Synthetic method of glutaric acid

Abstract

The invention provides a synthetic method of glutaric acid, and belongs to the technical field of organic synthesis. The method provided by the invention comprises the following steps: mixing furfural, a polymerization inhibitor, a first catalyst and a first solvent, introducing H2 under a closed condition, and carrying out a hydrogenation reaction to obtain an intermediate product containing cyclopentanone; and mixing the intermediate product containing cyclopentanone with a second catalyst and a second solvent, introducing O2 under a closed condition, and carrying out an oxidation reaction to obtain glutaric acid. Glutaric acid is prepared from biomass furfural through a hydrogenation reaction and oxidation reaction two-step method, and the process is green and environmentally friendly; the polymerization inhibitor is added to react with free radicals which are generated in the furfural heating process and initiate the polymerization reaction to generate low-activity free radicals or non-free radical substances which cannot initiate the polymerization reaction, so that the polymerization reaction among furfural molecules is inhibited. Tests show that according to the synthesis method provided by the invention, the conversion rate of furfural is 84% or above, and the yield of glutaric acid is 60% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing glutaric acid. Background Art

[0002] Glutaric acid is a five-carbon dicarboxylic acid and is the raw material for synthesizing nylon-45 and nylon-55. The odd carbon structure of glutaric acid can effectively reduce the crystallinity of polymers, making them more elastic, water-soluble and easier to handle. Glutaric acid is also one of the metabolites of the human body, and glutaric acid polymers have good biocompatibility. Glutaric acid can also be widely used as a plasticizer for polyester plastics, which has more outstanding advantages than adipic acid plasticizers.

[0003] The traditional production methods of glutaric acid include separation and recovery from adipic acid byproducts, or generation through oxidation of γ-butyrolactone, dihydropyran, cyclopentene, etc. The separation and recovery from adipic acid byproducts has a complex technical route, and with the advancement of adipic acid production technology, the byproducts are becoming less and less, and the direct yield of glutaric acid is also reduced; in addition, nitric acid is generally used as an oxidant in the generation through oxidation of γ-butyrolactone, dihydropyran, cyclopentene, etc., and toxic substances such as potassium cyanide are also used in the process, which is harmful to the human body and seriously pollutes the environment. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for synthesizing glutaric acid. The synthetic method provided by the present invention has simple preparation steps and is green and environmentally friendly.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a method for synthesizing glutaric acid, comprising the following steps:

[0007] Furfural, polymerization inhibitor, first catalyst and first solvent are mixed, and H 2 , and undergoing a hydrogenation reaction to obtain an intermediate product containing cyclopentanone;

[0008] The intermediate product containing cyclopentanone is mixed with a second catalyst and a second solvent, and O is introduced into the mixture under a closed condition. 2 , carrying out an oxidation reaction to obtain the glutaric acid;

[0009] The first catalyst and the second catalyst include a carrier and an active metal;

[0010] The active metal in the first catalyst is one or more of Ni, Co, Fe, Cu, Au, Pt, Pd, and Rh;

[0011] The active metal in the second catalyst is one or more of Ni, Co, Cu, Au, Pt, Pd and Ru;

[0012] The carriers in the first catalyst and the second catalyst are independently silicon dioxide, aluminum oxide, zirconium oxide, cerium oxide or activated carbon;

[0013] The first solvent is water or acetonitrile;

[0014] The second solvent is water or acetic acid;

[0015] The temperature of the hydrogenation reaction is 170-200°C and the time is 3-5h;

[0016] The oxidation reaction temperature is 50-120°C and the time is 5-12h;

[0017] The mass of the furfural accounts for 1-5% of the total mass of the furfural and the first solvent.

[0018] Preferably, in the first catalyst and the second catalyst, the loading amount of the active metal on the carrier is independently 1 to 10% of the weight of the carrier.

[0019] Preferably, the first catalyst comprises Pt / SiO 2 、Pt / Al 2 O 3 、Pt / ZrO 2 、PtNi / SiO 2 or PtPd / SiO 2 .

[0020] Preferably, the second catalyst comprises PtAu / CeO 2 or PtRu / CeO 2 .

[0021] Preferably, the molar ratio of the active metal to furfural in the first catalyst is 1:300-2000.

[0022] Preferably, the molar ratio of the active metal in the second catalyst to the cyclopentanone in the intermediate product containing cyclopentanone is 1:300-2000.

[0023] Preferably, the polymerization inhibitor is hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol or a quinone polymerization inhibitor.

[0024] Preferably, the mass of the polymerization inhibitor accounts for 0.01-0.1% of the mass of furfural.

