Method and system for efficiently synthesizing diphenyl carbonate

Abstract

The invention relates to the technical field of organic chemical synthesis, in particular to a method and a system for efficiently synthesizing diphenyl carbonate. The method comprises the following steps: taking phenol and carbonic ester as raw materials, taking a multi-metal vanadium oxide compound as a catalyst, and reacting in a high-temperature reaction kettle with a mechanical stirring and condensation reflux device and a kettle bottom gas distributor; carbonic ester is continuously injected from the bottom of the high-temperature reaction kettle along with inert carrier gas, unreacted carbonic ester is refluxed through fractional condensation, and a byproduct alcohol is discharged along with the inert carrier gas; the carbonic ester is dimethyl carbonate or diethyl carbonate; the dosage of the catalyst is 0.5-5wt% of the mass of the phenol raw material According to the invention, through continuous feeding and specific condensation temperature control, selective condensation reflux of raw materials (carbonic ester) and selective removal of by-products (alcohols) are realized, reversible balance of ester exchange reaction is effectively broken, forward proceeding of the reaction is greatly promoted, and phenol conversion rate and reaction efficiency are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis technology, and in particular to a method and system for the efficient synthesis of diphenyl carbonate. Background Technology

[0002] Diphenyl carbonate (DPC) is a key raw material for the synthesis of polycarbonate, and its green and clean production process is of great significance to the development of non-phosgene synthesis routes for polycarbonate. The preparation of DPC via transesterification is currently a highly representative process route and is widely recognized as a typical example of green and sustainable production in the chemical industry.

[0003] Traditional transesterification synthesis of DPC often employs batch or semi-batch operation in a batch-type reactor, with raw materials added all at once or in batches. This method has the following disadvantages: (1) The reaction is a reversible equilibrium reaction. If the generated methanol or ethanol is not removed in time, it will inhibit the forward reaction, resulting in low phenol conversion and DPC selectivity; (2) The catalyst is easily deactivated during the reaction and is difficult to separate from the product; (3) The reactants are not mixed sufficiently, and the reaction efficiency needs to be improved; (4) The removal of by-product alcohols usually depends on distillation, which consumes a lot of energy.

[0004] Patent CN207371131U describes a reactive condensation distillation production apparatus, providing a solution for dimethyl carbonate reflux and methanol separation. However, this apparatus is structurally complex due to the integration of condensation and distillation equipment. Furthermore, the large-scale vaporization and reflux of dimethyl carbonate not only increases energy consumption but also further raises production costs.

[0005] Therefore, in order to improve reaction efficiency and promote the forward shift of reaction equilibrium, a continuous synthesis method is needed that can efficiently remove small molecule byproduct alcohols, enhance gas-liquid contact, reduce energy consumption, and achieve efficient utilization of catalysts. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method and system for the efficient synthesis of diphenyl carbonate. This method breaks the thermodynamic equilibrium constraint through reaction-distillation coupling, and a multi-metal vanadium oxide complex catalyst efficiently suppresses the anisole side reaction, achieving high conversion and high selectivity in the synthesis of diphenyl carbonate.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for efficiently synthesizing diphenyl carbonate, which uses phenol and carbonate as raw materials and a multi-metal vanadium oxide complex as a catalyst, reacts in a high-temperature reactor equipped with a mechanical stirrer, a reflux condenser and a bottom gas distributor; the carbonate is continuously injected into the bottom of the high-temperature reactor with an inert carrier gas, and the unreacted carbonate is refluxed by staged condensation, while the byproduct alcohol is discharged with the inert carrier gas.

[0009] The carbonate is dimethyl carbonate or diethyl carbonate;

[0010] The amount of catalyst used is 0.5~5 wt% of the phenol raw material.

[0011] The specific steps of the method for efficiently synthesizing diphenyl carbonate are as follows:

[0012] S1: Feeding and Replacement: Phenol and catalyst are added to the high-temperature reactor beforehand, the inert carrier gas valve is opened, and inert carrier gas is introduced from the gas distributor to replace the gas in the high-temperature reactor and remove the air.

[0013] S2: Heating: Under an inert carrier gas atmosphere, start stirring and heat the high-temperature reactor to 120~180℃;

[0014] S3: Continuous feeding and reaction: Liquid carbonate is pumped in by a metering pump, merged with inert carrier gas from the bottom, and continuously injected into the bottom of the liquid layer of the high-temperature reactor in a bubbling form through a gas distributor.

