CN110143871B

CN110143871B - Preparation method of dicarboxylic acid diol ester

Info

Publication number: CN110143871B
Application number: CN201810143937.2A
Authority: CN
Inventors: 刘素洁; 温朗友; 郜亮; 纪洪波; 夏玥穜; 俞芳; 董明会; 喻惠利
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2018-02-12
Filing date: 2018-02-12
Publication date: 2022-02-08
Anticipated expiration: 2038-02-12
Also published as: CN110143871A

Abstract

The invention relates to a preparation method of dicarboxylic acid diol ester, which comprises the following steps: in the presence of a catalyst, an aliphatic dicarboxylic acid is contacted with a monohydric alcohol for reaction, and simultaneously, water generated in the reaction is removed; the catalyst is a bulk catalyst containing silicon, tin and oxygen and contains Sn-O-Si bonds. The method has the advantages of high conversion rate and selectivity, less circulating materials and stronger atom economy.

Description

Preparation method of dicarboxylic acid diol ester

Technical Field

The invention relates to a preparation method of dicarboxylic acid diol ester, in particular to a preparation method of aliphatic dicarboxylic acid diol ester which can be used as a plasticizer.

Background

The plasticizer is an assistant which is added into polymer materials such as plastics, resins, elastomers and the like to improve the processability, plasticity, flexibility and stretchability of the polymer materials. Plasticizers can be divided into primary and secondary plasticizers. The aliphatic dibasic acid ester plasticizer has unique low-temperature performance and is generally used as an auxiliary plasticizer for improving the cold resistance of materials.

CN107188803A discloses a production method of a cold-resistant plasticizer dodecanedioic acid diester, titanate is used as a catalyst, and the molar ratio of alkyd is 2.6: 1-2.9: 1. CN1618847A discloses a dibasic acid ester plasticizer and a method for producing the same, wherein alcohol used in the method contains ether bond. CN104592015A proposes that sebacic acid and 2-ethylhexanol are used as raw materials, stannous oxide is used as a catalyst to prepare dioctyl sebacate, alkali is added for neutralization and water washing after the reaction is finished, reduced pressure distillation and activated carbon adsorption filtration are carried out, and then a refined product is obtained.

Esterification is one of the most important organic reactions, and products thereof are widely used in various fields of chemical industry. The esterification reaction generally requires the use of a catalyst, and the catalysts used can be divided into acidic catalysts and non-acidic catalysts. The acidic catalyst is some inorganic acids and organic acids, and has the main disadvantages of poor reaction selectivity, corrosion, pollution, incapability of recycling the catalyst, difficulty in product aftertreatment and the like. The non-acidic catalyst is mainly compounds of metals such as aluminum, titanium, zirconium, tin, zinc, magnesium, antimony, bismuth and the like, and the compounds can be used alone or can be prepared into a composite catalyst, so that the catalyst is generally non-corrosive and has relatively high reaction selectivity. Titanates are a non-acidic homogeneous catalyst and, despite their high catalytic activity, require removal of the catalyst from the reaction product, making the work-up of the product difficult. Stannous oxide has high catalytic activity as an esterification catalyst, but stannous oxide is easy to refine and has quick inactivation when catalyzing the esterification reaction of alcohol acid, which is not favorable for long-period operation of continuous esterification process and repeated use of catalyst of intermittent esterification process.

CN1760339A, CN1740277A disclose supported catalysts of divalent tin and are used for esterification decarboxylation of high acid crude oil or distillate oil. US3520915 also discloses supported catalysts of divalent tin, which catalysts are used for the preparation of unsaturated aliphatic nitriles. Wenlei Xie et al disclose Supported Catalysts of tetravalent Tin, which Catalysts are used in the Transesterification of Soybean Oil (silicon-Supported Tin Oxides as a heterologous Acid Catalysts for Transesterification of Soybean Oil, Ind. Eng. chem. Res.2012,51, 225-phase 231). None of these catalysts solves the problems of catalyst refinement and deactivation well. Vinicius et al disclose a complex oxide of aluminum and divalent tin and use it for the esterification of soybean oil fatty acids, and the results show that "the catalytic activity of the complex oxide is reduced compared to stannous oxide" (Metal oxides as a heterologous catalysts for esterification of fatty acids from soybean oil, Fuel Processing Technology, 2011, 92, 53-57).

Disclosure of Invention

The invention provides a preparation method of dicarboxylic acid diol ester, which uses a new esterification catalyst, thereby having higher catalytic activity and selectivity, and the catalyst is easy to separate from reaction products and can be repeatedly used.

