CN112250535A - Preparation method of p-cymene - Google Patents

Preparation method of p-cymene Download PDF

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CN112250535A
CN112250535A CN202011285620.6A CN202011285620A CN112250535A CN 112250535 A CN112250535 A CN 112250535A CN 202011285620 A CN202011285620 A CN 202011285620A CN 112250535 A CN112250535 A CN 112250535A
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cymene
catalyst
temperature
tower
turpentine
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CN112250535B (en
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孟中磊
周永红
蒋剑春
胡立红
赵振东
高守娜
廖仲秋
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Guangxi Zhuang Autonomous Region Forestry Research Institute
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/367—Formation of an aromatic six-membered ring from an existing six-membered ring, e.g. dehydrogenation of ethylcyclohexane to ethylbenzene
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/06—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of zinc, cadmium or mercury
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
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    • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
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    • C07—ORGANIC CHEMISTRY
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Abstract

The invention discloses a preparation method of p-cymene, and relates to the technical field of rosin deep processing. Taking the turpentine or a dipentene byproduct generated by hydration and ethyl esterification of the turpentine as a raw material, and heating and reacting under the action of a catalyst to prepare p-cymene; the catalyst comprises one or more of aluminum sulfate, potassium sulfate, alum, zinc powder, aluminum powder and zinc-aluminum alloy powder. The method of the invention can be suitable for preparing the cymene by the dehydrogenation of the dipentene, can also be used for catalyzing the direct isomeric dehydrogenation of the pinene to generate the p-cymene, has wide application of raw materials, and has the GC content of the high boiling point polymer of less than or equal to 17 percent. The catalyst has high selectivity, no corrosion, no toxicity, low cost and mild reaction condition.

Description

Preparation method of p-cymene
Technical Field
The invention relates to the technical field of rosin deep processing, in particular to a preparation method of p-cymene.
Background
P-cymene, p-cymene and 1-methyl-4-isopropyl benzene are colorless transparent oily substances, have specific fragrance, have a boiling point of 176-177 ℃, have a specific gravity of 0.835-0.860, are insoluble in water, and are easily soluble in ethanol, diethyl ether, acetone and liquid paraffin. P-cymene exists in various essential oils, and the effective component of Rhododendron pulchrum of Ericaceae is a medicine for eliminating phlegm, relieving cough and relieving cough.
Paracymene is also an important chemical product and an organic synthesis intermediate with wide application, and can be used in soft drinks, ice food, candies, chewing gums and seasonings; can also be used for synthesizing various polycyclic musk type perfumes (such as muscone umbellate, pink sandalwood, musk tona, etc.), medicines, herbicides, bactericides, etc. Terephthalic acid, which is also prepared from p-cymene, is useful in the manufacture of synthetic resins, synthetic fibers and plasticizers. P-cymene is oxidized and acidolyzed to obtain p-cresol, which is an important raw material for synthesizing fine chemical products such as pesticides, medicines, synthetic materials, spices and the like.
The synthesis method of p-cymene can be divided into two types according to different raw materials, namely a toluene and propylene route and a turpentine route. The former is prepared by passing toluene and propylene (or propanol) through Fried-CrThe afts are obtained by alkylation, which in practice gives a mixture of o-, m-and p-cymene, the cresols obtained from it also being mixed cresols. The selectivity of the synthesis of p-cymene from toluene is poor, while the conditions of the high-selectivity synthesis method are harsh. Turpentine is a rich renewable resource, and the main component of the turpentine is pinene. In the production process of synthesizing camphor and terpineol by using turpentine as raw material, a large quantity of by-products industrial dipentene can be produced, and its main component is several pairs with different double-construction positions
Figure BDA0002782283980000011
Dienes having the same carbon skeleton as p-cymene. Pinene in the turpentine oil is isomerized into dipentene, and then dehydrogenation is carried out to synthesize p-cymene. The preparation of terpineol, terpinyl acetate, bornyl acetate and the like from turpentine through hydration and ethyl esterification is often accompanied by side reactions of isomerizing into dipentene, and the dipentene is difficult to separate and can be used as a raw material for preparing p-cymene.
