Process for the synthesis of a pendant tetralactone by catalytic polymerization on a molecular sieve

Abstract

The application discloses a method for synthesizing a hanging type tetracyclododecene by molecular sieve catalytic polymerization, and the method is characterized in that a molecular sieve is added as a catalyst in a polymerization reaction of cyclopentadiene and norbornene, and the selectivity of the hanging type tetracyclododecene in the product is improved. In the method, SAPO-11 is used as the catalyst, the conversion rate is as high as 91.26%, the selectivity of the hanging type configuration isomer exo,exo-TCD is 37.71%, the added molecular sieve can be better separated from the system as a heterogeneous catalyst, and the post-treatment is more green and environment-friendly compared with the traditional catalyst.

Description

Technical Field

[0001] This invention belongs to the field of liquid fuel technology and relates to a method for synthesizing hanging tetracyclic dodecene by molecular sieve catalytic polymerization. Background Technology

[0002] Tetracyclododecene (dimethylene decahydronaphthalene) has a wide range of applications in high-density fuels, high-solids, low-viscosity acrylic resins or UV coatings, pharmaceutical synthesis, materials, and chemical industries due to its unique bridged ring structure. For example, tetracyclododecene obtained by saturated hydrogenation can effectively increase the net volumetric calorific value and density of fuels when used as fuels.

[0003] The synthesis of tetracyclododecene often uses dicyclopentadiene and norbornene as raw materials, and is accomplished through the Diels-Alder reaction. The Diels-Alder reaction (also known as the diene synthesis reaction) is a classic reaction for the efficient synthesis of multi-ring compounds from conjugated dienes and alkenes, and is widely used in the synthesis of high-energy-density fuels. The reaction products have two configurations: the bridged configuration isomer endo,exo-TCD and the hanging configuration isomer exo,exo-TCD, with the bridged configuration being the predominant one. However, the bridged tetracyclododecene obtained after saturated hydrogenation of the bridged product has poor low-temperature properties, existing in a solid state at room temperature, and does not meet the low-temperature performance requirements of fuels.

[0004] Patent CN112592248A reports a method for preparing tetracyclic dodecene compounds by using a diene synthesis reaction of norbornene and cyclopentadiene or dicyclopentadiene. Dicyclopentadiene and norbornene are reacted at a molar ratio of 1:(1-10), with the conversion rate of dicyclopentadiene reaching over 90%. After distillation purification, the purity of the tetracyclic dodecene compounds can reach over 98%. The main equipment includes a preheater, reactor, distillation column, and rectification column. This method does not introduce any solvent, reducing losses during distillation, and does not use ethylene gas or other olefins, reducing equipment investment. However, the product is mainly of a bridged configuration, exhibiting poor low-temperature performance.

[0005] Patent CN90107778.X reports a method for isomerizing cycloalkenes. As a pilot-scale reaction, a large amount of cyclohexane is used as a solvent and a silica-alumina catalyst is used to isomerize bridged tetracyclic dodecenes into hanging tetracyclic dodecenes. This method is time-consuming (96 hours), has a low hanging yield (<40%), and the catalyst post-treatment is relatively complicated.

[0006] In summary, the current methods for preparing tetracyclic dodecylene have the following problems: 1. The reaction apparatus is complex, which is not conducive to efficient production. 2. Traditional isomerization reactions initially used sulfuric acid, etc. Acid catalysts were initially used, with Lewis acid catalysts such as AlCl3 becoming more common. However, these catalysts are difficult to treat after use, hard to completely remove, cause significant environmental pollution, and generate byproducts such as alkyl adamantane. 3. The reaction time is long, typically over 20 hours. 4. Hanging-type catalysts have low selectivity, usually less than 40%.

[0007] Therefore, employing "green" catalysts to shorten reaction time and improve the selectivity of hanging tetracyclic dodecylenes is desirable. This invention aims to solve the aforementioned problems. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies. Addressing the difficulties in catalyst post-treatment, long reaction times, and low selectivity in the traditional isomerization process for preparing bridged cycloalkenes, this invention employs molecular sieve-catalyzed polymerization to improve the selectivity of the bridged product. Furthermore, the added molecular sieve, acting as a heterogeneous catalyst, allows for better separation from the system. The post-treatment process is also more environmentally friendly compared to traditional catalysts. The resulting bridged tetracyclododecene product, after saturated hydrogenation, yields bridged tetracyclododecane, which exhibits superior low-temperature performance.

