Preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol

Abstract

The invention relates to a preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and belongs to the technical field of organic synthesis. The preparation method of the 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol comprises the following steps: A, carrying out catalytic oxidation on an alcohol solution of 3-hydroxy-2, 2, 4-trimethylvaleraldehyde by using a supported platinum group catalyst to prepare a 2, 2, 4-trimethyl-3-oxovaleraldehyde solution; b, carrying out intramolecular aldol condensation cyclization reaction on the 2, 2, 4-trimethyl-3-oxovaleraldehyde solution obtained in the step A under an alkaline condition to prepare 3-hydroxy-2, 2, 4, 4-tetramethyl cyclobutanone; c.3-hydroxy-2, 2, 4, 4-tetramethyl cyclobutanone is subjected to hydrogenation reduction by using a platinum-loaded or ruthenium-loaded or nickel-loaded metal catalyst, such that CBDO is obtained; the catalytic oxidation temperature in the step A is 10-100 DEG C; the pressure is 0.1 to 30 bar. The CBDO is prepared by adopting four steps of a brand new process route.

Description

Technical Field

[0001] The invention relates to a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and belongs to the technical field of organic synthesis. Background Art

[0002] 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (hereinafter referred to as CBDO) is an important aliphatic diol polyester monomer. Due to the special rigid group four-membered ring in the structure, it can be used to produce high-performance copolyester PCTG with high glass transition temperature, high transparency and high barrier properties. For example, the American Eastman new generation polyester Tritan, which is widely used in the market, is copolymerized by CBDO, PTA and 1,4-CHDM. Its Tg temperature is above 110°C. Tritan polyester does not contain bisphenol A. Compared with polycarbonate PC, it has significant advantages in the field of food contact. As a monomer for producing high-temperature polyurethane hard segment, CBDO can significantly enhance the glass transition temperature of polyester, improve weather resistance and transparency, and is an ideal raw material to replace polycarbonate.

[0003] According to literature reports, CBDO can be used to produce BPA-free epoxy resins, which can replace traditional epoxy resins in the coating of food packaging. The United States has already started using it, but it is not available in China yet. As people pay more and more attention to food safety and health, the domestic market size is expected to grow gradually. CBDO can also produce polyester diols for high-temperature and sun-resistant powder coatings. Overall, the CBDO market size cannot meet domestic demand.

[0004] However, due to the long synthesis route of CBDO, high technical barriers and high manufacturing costs,

[0005] The currently reported process routes for the industrial preparation of CBDO all involve first preparing dimethyl ketone (DMK) and then dimerizing it to 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCK). There are two routes for preparing TMCK.

[0006] One is to use isobutyric anhydride as raw material and crack it at high temperature (above 500°C) to remove water molecules to generate DMK dimerized into TMCK. This is represented by the technology of US Patents US5169996 / US5258556. This method has long been industrialized in Eastman, USA.

[0007]

[0008] In China, Zhejiang University and Wanhua Chemical are the representatives, and there are a large number of patent reports on this route.

[0009] However, due to the difficulty of technical barriers, there has been no industrial demonstration device. The advantage of this technical route is that the gas phase method is easy to achieve continuous production and scale, but the disadvantages are high temperature energy consumption, high technical barriers, and dangerous high temperature cracking production process.

[0010] The second method is to use isobutyryl chloride at medium and low temperature (30-140°C) with triethylamine as a dechlorinating agent for dehydrochlorination to generate dimethyl ketone DMK, which is dimerized into tetramethylcyclobutanedione TMCK. This technology is represented by German BASF patent US6559343. At present, many domestic companies have published patents on this method, such as CN112457170, which is nothing more than further improvement on the basis of US6559343.

[0011]

[0012] The advantages of this route are low energy consumption and a relatively safe production process. The disadvantages are that the liquid-solid phase reaction is not easy to be continuous and cannot be scaled up, and a large amount of triethylamine hydrochloric acid needs to be recycled, resulting in high production costs. The quality of the finished product is also affected by the chlorine content, especially the performance and application of high-end electronic polymer materials downstream.