The catalytic dehydrogenation of dipentene to synthesize p-cymene usually adopts gas phase method and liquid phase method. The gas phase method has already been industrialized abroad, the used dehydrogenation catalyst is mainly the catalyst loading noble metals Pd, R and the like, the yield is more than 80%, but the catalyst used in the process is very expensive, and the production cost is high. The catalyst used in domestic gas phase dehydrogenation mainly comprises CrO3-Al203、Cu-Cr-Al2030.5% Pd-C, etc. Catalysts used in liquid phase reactions have also been reported in the literature, such as 5% Pd impregnated activated carbon, Raney-Ni, nickel formate, copper formate-nickel formate, and the like. The catalyst for preparing p-cymene by dehydrogenating dipentene mainly comprises nickel catalyst and noble metal catalyst. However, the nickel-based catalyst has the disadvantages of high reaction temperature, long reaction time, high requirement on reaction equipment, harsh operation conditions and poor selectivity in the process of catalyzing the dehydrogenation reaction of dipentene. Therefore, research and development of a novel catalyst with excellent activity have important practical significance for realizing the dehydrogenation of the dipentene under mild conditions. Lianghuiming, in its paper "SO4 2-/ZrO2Study on preparation of-MxOy/SBA-15 and catalytic dehydrogenation of dipentene to generate p-cymeneA vacuum impregnation method is adopted, and a plurality of common non-noble metal elements, namely Al, Ni, Cu, Fe and Zn are selected and used for modifying SO4 2-/ZrO2SBA-15 solid acid catalyst to prepare SO4 2-/ZrO2-MxOy/SBA-15(M ═ Al, Ni, Cu, Fe, Zn) novel solid acid catalysts, characterized by BET and n-butylamine potentiometric titration, and investigated the SO of these non-noble metal elements4 2-/ZrO2The influence of the SBA-15 solid acid catalyst and the influence of the modified catalyst on the reaction of catalyzing the preparation of the dipentene on the cymene. Modified by a single non-noble metal, SO4 2-/ZrO2The acid strength of the/SBA-15 solid acid catalyst is obviously enhanced, and SO is modified by binary non-noble metal elements4 2-/ZrO2The acid strength of the/SBA-15 solid acid catalyst was significantly reduced and no strong acid was detected in the catalyst. The activity test result of the catalyst shows that the novel solid acid catalyst modified by non-noble metal, SZr-Zn/SBA-15 solid acid catalyst modified by non-noble metal Zn is beneficial to improving the selectivity of the cymene, and the proper reduction of the load of ZnO in the catalyst and the improvement of the roasting temperature of the catalyst are both beneficial to improving the selectivity of the cymene. When the loading of ZnO in the SZr-Zn/SBA-15 catalyst is reduced by 0.05 percent, the selectivity of the catalyst on the cymene is improved to 36.17 percent.
When the pinene is used for synthesizing the p-cymene, the p-cymene is firstly isomerized into dipentene, and then the dipentene is dehydrogenated to obtain the cymene. Li Hei, a published article "Synthesis of p-cymene from turpentine Synthesis" (Fine chemical, vol. 19, No. 8, 8.2002) discloses the separation of alpha pinene from turpentine oil, at solvent reflux temperature and SiO2-Al2O3-FeSO4Terpinene and limonene are synthesized under the action of the catalyst, and the yield reaches 47% and 43% respectively. Under the catalytic action of Ni-Cu, terpinene and limonene are synthesized into p-cymene by adopting a fixed bed integral reactor, the process conditions are that the temperature is 300-350 ℃, the pressure is 9-11 kPa, the yield of the p-cymene is over 56 percent, and the catalyst effect of the two-step reaction is considered to be good. Wang ai, et al, in the publication of "SO4 2-/ZrO2The research on the preparation of p-cymene by catalyzing alpha-pinene cyclization and isomerization "researches a suitable process for preparing p-cymene by catalyzing alpha-pinene cyclization and isomerization by using self-made solid super acid. In the isomerization part of alpha-pinene, a series of solid super acids are prepared and compared with concentrated sulfuric acid used in industrial production, and the result shows that the catalytic effect of the solid super acids on the preparation of the monocyclic diene by the ring opening isomerization of the alpha-pinene is stronger than that of the concentrated sulfuric acid, wherein SO is used for preparing the monocyclic diene4 2-/ZrO2For optimization, better reaction conditions are determined by a single-factor experiment4 2-/ZrO2The roasting temperature is 650 ℃; the dosage of the catalyst is 1.0 percent of the mass of the alpha-pinene; the reaction time is 4h, and the reaction temperature is 130 ℃; the monocyclodiene content of the product at this point was 56.6%. The catalyst still keeps higher activity after being repeatedly used for 6 times. Simultaneously, the obtained diolefin is catalyzed and disproportionated to prepare p-cymene, and the obtained product is subjected to structural characterization by GC-MS and 1H NMR.