[0015] S4: Product removal and reflux: The carbonate gas-liquid mixture injected into the bottom of the liquid layer of the high-temperature reactor is rapidly heated and vaporized under stirring; during the rising process, the carbonate vapor and phenol liquid come into full contact on the catalyst surface and undergo transesterification reaction; the generated byproduct alcohol and unreacted carbonate vapor enter the condensation and reflux device together with the inert carrier gas.

[0016] S5: Condensation separation: Selective separation and reflux of products are achieved by controlling the condensation temperature of the condensation reflux device; carbonate vapor is condensed and refluxed to the high-temperature reactor to continue the reaction, and the by-product alcohol enters the subsequent collection device with the inert carrier gas;

[0017] S6: Reaction Termination: When the phenol conversion rate reaches the predetermined requirement (e.g., >90%), stop feeding and end the reaction.

[0018] In step S3, the molar ratio of the carbonate injection rate to the initial amount of phenol in the high-temperature reactor is controlled at 0.025~0.125 mol / mol / h, and the ratio of the inert carrier gas flow rate to the initial amount of phenol in the reactor is controlled at 300~2000 mL / mol / h.

[0019] In step S3, carbonate is continuously fed for 4 to 20 hours, and the cumulative molar ratio of carbonate to initial phenol is greater than 0.5:1.

[0020] In step S5, the condensation temperature is 70-80℃ when the raw material is dimethyl carbonate and 90-100℃ when the raw material is diethyl carbonate.

[0021] The polymetallic vanadium oxide complex is MVO x M contains at least two metallic elements selected from Fe, Bi, Al, Zn, Ni, and Zr.

[0022] The multimetallic vanadium oxide complex was prepared by a hydrothermal method, and the specific preparation process is as follows:

[0023] 1) Raw material preparation: Ammonium vanadate is used as the vanadium source to prepare an ammonium vanadate solution; a mixture of nitrates is used as the metal source to prepare a metal salt solution;

[0024] 2) Mixing and adjustment: Add the metal salt solution dropwise to the ammonium vanadate solution, stir evenly, and then adjust the pH of the mixture to the range of 2-7 using NaOH solution;

[0025] 3) Hydrothermal reaction: The pH-adjusted mixture is placed in a hydrothermal environment, and the hydrothermal temperature is controlled at 160~200℃ for a reaction time of 6~24h;

[0026] 4) Post-processing: The product after hydrothermal reaction is centrifuged, washed with water, dried at 80~100℃ for 6~12h, and then calcined at 200~300℃ for 2~4h to obtain the polymetallic vanadium oxide composite.

[0027] The concentration of the metal salt solution is 0.1~0.5 mol / L;

[0028] The molar ratio of total metal ions to vanadium in the nitrate mixture is 0.5~1.3:1.

[0029] The metal salt solution is added to the ammonium vanadate solution at a dropping rate of 1~5 mL / min, the stirring rate is 300~500 r / min, and the stirring time is 30~60 min.

[0030] A system for the efficient synthesis of diphenyl carbonate includes a high-temperature reactor, a reflux condenser, and a gas distributor; the reflux condenser is located at the top of the high-temperature reactor, and the gas distributor is located at the bottom inside the high-temperature reactor.

[0031] The high-temperature reactor is equipped with an inlet pipe and a feed pipe at its bottom, with the inlet pipe connected to the gas distributor. The feed pipe and the inlet pipe merge before entering the gas distributor.

[0032] The high-temperature reactor is equipped with a jacketed heating device on its exterior and a mechanical stirring device on its interior.

[0033] The high-temperature reactor is also equipped with a bottom sampling tube;

[0034] The system for the efficient synthesis of diphenyl carbonate further includes a secondary condenser and a secondary condensation collection device. The secondary condenser is connected to the condensation reflux device, and the secondary condensation collection device is connected to the secondary condenser.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) The synthesis method of the present invention breaks the reaction equilibrium and improves the reaction efficiency: The present invention achieves “selective reflux of raw material (carbonate) and selective removal of by-product (alcohol)” through continuous feeding and specific condensation temperature control, effectively breaking the reversible equilibrium of the transesterification reaction, greatly promoting the forward reaction, and significantly improving the phenol conversion rate and reaction efficiency.

[0037] (2) The synthesis method of the present invention enhances mass transfer and mixing: The present invention adopts the method of continuous injection of carbonate with inert carrier gas at the bottom of the vessel, combined with mechanical stirring, so that the raw materials are dispersed in the form of micro bubbles / droplets, which greatly increases the gas-liquid contact area, enhances the mass transfer process, and makes the reaction faster and more complete.

