A kind of preparation process of pinacolone

Abstract

The present invention provides a process for preparing pinacolone, wherein the reaction raw materials of the process include isopentene, hydrochloric acid and formaldehyde, and the catalyst used is composed of ferric chloride, cupric chloride and lanthanide Lewis acid. The present invention is a continuous reaction process for preparing pinacolone using isopentene, hydrochloric acid and methanol as raw materials, and the intermediate chloro-tert-pentane is condensed to prepare pinacolone by using a catalyst composed of ferric chloride, cupric chloride and lanthanide Lewis acid, which can not only significantly reduce the generation of tar to simplify the post-processing process, but also greatly increase the number of acid water recycling and reduce waste acid discharge; the present invention does not require intermediate separation and purification, and after the reaction is completed, a high-purity pinacolone product can be obtained with high yield only by static stratification and one-time distillation of the upper organic phase; the present invention has a simple process flow and low operation difficulty, and is a green, environmentally friendly and highly economical pinacolone preparation process.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a process for preparing pinacolone. Background Art

[0002] Pinacolone, also known as 3,3-dimethyl-2-butanone, tert-butyl ketone, methyl tert-butyl ketone, etc., is a very important organic fine chemical intermediate, mainly used in the synthesis of fine chemicals such as pesticides, medicines, rubber, dyes and bio-inhibitors. With the continuous deepening of the application research of pinacolone, the demand for high-quality pinacolone in the domestic and foreign markets is increasing. However, the current synthesis methods of pinacolone mostly use isopentene as the raw material, and after the addition reaction of isopentene with hydrochloric acid, it reacts with formaldehyde through cyclization, ring opening, rearrangement and other reactions to finally generate pinacolone.

[0003] The traditional pinacolone production process produces about 19.75% tar, which not only affects the stratification effect, but also generates a large amount of black waste acid that is difficult to handle when dissolved in hydrochloric acid. In the existing pinacolone preparation process, about 5 tons of waste acid will be produced as a by-product for every 1 ton of pinacolone produced. Such a large amount of waste acid can neither be recycled nor directly discharged. The treatment of these waste acids will increase the process operation cost and cause environmental pollution.

[0004] Chinese patent CN103240094A uses tert-pentyl chloride as raw material, and uses Zn / Co / Sb composite catalyst to catalyze the condensation reaction of tert-pentyl chloride and formaldehyde to prepare pinacolone; it is worth noting that the process does not fundamentally solve the problem of byproduct tar, and the subsequent waste acid treatment problem is not solved; in addition, the patent uses tert-pentyl chloride, which is relatively expensive compared to isopentene, as raw material, which increases the process cost, and the subsequent extraction of the intermediate tert-pentyl chloride will increase the workload; in addition, the parameter control of the patent is not accurate and comprehensive enough, which is not conducive to large-scale industrialization. Chinese patent CN105503550A uses isopentene, hydrochloric acid and methanol as raw materials to prepare pinacolone, but the process is an intermittent process, and the intermediate product generated by the first step reaction needs to be extracted before the second step reaction. Although the process solves the problem of waste acid, it cannot avoid the tar problem, which further restricts the scale-up production. Therefore, the process cannot meet the increasing demand for pinacolone in the current market, and is not conducive to industrial production. Chinese patent CN113956142A discloses a method for preparing pinacolone, which uses a single or compound lanthanide Lewis acid as a catalyst to control the tar production amount to 4%-12%. In industrial production, this preparation method still needs to be improved and enhanced. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention discloses a process for preparing pinacolone. The process uses isopentene, hydrochloric acid and formaldehyde as raw materials to prepare pinacolone through a continuous reaction, can realize the recycling of acid water (hydrochloric acid) for 60-80 times and reduce the amount of tar generated, has simplified process steps and strong operability, is a green and environmentally friendly process for preparing pinacolone, and is suitable for industrial production.

[0006] In order to achieve the above technical objectives, the present invention provides a process for preparing pinacolone, wherein the reaction raw materials of the process include isopentene, hydrochloric acid and formaldehyde, and the catalyst used is composed of ferric chloride, cupric chloride and lanthanide Lewis acid.

[0007] In order to solve the problem of acid water recycling in the prior art, the research and development team of the present invention conducted a large number of exploratory experiments, and unexpectedly found that the use of ferric chloride and cupric chloride combined with lanthanum Lewis acid as a catalyst can significantly increase the number of acid water recycling, while the tar generation is also reduced simultaneously. The exploration examples in the specific implementation examples illustrate the exploration process. Based on this discovery, the technical solution of the present invention is proposed, and the embodiment shows the effect of the pinacolone preparation process of the present invention.

