Method for preparing cyclopentadiene by cracking polydicyclopentadiene
By mixing polydicyclopentadiene powder with molybdenum pentachloride, methylselenodexosugar and p-tert-butylphenol, combined with the combination of molybdenum catalyst and selenium ether, the yield and economy of cyclopentadiene were successfully improved. The added value solves the carbon emission and economic benefits problems in waste polydicyclopentadiene treatment.
Patent Information
- Application Number
- CN202411342556.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2025-01-07
AI Technical Summary
The treatment of waste polycyclopentadiene materials mainly relies on incineration methods, resulting in low carbon emissions and economic benefits, and lack of efficient resource recycling methods.
Polybicyclopentadiene powder, molybdenum pentachloride, methylselenium glucose and p-tert-butylphenol were mixed and heated in a specific proportion, and the volatile fractions were collected in a condensation manner, and cyclopentadiene was purified by distillation, using a molybdenum catalyst and Selenium ether combination improves cleavage activity.
It increases the yield and economic added value of cyclopentadiene, reduces carbon emissions, simplifies the process, and converts waste polydicyclopentadiene into high-value chemicals.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of chemical production, in particular to a method for preparing cyclopentadiene by cracking waste polydicyclopentadiene materials, so as to recycle resources. Background Art
[0002] Polydicyclopentadiene is an engineering plastic with a cross-linked three-dimensional network structure. It is widely used in the manufacture of automotive parts, drone fuselage materials, medical instrument housings, sports equipment housings and other fields. The material has the advantages of easy processing, light weight, high mechanical strength and corrosion resistance, and is widely used. Among them, the amount used in the automotive industry is particularly large. The treatment of waste polydicyclopentadiene materials is an urgent problem to be solved after its large-scale application. At present, the waste material is mainly treated by incineration. Although the incineration of waste polydicyclopentadiene materials to generate electricity can bring certain economic effects, it will also lead to a large amount of carbon emissions, and the benefits are not high. Increasing the economic added value of the treatment of waste polydicyclopentadiene materials and reducing emissions is an industrial problem that needs to be solved urgently. Summary of the invention
[0003] The object of the present invention is to provide a method for preparing cyclopentadiene by cracking polydicyclopentadiene, which can convert polydicyclopentadiene recycled material into cyclopentadiene, thereby improving the economic benefits in the material recycling process and reducing carbon emissions, which is helpful to solve the problem of waste material treatment in the industry.
[0004] In order to solve the above technical problems, the technical solution provided by the present invention is: a method for preparing cyclopentadiene by cracking polydicyclopentadiene, the steps of which are to mix polydicyclopentadiene powder, molybdenum pentachloride, methylselenoglucose and p-tert-butylphenol in a mass ratio of 100:(0.2-2):(1-10):(5-15) and heat to 500-600°C, condense and collect volatile fractions, and then purify by distillation to obtain cyclopentadiene.
[0005] In the present invention, molybdenum pentachloride provides catalytic metal molybdenum, and its usage is 0.2-2.0% of the mass of polydicyclopentadiene powder, preferably 1.0%. This amount of molybdenum catalyst is just suitable for cracking reaction. Too little catalyst will reduce catalytic efficiency, resulting in a decrease in cyclopentadiene yield, while too much catalyst will cause agglomeration, so that part of the catalyst metal cannot be fully utilized.
[0006] In the present invention, the mass content of selenium in methyl selenoglucose is 5-8%, preferably 6.6%, and the amount of methyl selenoglucose used is 1-10% of the mass of polydicyclopentadiene powder, preferably 6%. Methyl selenoglucose can decompose and release methyl selenyl compounds at high temperatures. The compound can replace the hydroxyl group on the phenolic ligand to form selenoether. The coordination of selenoether with molybdenum can significantly improve its catalytic cracking activity. It is worth mentioning that the methyl group is connected to the selenium element, which is the key to the selenium source material. The methyl group can not only improve the stability of the selenium species and prevent it from decomposing into elemental selenium, but also avoid the phenomenon that the substituent steric hindrance is too large and cannot be well coordinated with the metal. If the amount of methyl selenoglucose used is too low, the selenium ligand cannot be produced well, thereby reducing the catalyst activity. On the contrary, if the amount of methyl selenoglucose used is too high, the catalyst will be poisoned by selenium and inactivated, which may be related to the large amount of selenium stacked on the catalyst metal to occupy the coordination orbit.
