Continuous preparation method of supported catalyst and application of supported catalyst in catalysis of furfural hydrocracking

Abstract

The invention relates to a continuous preparation method of a supported catalyst and application of the supported catalyst in catalysis of furfural hydrocracking. The method comprises the following steps: adding Cu (NO3) 2.3 H2O, Ce (NO3) 3.6 H2O, Mg (NO3) 2.6 H2O and Al (NO3) 3.9 H2O into deionized water to form a solution A; naOH and Na2CO3 are taken and dissolved in deionized water, and a solution B is formed; then respectively introducing the solution A and the solution B into a feeding pump, then introducing into a membrane dispersion microreactor, and mixing to form a precipitate; and washing, drying, calcining and reducing to obtain the catalyst Cu-Ce / MgO-Al2O3. The catalyst prepared by the invention is used in a reaction for catalyzing furfural hydrocracking to prepare 1, 2-pentanediol, and shows excellent catalytic activity and stability, the conversion rate of furfural is as high as 99%, and the yield of 1, 2-pentanediol reaches 44%.

Description

Technical Field

[0001] This invention relates to a method for preparing pentanediol by hydrogenation cracking of furfural using a supported catalyst, and particularly to the preparation of 1,2-pentanediol by hydrogenation cracking of furfural using a multi-active component catalyst. Background Technology

[0002] Faced with the dual challenges of dwindling traditional fossil resources and increasing environmental pressure, developing and utilizing biomass resources has become an inevitable choice for achieving sustainable development goals. Furfural, as an important biomass resource, can be converted into high-value-added products through catalytic hydrogenation, such as 1,2-pentanediol, 2-methylfuran, cyclopentanone, and 1,5-pentanediol. Among these, 1,2-pentanediol has important applications in polyester polyols, solvents, and humectants. In industry, 1,2-pentanediol is used as a green solvent in electronic cleaning and ink processing; in food and agriculture, it serves as a safe humectant and pesticide emulsifier; in cosmetics, it is widely used as a humectant and solvent in emulsions and sunscreens, replacing traditional glycerin; in the pharmaceutical industry, it is used as a drug carrier or transdermal absorption enhancer and participates in the synthesis of antibiotic intermediates. In the field of polymer materials, it is used in the reaction with isocyanates to prepare polyurethane elastomers.

[0003] Currently, there are two main types of catalysts for the highly selective preparation of pentanediol from furfural. One type is noble metal catalysts such as Pt, Pd, Ru, and Rh, but their high price significantly affects production costs. The other type is non-noble metal-based catalysts such as Ni, Cu, and Co, which are inexpensive but have complex preparation processes and poor catalytic performance. Weng Yujing et al. (Journal of Fuel Chemistry and Technology, 2021, 49(12): 1867-1874.) used a Ru / MnO catalyst to catalyze the hydrogenation cracking of furfural to prepare 1,2-pentanediol, achieving a furfural conversion rate of 100% and a 1,2-pentanediol yield of 32%. Using noble metal catalysts results in higher 1,2-pentanediol yields, but noble metal catalysts suffer from high costs. Patrick et al. (RSCA Advances, 2020, 10(46): 27323-27330.) synthesized a nickel-modified tungsten carbide (Ni / WC / SiO2) catalyst by impregnation. However, the preparation of the SiO2 support required calcination at 700℃ for 8 h followed by loading of tungsten and subsequent calcination at 450℃ for 6 h, making the catalyst preparation process complex and time-consuming. The catalyst was used in the furfural hydrogenation reaction, where the yield of 1,2-pentanediol was 21%. Liang Yongjia et al. (Catalysis Letters, 2024, 154(11): 5745-5756.) prepared a metal catalyst CuCo / La by co-precipitation. However, the preparation required controlling a stable pH and aging for 24 h to obtain the catalyst precursor. The catalyst was used in the furfural hydrogenation reaction, where the yield of 1,2-pentanediol was 21.70%. The yield of 1,2-pentanediol using non-precious metal catalysts is low, and the above non-precious metal-based catalysts have problems such as poor catalytic performance and complex preparation processes.