[0008] In a further example of the present invention, the type of the lanthanide Lewis acid is explored. Optionally, the lanthanide Lewis acid includes one or both of lanthanum chloride and neodymium chloride.

[0009] In a further example of the present invention, the ratio of the ferric chloride, cupric chloride and lanthanide Lewis acid is explored and optimized. Optionally, the molar ratio of the ferric chloride, cupric chloride and lanthanide Lewis acid is (1-3):(1-2):(1-3), preferably 2:1:1 or 1:1:3. The present invention explores and illustrates the effect of the catalyst pinacolone preparation process with different ratios of ferric chloride, cupric chloride and lanthanide Lewis acid.

[0010] In a further example of the present invention, the amount of ferric chloride, cupric chloride and lanthanide Lewis acid in the catalyst is explored and optimized. Optionally, the sum of the molar amounts of ferric chloride, cupric chloride and lanthanide Lewis acid in the catalyst accounts for 1%-13% of the molar amount of isopentene, further optionally 4%-13%, further optionally 4%-9%, and further optionally 4%. The present invention explores and illustrates the exploration and optimization process.

[0011] In a further example of the present invention, the type and concentration of the hydrochloric acid are optimized. Optionally, the hydrochloric acid is industrial hydrochloric acid, thereby improving the operability of the process of the present invention and reducing production costs; the concentration of the hydrochloric acid can be selected to be 20wt%-35wt%, further 25wt%-30wt%, and further 30wt%.

[0012] In a further example of the present invention, in order to reduce the enrichment of the catalyst in the acid water, the research and development team used a mixed solution containing ferric chloride, cupric chloride and lanthanide Lewis acid to impregnate the carrier, dried it and obtained a supported catalyst, and then put the catalyst into the pinacolone preparation reaction. Figure 1 The flowchart of the pinacolone preparation process is shown. By using a supported catalyst, the catalyst type and the physical form of the catalyst are synergistically optimized, the tar generation of the reaction is reduced to 2.35%, and the number of acid water recycling times is increased to 80 times, thereby greatly reducing the tar generation and process waste acid emissions; in addition, the separated supported catalyst can be recycled, reducing process costs and operating difficulties.

[0013] It should be noted that the present invention does not limit the specific operations of impregnating and drying the mixed solution and the carrier, and may optionally include the following steps: ① dissolving the ferric chloride, copper chloride and lanthanide Lewis acid in water to obtain a mixed solution; ② adding the carrier to the mixed solution for impregnation; further optionally, the step ② includes heating to 95-105°C and stirring to immerse the catalyst in the carrier; ③ taking out the impregnated carrier and continuing to dry; further optionally, the drying temperature of the step ③ is 220-280°C, and the drying time is 5-8h, and the loaded catalyst is obtained for standby use. It should be noted that the loaded catalyst can be recycled.

[0014] In a further example of the present invention, the types of catalyst carriers are explored. Optionally, the carrier includes at least one of inert alumina ceramic balls, silicon dioxide, activated carbon, and molecular sieves; preferably at least one of inert alumina ceramic balls and molecular sieves; the embodiment of the present invention shows the exploration process.

[0015] In a further example of the present invention, the process of the present invention includes a first step: reacting isopentene with hydrochloric acid, in which the raw material isopentene and hydrochloric acid are subjected to an addition reaction to obtain tert-pentyl chloride, an important intermediate for preparing pinacolone; a second step: adding a catalyst and formaldehyde to the material obtained in the first step for reaction, in which tert-pentyl chloride and formaldehyde undergo a condensation reaction to obtain pinacolone, and the reaction route is as follows:

[0016]

[0017] In the process of the present invention, the two-step reaction is a continuous reaction, that is, after the first step reaction is completed, no extraction and separation operations are required, and the material obtained in the first step can be directly fed into the second step reaction, thereby simplifying the process flow and reducing the difficulty of industrial operation.

[0018] In a further example of the present invention, the addition method and physical form of formaldehyde in the first step reaction are explored. Optionally, formaldehyde is added dropwise; the formaldehyde is a formaldehyde aqueous solution or a solid formaldehyde hydrochloric acid solution. Optionally, when a solid formaldehyde salt solution is used, the mass ratio of hydrochloric acid to formaldehyde in the solid formaldehyde hydrochloric acid solution is (2-5):1, preferably (3.75-5):1, and more preferably 3.75:1.