The pinene can also be directly subjected to isomeric dehydrogenation to produce p-cymene. Liangjizhen, et al, in the published paper "reaction process of direct preparation of p-cymene from turpentine on activated clay" disclose that p-cymene is directly prepared by liquid phase method using self-made activated clay as catalyst and turpentine as raw material, and Fourier infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) are adopted to analyze and identify reaction products, study the reaction process and discuss the reaction mechanism. A total of 44 peaks were isolated by GC-MS analysis, and 41 compounds were identified, of which the main products were p-cymene and 3-p-menthene with relative mass fractions of 56.57% and 10.46%, respectively; the conversion rate of pinene which is the main component of turpentine is 100 percent, and the yield of p-cymene is 62.78 percent; the presence of non-volatile materials and polymers such as cembrene in the turpentine disproportionation product was identified. FT-IR analysis showed 3022, 1655cm of the double bond in the pinene ring in the product-1Characteristic peak and ═ CH23067cm-1The characteristic peak basically disappears, 1611, 1498 and 1458cm-1Vibration of benzene ring skeleton and vibration of 815cm-1The intensity of the para-disubstituted singlet of the benzene ring is increased, which also indicates that the pinene has completely reacted and mainly generates p-cymene. The reaction process of catalyzing turpentine by activated clay is exploredThe study shows that isomerization and intermolecular hydrogen transfer disproportionation of bicyclo monoterpene pinene are the main reactions, and accompanied by deep ring opening isomerization, hydration rearrangement, polymerization and other side reactions, sesquiterpene is subjected to isomerization, dehydrogenation, hydration rearrangement and other reactions.
The side product in the production of terpineol from pinene can also synthesize p-cymene. Anxinnan, et al, published in the paper "analysis of chemical composition and utilization of by-products in terpineol production" disclose that the chemical composition of by-products in one-step terpineol production was analyzed by gas chromatography-mass spectrometry (GC-MS), and 22 chemical components were identified in total, the main components being limonene, terpinolene, alpha-pinene, 1, 8-cineole, and the like. Research the by-product in SO production of terpineol4 2-/TiO2-ZrO2The reaction rule under the action of the solid super acidic catalyst analyzes the influence of the factors such as the roasting temperature, the reaction time, the catalyst dosage and the like of the catalyst on the catalytic performance of the catalyst. The influence of the catalyst standing time on the isomerate and the catalyst reuse condition are examined. The result shows that the catalyst has higher catalytic activity on the reaction of the terpineol by-product. Through GC-MS analysis, the main product is p-cymene, and the byproducts are mainly terpinene and alpha-terpinene. Suitable catalyst preparation conditions are a calcination temperature of 3:1, 650 ℃ M (titanium) to M (zirconium). Under the preparation conditions, the suitable process conditions of the byproduct reaction in the terpineol production are that the reaction time is 6 hours, the reaction temperature is 130 ℃, and the catalyst dosage is 3 percent. The p-cymene content of the obtained product was 60.60%.
As described above, the conventional technology for synthesizing p-cymene from turpentine has the main problems that: firstly, the catalyst used for preparing p-cymene by gas-phase dehydrogenation is very expensive and needs dipentene with higher purity; secondly, the yield of the product by the liquid phase method is still to be improved compared with that by the gas phase method, and the preparation of the catalyst is complex; thirdly, pinene is directly used for isomeric dehydrogenation to prepare p-cymene, and the product contains more polymers.
Disclosure of Invention
Aiming at the technical problems in the existing p-cymene production, the invention provides a method for preparing p-cymene by using dipentene byproduct generated by hydration and ethyl esterification of turpentine or turpentine as a raw material, wherein the catalyst has high selectivity, no corrosion, no toxicity, low price and mild reaction conditions.