[0013] Patent CN 118290230 proposes a synthetic route:

[0014]

[0015] The patent uses 2,2,4-trimethyl-1,3-pentanediol, an intermediate byproduct of texanol, as a starting material to synthesize CBDO in three steps. However, the patent has the following shortcomings:

[0016] Its patent starts with trimethylpentanediol, a byproduct of the synthesis of tridecanol from isobutyraldehyde. Although the raw material seems to be extensive, its source is actually limited, and the complex composition of the byproduct affects the subsequent preparation and is not conducive to the purification of the finished product. When preparing 2,2,4-trimethyl-3-oxopentanal, its patent uses a chemical oxidant, sodium hypochlorite, for selective oxidation, which has the disadvantages of large wastewater volume and low time-space yield. When synthesizing 3-hydroxy-2,2,4,4-tetramethylcyclobutanone, its patent uses talc containing the precious metal ruthenium for catalytic condensation, and the preparation process is complicated. The catalyst contains precious metals, resulting in high costs. When preparing CBDO by hydrogenation as described in its patent, its catalyst uses precious metal iridium, resulting in high costs. Summary of the invention

[0017] The purpose of the present invention is to provide a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0018] To achieve the purpose of the present invention, the preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanediol comprises:

[0019] A. catalytically oxidizing an alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal with a supported platinum catalyst to prepare a 2,2,4-trimethyl-3-oxopentanal solution;

[0020] B. subjecting the 2,2,4-trimethyl-3-oxopentanal solution of step A to an intramolecular aldol condensation cyclization reaction under alkaline conditions to prepare 3-hydroxy-2,2,4,4-tetramethylcyclobutanone;

[0021] C. 3-Hydroxy-2,2,4,4-tetramethylcyclobutanone is hydrogenated and reduced with a platinum, ruthenium or nickel metal catalyst to obtain CBDO;

[0022] The temperature of the catalytic oxidation in step A is 10-100° C.; the pressure is 0.1-30 bar; the oxidant is at least one of air, pure oxygen, and hydrogen peroxide; the supported platinum group catalyst is platinum-supported activated carbon or palladium-supported activated carbon, platinum-supported alumina or palladium-supported alumina, and a platinum group supported catalyst modified with a mixture of the second metal copper, zinc, and lead.

[0023] In a specific embodiment, the supported platinum group catalyst is at least one of Pt / Al2O3, Pt / C, and Pt-Cu / Al2O3.

[0024] In a specific embodiment, the supported platinum group catalyst is prepared by an equal volume impregnation method, a supersaturated impregnation method or a co-precipitation method; the loading amount of the platinum group in the supported platinum group catalyst is 0.1 to 10 wt%, and the preferred loading amount is 0.1 to 5 wt%; the supported platinum group catalyst is preferably prepared by an impregnation method, the impregnation temperature is 10 to 100° C., the impregnation time is 1 to 24 h, the reduction temperature is 20 to 300° C., and the reduction time is 1 to 10 h; the calcination temperature of the co-precipitation method is 400 to 500° C., the time is 2 to 6 h, and the reduction temperature is 200 to 300° C., and the time is 2 to 4 h.

[0025] In a specific embodiment, the preferred temperature for catalytic oxidation in step A is 20-80° C.; the preferred pressure is 0.1-10 bar; and the concentration of the hydrogen peroxide is preferably in the range of 1-5%.

[0026] In a specific embodiment, the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal comprises: subjecting isobutyraldehyde and an alcohol solvent to an aldol condensation reaction under the catalysis of an alkaline catalyst to obtain 2,2,4-trimethyl-3-hydroxy-pentanal.

[0027] In a specific embodiment, the solvent of the alcohol solution in step A, the solvent in step B, the solvent in step C, and the alcohol solvent in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal are all: at least one of methanol, ethanol, propanol, and butanol, preferably methanol and ethanol; the amount of the solvent is 2 to 5 times the mass of isobutyraldehyde, 3-hydroxy-2,2,4-trimethylpentanal or 3-hydroxy-2,2,4,4-tetramethylcyclobutanone.