[0009] This invention introduces a batch reactor for the catalytic polymerization of molecular sieves to achieve hanging tetracyclic [6,2,1,0] 2 ,7 ,1 3,6 The improvement of dodecene selectivity. Specifically, this involves adding reactants (norbornene and dicyclopentadiene) to a reaction vessel in a certain proportion, setting the temperature, pressure, and reaction time, and then adding different types of molecular sieves to carry out the reaction. The resulting products are then analyzed to explore their impact on the selectivity of the hang-type product. The technical solution adopted in this invention is:

[0010] This invention provides a method for synthesizing pedilicate tetracyclic dodecene via molecular sieve-catalyzed polymerization, characterized in that a molecular sieve is added as a catalyst in the polymerization reaction of cyclopentadiene and norbornene to improve the selectivity of pedilicate tetracyclic dodecene in the product. The method includes the following steps:

[0011] (1) Pretreatment of molecular sieves: The molecular sieve catalyst is calcined;

[0012] (2) To carry out the polymerization reaction:

[0013] (21) Add norbornene, dicyclopentadiene and the molecular sieve catalyst pretreated in step (1) to the reactor. After sealing the reactor, check whether the reactor is leaking. After confirming that the reactor is not leaking, proceed to the next step.

[0014] (22) Replace the air in the reactor with nitrogen, then heat and stir to carry out the reaction, and collect the product after the reaction is completed.

[0015] Preferably, in step (1), the calcination temperature is 550-650℃, the calcination time is 6-8h, and the calcination heating rate is 5-10℃ / min.

[0016] Preferably, in step (21), the mass ratio of norbornene, dicyclopentadiene and molecular sieve catalyst is 20:10:1 to 25:10:1.

[0017] Preferably, in step (21), the method for detecting whether the reactor is leaking is as follows: pressurize with nitrogen to a first pressure and maintain it for a first time. If the pressure does not change during the first time, it indicates that the reactor is not leaking. Then, unload the pressure and return to the initial pressure of 0 MPa. Repeat this process multiple times.

[0018] Preferably, in step (22), the reaction temperature is 170-200℃, the reaction time is 4-10h, and the stirring speed is 600-700r / min.

[0019] Preferably, after collecting the product in step (2), the reactor needs to be cleaned. The cleaning steps are as follows: add anhydrous ethanol to the reactor and clean it in an ultrasonic bath for 30 minutes, pour out the waste liquid, add ethanol to the reactor again, adjust the temperature to 0°C, adjust the rotation speed to 600 r / min, and clean it for another 30 minutes.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention uses an intermittent batch reactor for operation, which is simple to operate and suitable for large-scale preparation. Its industrial application prospects are becoming increasingly broad.

[0022] 2. This invention uses molecular sieve catalytic polymerization to improve the selectivity of hanging products. With SAPO-11 as catalyst, the conversion rate is as high as 91.26%, and the selectivity of hanging configuration isomers exo and exo-TCD is 37.71%. Furthermore, the added molecular sieve, as a heterogeneous catalyst, can be better separated from the system. Compared with traditional catalysts, the post-processing is more green and environmentally friendly. Attached Figure Description

[0023] Figure 1 Comparative Example 1: Product-time relationship diagram for different configurations.

[0024] Figure 2 Time-relationship diagram of different configuration products in Example 1 Detailed Implementation

[0025] The present invention will be further described below through embodiments, but is not limited to these embodiments. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in manuals, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified.

[0026] The specific steps of the preparation method in the following examples are as follows:

[0027] 1) Pretreatment of molecular sieves. Molecular sieves need to be calcined at high temperature before use to remove solvents, template agents and adsorbed moisture from the pores. The specific operation is as follows: Place the molecular sieve in the evaporating dish in a muffle furnace and heat it to 550°C at a heating rate of 5°C / min, and keep it for 6 hours.

[0028] 2) Add a certain amount of the mixture of DCPD, NBE, and the pretreated molecular sieves to a 100mL fully automated reactor. After sealing the reactor, pressurize it with nitrogen to 4MPa and maintain this pressure for 30 minutes to check for leaks. If the pressure remains essentially unchanged within 30 minutes, unload the pressure (i.e., the initial pressure is 0MPa). Repeat this process three times, replacing the air in the reactor with nitrogen. Then, raise the temperature to the set temperature, set the reaction time, and adjust the rotation speed to 600 rpm to begin the reaction. After the reaction, collect the product and perform subsequent characterization and analysis. Each experiment should be repeated at least three times. After each reaction, remove the product, add anhydrous ethanol to the reactor, and sonicate for 30 minutes. Discard the waste liquid, add ethanol again, adjust the temperature to 0℃, adjust the rotation speed to 600 rpm, and clean for another 30 minutes.