Specifically, the present invention mainly includes the following contents:

1. a method for preparing diol dicarboxylic acid ester comprises the following steps: in the presence of a catalyst, an aliphatic dicarboxylic acid is contacted with a monohydric alcohol for reaction, and simultaneously, water generated in the reaction is removed; the catalyst is a bulk phase catalyst containing silicon, tin and oxygen and contains Sn-O-Si bonds; the monohydric alcohol has a structure shown in a formula R-OH, wherein R is unsubstituted alkyl or alkyl containing ether bonds.

2. The preparation method according to 1, characterized in that the monohydric alcohol is one or more of C6-C14 alkanol.

3. The process according to any one of the preceding claims, characterized in that the monoalcohol is n-butanol, n-hexanol, n-octanol, isooctanol, n-decanol, isodecanol, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, diethylene glycol ethyl butyl ether, dipropylene glycol methyl ether or dipropylene glycol tert-butyl ether.

4. The preparation method according to any one of the preceding claims, characterized in that the aliphatic dicarboxylic acid is one or more of dicarboxylic acids having a carbon number of 6-14 (preferably 1, 6-adipic acid, 1, 8-suberic acid, 1, 9-azelaic acid or 1, 10-sebacic acid).

5. A process according to any one of the preceding claims, characterized in that an inert gas, preferably nitrogen, is introduced during the reaction.

6. The process according to any one of the preceding claims, characterized in that the reaction is carried out under reflux for 2 to 10 hours (preferably 3 to 5 hours).

7. A process according to any one of the preceding claims, characterized in that the molar ratio of alcohol to acid is 2: 1-4: 1 (preferably 2.4:1 to 3: 1).

8. The process according to any of the preceding claims, characterized in that the amount of catalyst used is 0.1% to 10% (preferably 0.5% to 2%) of the total mass of the reactants.

9. The preparation method according to any one of the preceding claims, characterized by further comprising: after the reaction is finished, a step of removing light components by reduced pressure distillation and a step of decoloring.

10. The production method according to any one of the preceding claims, characterized in that the catalyst is a bulk catalyst composed of silicon, tin and oxygen.

11. The process according to any one of the preceding claims, wherein the molar ratio of silicon to tin in the catalyst is 0.8 to 6 (preferably 1.5 to 5).

12. The production method according to any one of the above, wherein the mass fraction of tin in the catalyst is 23% to 65% (preferably 26% to 53%).

13. The process according to any of the preceding claims, characterized in that the valence of the tin in the catalyst is divalent or tetravalent.

14. A process according to any one of the preceding claims, characterized in that the catalyst has a Raman spectrum at 237cm^-1A characteristic peak is present in the vicinity.

15. A process according to any one of the preceding claims, characterized in that the catalyst has a Raman spectrum at 110cm^-1Near and 211cm^-1There is no vibration peak or a characteristic peak with relatively small intensity in the vicinity.

16. The production method according to any one of the preceding claims, characterized in that the catalyst has an XRD pattern free from peaks characteristic to tin oxide crystals.

17. A process according to any one of the preceding claims, characterized in that the catalyst is an amorphous solid.

18. A process according to any one of the preceding claims, characterized in that after the end of the reaction, the catalyst is separated off and is reused in the process.

19. A processing method of plastics is characterized in that dicarboxylic acid diol ester prepared by any one of the methods 1-18 is used as a plasticizer.

In the prior art, stannous oxide is a better non-acidic esterification catalyst, but the catalyst has the problem of quick inactivation, more seriously, the catalyst is easy to refine, so that the catalyst is difficult to separate from a reaction product, great difficulty is brought to actual production, and the problems can not be ideally solved by loading or preparing a composite metal oxide in the prior art. The inventor unexpectedly discovers in tests that the high-temperature esterification catalyst which has higher activity and better selectivity and is not thinned can be prepared by coprecipitation of silicate and tin salt; it is also unexpected that the tetravalent tin catalysts obtained by this process also have good activity, selectivity and thermal stability. The present inventors have proposed and completed the present invention on the basis of this finding.

The invention has the following advantages: the catalyst used contains new tin species and the combination of silicon, tin and oxygen is firmer, so that the reaction has higher conversion rate and selectivity; the catalyst is easy to separate from the reaction product and can be repeatedly used; when the reactant dosage is close to the stoichiometric ratio of the reaction, high conversion rate and selectivity can be still achieved, the circulating material is less, and the atom economy is stronger. Furthermore, the process of the present invention does not need to include washing steps (alkaline and aqueous washing).