[0038] (3) The synthesis method of the present invention is continuous and stable in operation and easy to scale up: The synthesis method of the present invention realizes the continuous and controllable addition of raw materials and the continuous removal of by-products. The process is stable and easy to automate and scale up to industrial scale.

[0039] (4) The synthesis method of the present invention has high catalyst utilization efficiency: the solid composite catalyst is in full contact with the raw materials in the reaction vessel, and the reaction conditions are mild, which is conducive to extending the catalyst life and improving its utilization efficiency.

[0040] (5) Energy consumption and by-product value of the synthesis method of the present invention: The process of removing alcohol by-products mainly relies on phase change separation rather than distillation, resulting in lower energy consumption. At the same time, the collected methanol or ethanol has high purity and can be used as valuable by-products, thus improving the economic efficiency of the process.

[0041] (6) The present invention uses a small amount of continuous bottom-distributed carbonate feed to make its single-pass conversion more complete, reduce the amount of vaporization, reduce the energy consumption of reaction heating and condensation reflux, and further reduce production costs. Attached Figure Description

[0042] Figure 1 This is an overall schematic diagram of the system for the efficient synthesis of diphenyl carbonate according to the present invention.

[0043] The attached figures are labeled as follows: 100-high temperature reactor, 200-condensation reflux device, 300-gas distributor, 400-secondary condenser, 500-secondary condensation collection device, 110-inlet pipeline; 120-feed pipeline; 130-mechanical stirring device, 140-bottom sampling pipe, 001-inert carrier gas valve, 002-metering pump. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0045] See Figure 1 This invention provides a method for the efficient synthesis of diphenyl carbonate, which uses phenol and carbonate as raw materials and a multi-metal vanadium oxide complex as a catalyst. The reaction is carried out in a high-temperature reactor 100 equipped with a mechanical stirrer 130, a reflux condenser 200 and a bottom gas distributor 300 (reaction temperature is 120~180℃). The carbonate is continuously injected from the bottom of the high-temperature reactor 100 with an inert carrier gas. Unreacted carbonate is refluxed through staged condensation, and the by-product alcohol is discharged with the inert carrier gas.

[0046] The carbonate is dimethyl carbonate or diethyl carbonate, and the inert carrier gas can be N2 or argon.

[0047] The catalyst dosage is 0.5-5 wt% of the phenol raw material, preferably 0.5-3.0 wt%.

[0048] Specifically, the specific steps of the method for efficiently synthesizing diphenyl carbonate are as follows:

[0049] S1: Feeding and Replacement: Phenol and catalyst are added to the high-temperature reactor 100 beforehand. The inert carrier gas valve 001 is opened, and inert carrier gas is introduced from the gas distributor 300 to replace the gas in the high-temperature reactor 100 and remove the air.

[0050] S2: Heating: Under an inert carrier gas atmosphere, turn on the stirrer and heat the high-temperature reactor 100 to the reaction temperature, i.e., 120~180℃.

[0051] S3: Continuous feeding and reaction: The raw material liquid carbonate is pumped in by metering pump 002, which merges with the inert carrier gas from the bottom, and is continuously injected into the bottom of the liquid layer of the high-temperature reactor 100 in the form of bubbling through gas distributor 300.

[0052] S4: Product removal and reflux: The carbonate gas-liquid mixture injected into the bottom of the liquid layer of the high-temperature reactor 100 is rapidly heated and vaporized under stirring; during the rising process, the carbonate vapor and phenol liquid come into full contact on the catalyst surface and undergo transesterification reaction; the generated byproduct alcohol (methanol or ethanol) and unreacted carbonate vapor enter the condensation and reflux device 200 along with the inert carrier gas.

[0053] S5: Condensation Separation: Selective separation and reflux of products are achieved by controlling the condensation temperature of the reflux condenser 200; carbonate vapor is condensed and refluxed back to the high-temperature reactor 100 to continue the reaction, and the by-product alcohol enters the subsequent collection device with the inert carrier gas; N2 and alcohol vapor discharged from the top of the reflux condenser 200 enter the secondary condenser 400 to condense the alcohol into a liquid product for collection; the recovered inert carrier gas obtained after separation can be recycled. When the raw material is dimethyl carbonate (DMC), the condensation temperature is controlled at 70~80℃, so that DMC is condensed and refluxed back to the high-temperature reactor 100 to continue the reaction, while methanol, which has a lower boiling point, remains in a gaseous state and enters the subsequent collection device with N2; when the raw material is diethyl carbonate (DEC), the condensation temperature is controlled at 90~100℃, so that DEC is condensed and refluxed, while ethanol remains in a gaseous state and is removed;

[0054] S6: Reaction Termination: When the phenol conversion rate reaches the predetermined requirement (e.g., >90%), stop feeding and end the reaction.

