Preparation method and application of composite catalyst for hydrogenation of furfuryl alcohol to synthesize 1,2-pentanediol

Abstract

The present invention belongs to the technical field of organic synthesis catalysts, and particularly relates to a preparation method and application of a composite catalyst for the hydrogenation of furfuryl alcohol to synthesize 1,2-pentanediol. The preparation method is to prepare an aqueous solution by mixing cerium nitrate, lanthanum nitrate, urea, a surfactant and water, and impregnate spherical γ-Al2O3 with the solution. Then, it is subjected to hydrothermal reaction, drying and calcination in sequence to obtain CeO2-La2O3 / Al2O3. An acidic solution is prepared by mixing palladium chloride, ruthenium chloride, hydrochloric acid and water, and CeO2-La2O3 / Al2O3 is impregnated with the solution. Then, it is subjected to drying, calcination and hydrogen reduction in sequence to prepare the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3. This composite catalyst can be applied to the hydrogenation of furfuryl alcohol to produce 1,2-pentanediol. By preparing the composite catalyst, the present invention solves the deficiencies of existing catalysts in terms of selectivity, stability and cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis catalysts, and particularly relates to a preparation method and application of a composite catalyst for the hydrogenation of furfuryl alcohol to synthesize 1,2-pentanediol. Background Art

[0002] 1,2-Pentanediol is a straight-chain diol and an important intermediate for synthesizing the fungicide propiconazole. It can be used as an excellent humectant and has an antiseptic effect, and can be formulated into products without preservatives. 1,2-Pentanediol can also be applied to various skin care products such as skin care creams, eye creams, skin care lotions, baby care products, and sunscreen products. At present, the main methods for synthesizing 1,2-pentanediol are the n-valeric acid method, the n-pentanol method, and the epoxidation hydrolysis method.

[0003] When ethylene is prepared by petroleum cracking, a certain amount of by-product C5 fraction is generated. The C5 fraction contains 1-pentene, which is one of the important raw materials for synthesizing 1,2-pentanediol. However, in the C5 fraction, the content of 1-pentene is less compared with cyclopentadiene, isoprene, and piperylene. Therefore, the C5 fraction is more commonly used as a fuel or for producing petroleum resins and rubbers. Separating and purifying 1-pentene will increase the cost. In addition, the complex synthesis process, many by-products, and high pollution also restrict the application of the C5 fraction in the field of synthesizing 1,2-pentanediol. Therefore, production personnel hope to find a substitute for the C5 fraction, which should have a wide source and lower cost, and should have the advantages of mild reaction conditions, fewer by-products, and more environmental protection when used to synthesize 1,2-pentanediol.

[0004] Under the action of a catalyst, furfuryl alcohol can be selectively hydrogenated to obtain 1,2-pentanediol. Different from the C5 fraction, furfuryl alcohol is mainly prepared by hydrolyzing and fermenting biomass waste to obtain furfural, and then further hydrogenating furfural. Biomass waste such as corncobs, sugarcane bagasse, or straw has the advantages of wide source, low cost, and more environmental protection. Studying the hydrogenation of furfuryl alcohol from biomass waste to prepare high-value chemicals, especially 1,2-pentanediol, is of great significance to the industrial development of biomass furan compounds. Compared with other raw materials for producing 1,2-pentanediol, furfuryl alcohol has a significant price advantage. In recent years, the research on the hydrogenation of furfuryl alcohol to prepare 1,2-pentanediol has become a hot topic, and the key to this process route is to develop a suitable and efficient catalyst.

[0005] However, the existing Cu-Zn, Cu-Cr, Raney Cu or Raney Ni catalysts used for the hydrogenation of furfuryl alcohol to prepare 1,2-pentanediol have many deficiencies. For example, the Cu-Zn catalyst has poor selectivity, and a large amount of 2-methylfuran, as well as 1,5-pentanediol and tetrahydrofurfuryl alcohol by-products will be produced during the hydrogenation of furfuryl alcohol; Cu-Cr has a large environmental toxicity; while the preparation cost of Raney Cu or Raney Ni is relatively high, the stability is insufficient, and it is more likely to be deactivated due to the deposition of carbon sulfides in biomass waste. In addition, the existing hydrogenation of furfuryl alcohol to prepare 1,2-pentanediol needs to react under high temperature and high pressure, which will also lead to an increase in reaction by-products, a low yield of 1,2-pentanediol and an increase in cost. At the same time, furfuryl alcohol contains unsaturated double bonds, which are easily polymerized to form oligomers at high temperature, covering the active sites of the catalyst and reducing the activity of the catalyst.

[0006] Chinese Patent CN104016831A discloses a method for the hydrocracking of furfuryl alcohol to prepare 1,2-pentanediol. The catalyst used in this method catalyzes the hydrocracking of furfuryl alcohol, and the catalyst is an Adams-type Pt(IV) oxide catalyst, a ruthenium supported on alumina (Al2O3) catalyst or a ruthenium supported on activated carbon catalyst.