[0025] Preferably, the introduction of H 2 The pressure is 5~20MPa.

[0026] Preferably, the introduction of 2 The pressure is 0.5~6MPa.

[0027] The present invention provides a method for synthesizing glutaric acid, comprising the following steps: mixing furfural, an inhibitor, a first catalyst and a first solvent, introducing H 2 , performing a hydrogenation reaction to obtain an intermediate product containing cyclopentanone; mixing the intermediate product with a second catalyst and a second solvent, and introducing O under closed conditions 2 , and carry out oxidation reaction to obtain the glutaric acid; the first catalyst and the second catalyst include a carrier and an active metal; the active metal in the first catalyst and the second catalyst is independently one or more of Ni, Co, Fe, Cu, Au, Pt, Pd and Rh; the carrier in the first catalyst and the second catalyst is independently silica, alumina, zirconium oxide, cerium oxide or activated carbon; the first solvent is water or acetonitrile; the second solvent is water or acetic acid; the temperature of the hydrogenation reaction is 170-200°C, and the time is 3-5h; the temperature of the oxidation reaction is 50-120°C, and the time is 5-12h; the mass of furfural accounts for 1-5% of the total mass of furfural and the first solvent. The present invention uses biomass furfural to prepare glutaric acid, and obtains glutaric acid by a two-step method of hydrogenation reaction and oxidation reaction, and the process is green and environmentally friendly; an inhibitor is added to react with the free radicals that initiate the polymerization reaction generated during the heating of furfural to generate low-activity free radicals or non-free radical substances that cannot initiate the polymerization reaction, thereby inhibiting the polymerization reaction between furfural molecules. The synthesis method provided by the invention is green and pollution-free, has high economic benefits, is simple and convenient in process, and has high efficiency. Through testing, it can be known that the synthesis method provided by the invention has a furfural conversion rate of more than 84% and a glutaric acid yield of more than 60%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 The present invention provides a biomass glutaric acid synthesis route. DETAILED DESCRIPTION

[0030] The present invention provides a method for synthesizing glutaric acid, comprising the following steps:

[0031] Furfural, polymerization inhibitor, first catalyst and first solvent are mixed, and H 2 , and undergoing a hydrogenation reaction to obtain an intermediate product containing cyclopentanone;

[0032] The intermediate product containing cyclopentanone is mixed with a second catalyst and a second solvent, and O is introduced into the mixture under a closed condition. 2 , carrying out an oxidation reaction to obtain the glutaric acid;

[0033] The first catalyst and the second catalyst include a carrier and an active metal;

[0034] The active metal in the first catalyst is one or more of Ni, Co, Fe, Cu, Au, Pt, Pd, and Rh;

[0035] The active metal in the second catalyst is one or more of Ni, Co, Cu, Au, Pt, Pd and Ru;

[0036] The carriers in the first catalyst and the second catalyst are independently silicon dioxide, aluminum oxide, zirconium oxide, cerium oxide or activated carbon;

[0037] The first solvent is water or acetonitrile;

[0038] The second solvent is water or acetic acid;

[0039] The temperature of the hydrogenation reaction is 170-200°C and the time is 3-5h;

[0040] The oxidation reaction temperature is 50-120°C and the time is 5-12h;

[0041] The mass of the furfural accounts for 1-5% of the total mass of the furfural and the first solvent.

[0042] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0043] The chemical formula of the synthesis method of glutaric acid provided by the present invention is as follows: Figure 1 .

[0044] The method comprises mixing furfural, a polymerization inhibitor, a first catalyst and a first solvent, introducing H 2 , and undergo a hydrogenation reaction to obtain an intermediate product containing cyclopentanone.

[0045] In the present invention, the polymerization inhibitor is preferably hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol or a quinone polymerization inhibitor, and the quinone polymerization inhibitor preferably includes p-benzoquinone and / or methylhydroquinone, and the polymerization inhibitor is more preferably hydroquinone or p-hydroxyanisole, and further preferably hydroquinone. During the heating process, the polymerization inhibitor and furfural generate low-activity free radicals or non-free radical substances that cannot initiate polymerization reaction, thereby inhibiting the polymerization reaction between furfural molecules.

[0046] In the present invention, the mass of the polymerization inhibitor preferably accounts for 0.01 to 0.1% of the mass of furfural, more preferably 0.03 to 0.08%, and further preferably 0.05%.

[0047] In the present invention, the mass of furfural accounts for 1-5%, preferably 2-4%, more preferably 3% of the total mass of furfural and the first solvent. In a specific embodiment of the present invention, the mass of furfural preferably accounts for 5% of the total mass of furfural and the first solvent.

