Preparation of bifunctional molecular sieve catalyst and method for applying bifunctional molecular sieve catalyst to oriented conversion of glucose into methyl levulinate

Abstract

The invention discloses preparation of a bifunctional molecular sieve catalyst and a method for applying the bifunctional molecular sieve catalyst to oriented conversion of glucose into methyl levulinate. According to the Zr-HY catalyst, simple dipping and high-temperature calcination are adopted, a metal component Zr with a Lewis acid site is introduced on the basis that a strong-acid HY molecular sieve serves as a Bronsted acid site, the bifunctional molecular sieve catalyst is prepared, and then the catalyst is applied to a reaction for preparing methyl levulinate through glucose alcoholysis. According to the method disclosed by the invention, an acid site is utilized, and a metal active site is introduced on the basis, so that the dehydration reaction activity can be improved, and an isomerization reaction from glucose to fructose can be effectively promoted. The catalyst has the characteristics of simplicity in preparation, economy, high catalytic activity, easiness in separation and the like, and shows good catalytic performance in a reaction for preparing methyl levulinate through glucose alcoholysis.

Description

[0001] The invention relates to the technical field of catalysts and applications, and in particular to a bifunctional molecular sieve catalyst 10% Zr-HY catalyst and a preparation method and application thereof. Background Art

[0002] Lignocellulosic biomass is abundant, widely distributed and cheap, and is a promising renewable bioresource that can be used to produce bio-based chemicals and value-added fuels. It is mainly composed of cellulose, hemicellulose and lignin. From these raw materials, a variety of high-value-added chemicals and fuels can be prepared through certain process methods. Among them, levulinic acid ester is a very important platform compound, which can be used in many fields such as perfume, organic solvents, adhesives, fuel additives and medicine.

[0003] At present, there are three main processes for preparing levulinic acid esters from biomass resources at home and abroad: 1) Levulinic acid esterification method. The advantage of this method is that the reaction is relatively easy to carry out and no by-products are produced, but the substrate levulinic acid must be synthesized by biomass conversion, resulting in its high cost; 2) Furfuryl alcohol hydrolysis method. This method can also obtain a relatively ideal yield for preparing levulinic acid esters, but the disadvantages are that the reaction load is complex, the energy consumption is high, and the conversion of furfural to furfuryl alcohol requires high-pressure hydrogenation, and the equipment requirements are also high; 3) Biomass direct alcoholysis method. Compared with the first two preparation processes, the biomass direct alcoholysis method shows great advantages. Its raw material source is wide, the process route is short and environmentally friendly, and it shows great prospects in industrial industrialization. The most critical one is the preparation of efficient and practical catalysts. At present, there are two types of catalytic systems for preparing levulinic acid esters. Among them, homogeneous catalytic systems such as liquid acids, metal salts and ionic liquids have good catalytic performance but obvious disadvantages, such as difficulty in separation and high corrosiveness. Heterogeneous catalytic systems have attracted more and more attention from researchers due to their advantages such as reusability, easy separation and recovery, and reduced environmental pollution. Among them, molecular sieves have the characteristics of low material cost, hydrothermal stability and large specific surface area, and show good performance in acid-catalyzed biomass utilization reactions.

[0004] The alcoholysis of glucose to prepare levulinate is a relatively complex reaction, which requires the synergistic action of Bronsted acid and Lewis acid. In order to achieve efficient alcoholysis of glucose, a bifunctional catalyst is the key to the entire reaction process. Summary of the invention

[0005] The present invention discloses a method for preparing a bifunctional molecular sieve catalyst and applying the catalyst to directional conversion of glucose into methyl levulinate. The purpose of the invention is to prepare a bifunctional catalyst which is beneficial to both dehydration reaction and isomerization reaction in view of the problems existing in the prior art, and the product and the catalyst are easy to separate, have high stability and can be recycled.

[0006] The technical solution of the present invention is a method for preparing a bifunctional molecular sieve catalyst and applying it to the directional conversion of glucose into methyl levulinate, which is characterized by comprising the following steps:

[0007] Place a certain concentration of zirconium oxychloride aqueous solution in a 250mL three-necked flask, then weigh a certain amount of HY molecular sieve and put it in, stir it magnetically for a certain period of time, vacuum dry it, put it in an oven, dry it to constant weight, grind it into powder and calcine it in a muffle furnace to obtain zirconium-doped HY molecular sieve. Add glucose, solvent and catalyst into a high-pressure reactor to form a reaction system, the amount of glucose added is 0.4g, the amount of catalyst used is 0.3g~0.5g, and the amount of methanol is 20mL.

