A continuous process for the preparation of 1,3-dihydroisobenzofurans and catalysts used therein

Abstract

The application discloses a continuous preparation method of 1,3-dihydroisobenzofuran, which is carried out according to the following steps: (1) loading a catalyst into a reactor, introducing a carrier gas into the reactor, and activating the catalyst by heating, and adjusting the reaction temperature to a target reaction temperature after the activation is completed; (2) adding a reaction raw material, hexahydroisobenzofuran, into the reactor to carry out a reaction, and after the raw material contacts with a catalyst bed, the raw material is separated from the reactor under the driving of the carrier gas, enters a condenser and a gas-liquid separator, and then enters a product storage tank, and tail gas is exhausted; and (3) the product in the storage tank is subjected to vacuum rectification to obtain a product with a purity of more than 97%. The reaction has high selectivity, fundamentally solves the problems of high operation difficulty and cost in the traditional method, greatly reduces the difficulty of subsequent separation, further reduces production energy consumption and production cost, and is easy to realize industrialized production.

Description

Technical Field

[0001] This application relates to the field of chemical synthesis, and more specifically, to a method for the continuous preparation of 1,3-dihydroisobenzofuran from hexahydroisobenzofuran (IBF) by dehydrogenation, a catalyst used in the method, and the use of the catalyst in the continuous preparation of 1,3-dihydroisobenzofuran. Background Technology

[0002] 1,3-Dihydroisobenzofuran 1,3-Dihydroisobenzofuran is an important oxygen-containing heterocyclic compound, widely found in natural products and drug molecules. It possesses biological activities such as antibacterial, antidepressant, anti-HIV, and antihistamine effects, and is also an important component of organic synthesis. The 1,3-dihydroisobenzofuran skeleton frequently appears in compounds with biological and pharmaceutical activities, representing a very important structural unit. Many clinically used drugs contain the 1,3-dihydroisobenzofuran ring structure, making it highly active in the chemical and pharmaceutical fields. It has been reported that 1,3-dihydroisobenzofuran can be oxidized to synthesize phthalaldehyde. Phthalate is an important pharmaceutical and chemical intermediate, previously mainly used in amine alkaloids, reagents for histamine determination using fluorescence spectrometers, and pharmaceutical testing. Since its use for endoscopic disinfection in 1994, where its excellent disinfection effect was discovered, numerous studies have been conducted abroad on the disinfection properties of phthalaldehyde, leading to its development as a novel and highly effective disinfectant that has received FDA approval in the United States. The reaction process for synthesizing 1,3-dihydroisobenzofuran from o-xylene / o-phthalimide is as follows:

[0003]

[0004] Currently, the main methods for synthesizing 1,3-dihydroisobenzofuran involve the reaction of o-bis(chloromethyl)benzene with sodium hydroxide under a phase transfer catalyst, or the dehydration of o-phthalimethanol under acid catalysis. However, the o-bis(chloromethyl)benzene required for these processes is primarily produced through the chlorination of o-xylene. The chlorination reaction typically yields a mixture of monochloro, dichloro, and trichloro derivatives, making it difficult to obtain the monochloro derivative with high selectivity. Product separation and waste treatment are the key challenges of this process. Summary of the Invention

[0005] To address the aforementioned technical problems, the present application aims to provide a continuous preparation method for 1,3-dihydroisobenzofuran and the catalyst used therein. This method uses hexahydroisobenzofuran as a raw material and prepares 1,3-dihydroisobenzofuran through a continuous dehydrogenation reaction. The continuous preparation method for 1,3-dihydroisobenzofuran according to this application exhibits extremely excellent catalytic activity and target selectivity, capable of catalyzing the dehydrogenation of hexahydroisobenzofuran to prepare the target product 1,3-dihydroisobenzofuran with a conversion rate exceeding 99%.

[0006] To achieve the above objectives, according to one aspect of the present invention, one object of the present invention is to provide a continuous method for preparing 1,3-dihydroisobenzofuran, said method being carried out according to the following steps:

[0007] (1) The catalyst is loaded into the reactor, the carrier gas is introduced into the reactor, and the catalyst is activated by heating. After activation, the reaction temperature is adjusted to the target reaction temperature.

