A process for the simultaneous production of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogention of furfural

Abstract

The application discloses a method for preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by simultaneously hydrogenating furfural. The basic equipment is composed of a reaction rectifying tower, a desolventizing tower, a heavy-removing tower, a phase separator, a compressor and corresponding condensers, reboilers and the like, a Cu-Pd / HY supported catalyst is adopted, and 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol products can be obtained by one-step continuous hydrogenation. In the process, the rectification process can fully utilize the reaction heat of the hydrogenation of furfural as the heat source for vaporizing the material at the lower part of the tower, effectively reduces the heat source consumption of the tower reboiler, and simultaneously reduces the equipment investment of the production device. Through the reaction rectification system, the reaction product can be timely removed from the system, effectively avoids the occurrence of a side reaction, simultaneously improves the reaction conversion rate and the product yield. The process flow of the application is simple, the comprehensive yield of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol is high, the energy consumption is low, and the application has a good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bio-based chemicals refining, in particular to a method for preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, which is a process for producing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol simultaneously by reaction distillation. BACKGROUND

[0002] 2-methyltetrahydrofuran is a product obtained by hydrogenation of furfural, 2-methylfuran and furfuryl alcohol derived from biomass, and the carbon source is entirely from renewable biomass. 2-methyltetrahydrofuran is an important chemical intermediate and chemical raw material, and is widely used as a solvent in the fields of polymer materials and organic chemical production. 2-methyltetrahydrofuran is a new type of gasoline additive, which can be miscible with gasoline at any ratio, and the addition ratio in gasoline can be more than 60% without affecting the performance of the engine; 2-methyltetrahydrofuran is widely used as a new type of green solvent in organic metal reactions, and can be used as a solvent for Grignard reaction, Reformatsky reaction, two-phase reaction, coupling reaction and lithiation reaction; 2-methyltetrahydrofuran also has important applications in batch production of fine chemicals, enzymatic polycondensation and ring-opening polymerization, and can be used to synthesize drugs such as primaquine for treating cancer, and has a broad development and utilization prospect.

[0003] Tetrahydrofurfuryl alcohol, also known as tetrahydrofuran-2-methanol, is widely used and is an important organic synthesis intermediate for the synthesis of succinic acid, glutaric acid, tetrahydrofuran, lysine, long-acting vitamins, furan and pyridine, and is a good soldering solvent in electronic chemicals and soldering fluxes. In addition, tetrahydrofurfuryl alcohol can also be used as a plasticizer to prepare polyamide plastics, and is also an excellent plasticizer, decolorizing agent and deodorizing agent.

[0004] 2-methyltetrahydrofuran is currently mainly prepared by a hydrogenation process, and a fixed bed reactor or a kettle type reactor is usually selected. The main process preparation method is as follows:

[0005] Patent CN103214437A realizes continuous production of 2-methyltetrahydrofuran by using a fixed bed reactor. Under the condition of a nickel-based catalyst, gaseous 2-methylfuran reacts with hydrogen under the action of the catalyst, and 2-methyltetrahydrofuran is obtained after condensation. The reaction conditions of the fixed bed reactor are 90-200℃, 0-1.0MPaA, the conversion rate of furfural is >99%, and the selectivity of 2-methyltetrahydrofuran is 73%-93%.

[0006] Patent CN105601592A adopts two kinds of metal catalysts segmented packing method, Cu-based catalyst and Pb catalyst are fixed respectively in the upstream and downstream of the fixed bed reactor, so that furfural is generated 2-methyl tetrahydrofuran by one step hydrogenation, the reaction condition is: 180-182℃, normal pressure (0.1 MPa), 2-methyl tetrahydrofuran selectivity is 97.1%.

[0007] Patent CN106905269A provides a kettle type continuous hydrogenation process for producing 2-methyl tetrahydrofuran, after two-step hydrogenation of the raw material 2-methyl furan through the main reaction kettle and the auxiliary reaction kettle in series, the product is obtained by rectification after gas-liquid separation. The reaction condition is: 50-90℃, 5-6 MPaA, the yield of 2-methyl tetrahydrofuran after rectification is 98.2%.

[0008] Patent CN11419572A adds 2-methyl furan into a loop reactor to prepare 2-methyl tetrahydrofuran, wherein the loop reactor comprises a reaction kettle, a circulating pump, a heat exchanger, a venturi injector and the like. The reaction condition is: 40-100℃, 2-4 MPaA, 2-methyl furan conversion rate > 99%, 2-methyl tetrahydrofuran selectivity is 73%-93%.

[0009] Patent CN115228387A discloses a continuous preparation system of 2-methyl tetrahydrofuran, which realizes effective isolation of the catalyst and full mixing of the solvent by setting a bottom plate in the reaction kettle and setting a circulating pump on the side surface of the reaction kettle.

[0010] Tetrahydrofurfuryl alcohol is prepared by furfural or furfuryl alcohol hydrogenation process, also using fixed bed reactor or kettle type reactor, the main process preparation method is as follows:

[0011] Patent CN104672185A adopts liquid phase kettle type hydrogenation method, furfural is generated tetrahydrofurfuryl alcohol by one step under the action of nickel-based catalyst and alkaline additive, the reaction condition is: 80-180℃, 0.5-10 MPa, tetrahydrofurfuryl alcohol selectivity can reach 94%;

[0012] Patent CN110240578A adopts fixed bed reactor, supported nickel catalyst for liquid phase hydrogenation of furfural to prepare tetrahydrofurfuryl alcohol by one step, the reaction condition is: 60-120℃, 0.5-8 MPa.

[0013] Patent CN113549034A adopts two-stage full-mixing series kettle type reactor, and is prepared by eggshell type nickel-based alloy catalyst, high-purity tetrahydrofurfuryl alcohol is obtained after desolventizing tower and rectifying tower, the reaction condition is: 20-80℃, 2.0-4.0 MPa.

[0014] Patent CN106622219A uses a supported ruthenium catalyst to prepare tetrahydrofurfuryl alcohol in a liquid phase hydrogenation reaction in a reaction kettle, and the reaction conditions are: 30-80 DEG C, 1.5-2 MPa;

[0015] From the currently disclosed preparation methods of 2-methyltetrahydrofuran, the raw materials are all biomass derived from biomass, the biomass is prepared into furfural, and then 2-methyltetrahydrofuran is prepared by one-step method (furfural directly preparing 2-methyltetrahydrofuran) or two-step method (furfural preparing 2-methylfuran, and then 2-methylfuran is continuously hydrogenated to obtain 2-methyltetrahydrofuran). The preparation method of tetrahydrofurfuryl alcohol is similar to that of 2-methyltetrahydrofuran, and the hydrogenation raw material is mainly furfural or furfuryl alcohol. For the existing process method, one-step hydrogenation reaction cannot obtain 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol with high selectivity. Since furfural, furfuryl alcohol, 2-methylfuran, 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol belong to the same industrial chain, obtaining two products with high selectivity through one process can better meet market demand, reduce plant investment, and have better economic benefits.