[0048] In the present invention, the first solvent is water or acetonitrile, preferably water.

[0049] In the present invention, the first catalyst comprises a carrier and an active metal, and the active metal in the first catalyst is one or more of Ni, Co, Fe, Cu, Au, Pt, Pd, and Rh, preferably one or more of Ni, Pt, and Pd, and more preferably Pt, PtNi, or PtPd. In the present invention, the carrier in the first catalyst is silica, alumina, zirconia, cerium oxide, or activated carbon, preferably silica, alumina, or zirconia.

[0050] In the present invention, the preparation of the first catalyst preferably comprises: reducing the active metal by liquid phase reduction, H 2 Reduction method or NaBH 4 The reduction method is loaded on the carrier.

[0051] The preparation methods of the above carrier and the first catalyst are well known in the art and will not be discussed in detail here.

[0052] In the present invention, the loading amount of the active metal in the first catalyst on the carrier is preferably 1-10% of the weight of the carrier, more preferably 2-8%, and further preferably 3-6%. In a specific embodiment of the present invention, the loading amount of the active metal on the carrier is 2%, 3% or 4% of the weight of the carrier.

[0053] In the present invention, the first catalyst preferably comprises Pt / SiO 2 、Pt / Al 2 O 3 、Pt / ZrO 2 、PtNi / SiO 2 or PtPd / SiO 2 , more preferably Pt / ZrO 2 or PtPd / SiO 2 , more preferably PtPd / SiO 2 In a specific embodiment of the present invention, PtPd / SiO 2 The Pt loading is 2 wt% and the Pd loading is 2 wt%.

[0054] In the present invention, the molar ratio of the active metal to furfural in the first catalyst is preferably 1:300 to 1:2000, more preferably 1:400 to 800, and further preferably 1:500 to 600.

[0055] In the present invention, the temperature of the hydrogenation reaction is preferably 170-200°C, more preferably 180-190°C, and the time is preferably 3-5h, more preferably 4h. 2 The pressure is preferably 5 to 20 MPa, more preferably 8 to 15 MPa. In the hydrogenation reaction, furfural is converted into cyclopentanone and other by-products (such as furfuryl alcohol, 2-methylfuran, 1,2-pentanediol and 1,5-pentanediol) under the action of catalyst and hydrogen.

[0056] After obtaining the intermediate product containing cyclopentanone, the present invention mixes the intermediate product containing cyclopentanone with a second catalyst and a second solvent, and introduces O under a closed condition. 2 , and undergo oxidation reaction to obtain the glutaric acid.

[0057] In the present invention, the second catalyst comprises a carrier and an active metal, and the active metal in the second catalyst is one or more of Ni, Co, Cu, Au, Pt, Pd and Ru, preferably one or more of Au, Pt and Ru, more preferably PtAu or PtRu. In the present invention, the first catalyst is silica, alumina, zirconia, cerium oxide or activated carbon, more preferably cerium oxide.

[0058] In the present invention, the second catalyst preferably comprises PtAu / CeO 2 or PtRu / CeO 2 , more preferably PtRu / CeO 2 In the specific embodiment of the present invention, PtRu / CeO 2 The Pt loading is 2 wt% and the Ru loading is 1 wt%.

[0059] In the present invention, the molar ratio of the active metal to the intermediate product in the second catalyst is preferably 1:300 to 1:2000, more preferably 1:400 to 800, and further preferably 1:500 to 600.

[0060] In the present invention, the second solvent is water or acetic acid. In a specific embodiment of the present invention, the second solvent is water.

[0061] In the present invention, the mass of the intermediate product preferably accounts for 1-5% of the total mass of the intermediate product and the second solvent, more preferably 2-4%, and further preferably 3%.

[0062] In the present invention, the temperature of the oxidation reaction is preferably 50 to 120°C, more preferably 70 to 90°C, and the time is preferably 5 to 12 hours, more preferably 8 to 10 hours. 2 The pressure is preferably 0.5 to 6 MPa, more preferably 1 to 3 MPa. In the oxidation reaction, cyclopentanone is converted into glutaric acid under the action of a catalyst and oxygen.

[0063] In the present invention, after the oxidation reaction, the oxidation product is preferably subjected to solid-liquid separation to obtain glutaric acid.

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments below. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Any modification, equivalent replacement, improvement, etc. made to the implementation methods of the present invention based on the technical essence and general principles of the present invention without creative work should be within the scope of protection of the present invention.