[0028] In a specific embodiment, the alkaline catalyst in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the catalyst of the reaction in step B are heterogeneous alkaline catalysts or homogeneous alkaline catalysts; preferably strong base-supported catalysts, alkaline earth metal oxide-supported catalysts, alkali metal hydroxide aqueous solutions, alkali metal carbonate aqueous solutions, and organic strong bases; more preferably at least one of KF / AL2O3, MgO / AL2O3, CaO / AL2O3, KOH aqueous solution, NaOH aqueous solution, K2CO3 aqueous solution, Na2CO3 aqueous solution, KHCO3 aqueous solution, NaHCO3 aqueous solution, triethylamine, and trimethylamine;

[0029] Preferably, the MgO / Al2O3, KF / AL2O3, and CaO / AL2O3 are prepared by coprecipitation, and the calcination temperature of the coprecipitation is 400-500°C and the time is 2-6h;

[0030] More preferably, the magnesium oxide loading in the heterogeneous alkaline catalyst is 1 to 60 wt%, and the calcium oxide loading is 1 to 60 wt%; the concentration of the alkali metal hydroxide and the organic tertiary amine in the homogeneous catalyst is 0.1 to 20 wt%, and the pH value is preferably 8 to 12, preferably 8 to 10.

[0031] In a specific embodiment, the preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the reaction temperature in step B are both 10-100°C, preferably 20-80°C.

[0032] In a specific embodiment, the reaction temperature in step C is 60-200°C, preferably 90-180°C, and the reaction pressure is 10-100 bar, preferably 30-60 bar; the catalyst in step C is a nickel-supported metal catalyst, preferably at least one of Ni-V / TiO2 and Ni-Sn / TiO2; the catalyst in step C is preferably prepared by impregnation method, and the reduction temperature prepared by impregnation method is 200-400°C and the time is 2-4h.

[0033] In a specific embodiment, steps A to C or the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal are all carried out in a fixed bed continuous reactor, and the liquid space velocity range of the reaction is: 0.1 to 10 h -1 , preferably 0.5 to 5 hours -1 .

[0034] Beneficial effects:

[0035] 1. The present invention adopts a new process route different from any existing literature, using isobutylaldehyde, a bulk and cheap raw material, as the starting material to prepare CBDO through four steps of condensation, selective oxidation, intramolecular condensation, and hydrogenation reduction.

[0036] 2. The present invention has fewer reaction steps and the investment in industrialization will be reduced: the Eastman process technology, which has been industrialized on a large scale, also uses isobutyraldehyde as the starting material and obtains CBDO through five steps including dehydration, cracking, dimerization and cyclization, and hydrogenation. The present invention only requires four steps to obtain CBDO. Moreover, the production steps of the present invention do not have a high cracking step at a temperature above 400°C, so the energy consumption is lower. In addition, the reaction adopts a continuous process and equipment, and it can be predicted that the product quality and product competitiveness will be improved after industrialization. DETAILED DESCRIPTION

[0037] To achieve the purpose of the present invention, the preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanediol comprises:

[0038] A. catalytically oxidizing an alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal with a supported platinum catalyst to prepare a 2,2,4-trimethyl-3-oxopentanal solution;

[0039] B. subjecting the 2,2,4-trimethyl-3-oxopentanal solution of step A to an intramolecular aldol condensation cyclization reaction under alkaline conditions to prepare 3-hydroxy-2,2,4,4-tetramethylcyclobutanone;

[0040] C. 3-Hydroxy-2,2,4,4-tetramethylcyclobutanone is hydrogenated and reduced with a platinum, ruthenium or nickel metal catalyst to obtain CBDO;

[0041] The temperature of the catalytic oxidation in step A is 10-100° C.; the pressure is 0.1-30 bar; the oxidant is at least one of air, pure oxygen, and hydrogen peroxide; the supported platinum group catalyst is platinum-supported activated carbon or palladium-supported activated carbon, platinum-supported alumina or palladium-supported alumina, and a platinum group supported catalyst modified with a mixture of the second metal copper, zinc, and lead.

[0042] The reactor can be in the form of a batch reactor or a continuous reactor.

[0043] The reaction pressure of step B is normal pressure or a normal pressure system reaction under the protection of an inert gas.