[0007] This patent has the following disadvantages: Since the combustion method is generally used to remove carbon deposits during catalyst regeneration, activated carbon, as a support carrier, has poor strength and thermal stability, which will affect the service life during catalyst regeneration; in addition, before single alumina is modified, etc., heat accumulation is also likely to occur at high temperature, causing local sintering, making the metal active components agglomerate and affecting the dispersion. Summary of the Invention

[0008] The purpose of the present invention is to provide a preparation method of a composite catalyst for the hydrogenation of furfuryl alcohol to synthesize 1,2-pentanediol to solve the deficiencies of the existing catalysts in terms of selectivity, stability and cost; the present invention also provides the application of this composite catalyst.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is:

[0010] The preparation method of the composite catalyst for the hydrogenation of furfuryl alcohol to synthesize 1,2-pentanediol described in the present invention, the composite catalyst is Pd-Ru-CeO2-La2O3 / Al2O3, and its preparation method includes the following steps:

[0011] (1) After drying the spherical γ-Al2O3, the water absorption rate α is measured; cerium nitrate, lanthanum nitrate, urea, surfactant and water are ultrasonically dispersed and formulated into an aqueous solution, and the aqueous solution is impregnated with the spherical γ-Al2O3 in an equal volume, and then subjected to hydrothermal reaction, drying and calcination to obtain CeO2-La2O3 / Al2O3;

[0012] (2) Measure the water absorption rate β of CeO2-La2O3 / Al2O3. Prepare an acidic solution by ultrasonic dispersion of palladium chloride, ruthenium chloride, hydrochloric acid and water. Impregnate CeO2-La2O3 / Al2O3 with the acidic solution in equal volume, and then successively dry, calcine and reduce with hydrogen to obtain Pd-Ru-CeO2-La2O3 / Al2O3.

[0013] Among them:

[0014] In the step (1), the diameter of the spherical γ-Al2O3 is 1.5 - 3.5 mm; the drying temperature is 200 - 300 °C, and the drying time is 1 - 2 h; the mass ratio of the aqueous solution to the dried spherical γ-Al2O3 is 1.05α:1.

[0015] In the step (1), the molar ratio of cerium nitrate, lanthanum nitrate and urea is 1:(0.05 - 0.1):(3 - 10), the dosage of the surfactant is 0.01 - 0.1% of the total weight of cerium nitrate and urea, and the mass ratio of cerium nitrate to spherical γ-Al2O3 is (5 - 30):100; the surfactant is one of hydroxymethyl cellulose, polyethylene glycol 400 or polyethylene glycol 600; the ultrasonic dispersion time is 10 - 30 min.

[0016] In the step (1), the equal-volume impregnation time is 20 - 30 h; the hydrothermal reaction temperature is 120 - 180 °C, and the hydrothermal reaction time is 24 - 48 h; the drying temperature is 80 - 120 °C, and the drying time is 5 - 10 h; the calcination temperature is 350 - 600 °C, and the calcination time is 1 - 2 h.

[0017] In the step (2), the mass ratio of palladium element to ruthenium element in the acidic solution is 1:(0.25 - 2), and the mass ratio of palladium element in the acidic solution to spherical γ-Al2O3 is (0.1 - 0.2):100; the pH value of the acidic solution is 2 - 4, and the ultrasonic dispersion time is 10 - 30 min; the mass ratio of the acidic solution to CeO2-La2O3 / Al2O3 is 1.05β:1.

[0018] In the step (2), the equal-volume impregnation time is 20 - 30 h; the drying temperature is 80 - 100 °C, and the drying time is 3 - 5 h; the calcination temperature is 400 - 550 °C, and the calcination time is 2 - 3 h, and the hydrogen reduction temperature is 100 - 300 °C, and the hydrogen reduction time is 1 - 2 h.

[0019] Application of the composite catalyst of the present invention: Under the catalysis of Pd-Ru-CeO2-La2O3 / Al2O3, furfuryl alcohol and hydrogen are introduced for hydrogenation reaction to obtain 1,2-pentanediol.

[0020] Among them:

[0021] The molar ratio of furfuryl alcohol to hydrogen is 1:(10 - 100), and the flow rate of furfuryl alcohol is 0.51 - 3.08 g / min.

[0022] The Pd-Ru-CeO2-La2O3 / Al2O3 is packed in a fixed bed. The pressure of the fixed bed is 0.8 - 1.5 MPa, and the temperature of the fixed bed is controlled at 50 - 100 °C.

[0023] Before the hydrogenation reaction, hydrogen is introduced to activate the bed layer: the activation temperature is 120 - 130 °C, the activation pressure is 0.4 - 0.5 MPa, and the activation time is 2.5 - 3.5 h.