[0004] Therefore, developing more efficient, stable, and low-cost catalysts, optimizing reaction conditions and processes, and improving reaction selectivity and yield to achieve the efficient preparation of 1,2-pentanediol from furfural via catalytic hydrogenation has significant application value. Summary of the Invention

[0005] The purpose of this invention is to address the limitations of current technologies by proposing a continuous preparation method for supported copper-based catalysts and their application in the catalytic hydrogenation cracking of furfural. This method utilizes the precise microporous membrane structure of a membrane dispersion microreactor to achieve efficient mixing of reaction precursors, enabling rapid and controllable nucleation and growth of the metal salt solution and precipitant solution. This achieves continuous preparation of nanoscale catalysts, significantly shortening the catalyst preparation time and making the preparation process more green and efficient. The catalyst prepared by this invention exhibits excellent catalytic activity and stability in the catalytic hydrogenation cracking of furfural to 1,2-pentanediol, achieving a furfural conversion rate of up to 99% and a 1,2-pentanediol yield of 44%.

[0006] The technical solution of this invention is as follows:

[0007] A continuous preparation method for a supported catalyst, the method comprising the following steps:

[0008] 1) Add Cu(NO3)2·3H2O, Ce(NO3)3·6H2O, Mg(NO3)2·6H2O, and Al(NO3)3·9H2O to deionized water to form solution A; separately dissolve NaOH and Na2CO3 in deionized water to form solution B;

[0009] In solution A, 0.005-0.011 mol Cu(NO3)2·3H2O, 0.0007-0.005 mol Ce(NO3)3·6H2O, 0.02-0.035 mol Mg(NO3)2·6H2O, and 0.005-0.02 mol Al(NO3)3·9H2O are added to every 150 mL of deionized water.

[0010] In solution B, add 0.040-0.125 mol NaOH and 0.02-0.075 mol Na2CO3 to every 150 mL of deionized water;

[0011] 2) Solution A and solution B are fed into the feed pumps respectively, and then fed into the membrane dispersion microreactor at 20-50℃. After mixing, the mixture is kept in the residence tube for 1-10 min to form a precipitate. The precipitate is centrifuged and washed until the pH is neutral, dried and ground to obtain the catalyst precursor Cu-Ce / MgO-Al2O3. Finally, it is calcined in air at 400-600℃ and reduced in a hydrogen atmosphere at 400-600℃ to obtain the catalyst Cu-Ce / MgO-Al2O3.

[0012] In this process, solutions A and B are introduced into the membrane dispersion microreactor at a flow rate ratio of 1:0.5-1.5.

[0013] The flow rate of solution A is 1-15 ml / min;

[0014] In the membrane dispersion microreactor, the stainless steel microfiltration membrane has a pore size of 0.5-5μm and a diameter of 6.5-100mm; the residence tube is made of polytetrafluoroethylene, with an inner diameter of 1.5-2.5mm and a length of 0.5-100m.

[0015] In step 1), Cu(NO3)2·3H2O is preferably 0.008 mol, Ce(NO3)3·6H2O is preferably 0.002 mol, Mg(NO3)2·6H2O is preferably 0.027 mol, Al(NO3)3·9H2O is preferably 0.013 mol, NaOH is preferably 0.075 mol, and Na2CO3 is preferably 0.045 mol.

[0016] In step 2), the preferred flow rate is 5 mL / min.

[0017] The calcination temperature of a catalyst affects its specific surface area and pore size. With a calcination temperature of 400-550℃, the specific surface area and pore size initially increase and then decrease as the temperature rises. The maximum specific surface area (288.42 m²) is reached at a calcination temperature of 500℃. 2 / g, average pore size 21.78nm.