A preparation method of p-cymene comprises heating and reacting turpentine or dipentene byproduct generated by hydration and ethyl esterification of turpentine as raw material under the action of catalyst to prepare p-cymene; the catalyst comprises one or more of alum, zinc powder, aluminum powder and zinc-aluminum alloy powder.
Pinene → cymene + dipentene + 3-pairs
Figure BDA0002782283980000041
Alkene + polymerization product
Dipentene → cymene + 3-pair
Figure BDA0002782283980000042
Alkene + polymerization product
The byproduct of the hydration and ethyl esterification reaction of turpentine comprises dipentene, cymene, camphene, fenchylene and the like, and if the turpentine alcohol is produced, borneol, fenchyl alcohol and the like. However, borneol, fenchyl alcohol, etc. can be converted into camphene, fenchyl alkene by dehydration, and converted into dipentene by ring opening, etc.
Further, the preparation method of p-cymene comprises the following steps:
(1) adding the raw materials and the catalyst into a reaction kettle according to the mass ratio of 100:1-15, stirring at the speed of 300-;
(2) washing and drying the filtrate obtained in the step (1) to obtain a crude p-cymene product, and carrying out reduced pressure fractionation to obtain the p-cymene product.
Further, the organic solvent is ethanol, ethyl acetate or hexane.
Further, the filter cake in the step (1) is washed by an organic solvent and dried to be used as a raw material for recycling.
Further, water accounting for 1-30% of the mass of the raw materials is added in the step (1).
Further, the vacuum fractionation in the step (2) comprises the following steps:
firstly, reducing the vacuum degree in the rectifying tower to be less than or equal to-0.09 MPa, and then adding a p-cymene crude product;
heating to make the temperature of the tower bottom reach 100 ℃ and 110 ℃, the temperature of the tower top reach 80-90 ℃, refluxing for 1-2h, and collecting front fractions of camphene and dipentene (turpentine is one of the products as the raw material dipentene) according to the reflux ratio of 11-13: 1;
thirdly, raising the temperature to ensure that the temperature of the tower bottom reaches 110-120 ℃, the temperature of the tower top reaches 90-105 ℃, the reflux ratio is 20-23:1, and collecting 3-pairs of middle fractions
Figure BDA0002782283980000051
An alkene;
fourthly, the vacuum degree in the tower is increased to be less than or equal to minus 0.1MPa, the temperature of the bottom of the tower is maintained at 130 ℃ in the temperature range of 120-.
Further, the catalyst consists of aluminum and zinc in a mass ratio of 1: 2-3.
Further, the catalyst consists of alum and aluminum powder in a mass ratio of 1: 0.5-2.
Further, the catalyst consists of alum and zinc powder in a mass ratio of 1: 0.5-1.
Further, the catalyst also contains activated carbon.
Further, the catalyst consists of alum and activated carbon in a mass ratio of 1: 1-2.
Further, the catalyst is prepared by drying alum at the temperature of 150-.
Compared with the prior art, the invention has the advantages and beneficial effects that:
1. the catalyst is prepared by catalyzing the turpentine or dipentene byproducts generated by hydration and ethyl esterification of the turpentine through the catalyst consisting of one or more of alum, zinc powder, aluminum powder and zinc-aluminum alloy powder, and performing isomeric dehydrogenation on the turpentine or the dipentene byproducts.
2. The catalyst used in the invention has simple preparation and higher catalytic activity, and the selectivity of the product cymene can be obviously improved by using the alum as the composite catalyst consisting of the aluminum powder, the zinc powder and the alum.
3. The method can solve the problems of catalyst agglomeration and bonding in the catalytic reaction process and improve the catalytic activity by drying alum alone or together with active carbon at the temperature of 100 ℃ and 200 ℃ and then grinding.
4. The method of the invention can promote the generation of the target product and reduce side reactions by adding a certain amount of water into the reaction system.