[0044] The reaction of step A of the present invention is a selective oxidation reaction, and the hydroxyl group OH at position 3 needs to be oxidized to the ketone carbonyl, while the terminal aldehyde carbonyl should not be oxidized, which is the technical difficulty of this step and one of the key technologies of the present invention. The use of chemical oxidants such as potassium permanganate, hydrogen peroxide, sodium dichromate, etc., which are strong oxidants, will also oxidize the terminal aldehyde carbonyl, which is an undesirable result and needs to be avoided. Therefore, there is a mild chemical oxidant sodium hypochlorite, which can be found in a large number of literature reports, such as J.AM.Chem.Soc.2006,128,8412-8413, but the sodium hypochlorite oxidation method has its obvious disadvantages. The concentration of industrial sodium hypochlorite is about 10%wt, which results in a large amount of wastewater, increased environmental protection implementation investment and low production efficiency due to low liquid air velocity. These are the defects of the sodium hypochlorite oxidation method itself, making it impossible to use it in the field of large-scale material production in step A of the present invention for preparing CBDO. The catalytic oxidation method used in the present invention is very suitable. The present invention selectively oxidizes hydroxyl groups to ketone carbonyl groups without oxidizing the terminal aldehyde carbonyl groups or minimizing their oxidation. The solid and liquid can be easily separated in industrial operations, there is no wastewater treatment, and the equipment is simple and the investment is small.

[0045] In a specific embodiment, the supported platinum group catalyst is at least one of Pt / Al2O3, Pt / C, and Pt-Cu / Al2O3.

[0046] In a specific embodiment, the supported platinum group catalyst is prepared by an equal volume impregnation method, a supersaturated impregnation method or a co-precipitation method; the loading amount of the platinum group in the supported platinum group catalyst is 0.1 to 10 wt%, and the preferred loading amount is 0.1 to 5 wt%; the supported platinum group catalyst is preferably prepared by an impregnation method, the impregnation temperature is 10 to 100° C., the impregnation time is 1 to 24 h, the reduction temperature is 20 to 300° C., and the reduction time is 1 to 10 h; the calcination temperature of the co-precipitation method is 400 to 500° C., the time is 2 to 6 h, and the reduction temperature is 200 to 300° C., and the time is 2 to 4 h.

[0047] In a specific embodiment, the preferred temperature for catalytic oxidation in step A is 20-80° C.; the preferred pressure is 0.1-10 bar; and the concentration of the hydrogen peroxide is preferably in the range of 1-5%.

[0048] In a specific embodiment, the preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal comprises: subjecting isobutyraldehyde and an alcohol solvent to an aldol condensation reaction under the catalysis of an alkaline catalyst to obtain 2,2,4-trimethyl-3-hydroxy-pentanal. The reaction pressure of the preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal is atmospheric pressure or atmospheric pressure system reaction under the protection of an inert gas, and the reactor form can be a batch reactor or a continuous reactor.

[0049] The new process route of the present invention is as follows:

[0050]

[0051] In a specific embodiment, the solvent of the alcohol solution in step A, the solvent in step B, the solvent in step C, and the alcohol solvent in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal are all: at least one of methanol, ethanol, propanol, and butanol, preferably methanol and ethanol; the amount of the solvent is 2 to 5 times the mass of isobutyraldehyde, 3-hydroxy-2,2,4-trimethylpentanal or 3-hydroxy-2,2,4,4-tetramethylcyclobutanone.

[0052] In a specific embodiment, the alkaline catalyst in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the catalyst of the reaction in step B are heterogeneous alkaline catalysts or homogeneous alkaline catalysts; preferably strong base-supported catalysts, alkaline earth metal oxide-supported catalysts, alkali metal hydroxide aqueous solutions, alkali metal carbonate aqueous solutions, and organic strong bases; more preferably at least one of KF / AL2O3, MgO / AL2O3, CaO / AL2O3, KOH aqueous solution, NaOH aqueous solution, K2CO3 aqueous solution, Na2CO3 aqueous solution, KHCO3 aqueous solution, NaHCO3 aqueous solution, triethylamine, and trimethylamine;

[0053] Preferably, the MgO / Al2O3, KF / AL2O3, and CaO / AL2O3 are prepared by coprecipitation, and the calcination temperature of the coprecipitation is 400-500°C and the time is 2-6h;

[0054] More preferably, the magnesium oxide loading in the heterogeneous alkaline catalyst is 1 to 60 wt%, and the calcium oxide loading is 1 to 60 wt%; the concentration of the alkali metal hydroxide and the organic tertiary amine in the homogeneous catalyst is 0.1 to 20 wt%, and the pH value is preferably 8 to 12, preferably 8 to 10.