[0024] The volume space velocity of the hydrogenation reaction is 0.2 - 1.2 h -1 。

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) In Pd-Ru-CeO2-La2O3 / Al2O3, the coordinated action between CeO2, La2O3, Pd and Ru reduces the probability of side reactions and improves the yield of the target product 1,2-pentanediol:

[0027] CeO2 contains reversible Ce 3+ and Ce 4+ redox pairs. In this oxidation-reduction atmosphere, CeO2 reversibly releases oxygen atoms to form a certain number of oxygen vacancies on the surface. On the one hand, it plays a role in maintaining the appropriate ratio of Pd / PdO. Pd can form a synergistic catalytic effect in the dissociation of H2 and the formation of PdO in the process of forming hydroxyl groups, minimizing the existence time of unstable intermediate states, thereby effectively reducing the generation of side reactions; on the other hand, these oxygen vacancies tend to accept oxygen atoms, which can reduce the adsorption activation energy of the -O- bond in furfuryl alcohol, promote the adsorption of furfuryl alcohol on the surface of CeO2, and reduce the probability of side reactions.

[0028] The appropriate addition of La2O3 can adjust the acidity and basicity of the catalyst, introduce an appropriate proportion of basic sites on the surface of the catalyst. La is doped into the CeO2 lattice to induce the formation of more oxygen vacancies. At the same time, the basic sites of La2O3 and the acidic sites of CeO2 form an acid-base bifunctional surface, optimizing the adsorption configuration of reactants and preventing their premature desorption (for example, due to premature desorption, 2-methylfuran is generated because the hydroxyl group is removed before complete hydrogenation, leaving an unsaturated furan ring).

[0029] In the process of catalytic hydrogenation of furfuryl alcohol, unsaturated hydrocarbons and mercaptan impurities in furfuryl alcohol are more likely to deposit carbon sulfide on the catalyst surface, resulting in catalyst deactivation. Generally, the combustion method is used to remove deposits such as coke. However, γ-Al2O3 supported catalysts are prone to sintering at high temperatures (above 600 °C). Sintering will cause Pd and Ru to agglomerate, affecting the dispersion and covering the active sites. By adding La2O3, during the catalyst regeneration, La2O3 will rearrange with part of γ-Al2O3 to form a more heat-resistant LaAlO3-like structure, inhibiting the sintering phenomenon during the regeneration of γ-Al2O3 catalysts, facilitating the high-temperature regeneration of the catalyst, and being beneficial to extending the service life of the catalyst. In addition, La2O3 will form a composite crystal phase with Pd and Ru during calcination and hydrogen reduction, promoting the dispersion of the two active sites of Pd and Ru and ensuring the catalytic activity of Pd and Ru.

[0030] In the present invention, Pd and Ru are the main active components: Pd and Ru form a bifunctional effect, that is, they catalyze different reaction steps respectively: Pd is used as an efficient hydrogenation catalyst, which can adsorb and activate H2 molecules, and PdO can promote the activated hydrogen to form a hydroxyl group (-OH) with an oxygen atom at the 2' site; the addition of Ru can improve the selectivity to 1,2-pentanediol; the two cooperate to catalyze the preparation of 1,2-pentanediol from furfuryl alcohol.

[0031] There is also a ligand effect between Pd and Ru. In Pd-Ru type catalysts, the ligand effect is manifested as Ru changing the electronic structure and d-orbital characteristics of Pd, thereby affecting the adsorption and activation ability of Pd for hydrogen molecules. This effect can regulate the catalytic activity of Pd and enhance the selectivity of Pd; through experimental verification and spectral analysis, the introduction of Ru by appropriate dosage and processing methods plays a role in promoting the formation of 1,2-pentanediol.

[0032] (2) Since the main raw material for preparing furfuryl alcohol is biomass waste, furfuryl alcohol contains a small amount of unsaturated hydrocarbons, mercaptans and other substances. These substances are prone to form carbon sulfide deposits on the catalyst surface during catalytic hydrogenation over time, resulting in catalyst deactivation. The coordinated action between CeO2 and La2O3 in Pd-Ru-CeO2-La2O3 / Al2O3 and Pd and Ru reduces the phenomena of coke and sulfide deposition, ensuring the activity of the catalyst for long-term use:

[0033] Part of La2O3 enters the lattice of CeO2. On the one hand, it can inhibit the growth of the CeO2 lattice and reduce the deposition sites of carbon sulfides. On the other hand, it also increases the specific surface area of the catalyst, ensures the dispersion of Pd and Ru, increases the number of active sites. A larger specific surface area means that more sites participate in the reaction, reducing the possibility of carbon deposition on a single site, thereby maintaining the long-term activity of the catalyst. The oxygen vacancies in CeO2 also contribute to improving the redox ability of the catalyst, thereby reducing carbon deposition and sulfide deposition and maintaining the long-term activity of the catalyst. Verified by experiments, after 6 months of operation of the composite catalyst obtained in the present invention, the yield of 1,2-pentanediol is still greater than 80%, indicating that its catalytic activity can be maintained stably for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a scanning electron microscope image of the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3 in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will be specifically described and illustrated below in conjunction with the examples.