5. The pinene often generates polymerization side reaction during the isomerization and dehydrogenation, and a high boiling point polymer which is not easy to separate and purify is generated. The method of the invention can be suitable for preparing the cymene by the dehydrogenation of the dipentene and can also be used for catalyzing the direct isomeric dehydrogenation of the pinene to generate the p-cymene, the raw materials are widely used, and the GC content of the high boiling point polymer is less than or equal to 17 percent.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
The pinene content of the turpentine used in the following examples of the present invention may have a wide range, and the total content of α -pinene and β -pinene GC is indicated in parentheses for the turpentine raw materials. The product components are qualitatively determined by GC-MS and relative content determination according to a general method for determining GBT11538-2006 essential oil capillary column and a specific method for determining LY/T2859-2017 p-cymene; the dried alum is prepared by drying for 3h at the temperature of 200 ℃, cooling to room temperature and grinding. The aluminum powder, the zinc powder and the aluminum-zinc alloy powder are all 100-mesh powder.
Example 1
(1) Adding 80 percent of turpentine, a catalyst and water into a reaction kettle according to the mass ratio of 100:7:25, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 180 ℃ and the reaction time to be 2 hours; the catalyst is alum;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with ethanol to remove residual product, and drying at 150 ℃ for recycling;
(3) adding the filtrate into a water washing tank, adding water, and washing for 2 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000071
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 100 ℃, the temperature of the tower top at 80 ℃, refluxing for 1.5h, and collecting front distillates of camphene and dipentene according to a reflux ratio of 11: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 90 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 20:1
Figure BDA0002782283980000072
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 120 ℃, keeping the temperature of the top of the tower at 110 ℃, and collecting p-cymene products according to the reflux ratio of 13: 1.
In this example, the total conversion of pinene in the raw material turpentine was 100%, the GC content of the obtained p-cymene in the crude p-cymene product was 36%, the GC content of the polymer in the crude product was 15%, and the crude product yield was 78%; the GC content of the product after vacuum fractionation to the cymene is more than or equal to 99.0 percent.
Example 2
(1) Adding 80 percent of turpentine, a catalyst and water into a reaction kettle according to the mass ratio of 100:5:25, starting stirring at the stirring speed of 400rpm, controlling the reaction temperature to be 300 ℃ and the reaction time to be 2 hours; the catalyst is 100-mesh aluminum powder;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with ethanol to remove residual product, and drying at 150 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000073
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 110 ℃, the temperature of the tower top at 90 ℃, refluxing for 2h, and collecting front distillates of camphene and dipentene according to a reflux ratio of 12: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 120 ℃, keeping the temperature of the tower top at 100 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 22:1
Figure BDA0002782283980000081
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 130 ℃, keeping the temperature of the top of the tower at 110 ℃, and collecting p-cymene products according to the reflux ratio of 14: 1.
In this example, the total conversion of pinene in the raw material turpentine is 100%, the GC content of the obtained p-cymene in the crude p-cymene product is 47%, the GC content of the polymer in the crude product is 13%, and the crude product yield is 79%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 3
(1) Adding 80 percent of turpentine, a catalyst and water into a reaction kettle according to the mass ratio of 100:5:25, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 300 ℃, the pressure to be 7-8MPa and the reaction time to be 1-2 h; the catalyst is 100-mesh zinc powder;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, adding water, and washing for 3 times to obtain a crude product containing p-cymene;
(4) will be provided withSubjecting the crude product containing p-cymene to vacuum fractionation to obtain 3-p-cymene
Figure BDA0002782283980000082
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude product containing p-cymene and then conveying the dried crude product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 100 ℃, the temperature of the tower top at 90 ℃, refluxing for 2 hours, and collecting front distillates of camphene and dipentene according to a reflux ratio of 13: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 120 ℃, keeping the temperature of the tower top at 105 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 23:1
Figure BDA0002782283980000083
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 130 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 13: 1.
In the embodiment, the total conversion rate of pinene in the raw material turpentine is 98%, and the GC content of the obtained p-cymene crude product is 45%; the GC content of the polymer in the crude product is 16 percent, and the yield of the crude product is 80 percent; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 4
(1) Adding 80 percent of turpentine and a catalyst into a reaction kettle according to the mass ratio of 100:10, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 350 ℃, the pressure to be 1.5-3.0MPa, and the reaction time to be 3 h; the catalyst is alum and 100-mesh zinc powder, and the mass ratio of the alum to the 100-mesh zinc powder is 1: 1;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000091
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude product of the borneol acetate, and conveying the dried crude product of the borneol acetate to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 105 ℃, the temperature of the tower top at 85 ℃, refluxing for 2 hours, and collecting front distillates of camphene and dipentene according to a reflux ratio of 13: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 115 ℃, keeping the temperature of the tower top at 95 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 22:1
Figure BDA0002782283980000092
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 125 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 15: 1.