[0016] At present, the reactor forms of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol production devices used in the industry mainly include fixed bed reactors and kettle type reactors, and the qualified products are obtained by distillation separation after reaction, which has high energy consumption and large equipment investment. In view of the above problems, reaction distillation is a better solution. The reaction heat of furfural hydrogenation can be fully utilized as the heat source for vaporization of the material at the lower part of the tower, which effectively reduces the heat source consumption of the tower kettle reboiler and also reduces the equipment investment of the production device.

[0017] The catalytic reaction distillation for preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol developed by the application can remove the reaction products (2-methyltetrahydrofuran, tetrahydrofurfuryl alcohol and water) from the system in time, effectively avoid the occurrence of side reactions, and improve the reaction conversion rate and product yield. At the same time, the continuous production process can also guarantee the product quality. The method uses a Cu-Pd / HY supported catalyst, which has good activity. SUMMARY

[0018] The purpose of the application is to provide a reaction distillation system and method for producing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by one-step hydrogenation of furfural. The reaction principle equation is as follows:

[0019]

[0020] In order to achieve the above-mentioned purpose of the application, the application provides the following technical solutions:

[0021] (1) Furfural and solvent n-heptane are pumped into a mixer, and then mixed and input into the feed total pipeline of the reaction distillation tower. Fresh hydrogen and recycled hydrogen are transported to the gas inlet of the reaction distillation tower by a compressor.

[0022] (2) The mixture of furfural and n-heptane is delivered from the feed total pipe to the top of the reaction section of the reaction rectifying tower, and hydrogen is delivered to the gas inlet of the bottom of the reaction section of the reaction rectifying tower. The furfural and hydrogen are subjected to one-step continuous hydrogenation reaction in the reaction section of the reaction rectifying tower to generate 2-methyltetrahydrofuran, tetrahydrofurfuryl alcohol and a small amount of heavy component impurities (mainly ester substances generated by rearrangement of hydrogenation of furfuryl alcohol). The reaction section of the reaction rectifying tower uses Cu-Pd / HY supported bimetallic catalyst, the weight percentage content of Cu is 8wt% to 15wt% and the weight percentage content of Pd is 0.5wt% to 12wt% based on the total weight. The reaction product is separated by the rectifying section and the stripping section, 2-methyltetrahydrofuran, water and hydrogen are collected from the top of the tower, and n-heptane, tetrahydrofurfuryl alcohol and a small amount of heavy component impurities are collected from the bottom of the tower. The reaction rectifying tower is a packed tower, preferably including regular packing and random packing, and the material is preferably ordinary stainless steel; the operating pressure of the reaction rectifying tower is 1.8 to 2.5 MPa (for example, 1.8 MPa, 1.85 MPa, 1.9 MPa, 1.95 MPa, 2 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, 2.4 MPa or 2.5 MPa), the operating temperature is 150 to 340°C (for example, 150°C, 7°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C or 340°C), the number of theoretical plates is 30 to 80 (for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80), and the reflux ratio is 2 to 5 (for example, 2, 2.5, 3, 3.5, 4, 4.5 or 5).

[0023] (3) The product at the top of the reaction rectifying tower is cooled to -5 to 5°C (for example, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C or 5°C) by a deep cooling device and then delivered to a phase separator for three-phase separation, the phase separator is under pressure of 1.8 to 2.4 MPa (for example, 1.8 MPa, 1.85 MPa, 1.9 MPa, 1.95 MPa, 2 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa or 2.4 MPa), and the oil phase is collected by static separation to obtain a mixture of 2-methyltetrahydrofuran and n-heptane, which is pumped to a desolventizing tower. The non-condensable gas at the top of the phase separator is mainly hydrogen, which is compressed by a compressor and then reused.

[0024] (4) The oil phase of the phase separator is continuously sent to the desolventizing tower through a pump, and the solvent n-heptane obtained in the tower bottom is directly mixed with furfural and then returned to the reactive distillation tower. The top of the tower is 2-methyltetrahydrofuran product, which is pumped to the 2-methyltetrahydrofuran storage tank by a pump. The desolventizing tower is a structured packing or random packing distillation tower, and the tower body and packing are preferably made of stainless steel (SS304 or SS316); the number of theoretical plates of the desolventizing tower is 30 to 60 (for example, 30, 35, 40, 45, 50, 55 or 60); the operating conditions of the desolventizing tower are: 0.04 to 0.09 MPa (for example, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa or 0.09 MPa), 70-96°C (tower top) (e.g., 70°C, 72°C, 75°C, 80°C, 85°C, 90°C, 95°C or 96°C), 107-158°C (tower bottom) (e.g., 107°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C or 158°C), and a reflux ratio of 1-4 (e.g., 1, 2, 3 or 4).

[0025] (5) The product from the bottom of the reaction distillation tower is continuously sent to the deweighting tower by a pump, and tetrahydrofurfuryl alcohol (tetrahydrofurfuryl alcohol content ≥ 99%) is obtained at the top of the deweighting tower, and the bottom of the tower is the heavy component impurities. The deweighting tower is a structured packing or random packing distillation tower, and the tower body and packing are preferably made of stainless steel (SS304 or SS316); the number of theoretical plates of the desolventizing tower is 28 to 60 (for example, 28, 30, 35, 40, 45, 50, 55 or 60); the operating conditions of the deweighting tower are: 0.06 to 0.12 MPa (for example, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa or 0.12 MPa), 152 to 19 5°C (tower top) (for example, 152°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C or 195°C), 198-254°C (tower bottom) (for example, 198°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C or 254°C), and a reflux ratio of 2-5 (for example, 2, 2.5, 3, 3.5, 4, 4.5 or 5).

[0026] Furthermore, the reactive distillation tower is a packed tower, and the packing is corrugated stainless steel plate 125Y, 250Y or 350Y.

[0027] Furthermore, the deweighting tower is a packed distillation tower, and the packing is corrugated stainless steel plate 125Y, 250Y or 350Y, and the packing can also be stainless steel wire mesh AX250, BX500 or CY700.

[0028] Further, the desolventizing column is a packed distillation column, and the packing is stainless steel sheet corrugation 125Y, 250Y or 350Y. The packing can also be stainless steel wire mesh AX250, BX500 or CY700.

[0029] Further, the furfural and the solvent n-heptane are mixed in a ratio of 1:0.2-4 (for example, 1:0.2, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4) and then input into the feed total pipeline of the reaction distillation column.

[0030] Further, the reaction distillation column in step (2) is continuously operated, the overhead temperature is 150-180°C (for example, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C), the reaction section temperature is 210-250°C (for example, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C or 250°C), and the bottom temperature is 250-310°C (for example, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C or 310°C).

[0031] Further, the reaction distillation column in step (2) is provided with a packing layer (structured packing) and a catalyst layer from top to bottom, the height of each layer of the catalyst layer is 1.5-4 m (for example, 1.5 m, 2 m, 2.5 m, 3 m, 3.5 m or 4 m), the number of catalyst layers is 1-3 layers (for example, 1 layer, 2 layers or 3 layers). A distributor is arranged above each section, and the distributor is connected to the total pipeline of the reaction distillation column.