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

FIG. 1 is an XPS photoelectron spectrum of stannous oxide and stannic oxide.

FIG. 2 shows the photoelectron spectra of catalyst A in preparative example 1 and catalyst G in preparative comparative example 1.

Fig. 3 is a raman spectrum of catalyst a in preparative example 1, catalyst G in preparative comparative example 1, and stannous oxide.

FIG. 4 is a scanning electron micrograph of stannous oxide.

FIG. 5 is a scanning electron micrograph of catalyst A from preparation example 1.

Fig. 6 is a scanning electron micrograph of catalyst G prepared in comparative example 1.

Figure 7 is an XRD pattern of stannous oxide.

Fig. 8 is an XRD pattern of catalyst J in preparation comparative example 4.

Fig. 9 is an XRD pattern of catalyst E in preparative example 5.

Detailed Description

The present invention will be described in detail with reference to the following embodiments, but it should be understood that the scope of the present invention is not limited by these embodiments and the principle of the present invention, but is defined by the claims.

In the present invention, anything or matters not mentioned is directly applicable to those known in the art without any change except those explicitly described. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are considered part of the original disclosure or original description of the present invention, and should not be considered as new matters not disclosed or contemplated herein, unless a person skilled in the art would consider such combination to be clearly unreasonable.

All of the features disclosed in this invention can be combined in any combination and these combinations should be understood as disclosed or described herein unless a person skilled in the art would consider the combination to be clearly unreasonable, for example in the present invention, a combination of "any range of molar ratios of silicon to tin" and "any range of tin content in the catalyst" should be considered as specifically disclosed and described herein. The numerical points disclosed in the present specification include not only the numerical points specifically disclosed in the examples but also the endpoints of each numerical range in the specification, and ranges in which any combination of the numerical points is disclosed or recited should be considered as ranges of the present invention.

Technical and scientific terms used herein are to be defined only in accordance with their definitions, and are to be understood as having ordinary meanings in the art without any definitions.

In the present invention, "optionally" means including or not including, for example, "optionally a" means including a or not including a.

In the present invention, the inert gas means a gas having no adverse effect on the performance of the catalyst.

In the catalyst of the invention, the sum of the contents of all the components is 100%.

The invention provides a preparation method of dicarboxylic acid diol ester, which comprises the following steps: in the presence of a catalyst, an aliphatic dicarboxylic acid is contacted with a monohydric alcohol for reaction, and simultaneously, water generated in the reaction is removed; the catalyst is a bulk phase catalyst containing silicon, tin and oxygen and contains Sn-O-Si bonds; the monohydric alcohol has a structure shown in a formula R-OH, wherein R is unsubstituted alkyl or alkyl containing ether bonds.

According to the invention, the monoalcohol may be a C6-C14 alkanol, preferably n-butanol, n-hexanol, n-octanol, isooctanol, n-decanol, isodecanol, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, diethylene glycol ethyl butyl ether, dipropylene glycol methyl ether or dipropylene glycol tert-butyl ether.

According to the invention, the aliphatic dicarboxylic acid can be one or more of dicarboxylic acids of C6-C14, preferably 1, 6-adipic acid, 1, 8-suberic acid, 1, 9-azelaic acid or 1, 10-sebacic acid.

According to the invention, the diol esters of dicarboxylic acids are preferably diisodecyl adipate, dioctyl azelate, dibutyl sebacate, dioctyl sebacate or diisooctyl sebacate.

According to the invention, the reaction is generally carried out under reflux for 2 to 10 hours, preferably for 3 to 5 hours.

According to the invention, the molar ratio of acid to alcohol is (1: 2) to (1: 4), preferably (1: 2.4) to (1: 3).

According to the present invention, as a means for adjusting the amount of reflux and/or a means for protecting the reaction system, an inert gas such as nitrogen or argon may be introduced into the reactor simultaneously with the reaction.

According to the present invention, if the reaction raw material alcohol azeotropes with water, the reaction raw material alcohol itself may be used as a water-carrying agent without additionally adding a water-carrying agent.

According to the invention, if a water-carrying agent is used, it can be benzene, toluene, xylene, cyclohexane, methylcyclohexane, petroleum ether or di-n-butyl ether. The dosage of the water-carrying agent can be 10-50% of the total mass of the reactants, and preferably 20-30% of the total mass of the reactants.

According to the invention, the amount of the catalyst is 0.1-10%, preferably 0.5-2% of the total mass of the reactants.

According to the invention, the method further comprises: after the reaction has ended, the catalyst is separated off and used repeatedly in the process.