In the embodiment, the total conversion rate of pinene in the raw material turpentine is 98%, and the GC content of the obtained p-cymene crude product is 51%; the GC content of the by-product polymer is 12 percent, and the crude product yield is 85 percent; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 5
(1) Adding 80 percent of turpentine and a catalyst into a reaction kettle according to the mass ratio of 100:10, starting stirring at the stirring speed of 300rpm, controlling the reaction temperature to be 350 ℃, the pressure to be 2-2.5MPa, and the reaction time to be 1-3 h; the catalyst is alum and 100-mesh aluminum powder, and the mass ratio of the catalyst to the aluminum powder is 1: 1;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000093
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 100 ℃, the temperature of the tower top at 80 ℃, refluxing for 2 hours, and collecting front distillates of camphene and dipentene according to a reflux ratio of 13: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 120 ℃, keeping the temperature of the tower top at 105 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 20:1
Figure BDA0002782283980000101
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 120 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 13: 1.
In the embodiment, the total conversion rate of pinene in the raw material turpentine is 99%, the GC content of the obtained p-cymene crude product is 48%, the GC content of the byproduct polymer is 17%, and the crude product yield is 85%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 6
A method for preparing p-cymene by using turpentine and reaction byproducts of hydration, ethyl esterification and the like of the turpentine is characterized by comprising the following steps of:
(1) adding dipentene by-product, catalyst and water generated by turpentine hydration and ethyl esterification reaction into a reaction kettle according to the mass ratio of 100:10:1, starting stirring, controlling the stirring speed to be 500rpm, controlling the reaction temperature to be 300 ℃ and the reaction time to be 1-3h under the pressure of 9-10 MPa; the catalyst is alum and 100-mesh aluminum powder, and the mass ratio of the catalyst to the aluminum powder is 1: 0.5;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000102
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 110 ℃, the temperature of the tower top at 90 ℃, refluxing for 2 hours, and collecting the front cut dipentene according to the reflux ratio of 12: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 105 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 23:1
Figure BDA0002782283980000111
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 120 ℃, keeping the temperature of the top of the tower at 110 ℃, and collecting p-cymene products according to the reflux ratio of 13: 1.
In this example, the total conversion of the raw materials was 97%, the GC content of cymene in the obtained p-cymene crude product was 55%, the GC content of the polymer in the crude product was 8%, and the yield of the crude product was 86%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 7
(1) Adding dipentene by-product, catalyst and water generated by turpentine hydration and ethyl esterification reaction into a reaction kettle according to the mass ratio of 100:10:2, starting stirring at the stirring speed of 400rpm, controlling the reaction temperature at 300 ℃, the pressure at 8-9MPa and the reaction time at 3 h; the catalyst is alum and 100-mesh zinc powder, and the mass ratio of the alum to the zinc powder is 1: 0.5;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000112
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 105 ℃, keeping the temperature of the tower top at 90 ℃, refluxing for 2 hours, and collecting the front cut dipentene according to the reflux ratio of 12: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 105 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 23:1
Figure BDA0002782283980000113
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 130 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 14: 1.
In the embodiment, the conversion rate of pinene in the raw material turpentine is 100%, the GC content of p-cymene in the obtained p-cymene crude product is 59%, the GC content of the byproduct polymer is 2%, and the crude product yield is 87%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 8
(1) Adding dipentene by-product, catalyst and water generated by turpentine hydration and ethyl esterification reaction into a reaction kettle according to the mass ratio of 100:15:2, starting stirring at the stirring speed of 300 and 500rpm, controlling the reaction temperature at 300 ℃ and the reaction time at the pressure of 7-8MPa for 1-3 h; the catalyst is dried alum and 100-mesh aluminum powder, and the mass ratio of the catalyst to the aluminum powder is 1: 0.5;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 100 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000121
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude p-cymene product and conveying the dried product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 90 ℃, refluxing for 2 hours, and collecting the front cut dipentene according to the reflux ratio of 13: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 100 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 23:1
Figure BDA0002782283980000122
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 125 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 14: 1.
