A solid base catalyst and its preparation method and application

Abstract

The present invention belongs to the technical field of catalysts. The present invention provides a solid base catalyst and a preparation method and application thereof. The preparation method of the solid base catalyst of the present invention comprises the following steps: reacting tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide to obtain a solid; after heating the solid, adding n-octane, then adding an alkali metal nitrate solution for impregnation, and drying the impregnated product to obtain a precursor; calcining the precursor to obtain a solid base catalyst. The present invention uses tannic acid coordinated with cerium and zirconium as a carrier, supports metal nitrates by a double solvent impregnation method, and prepares a solid base catalyst having a large number of strong alkaline centers by calcination. The solid base catalyst has low mass transfer resistance, high thermal stability, high catalytic activity, low preparation cost, and can be reused. It can effectively catalyze the condensation reaction of methyl isobutyl ketone and furfural, has high catalytic activity, and the catalytic reaction conditions are mild and controllable.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a solid base catalyst and a preparation method and application thereof. Background Art

[0002] As an important heterogeneous catalyst, solid base has attracted widespread attention due to its series of advantages over liquid catalysts. Solid base is much less corrosive than liquid base, which reduces the risk of equipment corrosion; the separation of products and the recovery of catalysts after the reaction become easy, which is conducive to the recovery and use of catalysts. Solid base plays an important role in many organic reactions, including Knoevenagel condensation, Aldol condensation, Michael addition and transesterification. These reactions play a vital role in the synthesis of organic intermediates and fine chemicals.

[0003] The alkalinity of alkali metals or alkali metal oxide solid bases is generally related to the electronegativity of the metal element and the calcination temperature. The higher the calcination temperature, the stronger the alkalinity. This is mainly because after the alkali metal is calcined at high temperature, the metal ions will recombine and arrange themselves, thereby producing lattice defects. The electron cloud density near the lattice oxygen increases, so that the oxygen anions provide strong alkaline sites.

[0004] Solvent-free Aldol condensation of methyl isobutyl ketone (MIBK) and furfural (FA) to FMIBK is a promising method for synthesizing jet fuel precursors. However, due to the low activity of the α-H atom of MIBK, this reaction can only be catalyzed by a strong solid base. The strong solid base catalysis not only has a low reaction conversion rate, but also has a complex and expensive process for preparing the strong solid base catalyst. Therefore, it is promising to develop a solid base catalyst with low preparation cost, high catalytic activity, good stability, and reusability for catalytic synthesis of jet fuel precursors. Summary of the invention

[0005] The purpose of the present invention is to provide a solid base catalyst and a preparation method and application thereof in view of the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a solid base catalyst, comprising the following steps:

[0008] 1) reacting tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide to obtain a solid;

[0009] 2) After heating the solid, adding n-octane, and then adding an alkali metal nitrate solution for impregnation, and drying the impregnated product to obtain a precursor;

[0010] 3) calcining the precursor to obtain a solid base catalyst.

[0011] Preferably, in step 1), the molar volume ratio of tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide is 0.002-0.004 mol: 0.01-0.02 mol: 0.01-0.02 mol: 80-120 mL.

[0012] Preferably, the reaction temperature in step 1) is 70-90° C., and the reaction time is 11-13 h.

[0013] Preferably, in step 2), the heating temperature is 130-140° C., and the heating time is 4-6 hours; the immersion temperature is 40-60° C., and the immersion time is 11-13 hours.

[0014] Preferably, the alkali metal nitrate solution in step 2) is a potassium nitrate solution or a lithium nitrate solution; in the alkali metal nitrate solution, the mass volume ratio of the alkali metal nitrate to the solvent is 0.25 to 1.25 g:

[0015] 2.5mL.

[0016] Preferably, in step 2), the mass volume ratio of the solid to n-octane is 2-3 g:80-120 mL; the mass ratio of the solid to the alkali metal nitrate in the alkali metal nitrate solution is 1:0.1-0.5.

[0017] Preferably, the drying in step 2) comprises a first drying and a second drying;

[0018] The first drying temperature is 145-155°C and the time is 7-8 hours; the second drying temperature is 100-140°C and the time is 3-5 hours.

[0019] Preferably, the calcination temperature in step 3) is 600-800° C., and the calcination time is 8-12 hours.