[0018] The supported catalyst comprises an active component and a support, wherein the support is magnesium oxide and aluminum oxide, and the active component is a main metal M1 or a main metal M1 and a cofactor M2; the molar ratio of the active component to the support is 1:4-20; the molar ratio of the main metal M1 to the cofactor M2 is 1:0.1-0.7.

[0019] The main metal M1 of the catalyst is Cu;

[0020] The catalyst's promoter M2 is Ce;

[0021] The application of the catalyst prepared by the method in the catalytic hydrogenation cracking of furfural includes the following steps:

[0022] Furfural, isopropanol, and a supported catalyst are added to a batch high-pressure reactor. Then, the air in the reactor is replaced with N2, followed by H2. The reactor is then reacted at an H2 pressure of 3-6 MPa and a temperature of 140-170 °C for 5.5-7 h, resulting in catalytic hydrogenation cracking to obtain 1,2-pentanediol.

[0023] The mass ratio of furfural to catalyst is 100:3:1; the molar ratio of furfural to isopropanol is 1:0:50. When the material ratio is 0, it means that this substance is not added.

[0024] The essential features of this invention are:

[0025] This invention provides a continuous preparation method for supported catalysts based on a membrane-dispersed microreactor, which overcomes the limitations of traditional batch preparation processes. By controlling the preparation process conditions, the metal salt solution is allowed to pass through the microfiltration membrane in the form of an extremely fine stream, and then instantly and rapidly mixes with the longitudinally precipitating agent at a uniform and rapid pace. This achieves precise control over the nucleation and growth process of nanoparticles, thereby completing the continuous preparation of nanoscale catalysts. This method is simple, economical, pollution-free, and significantly shortens the catalyst preparation time.

[0026] This invention employs a heterogeneous catalyst with a supported structure of MgO and Al2O3 supporting Cu and Ce bimetallic molecules. The close synergistic effect between the active copper species and the support induces the directional adsorption of the intermediate furfuryl alcohol molecule on the catalyst surface. The strong interaction between the active co-metal Ce and the support components not only enhances the catalyst's redox performance but also modifies the acid-base sites on the catalyst surface. The basic sites significantly promote the ring-opening of furfuryl alcohol by stabilizing the reaction intermediate, thereby improving product selectivity.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention provides a method for synthesizing 1,2-pentanediol from furfural. The method employs a non-precious metal heterogeneous solid catalyst, and the preferred catalytic reaction conditions are a reaction temperature of 160°C, an H2 pressure of 6 MPa, a reaction time of 5.5 h, and a catalyst concentration of 30%. The furfural conversion rate reaches 99%, and the 1,2-pentanediol yield reaches 44%. The catalyst can be recycled five times while maintaining excellent catalytic performance.

[0029] This invention prepares supported copper-based catalysts using a membrane dispersion microreactor and employs non-precious metals as the active component. This method allows for the continuous preparation of monolithically formed supported catalyst precursors with a large specific surface area, high dispersibility, and a simple and environmentally friendly preparation process. Furthermore, it demonstrates good catalytic performance and stability in the catalytic hydrogenation cracking of furfural to 1,2-pentanediol, showing promising application prospects. Attached Figure Description

[0030] Figure 1 XRD patterns of the catalysts prepared in Examples 1 and 2

[0031] Figure 2 XRD patterns of the catalysts prepared in Examples 2, 11, and 13.

[0032] Figure 3 The N2- adsorption-desorption isotherms of the catalysts prepared in Examples 1, 2, 11, and 13.

[0033] Figure 4 The pore size distribution diagrams are of the catalysts prepared in Examples 1, 2, 11, and 13.

[0034] Figure 5 TEM images of the catalysts prepared in Examples 1, 2, 11, and 13. Detailed Implementation

[0035] The invention will be further illustrated with examples of its implementation.

[0036] The membrane dispersion microreactor involved in this invention specifically comprises a stainless steel microfiltration membrane with a pore size of 1 μm, a diameter of 1.6 mm, and a thickness of 6 mm; the residence tube is made of polytetrafluoroethylene with an inner diameter of 2 mm and a length of 15 m. However, it is not limited to this.