[0007] In the present invention, the amount of p-tert-butylphenol is 5-15% of the mass of polydicyclopentadiene powder, preferably 10%. Phenols and their selenized products can coordinate with metal platinum to improve catalyst activity. Among them, p-tert-butylphenol is found to be the best ligand / ligand precursor. The main reason is that the electron donation of the tert-butyl group can increase the metal electron cloud density and improve the activity, while its large steric hindrance can avoid the association deactivation of multiple catalyst systems. If the amount of p-tert-butylphenol is not enough, sufficient active catalytic centers cannot be formed, thereby reducing the yield of cyclopentadiene, but if the amount is too much, it will also poison the catalyst, and its principle is the same as the catalyst deactivation caused by excessive use of selenium species.
[0008] In the present invention, the reaction cracking temperature is 500-600°C, preferably 550°C. Polymer cracking involves the breaking of chemical bonds, which requires energy consumption. Studies have found that cracking reactions only occur when the temperature reaches above 500°C. The yield of cyclopentadiene is highest when cracking at 550°C. Too high a reaction temperature will lead to catalyst deactivation on the one hand, and rapid carbonization of the material on the other hand, resulting in a decrease in the yield of cyclopentadiene.
[0009] Compared with the prior art, the present invention has the following beneficial effects:
[0010] 1. The catalyst system is simple and all materials can be easily prepared or purchased directly.
[0011] 2. The reaction process is simple. The cleavage reaction is a simple "one-pot" process that does not require complicated operations.
[0012] 3. The economic added value of the reaction product is high, which is enough to make up for the expenses in the process of recycling polydicyclopentadiene waste and generate profits.
[0013] The prepared cyclopentadiene is a highly chemically active alicyclic hydrocarbon with a wide range of uses. It is not only an important raw material for industries such as pesticides, medicines, rubber, and plastics, but also has important applications in multiple fields such as petroleum resins, coatings, and preservatives. The present invention converts waste polydicyclopentadiene recycled materials into cyclopentadiene with high economic value, thereby increasing the economic benefits of the material recycling process and reducing carbon emissions, which helps to solve the problem of waste material treatment in the industry. DETAILED DESCRIPTION
[0014] The following examples illustrate the present invention in more detail but are not intended to further limit the present invention.
[0015] The molybdenum pentachloride (CAS No.: 10241-05-1) used in this experiment was purchased from Anaiji Chemical with a purity of not less than 98%. The p-tert-butylphenol (CAS No.: 98-54-4) was purchased from Anaiji Chemical with a purity of 98%.
[0016] Methylselenized Glucose with a selenium mass content of 6.6% was synthesized according to the method reported in the literature (Ind.Eng.Chem.Res.2021,60,8659-8663). Generally, the selenium content of the synthesized products is higher than 6.6%, and the selenium content can be adjusted to 6.6% by adding a calculated amount of glucose thereto. By changing the substituents of the Grignard reagent used in the synthesis, other similar substituted glucoses such as ethylselenoglucose can be synthesized. Selenoglucose without hydrocarbon substitution can also be synthesized by the method reported in the literature (Ind.Eng.Chem.Res.2020,59,10763-10767). These selenoglucose analogs were used for comparison in experiments.