[0020] The invention also provides a solid base catalyst prepared by the preparation method.

[0021] The present invention also provides the use of the solid base catalyst in catalytic synthesis of biomass fuel, comprising the following steps:

[0022] Methyl isobutyl ketone, furfural and a solid base catalyst are mixed and reacted to obtain a biomass fuel;

[0023] The volume mass ratio of the methyl isobutyl ketone, furfural and solid base catalyst is 1.8-2.2 mL: 0.3-0.7 mL: 0.05-0.15 g;

[0024] The reaction temperature is 130-150° C., and the reaction time is 5-7 hours.

[0025] The beneficial effects of the present invention include the following:

[0026] 1) The present invention uses tannic acid coordinated with cerium and zirconium as a carrier, supports metal nitrate by a double solvent impregnation method, and prepares a solid base catalyst with a large number of strong alkaline centers by roasting. The solid base catalyst has a high specific surface area, low mass transfer resistance, high thermal stability, high catalytic activity, low preparation cost, and can be reused.

[0027] 2) The solid base catalyst of the present invention can effectively catalyze the condensation reaction of methyl isobutyl ketone and furfural, has high catalytic activity, and the catalytic reaction conditions are mild and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The XRD spectra of the solid base catalysts prepared in Examples 2 to 5;

[0029] Figure 2 The XRD spectra of the solid base catalysts of Example 1, Example 6 and Comparative Example 1;

[0030] Figure 3 The XRD spectra of the solid base catalysts prepared in Comparative Examples 2 to 4;

[0031] Figure 4 The XRD spectra of the solid base catalysts prepared in Comparative Examples 5-6 are shown in FIG. DETAILED DESCRIPTION

[0032] The present invention provides a method for preparing a solid base catalyst, comprising the following steps:

[0033] 1) reacting tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide to obtain a solid;

[0034] 2) After heating the solid, adding n-octane, and then adding an alkali metal nitrate solution for impregnation, and drying the impregnated product to obtain a precursor;

[0035] 3) calcining the precursor to obtain a solid base catalyst.

[0036] In the present invention, the molar volume ratio of tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide in step 1) is preferably 0.002-0.004 mol: 0.01-0.02 mol: 0.01-0.02 mol: 80-120 mL, more preferably 0.0025-0.0035 mol: 0.014-0.016 mol: 0.014-0.016 mol: 90-110 mL, and more preferably 0.003 mol: 0.015 mol: 0.015 mol: 100 mL.

[0037] In the present invention, the reaction temperature in step 1) is preferably 70-90°C, more preferably 75-85°C, and more preferably 80°C; the reaction time is preferably 11-13h, more preferably 11.5-12.5h, and more preferably 12h.

[0038] In the present invention, after the reaction in step 1) is completed, the product is preferably filtered, washed and dried in sequence; the washing is preferably carried out alternately with water washing and alcohol washing, and the number of water washing and alcohol washing is independently preferably 3 to 5 times, more preferably 4 times, and the reagent for alcohol washing is preferably anhydrous ethanol; the drying temperature is preferably 80 to 120°C, more preferably 90 to 110°C, more preferably 100°C, and the drying time is preferably 3 to 5h, more preferably 3.5 to 4.5h, more preferably 4h.

[0039] In the present invention, the heating temperature in step 2) is preferably 130-140°C, more preferably 134-136°C, more preferably 135°C, and the heating time is preferably 4-6h, more preferably 4.5-5.5h, more preferably 5h; the immersion temperature is preferably 40-60°C, more preferably 45-55°C, more preferably 50°C, and the immersion time is preferably 11-13h, more preferably 11.5-12.5h, more preferably 12h.

[0040] In the present invention, the alkali metal nitrate solution in step 2) is preferably a potassium nitrate solution or a lithium nitrate solution; in the alkali metal nitrate solution, the mass volume ratio of the alkali metal nitrate to the solvent is preferably 0.25-1.25 g:2.5 mL, more preferably 0.5-1 g:2.5 mL, and more preferably 0.6-0.8 g:2.5 mL.