[0019] In a further example of the present invention, the control conditions of the first step and the second step are explored and optimized. Optionally, the reaction temperature in the first step is 0-10°C, preferably 0-5°C, and the reaction time is 50-80 minutes; the reaction temperature in the second step is 60-90°C, and the reaction time is 1-6 hours.

[0020] In a further example of the present invention, the post-treatment of the second step reaction is optimized. Optionally, the material after the second step reaction is cooled to room temperature and allowed to stand for stratification, and the upper layer obtains the pinacolone product, and the lower layer of hydrochloric acid can be recycled. In the technical solution of the present invention, the material after the second step reaction can be optionally cooled to room temperature and allowed to stand for stratification during post-treatment, and the upper organic phase is collected, and the upper organic phase is the crude pinacolone. Since the present invention uses a specific catalyst to catalyze the second step reaction, the tar content in the reacted material is low, and the tar can be further removed from the organic phase only by separating the upper and lower layers after standing; the organic phase is then distilled once to obtain a high-quality pinacolone product. The technical solution of the present invention greatly simplifies the process flow and operation difficulty, and is suitable for industrial production.

[0021] Optionally, the lower layer of hydrochloric acid is extracted with an organic solvent to further remove impurities, and then the organic solvent is added to reach a certain concentration and then recycled. The organic solvent used for extraction can be at least one of ethyl acetate, dichloromethane, and dichloroethane.

[0022] Compared with the prior art, the present invention discloses a continuous reaction process for preparing pinacolone by using isopentene, hydrochloric acid and methanol as raw materials. In the process, a catalyst composed of ferric chloride, cupric chloride and lanthanide Lewis acid is used to catalyze the condensation of an intermediate chloro-tert-pentane to obtain pinacolone, which can not only significantly reduce the generation of tar to simplify the post-treatment process flow, but also greatly increase the number of acid water recycling times and reduce waste acid discharge. The present invention does not require intermediate separation and purification, and after the reaction is completed, a high-purity pinacolone product can be obtained with high yield only by standing for stratification and one-time distillation of the upper organic phase. The overall process flow of the present invention is simple and the operation difficulty is low, and the invention is a green, environmentally friendly and economically efficient pinacolone preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 A flow chart showing a process for preparing pinacolone according to the present invention is shown;

[0025] Figure 2 The gas chromatogram of pinacolone prepared in Example 1 is shown. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0028] Sources of reagents in the following examples:

[0029] Isoamylene: Zibo Liantan Chemical Co., Ltd.

[0030] Solid formaldehyde: Zibo Qixing Chemical Technology Co., Ltd.

[0031] Catalyst: Shandong Desheng New Materials Co., Ltd.

[0032] Catalyst carrier: Pingxiang Dongchen Environmental Protection Chemical

[0033] The method for determining the amount of tar produced in the embodiment of the present invention is as follows: the liquid after the reaction is completed is filtered, centrifuged, and the tar impurities are weighed.

[0034] The number of times of recycling of the acid water in the embodiment of the present invention is determined by the following method: after the preparation of pinacolone is completed, a small sample of the acid water is collected, and 1) the color of the acid water is observed. If the color is clear and transparent, it can be recycled, and if the color is turbid, opaque, and there are visible impurities, it cannot be recycled; 2) the HCl content in the small sample is detected, and an appropriate amount of HCl is added to make the acid liquid meet the concentration of recycling; 3) a small-scale test experiment for preparing pinacolone is carried out using the small sample. When the purity of the prepared pinacolone is not less than 99.99%, the acid water can be recycled, and if the purity of the prepared pinacolone is less than 99.99%, the acid water cannot be recycled.

[0035] The present invention will be further described below in conjunction with exploratory examples and embodiments.

[0036] Explore Example

[0037] A process for preparing pinacolone, specifically, 600kg of 30% industrial hydrochloric acid is added into a reaction kettle, the temperature is lowered to 0-10°C, 190kg of isopentene precooled to -5°C is slowly dripped into the reaction kettle under stirring conditions, and the temperature is controlled at 0-10°C for reaction for 50-80 minutes; then the temperature is raised to 60°C, 21.9kg of ferric chloride catalyst is added in batches, 160kg of hydrochloric acid solution of solid formaldehyde is slowly dripped after stirring and dissolving, the temperature is raised to 70°C for reaction for 3 hours; after the reaction is completed, the reaction is cooled to room temperature and allowed to stand for stratification; the upper organic phase is subjected to a rectification to obtain 231.5kg of colorless transparent liquid pinacolone with a purity of 98.7% and a yield of 85.3%; the lower hydrochloric acid layer is extracted with ethyl acetate organic solvent, the acid water is supplemented with hydrogen chloride and then recycled for 42 times, and the amount of tar produced is 8.25.