[0037] Example 1: Preparation of 10-Cu / MgO-Al2O3-500-500

[0038] 0.01 mol Cu(NO3)2·3H2O, 0.027 mol Mg(NO3)2·6H2O, and 0.013 mol Al(NO3)3·9H2O were dissolved in 150 mL of deionized water to form solution A; 0.075 mol NaOH and 0.045 mol Na2CO3 were dissolved in 150 mL of deionized water to form solution B; solutions A and B were fed into the feed pump at a flow rate of 5 mL / min (total flow rate 10 mL / min), and mixed in a membrane dispersion microreactor at 30 °C to form a precipitate; the precipitate was centrifuged and washed until the pH was neutral, dried in an oven at 80 °C for 3 h, ground to obtain the catalyst precursor, and then calcined in a muffle furnace at 500 °C for 3 h, and reduced in a tube furnace at 500 °C under H2 atmosphere for 3 h to obtain catalyst 10-Cu / MgO-Al2O3-500-500.

[0039] Example 2: Preparation of 10-8Cu-2Ce / MgO-Al2O3-500-500

[0040] 0.008 mol Cu(NO3)2·3H2O, 0.002 mol Ce(NO3)3·6H2O, 0.027 mol Mg(NO3)2·6H2O, and 0.013 mol Al(NO3)3·9H2O were dissolved in 150 mL of deionized water to form solution A; 0.075 mol NaOH and 0.045 mol Na2CO3 were dissolved in 150 mL of deionized water to form solution B; solutions A and B were fed into the feed pump at a flow rate of 5 mL / min and mixed in a membrane dispersion microreactor at 30 °C to form a precipitate; the precipitate was centrifuged and washed until the pH was neutral, dried in an oven at 80 °C for 3 h, ground to obtain the catalyst precursor, and then calcined in a muffle furnace at 500 °C for 3 h, and reduced in a tube furnace at 500 °C under H2 atmosphere for 3 h to obtain catalyst 10-8Cu-2Ce / MgO-Al2O3-500-500.

[0041] Depend on Figure 1 XRD patterns and Figure 5The TEM images (a) and (b) show the analysis of the catalysts obtained in Examples 1 and 2. It can be seen that when the rare earth element Ce is introduced into the catalyst, the intensity of the characteristic diffraction peak of Cu at 2θ = 43.3° significantly decreases while the full width at half maximum (FWHM) significantly increases. This indicates that the catalyst's dispersibility is significantly enhanced, and the average particle size of the metal particles decreases. This demonstrates that the incorporation of Ce effectively inhibits the growth process of Cu grains, thereby significantly improving the dispersibility of copper species on the catalyst support surface.

[0042] Examples 3-6: Preparation of 10-10Cu-Ce / MgO-Al2O3-500-500, 10-9Cu-Ce / MgO-Al2O3-500-500, 10-7Cu-3Ce / MgO-Al2O3-500-500, and 10-6Cu-4Ce / MgO-Al2O3-500-500

[0043] The other steps are the same as in Example 2, except that the molar ratios of Cu(NO3)2·3H2O and Ce(NO3)3·6H2O are 10:1, 9:1, 7:3, and 6:4, respectively, with the total molar amounts of copper and cerium being the same. Ultimately, four different catalysts were obtained: 10-10Cu-Ce / MgO-Al2O3-500-500, 10-9Cu-Ce / MgO-Al2O3-500-500, 10-7Cu-3Ce / MgO-Al2O3-500-500, and 10-6Cu-4Ce / MgO-Al2O3-500-500.

[0044] The catalyst is represented by R-xM1-yM2 / MgO-Al2O3-ab, where R represents the total flow rate, M1 represents the main metal, M2 represents the auxiliary metal, x and y represent the proportion of M1 and M2 in the total molar amount of the catalyst, a represents the calcination temperature of the catalyst, and b represents the reduction temperature of the catalyst.

