalyst, which was named 7wt%-Al-MCM-41 catalyst.
[0036] Example 3: Preparation of Coral-like Solid Acid Catalyst S(3) by Impregnation Method
[0037] Following the method described in Example 1, but replacing the 0.1038g of anhydrous aluminum chloride in Example 1 with 0.0148g of anhydrous aluminum chloride, the S(3) catalyst was obtained, and the sample was named 1wt%-Al-MCM-41 catalyst.
[0038] Example 4: Preparation of Coral-like Solid Acid Catalyst S(4) by Impregnation Method
[0039] Following the method described in Example 1, but replacing the 0.1038 g of anhydrous aluminum chloride in Example 1 with 0.0444 g of anhydrous aluminum chloride, the S(4) catalyst was obtained, and the sample was named 3wt%-Al-MCM-41 catalyst.
[0040] Example 5: Preparation of Coral-like Solid Acid Catalyst S(5) by Impregnation Method
[0041] Following the method described in Example 1, but replacing the 0.1038 g of anhydrous aluminum chloride in Example 1 with 0.0741 g of anhydrous aluminum chloride, the S(5) catalyst was obtained, and the sample was named 5wt%-Al-MCM-41 catalyst.
[0042] Example 6: Preparation of Coral-like Solid Acid Catalyst S(6) by Impregnation Method
[0043] Following the method described in Example 1, but replacing the 0.1038 g of anhydrous aluminum chloride in Example 1 with 0.1334 g of anhydrous aluminum chloride, an S(6) catalyst was obtained, and the sample was named 9wt%-Al-MCM-41 catalyst.
[0044] Example 7: Preparation of Coral-like Solid Acid Catalyst S(7) by Impregnation Method
[0045] Following the method described in Example 1, but replacing the 0.1038 g of anhydrous aluminum chloride in Example 1 with 0.2224 g of anhydrous aluminum chloride, the S(7) catalyst was obtained, and the sample was named 15wt%-Al-MCM-41 catalyst.
[0046] Comparative Example 1: Preparation of matrix B with coral-like solid acid catalyst by hydrothermal synthesis (1)
[0047] Following the method described in Example 1, but without the addition of ethanol, catalyst B(1) was obtained, and the sample was named MCM-41 (alcohol-free).
[0048] Comparative Example 2: Preparation of matrix B with coral-like solid acid catalyst by hydrothermal synthesis (2)
[0049] Following the method described in Example 1, but replacing 2.6g CTAB in Example 1 with 1.7843g CTAB, catalyst B(2) was obtained, and the sample was named MCM-41-CTAB(0.3), wherein the molar ratio of TEOS to CTAB was 1:0.3.
[0050] Comparative Example 3: Preparation of matrix B(3) with coral-like solid acid catalyst by hydrothermal synthesis.
[0051] Following the method described in Example 1, but replacing 2.6g of CTAB in Example 1 with 3.5687g of CTAB, catalyst B(3) was obtained, and the sample was named MCM-41-CTAB(0.6), wherein the molar ratio of TEOS to CTAB was 1:0.6.
[0052] Comparative Example 4: Preparation of matrix B(4) with coral-like solid acid catalyst by hydrothermal synthesis.
[0053] Following the method described in Example 1, but replacing the 100°C reaction temperature in Example 1 with a reaction temperature of 110°C, catalyst B(4) was obtained, and the sample was named MCM-41-110.
[0054] Comparative Example 5: Preparation of matrix B(5) with coral-like solid acid catalyst by hydrothermal synthesis.
[0055] Following the method described in Example 1, but replacing the 100°C reaction temperature in Example 1 with a reaction temperature of 120°C, catalyst B(5) was obtained, and the sample was named MCM-41-120.