[0008] 2. The preparation method according to claim 1, characterized in that the mass of HY molecular sieve is 2g.

[0009] 3. preparation method according to claim 1 is characterized in that, the stirring speed is 500rmp, and the time is 2h.

[0010] 4. The preparation method according to claim 1 is characterized in that the drying temperature is 105°C and the time is more than 12 hours.

[0011] 5. The preparation method according to claim 1, characterized in that the muffle furnace calcination temperature is 400-500°C.

[0012] 6. The preparation method according to claim 1, characterized in that the loading amount of Zr is 5% to 15%.

[0013] 7. An experiment in which the 10% Zr-HY catalyst prepared as claimed in claim 1 is used for preparing methyl levulinate by alcoholysis of glucose, characterized in that the experiment comprises the following steps.

[0014] 8. The bifunctional molecular sieve catalyst 10% Zr-HY catalyst, glucose, and solvent as claimed in claim 1 are added into a high-pressure reactor to form a reaction system, wherein the amount of glucose added is 0.4 g, the amount of catalyst used is 0.3 g to 0.5 g, and the amount of methanol used is 20 mL.

[0015] 9. Carry out the reaction at a temperature of 190-210°C for 1.5-3.5 hours. After the reaction is completed, separate the catalyst to obtain the target product.

[0016] 10. Advantages of the present invention: The bifunctional molecular sieve catalyst provided by the present invention has a simple preparation method, low material cost and high activity. Since the catalyst is a heterogeneous catalyst, it is easy to recycle and reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1Catalyst UV-visible absorption spectroscopy analysis (UV-vis)

[0018] Figure 2 Catalyst pyridine infrared spectrum (Py-FTIR)

[0019] Figure 3 Stability test of catalyst 10% Zr-HY DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the claims attached to the application.

[0021] Implementation Case 1

[0022] Weigh 0.4 g of glucose, 0.4 g of 10% Zr-HY catalyst, and 20 mL of methanol in a high-pressure reactor, react at 200°C for 2.5 h. After the reaction is completed, cool to room temperature, and analyze the products by gas phase and liquid phase respectively. The glucose conversion rate is calculated by quantitative analysis to be 100%, and the yields of methyl levulinate and levulinic acid are 43%.

[0023] Implementation Case 2

[0024] The reaction steps are exactly the same as those in Example 1, except that 5% Zr-HY is prepared in the catalyst preparation step. The glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 31.7%.

[0025] Implementation Case 3

[0026] The reaction steps are exactly the same as those in Example 1, except that 15% Zr-HY is prepared in the catalyst preparation step. The glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 34.6%.

[0027] Implementation Case 4

[0028] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the glucose alcoholysis reaction time is 1.5 h, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 36.7%.

[0029] Implementation Case 5

[0030] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the glucose alcoholysis reaction time is 2 h, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 38.4%.

[0031] Implementation Case 6

[0032] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the glucose alcoholysis reaction time is 3 h, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 41%.

[0033] Implementation Case 7

[0034] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the glucose alcoholysis reaction time is 3.5 h, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 40.2%.

[0035] Implementation Case 8

[0036] The catalyst preparation is exactly the same as that in Example 1, except that in the reaction step, the glucose alcoholysis reaction temperature is 190° C., the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 36.6%.

[0037] Implementation Case 9

[0038] The catalyst preparation is exactly the same as that in Example 1, except that in the reaction step, the glucose alcoholysis reaction temperature is 195° C., the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 40.5%.

[0039] Implementation Case 10

[0040] The catalyst preparation is exactly the same as that in Example 1, except that in the reaction step, the glucose alcoholysis reaction temperature is 205° C., the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 40.5%.

[0041] Implementation Case 11

[0042] The catalyst preparation is exactly the same as that in Example 1, except that in the reaction step, the glucose alcoholysis reaction temperature is 210° C., the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 34.2%.

[0043] Implementation Case 12

[0044] The catalyst preparation is exactly the same as that in Implementation Example 1, except that: in the reaction step, the amount of catalyst used in the glucose alcoholysis reaction is 0.3 g, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 30.3%.

[0045] Implementation Case 13

[0046] The catalyst preparation is exactly the same as that in Implementation Example 1, except that: in the reaction step, the amount of catalyst used in the glucose alcoholysis reaction is 0.35 g, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 31.5%.

[0047] Implementation Case 14

[0048] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the amount of catalyst used in the glucose alcoholysis reaction is 0.45 g, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 41%.