[0008] (2) The reaction raw material hexahydroisobenzofuran is added to the reactor for reaction. After the raw material comes into contact with the catalyst bed, it leaves the reactor under the action of the carrier gas, enters the condenser and gas-liquid separator, and then enters the product storage tank. The tail gas is discharged into the air.

[0009] (3) The product in the storage tank can be obtained by vacuum distillation to obtain a product with a purity of over 97%.

[0010] According to one embodiment of this application, the reactor in the continuous preparation method of 1,3-dihydroisobenzofuran is selected from any one of a continuous stirred tank reactor, a plug flow reactor, a fixed phase reactor, and a fluidized bed reactor, or it can be a mixed reactor consisting of two or more of these reactors connected together. Preferably, it is a fixed bed reactor.

[0011] According to one embodiment of this application, in step (1), the catalytic activator is heated to 200-500°C and the activation time is 1-6 hours; the target reaction temperature is 280-400°C, preferably 300-350°C;

[0012] According to one embodiment of this application, in step (1), the mass hourly space velocity (HHSV) of the continuous preparation method of 1,3-dihydroisobenzofuran is 0.1–0.8 h⁻¹. -1 Preferably 0.3–0.6 h -1 ;

[0013] According to one embodiment of this application, in step (1), the raw material hexahydroisobenzofuran can be dissolved in one or more solvents selected from methanol, ethanol, propanol, acetone, cyclohexene, n-hexene, and tetrahydrofuran, or it can be fed without solvent.

[0014] According to one embodiment of this application, in step (1), when hexahydroisobenzofuran is fed with a solvent, the mass concentration in the solvent is 5-40 wt%, preferably 10-30 wt%.

[0015] According to one embodiment of this application, in step (1), the carrier gas includes one or more of nitrogen, hydrogen, helium, and argon;

[0016] According to one embodiment of this application, in step (3), the distillation temperature is 50-55°C and the pressure is 300-400Pa;

[0017] With the technical solution provided by this invention, under the above reaction conditions, the conversion rate of hexahydroisobenzofuran is 96-99%, and the selectivity of 1,3-dihydroisobenzofuran is >80%.

[0018] Another object of this application is to provide a catalyst for use in the continuous preparation method of the 1,3-dihydroisobenzofuran, said catalyst being prepared by a method comprising the following steps:

[0019] (1) Impregnate the active component precursor solution and carrier by an equal volume, ensuring thorough impregnation;

[0020] (2) Dry the mixture from step (1);

[0021] (3) The substance obtained in step (2) is calcined under a nitrogen atmosphere to obtain a catalyst precursor;

[0022] (4) The catalyst precursor obtained in step (3) is packed into a reaction tube and reduced in a hydrogen atmosphere to obtain the catalyst of the present invention.

[0023] According to one embodiment of this application, the active component precursor is selected from one or more of the chloride, nitrate, and acetate salts of Pt, Pd, Ru, Ir, Ni, and Cu;

[0024] Preferably, the concentration of the aqueous solution of the active component precursor is 0.005 mol / L to 0.05 mol / L;

[0025] According to one embodiment of this application, the support is selected from one or more of activated carbon, γ-Al2O3, SiO2, ZrO2, TiO2, HZSM5, SAPO-34, HY, Hβ and HMOR;

[0026] Preferably, the mass ratio of the metal element to the carrier in the active component is (0.2-2.5):100;

[0027] According to one embodiment of this application, in step (1),

[0028] Preferably, the immersion temperature is 20–40°C; the immersion time is 4–6 hours.

[0029] According to one embodiment of this application, in step (2),

[0030] Preferably, the drying temperature is 110℃~150℃, more preferably 110~130℃; the drying time is 10h~12h.

[0031] According to one embodiment of this application, in step (3),

[0032] Preferably, the calcination temperature is 400–600℃ and the calcination time is 5–8 hours;

[0033] According to one embodiment of this application, in step (4),

[0034] Preferably, the catalytic reduction temperature is 350–400℃, and the reduction time is 3–5 h;

[0035] Preferably, the catalyst precursor has a particle size of 20-40 mesh.

[0036] According to one embodiment of this application, the carrier is further subjected to pretreatment: before step (1), the carrier is calcined in air at 200°C to 400°C for 2 to 5 hours.

[0037] Another object of this application is to provide the use of the catalyst in a continuous method for the preparation of 1,3-dihydroisobenzofuran.