[0041] In the present invention, the mass volume ratio of the solid and n-octane in step 2) is preferably 2-3 g: 80-120 mL, more preferably 2.4-2.6 g: 90-110 mL, and more preferably 2.5 g: 100 mL;

[0042] The mass ratio of the solid to the alkali metal nitrate in the alkali metal nitrate solution is preferably 1:0.1 to 0.5, more preferably 1:0.2 to 0.4, and even more preferably 1:0.3.

[0043] In the present invention, the drying in step 2) preferably comprises a first drying and a second drying; the temperature of the first drying is preferably 145-155°C, more preferably 148-152°C, more preferably 150°C, and the time is preferably 7-8h, more preferably 7.4-7.6h, more preferably 7.5h; the temperature of the second drying is preferably 100-140°C, more preferably 110-130°C, more preferably 120°C, and the time is preferably 3-5h, more preferably 3.5-4.5h, more preferably 4h.

[0044] In the present invention, the calcination temperature in step 3) is preferably 600-800°C, more preferably 650-750°C, and more preferably 700°C; the calcination time is preferably 8-12h, more preferably 9-11h, and more preferably 10h.

[0045] The invention also provides a solid base catalyst prepared by the preparation method.

[0046] The present invention also provides the use of the solid base catalyst in catalytic synthesis of biomass fuel, comprising the following steps:

[0047] Methyl isobutyl ketone, furfural and a solid base catalyst are mixed and reacted to obtain a biomass fuel;

[0048] The volume mass ratio of the methyl isobutyl ketone, furfural and solid base catalyst is 1.8-2.2 mL: 0.3-0.7 mL: 0.05-0.15 g;

[0049] The reaction temperature is 130-150° C., and the reaction time is 5-7 hours.

[0050] In the present invention, in the application of the solid base catalyst in the catalytic synthesis of biomass fuel, the volume mass ratio of the methyl isobutyl ketone, furfural and solid base catalyst is 1.8-2.2 mL: 0.3-0.7 mL: 0.05-0.15 g, preferably 1.9-2.1 mL: 0.4-0.6 mL: 0.08-0.12 g, and more preferably 2 mL: 0.5 mL: 0.1 g.

[0051] In the present invention, in the application of solid base catalyst in catalytic synthesis of biomass fuel, the reaction temperature is 130-150°C, preferably 135-145°C, and more preferably 140°C; the reaction time is 5-7h, preferably 5.5-6.5h, and more preferably 6h.

[0052] In the present invention, after the reaction of methyl isobutyl ketone, furfural and solid base catalyst, the product is preferably centrifuged, the speed of the centrifugal treatment is preferably 8500-9500 rpm, more preferably 8800-9200 rpm, more preferably 9000 rpm, the time of the centrifugal treatment is preferably 2-4 min, more preferably 2.5-3.5 min, more preferably 3 min.

[0053] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0054] Example 1

[0055] 0.0035 mol of tannic acid, 0.014 mol of cerium chloride heptahydrate, 0.014 mol of zirconium oxychloride octahydrate and 100 mL of N,N-dimethylformamide were reacted at 80°C for 12 hours. The product was filtered and washed alternately with deionized water and anhydrous ethanol, the number of washings with deionized water and anhydrous ethanol was 4 times each, and then dried in an electric blast drying oven at a temperature of 100°C for 4 hours to obtain a solid.

[0056] Put 2.5 g of solid into a round-bottom flask, heat it in an oil bath at 140°C for 6 h, lift the round-bottom flask, immediately add 100 mL of n-octane and plug it with a glass stopper, wait until the temperature of the oil bath drops to 50°C, re-immerse the round-bottom flask in the oil bath, then add potassium nitrate solution (the preparation method of potassium nitrate solution is: dissolve 1 g of potassium nitrate in 2.5 mL of deionized water) and soak for 12 h. After drying the impregnated product in an oil bath at 150°C for 7 h, transfer it to an electric heated forced air drying oven at 120°C and dry it for 4 h to obtain a precursor; calcine the precursor in a muffle furnace at 700°C for 10 h to obtain a solid base catalyst.

[0057] 2 mL of methyl isobutyl ketone, 0.5 mL of furfural and 0.1 g of a solid base catalyst were mixed evenly, and then reacted in an oil bath at a temperature of 140° C. for 6 hours. The product was centrifuged at a speed of 9000 rpm for 3 minutes to obtain biomass fuel.