[0045] Example 7: Preparation of 5-8Cu-2Ce / MgO-Al2O3-500-500

[0046] 0.008 mol Cu(NO3)2·3H2O, 0.002 mol Ce(NO3)3·6H2O, 0.027 mol Mg(NO3)2·6H2O, and 0.013 mol Al(NO3)3·9H2O were dissolved in 150 mL of deionized water to form solution A; 0.075 mol NaOH and 0.045 mol Na2CO3 were dissolved in 150 mL of deionized water to form solution B; solutions A and B were fed into a feed pump at a flow rate of 2.5 mL / min and mixed in a membrane dispersion microreactor at 30 °C to form a precipitate; the precipitate was centrifuged and washed until the pH was neutral, dried in an oven at 80 °C for 3 h, ground to obtain the catalyst precursor, and then calcined in a muffle furnace at 500 °C for 3 h, and reduced in a tube furnace at 500 °C under H2 atmosphere for 3 h to obtain catalyst 5-8Cu-2Ce / MgO-Al2O3-500-500.

[0047] Examples 8-10: Preparation of 15-8Cu-2Ce / MgO-Al2O3-500-500, 20-8Cu-2Ce / MgO-Al2O3-500-500, and 25-8Cu-2Ce / MgO-Al2O3-500-500

[0048] The other steps are the same as in Example 7, except that the solution flow rate is changed to 7.5 ml / min, 10 ml / min, and 12.5 ml / min respectively (changing the tube length to keep the residence time in the tube constant). Finally, three different materials were obtained: 15-8Cu-2Ce / MgO-Al2O3-500-500, 20-8Cu-2Ce / MgO-Al2O3-500-500, and 25-8Cu-2Ce / MgO-Al2O3-500-500 catalysts. Example 11: Preparation of 10-8Cu-2Ce / MgO-Al2O3-400-500

[0049] 0.008 mol Cu(NO3)2·3H2O, 0.002 mol Ce(NO3)3·6H2O, 0.027 mol Mg(NO3)2·6H2O, and 0.013 mol Al(NO3)3·9H2O were dissolved in 150 mL of deionized water to form solution A; 0.075 mol NaOH and 0.045 mol Na2CO3 were dissolved in 150 mL of deionized water to form solution B; solutions A and B were fed into the feed pump at a flow rate of 5 mL / min and mixed in a membrane dispersion microreactor at 30 °C to form a precipitate; the precipitate was centrifuged and washed until the pH was neutral, dried in an oven at 80 °C for 3 h, ground to obtain the catalyst precursor, and then calcined in a muffle furnace at 400 °C for 3 h, and reduced in a tube furnace at 500 °C under H2 atmosphere for 3 h to obtain catalyst 10-8Cu-2Ce / MgO-Al2O3-400-500.

[0050] Examples 12-14: Preparation of 10⁻⁸Cu₂Ce / MgO-Al₂O₃-450-500, 10⁻⁸Cu₂Ce / MgO-Al₂O₃-550-500, and 10⁻⁸Cu₂Ce / MgO-Al₂O₃-600-500

[0051] The other steps are the same as in Example 11, except that the calcination temperature in air is changed to 450℃, 550℃, and 600℃, respectively. Finally, three different materials were obtained: 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-450-500, 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-550-500, and 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-600-500 catalysts.

[0052] Depend on Figure 2 XRD patterns and Figure 5 Analysis of the catalysts obtained in Examples 2, 11, and 13 using TEM images (b), (c), and (d) shows that the characteristic diffraction peaks of the active components Cu(111) and (200) crystal planes at 2θ (43.3° and 50.4°) are highly dispersed. When the calcination temperature increases from 400℃ to 550℃, the average particle size of the catalyst is smallest at 500℃. This indicates that a suitable calcination temperature facilitates the rearrangement and diffusion of copper species, while excessively high calcination temperatures can cause metal particle sintering and agglomeration, thus affecting the catalyst's performance.