[0038] Another object of this application is to provide a method for preparing hexahydroisobenzofuran used in the continuous preparation method of the aforementioned 1,3-dihydroisobenzofuran, the preparation method comprising the following steps:

[0039] 2,5-Dihydrofuran was added to the reactor, and then 1,3-butadiene was continuously introduced into it until all the 1,3-butadiene was added. The reactor was sealed, and the air inside the reactor was replaced with nitrogen three times. After restoring the pressure to atmospheric, the reactor was heated with stirring. After the reaction was completed, the temperature was lowered, and 2,5-Dihydrofuran was recovered by atmospheric distillation. Hexahydroisobenzofuran was obtained by vacuum distillation.

[0040] Preferably, the mass ratio of 2,5-dihydrofuran to 1,3-butadiene is 5:1 to 1:5;

[0041] Preferably, the reaction is carried out at 180°C with stirring for 6 hours;

[0042] Preferably, the temperature for atmospheric distillation to recover 2,5-dihydrofuran is 62°C;

[0043] Preferably, the vacuum distillation temperature is 50-52℃ and the pressure is 350-400Pa.

[0044] Beneficial effects

[0045] The catalyst provided in this application for the synthesis of 1,3-dihydroisobenzofuran can catalyze the dehydrogenation reaction of hexahydroisobenzofuran with high conversion rate and high selectivity (>80%). It fundamentally solves the problems of high operation difficulty and high cost in traditional methods, greatly reduces the difficulty of subsequent separation, and eliminates the need for complex distillation operations to obtain high-purity 1,3-dihydroisobenzofuran. This further reduces production energy consumption, lowers production costs, and facilitates industrial production. Attached Figure Description

[0046] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of a synthesis apparatus for 1,3-dihydroisobenzofuran according to one embodiment of this application;

[0048] Figure 2 The gas chromatogram of the dehydrogenation reaction products according to Reaction Example 8 of this application;

[0049] Figure 3 The chromatogram of the distillation separation product according to reaction example 8 of this application is shown. Detailed Implementation

[0050] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general and dictionary meaning, but rather should be interpreted based on the principle of allowing the inventors to appropriately define the terminology for the best interpretation, and based on its meaning and concept corresponding to the technical level of the invention. Therefore, the description herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention; thus, it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the invention.

[0051] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0052] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0053] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0054] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0055] The following embodiments are merely examples of implementation schemes of this application and do not constitute any limitation on this application. Those skilled in the art will understand that any modifications that do not depart from the essence and concept of this application fall within the protection scope of this application.

[0056] Preparation of 1,3-dihydroisobenzofuran

[0057] In the continuous preparation method of 1,3-dihydroisobenzofuran according to this application, hexahydroisobenzofuran is used as a raw material, and 1,3-dihydroisobenzofuran is obtained through a dehydration reaction. The product obtained after post-processing is analyzed by gas chromatography (GC). Qualitative analysis of the low-boiling-point product is performed by GC-MS and comparison with the GC retention time of the standard, confirming that the main reaction product is 1,3-dihydroisobenzofuran. Quantitative determination of the low-boiling-point substance is performed using a Shimadzu-GC 2020 gas chromatograph, and quantitative analysis is performed by comparing the retention time with the standard and the peak area. The relevant calculation formulas are as follows:

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] The flow rate of hexahydroisobenzofuran is expressed in g / min, and the amount of catalyst is expressed in g.

[0064] like Figure 1 The diagram shows a schematic of a reaction apparatus for synthesizing 1,3-dihydroisobenzofuran according to one embodiment of this application. The reaction tube is filled with a catalyst according to this application for the preparation of 1,3-dihydroisobenzofuran. First, a carrier gas is introduced into the reaction tube at a controlled flow rate using a mass flow meter to create a carrier gas atmosphere. A furnace can then be used to heat and activate the catalyst. Next, while maintaining the temperature of the reaction tube, hexahydroisobenzofuran is fed into the reaction tube via a feed pump. Under the carrier gas atmosphere and with the catalyst catalyzing, the reaction produces a product containing 1,3-dihydroisobenzofuran. After condensation and gas-liquid separation, 1,3-dihydroisobenzofuran can be collected.

[0065] Unless otherwise specified, all raw materials used in this application are commercially available, and all methods and equipment used are conventional methods and equipment in the field.