[0038] Furthermore, the research and development team of the present invention explored the effects of the pinacolone preparation process on product purity, yield, tar production, and acid water recycling times when other parameters and control conditions were the same and only the catalyst type and composition were different. The control conditions and effect parameters are shown in Table 1.

[0039] Table 1

[0040]

[0041] It can be confirmed from Table 1 that when no catalyst is added (exploratory example 1.1), the tar production in the pinacolone preparation process is as high as 19.75%, and the acid liquid circulation times are only 5 times. Such a large amount of tar dissolved in hydrochloric acid creates obstacles to the recycling of hydrochloric acid and the generation of a large amount of waste acid water, which will bring extremely high environmental protection treatment costs and industrial operation costs.

[0042] When a single metal chloride is added as a reaction catalyst (exploratory examples 1.2-1.8), the number of acid water cycles in the catalytic pinacolone preparation process increases, and the purity and yield of the pinacolone product are significantly improved. Among them, the effects of using aluminum chloride, zinc chloride or nickel chloride as catalysts in exploratory examples 1.4-1.6 are not ideal; especially when aluminum chloride is used as a catalyst, although the catalyst activity is high, the large amount of tar generated creates an obstacle to the recycling and utilization of hydrochloric acid, and the yield is relatively low, so it is not possible to achieve truly clean and green production of pinacolone. Comprehensively considering the amount of tar generated, the purity of pinacolone, the yield and the number of acid water cycles, it can be verified that when the catalyst is a single metal chloride, the catalytic effect of ferric chloride, copper chloride, lanthanum chloride and neodymium chloride is better. The research and development team speculates that the electronic configuration of iron ions, copper ions and lanthanide metal ions provides empty orbits, which can be used to accommodate free electrons on the double bond of formaldehyde, thereby efficiently catalyzing the reaction of preparing pinacolone by condensation of tert-pentane chloro and formaldehyde and reducing the amount of tar generated.

[0043] In order to solve the technical problem of acid water recycling in the existing pinacolone preparation process, the research and development team of the present invention further explored the pinacolone preparation process using at least two metal chlorides as catalysts. During the exploration process, the following attempts were made:

[0044] First, the molar ratio of the compound metal chloride is 1:1 (compound of two components). As confirmed by the experimental results of Exploration Examples 1.9-1.14, the acid water recycling times of the pinacolone preparation process catalyzed by using two or more metal chlorides as catalysts increased to 48-52 times, the tar content was further reduced to, and the product purity and yield were greatly improved.

[0045] Furthermore, the research and development team of the present invention further explored a process for preparing pinacolone using a catalyst comprising ferric chloride, cupric chloride and a lanthanide Lewis acid; specifically, during the exploration process, the molar ratio of the catalyst components was tried to be 1:1:1 (three components compounded) or 1:1:1:1 (four components compounded). The experimental results of Exploration Examples 1.15-1.17 unexpectedly confirmed that the use of ferric chloride, cupric chloride and a lanthanide Lewis acid as a catalyst obtained an unexpected technical effect, which can increase the number of acid water recycling times to 60-80 times, and the purity and yield of the product remain at a high level. The research and development team of the present invention speculates that the acidity of ferric chloride and cupric chloride solutions is stronger than that of lanthanide Lewis acid solutions, and therefore ferric chloride and ferric chloride interact with hydrochloric acid in the reaction of catalyzing pinacolone, thereby increasing the number of times the acid water is utilized after the reaction; and compared with ferric chloride or cupric chloride, the lanthanide Lewis acid catalyzes pinacolone to prepare a relatively low tar content, and the dissolution of tar in hydrochloric acid is also one of the important factors that reduce the recyclability of acid water. Therefore, in Exploration Examples 1.15-1.17, by using ferric chloride, cupric chloride and lanthanide Lewis acid as catalysts, synergistic catalysis can be achieved, which not only significantly increases the number of acid water recycling times, but also maintains the amount of tar generated at a low level, and the product purity and yield are both better.

[0046] Based on the above exploratory experimental data and unexpected findings, the pinacolone preparation process of the present invention can optionally use at least one of ferric chloride, cupric chloride and lanthanum Lewis acid as a catalyst, and can further optionally use a composite of ferric chloride, cupric chloride and at least one of lanthanum chloride and neodymium chloride as a catalyst.