According to the invention, the method further comprises: after the reaction is finished, a step of removing light components and a step of decoloring by reduced pressure distillation. In the decoloring step, an activated carbon adsorption mode is preferably adopted, and the adsorption temperature can be 90-120 ℃, and is preferably 100-110 ℃; the adsorption time may be 1 to 4 hours, preferably 2 to 3 hours.

According to the invention, the catalyst is a bulk catalyst containing silicon, tin and oxygen and contains Sn-O-Si bonds, preferably a bulk catalyst consisting of silicon, tin and oxygen and containing Sn-O-Si bonds.

According to the present invention, the catalyst may contain, as an optional component, an element other than tin. These elements are not particularly limited in the present invention and may be incorporated in the preparation of the catalyst as long as they do not have a significant adverse effect or other benefit on the catalyst performance, including but not limited to one or more of aluminum, titanium, zirconium, tin, zinc, magnesium, antimony, and bismuth.

According to the present invention, impurities may be contained in the catalyst as long as the kind and content thereof do not significantly degrade the catalyst performance. Generally, the catalyst of the present invention has a sodium mass fraction of less than 0.03% based on sodium oxide.

In contrast to the prior art, the catalyst is a bulk catalyst. The results of XPS analysis show that making bulk catalysts leads to the generation of new tin species, thereby improving the performance of tin catalysts. Because the bulk phase catalyst does not use the traditional carrier, the limit of the load capacity and the active component distribution of the supported catalyst can be broken through, so that the catalyst can have lower silicon-tin molar ratio, the catalytic activity, the selectivity and the stability of the tin catalyst are still improved, and the catalyst is easy to separate from a reaction product; the catalyst can also have a high silicon-tin molar ratio (1-22), and the catalyst has better stability and is easier to separate from a reaction product. The molar ratio of silicon to tin is not particularly limited in the present invention, and one skilled in the art can easily select an appropriate molar ratio of silicon to tin in the light of the teachings of the present invention.

According to the present invention, the molar ratio of silicon to tin in the catalyst may be 0.5 to 22, preferably 0.8 to 6, more preferably 1 to 5, and still more preferably 1.5 to 5.

According to the present invention, the mass fraction of tin in the catalyst may be 8% to 72%, preferably 23% to 65%, more preferably 26% to 61%, and still more preferably 26% to 53%.

According to the invention, the valence of the tin in the catalyst may be divalent and/or tetravalent, preferably divalent.

According to the present invention, it is preferred that in the XRD pattern of the catalyst, there are no peaks characteristic to tin oxide crystals, i.e., there are no peaks characteristic to tin oxide crystals and stannous oxide crystals. The catalyst is roasted for 3 hours at 500 ℃ under the protection of nitrogen, and an XRD (X-ray diffraction) spectrum of the catalyst has no sharp crystal characteristic peak between 5 degrees and 70 degrees; the existing silica gel supported tin catalyst has sharp crystal characteristic peak in the range after being treated under the same conditions.

According to the invention, the catalyst is an amorphous solid as can be seen from the XRD pattern of the catalyst.

Under the protection of nitrogen, after the catalyst is calcined at 300 ℃ for 3 hours, the Raman spectrum of the catalyst is 237cm^-1There is one nearbyA characteristic peak; the existing silica gel supported tin catalyst does not have the characteristic peak nearby or has the characteristic peak of 110cm after being treated under the same conditions^-1Characteristic peaks nearby and 211cm^-1The characteristic peaks in the vicinity are smaller than the characteristic peaks having smaller relative intensities. Wherein, the relative intensities of the two characteristic peaks are compared according to the peak area sizes of the two characteristic peaks, the relative intensity of the characteristic peak with a large peak area is larger, and the relative intensity of the characteristic peak with a small peak area is smaller.

According to the invention, it is preferred that the Raman spectrum of the catalyst is at 110cm^-1Near and 211cm^-1There is no characteristic peak nearby.

In one case, the catalyst is calcined at 300 ℃ for 3h under the protection of nitrogen, and the Raman spectrum of the catalyst is 110cm^-1Near and 211cm^-1No characteristic peak is nearby; the existing silica gel supported tin catalyst is treated under the same conditions and is 110cm^-1Near and 211cm^-1And each has a distinct characteristic peak nearby.