[0053] like Figure 3Analysis of the N2- adsorption-desorption isotherms of the catalysts obtained in Examples 1, 2, 11, and 13 shows that the curves conform to the typical characteristics of type IV isothermal adsorption curves, indicating the presence of a mesoporous structure in the catalysts. Catalyst 10-Cu / MgO-Al2O3-500-500 exhibits the lowest adsorption capacity, suggesting a relatively simple pore structure and concentrated pore size distribution. However, after the introduction of Ce, catalyst 10-8Cu-2Ce / MgO-Al2O3-500-500 shows the highest adsorption capacity, indicating a more complex pore structure, wider pore size distribution, and the presence of more mesopores and macropores, exhibiting the best pore structure and adsorption performance.

[0054] Table 1. Specific surface area and average pore size of catalyst 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-a⁻⁵⁰.

[0055]

[0056] Depend on Figure 4 The catalyst pore size distribution diagram and the data in Table 1 show that the specific surface area of ​​the catalyst significantly increases and the average pore size decreases after Ce is introduced. During the calcination temperature range of 400-550℃, the specific surface area and pore size of the catalyst initially increase and then decrease as the temperature rises. The maximum specific surface area of ​​288.42 m² is reached at a calcination temperature of 500℃. 2 / g, average pore size 21.78nm.

[0057] Example 15: Preparation of 10-8Cu-2Ce / MgO-Al2O3-500-450

[0058] 0.008 mol Cu(NO3)2·3H2O, 0.002 mol Ce(NO3)3·6H2O, 0.027 mol Mg(NO3)2·6H2O, and 0.013 mol Al(NO3)3·9H2O were dissolved in 150 mL of deionized water to form solution A; 0.075 mol NaOH and 0.045 mol Na2CO3 were dissolved in 150 mL of deionized water to form solution B; solutions A and B were fed into the feed pump at a flow rate of 5 mL / min, and mixed in a membrane dispersion microreactor at 30 °C to form a precipitate; the precipitate was centrifuged and washed until the pH was neutral, dried in an oven at 80 °C for 3 h, ground to obtain the catalyst precursor, and then calcined in a muffle furnace at 500 °C for 3 h, and reduced in a tube furnace at 450 °C under H2 atmosphere for 3 h to obtain the catalyst 10-8Cu-2Ce / MgO-Al2O3-500-450.

[0059] Examples 16-18: Preparation of 10⁻⁸Cu₂Ce / MgO-Al₂O₃-500-400, 10⁻⁸Cu₂Ce / MgO-Al₂O₃-500-550, and 10⁻⁸Cu₂Ce / MgO-Al₂O₃-500-600

[0060] The other steps are the same as in Example 15, except that the reduction temperature in hydrogen is changed to 400℃, 550℃, and 600℃, respectively. Ultimately, three different materials were obtained: 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-500-400, 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-400-550, and 10⁻⁸Cu⁻²Ce / MgO-Al₂O₃-500-600 catalysts.

[0061] Example 19: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0062] 2.1 mmol (0.2 g) of furfural was added to a batch high-pressure reactor, followed by 130 mmol of isopropanol. 0.05 g of the catalyst obtained in Example 1 was added to the reactor, which was then sealed. The air inside the reactor was then replaced five times with N2, followed by five times with H2. The reaction was then carried out at an H2 pressure of 4 MPa and a temperature of 160 °C for 6.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the filtered supernatant was subjected to qualitative analysis. The furfural conversion rate was 99.90%, and the selectivity for 1,2-pentanediol was 32.79%.

[0063] Example 20: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0064] 2.1 mmol (0.2 g) of furfural was added to a batch high-pressure reactor, followed by 130 mmol of isopropanol. 0.05 g of the catalyst obtained in Examples 2-6 was added to the reactor, which was then sealed. The air inside the reactor was then replaced with N2 five times, followed by H2 five times. The reaction was then carried out at an H2 pressure of 4 MPa and a temperature of 160 °C for 6.5 h. After the reaction was completed, the supernatant was cooled to room temperature and filtered for qualitative analysis. The reaction results are shown in Table 2.