[0058] The alkali content of the solid alkali catalyst prepared in this example is 6.816 mmol / g, and the yield of biomass fuel is 92.6%.

[0059] Example 2

[0060] The preparation method of the potassium nitrate solution in Example 1 was modified as follows: 0.25 g of potassium nitrate was dissolved in 2.5 mL of deionized water, and other conditions were the same as in Example 1.

[0061] The alkali content of the solid alkali catalyst prepared in this example is 3.264 mmol / g, and the yield of biomass fuel is 84%.

[0062] Example 3

[0063] The preparation method of the potassium nitrate solution in Example 1 was modified as follows: 0.5 g of potassium nitrate was dissolved in 2.5 mL of deionized water, and other conditions were the same as in Example 1.

[0064] The alkali content of the solid alkali catalyst prepared in this example is 3.712 mmol / g, and the yield of biomass fuel is 88.6%.

[0065] Example 4

[0066] The preparation method of the potassium nitrate solution in Example 1 was modified as follows: 0.75 g of potassium nitrate was dissolved in 2.5 mL of deionized water, and other conditions were the same as in Example 1.

[0067] The alkali content of the solid alkali catalyst prepared in this example is 5.52 mmol / g, and the yield of biomass fuel is 97.7%.

[0068] Example 5

[0069] The preparation method of the potassium nitrate solution in Example 1 was modified as follows: 1.25 g of potassium nitrate was dissolved in 2.5 mL of deionized water, and other conditions were the same as in Example 1.

[0070] The alkali content of the solid alkali catalyst prepared in this example is 6.512 mmol / g, and the yield of biomass fuel is 88.8%.

[0071] Example 6

[0072] The potassium nitrate solution in Example 1 was replaced with a lithium nitrate solution. The preparation method of the lithium nitrate solution was as follows: 1 g of lithium nitrate was dissolved in 2.5 mL of deionized water. Other conditions were the same as in Example 1.

[0073] The alkali content of the solid alkali catalyst prepared in this example is 10.56 mmol / g, and the yield of biomass fuel is 82.7%.

[0074] Example 7

[0075] The temperature of the reaction of methyl isobutyl ketone, furfural and solid base catalyst in Example 1 was modified to 130° C., and other conditions were the same as in Example 1.

[0076] The yield of the biomass fuel prepared in this example is 87.2%.

[0077] Example 8

[0078] The temperature of the reaction of methyl isobutyl ketone, furfural and solid base catalyst in Example 1 was modified to 150° C., and other conditions were the same as in Example 1.

[0079] The yield of the biomass fuel prepared in this example is 97.4%.

[0080] Example 9

[0081] The amount of the solid base catalyst in Example 1 was modified to 0.05 g, and the other conditions were the same as in Example 1.

[0082] The yield of the biomass fuel prepared in this example is 94.7%.

[0083] Example 10

[0084] The amount of the solid base catalyst in Example 1 was modified to 0.075 g, and the other conditions were the same as in Example 1.

[0085] The yield of the biomass fuel prepared in this example is 94.1%.

[0086] Embodiment 11

[0087] The amount of the solid base catalyst in Example 1 was modified to 0.15 g, and the other conditions were the same as in Example 1.

[0088] The yield of the biomass fuel prepared in this example is 96.3%.

[0089] Example 12

[0090] 0.002 mol of tannic acid, 0.01 mol of cerium chloride heptahydrate, 0.01 mol of zirconium oxychloride octahydrate and 80 mL of N,N-dimethylformamide were reacted at 70°C for 13 hours. The product was filtered and washed alternately with deionized water and anhydrous ethanol, the number of washings with deionized water and anhydrous ethanol were both 4 times, and then dried in an electric heated forced air drying oven at a temperature of 80°C for 5 hours to obtain a solid.

[0091] Put 2 g of solid into a round-bottom flask, heat it in an oil bath at 130°C for 5 h, lift the round-bottom flask, immediately add 80 mL of n-octane and plug it with a glass stopper, wait until the temperature of the oil bath drops to 40°C, re-immerse the round-bottom flask in the oil bath, then add lithium nitrate solution (the preparation method of lithium nitrate solution is: dissolve 1.25 g of potassium nitrate in 2.5 mL of deionized water) and soak for 13 h. After drying the impregnated product in an oil bath at 145°C for 8 h, transfer it to an electric heated forced air drying oven at 100°C and dry it for 5 h to obtain a precursor; calcine the precursor in a muffle furnace at 600°C for 12 h to obtain a solid base catalyst.