[0036] Example 1

[0037] Measure the water absorption rate α of spherical γ-Al2O3:

[0038] Take 130 g of spherical γ-Al2O3 with a diameter of 1.5 - 3.5 mm. After ultrasonic cleaning, place it in a muffle furnace, heat it to 300 °C, dry it for 60 min and then take it out and cool it to room temperature. Accurately weigh 2.000 g of the dried spherical γ-Al2O3 and place it in a flask. After evacuating, introduce distilled water until the spherical γ-Al2O3 is submerged. After standing for 15 min, filter it. Place the wetted spherical γ-Al2O3 in a constant temperature operating box with a humidity of 90% and stand for 40 min. Weigh the mass and calculate the water absorption rate α to be 65.2%.

[0039] (1) Prepare CeO2-La2O3 / Al2O3: Weigh 20 g of cerium nitrate, 1.99 g of lanthanum nitrate, 18.41 g of urea and 0.019 g of hydroxymethyl cellulose respectively. Mix cerium nitrate, lanthanum nitrate, urea and hydroxymethyl cellulose with distilled water, and ultrasonically disperse for 25 min to prepare a mixed solution A with a mass of 105α g. Another 100 g of the dried spherical γ-Al2O3 is placed in a flask. According to the mass ratio of the mixed solution A to the spherical γ-Al2O3 of 1.05α:1, impregnate the spherical γ-Al2O3 with equal volume, stand for 20 h, and then put them into an autoclave together for hydrothermal reaction at 150 °C for 36 h. Place it in a microwave oven and dry it at 100 °C for 8 h, and calcine it in a muffle furnace at 350 °C for 120 min to obtain CeO2-La2O3 / Al2O3.

[0040] (2) Preparation of the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3: Accurately weigh 2.000 g of the calcined CeO2-La2O3 / Al2O3. According to the method for measuring the water absorption rate α in Example 1, the water absorption rate β of CeO2-La2O3 / Al2O3 is measured to be 63.6%. Weigh 0.265 g of palladium chloride, 0.082 g of ruthenium chloride, hydrochloric acid and distilled water, mix them evenly, and disperse them ultrasonically for 10 min to prepare a mixed solution B with a mass of 105β g. The pH of the mixed solution B is 4. Another 100 g of the calcined CeO2-La2O3 / Al2O3 is weighed and put into a flask. According to the mass ratio of the mixed solution B to CeO2-La2O3 / Al2O3 of 1.05β:1, impregnate CeO2-La2O3 / Al2O3 with equal volume, let it stand for 20 h, then put them into a microwave oven together and dry at 95 °C for 4 h. Then continue to put them into a muffle furnace and calcine at 480 °C for 160 min. Pass hydrogen into a tubular furnace at 250 °C and react for 90 min to prepare the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3.

[0041] (3) Preparation of 1,2-pentanediol: Load Pd-Ru-CeO2-La2O3 / Al2O3 into a fixed-bed reactor with a diameter of DN25 to form a bed layer with an effective loading height of 0.3 m. The upper and lower parts of the bed layer are porcelain ring layers, and the height of each porcelain ring layer is 10 cm. Replace the gas in the bed layer with nitrogen for 30 min, and then replace it with hydrogen for 30 min. Use heat transfer oil to raise the temperature of the bed layer to 130 °C and the pressure to 0.5 MPa, and pass hydrogen for activation. The activation time is 3 h.

[0042] Control the furfuryl alcohol (the density of furfuryl alcohol is 1.135 g / cm 3 ) to continuously enter the fixed-bed reactor at a speed of 0.51 g / min, control the hydrogen flow rate to 0.104 g / min to enter the fixed bed. The volume space velocity of the hydrogenation reaction is 0.2 h -1 , the molar ratio of furfuryl alcohol to hydrogen is 1:10. Control the temperature of the bed layer to 50 °C and the pressure of the bed layer to 1.5 MPa through heat transfer oil. After reacting for 5 h, take a sample for analysis: the content of 1,2-pentanediol is 73.28%, the content of 1,5-pentanediol is 11.65%, the content of tetrahydrofurfuryl alcohol is 14.16%, and the content of furfuryl alcohol is 0.89%. The fixed bed operates continuously for one day, and a total of 734.4 g of furfuryl alcohol is consumed. The reaction liquid is obtained by hydrogenation of furfuryl alcohol, and the reaction liquid is purified by distillation to obtain 1,2-pentanediol with a purity of 99.61%. The conversion rate of furfuryl alcohol is 99.03%, the selectivity of 1,2-pentanediol is 82.74%, and the yield is 81.94%. When the catalyst is used for 6 months, the activity of the catalyst does not decrease significantly.