[0032] Preferably, the reaction distillation column in step (2) uses a Cu-Pd supported bimetallic catalyst, the weight percentage of Cu is 10% and the weight percentage of Pd is 5wt% based on the total weight.

[0033] Further, the Cu-Pd / HY supported catalyst is used in the reaction process in step (2), and the catalyst preparation steps are as follows:

[0034] (1) Pd salt, deionized water, molecular sieve and copper salt are stirred and mixed at normal temperature and pressure for 5-24 hours to obtain a mixed solution. (2) The obtained mixed solution is dried at 80-150°C under air atmosphere and normal pressure for 8-20 hours. (3) The dried catalyst is calcined at 400-600°C (for example, 400°C, 425°C, 450°C, 475°C, 500°C, 525°C, 550°C, 575°C or 600°C) under air atmosphere and normal pressure for 4-16 hours to obtain a Cu-Pd supported bimetallic catalyst. The Cu content is 8wt%-15wt% and the Pd content is 0.5wt%-12wt% based on the total mass of the Cu-Pd supported bimetallic catalyst.

[0035] For example, the Cu content is 8wt%, 8.2wt%, 8.5wt%, 8.7wt%, 9wt%, 9.2wt%, 9.5wt%, 9.7wt%, 10.1wt%, 10.2wt%, 10.3wt%, 10.4wt%, 10.5wt%, 10.6wt%, 10.7wt%, 10.8wt%, 10.9wt%, 11wt%, 11.5wt%, 12wt%, 12.5wt%, 13wt%, 13.5wt%, 14wt%, 14.5wt% or 15wt% based on the total mass of the Cu-Pd supported bimetallic catalyst.

[0036] For example, the Pd content is 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4.2wt%, 4.4wt%, 4.6wt%, 4.8wt%, 5wt%, 5.2wt%, 5.5wt%, 5.7wt%, 6wt%, 6.2wt%, 6.5wt%, 6.7wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, 11.5wt% or 12wt% based on the total mass of the Cu-Pd supported bimetallic catalyst.

[0037] The Cu-Pd / HY catalyst needs to be reduced by hydrogen before use; preferably, the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas, the temperature is raised to 450-550°C (for example, 450°C, 475°C, 500°C, 525°C or 550°C) at a temperature rise rate of 3-6°C / min (for example, 3°C / min, 4°C / min, 5°C / min or 6°C / min), and then the temperature is kept constant for 1-6 hours for reduction, the hydrogen / nitrogen mixed gas flow rate is 0.001-0.002 Nm 3 / h. For example, the reducing gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, which is heated to 500℃ at a heating rate of 5℃ / min, and then reduced for 3 hours, the flow rate of the hydrogen / nitrogen mixed gas is 0.002Nm 3 / h.

[0038] Preferably, the total theoretical plate number of the reaction rectification in step (2) is 30-80, wherein the theoretical plate number of the reaction section is 10-30, and the theoretical plate number of the rectification section is 20-50. Furfural is fed from above the reaction section, and hydrogen is fed below the reaction section.

[0039] Preferably, the overhead product of the reaction rectification column in step (3) is cooled to -5℃ by a deep cooler.

[0040] Preferably, the non-condensable gas discharged from the phase separator in step (3) is hydrogen, which is pressurized by a hydrogen compressor and then returned to the reaction rectification column for recycling.

[0041] Preferably, the desolventizing process in step (5) uses a structured packing column for the desolventizing column, the theoretical plate number of the desolventizing column is 35-50, and the operating reflux ratio of the desolventizing column is 2-3.

[0042] Preferably, the heavy component removal process in step (6) uses a structured packing column for the heavy component removal column, the theoretical plate number of the heavy component removal column is 30-40, and the operating reflux ratio of the desolventizing column is 1.5-3.

[0043] Advantages and beneficial effects of the present application:

[0044] 1. The present application simultaneously obtains two products with high selectivity by using the same set of process devices; the present method uses a Cu-Pd / HY supported catalyst, which has good activity and can obtain two products with different yields by quickly adjusting the content of the active metal component of the catalyst according to market demand, thereby effectively reducing the investment in building a plant and achieving better economic benefits.

[0045] 2. Currently, the reactors used in the production devices of 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol in the industry are mainly fixed bed reactors and kettle reactors, and the qualified products are obtained by distillation separation after reaction, which has high energy consumption and large equipment investment. The present application uses continuous reaction rectification, and the distillation process can fully utilize the reaction heat of furfural hydrogenation as the heat source for vaporization of the material in the lower part of the column, thereby effectively reducing the heat source consumption of the column bottom reboiler and also reducing the equipment investment of the production device.

[0046] 3. The catalytic reactive distillation method developed by the present invention for preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol allows the reaction products (2-methyltetrahydrofuran, tetrahydrofurfuryl alcohol, and water) to be promptly removed from the system through the reactive distillation system, effectively preventing side reactions while improving reaction conversion and product yield. Furthermore, the continuous production process ensures product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention is a process flow chart for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenating furfural.

[0048] In the figure: 1-mixer; 2-reaction distillation tower; 3-condenser of reaction distillation tower; 4-reflux tank of reaction distillation tower; 5-weight removal tower; 6-condenser of weight removal tower; 7-reflux tank of weight removal tower; 8-cold freezer of reaction distillation tower; 9-phase separator; 10-desolventizing tower; 11-condenser of desolventizing tower; 12-reflux tank of desolventizing tower; 13-reboiler of reaction distillation tower; 14-reboiler of weight removal tower; 15-reboiler of desolventizing tower; 16-compressor. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the following embodiments: The following embodiments are illustrative rather than restrictive, and the scope of protection of the present invention cannot be limited by the following embodiments.

[0050] like Figure 1 As shown. A device for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenating furfural, wherein a mixer 1 is provided with a furfural inlet and a solvent inlet. For example, there are two solvent inlets. The outlet of the mixer 1 is connected to a feed main pipe, which is divided into two routes, one route connected to a first feed port in the middle of a reaction distillation tower 2, and the other route connected to a second feed port in the middle of the reaction distillation tower 2. A hydrogen feed port and a reaction distillation tower reboiler 13 are provided at the lower portion of the reaction distillation tower 2. The top outlet of the reaction distillation tower 2 is connected in sequence to a reaction distillation tower condenser 3 and a reaction distillation tower reflux tank 4. The outlet of the reaction distillation tower reflux tank 4 is divided into two routes, one route returning to the upper portion of the reaction distillation tower 2, and the other route connected in sequence to a reaction distillation tower cryogenic cooler 8 and a phase separator 9; the top outlet of the phase separator 9 is connected to the inlet of a compressor 16, and the outlet of the compressor 16 is connected to the hydrogen feed port at the lower portion of the reaction distillation tower 2; the bottom of the phase separator 9 is provided with a wastewater outlet and a bottom outlet of the phase separator 9. The bottom outlet of the reactive distillation column 2 is connected to the middle feed port of the de-weighting column 5. The top outlet of the de-weighting column 5 is connected in sequence to the de-weighting column condenser 6 and the de-weighting column reflux tank 7. The outlet of the de-weighting column reflux tank 7 is divided into two paths, one returning to the top of the de-weighting column 5 and the other being the outlet for the tetrahydrofurfuryl alcohol product. The lower part of the de-weighting column 5 is provided with a de-weighting column reboiler 14. The bottom outlet of the de-weighting column 5 is an outlet for heavy component impurities.