[0055] Preferably, in step S3, the molar ratio of the carbonate injection rate to the initial amount of phenol in the high-temperature reactor 100 is controlled at 0.025~0.125 mol / mol / h, and the ratio of the inert carrier gas flow rate to the initial amount of phenol in the reactor is controlled at 300~2000 mL / mol / h.

[0056] Preferably, in step S3, carbonate is continuously fed for 4 to 20 hours, and the cumulative molar ratio of carbonate to initial phenol is greater than 0.5:1.

[0057] Preferably, in step S5, the condensation temperature is 70~80℃ when the raw material is dimethyl carbonate and 90~100℃ when the raw material is diethyl carbonate.

[0058] Preferably, the multimetallic vanadium oxide complex is an iron-aluminum vanadium oxide complex (FeAlVO₄). x ), iron-bismuth-vanadium oxide complex (FeBiVO) x Nickel-aluminum-vanadium oxide complex (NiAlVO) x ) and bismuth zinc vanadium oxide complex (BiZnVO) x ) or iron-zinc-nickel-vanadium oxide complex (FeZnNiVO) x ), aluminum-zinc-nickel-vanadium oxide complex (AlZnNiVO) x One of them.

[0059] The catalyst was prepared using a hydrothermal method, and the specific preparation process is as follows:

[0060] 1) Raw material preparation: Ammonium vanadate is used as the vanadium source to prepare an ammonium vanadate solution; mixed nitrates (i.e., two or more nitrates) are used as the metal source to prepare a metal salt solution;

[0061] 2) Mixing and adjustment: Add the metal salt solution dropwise to the ammonium vanadate solution, stir evenly, and then adjust the pH of the mixture to the range of 2-7 using NaOH solution;

[0062] 3) Hydrothermal reaction: The pH-adjusted mixture is placed in a hydrothermal environment, and the hydrothermal temperature is controlled at 160~200℃ for a reaction time of 6~24h;

[0063] 4) Post-processing: The product after hydrothermal reaction is centrifuged, washed with water, dried at 80~100℃ for 6~12h, and then calcined at 200~300℃ for 2~4h to obtain the catalyst.

[0064] Preferably, the concentration of the metal salt solution is 0.1~0.5 mol / L;

[0065] The molar ratio of metal ions to vanadium in the mixed metal salt is 0.5~1.3:1.

[0066] Preferably, the metal salt solution is added to the ammonium vanadate solution at a dropping rate of 1~5 mL / min, the stirring rate is 300~500 r / min, and the stirring time is 30~60 min.

[0067] See Figure 1 The present invention also provides a system for the efficient synthesis of diphenyl carbonate, which includes a high-temperature reactor 100, a reflux condenser 200 and a gas distributor 300; the reflux condenser 200 is disposed at the top of the high-temperature reactor 100 and the gas distributor 300 is disposed at the bottom inside the high-temperature reactor 100.

[0068] The high-temperature reactor 100 is equipped with an inlet pipe 110 and a feed pipe 120 at its bottom. The inlet pipe 110 is connected to the gas distributor 300, and the feed pipe 120 merges with the inlet pipe 110 before entering the gas distributor 300. During use, fresh inert carrier gas enters through the inlet pipe 110, and the raw material carbonate enters through the feed pipe 120. The inert carrier gas and carbonate are mixed before entering the gas distributor 300, meaning the carbonate is continuously injected from the bottom of the high-temperature reactor 100 along with the inert carrier gas.

[0069] For an even better option, see [link to previous section]. Figure 1 The high-temperature reactor 100 is equipped with a jacketed heating device on its exterior and a mechanical stirring device 130 on its interior.

[0070] Preferably, the high-temperature reactor 100 is further provided with a bottom sampling tube 140; the composition of the reaction liquid can be sampled and analyzed in real time through the bottom sampling tube 140.

[0071] In addition, the system for the efficient synthesis of diphenyl carbonate also includes a secondary condenser 400 and a secondary condensation collection device 500, wherein the secondary condensation collection device 500 is used to collect the removed byproduct alcohol; the secondary condenser 400 is connected to the condensation reflux device 200; and the secondary condensation collection device 500 is connected to the secondary condenser 400.

[0072] Example 1: Preparation of iron-aluminum-vanadium oxide composite catalyst.