[0043] Example 2

[0044] Measure the water absorption rate α of spherical γ-Al2O3:

[0045] Take 130 g of spherical γ-Al2O3 with a diameter of 1.5 - 3.5 mm. After ultrasonic cleaning, place it in a muffle furnace, heat it to 220 °C, dry it for 120 min, then take it out and cool it to room temperature. Accurately weigh 2.000 g of the dried spherical γ-Al2O3 and place it in a flask. After evacuating, introduce distilled water until the spherical γ-Al2O3 is submerged. Let it stand for 15 min and then filter. Place the wetted spherical γ-Al2O3 in a constant-temperature operating box with a humidity of 90% and let it stand for 40 min. Weigh the mass and calculate the water absorption rate α to be 66.7%.

[0046] (1) Prepare CeO2-La2O3 / Al2O3: Weigh 30 g of cerium nitrate, 1.495 g of lanthanum nitrate, 16.58 g of urea, and 0.0466 g of polyethylene glycol 400 respectively. Mix cerium nitrate, lanthanum nitrate, urea, and polyethylene glycol 400 with distilled water and disperse them ultrasonically for 30 min to prepare a mixed solution A with a mass of 105α g. Weigh another 100 g of the dried spherical γ-Al2O3 and put it into a flask. According to the mass ratio of mixed solution A to spherical γ-Al2O3 of 1.05α:1, impregnate the spherical γ-Al2O3 with equal volume, let it stand for 25 h, then put them together into an autoclave and carry out hydrothermal reaction at 120 °C for 48 h. Place it in a microwave oven and dry it at 120 °C for 5 h, and then calcine it in a muffle furnace at 400 °C for 95 min to obtain CeO2-La2O3 / Al2O3.

[0047] (2) Prepare the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3: Accurately weigh 2.000 g of the calcined CeO2-La2O3 / Al2O3. According to the method of measuring the water absorption rate α in Example 2, measure the water absorption rate β of CeO2-La2O3 / Al2O3 to be 64.3%. Weigh 0.165 g of palladium chloride, 0.41 g of ruthenium chloride, hydrochloric acid, and distilled water and mix them evenly. Disperse them ultrasonically for 30 min to prepare a mixed solution B with a mass of 105β g. The pH of the mixed solution B is 3. Weigh another 100 g of the calcined CeO2-La2O3 / Al2O3 and put it into a flask. According to the mass ratio of mixed solution B to CeO2-La2O3 / Al2O3 of 1.05β:1, impregnate CeO2-La2O3 / Al2O3 with equal volume, let it stand for 30 h, then put them together into a microwave oven and dry it at 100 °C for 3 h. Then continue to put it into a muffle furnace and calcine it at 550 °C for 120 min, and introduce hydrogen in a tubular furnace at 300 °C and react for 60 min to prepare the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3.

[0048] (3) Preparation of 1,2-pentanediol: Load Pd-Ru-CeO2-La2O3 / Al2O3 into a fixed-bed reactor with a diameter of DN25 to form a bed layer with an effective loading height of 0.3 m. The upper and lower parts of the bed layer are porcelain ring layers, and the height of each porcelain ring layer is 10 cm. Replace the gas in the bed layer with nitrogen for 30 min, and then replace it with hydrogen for 30 min. Raise the temperature of the bed layer to 125 °C and the pressure to 0.4 MPa with heat transfer oil, and pass hydrogen for activation for 3.5 h.

[0049] Control the furfuryl alcohol (the density of furfuryl alcohol is 1.135 g / cm 3 ) to continuously enter the fixed-bed reactor at a speed of 1.54 g / min, control the hydrogen flow rate to 0.63 g / min to enter the fixed bed, and the volume space velocity of the hydrogenation reaction is 0.6 h -1 . The molar ratio of furfuryl alcohol to hydrogen is 1:20. Control the temperature of the bed layer to 80 °C and the pressure of the bed layer to 1.0 MPa with heat transfer oil. After reacting for 5 h, take a sample for analysis: the content of 1,2-pentanediol is 75.68%, the content of 1,5-pentanediol is 18.86%, the content of tetrahydrofurfuryl alcohol is 4.87%, and the content of furfuryl alcohol is 0.22%. The fixed bed operates continuously for one day, consuming a total of 2217.6 g of furfuryl alcohol. The reaction solution is obtained by hydrogenation of furfuryl alcohol, and the reaction solution is purified by distillation to obtain 1,2-pentanediol with a purity of 99.66%. The conversion rate of furfuryl alcohol is 99.78%, the selectivity of 1,2-pentanediol is 82.05%, and the yield is 81.87%. When the catalyst is used for 6 months, the activity of the catalyst does not decrease significantly.