[0056] Example 8 Evaluation of matrices prepared under different synthesis conditions
[0057] Nitrogen adsorption of S(1) and the catalysts of Comparative Examples 1–5 was measured respectively. Figure 2 The addition of alcohol directly affects the morphology of the catalyst. Without ethanol, it forms strip-like and irregular spherical shapes, no longer the traditional morphology of MCM-41, exhibiting a coral-like structure with macroporous features. Therefore, ethanol should be added during the synthesis process. Figure 1 As can be seen from the table, the S(1) catalyst also possesses a macroporous structure, and the presence of this special structure further enhances the catalyst's performance. The amount of CTAB added and the reaction temperature affect the formation of the catalyst's pore structure. Table 1 shows that the catalyst obtained in Example 1 has a higher specific surface area, a relatively higher total pore volume, and a larger pore size. The higher specific surface area and larger pore volume expose more active sites, which is more conducive to the catalytic reaction. Therefore, the catalyst obtained in Example 1 exhibits better catalytic activity, and the relevant data are listed in Table 1.
[0058] Table 1. Nitrogen adsorption data of catalysts prepared under different synthesis conditions
[0059]
[0060] Example 9: Activity determination of the catalyst prepared in Example 2 for the decarboxylation of γ-valerolactone to butene at different temperatures.
[0061] 1.0 g of γ-valerolactone and 0.1 g of the catalyst prepared in Example 2 were added to a 100 mL high-temperature and high-pressure batch reactor. After purging the reactor with nitrogen to replace the air, the reaction was carried out at atmospheric pressure at 280 °C, 290 °C, 295 °C, 300 °C, 310 °C, 320 °C, and 700 r / min for 120 min. After the reaction was completed, the temperature of the reaction system was allowed to drop to room temperature. The gaseous products generated by the reaction were collected using an aluminum foil gas collection bag for gas chromatography analysis. The liquid products generated in the reactor were collected using a disposable syringe for gas chromatography / mass spectrometry analysis. The yield of butene and the conversion rate of γ-valerolactone were calculated.
[0062] Because the reaction system is a closed system, mass is conserved before and after the reaction. According to the law of conservation of mass, the yield of butene and the conversion rate of γ-valerol can be calculated using the following formula:
[0063]
[0064]
[0065] Formula (1) is the formula for calculating the butene yield. The butene yield is expressed in terms of Y. (C4) This indicates that m0 is the total mass of γ-valerolactone in the initial feed, and m1 is the total mass of the liquid remaining in the reaction system after the gas is released. Furthermore, the gas released in this reaction system consists of equal amounts of butene and carbon dioxide.
[0066] Formula (2) is the formula for calculating the conversion rate of γ-valerolactone. The conversion rate of γ-valerolactone is expressed as conv. (GVL) This indicates that m0 is the total mass of γ-valerolactone in the initial feed, and m2 is the total mass of γ-valerolactone in the remaining liquid product calculated using the external standard method.
[0067] Figure 3 This is a graph showing the relationship between butene yield and temperature during the catalytic reaction of γ-valerolactone to butene using different catalysts obtained in Example 2. The graph shows that when the reaction pressure is atmospheric, the catalyst dosage is 10 wt.% of the reactant γ-valerolactone, and the reaction is continued for 2 hours, the butene yield gradually increases with increasing reaction temperature. At 300°C, the butene yield reaches 93%. As the reaction temperature continues to increase, the reactant conversion in the system is almost complete, and the increase in butene yield slows down without a significant increase. The results indicate that temperature has a significant impact on the catalytic reaction of γ-valerolactone to butene, and the catalyst activity can only be maximized under suitable temperature conditions. Furthermore, the catalyst obtained in Example 2 has great application potential in the catalytic reaction of γ-valerolactone to butene.
[0068] Activity determination of catalysts with different aluminum contents prepared in Example 10 for the decarboxylation of γ-valerol to butene.