[0073] 1) Raw material preparation: Take 1.17g of ammonium vanadate, add 100mL of 70℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.1mol / L; take 3.03g of ferric nitrate nonahydrate and 0.938g of aluminum nitrate nonahydrate, add 50mL of deionized water, stir to dissolve to obtain a nitrate solution with a concentration of 0.2mol / L (M:V=1:1, molar ratio);

[0074] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 2 mL / min, while stirring at a rate of 400 r / min for 40 min. After stirring evenly, adjust the pH of the mixture to 3 with 0.1 mol / L NaOH solution.

[0075] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 170℃ and the reaction time at 12h.

[0076] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed three times with deionized water, then dried in an 85℃ oven for 8 hours, and finally placed in a muffle furnace and calcined in an air atmosphere at 250℃ for 3 hours to obtain the iron-aluminum-vanadium oxide composite catalyst.

[0077] Example 2: Preparation of iron-bismuth-vanadium oxide composite catalyst.

[0078] 1) Raw material preparation: Take 1.17g of ammonium vanadate, add 100mL of 80℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.10mol / L; take 2.02g of ferric nitrate nonahydrate and 2.43g of bismuth nitrate pentahydrate, add 50mL of deionized water, stir to dissolve to obtain a nitrate solution with a concentration of 0.20mol / L (M:V=1:1, molar ratio);

[0079] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 3 mL / min, while stirring at a rate of 350 r / min for 50 min. After stirring evenly, adjust the pH of the mixture to 5 with 0.1 mol / L NaOH solution.

[0080] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 180℃ and the reaction time at 18h.

[0081] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed three times with deionized water, then dried in a 90℃ oven for 10h, and finally placed in a muffle furnace and calcined in an air atmosphere at 280℃ for 2.5h to obtain the iron-bismuth-vanadium oxide composite catalyst.

[0082] Example 3: Preparation of nickel-aluminum-vanadium oxide composite catalyst.

[0083] 1) Raw material preparation: Take 1.4g of ammonium vanadate, add 100mL of 65℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.12mol / L; take 1.164g of nickel nitrate hexahydrate and 3.0g of aluminum nitrate nonahydrate, add 50mL of deionized water, stir to dissolve to obtain a nitrate solution with a concentration of 0.24mol / L (M:V=1:1, molar ratio);

[0084] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 1.5 mL / min, while stirring at a rate of 450 r / min for 35 min. After stirring evenly, adjust the pH of the mixture to 2 with 0.1 mol / L NaOH solution.

[0085] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 160℃ and the reaction time at 24h.

[0086] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed three times with deionized water, then dried in an 80℃ oven for 12 hours, and finally placed in a muffle furnace and calcined in an air atmosphere at 200℃ for 4 hours to obtain the nickel-aluminum-vanadium oxide composite catalyst.

[0087] Example 4: Preparation of bismuth zinc vanadium oxide complex catalyst.

[0088] 1) Raw material preparation: Take 1.87g of ammonium vanadate, add 100mL of 85℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.16mol / L; take 1.18g of zinc nitrate hexahydrate and 1.94g of bismuth nitrate pentahydrate, add 50mL of deionized water, stir to dissolve to obtain a nitrate solution with a concentration of 0.16mol / L (M:V=0.5:1, molar ratio);

[0089] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 4 mL / min, while stirring at a rate of 300 r / min for 60 min. After stirring evenly, adjust the pH of the mixture to 7 with 0.1 mol / L NaOH solution.

[0090] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 200℃ and the reaction time at 6 hours.

[0091] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed 3 times with deionized water, then dried in an oven at 100℃ for 6 hours, and finally placed in a muffle furnace and calcined in an air atmosphere at 300℃ for 2 hours to obtain the bismuth zinc vanadium oxide composite catalyst.

[0092] Example 5: Preparation of iron-zinc-nickel-vanadium oxide composite catalyst.

[0093] 1) Raw material preparation: Take 1.87g of ammonium vanadate, add 100mL of 85℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.16mol / L; take 5.17g of ferric nitrate nonahydrate, 0.95g of zinc nitrate hexahydrate, and 0.93g of nickel nitrate hexahydrate, add 100mL of deionized water, stir to dissolve, and obtain a nitrate solution with a concentration of 0.192mol / L (M:V=1.2:1, molar ratio);

[0094] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 4 mL / min, while stirring at a rate of 300 r / min for 60 min. After stirring evenly, adjust the pH of the mixture to 7 with 0.1 mol / L NaOH solution.