[0050] Example 3

[0051] Measure the water absorption rate α of spherical γ-Al2O3:

[0052] Take 130 g of spherical γ-Al2O3 with a diameter of 1.5 - 3.5 mm. After ultrasonic cleaning, place it in a muffle furnace, heat it to 200 °C, take it out after drying for 100 min, and cool it to room temperature. Accurately weigh 2.000 g of the dried spherical γ-Al2O3 and place it in a flask. After evacuating, introduce distilled water until the spherical γ-Al2O3 is submerged. Filter it after standing for 15 min. Place the wet spherical γ-Al2O3 in a constant-temperature operating box with a humidity of 90% and stand for 40 min. Weigh the mass and calculate the water absorption rate α to be 64.5%.

[0053] (1) Preparation of CeO2-La2O3 / Al2O3: Weigh 5 g of cerium nitrate, 0.39 g of lanthanum nitrate, 9.19 g of urea and 0.00142 g of polyethylene glycol 600 respectively. Mix cerium nitrate, lanthanum nitrate, urea and polyethylene glycol 600 with distilled water, and disperse them by ultrasonic for 10 min to prepare a mixed solution A with a mass of 105α g. Weigh another 100 g of dried spherical γ-Al2O3 and put it into a flask. Impregnate the spherical γ-Al2O3 with the mixed solution A in an equal volume according to the mass ratio of the mixed solution A to the spherical γ-Al2O3 of 1.05α:1, and let it stand for 30 h. Then put them into an autoclave together and carry out hydrothermal reaction at 180 °C for 24 h. Put it into a microwave oven and dry it at 80 °C for 10 h, and then calcine it in a muffle furnace at 600 °C for 60 min to obtain CeO2-La2O3 / Al2O3.

[0054] (2) Preparation of the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3: Accurately weigh 2.000 g of the calcined CeO2-La2O3 / Al2O3. According to the method for measuring the water absorption rate α in Example 1, the water absorption rate β of CeO2-La2O3 / Al2O3 is measured to be 63.1%. Weigh 0.33 g of palladium chloride, 0.41 g of ruthenium chloride, hydrochloric acid and distilled water and mix them evenly, and disperse them by ultrasonic for 20 min to prepare a mixed solution B with a mass of 105β g. The pH of the mixed solution B is 2. Weigh another 100 g of the calcined CeO2-La2O3 / Al2O3 and put it into a flask. Impregnate the CeO2-La2O3 / Al2O3 with the mixed solution B in an equal volume according to the mass ratio of the mixed solution B to the CeO2-La2O3 / Al2O3 of 1.05β:1, and let it stand for 25 h. Then put them into a microwave oven together and dry them at 80 °C for 5 h. Then continue to put them into a muffle furnace and calcine them at 400 °C for 180 min, and then introduce hydrogen at 100 °C in a tubular furnace and react for 120 min to prepare the composite catalyst Pd-Ru-CeO2-La2O3 / Al2O3.

[0055] (3) Preparation of 1,2-pentanediol: Load Pd-Ru-CeO2-La2O3 / Al2O3 into a fixed-bed reactor with a diameter of DN25 to form a bed layer with an effective loading height of 0.3 m. The upper and lower parts of the bed layer are porcelain ring layers, and the height of each porcelain ring layer is 10 cm. Replace the gas in the bed layer with nitrogen for 30 min, and then replace it with hydrogen for 30 min. Use heat transfer oil to raise the temperature of the bed layer to 120 °C and the pressure to 0.5 MPa, and introduce hydrogen for activation. The activation time is 2.5 h.

[0056] Control the continuous entry of furfuryl alcohol (the density of furfuryl alcohol is 1.135 g / cm 3 ) into the fixed-bed reactor at a speed of 3.08 g / min, and control the hydrogen flow rate of 1.89 g / min to enter the fixed bed. The volume space velocity of the hydrogenation reaction is 1.2 h-1 The molar ratio of furfuryl alcohol to hydrogen is 1:30. The temperature of the bed layer is controlled at 100 °C by means of heat transfer oil, the bed layer pressure is 0.8 MPa, and after reacting for 5 h, a sample is taken for analysis: the content of 1,2-pentanediol is 71.26%, the content of 1,5-pentanediol is 23.58%, the content of tetrahydrofurfuryl alcohol is 4.25%, and the content of furfuryl alcohol is 0.18%. The fixed bed operates continuously for one day, consuming a total of 4435.2 g of furfuryl alcohol. The reaction solution is obtained by hydrogenation of furfuryl alcohol, and the reaction solution is purified by distillation to obtain 1,2-pentanediol with a purity of 99.72%. The conversion rate of furfuryl alcohol is 99.81%, the selectivity of 1,2-pentanediol is 82.33%, and the yield is 82.17%. When the catalyst is used for 6 months, the activity of the catalyst does not decrease significantly.