[0047] Example 1

[0048] Based on the experimental results of the exploratory example, this embodiment proposes a method for preparing pinacolone. Specifically, 600 kg of 30% industrial hydrochloric acid is added to the reactor, cooled to 0-10 ° C, 190 kg of isopentene precooled to -5 ° C is slowly added dropwise into the reactor under stirring, and the temperature is controlled at 0-10 ° C for 50-80 minutes; the temperature is raised to 50 ° C, and 3.5 kg of ferric chloride, 2.9 kg of copper chloride, and 15.9 kg of lanthanum chloride catalyst are added in batches (the amount of catalyst added accounts for 4% of the molar amount of isopentene) , after stirring and dissolving, slowly add 160kg of solid formaldehyde hydrochloric acid solution dropwise, heat to 70℃ and react for 3 hours; cool to room temperature, stand and separate, the upper organic phase is distilled once to obtain 249.6kg of colorless transparent liquid pinacolone, purity 99.34%, yield 92.02%; the lower hydrochloric acid layer is extracted with dichloroethane organic solvent, the acid water can be recycled 62 times after supplementing hydrogen chloride, the tar production is 3.53%, the tar production is 4.03%, the gas chromatogram of the obtained pinacolone is as follows Figure 2 .

[0049] Furthermore, the research and development team of the present invention explored the technical effects of the pinacolone preparation process such as product purity, yield, tar production, and acid water cycle times when other parameters and control conditions were the same and only the catalyst type and component ratio were different. The control conditions and effect parameters are shown in Table 2.

[0050] Table 2

[0051]

[0052] It can be confirmed from Table 2 that the molar ratio of ferric chloride, cupric chloride and lanthanide Lewis acid in the technical solution of the present invention can be selected as (1-3):(1-2):(1-3), and can further be selected as 2:1:1, or 1:1:3.

[0053] Example 2

[0054] A method for preparing pinacolone comprises the following steps: adding 600kg of 30% industrial hydrochloric acid into a reaction kettle, cooling the temperature to 0-10°C, slowly dripping 190kg of isopentene precooled to -5°C into the reaction kettle under stirring, controlling the temperature to 0-10°C and reacting for 50-80 minutes; heating the temperature to 50°C, adding ferric chloride, copper chloride and lanthanum chloride catalysts in batches (molar ratio 2:1:1), wherein the catalyst feed accounts for 9% of the total molar amount of isopentene, slowly dripping 160kg of hydrochloric acid solution of solid formaldehyde after stirring and dissolving, heating the temperature to 70°C and reacting for 4 hours; cooling the reaction kettle to room temperature, standing the reaction kettle for stratification, and subjecting the upper organic phase to one rectification to obtain 247.8kg of colorless transparent liquid pinacolone with a purity of 99.53% and a yield of 91.5%; extracting the lower hydrochloric acid layer with dichloroethane organic solvent, and recycling the acid water for 60 times after supplementing with hydrogen chloride, and producing 3.67% of tar.

[0055] Furthermore, the research and development team of the present invention explored the technical effects of the pinacolone preparation process such as product purity, yield, tar production, and acid water cycle times when other parameters and control conditions were the same and only the molar ratio of catalyst to isopentene was different. The control conditions and effect parameters are shown in Table 3.

[0056] Table 3

[0057]

[0058] It can be verified from Table 3 that in the pinacolone preparation process of the present invention, the added amount of the catalyst can be selected to be 1%-13% of the molar amount of isopentene, further 4%-13%, further 4%-9%, and further 4%. Under this working condition, both the number of acid water cycles and the amount of tar produced are better than other control conditions.

[0059] Example 3

[0060] A method for preparing pinacolone is provided. Specifically, 600 kg of industrial hydrochloric acid of different concentrations is added into a reaction kettle, the temperature is lowered to 0-10°C, 190 kg of isopentene precooled to -5°C is slowly dripped into the reaction kettle under stirring, and the temperature is controlled at 0-10°C for reaction for 50-80 minutes; the temperature is raised to 50°C, 8.8 kg of ferric chloride, 3.6 kg of copper chloride catalyst and 6.6 kg of lanthanum chloride are added in batches, 160 kg of hydrochloric acid solution of solid formaldehyde is slowly dripped after stirring and dissolving, the temperature is raised to 70°C for reaction for 4 hours; the temperature is cooled to room temperature, the mixture is allowed to stand and separate, and the purity and yield of the pinacolone colorless transparent liquid obtained by distilling the upper organic phase once are shown in Table 4 below; the lower hydrochloric acid layer is extracted with dichloroethane organic solvent, and the acid water can be recycled after supplementing with hydrogen chloride, and the amount of tar produced is shown in Table 4.