[0065] Preparation of the first catalyst

[0066] Weigh 10g SiO 2 (Al 2 O 3 or ZrO 2 ) is dispersed in 100 mL of water, a Pt precursor (Ni precursor or Co precursor) is weighed so that the calculated Pt (Ni or Co) loading is 2 wt %, the Pt precursor (Ni precursor or Co precursor) is dissolved in 50 mL of water to obtain a Pt precursor aqueous solution (Ni precursor aqueous solution or Co precursor aqueous solution), and the Pt precursor aqueous solution (Ni precursor aqueous solution or Co precursor aqueous solution) is slowly dripped into the SiO 2 Suspension (Al 2 O 3 Suspension or ZrO 2 The solid was filtered and washed, then dried at 70°C for 12 hours. The dried solid was ground and calcined in a muffle furnace at 400°C for 5 hours. The calcined solid powder was transferred to a tube furnace and 10% H 2 / 90% Ar mixed gas was reduced at 400°C for 5h to obtain the catalyst.

[0067] Weigh 10g SiO 2Disperse into 100 mL of water, weigh Pt precursor and Cu precursor (Pt precursor and Ni precursor, Pt precursor and Pd precursor), so that the calculated Pt loading is 2 wt%, Cu (Ni or Pd) loading is 2 wt%, dissolve Pt precursor and Cu precursor (Pt precursor and Ni precursor, Pt precursor and Pd precursor) in 50 mL of water to obtain Pt-Cu precursor aqueous solution (Pt-Ni precursor aqueous solution or Pt-Pd precursor aqueous solution), slowly drop the Pt-Cu precursor aqueous solution (Pt-Ni precursor aqueous solution or Pt-Pd precursor aqueous solution) into SiO 2 At the same time, 0.2 mol / L NaOH solution was added dropwise to the suspension. After the addition was completed, the suspension was stirred for 4 hours. The resulting suspension was allowed to stand for one day. The solid was filtered and washed, then dried at 70°C for 12 hours. The dried solid was ground and calcined in a muffle furnace at 400°C for 5 hours. The calcined solid powder was transferred to a tube furnace and 10% H 2 / 90% Ar mixed gas was reduced at 400°C for 5h to obtain the catalyst.

[0068] Weigh 10g SiO 2 Disperse into 100 mL of water, weigh Fe precursor and Cu precursor, so that the calculated Fe loading is 2 wt% and Cu loading is 2 wt%, dissolve Fe precursor and Cu precursor in 50 mL of water to obtain Fe-Cu precursor aqueous solution, and slowly drip the Fe-Cu precursor aqueous solution into SiO 2 At the same time, 0.2 mol / L NaOH solution was added dropwise to the suspension. After the addition was completed, the suspension was stirred for 4 hours. The resulting suspension was allowed to stand for one day. The solid was filtered and washed, then dried at 70°C for 12 hours. The dried solid was ground and calcined in a muffle furnace at 400°C for 5 hours. The calcined solid powder was transferred to a tube furnace and 10% H 2 / 90% Ar mixed gas was reduced at 400°C for 5h to obtain the catalyst.

[0069] Preparation of the second catalyst

[0070] Weigh 10g CeO 2 (SiO 2or C) is dispersed in 100 mL of ethanol, a Pt precursor (Ni precursor, Cu precursor, Au precursor or Co precursor) is weighed so that the calculated Pt (Ni, Cu, Au or Co) loading is 2 wt %, the Pt precursor (Ni precursor, Cu precursor, Au precursor or Co precursor) is dissolved in 50 mL of water to obtain a Pt precursor aqueous solution (Ni precursor aqueous solution, Cu precursor aqueous solution, Au precursor aqueous solution or Co precursor aqueous solution), and the Pt precursor aqueous solution (Ni precursor aqueous solution, Cu precursor aqueous solution, Au precursor aqueous solution or Co precursor aqueous solution) is slowly dripped into the CeO 2 Suspension (SiO 2 The solid was filtered and washed, then dried at 70°C for 12h. The dried solid was ground and calcined at 300°C in a muffle furnace for 4h. The calcined solid powder was transferred to a tube furnace and passed through 10% H 2 / 90% Ar mixed gas was reduced at 300°C for 4h to obtain the catalyst.