[0057] Comparative Example 1

[0058] CeO2-La2O3 / Al2O3 was replaced by activated carbon, and the remaining steps were the same as in Example 1 to prepare a Pd-Ru / AC catalyst.

[0059] The Pd-Ru / AC catalyst was used to prepare 1,2-pentanediol, and the operating steps were the same as in Example 1. The fixed bed operates continuously for one day, consuming a total of 734.4 g of furfuryl alcohol. The reaction solution is purified by distillation to obtain 1,2-pentanediol with a purity of 99.56%. The conversion rate of furfuryl alcohol is 76.82%, the selectivity of 1,2-pentanediol is 50.69%, and the yield is 38.94%. When the catalyst is used for 1 month, the conversion rate of the raw material furfuryl alcohol drops to 61.78%, and the activity of the catalyst decreases significantly.

[0060] Comparative Example 2

[0061] An aqueous solution was not prepared. Only the spherical γ-Al2O3 was dried, and then an acidic solution was prepared and impregnated with the dried spherical γ-Al2O3 in an equal volume. The remaining steps were the same as in Example 1 to prepare a Pd-Ru / Al2O3 catalyst.

[0062] The Pd-Ru / Al2O3 catalyst was used to prepare 1,2-pentanediol, and the operating steps were the same as in Example 1. The fixed bed operates continuously for one day, consuming a total of 734.4 g of furfuryl alcohol. The reaction solution is purified by distillation to obtain 1,2-pentanediol with a purity of 99.65%. The conversion rate of furfuryl alcohol is 95.18%, the selectivity of 1,2-pentanediol is 50.55%, and the yield is 48.11%. When operating for one month, the yield decreases, and the yield drops to 44.37%.

[0063] Comparative Example 3

[0064] Palladium chloride and ruthenium chloride were replaced by copper nitrite, and the remaining steps were the same as in Example 1. A Cu-CeO2-La2O3 / Al2O3 catalyst was prepared.

[0065] The Cu-CeO2-La2O3 / Al2O3 catalyst was used for the preparation of 1,2-pentanediol, and the operating steps were the same as those in Example 1. It was continuously operated in a fixed bed for one day, and a total of 734.4 g of furfuryl alcohol was consumed. The reaction solution was purified by distillation to obtain 1,2-pentanediol with a purity of 99.63%. The conversion rate of furfuryl alcohol was 90.78%, the selectivity of 1,2-pentanediol was 56.77%, and the yield was 51.54%. When it was operated for one month, the yield decreased, and the conversion rate relative to furfuryl alcohol decreased to 80.27%, and the catalyst activity decreased significantly.

[0066] Comparative Example 4

[0067] Ruthenium chloride was replaced with palladium chloride, and the other steps were the same as those in Example 1. The Pd-CeO2-La2O3 / Al2O3 catalyst was prepared.

[0068] The Pd-CeO2-La2O3 / Al2O3 catalyst was used for the preparation of 1,2-pentanediol, and the operating steps were the same as those in Example 1. It was continuously operated in a fixed bed for one day, and a total of 734.4 g of furfuryl alcohol was consumed. The reaction solution was purified by distillation to obtain 1,2-pentanediol with a purity of 99.58%. The conversion rate of furfuryl alcohol was 88.78%, the selectivity of 1,2-pentanediol was 51.80%, and the yield was 45.99%. When it was operated for one month, the conversion rate relative to furfuryl alcohol dropped to 65.72%, and the catalyst activity decreased significantly.

[0069] Comparative Example 5

[0070] Palladium chloride was replaced with ruthenium chloride, and the other steps were the same as those in Example 1. The Ru-CeO2-La2O3 / Al2O3 catalyst was prepared.

[0071] The Ru-CeO2-La2O3 / Al2O3 catalyst was used for the preparation of 1,2-pentanediol, and the operating steps were the same as those in Example 1. It was continuously operated in a fixed bed for one day, and a total of 734.4 g of furfuryl alcohol was consumed. The reaction solution was purified by distillation to obtain 1,2-pentanediol with a purity of 99.62%. The conversion rate of furfuryl alcohol was 98.78%, the selectivity of 1,2-pentanediol was 54.42%, and the yield was 53.76%. When it was operated for one month, the yield was 37.65%, and the yield decreased.