[0055] Heterogeneous alkaline catalysts are used because they have advantages known to all technicians in the chemical industry, such as easy separation of solid and liquid in industrial operations, no wastewater treatment, simple equipment and low investment.

[0056] In a specific embodiment, the preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the reaction temperature in step B are both 10-100°C, preferably 20-80°C.

[0057] In a specific embodiment, the reaction temperature in step C is 60-200°C, preferably 90-180°C, and the reaction pressure is 10-100 bar, preferably 30-60 bar; the catalyst in step C is a nickel-supported metal catalyst, preferably at least one of Ni-V / TiO2 and Ni-Sn / TiO2; the catalyst in step C is preferably prepared by impregnation method, and the reduction temperature prepared by impregnation method is 200-400°C and the time is 2-4h.

[0058] In a specific embodiment, steps A to C or the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal are all carried out in a fixed bed continuous reactor, and the liquid space velocity range of the reaction is: 0.1 to 10 h -1 , preferably 0.5 to 5 hours -1 .

[0059] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0060] Example 1

[0061] Synthesis of 3-hydroxy-2,2,4-trimethylpentanal:

[0062] 2 mol of isobutyraldehyde and 300 ml of methanol were uniformly mixed and continuously fed into a fixed bed reactor filled with a heterogeneous solid catalyst after being preheated to 60°C through a plunger metering pump. The fixed bed reactor had heating and cooling measures to maintain the required temperature for the reaction. Sampling and analysis were performed, and the relevant data were as follows in Table 1:

[0063] Table 1 Partial reaction conditions and effects of Example 1

[0064] Basic catalyst Reactor temperature Liquid air speed Conversion rate Selectivity <![CDATA[FK / AL2O3]]> 70～80℃ <![CDATA[1.0h -1 ]]> 85％ 95％ <![CDATA[MgO / AL2O3]]> 70～80℃ <![CDATA[1.0h -1 ]]> 92％ 96％ <![CDATA[CaO / AL2O3]]> 70～80℃ <![CDATA[1.0h -1 ]]> 93％ 97％

[0065] The preparation method of the alkaline catalyst adopts the coprecipitation method to prepare the heterogeneous alkaline catalyst. Generally speaking, the calcination temperature is 400-500°C and the time is 2-6 hours. The specific preparation method can be widely found in the literature and materials, which will not be described here. The alkaline catalyst MgO / AL2O3 magnesium oxide loading is 55%, and the CaO / AL2O3 calcium oxide loading is specifically 50%.

[0066] Example 2

[0067] Synthesis of 3-hydroxy-2,2,4-trimethylpentanal:

[0068] 2mol of isobutyraldehyde, 300ML of methanol, and a homogeneous alkaline catalyst are mixed and continuously fed into a SUS316L pipe reactor preheated to 70°C through a plunger metering pump. The reactor is heated to the required temperature in an oil bath. A back pressure valve is used at the end of the reactor to continuously discharge the reaction liquid. After adjusting the pH to neutral, it is convenient to sample and analyze the results. The relevant data are shown in Table 2:

[0069] Table 2 Partial reaction conditions and effects of Example 2

[0070] Basic catalyst Reactor temperature pH Conversion rate Selectivity 3% NaOH 70～80℃ 8～10 94％ 87％ 3% KOH 70～80℃ 8～10 95％ 96％ Triethylamine 70～80℃ 8～10 89％ 98％

[0071] Example 3

[0072] Synthesis of 2,2,4-trimethyl-3-oxopentanal:

[0073] The 3-hydroxy-2,2,4-trimethylpentanal solution obtained in Example 1 was continuously fed into a fixed bed reactor filled with a platinum group catalyst after being preheated to 60° C. by a plunger metering pump. Air was introduced to maintain the required pressure. The fixed bed reactor had heating and cooling measures to maintain the required temperature for the reaction. Sampling and analysis were performed. The relevant data are shown in Table 3 below:

[0074] Table 3 Partial reaction conditions and effects of Example 3

[0075] catalyst Reactor temperature Reactor pressure Liquid air speed Conversion rate Selectivity <![CDATA[Pt / AL2O3]]> 65～75℃ 10bar <![CDATA[1.0h -1 ]]> 91％ 80％ Pt / C 65～75℃ 10bar <![CDATA[1.0h -1 ]]> 86％ 78％ <![CDATA[Pt-Cu / AL2O3]]> 65～75℃ 10bar <![CDATA[1.0h -1 ]]> 91％ 93％

[0076] The oxidation catalyst is prepared by co-precipitation method, and the Pt metal content is controlled at 1-3%wt. Generally speaking, the calcination temperature is 400-500°C, the time is 2-6h, and the reduction temperature is 200-300°C, the time is 2-4h. The specific preparation method can be widely found in literature and materials, so it will not be described here.