[0066] In the following examples, hexahydroisobenzofuran was prepared in-house and synthesized as follows: 1000 L of 2,5-dihydrofuran was added to a 3 L reactor, and then 1,3-butadiene was continuously introduced until approximately 500 g of 1,3-butadiene was added. The reactor was sealed, and the air inside was replaced three times with nitrogen. After restoring to atmospheric pressure, the reactor was heated to 180 °C for 6 hours with stirring. After the reaction was completed, the temperature was lowered, and 2,5-dihydrofuran was recovered by atmospheric distillation (62 °C). Then, approximately 300 g of hexahydroisobenzofuran was obtained by vacuum distillation (300-400 Pa, 50-55 °C).

[0067] Chloroplatinic acid hexahydrate, palladium acetate, nickel nitrate, zinc nitrate hexahydrate, aluminum nitrate nonahydrate, potassium carbonate, and ammonia were purchased from Sinopharm Chemical Reagent Co., Ltd.; high-purity nitrogen, high-purity helium, and air were purchased from Qingdao Dehai Weiye Technology Co., Ltd.

[0068] Catalyst preparation

[0069] Preparation Example 1

[0070] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0071] (i) Pretreatment of the support: 50g of support γ-Al2O3 was calcined at 300℃ in air atmosphere for 5h;

[0072] (ii) Add 13g of 3.8% chloroplatinic acid aqueous solution and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and soak for 5 hours.

[0073] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0074] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0075] (v) The product obtained in step (iv) was reduced at 250 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thereby obtaining catalyst one.

[0076] Preparation Example 2

[0077] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0078] (i) Pretreatment of the support: 50g of SiO2 support was calcined at 300℃ in air atmosphere for 5h;

[0079] (ii) Add 40g of 3.8% palladium acetate aqueous solution and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and immerse for 5 hours.

[0080] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0081] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0082] (v) The product obtained in step (iv) was reduced at 300 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thereby obtaining catalyst II.

[0083] Preparation Example 3

[0084] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0085] (i) Pretreatment of the carrier: 50g of carrier Hβ was calcined at 300℃ in air atmosphere for 5h;

[0086] (ii) The pretreated carrier obtained in step (i) is added to 65g of a 3.8% nickel nitrate aqueous solution and an appropriate amount of deionized water and impregnated for 5 hours.

[0087] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0088] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0089] (v) The product obtained in step (iv) was reduced at 350 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst three was prepared.

[0090] Preparation Example 4

[0091] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0092] (i) Pretreatment of the carrier: 50g of carrier HZSM5 was calcined at 300℃ in air atmosphere for 5h;

[0093] (ii) Add 105g of 3.8% chloroplatinic acid aqueous solution and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and soak for 5 hours.

[0094] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0095] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0096] (v) The product obtained in step (iv) was reduced at 300 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst four was prepared.

[0097] Preparation Example 5

[0098] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0099] (i) Pretreatment of the carrier: 50g of carrier HY was calcined at 300℃ in air atmosphere for 5h;

[0100] (ii) Add 131g of 3.8% platinum nitrate aqueous solution and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and immerse for 5 hours.

[0101] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0102] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0103] (v) The product obtained in step (iv) was reduced at 300 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst five was prepared.

[0104] Preparation Example 6

[0105] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0106] (i) Pretreatment of the carrier: 50g of carrier activated carbon was calcined at 200°C in air atmosphere for 5h;

[0107] (ii) The pretreated carrier obtained in step (i) is added to 131g of 3.8% palladium nitrate aqueous solution and an appropriate amount of deionized water and impregnated for 5h.

[0108] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0109] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0110] (v) The product obtained in step (iv) was reduced at 250 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst six was prepared.

[0111] Preparation Example 7

[0112] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0113] (i) Pretreatment of the carrier: 50g of carrier activated carbon was calcined at 200°C in air atmosphere for 5h;

[0114] (ii) Add 131g of 3.8% platinum nitrate aqueous solution and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and immerse for 5 hours.

[0115] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0116] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0117] (v) The product obtained in step (iv) was reduced at 300 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst seven was prepared.