[0071] Weigh 10g CeO 2 Dispersed in 100 mL of ethanol, weighed Pt precursor and Co precursor (Pt precursor and Au precursor, Pt precursor and Ru precursor), so that the calculated Pt loading is 2 wt%, CO (Au or Ru) loading is 1 wt%, Pt precursor and Co precursor (Pt precursor and Au precursor, Pt precursor and Ru precursor) are dissolved in 50 mL of water to obtain Pt-Co precursor aqueous solution (Pt-Au precursor aqueous solution or Pt-Ru precursor aqueous solution), and the Pt-Co precursor aqueous solution (Pt-Au precursor aqueous solution or Pt-Ru precursor aqueous solution) is slowly dripped into CeO 2 At the same time, 0.2 mol / L NaOH solution was added dropwise to the suspension, and the mixture was stirred for 4 hours after the addition was completed. The resulting suspension was allowed to stand for one day. The solid was filtered and washed, and then dried at 70°C for 12 hours. The dried solid was ground and calcined at 300°C in a muffle furnace for 4 hours. The calcined solid powder was transferred to a tube furnace and 10% H 2 / 90% Ar mixed gas was reduced at 300°C for 4h to obtain the catalyst.

[0072] Selection of the first catalyst in furfural hydrogenation

[0073] In a 25 mL stainless steel high pressure reactor, 0.43 g furfural, 0.1 g first catalyst, 0.0043 g p-phenol and water were added to a total reaction volume of 15 mL. After sealing the reactor, H 210MPa, heated to 170℃ for 3h, cooled to room temperature after the reaction, and took out the reaction solution. The product types and concentrations were analyzed by HPLC, as shown in Table 1. The conversion rate and selectivity were calculated by the following formula:

[0074] Conversion rate = (initial molar concentration of reactants - final molar concentration of reactants) / initial molar concentration of reactants

[0075] ×100% (Formula 1)

[0076] Selectivity = target product final molar concentration / (initial molar concentration of reactants - final molar concentration of reactants)

[0077] ×100% (Formula 2)

[0078] The catalyst used was Ni / SiO with a Ni loading of 2 wt%. 2 , Co / SiO with Co loading of 2wt% 2 , CuFe / SiO with 2wt% Cu loading and 2wt% Fe loading 2 , Pt / SiO with a Pt loading of 2wt% 2 , Pt loading of 2wt% Pt / Al 2 O 3 , Pt / ZrO with 2wt% Pt loading 2 , PtCu / SiO with 2wt% Pt loading and 2wt% Cu loading 2 , PtNi / SiO with 2wt% Pt loading and 2wt% Ni loading 2 , PtPd / SiO with 2wt% Pt loading and 2wt% Pd loading 2 The obtained products were furfuryl alcohol (FFA), cyclopentanone (CPO), 2-methylfuran (2-MF), 1,2-pentanediol (1,2-PeD) and 1,5-pentanediol (1,5-PeD).

[0079] Table 1 Selectivity of products and conversion of reactants under different catalyst conditions in furfural hydrogenation reaction

[0080]

[0081]

[0082] As can be seen from Table 1, among the single metal catalysts, the conversion rate of furfural and the selectivity for cyclopentanone of the Pt-based catalyst are both at a relatively high level; and compared with the single metal catalyst, the performance of the bimetallic catalyst is better. In the case of the same carrier, the introduction of a second metal Pd into the Pt-based catalyst can greatly improve the selectivity of the catalyst, and the selectivity for cyclopentanone can reach 80.3%. Although the introduction of a second metal Cu into the Pt-based catalyst can improve the selectivity of the catalyst for cyclopentanone, the conversion rate of furfural will decrease. Although in Al 2 O 3 and ZrO 2 When used as a carrier, Pt-based monometallic catalysts also have good conversion rates and selectivity, but the selectivity of by-products such as furfuryl alcohol and 2-methylfuran is also relatively high, which will affect the reaction in the second step.

[0083] Selection of solvent in furfural hydrogenation reaction

[0084] In a 25 mL stainless steel high pressure reactor, 0.43 g furfural, 0.1 g PtPd / SiO 2 , 0.0043 g of p-phenol and solvent, the total reaction volume was 15 mL, the reactor was sealed and filled with H 2 10MPa, heated to 170℃ for 3h, cooled to room temperature after the reaction, and took out the reaction solution. The product types and concentrations were analyzed by HPLC, as shown in Table 2. The solvents used were water, isopropanol, acetonitrile, toluene and acetone.

[0085] Table 2 Selectivity of products and conversion of reactants under different organic solvent conditions in furfural hydrogenation reaction

[0086]

[0087] As can be seen from Table 2, when water and acetonitrile are used as solvents, the selectivity for cyclopentanone is above 70%, and the furfural conversion rate is above 75%. When water is used as solvent, the selectivity for cyclopentanone and the furfural conversion rate are the best. This is because water as solvent can provide a suitable concentration of H + , which is beneficial to the isomerization reaction and the formation of the final product CPO.