[0017] Example 1
[0018] 1 kg of polydicyclopentadiene recycled material powder (referred to as "recycled material"), 10 g of molybdenum pentachloride, 60 g of methylselenoglucose with a selenium content of 6.6%, and 100 g of p-tert-butylphenol were mixed and added to a 5L stainless steel reactor. A simple distillation apparatus (1L capacity) and a spherical condenser were connected to the reactor (see document Appl. Catal. A-Gen. 2017, 541, 107-111). The top of the condenser was connected to the Schlenk double-row tube system, vacuumed and filled with nitrogen, and repeated three times to replace the air therein. Condensed water was filled into the spherical condenser, and the reactor was heated and stirred while being kept in a nitrogen-filled state. About 10 minutes after the heating temperature was raised to 550°C, distillates began to be produced. This process lasted for about 2 hours, and heating was stopped when no new distillates were produced in the simple distillation apparatus. Stop filling with nitrogen after the reaction system has cooled to room temperature. The distillate in the simple distillation device was collected and weighed to obtain 320 grams of light yellow liquid. Gas chromatography analysis showed that the cyclopentadiene content was above 90%. By distilling the liquid, 285 grams of cyclopentadiene with a purity of more than 99% and a yield of 28.5% can be further purified. The carbide remaining in the reactor contains metallic molybdenum and selenium. The carbide material can also be further used in the development of environmentally friendly molybdenum catalyst materials.
[0019] Cyclopentadiene was prepared by cracking polydicyclopentadiene recycled materials with different crosslinking degrees. The results are shown in Table 1:
[0020] Table 1 Comparison of the effects of different polydicyclopentadiene recycled materials on the production of cyclopentadiene by cracking
[0021] serial number Crosslinking degree of polydicyclopentadiene recycled material Cyclopentadiene yield (%) 1 30％ 28.5 2 40％ 28.9 3 50％ 29.0 4 60％ 28.2 5 70％ 28.7
[0022] As shown in Table 1 above, the crosslinking degree of polydicyclopentadiene recycled material has little effect on the production of cyclopentadiene by cracking. This is because the material has already liquefied at high temperature, and the cracking process is essentially a metal-catalyzed olefin metathesis reaction in dicyclopentadiene. After the material is fully liquefied, this chemical process has little to do with the original properties of the material and is only related to the catalyst performance.
[0023] Example 2
[0024] The other conditions were the same as in Example 1, and the reaction effects were tested at different molybdenum pentachloride dosages. The results are shown in Table 2.
[0025] Table 2 Effect of different amounts of molybdenum pentachloride on the reaction.
[0026]
[0027]
[0028] As shown in Table 2, when the amount of molybdenum pentachloride is 0.2% of the mass of the polydicyclopentadiene powder, the cyclopentadiene yield rises to more than 10%, and when the amount of molybdenum pentachloride is 1.0% of the mass of the polydicyclopentadiene powder, the cyclopentadiene yield is 28.5%, which is the optimum value. When the amount of molybdenum pentachloride is increased by more than 2.2%, the cyclopentadiene yield does not change significantly. Taking all factors into consideration, it is advisable that the amount of molybdenum pentachloride is 0.2-2.0% of the mass of the polydicyclopentadiene powder.
[0029] Example 3
[0030] The other conditions were the same as those in Example 1. The effects of different selenium sources on the reaction were tested. The experimental results are shown in Table 3.
[0031]
[0032] It can be seen from Table 3 above that using methylselenoglucose as a selenium source has the best effect.
[0033] Example 4
[0034] The other conditions were the same as those in Example 1, and the effects of different amounts of methylselenoglucose on the cleavage reaction were tested. The experimental results are shown in Table 4.
[0035] Table 4 Effect of methylselenoglucose dosage on cleavage reaction
[0036]
[0037] It can be seen from Table 4 that the best effect is achieved when the dosage of methylselenoglucose is 6%.
[0038] Example 5
[0039] The other conditions were the same as those in Example 1, and the effects of different phenolic ligands on the reaction were tested. The experimental results are shown in Table 5.