[0118] Preparation Example 8

[0119] A catalyst for the preparation of 1,3-dihydroisobenzofuran is prepared by a method including the following steps:

[0120] (i) Pretreatment of the support: 50g of SiO2 support was calcined at 200℃ in air atmosphere for 5h;

[0121] (ii) Add 131g of copper nitrate aqueous solution with a mass concentration of 6% and an appropriate amount of deionized water to the pretreated carrier obtained in step (i) and soak for 5 hours.

[0122] (iii) Dry the product obtained in step (ii) in an oven at 120°C for 12 hours;

[0123] (iv) The product obtained in (iii) was calcined at 500°C under a nitrogen atmosphere for 6 h;

[0124] (v) The product obtained in step (iv) was reduced at 230 °C in a hydrogen atmosphere for 4 h, wherein the hydrogen flow rate was 50 mL / min; thus, catalyst eight was prepared.

[0125] Reaction Example 1

[0126] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0127] (a) 10 g of the shaped catalyst from Preparation Example 1 was added to a fixed-bed reactor, and the mixture was heated to 300°C under a nitrogen atmosphere; and

[0128] (b) At a reaction temperature of 300°C and atmospheric pressure, hexahydroisobenzofuran (solvent acetone, mass concentration 20 wt%) was reacted at a reaction rate of 0.6 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0129] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 52°C and a pressure of 380Pa.

[0130] Reaction Example 2

[0131] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0132] (a) 10 g of the shaped catalyst II from Preparation Example 2 was added to a fixed-bed reactor, and the temperature was raised to 320°C under a nitrogen atmosphere; and

[0133] (b) At a reaction temperature of 320°C and atmospheric pressure, hexahydroisobenzofuran (solvent cyclohexene, mass concentration 20 wt%) was reacted at a reaction rate of 0.4 h. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0134] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 50℃ and a pressure of 380-390Pa.

[0135] Reaction Example 3

[0136] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0137] (a) 10 g of the shaped catalyst III from Preparation Example 3 was added to a fixed-bed reactor, and the mixture was heated to 350 °C under a helium atmosphere; and

[0138] (b) At a reaction temperature of 350°C and atmospheric pressure, hexahydroisobenzofuran (solvent methanol, mass concentration 20 wt%) was reacted at a reaction rate of 0.3 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0139] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 54℃ and a pressure of 390-400Pa.

[0140] Reaction Example 4

[0141] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0142] (a) 10 g of the shaped catalyst IV from Preparation Example 4 was added to a fixed-bed reactor, and the mixture was heated to 360 °C under an argon atmosphere; and

[0143] (b) At a reaction temperature of 360°C and atmospheric pressure, hexahydroisobenzofuran was reacted at a rate of 0.5 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0144] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 52°C and a pressure of 360Pa.

[0145] Reaction Example 5

[0146] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0147] (a) 10 g of the shaped catalyst from Preparation Example 5 was added to a fixed-bed reactor, and the temperature was raised to 380°C under a hydrogen atmosphere; and

[0148] (b) At a reaction temperature of 380°C and atmospheric pressure, hexahydroisobenzofuran was reacted at a rate of 0.6 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0149] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 50°C and a pressure of 360Pa.

[0150] Reaction Example 6

[0151] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0152] (a) 10 g of the shaped catalyst from Preparation Example 6 was added to a fixed-bed reactor, and the temperature was raised to 350°C under a nitrogen atmosphere; and

[0153] (b) At a reaction temperature of 350°C and atmospheric pressure, hexahydroisobenzofuran was reacted at a rate of 0.3 h⁻¹. -1The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0154] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 52°C and a pressure of 380Pa.

[0155] Reaction Example 7

[0156] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0157] (a) 10 g of the shaped catalyst VII from Preparation Example 7 was added to a fixed-bed reactor, and the mixture was heated to 350 °C under a nitrogen atmosphere; and

[0158] (b) At a reaction temperature of 350°C and atmospheric pressure, hexahydroisobenzofuran was reacted at a rate of 0.3 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0159] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 50°C and a pressure of 400Pa.

[0160] Reaction Example 8

[0161] A method for preparing 1,3-dihydroisobenzofuran using the following steps:

[0162] (a) 10 g of the shaped catalyst from Preparation Example 8 was added to a fixed-bed reactor, and the temperature was raised to 280°C under a hydrogen atmosphere; and

[0163] (b) At a reaction temperature of 380°C and atmospheric pressure, hexahydroisobenzofuran was reacted at a rate of 0.4 h⁻¹. -1 The gas was introduced into the reactor at a space velocity to carry out the reaction. Samples were taken and the products were analyzed by GC chromatography. The detection results showed no significant changes, and the reaction was stable. The reaction results are shown in Table 1.