[0088] Selection of the Second Catalyst in the Oxygenation Reaction of Cyclopentanone

[0089] In a 25 mL stainless steel high pressure reactor, 0.17 g cyclopentanone, 0.1 g second catalyst, and acetic acid were added as solvent. The total reaction volume was 15 mL. After sealing the reactor, O 21MPa, heated to 50℃ for 3h, cooled to room temperature after the reaction, and took out the reaction solution. The yield of glutaric acid (GA) was analyzed by high performance liquid chromatography, as shown in Table 3. The catalyst used was Ni / CeO with a Ni loading of 2wt%. 2 , Co / CeO with 2wt% Co loading 2 , Cu / CeO with Cu loading of 2wt% 2 , Au / CeO with 2wt% Au loading 2 , Pt / SiO with a Pt loading of 2wt% 2 , Pt / CeO with 2wt% Pt loading 2 , Pt / C with 2wt% Pt loading, PtCo / CeO with 2wt% Pt loading and 1wt% Co loading 2 , Pt loading 2wt%, Au loading 1wt% PtAu / CeO 2 , PtRu / CeO with 2wt% Pt loading and 1wt% Ru loading 2 .

[0090] Table 3 Yield of glutaric acid and conversion of furfural under different catalyst conditions in cyclopentanone oxygenation reaction

[0091] catalyst Conversion rate (%) GA yield (%) <![CDATA[Ni / CeO 2 ]]> 13.6 2.1 <![CDATA[Co / CeO 2 ]]> 15.9 5.6 <![CDATA[Cu / CeO 2 ]]> 9.1 0 <![CDATA[Au / CeO 2 ]]> 20.3 10.2 <![CDATA[Pt / CeO 2 ]]> 78.3 58.1 <![CDATA[Pt / SiO 2 ]]> 23.6 13.4 Pt / C 68.1 30.5 <![CDATA[PtCo / CeO 2 ]]> 80.5 78.8 <![CDATA[PtAu / CeO 2 ]]> 90.3 89.1 <![CDATA[PtRu / CeO 2 ]]> 95.1 93.3

[0092] It can be seen from Table 3 that among the single metal catalysts, Pt / CeO 2 The conversion rate and yield of the catalyst are the best. 2 The catalytic performance of Pt-based catalysts is better than that of SiO 2 Based on the above two reasons, the first metal of the catalyst is selected as Pt, and CeO 2 Based on the conclusion that the performance of the bimetallic catalyst obtained by the previous catalyst screening is better than that of the single metal catalyst, the Pt / CeO 2 The catalyst introduces a second metal. Through testing, it is found that when Ru is added as the second metal to obtain the PtRu bimetallic catalyst, the yield of glutaric acid can reach 93.3%, and the conversion rate can reach 95.1%.

[0093] Selection of solvent in the oxygenation reaction of cyclopentanone

[0094] In a 25 mL stainless steel high pressure reactor, 0.17 g cyclopentanone, 0.1 g PtRu / CeO 2 and solvent, the total reaction volume was 15 mL, the reactor was sealed, and O 21MPa, heated to 50°C for 3h, cooled to room temperature after the reaction, and the reaction solution was taken out. The yield of glutaric acid (GA) was analyzed by high performance liquid chromatography, as shown in Table 4. The solvents used were water, acetic acid, formic acid, propionic acid and acetone.

[0095] Table 4 Yield of glutaric acid and conversion of furfural under different solvent conditions in cyclopentanone oxygenation reaction

[0096] Solvents Conversion rate (%) GA yield (%) water 87.5 80.1 acetic acid 95.1 93.3 Formic acid 65.1 60.3 acetone 78.4 34.1 Propionic acid 80.3 78.2

[0097] As can be seen from Table 4, the GA yields in water and acetic acid are significantly higher, and water is preferred as the solvent due to the corrosiveness of acetic acid.

[0098] Furfural aqueous solution with different mass concentrations

[0099] Example 1

[0100] 15 mL of 5 wt% furfural aqueous solution, 0.1 g of PtPd / SiO 2 and 0.05% of the mass of furfural and p-phenol were mixed and added into the first reactor, and 0.1 g of PtRu / CeO with a Pt loading of 2 wt% and a Ru loading of 1 wt% was added. 2 Add to the second reactor, the first reactor and the second reactor are connected in series, and after sealing, H is charged into the first reactor. 2 10MPa, fill the second reactor with O 2 1MPa. The reaction temperature of the first reactor was set to 170°C for 3h, and the reaction temperature of the second reactor was set to 50°C for 8h. After the reaction was completed, the reaction solution was taken out after cooling to room temperature, and the yield of glutaric acid (GA) and the conversion rate of furfural were analyzed by high performance liquid chromatography. The yield of glutaric acid was calculated by the following formula:

[0101] Glutaric acid yield = glutaric acid molar concentration / furfural initial molar concentration × 100% (Formula 3)

[0102] Example 2

[0103] 15 mL of 1 wt% furfural aqueous solution was added into the first reactor. Other conditions were the same as those in Example 1.