[0095] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 200℃ and the reaction time at 6 hours.

[0096] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed 3 times with deionized water, then dried in an oven at 100℃ for 6 hours, and finally placed in a muffle furnace and calcined in an air atmosphere at 300℃ for 2 hours to obtain the iron-zinc-nickel-vanadium oxide composite catalyst.

[0097] Example 6: Preparation of aluminum-zinc-nickel-vanadium oxide composite catalyst.

[0098] 1) Raw material preparation: Take 1.87g of ammonium vanadate, add 100mL of 85℃ hot water, stir until completely dissolved to obtain an ammonium vanadate solution with a concentration of 0.16mol / L; take 2.4g of aluminum nitrate nonahydrate, 0.95g of zinc nitrate hexahydrate, and 0.93g of nickel nitrate hexahydrate, add 100mL of deionized water, stir to dissolve to obtain a nitrate solution with a concentration of 0.128mol / L (M:V=0.8:1, molar ratio);

[0099] 2) Mixing and adjustment: Add the nitrate solution dropwise to the ammonium vanadate solution at a rate of 4 mL / min, while stirring at a rate of 300 r / min for 60 min. After stirring evenly, adjust the pH of the mixture to 7 with 0.1 mol / L NaOH solution.

[0100] 3) Hydrothermal reaction: Transfer the above mixture to a hydrothermal reactor, seal it, and place it in an oven. Control the hydrothermal temperature at 200℃ and the reaction time at 6 hours.

[0101] 4) Post-processing: After the reaction is completed, the reactor is cooled to room temperature, the product is taken out and centrifuged, washed 3 times with deionized water, then dried in an oven at 100℃ for 6 hours, and finally placed in a muffle furnace and calcined in an air atmosphere at 300℃ for 2 hours to obtain the aluminum-zinc-nickel-vanadium oxide composite catalyst.

[0102] Example 7:

[0103] In a 500 mL high-temperature reactor 100 equipped with a mechanical stirrer 130 and a reflux condenser 200, 188 g (2.0 mol) of phenol and 3.76 g (2.0% of the phenol mass) of an iron-aluminum-vanadium oxide composite catalyst were added. After sealing, N2 was introduced from the bottom to purge the air three times. Under N2 protection, the mechanical stirrer 130 was turned on (300 rpm), and the temperature was raised to 150 °C. Metering pump 002 was turned on, and DMC was pumped in at a rate of 0.25 mol / h (i.e., DMC feed rate / initial phenol moles = 0.125 mol / mol / h). Simultaneously, the DMC feed pipe was mixed with N2 from the cylinder (flow rate 50 mL / min) before entering the gas distributor 300 at the bottom of the reactor, carrying the DMC into the reactor. The temperature of the reflux condenser 200 was controlled at 75 °C. During the reaction, samples were taken for analysis every hour through the bottom sampling tube 140. After 8 hours of reaction, a total of 2.0 mol of DMC (1:1 molar ratio with phenol) was introduced, and then the feed was stopped. Sampling analysis showed that the phenol conversion rate was 95.2% and the selectivity for diphenyl carbonate (DPC) was 98.5%.

[0104] Example 8:

[0105] In a 500 mL high-temperature reactor 100, 188 g (2.0 mol) of phenol and 0.94 g (0.5% of the phenol mass) of iron-bismuth-vanadium oxide composite catalyst were added. The operating procedures were the same as in Example 7, with the reaction temperature set at 180 °C, the DMC feed rate adjusted to 0.05 mol / h (ratio 0.025 mol / mol / h), and the condensation temperature at 80 °C. After 20 hours of reaction, a cumulative 1.0 mol of DMC (molar ratio to phenol 0.5:1) was introduced, and the reaction was stopped. Sampling analysis showed a phenol conversion rate of 85.3% and a DPC selectivity of 97.8%.

[0106] Example 9:

[0107] In a 500 mL high-temperature reactor 100, 188 g (2.0 mol) of phenol and 5.64 g (3.0% of the phenol mass) of nickel-aluminum-vanadium oxide composite catalyst were added. The operating procedures were the same as in Example 7, but the reaction temperature was set to 120 °C. The raw material was replaced with diethyl carbonate (DEC), the feed rate was 0.1 mol / h, and the temperature of the reflux condenser 200 was controlled at 95 °C. After reacting for 10 hours, a total of 1.0 mol of DEC (molar ratio to phenol 0.5:1) was introduced, and the reaction was stopped. Sampling analysis showed that the phenol conversion rate was 88.7%, and the DPC selectivity was 96.9%.