In the embodiment, the conversion rate of pinene in the raw material turpentine is 97%, the GC content of p-cymene in the obtained p-cymene crude product is 58%, the GC content of a polymer in the crude product is 6%, and the yield of the crude product is 85%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 9
(1) Adding 80 percent of turpentine, a catalyst and water into a reaction kettle according to the mass ratio of 100:10:2, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 300 ℃, the pressure to be 8-9MPa and the reaction time to be 3 h; the catalyst is dried alum, activated carbon and 100-mesh zinc powder, and the mass ratio of the catalyst to the zinc powder is 1:1: 0.5;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000131
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude product containing p-cymene and then conveying the dried crude product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 110 ℃, the temperature of the tower top at 90 ℃, refluxing for 2h, and collecting front distillates of camphene and dipentene according to a reflux ratio of 12: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 110 ℃, keeping the temperature of the tower top at 90 ℃, and collecting the middle distillate 3-pairs with the reflux ratio of 20:1
Figure BDA0002782283980000132
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 120 ℃, keeping the temperature of the top of the tower at 110 ℃, and collecting p-cymene products according to the reflux ratio of 13: 1.
In this example, the total conversion of pinene in the raw material turpentine was 98%, the GC content of p-cymene in the obtained p-cymene crude product was 60%, the GC content of the polymer in the crude product was 2%, and the crude product yield was 84%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
Example 10
(1) Adding 80 percent of turpentine, a catalyst and water into a reaction kettle according to the mass ratio of 100:10:20, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 250 ℃, the pressure to be 6-7MPa and the reaction time to be 1 h; the catalyst is dried alum, activated carbon and zinc-aluminum alloy powder, and the mass ratio of the catalyst to the zinc-aluminum alloy powder is 1:1: 0.3;
(2) after the reaction is finished, filtering the product to obtain filtrate and filter cake, washing the filter cake with organic solvents such as ethanol, ethyl acetate, hexane and the like to remove residual products, and drying at 200 ℃ for recycling;
(3) adding the filtrate into a water washing tank, and washing with water for 3 times to obtain a crude product containing p-cymene;
(4) vacuum fractionating the crude product containing p-cymene to obtain 3-p-cymene
Figure BDA0002782283980000133
Alkene by-products and p-cymene products.
The fractionation in the step (4) is vacuum fractionation, and the specific operation is as follows:
s1, firstly discharging air in the rectifying tower to ensure that the vacuum degree in the rectifying tower is less than or equal to-0.09 MPa;
s2, drying the crude product containing p-cymene and then conveying the dried crude product to the bottom of a rectifying tower;
s3, heating to keep the temperature of the tower bottom at 110 ℃, the temperature of the tower top at 85 ℃, refluxing for 2h, and collecting front distillates of camphene and dipentene according to a reflux ratio of 13: 1;
s4, raising the temperature to keep the temperature of the tower bottom at 120 ℃, the temperature of the tower top at 105 ℃, and the reflux ratio of 23:1Collecting the middle fraction 3-pairs
Figure BDA0002782283980000142
An alkene;
s5, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 130 ℃, keeping the temperature of the top of the tower at 115 ℃, and collecting p-cymene products according to the reflux ratio of 15: 1.
S6, increasing the vacuum degree in the tower to be less than or equal to-0.1 MPa, keeping the temperature of the bottom of the tower at 155 ℃, keeping the temperature of the top of the tower at 120 ℃, and collecting the product at the top of the tower, namely the borneol acetate, according to the reflux ratio of 15: 1.
In the embodiment, the conversion rate of pinene in the raw material turpentine is 100%, the GC content of the obtained p-cymene crude product is 65%, the GC content of the polymer in the crude product is 3%, and the yield of the crude product is 85%; the GC content of p-cymene after reduced pressure fractionation is more than or equal to 99.0 percent.
The experimental parametric data for examples 1-10 are summarized in table 1; the experimental results are shown in table 2;
TABLE 1
Figure BDA0002782283980000141
Figure BDA0002782283980000151
TABLE 2
Figure BDA0002782283980000152
Comparative experiment 1
Blank test without adding catalyst;
adding 80% of turpentine into a reaction kettle, starting stirring at the speed of 500rpm, controlling the reaction temperature to be 300 ℃ and the reaction time to be 3 h. In this example, the pinene conversion was about 40%, and the product composition was 9% p-cymene and 30% dipentene.