[0104] Example 3

[0105] 15 mL of 3 wt% furfural aqueous solution was added into the first reactor. Other conditions were the same as those in Example 1.

[0106] Comparative Example 1

[0107] 15 mL of 10 wt% furfural aqueous solution was added into the first reactor. Other conditions were the same as those in Example 1.

[0108] Table 5 Yield of glutaric acid and conversion rate of furfural under different furfural aqueous solutions

[0109] Conversion rate (%) GA yield (%) Example 1 84.7 64.3 Example 2 99.8 77.8 Example 3 99.7 75.6 Comparative Example 1 62.1 43.2

[0110] It can be seen from Table 5 that the yield of glutaric acid decreases with the increase of furfural feed concentration. High concentration of furfural will cause polymerization side reaction, thus resulting in a decrease in the yield of glutaric acid.

[0111] Different reaction temperatures

[0112] Example 4

[0113] The reaction temperature of the first reactor was set to 170° C., and the reaction temperature of the second reactor was set to 80° C. Other conditions were the same as those in Example 1.

[0114] Example 5

[0115] The reaction temperature of the first reactor was set to 170° C., and the reaction temperature of the second reactor was set to 120° C. Other conditions were the same as those in Example 1.

[0116] Example 6

[0117] The reaction temperature of the first reactor was set to 200° C., and the reaction temperature of the second reactor was set to 50° C. Other conditions were the same as those in Example 1.

[0118] Comparative Example 2

[0119] The reaction temperature of the first reactor was set to 170° C., and the reaction temperature of the second reactor was set to 30° C. Other conditions were the same as those in Example 1.

[0120] Comparative Example 3

[0121] The reaction temperature of the first reactor was set to 130°C, and the reaction temperature of the second reactor was set to 50°C.

[0122] Other conditions are the same as in Example 1

[0123] Table 6 Yield of glutaric acid and conversion rate of furfural at different reaction temperatures

[0124] The first stage reaction temperature The second stage reaction temperature Conversion rate (%) GA yield (%) Example 1 170℃ 50℃ 84.7 64.3 Example 4 170℃ 80℃ 83.8 70.3 Example 5 170℃ 120℃ 99.6 68.2 Example 6 200℃ 50℃ 92.5 67.3 Comparative Example 2 170℃ 30℃ 83.7 36.7 Comparative Example 3 130℃ 50℃ 70.3 60.1

[0125] As can be seen from Table 6, the reaction temperature of the first reactor affects the yield of cyclopentanone and thus the final yield of glutaric acid. The reaction temperature of the second reactor affects the yield of glutaric acid. Too high a temperature easily leads to decarboxylation of glutaric acid, thereby reducing the yield, and also leads to oxidation of unreacted furfural in the first step to generate furanone products.

[0126] Different reaction times

[0127] Example 7

[0128] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 1 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 8 h. Other conditions were the same as those in Example 1.

[0129] Example 8

[0130] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 2 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 8 h. Other conditions were the same as those in Example 1.

[0131] Example 9

[0132] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 5 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 8 h. Other conditions were the same as those in Example 1.

[0133] Example 10

[0134] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 3 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 5 h. Other conditions were the same as those in Example 1.

[0135] Embodiment 11

[0136] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 3 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 10 h. Other conditions were the same as those in Example 1.

[0137] Example 12

[0138] The reaction temperature of the first reactor was set to 170° C. and the reaction time was set to 3 h, and the reaction temperature of the second reactor was set to 80° C. and the reaction time was set to 12 h. Other conditions were the same as those in Example 1.

[0139] Comparative Example 4

[0140] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 hours, and the reaction temperature of the second reactor was set to 80°C and the reaction time was 8 hours. Other conditions were the same as those in Example 1

[0141] Table 7 Yield of glutaric acid and conversion rate of furfural at different reaction times

[0142]

[0143] As can be seen from Table 7, it can be found that when the temperature and time of the second stage reaction are the same, the yield of glutaric acid increases with the increase of the first stage reaction time, which is mainly caused by the yield of cyclopentanone generated in the first stage. The long first stage reaction time will lead to excessive hydrogenation of cyclopentanone to generate cyclopentanol. It can be found that when the temperature and time of the first stage reaction are the same, increasing the time of the second stage oxidation (cyclopentanol needs to be oxidized to generate cyclopentanone first) will lead to a slight decrease in the yield of glutaric acid, and too long a reaction time will also lead to a decarboxylation side reaction of glutaric acid and a polycondensation reaction between keto acids.