[0108] Example 10:

[0109] In a 500 mL high-temperature reactor 100, 188 g (2.0 mol) of phenol and 2.82 g (1.5% of the phenol mass) of bismuth zinc vanadium oxide composite catalyst were added. The operating procedure was the same as in Example 7, but the reaction temperature was set to 160 °C. The raw material was replaced with diethyl carbonate (DEC), the feed rate was 0.1 mol / h, and the temperature of the reflux condenser 200 was controlled at 95 °C. After reacting for 15 hours, a total of 1.5 mol of DEC (molar ratio to phenol 0.75) was introduced, and the reaction was stopped. Sampling analysis showed that the phenol conversion rate was 93.7% and the DPC selectivity was 96.9%.

[0110] Example 11:

[0111] In a 500 mL high-temperature reactor 100, 188 g (2.0 mol) of phenol and 2 g (1.1% of the phenol mass) of iron-zinc-nickel-vanadium oxide composite catalyst were added. The operating procedure was the same as in Example 7, the reaction temperature was set to 160 °C, and the DMC feed rate was adjusted to 0.1 mol / h (0.05 h). -1 The condensation temperature was 80℃. After 20 hours of reaction, a total of 2.0 mol of DMC (1:1 molar ratio with phenol) was introduced, and the reaction was stopped. Sampling analysis showed that the phenol conversion rate was 96.5% and the DPC selectivity was 98.5%.

[0112] Comparative Example 1 (Traditional Intermittent Method):

[0113] In a conventional high-temperature reactor (without a bottom gas distributor 300 and a top reflux condenser 200), 188 g of phenol, 180 g of DMC (2.0 mol), and 2 g of iron-zinc-nickel-vanadium oxide composite catalyst were added. Feeding was discontinuous, and no N2 carrier gas was introduced. The reaction was carried out at 160°C and 300 rpm for 20 hours with stirring. During the reaction, the byproduct methanol could not be effectively removed. Analysis after the reaction showed a phenol conversion rate of 58.4% and a DMC selectivity of 92.1%.

[0114] Comparative Example 2 (reactor without bottom gas distributor):

[0115] Diphenyl carbonate was synthesized using a reactor without a bottom gas distributor, as designed in patent CN207371131 U. 188 g of phenol, 180 g (2.0 mol) of DMC, and 2 g of an iron-zinc-nickel-vanadium oxide composite catalyst were added. The reaction was carried out at 160 °C and 300 rpm for 20 hours with stirring. Analysis after the reaction showed that the phenol conversion rate was 88.6% and the DMC selectivity was 82.5%.

[0116] Comparative Example 3 (Single Metal Vanadium Oxide):

[0117] In a 500 mL high-temperature reactor 100, 188 g (2.0 mol) of phenol and 3.76 g (2.0% of the phenol mass) of iron-vanadium oxide catalyst were added. The operating procedure was the same as in Example 7. Sampling and analysis showed that the phenol conversion rate was 45.5% and the DPC selectivity was 98.7%.

[0118] Comparative conclusion: The efficient method for synthesizing diphenyl carbonate provided by this invention, namely the continuous feed vaporization transesterification method, significantly improves the phenol conversion rate and DPC selectivity under the same catalyst and reaction time, proving that this invention has outstanding effects in breaking the reaction equilibrium and improving the reaction efficiency.

[0119] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. A method for efficiently synthesizing diphenyl carbonate, characterized in that, This method uses phenol and carbonate as raw materials and a multi-metal vanadium oxide complex as a catalyst to react in a high-temperature reactor equipped with a mechanical stirrer, a reflux condenser and a bottom gas distributor. Carbonate is continuously injected from the bottom of the high-temperature reactor with inert carrier gas. Unreacted carbonate is refluxed through staged condensation, and the by-product alcohol is discharged with the inert carrier gas. The carbonate is dimethyl carbonate or diethyl carbonate; The amount of catalyst used is 0.5~5 wt% of the phenol raw material.