Comparative experiment 2
The test with activated clay in the technical background;
adding 80 percent of turpentine and activated clay into a reaction kettle according to the mass ratio of 20:1, starting stirring, controlling the stirring speed to be 500rpm, controlling the reaction temperature to be 300 ℃, and controlling the reaction time to be 3 hours. In this example, the product composition was 2.8% of 3-pairs
Figure BDA0002782283980000161
Alkene, 25.1% p-cymene, 1.5% longifolene, 2.6% 7-tert-butyl-A-tetralone, 51.7% polymer.
Comparative experiment 3
The combination experiment of the activated clay in the technical background and the catalyst of the invention is carried out;
adding 80 percent of turpentine, activated clay and alum into a reaction kettle according to the mass ratio of 30:1:1, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 200 ℃ and the reaction time to be 1-3 h. In this example, the product composition was 5.7% of 3-pairs
Figure BDA0002782283980000162
Alkene, 27.2% p-cymene, 54.8% polymer.
Comparative experiment 4
The combination experiment of the activated clay in the technical background and the catalyst of the invention is carried out;
adding 80 percent of turpentine, activated clay and aluminum powder into a reaction kettle according to the mass ratio of 30:1:0.7, starting stirring at the stirring speed of 500rpm, controlling the reaction temperature to be 200 ℃ and the reaction time to be 1-3 h. In this example, the product composition was 3.7% of 3-pairs
Figure BDA0002782283980000163
Alkene, 24.6% p-cymene, 57.4% polymer.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A preparation method of p-cymene is characterized in that turpentine or a dipentene byproduct generated by hydration and ethyl esterification of turpentine is used as a raw material, and p-cymene is prepared by heating reaction under the action of a catalyst; the catalyst comprises one or more of alum, zinc powder, aluminum powder and zinc-aluminum alloy powder.
2. The method for preparing p-cymene according to claim 1, characterized by comprising the steps of:
(1) adding the raw materials and the catalyst into a reaction kettle according to the mass ratio of 100:1-15, stirring at the speed of 300-;
(2) washing and drying the filtrate obtained in the step (1) to obtain a crude p-cymene product, and carrying out reduced pressure fractionation to obtain the p-cymene product.
3. The method for preparing p-cymene according to claim 2, characterized in that the filter cake in step (1) is washed with organic solvent and dried, and then is reused as raw material.
4. The method for preparing p-cymene according to claim 2, characterized in that water is added in the amount of 1-30% by mass of the raw material in step (1).
5. The process for the preparation of p-cymene according to claim 2, characterized in that said fractional distillation under reduced pressure in step (2) comprises the following steps:
firstly, reducing the vacuum degree in the rectifying tower to be less than or equal to-0.09 MPa, and then adding a p-cymene crude product;
heating the tower kettle to 100 ℃ and 110 ℃, refluxing the tower top to 80-90 ℃ for 1-2h, and collecting front fractions of camphene and dipentene according to a reflux ratio of 11-13: 1;
thirdly, raising the temperature to ensure that the temperature of the tower bottom reaches 110-120 ℃, the temperature of the tower top reaches 90-105 ℃, the reflux ratio is 20-23:1, and collecting 3-pairs of middle fractions
Figure FDA0002782283970000011
An alkene;
fourthly, the vacuum degree in the tower is increased to be less than or equal to minus 0.1MPa, the temperature of the bottom of the tower is maintained at 130 ℃ in the temperature range of 120-.
6. A process for preparing p-cymene according to any one of claims 1 to 5, characterized in that said catalyst consists of aluminum and zinc in a mass ratio of 1:2 to 3.
7. The process for producing p-cymene according to any one of claims 1 to 5, wherein said catalyst consists of alum and aluminum powder in a mass ratio of 1: 0.5-2.
8. The process for preparing p-cymene according to any one of claims 1 to 5, characterized in that said catalyst consists of alum and zinc powder in a mass ratio of 1: 0.5-1.
9. A process for the preparation of p-cymene according to any one of claims 1 to 5, characterized in that said catalyst also contains activated carbon.
10. The method for preparing p-cymene according to claim 9, characterized in that said catalyst consists of alum and activated carbon in a mass ratio of 1: 1-2.
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