[0092] 1.8 mL of methyl isobutyl ketone, 0.3 mL of furfural and 0.12 g of a solid base catalyst were mixed evenly, and then reacted in an oil bath at a temperature of 150° C. for 5 hours. The product was centrifuged at a speed of 8500 rpm for 4 minutes to obtain biomass fuel.

[0093] The yield of the biomass fuel prepared in this example is 95.4%.

[0094] Example 13

[0095] 0.004 mol of tannic acid, 0.02 mol of cerium chloride heptahydrate, 0.02 mol of zirconium oxychloride octahydrate and 120 mL of N,N-dimethylformamide were reacted at 90°C for 11 hours. The product was filtered and washed alternately with deionized water and anhydrous ethanol, the number of washings with deionized water and anhydrous ethanol was 4 times each, and then dried in an electric heated forced air drying oven at a temperature of 100°C for 5 hours to obtain a solid.

[0096] Put 3 g of solid into a round-bottom flask, heat it in an oil bath at 135°C for 4 h, lift the round-bottom flask, immediately add 120 mL of n-octane and plug it with a glass stopper, wait until the temperature of the oil bath drops to 60°C, re-immerse the round-bottom flask in the oil bath, then add lithium nitrate solution (the preparation method of lithium nitrate solution is: dissolve 0.75 g of potassium nitrate in 2.5 mL of deionized water) and soak for 13 h. After drying the impregnated product in an oil bath at 155°C for 7.5 h, transfer it to an electric heated forced air drying oven at 140°C and dry it for 3 h to obtain a precursor; calcine the precursor in a muffle furnace at 800°C for 8 h to obtain a solid base catalyst.

[0097] 2.2 mL of methyl isobutyl ketone, 0.7 mL of furfural and 0.15 g of a solid base catalyst were mixed evenly, and then reacted in an oil bath at a temperature of 145° C. for 7 hours. The product was centrifuged at a speed of 9500 rpm for 2 minutes to obtain biomass fuel.

[0098] The yield of the biomass fuel prepared in this example is 91.5%.

[0099] Comparative Example 1

[0100] The potassium nitrate solution in Example 1 is replaced by a sodium nitrate solution. The preparation method of the sodium nitrate solution is as follows: dissolve 1 g of sodium nitrate in 2.5 mL of deionized water. Other conditions are the same as in Example 1.

[0101] The alkali amount of the solid alkali catalyst prepared in this comparative example is 3.072 mmol / g, and the yield of the biomass fuel is 2.1%.

[0102] Comparative Example 2

[0103] The potassium nitrate solution in Example 1 was replaced with a calcium nitrate solution. The preparation method of the calcium nitrate solution was as follows: 1 g of calcium nitrate tetrahydrate was dissolved in 2.5 mL of deionized water. Other conditions were the same as in Example 1.

[0104] The alkali amount of the solid alkali catalyst prepared in this comparative example is 5.056 mmol / g, and the yield of biomass fuel is 2.5%.

[0105] Comparative Example 3

[0106] The potassium nitrate solution in Example 1 is replaced by a magnesium nitrate solution. The preparation method of the magnesium nitrate solution is as follows: 1 g of magnesium nitrate hexahydrate is dissolved in 2.5 mL of deionized water. Other conditions are the same as in Example 1.

[0107] The alkali amount of the solid alkali catalyst prepared in this comparative example is 13.104 mmol / g, and the yield of biomass fuel is 2.8%.

[0108] Comparative Example 4

[0109] The potassium nitrate solution in Example 1 is replaced by a zinc nitrate solution. The preparation method of the zinc nitrate solution is as follows: 1 g of zinc nitrate hexahydrate is dissolved in 2.5 mL of deionized water. Other conditions are the same as in Example 1.

[0110] The alkali amount of the solid alkali catalyst prepared in this comparative example is 1.68 mmol / g, and the yield of the biomass fuel is 63.8%.