[0061] Furthermore, the research and development team of the present invention explored the technical effects of the pinacolone preparation process such as product purity, yield, tar production, and acid water recycling times when other parameters and control conditions were the same and only the concentration of hydrochloric acid used was different. The control conditions and effect parameters are shown in Table 4.

[0062] Table 4

[0063]

[0064]

[0065] It can be confirmed from Table 4 that the concentration of hydrochloric acid used in the process for preparing pinacolone of the present invention can be selected from 20wt% to 35wt%, further selected from 25wt% to 30wt%, and further selected from 30wt%.

[0066] Example 4

[0067] A method for preparing pinacolone is disclosed. Specifically, 600 kg of industrial hydrochloric acid of different concentrations is added into a reaction kettle, the temperature is lowered to 0-10°C, 190 kg of isopentene precooled to -5°C is slowly dripped into the reaction kettle under stirring, and the temperature is controlled at 0-10°C for reaction for 50-80 minutes; the temperature is raised to 50°C, 8.8 kg of ferric chloride, 3.6 kg of copper chloride catalyst and 6.6 kg of lanthanum chloride are added in batches, solid formaldehyde hydrochloric acid solution of different proportions is slowly dripped after stirring and dissolving, the temperature is raised to 70°C for reaction for 4 hours; the reaction is cooled to room temperature, allowed to stand for stratification, and the upper organic phase is subjected to a rectification to obtain a colorless transparent pinacolone liquid, the purity and yield of which are shown in Table 5; the lower hydrochloric acid layer is extracted with dichloroethane organic solvent, and the acid water can be recycled after supplementing with hydrogen chloride, and the amount of tar produced is shown in Table 5.

[0068] Furthermore, the research and development team of the present invention explored the technical effects of the pinacolone preparation process such as product purity, yield, tar production, and acid water recycling times when other parameters and control conditions were the same and only the solid formaldehyde content in the hydrochloric acid solution of the solid formaldehyde used was different. The control conditions and effect parameters are shown in Table 5.

[0069] Table 5

[0070]

[0071] As verified in Table 5, in the process for preparing pinacolone of the present invention, when the formaldehyde added dropwise is a solid formaldehyde hydrochloric acid solution, the mass ratio of hydrochloric acid to formaldehyde in the solid formaldehyde hydrochloric acid solution can be selected as (2-5):1, further selected as (3.75-5):1, and further selected as 3.75:1.

[0072] Example 5

[0073] A process for preparing pinacolone. The catalyst preparation process used in this embodiment comprises: ① dissolving 8.79kg of ferric chloride, 3.65kg of cupric chloride and 6.65kg of lanthanum chloride in deionized water, adding a mixed catalyst of lanthanum chloride and cerium chloride in an amount of 5-10% of the mass of water; ② adding inert alumina ceramic balls in an amount of 20-60% of the mass of water, heating to 95-105°C and stirring, so that the catalyst is immersed in and loaded on a carrier; ③ taking out the catalyst carrier, weighing the catalyst carrier to find that the mass of the carrier after adsorbing the catalyst is about 1-5% of the mass of the carrier (the carrier increases weight), continuing to dry the heated and loaded catalyst carrier, adjusting the drying temperature to 220-280°C, and the drying time to 5-8h, to obtain the catalyst.

[0074] like Figure 1 As shown, the process of this embodiment specifically includes: adding 600kg of 30% industrial hydrochloric acid into the reactor, cooling to 0-10°C, slowly dropping 190kg of isopentene precooled to -5°C into the reactor under stirring, controlling the temperature at 0-10°C, and reacting for 50-80 minutes; heating to 50°C, adding catalysts in batches, stirring and dissolving, slowly dropping 160kg of hydrochloric acid solution of solid formaldehyde, heating to 70°C and reacting for 4 hours; cooling to room temperature, centrifuging out the specific catalyst; standing and stratifying, the stratification time is very short, and the upper organic phase is subjected to one distillation to obtain 253.6kg of colorless transparent liquid pinacolone, with a purity of 99.95% and a yield of 93.6%; the lower hydrochloric acid layer is extracted with dichloroethane organic solvent, and the acid water can be recycled 75 times after supplementing with hydrogen chloride, and the amount of tar produced is 2.35%.