[0144] Different reaction pressure

[0145] Example 13

[0146] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 h. The reaction temperature of the second reactor was set to 80°C and the reaction time was 10 h. H 2 5MPa, fill the second reactor with O 2 1MPa. Other conditions are the same as those in Example 1.

[0147] Embodiment 14

[0148] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 h. The reaction temperature of the second reactor was set to 80°C and the reaction time was 10 h. H 2 10MPa, fill the second reactor with O 2 0.5MPa. Other conditions are the same as those in Example 1.

[0149] Embodiment 15

[0150] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 h. The reaction temperature of the second reactor was set to 80°C and the reaction time was 10 h. H 2 10MPa, fill the second reactor with O 2 1MPa. Other conditions are the same as those in Example 1.

[0151] Example 16

[0152] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 h. The reaction temperature of the second reactor was set to 80°C and the reaction time was 10 h. H 2 10MPa, fill the second reactor with O 26MPa. Other conditions are the same as those in Example 1.

[0153] Embodiment 17

[0154] The reaction temperature of the first reactor was set to 170°C and the reaction time was 3 h. The reaction temperature of the second reactor was set to 80°C and the reaction time was 10 h. H 2 20MPa, fill the second reactor with O 2 1MPa. Other conditions are the same as those in Example 1.

[0155] Table 8 Yield of glutaric acid and conversion rate of furfural under different reaction pressures

[0156] <![CDATA[H 2 Pressure(MPa)]]> <![CDATA[O 2 Pressure(MPa)]]> Conversion rate (%) GA yield (%) Example 13 5 1 85.8 75.8 Embodiment 14 10 0.5 87.2 64.1 Embodiment 15 10 1 87.8 75.4 Example 16 10 6 89.4 78.5 Embodiment 17 20 1 88.4 73.6

[0157] As can be seen from Table 8, the effect of reaction pressure on the yield of glutaric acid is not obvious.

[0158] 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 synthesizing glutaric acid, characterized in that: The following steps are involved: The furfural, the polymerization inhibitor, the first catalyst and the first solvent are mixed, and H2 is introduced under closed conditions to carry out a hydrogenation reaction to obtain an intermediate product containing cyclopentanone; The intermediate product containing cyclopentanone is mixed with a second catalyst and a second solvent, and O2 is introduced under closed conditions to carry out an oxidation reaction to obtain the glutaric acid; The first catalyst and the second catalyst include a carrier and an active metal; The active metal in the first catalyst is one or more of Ni, Co, Fe, Cu, Au, Pt, Pd, and Rh; The active metal in the second catalyst is one or more of Ni, Co, Cu, Au, Pt, Pd and Ru; The carriers in the first catalyst and the second catalyst are independently silicon dioxide, aluminum oxide, zirconium oxide, cerium oxide or activated carbon; The first solvent is water or acetonitrile; The second solvent is water or acetic acid; The temperature of the hydrogenation reaction is 170-200°C and the time is 3-5h; The oxidation reaction temperature is 50-120°C and the time is 5-12h; The mass of the furfural accounts for 1-5% of the total mass of the furfural and the first solvent.

2. The synthesis method according to claim 1, characterized in that In the first catalyst and the second catalyst, the loading amount of the active metal on the carrier is independently 1 to 10% of the weight of the carrier.

3. The synthesis method according to claim 1 or 2, characterized in that The first catalyst includes Pt / SiO2, Pt / Al2O3, Pt / ZrO2, PtNi / SiO2 or PtPd / SiO2.

4. The synthesis method according to claim 1 or 2, characterized in that The second catalyst includes PtAu / CeO2 or PtRu / CeO2.

5. The synthesis method according to claim 1, characterized in that The molar ratio of the active metal to furfural in the first catalyst is 1:300-2000.

6. The synthesis method according to claim 1, characterized in that The molar ratio of the active metal in the second catalyst to the cyclopentanone in the intermediate product containing cyclopentanone is 1:300-2000.

7. The synthesis method according to claim 1, characterized in that The polymerization inhibitor is hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol or a quinone polymerization inhibitor.

8. The synthesis method according to claim 1 or 7, characterized in that: The mass of the inhibitor accounts for 0.01-0.1% of the mass of furfural.

9. The synthesis method according to claim 1, characterized in that The pressure of the H2 introduced is 5 to 20 MPa.

10. The synthesis method according to claim 1, characterized in that The pressure of the introduced O2 is 0.5-6MPa.

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