[0051] The bottom outlet of the phase separator 9 is connected to the middle inlet of the desolventizing column 10; the top outlet of the desolventizing column 10 is connected to the desolventizing column condenser 11 and the desolventizing column reflux tank 12 in sequence. The outlet of the desolventizing column reflux tank 12 is divided into two routes, one of which returns to the upper part of the desolventizing column 10, and the other is the 2-methyl tetrahydrofuran product outlet; the bottom of the desolventizing column 10 is provided with a desolventizing column reboiler 15.

[0052] The reaction rectification column is provided with a packing layer (regular packing) and a catalyst layer from top to bottom, the height of each layer of the catalyst layer is 1.5-4 m, and the number of catalyst layers is 1-3. A distributor is arranged above each section, and the distributor is connected with the feed total pipeline of the reaction rectification column.

[0053] A method for preparing 2-methyl tetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural simultaneously, using the device for preparing 2-methyl tetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural simultaneously, the method comprises the following steps:

[0054] (1) Furfural and solvent n-heptane are pumped into a mixer 1, and then input into the feed total pipeline of the reaction rectification column 2 after mixing. Fresh hydrogen and recycled hydrogen are transported to the gas inlet of the reaction rectification column by a compressor.

[0055] (2) The mixed solution of furfural and n-heptane is transported to the top of the reaction section of the reaction rectification column by the feed total pipeline, and hydrogen is transported to the gas inlet at the bottom of the reaction section of the reaction rectification column. Furfural and hydrogen are subjected to one-step continuous hydrogenation reaction in the reaction section of the reaction rectification column to generate 2-methyl tetrahydrofuran, tetrahydrofurfuryl alcohol and a small amount of heavy component impurities (mainly ester substances generated by hydrogenation rearrangement of furfuryl alcohol). The reaction section of the reaction rectification column adopts a Cu-Pd / HY supported bimetallic catalyst, the weight percentage content of Cu is 8wt%-15wt% and the weight percentage content of Pd is 0.5wt%-12wt% based on the total weight. After separation by the rectification section and the stripping section, 2-methyl tetrahydrofuran, water and hydrogen are collected from the top of the column, n-heptane, tetrahydrofurfuryl alcohol and a small amount of heavy component impurities are collected from the column bottom. The reaction rectification column is a packed column, including regular packing and random packing, and the material is ordinary stainless steel; the operation pressure of the reaction rectification column 2 is 1.8-2.5 MPa, the operation temperature is 150-340℃, the number of theoretical plates is 30-80, and the reflux ratio is 2-5.

[0056] (3) The top product of the reaction rectification column is cooled to-5-5℃ by a deep cooler and then transported to a phase separator 9 for three-phase separation, the phase separator is under pressure, the pressure is 1.8-2.4 MPa, and the oil phase, the water phase and the gas phase are separated by static separation; the oil phase is collected to obtain a mixture of 2-methyl tetrahydrofuran and n-heptane, and the mixture is pumped to the desolventizing column 10. The gas phase is non-condensable gas at the top of the phase separator. The non-condensable gas at the top of the phase separator is mainly hydrogen, which is recycled after compression by a compressor. The water phase is waste water, which is discharged to a sewage treatment pipeline.

[0057] (4) The oil phase of the phase separator is continuously pumped to the desolventizing tower 10. The solvent n-heptane obtained in the tower bottom is directly mixed with furfural and then reused in the reactive distillation tower. The top of the tower is the 2-methyltetrahydrofuran product, which is pumped to the 2-methyltetrahydrofuran storage tank. The desolventizing tower is a structured packing or random packing distillation tower. The tower body and packing are made of stainless steel (SS304 or SS316). The number of theoretical plates of the desolventizing tower is 30 to 60. The operating conditions of the desolventizing tower are: 0.04 to 0.09 MPa, 70 to 96°C (tower top), 107 to 158°C (tower bottom), and a reflux ratio of 1 to 4.

[0058] (5) The product from the bottom of the reactive distillation column is continuously pumped to a de-weighting column 5, where tetrahydrofurfuryl alcohol (tetrahydrofurfuryl alcohol content ≥ 99%) is obtained at the top of the de-weighting column, and the bottom of the column contains heavy impurities. The de-weighting column 5 is a structured packing or random packing distillation column, and the tower body and packing are made of stainless steel (SS304 or SS316). The number of theoretical plates of the desolventizing column is 28 to 60. The operating conditions of the de-weighting column are: 0.06 to 0.12 MPa, 152 to 195°C (tower top), 198 to 254°C (tower bottom), and a reflux ratio of 2 to 5.

[0059] In the following embodiments of the present invention, the reactive distillation tower is a packed tower, the packing is made of corrugated plate 125Y, and the packing and tower body are made of stainless steel (SS304); the reactive distillation tower is provided with a packing layer and a catalyst layer from top to bottom, each catalyst layer has a height of 1.5m, and the number of catalyst layers is 3.

[0060] The deweighting tower is a packed distillation tower, the packing is corrugated plate 125Y, and the tower body and packing are made of stainless steel (SS304).

[0061] The desolventizing tower is a packed distillation tower, the packing is plate corrugated 125Y, and the tower body and packing are made of stainless steel (SS304).

[0062] Example 1

[0063] Use as Figure 1 The device is a method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenating furfural, and the steps are as follows:

[0064] In step (1), 1500.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) are pressurized and continuously delivered to the mixer 1 by a delivery pump, the flow mass ratio of furfural to n-heptane is 1:0.5, and the continuous feed rate of hydrogen (purity 99.9 vol%) is 200.0 kg / h.

[0065] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 40, the reactant furfural and n-heptane are fed into the column at the 12th plate and the 21st plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 28th theoretical plate. The 12th-28th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 25.0 kg, and the reflux ratio is 3.0. The top temperature of the reactive distillation column is 169°C, a partial condenser is used, the pressure is controlled at 2.0 MPa, and the top output is 2183.4 kg / h (2-methyltetrahydrofuran content is 51.2 wt%, water content is 10.7 wt%, n-heptane content is 34.4 wt%, and hydrogen content is 3.7 wt%). The bottom temperature is 286°C, the heat is provided by the reaction heat of furfural hydrogenation reaction and the reboiler of the reactive distillation column, and the bottom output is 267.0 kg / h (tetrahydrofurfuryl alcohol content is 68.4 wt%, and heavy component impurity content is 31.6 wt%).