[0075] The catalyst separated in this embodiment does not need to be loaded again, and can continue to circulate and catalyze the preparation reaction of pinacolone. The research and development team of the present invention subsequently conducted a large number of exploratory experiments and found that by loading the metal chloride on the carrier, the working conditions of the metal catalyst enriched in the acid water caused by the existing process and the exploratory example can be effectively reduced. It is speculated that the reason may be related to the encapsulation of the metal atoms in the lattice or pores of the carrier after impregnation and drying. Therefore, when the metal atoms of the catalyst after completing a round of catalysis are not lost into the acid water, the catalyst can still be circulated after separation from the reaction system. Catalyst reaction.

[0076] In addition, this embodiment can prove that when a supported catalyst is used, the purity and yield of the product prepared by the catalytic pinacolone preparation process are good, and the static stratification effect is fast and clear during the post-treatment process, and the tar production is lower. The present invention solves the problems of metal catalyst enrichment and tar dissolution in acid water, reduces the process difficulty and shows a unique advantage of acid water recycling, that is, the utilization rate of acid water is increased to 75 times or more, and is a green, environmentally friendly and economically efficient pinacolone preparation process.

[0077] In addition, during the experiment, the research and development team of the present invention found that after the reaction was completed and the catalyst was centrifuged, inert alumina ceramic balls and molecular sieves were easier to separate. Therefore, the carrier used in the present invention can be selected as at least one of inert alumina ceramic balls, silica, activated carbon, and molecular sieves, and can further be selected as at least one of inert alumina ceramic balls and molecular sieves.

[0078] Example 6

[0079] A process for preparing pinacolone is disclosed. In this embodiment, 600 kg of industrial hydrochloric acid with a concentration of 30% is added into a reaction kettle, the temperature is lowered to 0-10°C, 190 kg of isopentene precooled to -5°C is slowly dripped into the reaction kettle under stirring, the temperature is controlled at 0-10°C and the reaction is carried out for 50-80 minutes, the temperature is raised to 50°C, 3.5 kg of ferric chloride, 2.9 kg of cupric chloride and 15.9 kg of lanthanum chloride are added in batches as a catalyst loaded with a molecular sieve, 160 kg of hydrochloric acid solution of solid formaldehyde is slowly dripped after stirring and dissolving, the temperature is raised to 70°C and the reaction is carried out for 3 hours; the reaction is carried out after cooling to room temperature and centrifuging out a specific catalyst; the reaction is allowed to stand for stratification, the stratification time is very short and no emulsification occurs; the upper organic phase is subjected to a rectification to obtain 254.5 kg of colorless transparent liquid pinacolone with a purity of 99.5% and a yield of 93.9%; the lower hydrochloric acid layer is extracted with an organic solvent of ethylene dichloride, the acid water can be recycled for 72 times after supplementing with hydrogen chloride, and the amount of tar produced is 2.15%.

[0080] Example 7

[0081] A process for preparing pinacolone is disclosed. In this embodiment, 600 kg of industrial hydrochloric acid with a concentration of 30% is added into a reaction kettle, the temperature is lowered to 0-10°C, 190 kg of isopentene precooled to -5°C is slowly dripped into the reaction kettle under stirring, the temperature is controlled at 0-10°C and the reaction is carried out for 50-80 minutes, the temperature is raised to 50°C, 8.75 kg of ferric chloride, 4.6 kg of cupric chloride and 6.6 kg of lanthanum chloride are added in batches as a catalyst loaded with a molecular sieve, 160 kg of hydrochloric acid solution of solid formaldehyde is slowly dripped after stirring and dissolving, the temperature is raised to 70°C and the reaction is carried out for 3 hours; the reaction is carried out after cooling to room temperature and the specific catalyst is centrifuged out; the reaction is carried out after standing and stratification, the stratification time is very short and no emulsification occurs; the upper organic phase is subjected to a rectification to obtain 254.2 kg of colorless transparent liquid pinacolone with a purity of 99.6% and a yield of 93.8%; the lower hydrochloric acid layer is extracted with an organic solvent of ethylene dichloride, the acid water can be recycled for 80 times after supplementing with hydrogen chloride, and the amount of tar produced is 2.35%.

[0082] Example 8

[0083] Taking the actual production process of pinacolone with an annual output of 13,000 tons as an example, the pinacolone preparation process shown in Examples 1 to 7 can reduce the discharge of waste acid, save more than 70 million yuan in costs per year, and create considerable economic benefits.