[0072] After 6 months of operation, when the catalysts obtained in Examples 1-3 were used to synthesize 1,2-pentanediol, the yield data of 1,2-pentanediol were as follows:

[0073]

[0074] Evaluation of implementation effect: From the yield data of Examples 1-3 and Comparative Examples 1-5, it can be seen that for the catalysts in Examples 1-3, after 6 months of use, the catalytic effect of the catalysts still meets the use standards, indicating that the catalyst has a good service life and can be regenerated and used multiple times. However, for the catalysts in Comparative Examples 1-5, the catalyst activity decreased rapidly after 1 month of use, and no subsequent evaluation experiments were carried out.

[0075] From Comparative Examples 1-5, it can be seen that Comparative Examples 1 and 2 cannot exert the synergistic effect of CeO2-La2O3; Comparative Examples 3, 4, and 5 cannot exert the synergistic effect of Pd-Ru. From this, it can be known that the use effect of the present invention cannot be achieved without CeO2-La2O3 or Pd-Ru.

Claims

1. A method for preparing a composite catalyst for hydrogenating furfuryl alcohol to synthesize 1,2-pentanediol, characterized in that: The composite catalyst is Pd-Ru-CeO2-La2O3 / Al2O3, and its preparation method comprises the following steps: (1) After drying the spherical γ-Al2O3, the water absorption rate α is measured; cerium nitrate, lanthanum nitrate, urea, surfactant and water are prepared into an aqueous solution by ultrasonic dispersion, the spherical γ-Al2O3 is impregnated with an equal volume of the aqueous solution, and then subjected to hydrothermal reaction, drying and roasting in sequence to obtain CeO2-La2O3 / Al2O3; wherein the molar ratio of cerium nitrate, lanthanum nitrate and urea is 1:(0.05-0.1):(3-10); the mass ratio of cerium nitrate to spherical γ-Al2O3 is (5-30):100; (2) The water absorption rate β of CeO2-La2O3 / Al2O3 is measured, palladium chloride, ruthenium chloride, hydrochloric acid and water are prepared into an acidic solution by ultrasonic dispersion, and CeO2-La2O3 / Al2O3 is impregnated with an equal volume of the acidic solution, and the pH value of the acidic solution is 2-4; Pd-Ru-CeO2-La2O3 / Al2O3 is prepared by drying, roasting and hydrogen reduction in sequence; wherein the mass ratio of palladium element to ruthenium element in the acidic solution is 1:(0.25-2); and the mass ratio of palladium element to spherical γ-Al2O3 in the acidic solution is (0.1-0.2):

100.

2. The method for preparing a composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to claim 1, characterized in that: In step (1), the diameter of the spherical γ-Al2O3 is 1.5-3.5 mm; the drying temperature is 200-300°C, and the drying time is 1-2 h; the mass ratio of the aqueous solution to the dried spherical γ-Al2O3 is 1.05α:

1.

3. The method for preparing a composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to claim 1, characterized in that: In step (1), the amount of surfactant used is 0.01-0.1% of the total weight of cerium nitrate and urea, and the surfactant is one of hydroxymethyl cellulose, polyethylene glycol 400 or polyethylene glycol 600; and the ultrasonic dispersion time is 10-30 minutes.

4. The method for preparing a composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to claim 1, characterized in that: In step (1), the equal volume impregnation time is 20-30 hours; the hydrothermal reaction temperature is 120-180°C, and the hydrothermal reaction time is 24-48 hours; the drying temperature is 80-120°C, and the drying time is 5-10 hours; the roasting temperature is 350-600°C, and the roasting time is 1-2 hours.

5. The method for preparing the composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to claim 1, characterized in that: In step (2), the ultrasonic dispersion time is 10-30 min; the mass ratio of the acidic solution to CeO2-La2O3 / Al2O3 is 1.05β:

1.

6. The method for preparing the composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to claim 1, characterized in that: In step (2), the equal volume impregnation time is 20-30 hours; the drying temperature is 80-100°C, and the drying time is 3-5 hours; the roasting temperature is 400-550°C, and the roasting time is 2-3 hours; the hydrogen reduction temperature is 100-300°C, and the hydrogen reduction time is 1-2 hours.

7. Use of a composite catalyst prepared by the method for preparing a composite catalyst for synthesizing 1,2-pentanediol by hydrogenation of furfuryl alcohol according to any one of claims 1 to 6, characterized in that: Under the catalysis of Pd-Ru-CeO2-La2O3 / Al2O3, furfuryl alcohol and hydrogen are introduced for hydrogenation reaction to obtain 1,2-pentanediol.

8. The use of the composite catalyst according to claim 7, characterized in that: The molar ratio of furfuryl alcohol to hydrogen is 1:(10-30).

9. The use of the composite catalyst according to claim 7, characterized in that: Pd-Ru-CeO2-La2O3 / Al2O3 is loaded in a fixed bed with a pressure of 0.8-1.5MPa and a temperature control of 50-100℃.

10. The use of the composite catalyst according to claim 7, characterized in that: The volume space velocity of hydrogenation reaction is 0.2-1.2h -1 .

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