[0066] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0067] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water, and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.53: 1.90: 50: 4.25.

[0068] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0069] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY supported catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 5.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, then the temperature is kept constant for 3 hours of reduction, the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0070] The overhead product of the reactive distillation column in step (3) was cooled to -5°C by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 89.7 kg / h (2-methyltetrahydrofuran content 7.4 wt%, water content 0.4 wt%, n-heptane content 2.4 wt%, hydrogen content 89.8 wt%), the oil phase output was 1861.0 kg / h (2-methyltetrahydrofuran content 59.7 wt%, water content 0.1 wt%, n-heptane content 40.2 wt%), and the waste water discharge was 232.4 kg / h.

[0071] The desolventizing column in step (4) had 36 trays, a reflux ratio of 2, and a pressure of 0.07 MPa. The overhead temperature of the desolventizing column was 86°C, and the 2-methyltetrahydrofuran product output was 1110.7 kg / h (2-methyltetrahydrofuran purity 99.1 wt%). The solvent n-heptane was discharged from the column bottom, the column bottom temperature was 140°C, and the n-heptane output was 750.3 kg / h (n-heptane content 98.6 wt%, 2-methyltetrahydrofuran content 1.4 wt%).

[0072] The heavy component removal column in step (5) had 32 trays, a reflux ratio of 4, and a pressure of 0.1 MPa. The overhead temperature of the heavy component removal column was 177°C, and the tetrahydrofurfuryl alcohol product output was 182.0 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities were discharged from the column bottom, the column bottom temperature was 211°C, and the heavy component output was 85.0 kg / h (heavy component content 99.3 wt%, tetrahydrofurfuryl alcohol content 0.7 wt%).

[0073] Under these conditions, the qualified products were obtained, the 2-methyltetrahydrofuran yield was 82.6%, and the tetrahydrofurfuryl alcohol yield was 11.4%.

[0074] Example 2

[0075] Using the device as described in Figure 1 A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, the steps are as follows:

[0076] In step (1), 1500.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) were continuously fed into a mixer by a pump, the mass ratio of furfural to n-heptane was 1:0.5, and the continuous feeding amount of hydrogen (purity 99.9 vol%) was 200.0 kg / h.

[0077] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 40, the reactant furfural and n-heptane are fed into the column at the 12th plate and the 21st plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 28th theoretical plate. The 12th-28th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 25 kg, and the reflux ratio is 3.0. The top temperature of the reactive distillation column is 158°C, a partial condenser is used, the pressure is controlled at 2.0 MPa, and the top output is 1798.8 kg / h (2-methyltetrahydrofuran content 40.0 wt%, water content 15.1 wt%, n-heptane content 41.8 wt%, and hydrogen content 3.1 wt%). The bottom temperature is 305°C, the heat is provided by the reaction heat of furfural hydrogenation and the reboiler, and the bottom output is 652.5 kg / h (tetrahydrofurfuryl alcohol content 69.2 wt%, and heavy component impurity content 30.8 wt%).

[0078] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0079] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water, and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of the raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.76: 1.95: 50: 4.25.

[0080] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0081] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 7.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, then the temperature is kept constant for 3 hours of reduction, the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0082] The overhead product of the reactive distillation column in step (3) was cooled to -5°C by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 56.3 kg / h (2-methyltetrahydrofuran content 7.0 wt%, water content 0.4 wt%, n-heptane content 2.7 wt%, hydrogen content 89.9 wt%), the oil phase output was 1466.7 kg / h (2-methyltetrahydrofuran content 51.2 wt%, water content 0.1 wt%, n-heptane content 48.7 wt%), and the waste water discharge was 275.8 kg / h.

[0083] The desolventizing column in step (4) had 36 trays, a reflux ratio of 2, and a pressure of 0.07 MPa. The overhead temperature of the desolventizing column was 86°C, and the 2-methyltetrahydrofuran product output was 715.4 kg / h (2-methyltetrahydrofuran purity 99.0 wt%). The solvent n-heptane was taken from the column bottom, the column bottom temperature was 143°C, and the n-heptane output was 751.3 kg / h (n-heptane content 98.9 wt%, 2-methyltetrahydrofuran content 1.1 wt%).

[0084] The heavy component column in step (5) had 32 trays, a reflux ratio of 4, and a pressure of 0.1 MPa. The overhead temperature of the desolventizing column was 176°C, and the tetrahydrofurfuryl alcohol product output was 451.3 kg / h (tetrahydrofurfuryl alcohol purity 99.3 wt%). The heavy component impurities were taken from the column bottom, the column bottom temperature was 227°C, and the heavy component impurities output was 201.2 kg / h (heavy component content 99.1 wt%, tetrahydrofurfuryl alcohol content 0.9 wt%).

[0085] Under these conditions, the product was obtained, the 2-methyltetrahydrofuran yield was 53.2%, and the tetrahydrofurfuryl alcohol yield was 28.3%.

[0086] Example 3

[0087] Using the device as described in Figure 1 A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, the steps are as follows:

[0088] In step (1), 1500.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) were continuously fed into a mixer by a pump, the mass ratio of furfural to n-heptane was 1:0.5, and the continuous feeding amount of hydrogen (purity 99.9 vol%) was 200.0 kg / h.

[0089] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 40, the reactant furfural and n-heptane are fed into the column at the 12th plate and the 21st plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 28th theoretical plate. The 12th-28th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 25 kg, and the reflux ratio is 3.0. The top temperature of the reactive distillation column is 161°C, a partial condenser is used, the pressure is controlled at 2.0 MPa, and the top output is 1955.9 kg / h (2-methyltetrahydrofuran content 44.7 wt%, water content 15.0 wt%, n-heptane content 38.4 wt%, and hydrogen content 1.9 wt%). The bottom temperature is 311°C, the heat is provided by the reaction heat of furfural hydrogenation and the reboiler, and the bottom output is 494.5 kg / h (tetrahydrofurfuryl alcohol content 27.7 wt%, and heavy component impurity content 72.3 wt%).

[0090] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0091] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water, and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of the raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.31: 1.86: 50: 4.25.

[0092] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0093] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 3.0 wt% based on the mass of the catalyst.

[0094] Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, and then the reduction is carried out for 3 hours, the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0095] The overhead product of the reactive distillation column in step (3) was cooled to -5°C by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 36.3 kg / h (2-methyltetrahydrofuran content 6.0 wt%, water content 0.9 wt%, n-heptane content 2.8 wt%, hydrogen content 90.3 wt%), the oil phase output was 1626.4 kg / h (2-methyltetrahydrofuran content 53.8 wt%, water content 0.1 wt%, n-heptane content 46.1 wt%), and the waste water discharge was 293.2 kg / h.