[0077] Example 4

[0078] Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone:

[0079] The 2,2,4-trimethyl-3-oxopentanal solution obtained in Example 3 was continuously fed into a fixed bed reactor filled with a heterogeneous solid catalyst after being preheated to 70° C. by a plunger metering pump. The fixed bed reactor had heating and cooling measures to maintain the required temperature for the reaction. Sampling and analysis were performed, and the relevant data were as follows in Table 4:

[0080] Table 4 Partial reaction conditions and effects of Example 4

[0081] Basic catalyst Reactor temperature Liquid air speed Conversion rate Selectivity <![CDATA[FK / AL2O3]]> 75～80℃ <![CDATA[1.0h -1 ]]> 89％ 90％ <![CDATA[MgO / AL2O3]]> 75～80℃ <![CDATA[1.0h -1 ]]> 90％ 93％ <![CDATA[CaO / AL2O3]]> 75～80℃ <![CDATA[1.0h -1 ]]> 92％ 95％

[0082] The alkaline catalyst preparation method adopts the co-precipitation method to prepare the heterogeneous alkaline catalyst. Generally speaking, the calcination temperature is 400-500°C and the time is 2-6h. The specific preparation method can be widely found in the literature and materials, so it will not be described here.

[0083] Example 5

[0084] Synthesis of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO)

[0085] The 3-hydroxy-2,2,4,4-tetramethylcyclobutanone solution obtained in Example 4 was continuously fed into a fixed bed reactor filled with a nickel / ruthenium catalyst after being preheated to 130° C. by a plunger metering pump. The hydrogen maintained the required pressure. The fixed bed reactor had heating and cooling measures to maintain the required temperature for the reaction. Sampling and analysis were performed. The relevant data are shown in Table 5 below:

[0086] Table 5 Partial reaction conditions and effects of Example 5

[0087] Basic catalyst Reactor temperature Reactor pressure Liquid air speed Conversion rate Selectivity <![CDATA[Ru / AL2O3]]> 130～150℃ 45~50bar <![CDATA[1.0h -1 ]]> 98％ 95％ <![CDATA[Ni-V / TiO2]]> 160～180℃ 50~60bar <![CDATA[1.0h -1 ]]> 98％ 94％ <![CDATA[Ni-Sn / TiO2]]> 160～180℃ 50~60bar <![CDATA[1.0h -1 ]]> 98％ 93％

[0088] The hydrogenation catalyst preparation method described herein is as follows: Ru / AL2O3 is prepared by an impregnation method, the ruthenium metal content is controlled at 1-3%wt, the reduction temperature is 200-400°C, and the time is 2-6h; Ni-V / TiO2 and Ni-Sn / TiO2 catalysts, based on the total mass of the catalyst, the nickel content is 10-60wt%, and the vanadium content is 1-20wt%. The catalysts are prepared by a coprecipitation method, generally the reduction temperature is 300-400°C, and the time is 2-6h. The specific preparation method can be widely found in literature and materials, and will not be elaborated here.

Claims

1. A method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, characterized in that: The method comprises: A. catalytically oxidizing an alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal with a supported platinum catalyst to prepare a 2,2,4-trimethyl-3-oxopentanal solution; B. subjecting the 2,2,4-trimethyl-3-oxopentanal solution of step A to an intramolecular aldol condensation cyclization reaction under alkaline conditions to prepare 3-hydroxy-2,2,4,4-tetramethylcyclobutanone; C. 3-Hydroxy-2,2,4,4-tetramethylcyclobutanone is hydrogenated and reduced with a platinum, ruthenium or nickel metal catalyst to obtain CBDO; The temperature of the catalytic oxidation in step A is 10-100° C.; the pressure is 0.1-30 bar; the oxidant is at least one of air, pure oxygen, and hydrogen peroxide; the supported platinum group catalyst is platinum-supported activated carbon or palladium-supported activated carbon, platinum-supported alumina or palladium-supported alumina, and a platinum group supported catalyst modified with a mixture of the second metal copper, zinc, and lead.

2. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1, characterized in that: The supported platinum group catalyst is at least one of Pt / Al2O3, Pt / C, and Pt-Cu / Al2O3.

3. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The supported platinum group catalyst is prepared by an equal volume impregnation method, a supersaturated impregnation method or a co-precipitation method; the loading amount of the platinum group in the supported platinum group catalyst is 0.1 to 10 wt%, and the preferred loading amount is 0.1 to 5 wt%; the supported platinum group catalyst is preferably prepared by an impregnation method, with an impregnation temperature of 10 to 100° C., an impregnation time of 1 to 24 h, a reduction temperature of 20 to 300° C., and a reduction time of 1 to 10 h; the calcination temperature of the co-precipitation method is 400 to 500° C., the time is 2 to 6 h, and the reduction temperature is 200 to 300° C., and the time is 2 to 4 h.

4. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The temperature of the catalytic oxidation in step A is 20-80° C.; the pressure is 0.1-10 bar; and the concentration range of the hydrogen peroxide is preferably 1-5%.

5. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal comprises: subjecting isobutyraldehyde and an alcohol solvent to an aldol condensation reaction under the catalysis of an alkaline catalyst to obtain 2,2,4-trimethyl-3-hydroxy-pentanal.

6. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 5, characterized in that: The solvent of the alcohol solution in step A, the solvent in step B, the solvent in step C, and the alcohol solvent in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal are all at least one of methanol, ethanol, propanol, and butanol, preferably methanol and ethanol; the amount of the solvent is 2 to 5 times the mass of isobutyraldehyde, 3-hydroxy-2,2,4-trimethylpentanal or 3-hydroxy-2,2,4,4-tetramethylcyclobutanone.

7. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 5, characterized in that: The alkaline catalyst in the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the catalyst in the reaction in step B are heterogeneous alkaline catalysts and homogeneous alkaline catalysts; preferably strong base supported catalysts, alkaline earth metal oxide supported catalysts, alkali metal hydroxide aqueous solutions, alkali metal carbonate aqueous solutions, organic strong bases; more preferably at least one of KF / AL2O3, MgO / AL2O3, CaO / AL2O3, KOH aqueous solution, NaOH aqueous solution, K2CO3 aqueous solution, Na2CO3 aqueous solution, KHCO3 aqueous solution, NaHCO3 aqueous solution, triethylamine, and trimethylamine; Preferably, the MgO / Al2O3, KF / AL2O3, and CaO / AL2O3 are prepared by coprecipitation, and the calcination temperature of the coprecipitation is 400-500°C and the time is 2-6h; More preferably, the magnesium oxide loading in the heterogeneous alkaline catalyst is 1 to 60 wt%, and the calcium oxide loading is 1 to 60 wt%; the concentration of the alkali metal hydroxide and the organic tertiary amine in the homogeneous catalyst is 0.1 to 20 wt%, and the pH value is preferably 8 to 12, preferably 8 to 10.

8. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 5, characterized in that: The temperature of the preparation method of the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal and the reaction in step B are both 10-100°C, preferably 20-80°C.

9. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 1 or 2, characterized in that: The reaction temperature in step C is 60-200°C, preferably 90-180°C, and the reaction pressure is 10-100 bar, preferably 30-60 bar; the catalyst in step C is a nickel-supported metal catalyst, preferably at least one of Ni-V / TiO2 and Ni-Sn / TiO2; the catalyst in step C is preferably prepared by impregnation method, and the reduction temperature of the impregnation method is 200-400°C and the time is 2-4h.

10. The method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol according to claim 5, characterized in that: Steps A to C or the method for preparing the alcohol solution of 3-hydroxy-2,2,4-trimethylpentanal all use a fixed bed continuous reactor for continuous reaction, and the liquid space velocity range of the reaction is: 0.1 to 10h -1 , preferably 0.5 to 5 hours -1 .

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