[0164] (c) The product mixture was distilled using an 80cm glass fiber packed column with a 1,3-dihydroisobenzofuran head temperature of 52°C and a pressure of 400Pa.

[0165] Appendix 1

[0166]

[0167] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A continuous preparation method for 1,3-dihydroisobenzofuran, characterized in that, The method is performed according to the following steps: (1) The catalyst is loaded into a fixed-bed reactor, a carrier gas is introduced into the reactor, and the catalyst is activated by heating. After activation, the reaction temperature is adjusted to the target reaction temperature, wherein the heating activation is to raise the temperature to 200~500°C and the activation time is 1-6 h; the target reaction temperature is 280~400°C, and the mass hourly space velocity of the continuous preparation method of 1,3-dihydroisobenzofuran is 0.1~0.8 h. -1 When feeding hexahydroisobenzofuran, it can be dissolved in one or more solvents selected from methanol, ethanol, propanol, acetone, cyclohexene, n-hexene, and tetrahydrofuran, or it can be fed without solvent. (2) The reactant hexahydroisobenzofuran is added to a fixed-bed reactor for reaction. After the reactant comes into contact with the catalyst bed, it leaves the reactor under the action of the carrier gas and enters the condenser and gas-liquid separator before entering the product storage tank. The tail gas is discharged into the air. (3) The product in the storage tank can be obtained with a purity of over 97% by vacuum distillation. The distillation temperature is 50-52℃ and the pressure is 300-400Pa. The catalyst is prepared by the following steps: (1) Impregnate the active component precursor solution and carrier by an equal volume, ensuring thorough impregnation; (2) Dry the mixture from step (1); (3) The substance obtained in step (2) is calcined under a nitrogen atmosphere to obtain a catalyst precursor; (4) The catalyst precursor obtained in step (3) is packed into a reaction tube and reduced under a hydrogen atmosphere to obtain the catalyst: In the method for preparing the catalyst: (h) The active component precursor is selected from one or more of the chloride, nitrate, and acetate salts of Pt, Pd, Ni, and Cu; (i) The concentration of the aqueous solution of the active component precursor is 0.005 mol / L to 0.05 mol / L; (j) The support is selected from one or more of activated carbon, γ-Al2O3, SiO2, HZSM5, HY and Hβ; (k) The mass ratio of the metal element to the carrier in the active component is (0.2~2.5):100; (l) In step (1), the immersion temperature is 20~40°C; the immersion time is 4 h~6 h; (m) In step (2), the drying temperature is 110℃~150℃ and the drying time is 10h~12h; (n) In step (3), the calcination temperature is 400~600°C and the calcination time is 5~8h; (o) In step (4), the catalytic reduction temperature is 350~400°C and the reduction time is 3~5h; the particle size of the catalyst precursor is 20-40 mesh.

2. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, In step (1), the target reaction temperature is 300~350°C.

3. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, In step (1), the mass hourly space velocity (HHSV) of the continuous preparation method of 1,3-dihydroisobenzofuran is 0.3~0.6 h⁻¹. -1 .

4. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, In step (1), when hexahydroisobenzofuran is fed with a solvent, the mass concentration in the solvent is 5-40 wt%.

5. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, When hexahydroisobenzofuran is fed with a solvent, its mass concentration in the solvent is 10-30 wt%.

6. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, In step (1), the carrier gas is selected from one or more of nitrogen, hydrogen, helium, and argon.

7. The continuous preparation method of 1,3-dihydroisobenzofuran according to any one of claims 1 to 6, characterized in that, The conversion rate of hexahydroisobenzofuran is 96-99%, and the selectivity of 1,3-dihydroisobenzofuran is >80%.

8. The continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, In the preparation method of the catalyst, the drying temperature in step (2) is 110~130°C.

9. A continuous preparation method of 1,3-dihydroisobenzofuran according to claim 1, characterized in that, The preparation method of the catalyst further includes the pretreatment of the support: before step (1), the support is calcined in air at 200°C to 400°C for 2 h to 5 h.

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