[0096] The desolventizing column in step (4) had 36 plates and operated at a pressure of 0.06 MPa. The overhead temperature of the desolventizing column was 86°C, and the 2-methyltetrahydrofuran product output was 875.4 kg / h (2-methyltetrahydrofuran purity 99.2 wt%). The solvent n-heptane was withdrawn from the column bottom, and the column bottom temperature was 157°C. The n-heptane output was 751.0 kg / h (n-heptane content 98.8 wt%, 2-methyltetrahydrofuran content 1.2 wt%).

[0097] The heavy component column in step (5) had 32 plates and operated at a pressure of 0.1 MPa and a reflux ratio of 4. The overhead temperature of the heavy component column was 177°C, and the tetrahydrofurfuryl alcohol product output was 137.1 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities were withdrawn from the column bottom, and the column bottom temperature was 211°C. The heavy component output was 357.4 kg / h (heavy component content 98.2 wt%, tetrahydrofurfuryl alcohol content 1.8 wt%).

[0098] Under these conditions, the product was obtained, and the 2-methyltetrahydrofuran yield was 65.1%, and the tetrahydrofurfuryl alcohol yield was 8.6%.

[0099] Example 4

[0100] Using the apparatus as described in Figure 1 A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, the steps are as follows:

[0101] In step (1), 1800.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) were continuously fed to a mixer by a pump, and the mass ratio of furfural to n-heptane was 1:0.5. The continuous hydrogen feed was 320.0 kg / h (purity 99.9 vol%).

[0102] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 45, the reactant furfural and n-heptane are fed into the column at the 10th plate and the 21st plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 30th theoretical plate. The 10th-30th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 32.5 kg, and the reflux ratio is 3.8. The top temperature of the distillation column is 169°C, a partial condenser is used, the pressure is controlled at 2.0 MPa, and the top output is 2637.3 kg / h (2-methyltetrahydrofuran content is 51.1 wt%, water content is 10.6 wt%, n-heptane content is 34.2 wt%, and hydrogen content is 4.1 wt%). The bottom temperature is 281°C, the heat is provided by the reaction heat of furfural hydrogenation reaction and the reboiler, and the bottom output is 324.8 kg / h (tetrahydrofurfuryl alcohol content is 68.3 wt%, and heavy component impurity content is 31.7 wt%).

[0103] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0104] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.53: 1.90: 50: 4.25.

[0105] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0106] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY supported catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 5.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, then the temperature is kept constant for 3 hours of reduction, the flow rate of hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0107] In step (3), the overhead product of the reactive distillation tower is cooled to -5°C through a cryogenic refrigerator, and the operating pressure of the phase separator is 1.9 MPa. The phase separator gas phase output is 107.6 kg / h (2-methyltetrahydrofuran content 7.3 wt%, water content 0.4 wt%, n-heptane content 2.3 wt%, hydrogen content 90.0 wt%), the oil phase output is 2250.8 kg / h (2-methyltetrahydrofuran content 59.9 wt%, water content 0.1 wt%, n-heptane content 40.0 wt%), and the wastewater discharge rate is 278.88 kg / h.

[0108] In step (4), the desolventizing tower used 36 trays, a reflux ratio of 2, and a pressure of 0.07 MPa. The desolventizing tower top temperature was 86° C., and the 2-methyltetrahydrofuran product output was 1349.0 kg / h (2-methyltetrahydrofuran purity 99.1 wt%). The solvent n-heptane was extracted from the desolventizing tower bottom at a bottom temperature of 138° C., with an n-heptane output of 901.8 kg / h (n-heptane content 98.8 wt%, 2-methyltetrahydrofuran content 1.2 wt%).

[0109] In step (5), the degassing column has 32 trays, a reflux ratio of 4, and a pressure of 0.1 MPa. The degassing column top temperature is 176° C., and the tetrahydrofurfuryl alcohol product output is 222.0 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities are extracted from the desolventizing column bottom reactor at a temperature of 208° C., and the heavy component output is 102.8 kg / h (heavy component content 99.3 wt%, tetrahydrofurfuryl alcohol content 0.7 wt%).

[0110] Under these conditions, qualified products were obtained, with a 2-methyltetrahydrofuran yield of 84.2% and a tetrahydrofurfuryl alcohol yield of 11.1%.

[0111] Example 5

[0112] Use as Figure 1 The device is a method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenating furfural, and the steps are as follows:

[0113] In step (1), 1500.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) are pressurized and continuously delivered to the mixer by delivery pumps, the flow mass ratio of furfural to n-heptane is 1:1.5, and the continuous feed rate of hydrogen (purity 99.9 vol%) is 200.0 kg / h.

[0114] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 45, the reactant furfural and n-heptane are fed into the column at the 12th plate and the 21st plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 28th theoretical plate. The 12th-28th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 33.4 kg, and the reflux ratio is 2.1. The top temperature of the distillation column is 168°C, a partial condenser is used, the pressure is controlled at 2.0 MPa, and the top output is 3692.3 kg / h (2-methyltetrahydrofuran content is 51.2 wt%, water content is 10.7 wt%, n-heptane content is 34.4 wt%, and hydrogen content is 3.7 wt%). The bottom temperature is 254°C, the heat is provided by the reaction heat of furfural hydrogenation and the reboiler, and the bottom output is 259.2 kg / h (tetrahydrofurfuryl alcohol content is 71.4 wt%, and heavy component impurity content is 28.6 wt%).

[0115] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0116] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water, and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.53: 1.90: 50: 4.25.

[0117] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0118] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY supported catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 5.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, then the temperature is kept constant for 3 hours of reduction, the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0119] The overhead product of the reactive distillation column in step (3) was cooled to -5°C by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 53.3 kg / h (2-methyltetrahydrofuran content 7.5 wt%, water content 0.3 wt%, n-heptane content 2.6 wt%, hydrogen content 89.6 wt%), the oil phase output was 3375.4 kg / h (2-methyltetrahydrofuran content 33.3 wt%, water content 0.1 wt%, n-heptane content 66.6 wt%), and the waste water discharge was 263.8 kg / h.

[0120] The desolventizing column in step (4) had 36 plates, a reflux ratio of 2, and a pressure of 0.07 MPa. The overhead temperature of the desolventizing column was 86°C, and the 2-methyltetrahydrofuran product output was 1124.1 kg / h (2-methyltetrahydrofuran purity 99.2 wt%). The solvent n-heptane was discharged from the column bottom, the column bottom temperature was 129°C, and the n-heptane output was 2251.1 kg / h (n-heptane content 98.4 wt%, 2-methyltetrahydrofuran content 1.6 wt%).

[0121] The heavy component removal column in step (5) had 32 plates, a reflux ratio of 4, and a pressure of 0.1 MPa. The overhead temperature of the heavy component removal column was 176°C, and the tetrahydrofurfuryl alcohol product output was 185.0 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities were discharged from the column bottom, the column bottom temperature was 211°C, and the heavy component output was 74.2 kg / h (heavy component content 99.1 wt%, tetrahydrofurfuryl alcohol content 0.9 wt%).

[0122] Under these conditions, the qualified products were obtained, the 2-methyltetrahydrofuran yield was 83.6%, and the tetrahydrofurfuryl alcohol yield was 11.6%.