[0065] Table 2. Effect of the ratio of main metal copper to auxiliary metal cerium on the reaction.

[0066]

[0067] As shown in Table 2, as the Cu / Ce molar ratio changes from 10:1 to 6:4, the selectivity of the catalyst for furfuryl alcohol first decreases and then increases, while the selectivity of the product 1,2-pentanediol first increases and then decreases. When the Cu / Ce ratio is 8:2, the catalyst 10-8Cu-2Ce / MgO-Al2O3-500-500 exhibits the best catalytic performance.

[0068] Example 21: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0069] 2.1 mmol (0.2 g) of furfural was added to a batch high-pressure reactor, followed by 130 mmol of isopropanol. 0.05 g of the catalyst obtained in Examples 2 and 7-10 was added to the reactor, which was then sealed. The air inside the reactor was then replaced with N2 five times, followed by H2 five times. The reaction was then carried out at an H2 pressure of 4 MPa and a temperature of 160 °C for 6.5 h. After the reaction was completed, the reactor was cooled to room temperature, and the filtered supernatant was subjected to qualitative analysis. The reaction results are shown in Table 3.

[0070] Table 3 Effect of total flow rate on the reaction

[0071]

[0072] As shown in Table 3, the yield of 1,2-pentanediol first increased and then decreased as the total flow rate of metal salt and precipitant increased from 5 mL / min to 25 mL / min; the catalyst showed the highest selectivity for 1,2-pentanediol when the total flow rate was 10 mL / min.

[0073] Example 22: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0074] 2.1 mmol (0.2 g) of furfural was added to a batch high-pressure reactor, followed by 130 mmol of isopropanol. 0.05 g of the catalyst obtained in Examples 2 and 11-14 was added to the reactor, which was then sealed. The air inside the reactor was then replaced with N2 five times, followed by H2 five times. The reaction was then carried out at an H2 pressure of 4 MPa and a temperature of 160 °C for 6.5 h. After the reaction was completed, the reactor was cooled to room temperature, and the filtered supernatant was subjected to qualitative analysis. The reaction results are shown in Table 4.

[0075] Table 4 Effect of calcination temperature on the reaction

[0076]

[0077] As can be seen from the data in Table 4, the hydrogenation performance of the catalyst increases when the calcination temperature increases to 500℃; however, further increasing the calcination temperature to 600℃ reduces the catalytic performance of the catalyst, and the preferred calcination temperature is 500℃.

[0078] Example 23: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0079] 2.1 mmol (0.2 g) of furfural was added to a batch high-pressure reactor, followed by 130 mmol of isopropanol. 0.05 g of the catalyst obtained in Examples 2 and 15-18 was added to the reactor, which was then sealed. The air inside the reactor was then replaced with N2 five times, followed by H2 five times. The reaction was then carried out at an H2 pressure of 4 MPa and a temperature of 160 °C for 6.5 h. After the reaction was completed, the reactor was cooled to room temperature, and the filtered supernatant was subjected to qualitative analysis. The reaction results are shown in Table 5.

[0080] Table 5 Effect of reduction temperature on the reaction

[0081]

[0082] As shown in Table 5, the hydrogenation performance of the catalyst gradually improves with increasing reduction temperature; however, when the reduction temperature is further increased to 600℃, the hydrogenation performance of the catalyst decreases significantly. The preferred reduction temperature is 500℃.

[0083] Example 24: Preparation of 1,2-pentanediol by hydrogenation cracking of furfural

[0084] 21 mmol (2.0 g) of furfural was added to a batch high-pressure reactor, followed by 17 mmol of isopropanol. 0.6 g of the catalyst obtained in Example 2 was added to the reactor, which was then sealed. The air inside the reactor was then replaced five times with N2, followed by five times with H2. The reaction was then carried out at an H2 pressure of 6 MPa and a temperature of 160 °C for 5.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the filtered supernatant was subjected to qualitative analysis. The furfural conversion rate was 99.89%, and the selectivity for 1,2-pentanediol was 44.62%.