[0069] The performance of the catalysts in Examples 1-7 was determined. 1 g of γ-valerolactone and 0.1 g of the catalysts obtained in Examples 1-7 were added to 100 mL of a high-temperature, high-pressure batch reactor. After purging the reactor with nitrogen to replace the air, the reaction was carried out at atmospheric pressure, 300 °C, and 700 r / min for 90 min. After the reaction was completed, the temperature of the reaction system was allowed to drop to room temperature. The gaseous products generated by the reaction were collected using an aluminum foil gas collection bag for gas chromatography analysis; the liquid products generated in the reactor were collected using a disposable syringe for gas chromatography / mass spectrometry analysis. The yield of butene and the conversion rate of γ-valerolactone were calculated, and the relevant results are listed in Table 2.
[0070] Table 2 shows the yield of butene and the conversion rate of γ-valerol after reaction at 300℃ and 700 r / min for 90 min using catalysts with different aluminum contents in each example.
[0071]
[0072] As can be seen from Table 2, under the same reaction temperature, initial pressure, rotation speed and reaction time, comparing catalysts S(1)-S(7), it can be found that the butene yield is 21% without the addition of aluminum. After introducing aluminum into MCM-41, the conversion rate of γ-valerolactone gradually increases. When the aluminum content is greater than 3 wt%, the conversion rate of γ-valerolactone can reach more than 90%. The butene yield shows a trend of first increasing and then decreasing with the increase of aluminum content. The xwt% Al-MCM-41 series catalysts with the introduction of aluminum species can greatly improve the yield and rate of GVL decarboxylation to butene. In a short time, the aluminum impregnation amount from 5 wt.% to 9 wt.% all showed high catalytic activity, and the catalytic activity was not much different and the experimental reproducibility was good. Overall, catalyst S(2) has a better performance in catalyzing the decarboxylation of γ-valerolactone to butene reaction, with the highest butene yield and a γ-valerolactone conversion rate of up to 99%.
[0073] Example 11: Activity determination of the catalyst prepared in Example 1 for the decarboxylation of γ-valerolactone to butene at different reaction times.
[0074] 1.0 g of γ-valerolactone and 0.1 g of the catalyst prepared in Example 2 were added to a 100 mL high-temperature and high-pressure batch reactor. After purging the reactor with nitrogen to replace the air, the reaction was carried out at atmospheric pressure at 300 °C and 700 r / min for 60 min, 80 min, 90 min, 100 min, 110 min, and 120 min, respectively. After the reaction was completed, the temperature of the reaction system was allowed to drop to room temperature. The gaseous products generated by the reaction were collected using an aluminum foil gas collection bag for gas chromatography analysis. The liquid products generated in the reactor were collected using a disposable syringe for gas chromatography / mass spectrometry analysis. The yield of butene and the conversion rate of γ-valerolactone were calculated. The yield of butene and the conversion rate of γ-valerolactone were calculated according to the method described in Example 8.
[0075] Figure 4 This is a graph showing the relationship between butene yield and reaction time during the catalytic reaction of γ-valerolactone to butene using the solid acid catalyst prepared in Example 2. The graph shows that under the conditions of atmospheric pressure, catalyst dosage of 10 wt.% of the reactant γ-valerolactone, and reaction temperature of 300°C, the butene yield gradually increases with increasing reaction time. The butene yield reaches 91% after 90 min of reaction time. Further increases in reaction time do not significantly improve the butene yield. In actual industrial production, shortening the reaction time while maintaining production capacity reduces losses and lowers costs; therefore, 90 min is selected as the optimal reaction time.