[0123] Example 6

[0124] Using the device as described in Figure 1 A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, the steps are as follows:

[0125] In step (1), 1200.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) were continuously fed to a mixer by a pump, the mass ratio of furfural to n-heptane was 1:0.5, and the continuous feeding amount of hydrogen (purity 99.9 vol%) was 200.0 kg / h.

[0126] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 40, the reactant furfural and n-heptane are fed into the column at the 10th plate and the 18th plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 25th theoretical plate. The 10th-25th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 27.8 kg, and the reflux ratio is 3.8. The top temperature of the distillation column is 184°C, a partial condenser is used, the pressure is controlled at 2.4 MPa, and the top output is 1797.6 kg / h (2-methyltetrahydrofuran content is 51.2 wt%, water content is 10.7 wt%, n-heptane content is 34.4 wt%, and hydrogen content is 4.6 wt%). The bottom temperature is 296°C, the heat is provided by the reaction heat of furfural hydrogenation reaction and the reboiler, and the bottom output is 204.0 kg / h (tetrahydrofurfuryl alcohol content is 73.2 wt%, and heavy component impurity content is 26.8 wt%).

[0127] The Cu-Pd / HY supported catalyst is used in the reaction process in step (2), and the preparation steps of the catalyst are as follows:

[0128] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water, and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of the raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.53: 1.90: 50: 4.25.

[0129] (b) The mixed solution obtained in step (a) is dried at 110°C and normal pressure for 12 hours under air atmosphere to obtain a catalyst precursor.

[0130] (c) The catalyst precursor obtained in step (b) is calcined at 500°C under air atmosphere and normal pressure in a muffle furnace for 8 hours to obtain a Cu-Pd / HY supported catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 5.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500°C at a rate of 5°C / min, then the temperature is kept constant for 3 hours of reduction, the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0131] The overhead product of the reactive distillation column in step (3) was cooled to -5°C by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 101.6 kg / h (2-methyltetrahydrofuran content 7.3 wt%, water content 0.7 wt%, n-heptane content 2.1 wt%, hydrogen content 89.9 wt%), the oil phase output was 1503.4 kg / h (2-methyltetrahydrofuran content 60.0 wt%, water content 0.1 wt%, n-heptane content 39.9 wt%), and the waste water discharge was 192.6 kg / h.

[0132] The desolventizing column in step (4) had 32 plates and a reflux ratio of 2. The overhead temperature of the desolventizing column was 94°C, and the 2-methyltetrahydrofuran product output was 902.0 kg / h (2-methyltetrahydrofuran purity 99.3 wt%). The solvent n-heptane was taken from the column bottom, the column bottom temperature was 149°C, and the n-heptane output was 600.9 kg / h (n-heptane content 98.6 wt%, 2-methyltetrahydrofuran content 1.4 wt%).

[0133] The heavy component column in step (5) had 28 plates, a reflux ratio of 4, and a pressure of 0.08 MPa. The overhead temperature of the heavy component column was 169°C, and the tetrahydrofurfuryl alcohol product output was 149.3 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities were taken from the column bottom, the column bottom temperature was 207°C, and the heavy component output was 54.7 kg / h (heavy component content 99.3 wt%, tetrahydrofurfuryl alcohol content 0.7 wt%).

[0134] Under these conditions, the qualified products were obtained, the 2-methyltetrahydrofuran yield was 83.9%, and the tetrahydrofurfuryl alcohol yield was 11.7%.

[0135] Example 7

[0136] Using the device as described in Figure 1 A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenation of furfural, the steps are as follows:

[0137] In step (1), 1200.0 kg / h of furfural (purity 99.5 wt%) and n-heptane (purity 99.3 wt%) were continuously sent to the mixer by the delivery pump after being pressurized, the mass ratio of furfural to n-heptane was 1:0.5, and the continuous feeding amount of hydrogen (purity 99.9 vol%) was 200.0 kg / h.

[0138] The operating parameters of the reactive distillation column in step (2) are as follows: the number of theoretical plates is 40, the reactant furfural and n-heptane are fed into the column at the 14th plate and the 22nd plate respectively, the feeding branch is connected with a distributor to uniformly distribute the liquid phase, and the hydrogen feeding position is at the 29th theoretical plate. The 14th to 29th theoretical plates of the reactive distillation column are divided into two reaction sections for feeding respectively, the filling amount of the Cu-Pd / HY supported catalyst is 27.8 kg, and the reflux ratio is 3.8. The top temperature of the distillation column is 161℃, a partial condenser is used, the pressure is controlled at 1.8 MPa, and the top output is 1732.66 kg / h (2-methyltetrahydrofuran content is 49.7 wt%, water content is 12.5 wt%, n-heptane content is 34.7 wt%, and hydrogen content is 3.1 wt%). The bottom temperature is 271℃, the heat is provided by the reaction heat of furfural hydrogenation reaction and the reboiler, and the bottom output is 268.1 kg / h (tetrahydrofurfuryl alcohol content is 49.0 wt%, and heavy component impurity content is 51.0 wt%).

[0139] In step (2), the Cu-Pd / HY supported catalyst is used in the reaction process, and the preparation steps of the catalyst are as follows:

[0140] (a) Pd acetate (purity 99 wt%), copper nitrate trihydrate (purity 99 wt%), deionized water and HY molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., NKF-7-2QD5.0 (HY) molecular sieve, silicon-aluminum ratio 5.4) are stirred and mixed at room temperature and normal pressure for 8 hours to obtain a mixed solution. The mass ratio of raw materials Pd acetate: copper nitrate trihydrate: deionized water: HY molecular sieve is 0.53: 1.90: 50: 4.25.

[0141] (b) The mixed solution obtained in step (a) is dried at 110℃ under air atmosphere and normal pressure for 12 hours to obtain a catalyst precursor.

[0142] (c) The catalyst precursor obtained in step (b) is calcined in a muffle furnace under air atmosphere, normal pressure and 500℃ for 8 hours to obtain a Cu-Pd / HY supported catalyst. The Cu content of the catalyst is 10.0 wt% and the Pd content is 5.0 wt% based on the mass of the catalyst. Before use, the Cu-Pd / HY catalyst needs to be reduced, and the reduction conditions are as follows: the reduction gas is hydrogen / nitrogen mixed gas containing 5%vol hydrogen, the temperature is raised to 500℃ at a rate of 5℃ / min, then the temperature is kept constant for 3 hours, and the flow rate of the hydrogen / nitrogen mixed gas is 0.002 Nm 3 / h.

[0143] The overhead product of the reactive distillation column in step (3) was cooled to -5℃ by a chiller, and the operating pressure of the phase separator was 1.9 MPa. The gas phase output of the phase separator was 53.3 kg / h (2-methyltetrahydrofuran content 7.5 wt%, water content 0.4 wt%, n-heptane content 1.4 wt%, hydrogen content 90.7 wt%), the oil phase output was 1462.1 kg / h (2-methyltetrahydrofuran content 58.9 wt%, water content 0.1 wt%, n-heptane content 41.0 wt%), and the waste water discharge was 217.3 kg / h.