[0084] It should be noted that the above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions; the dimensional data of this embodiment does not necessarily limit the technical solution, but only shows one of the specific working conditions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements and modifications can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A process for preparing pinacolone, characterized in that: The reaction raw materials of the process include isopentene, hydrochloric acid and formaldehyde, and the catalyst used is composed of ferric chloride, cupric chloride and lanthanide Lewis acid; the catalyst is obtained by impregnating a mixed solution containing ferric chloride, cupric chloride and lanthanide Lewis acid with a carrier and drying it.

2. The process for preparing phenone according to claim 1, characterized in that: The lanthanide Lewis acid includes one or both of lanthanum chloride and neodymium chloride.

3. The process for preparing pinacolone according to claim 1, wherein: The molar ratio of the ferric chloride, cupric chloride and lanthanide Lewis acid is (1-3):(1-2):(1-3).

4. The process for preparing pinacolone according to claim 3, wherein: The molar ratio of the ferric chloride, the cupric chloride and the lanthanide Lewis acid is 2:1:1 or 1:1:

3.

5. The process for preparing pinacolone according to claim 1, wherein: The sum of the molar amounts of ferric chloride, cupric chloride and lanthanum Lewis acid in the catalyst accounts for 1% to 13% of the molar amount of isopentene.

6. The process for preparing pinacolone according to claim 5, characterized in that: The total molar amount of ferric chloride, cupric chloride and lanthanum Lewis acid in the catalyst accounts for 4%-13% of the molar amount of isopentene.

7. The process for preparing pinacolone according to claim 6, characterized in that: The total molar amount of ferric chloride, cupric chloride and lanthanum Lewis acid in the catalyst accounts for 4%-9% of the molar amount of isopentene.

8. The process for preparing pinacolone according to claim 7, characterized in that: The total molar amount of ferric chloride, cupric chloride and lanthanum Lewis acid in the catalyst accounts for 4% of the molar amount of isopentene.

9. The process for preparing pinacolone according to claim 1, characterized in that: The hydrochloric acid is industrial hydrochloric acid, and its concentration is 20wt%-35wt%.

10. The process for preparing pinacolone according to claim 9, characterized in that: The hydrochloric acid is industrial hydrochloric acid, and its concentration is 25wt%-30wt%.

11. The process for preparing pinacolone according to claim 10, characterized in that: The hydrochloric acid is industrial hydrochloric acid, and its concentration is 30wt%.

12. The process for preparing pinacolone according to claim 1, characterized in that: The carrier includes at least one of inert alumina ceramic balls, silicon dioxide, activated carbon and molecular sieves.

13. The process for preparing pinacolone according to claim 12, characterized in that: The carrier includes at least one of inert alumina ceramic balls and molecular sieves.

14. The process for preparing pinacolone according to any one of claims 1 to 13, characterized in that: The process comprises the following steps: a first step: reacting isopentene with hydrochloric acid; and a second step: adding a catalyst and formaldehyde to the material obtained in the first step for reaction, wherein the two-step reaction is a continuous reaction.

15. The process for preparing pinacolone according to claim 14, characterized in that: Formaldehyde is added dropwise; The formaldehyde is a formaldehyde aqueous solution or a solid formaldehyde hydrochloric acid solution.

16. The process for preparing pinacolone according to claim 15, characterized in that: The mass ratio of hydrochloric acid to formaldehyde in the solid formaldehyde hydrochloric acid solution is (2-5):

1.

17. The process for preparing pinacolone according to claim 16, characterized in that: The mass ratio of hydrochloric acid to formaldehyde in the solid formaldehyde hydrochloric acid solution is (3.75-5):

1.

18. The process for preparing pinacolone according to claim 17, characterized in that: The mass ratio of hydrochloric acid to formaldehyde in the solid formaldehyde hydrochloric acid solution is 3.75:

1.

19. The process for preparing pinacolone according to claim 14, characterized in that: The reaction temperature in the first step is 0-10°C, and the reaction time is 50-80 minutes; the reaction temperature in the second step is 60-90°C, and the reaction time is 1-6 hours.

20. The process for preparing pinacolone according to claim 19, characterized in that: The reaction temperature in the first step is 0-5°C.

21. The process for preparing pinacolone according to claim 14, characterized in that: The material after the second step reaction is cooled to room temperature and allowed to stand for stratification, and the pinacolone product is obtained in the upper layer, and the hydrochloric acid in the lower layer can be recycled.

22. The process for preparing pinacolone according to claim 21, characterized in that: The lower layer of hydrochloric acid is circulated and applied 60-80 times.

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