[0111] Comparative Example 5

[0112] The potassium nitrate solution in Example 1 was replaced with a lanthanum nitrate solution. The preparation method of the lanthanum nitrate solution was as follows: 1 g of lanthanum nitrate hexahydrate was dissolved in 2.5 mL of deionized water. Other conditions were the same as in Example 1.

[0113] The alkali amount of the solid alkali catalyst prepared in this comparative example is 1.616 mmol / g, and the yield of biomass fuel is 2%.

[0114] Comparative Example 6

[0115] The potassium nitrate solution in Example 1 is replaced by an aluminum nitrate solution. The preparation method of the aluminum nitrate solution is as follows: dissolve 1 g of aluminum nitrate nonahydrate in 2.5 mL of deionized water. Other conditions are the same as in Example 1.

[0116] The alkali amount of the solid alkali catalyst prepared in this comparative example is 1.44 mmol / g, and the yield of the biomass fuel is 1.8%.

[0117] Comparative Example 7

[0118] The temperature of the reaction of methyl isobutyl ketone, furfural and solid base catalyst in Example 1 was modified to 120° C., and other conditions were the same as in Example 1.

[0119] The yield of the biomass fuel prepared in this comparative example is 59.5%.

[0120] Comparative Example 8

[0121] The amount of the solid base catalyst in Example 1 was modified to 0.025 mg, and the other conditions were the same as in Example 1.

[0122] The yield of the biomass fuel prepared in this comparative example is 37.5%.

[0123] The invention uses tannic acid coordinated with cerium and zirconium as a carrier, supports metal nitrate by a double solvent impregnation method, and prepares a solid base catalyst with a large number of strong alkaline centers by roasting. The solid base catalyst has high specific surface area, low mass transfer resistance, high thermal stability, high catalytic activity, low preparation cost, and can be reused; it can effectively catalyze the condensation reaction of methyl isobutyl ketone and furfural, has high catalytic activity, and the catalytic reaction conditions are mild and controllable.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a solid base catalyst, characterized in that: The following steps are included: 1) reacting tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide to obtain a solid; 2) After heating the solid, adding n-octane, and then adding an alkali metal nitrate solution for impregnation, and drying the impregnated product to obtain a precursor; 3) calcining the precursor to obtain a solid base catalyst; Step 1) The reaction temperature is 70-90°C; Step 2) the heating temperature is 130-140°C; Step 2) the alkali metal nitrate solution is a potassium nitrate solution or a lithium nitrate solution; In the alkali metal nitrate solution, the mass volume ratio of alkali metal nitrate to solvent is 0.25~1.25g:2.5mL; The mass ratio of the solid to the alkali metal nitrate in the alkali metal nitrate solution is 1:0.1-0.5; Step 3) The calcination temperature is 600-800°C.

2. The preparation method according to claim 1, characterized in that: Step 1) The molar volume ratio of tannic acid, cerium chloride, zirconium oxychloride and N,N-dimethylformamide is 0.002-0.004 mol: 0.01-0.02 mol: 0.01-0.02 mol: 80-120 mL.

3. The preparation method according to claim 1 or 2, characterized in that: The reaction time of step 1) is 11 to 13 hours.

4. The preparation method according to claim 3, characterized in that: Step 2) The heating time is 4-6 hours; the immersion temperature is 40-60° C., and the immersion time is 11-13 hours.

5. The preparation method according to claim 4, characterized in that: Step 2) The mass volume ratio of the solid to n-octane is 2-3 g: 80-120 mL.

6. The preparation method according to claim 5, characterized in that: Step 2) the drying comprises a first drying and a second drying; The first drying temperature is 145~155℃, and the time is 7~8h; the second drying temperature is 100~140℃, and the time is 3~5h.

7. The preparation method according to claim 6, characterized in that: Step 3) The calcination time is 8 to 12 hours.

8. The solid base catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the solid base catalyst according to claim 8 in catalytic synthesis of biomass fuels, characterized in that: The following steps are included: Methyl isobutyl ketone, furfural and a solid base catalyst are mixed and reacted to obtain a biomass fuel; The volume mass ratio of the methyl isobutyl ketone, furfural and solid base catalyst is 1.8-2.2 mL: 0.3-0.7 mL: 0.05-0.15 g; The reaction temperature is 130-150° C., and the reaction time is 5-7 hours.

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