[0144] The desolventizing column in step (4) had 32 trays, a reflux ratio of 2, and a pressure of 0.09 MPa. The overhead temperature of the desolventizing column was 93℃, and the 2-methyltetrahydrofuran product output was 861.7 kg / h (2-methyltetrahydrofuran purity 99.0 wt%). The solvent n-heptane was discharged from the column bottom, the column bottom temperature was 150℃, and the n-heptane output was 600.4 kg / h (n-heptane content 98.9 wt%, 2-methyltetrahydrofuran content 1.1 wt%).

[0145] The heavy component column in step (5) had 28 trays, a reflux ratio of 4, and a pressure of 0.08 MPa. The overhead temperature of the heavy component column was 169℃, and the tetrahydrofurfuryl alcohol product output was 131.4 kg / h (tetrahydrofurfuryl alcohol purity 99.9 wt%). The heavy component impurities were discharged from the column bottom, the column bottom temperature was 209℃, and the heavy component output was 136.7 kg / h (heavy component content 99.1 wt%, tetrahydrofurfuryl alcohol content 0.9 wt%).

[0146] Under these conditions, the qualified product was obtained, the 2-methyltetrahydrofuran yield was 80.1%, and the tetrahydrofurfuryl alcohol yield was 10.3%.

[0147] The part of the present application not described in detail belongs to the known technology of the person skilled in the art. The above-described embodiments only describe the preferred embodiments of the present application, and the preferred embodiments do not describe all the details and limit the present application to the specific embodiments described. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by the person skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for simultaneously preparing 2-methyltetrahydrofuran and tetrahydrofurfuryl alcohol by hydrogenating furfural, characterized in that: The method comprises the following steps: (1) Furfural and solvent n-heptane are pumped into a mixer, mixed, and then fed into the feed main pipeline of the reactive distillation tower; fresh hydrogen and recycled hydrogen are transported to the air inlet of the reactive distillation tower by a compressor; (2) The mixed liquid of furfural and n-heptane is transported from the feed main to the top of the reaction section of the reaction distillation tower, and hydrogen is transported to the air inlet at the bottom of the reaction section of the reaction distillation tower; furfural and hydrogen undergo a one-step continuous hydrogenation reaction in the reaction section of the reaction distillation tower to generate 2-methyltetrahydrofuran, tetrahydrofurfuryl alcohol and heavy component impurities mainly consisting of ester substances generated by hydrogenation and rearrangement of furfuryl alcohol; the reaction section of the reaction distillation tower adopts a Cu-Pd / HY supported bimetallic catalyst, wherein the weight percentage of Cu is 100% by weight based on the total weight. The content of Pd is 8wt%~15wt%, and the weight percentage of Pd is 0.5wt%~12wt%; the reaction product is separated in the distillation section and the stripping section, and 2-methyltetrahydrofuran, water and hydrogen are extracted from the top of the tower, and the solvent n-heptane, tetrahydrofurfuryl alcohol and heavy component impurities are extracted from the bottom of the tower; the reactive distillation tower is a packed tower, and the operating pressure of the reactive distillation tower is 1.8~2.5MPa, the operating temperature is 150~340℃, the number of theoretical plates is 30~80, and the reflux ratio is 2~5; (3) The top product of the reactive distillation tower is cooled to -5~5℃ in a cryogenic refrigerator and then transported to a phase separator for three-phase separation. The phase separator is pressurized at 1.8~2.4MPa. After static separation, the oil phase is collected to obtain a mixture of 2-methyltetrahydrofuran and n-heptane, which is then pumped to a desolventizing tower. The non-condensable gas at the top of the phase separator is mainly hydrogen, which is compressed by a compressor and then reused. (4) The oil phase of the phase separator is continuously sent to the desolventizing tower by a pump, and the solvent n-heptane obtained in the tower bottom is directly mixed with furfural and then returned to the reactive distillation tower. The top of the tower is 2-methyltetrahydrofuran product, which is pumped to the 2-methyltetrahydrofuran storage tank by a pump; the desolventizing tower is a structured packing or random packing distillation tower; the number of theoretical plates of the desolventizing tower is 30~60; the operating conditions of the desolventizing tower are: 0.04~0.09MPa, the top temperature is 70~96℃, the bottom temperature is 107~158℃, and the reflux ratio is 1~4; (5) The product from the bottom of the reactive distillation tower is continuously sent to the deweighting tower through a pump, and tetrahydrofurfuryl alcohol is obtained at the top of the deweighting tower, with a tetrahydrofurfuryl alcohol content of ≥99%, and the bottom of the tower is a heavy component impurity; the deweighting tower is a distillation tower with structured packing or random packing; the number of theoretical plates of the desolventizing tower is 28~60; the operating conditions of the deweighting tower are: 0.06~0.12MPa, the top temperature is 152~195℃, the bottom temperature is 198~254℃, and the reflux ratio is 2~5.

2. The method according to claim 1, characterized in that In step (1), n-heptane is selected as the solvent, and furfural and n-heptane are mixed in a mass ratio of 1:0.2-4 and then input into the feed main pipeline of the reactive distillation tower.

3. The method according to claim 1, characterized in that In step (2), the reaction distillation tower is operated continuously, with a tower top temperature of 150-180°C, a reaction zone temperature of 210-250°C, and a tower bottom temperature of 250-310°C.

4. The method according to claim 1, wherein In step (2), the reaction distillation tower is provided with a packing layer and a catalyst layer from top to bottom, the height of each catalyst layer is 1.5 to 4 meters, and the number of catalyst layers is 1 to 3 layers; a distributor is provided above each section, and the distributors are respectively connected to the main feed pipeline of the reaction distillation tower.

5. The method according to claim 1, wherein In step (2), the total theoretical number of plates of the reactive distillation is 30 to 80, wherein the theoretical number of plates in the reaction section is 10 to 30 and the theoretical number of plates in the distillation section is 20 to 50; furfural is fed from above the reaction section, and hydrogen is fed from below the reaction section.

6. The method according to claim 1, characterized in that In step (3), the non-condensable gas discharged from the phase separator is hydrogen, which is used as recycled hydrogen and then pressurized by a hydrogen compressor and returned to the reaction distillation tower for recycling.

7. The method according to claim 1, characterized in that The distillation steps described in steps (4) and (5) are two towers operated in series, and n-heptane is removed from the top of the desolventizing tower and reused in the reactive distillation tower; the material at the bottom of the desolventizing tower enters the deweighting tower, and the heavy component impurities are removed in the deweighting tower, and the tetrahydrofurfuryl alcohol product is obtained at the top of the tower.

8. The method according to claim 1, characterized in that In step (2), the packing of the reactive distillation tower is structured packing and / or random packing, and the packing material is stainless steel; In step (4), the filler and tower body of the desolventizing tower are made of stainless steel; In step (5), the filler and tower body of the deweighting tower are made of stainless steel.

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