[0085] Matters not covered in this invention are common knowledge.

Claims

1. A continuous preparation method for a supported catalyst, characterized in that the method comprises the following steps: 1) Add Cu(NO3)2·3H2O, Ce(NO3)3·6H2O, Mg(NO3)2·6H2O, and Al(NO3)3·9H2O to deionized water to form solution A; separately dissolve NaOH and Na2CO3 in deionized water to form solution B; in, In solution A, add 0.005-0.011 mol Cu(NO3)2·3H2O, 0.0007-0.005 mol Ce(NO3)3·6H2O, 0.02-0.035 mol Mg(NO3)2·6H2O, and 0.005-0.02 mol Al(NO3)3·9H2O to every 150 mL of deionized water. In solution B, add 0.040-0.125 mol NaOH and 0.02-0.075 mol Na2CO3 to every 150 mL of deionized water; 2) At 20-50℃, solutions A and B are fed into the feed pumps respectively, and then into the membrane dispersion microreactor. After mixing, the mixture is kept in the residence tube for 1-10 min to form a precipitate. The precipitate is centrifuged and washed until the pH is neutral, dried and ground to obtain the catalyst precursor Cu-Ce / MgO-Al2O3. Finally, it is calcined in air at 400-600℃ and reduced in a hydrogen atmosphere at 400-600℃ to obtain the supported catalyst Cu-Ce / MgO-Al2O3. In this process, solutions A and B are introduced into the membrane dispersion microreactor at a flow rate ratio of 1:0.5-1.

5.

2. The continuous preparation method of the supported catalyst as described in claim 1, characterized in that, The flow rate of solution A is 1-15 ml / min.

3. The continuous preparation method of the supported catalyst as described in claim 1, characterized in that, In the membrane dispersion microreactor, the stainless steel microfiltration membrane has a pore size of 0.5-5μm and a diameter of 6.5-100mm; the residence tube is made of polytetrafluoroethylene, with an inner diameter of 1.5-2.5mm and a length of 0.5-100m.

4. The continuous preparation method of the supported catalyst as described in claim 1, characterized in that, In step 1), for every 150 mL of deionized water, solution A is supplemented with 0.008 mol of Cu(NO3)2·3H2O, 0.002 mol of Ce(NO3)3·6H2O, 0.027 mol of Mg(NO3)2·6H2O, and 0.013 mol of Al(NO3)3·9H2O; for every 150 mL of deionized water, solution B is supplemented with 0.075 mol of NaOH and 0.045 mol of Na2CO3. In step 2), the flow rate is 5 mL / min.

5. The continuous preparation method of the supported catalyst as described in claim 1, characterized in that, The catalyst has a specific surface area of ​​288.42 m². 2 / g, average pore size 21.78nm.

6. The continuous preparation method of the supported catalyst as described in claim 1, characterized in that, The supported catalyst comprises an active component and a support, wherein the support is magnesium oxide and aluminum oxide, the active component is main metal M1 or main metal M1 and metal M2; the molar ratio of the active component to the support is 1:4-20; the molar ratio of main metal M1 to auxiliary metal M2 is 1:0.1-0.

7. The main metal M1 is Cu; the auxiliary metal M2 is Ce.

7. The application of the catalyst prepared by the method described in claim 1 in the catalytic hydrogenation cracking of furfural, characterized in that, Includes the following steps: Furfural, isopropanol, and a supported catalyst were added to a batch high-pressure reactor. The air in the reactor was then replaced with N2, followed by H2. The reactor was then reacted at 3-6 MPa H2 pressure and 140-170 °C for 5.5-7 h to produce 1,2-pentanediol through catalytic hydrogenation cracking. The mass ratio of furfural to catalyst is 100:3:1; the molar ratio of furfural to isopropanol is 1:0:50.

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