[0049] Implementation Case 15

[0050] The catalyst preparation is exactly the same as that in Example 1, except that: in the reaction step, the amount of catalyst used in the glucose alcoholysis reaction is 0.5 g, the glucose conversion rate is 100%, and the yield of the main products methyl levulinate and levulinic acid is 37.3%.

[0051] Figure 1 This is a UV-vis graph of the bifunctional molecular sieve catalyst prepared in Example 1. It can be seen from the figure that the catalyst is in a crystalline state.

[0052] Figure 2 This is the infrared spectrum of the catalyst pyridine, which shows the spectrum at 1445cm -1 、1490cm -1 and 1540cm -1 There are several characteristic peaks at 1445cm -1 The characteristic peak at 1540cm belongs to the Lewis acid site and is the result of the interaction between Zr and the non-framework aluminum of the parent HY zeolite octahedron. -1 The characteristic peak at is provided by the tetrahedral framework aluminum on the zeolite HY matrix. Acid position. 1490cm -1 The characteristic peaks at are derived from the interaction between pyridine molecules and Lewis and Interaction of acid sites.

[0053] Figure 3 This is a stability test of the catalyst prepared in Example 1. After repeating three times, the yield of methyl levulinate can still be maintained at about 20%.

[0054] Table 1 shows the effect of the bifunctional molecular sieve catalyst prepared in Examples 1-3 on the glucose alcoholysis reaction. It can be seen from Table 1 that the best reaction effect is achieved when the metal loading is 10%.

[0055] Table 2 shows the effects of different reaction times on implementation case 1 and implementation cases 4-7. It can be seen from the table that when the reaction time is 2.5 h, the catalyst performance is the best, the glucose conversion rate is 100%, and the yields of levulinic acid and methyl levulinate are 43%.

[0056] Table 3 shows the effects of different reaction temperatures on implementation case 1 and implementation cases 8-11. It can be seen from the table that when the reaction time is 200°C, the catalyst performance is the best.

[0057] Table 4 shows the effects of different catalyst dosages on implementation case 1 and implementation cases 12-15. It can be seen from the table that when the catalyst dosage is 0.4 g, the catalyst performance is the best.

[0058] Table 1 shows the reaction effects of glucose alcoholysis under different metal loadings in implementation cases 1 to 3.

[0059]

[0060] Table 2 shows the impact of different reaction times for implementation cases 1 and 4-7.

[0061]

[0062] Table 3 shows the effects of different reaction temperatures on implementation cases 1 and 8-11.

[0063]

[0064] Table 4 shows the effects of different catalyst dosages on implementation case 1 and implementation cases 12-15.

[0065]

[0066] The above embodiments are the implementation modes adopted by the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a bifunctional molecular sieve catalyst and applying it to the directional conversion of glucose into methyl levulinate, characterized in that: The catalyst is based on the strong acid HY molecular sieve as the Bronsted acid site, and Zr metal is added which is beneficial to the isomerization reaction. It is prepared by stirring and mixing at room temperature and metal impregnation. The preparation method is as follows: A certain concentration of zirconium oxychloride aqueous solution is placed in a 250 mL flask, and a certain amount of HY molecular sieve is weighed and placed therein. After magnetic stirring for a certain period of time, the solution is vacuum dried, placed in an oven, dried to constant weight, ground into powder, and calcined in a muffle furnace to obtain zirconium-doped HY molecular sieve.

2. The preparation method according to claim 1, characterized in that: The mass of HY molecular sieve is 2g.

3. The preparation method according to claim 1, characterized in that: The stirring speed was 500 rpm and the time was 2 h.

4. The preparation method according to claim 1, characterized in that: The drying temperature is 105°C and the drying time is more than 12 hours.

5. The preparation method according to claim 1, characterized in that: The calcination temperature in the muffle furnace is 400-500°C.

6. The preparation method according to claim 1, characterized in that: The loading amount of Zr is 5% to 15%.

7. A method for preparing methyl levulinate by catalyzing the alcoholysis of glucose, characterized in that: Glucose alcoholysis reaction is achieved by using biomass derivatives such as glucose as substrates, methanol as solvent, and the bifunctional molecular sieve catalyst according to claim 1 as a reaction catalyst.

8. The method according to claim 7, characterized in that When glucose is used as the substrate, the preparation steps include the following: adding glucose, the bifunctional molecular sieve catalyst and methanol into a high-pressure reactor, the reaction temperature is 190° C.-210° C., and the reaction time is 1.5-3.5 hours.

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