[0040] Table 5 Effect of different phenol ligands on the reaction
[0041] serial number Phenolic ligands Cyclopentadiene yield (%) 1 p-tert-Butylphenol (Example 1) 28.5 2 phenol 0 3 p-Toluene 19.2 4 p-Methoxyphenol 14.4 5 3,5-Di-tert-butylphenol 0
[0042] It can be seen from Table 5 that the best effect is achieved when p-tert-butylphenol is used as the phenol ligand.
[0043] Example 6
[0044] The other conditions were the same as those in Example 1, and the effects of different amounts of p-tert-butylphenol on the reaction were tested. The experimental results are shown in Table 6.
[0045] Table 6 Effect of different dosages of tert-butylphenol on the reaction
[0046] serial number Amount of tert-butylphenol (ratio to recycled material mass) Cyclopentadiene yield (%) 1 0 0 2 3％ 4.5 3 5％ 15.6 4 7％ 22.0 5 9％ 26.6 6 10% (Example 1) 28.5 7 11 27.4 8 13％ 20.1 9 15％ 12.5 10 17％ 5.7 11 20％ 0
[0047] It can be seen from Table 6 above that the best effect is achieved when the dosage of p-tert-butylphenol is 10% of the recycled material.
[0048] Example 7
[0049] The other conditions were the same as in Example 1, and the effect of different pyrolysis temperatures on the reaction was tested. The experimental results are shown in Table 7.
[0050] Table 7 Effect of different pyrolysis temperatures on the reaction
[0051] serial number Cracking temperature (℃) Cyclopentadiene yield (%) 1 450 0 2 480 0 3 500 6.6 4 520 20.1 5 540 26.7 6 550 (Example 1) 28.5 7 560 28.0 8 580 22.1 9 600 12.5 10 620 0
[0052] It can be seen from Table 7 that the best cracking effect is achieved when the cracking temperature is 550°C.
[0053] Example 8
[0054] The other conditions were the same as those in Example 1, and the effects of methylselenoglucose with different selenium contents on the reaction were tested. The experimental results are shown in Table 8.
[0055] Table 8 Effect of selenium content on the reaction of methylselenoglucose
[0056] serial number Selenium content wt% methylselenoglucose Cyclopentadiene yield (%) 1 0 0 2 3％ 15.7 3 5％ 22.8 4 6.6 (Example 1) 28.5 5 8％ 27.6 6 12％ 5.4
[0057] The above table shows that the mass content of selenium in methylselenoglucose is 5-8%, preferably 6.6%, and the use of methylselenoglucose with a mass content of 6.6% has the best effect. An increase in the mass content of selenium will lead to excess selenium, which will cause the catalyst to become poisoned and ineffective.
[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.
Claims
1. A method for preparing cyclopentadiene by cracking polydicyclopentadiene, characterized in that: Polydicyclopentadiene powder, molybdenum pentachloride, methylselenoglucose and p-tert-butylphenol are mixed in a mass ratio of 100: (0.2-2): (1-10): (5-15) and heated to 500-600° C. The volatile fraction is condensed and collected, and then purified by distillation to obtain cyclopentadiene.
2. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to claim 1, characterized in that: The mass content of selenium in the methylselenoglucose is 5-8%.
3. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to claim 2, characterized in that: The mass content of selenium in the methylselenoglucose is 6.6%.
4. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to claim 1, characterized in that: The amount of molybdenum pentachloride used is 1.0% of the mass of the polydicyclopentadiene powder.
5. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to claim 1, characterized in that: The dosage of methylselenoglucose is 6% of the mass of polydicyclopentadiene powder.
6. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to claim 1, characterized in that: The amount of p-tert-butylphenol used is 10% of the mass of the polydicyclopentadiene powder.
7. The method for preparing cyclopentadiene by cracking polydicyclopentadiene according to any one of claims 1 to 6, characterized in that: The reaction cracking temperature is 550°C.