Claims
1. The application of a coral-like solid acid catalyst Al-MCM-41 in the catalytic reaction of γ-valerolactone to butene, characterized in that, The preparation method of the coral-like solid acid catalyst Al-MCM-41 is as follows: Preparation of coral-like MCM-41 matrix: At 40℃, 39g of ethanol was added to 120mL of deionized water and stirred until homogeneous. 2.6g of CTAB was added and stirred slowly until the solid was completely dissolved. The solution was adjusted to pH = 11.5 with 25% NH3·H2O and kept constant. 3.4g of TEOS was added to the CTAB aqueous solution and stirred for 2h in a 40℃ water bath. The white gel was transferred to a polytetrafluoroethylene stainless steel reactor and reacted at 100℃ for 48h. Finally, the obtained solid product was washed with ethanol and deionized water and dried at 60℃ overnight. Finally, it was calcined at 550℃ for 6h to obtain a coral-like MCM-41 matrix with hierarchical pores. Preparation of 7wt%-Al-MCM-41 catalyst: 0.1038 g of anhydrous aluminum chloride was dissolved in 4.2 mL of ethanol and stirred at room temperature for 4 h. Then, 0.3 g of coral-like MCM-41 matrix was added and stirred for another 4 h. The solid mixture was placed in a 60 °C water bath and stirred until the ethanol was evaporated. The solid product was dried in a 60 °C oven overnight. Finally, the dried sample was calcined in a muffle furnace at 550 °C for 5 h to obtain 7wt%-Al-MCM-41 catalyst. Alternatively, the preparation method of the coral-like solid acid catalyst Al-MCM-41 described above is as follows: Preparation of coral-like MCM-41 matrix: At 40℃, 39g of ethanol was added to 120mL of deionized water and stirred until homogeneous. 2.6g of CTAB was added and stirred slowly until the solid was completely dissolved. The solution was adjusted to pH = 11.5 with 25% NH3·H2O and kept constant. 3.4g of TEOS was added to the CTAB aqueous solution and stirred for 2h in a 40℃ water bath. The white gel was transferred to a polytetrafluoroethylene stainless steel reactor and reacted at 100℃ for 48h. Finally, the obtained solid product was washed with ethanol and deionized water and dried at 60℃ overnight. Finally, it was calcined at 550℃ for 6h to obtain a coral-like MCM-41 matrix with hierarchical pores. Preparation of 5wt%-Al-MCM-41 catalyst: 0.0741 g of anhydrous aluminum chloride was dissolved in 4.2 mL of ethanol and stirred at room temperature for 4 h. Then, 0.3 g of coral-like MCM-41 matrix was added and stirred for another 4 h. The solid mixture was placed in a 60 °C water bath and stirred until the ethanol was evaporated. The solid product was dried in a 60 °C oven overnight. Finally, the dried sample was calcined in a muffle furnace at 550 °C for 5 h to obtain 5wt%-Al-MCM-41 catalyst. Alternatively, the preparation method of the coral-like solid acid catalyst Al-MCM-41 described above is as follows: Preparation of coral-like MCM-41 matrix: At 40℃, 39g of ethanol was added to 120mL of deionized water and stirred until homogeneous. 2.6g of CTAB was added and stirred slowly until the solid was completely dissolved. The solution was adjusted to pH = 11.5 with 25% NH3·H2O and kept constant. 3.4g of TEOS was added to the CTAB aqueous solution and stirred for 2h in a 40℃ water bath. The white gel was transferred to a polytetrafluoroethylene stainless steel reactor and reacted at 100℃ for 48h. Finally, the obtained solid product was washed with ethanol and deionized water and dried at 60℃ overnight. Finally, it was calcined at 550℃ for 6h to obtain a coral-like MCM-41 matrix with hierarchical pores. Preparation of 9wt%-Al-MCM-41 catalyst: 0.1334 g of anhydrous aluminum chloride was dissolved in 4.2 mL of ethanol and stirred at room temperature for 4 h. Then, 0.3 g of coral-like MCM-41 matrix was added and stirred for another 4 h. The solid mixture was placed in a 60 °C water bath and stirred until the ethanol was evaporated. The solid product was dried in a 60 °C oven overnight. Finally, the dried sample was calcined in a muffle furnace at 550 °C for 5 h to obtain 9wt%-Al-MCM-41 catalyst.
2. The application according to claim 1, characterized in that, γ-valerol and the catalyst were added to a high-temperature and high-pressure batch reactor, and the air in the reactor was replaced with nitrogen. The catalytic reaction was carried out at atmospheric pressure ~6.0 MPa and 280 ~ 320 °C.
3. The application according to claim 1, characterized in that, By mass ratio, γ-valerol:catalyst = 1:0.06 ~0.14.