2. The method for efficiently synthesizing diphenyl carbonate according to claim 1, characterized in that, The specific steps of the method for efficiently synthesizing diphenyl carbonate are as follows: S1: Feeding and Replacement: Phenol and catalyst are added to the high-temperature reactor beforehand, the inert carrier gas valve is opened, and inert carrier gas is introduced from the gas distributor to replace the gas in the high-temperature reactor and remove the air. S2: Heating: Under an inert carrier gas atmosphere, start stirring and heat the high-temperature reactor to 120~180℃; S3: Continuous feeding and reaction: Liquid carbonate is pumped in by a metering pump, merged with inert carrier gas from the bottom, and continuously injected into the bottom of the liquid layer of the high-temperature reactor in a bubbling form through a gas distributor. S4: Product removal and reflux: The carbonate gas-liquid mixture injected into the bottom of the liquid layer of the high-temperature reactor is rapidly heated and vaporized under stirring; During the ascent, carbonate vapor and phenol liquid come into full contact on the catalyst surface and undergo transesterification; the generated byproduct alcohol and unreacted carbonate vapor enter the condenser reflux unit along with the inert carrier gas. S5: Condensation separation: Selective separation and reflux of products are achieved by controlling the condensation temperature of the condensation reflux device; carbonate vapor is condensed and refluxed to the high-temperature reactor to continue the reaction, and the by-product alcohol enters the subsequent collection device with the inert carrier gas; S6: Reaction Termination: When the phenol conversion rate reaches the predetermined requirement, stop feeding and end the reaction.

3. The method for efficiently synthesizing diphenyl carbonate according to claim 2, characterized in that, In step S3, the molar ratio of the carbonate injection rate to the initial amount of phenol in the high-temperature reactor is controlled at 0.025~0.125 mol / mol / h, and the ratio of the inert carrier gas flow rate to the initial amount of phenol in the reactor is controlled at 300~2000 mL / mol / h.

4. The method for efficiently synthesizing diphenyl carbonate according to claim 2, characterized in that, In step S3, carbonate is continuously fed for 4 to 20 hours, and the cumulative molar ratio of carbonate to initial phenol is greater than 0.5:

1.

5. The method for efficiently synthesizing diphenyl carbonate according to claim 2, characterized in that, In step S5, the condensation temperature is 70~80℃ when the raw material is dimethyl carbonate and 90~100℃ when the raw material is diethyl carbonate.

6. The method for efficiently synthesizing diphenyl carbonate according to any one of claims 1 to 5, characterized in that, The polymetallic vanadium oxide complex is MVO x M contains at least two metallic elements selected from Fe, Bi, Al, Zn, Ni, and Zr. The multimetallic vanadium oxide complex was prepared by a hydrothermal method, and the specific preparation process is as follows: 1) Raw material preparation: Ammonium vanadate is used as the vanadium source to prepare an ammonium vanadate solution; a mixture of nitrates is used as the metal source to prepare a metal salt solution; 2) Mixing and adjustment: Add the metal salt solution dropwise to the ammonium vanadate solution, stir evenly, and then adjust the pH of the mixture to the range of 2-7 using NaOH solution; 3) Hydrothermal reaction: The pH-adjusted mixture is placed in a hydrothermal environment, and the hydrothermal temperature is controlled at 160~200℃ for a reaction time of 6~24h; 4) Post-processing: The product after hydrothermal reaction is centrifuged, washed with water, dried at 80~100℃ for 6~12h, and then calcined at 200~300℃ for 2~4h to obtain the polymetallic vanadium oxide composite.

7. The method for efficiently synthesizing diphenyl carbonate according to claim 6, characterized in that, The concentration of the metal salt solution is 0.1~0.5 mol / L; The molar ratio of total metal ions to vanadium in the nitrate mixture is 0.5~1.3:

1.

8. The method for efficiently synthesizing diphenyl carbonate according to claim 6, characterized in that, The metal salt solution is added to the ammonium vanadate solution at a dropping rate of 1~5 mL / min, the stirring rate is 300~500 r / min, and the stirring time is 30~60 min.

9. A system for the efficient synthesis of diphenyl carbonate, characterized in that, It includes a high-temperature reactor, a condenser reflux device, and a gas distributor; the condenser reflux device is located at the top of the high-temperature reactor, and the gas distributor is located at the bottom inside the high-temperature reactor. The high-temperature reactor is equipped with an air inlet pipe and a feed pipe at its bottom. The air inlet pipe is connected to the gas distributor. The feed pipe and the air inlet pipe merge before entering the gas distributor.

10. The system for efficiently synthesizing diphenyl carbonate according to claim 9, characterized in that, The high-temperature reactor is equipped with a jacketed heating device on the outside and a mechanical stirring device inside. The high-temperature reactor is also equipped with a bottom sampling tube; The system for the efficient synthesis of diphenyl carbonate further includes a secondary condenser and a secondary condensation collection device. The secondary condenser is connected to the condensation reflux device, and the secondary condensation collection device is connected to the secondary condenser.

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