[0029] 3) By adding different molecular sieves, experiments were conducted to maximize the yield of hanging products.

[0030] Example 1

[0031] a. Place the SAPO-11 molecular sieve in the evaporating dish in a muffle furnace and heat it to 550°C at a rate of 5°C / min, then maintain the temperature for 6 hours.

[0032] b. Add 32.94g norbornene, 13.22g dicyclopentadiene, and 1.32g SAPO-11 molecular sieve to a quartz glass liner, and place it in a 100mL fully automated reactor. The specific apparatus is as follows: Figure 2As shown, after sealing the reactor, pressurize it with nitrogen to 4 MPa and maintain it for 30 minutes to check for leaks. If the pressure remains basically unchanged within 30 minutes, unload the pressure (i.e., the initial pressure is 0 MPa). Repeat this process three times to replace the air in the reactor with nitrogen. Then, raise the temperature to 190°C, set the reaction time to 6.5 hours, adjust the rotation speed to 600 r / min, and start heating to carry out the reaction.

[0033] After the reaction is complete, the product is removed and subjected to chromatographic analysis, which is denoted as Scheme A.

[0034] Comparative Example 1:

[0035] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is removed, while the other conditions remain unchanged, and this is referred to as Scheme B.

[0036] Comparative Example 2:

[0037] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is replaced with SAPO-34 molecular sieve, and the other preparation processes are the same as in Example 1. This is referred to as Scheme C.

[0038] Comparative Example 3:

[0039] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is replaced with Al-MCM-41 molecular sieve, and the other preparation processes are the same as in Example 1. This is referred to as Scheme D.

[0040] Comparative Example 4:

[0041] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is replaced with H-ZSM-5 molecular sieve, and the other preparation processes are the same as in Example 1, which is referred to as Scheme E.

[0042] Example 2:

[0043] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is replaced with HY mesoporous molecular sieve, and the other preparation processes are the same as in Example 1, which is referred to as Scheme F.

[0044] Example 3:

[0045] Compared with Example 1, the SAPO-11 molecular sieve in step 2 is replaced with HY microporous molecular sieve, and the other preparation processes are the same as in Example 1, which is referred to as Scheme G.

[0046] Example 4:

[0047] Compared to Example 1, the SAPO-11 molecular sieve in step 2 was replaced with Hβ microporous molecular sieve, while the other preparation processes were the same as in Example 1. This is referred to as Scheme H.

[0048] Example 5:

[0049] Compared to Example 1, the SAPO-11 molecular sieve in step 2 was replaced with USY molecular sieve, while the other preparation processes were the same as in Example 1. This is referred to as Scheme I.

[0050] Substituting the experimental conditions of the above examples and comparative examples into the actual reaction, the polymerization results of dicyclopentadiene and norbornene were detected by gas chromatography (listed in Table 1).

[0051] Table 1. Effects of different types of molecular sieves on TCD selectivity

[0052]

[0053] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for synthesizing pendant tetracyclic dodecenes via molecular sieve catalytic polymerization, characterized in that, In the polymerization reaction of cyclopentadiene and norbornene, molecular sieves are added as catalysts to improve the selectivity of pedobionic tetracyclododecene in the product. The method includes the following steps: (1) Pretreatment of molecular sieves: The molecular sieve catalyst is calcined; (2) To carry out the polymerization reaction: (21) Add norbornene, dicyclopentadiene and the molecular sieve catalyst pretreated in step (1) to the reactor. After sealing the reactor, check whether the reactor is leaking. After confirming that the reactor is not leaking, proceed to the next step. (22) Replace the air in the reactor with nitrogen, then heat and stir to carry out the reaction, and collect the product after the reaction is completed; In step (1), the calcination temperature is 550 ℃, the calcination time is 6h, the calcination heating rate is 5 ℃ / min, and the molecular sieve is SAPO-11 molecular sieve. In step (21), the mass ratio of norbornene, dicyclopentadiene and molecular sieve catalyst is 20:10:1 to 25:10:

1.

2. The preparation method according to claim 1, characterized in that, In step (21), the method for detecting whether the reactor is leaking is as follows: pressurize with nitrogen to the first pressure and maintain it for the first time. If the pressure does not change during the first time, it means that the reactor is not leaking. Then unload the pressure and return to the initial pressure of 0 MPa. Repeat this process multiple times.

3. The preparation method according to claim 1, characterized in that, In step (22), the reaction temperature is 170-200 °C, the reaction time is 4-10 h, and the stirring speed is 600-700 r / min.

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