In another case, the catalyst is calcined at 300 ℃ for 3h under the protection of nitrogen, and the Raman spectrum of the catalyst is 110cm^-1Near and 211cm^-1There is a characteristic peak nearby, but the characteristic peak is 237cm^-1The relative intensity is small compared with the characteristic peak nearby (such as 110 cm)^-1Near and 211cm^-1There is a characteristic peak near each, any one of the characteristic peaks is at 237cm^-1The peak area ratios of nearby characteristic peaks are all less than 1/2); the existing silica gel supported tin catalyst is treated under the same conditions, if the concentration is 237cm^-1A characteristic peak exists nearby, and is 110cm^-1Near and 211cm^-1Any characteristic peak appearing nearby has large relative intensity compared with the characteristic peak, and the ratio of peak areas is far larger than 1.

The invention provides a preparation method of the catalyst, which comprises the steps of coprecipitating tin salt and silicate dissolved in water; in said water, with or without dissolved acid (preferably mineral acid such as hydrochloric acid, sulfuric acid or nitric acid); in the water, a metal salt other than tin is dissolved or not dissolved.

In the preparation method of the catalyst, the coprecipitation mode is not particularly limited, and any suitable mode can be adopted. For example, the aqueous solution of the tin salt may be added to the aqueous solution of the silicate, the aqueous solution of the silicate may be added to the aqueous solution of the tin salt, the aqueous solution of the silicate and the aqueous solution of the tin salt may be directly mixed or mixed by dropping them at the same time, and then the mixture may be completely precipitated. If an acid is added, it is preferable to add the acid to the aqueous tin salt solution and then mix the aqueous tin salt solution with the aqueous silicate solution; if other metal salts are added, it is also preferable to add the other metal salts to the aqueous solution of tin salt and then mix the aqueous solution of tin salt with the aqueous solution of silicate; if the acid and the other metal salt are added simultaneously, it is preferable to add both the acid and the other metal salt to the aqueous tin salt solution and then impregnate the carrier with the aqueous tin salt solution.

In the preparation method of the catalyst, the silicate is generally one or more of sodium silicate and potassium silicate.

In the preparation method of the catalyst, the tin salt is generally one or more of stannous chloride (including anhydrous stannous chloride or stannous chloride dihydrate), stannic chloride (including anhydrous stannic chloride or stannic chloride pentahydrate) and stannous sulfate.

In the preparation method of the catalyst, the molar ratio of silicon to tin is 0.5-22, preferably 0.8-6, more preferably 1-5, and even more preferably 1.5-5.

In the method for preparing the catalyst, the silicate and the tin salt are respectively used in the molar amount of silicon atoms and tin atoms, the acid is used in the molar amount capable of releasing protons, and the silicate, the tin salt and the acid preferably satisfy the following relational expressions: m_Si-M_Sn＝2×M_Proton(s)。

In the preparation method of the catalyst, the kind and amount of the other metal salt are not particularly limited, and an appropriate amount of the other metal salt may be introduced in the preparation of the catalyst as long as there is no significant adverse effect or other benefit on the catalyst performance. The other metal salt is preferably one or more selected from aluminum salt, titanium salt, zirconium salt, tin salt, zinc salt, magnesium salt, antimony salt and bismuth salt.

In the preparation method of the catalyst, the temperature of coprecipitation is generally about room temperature (for example, 25 ℃ to 40 ℃).

The preparation method of the catalyst also comprises the operation of adjusting the pH value of the water phase after the reactants are mixed. The pH value of the water phase is generally adjusted to 2-12, preferably 4-8, and more preferably 4-7. The invention has no special limitation on the medicament and the mode for adjusting the pH value of the water phase, and the pH value of the system can be adjusted by using the common alkaline aqueous solution, such as NaOH aqueous solution, KOH aqueous solution or ammonia aqueous solution.

In the preparation method of the catalyst, after coprecipitation, the precipitate is preferably kept in water for a period of time, generally 0.1 to 8 hours (preferably 0.5 to 5 hours); the temperature maintained in the water is generally from 25 ℃ to 70 ℃, preferably the temperature at which precipitation takes place.

In the process for the preparation of the catalyst, the precipitate can be easily separated from the aqueous phase by filtration.

In the preparation method of the catalyst, the precipitate is preferably washed (generally washed with water), heat-treated, and then the catalyst of the present invention is obtained.

In the preparation method of the catalyst, the temperature of the heat treatment is generally 80-600 ℃, preferably 200-500 ℃, and more preferably 250-350 ℃. The heat treatment is preferably carried out under the protection of an inert gas, such as nitrogen or argon. The time for the heat treatment is generally 2 to 5 hours, preferably 3 to 5 hours.

Examples section

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

In the context of the present specification, all medicaments and raw materials are either commercially available or can be manufactured according to established knowledge. In the following examples and comparative examples, all reagents used were analytical reagents unless otherwise specified.

In the context of the present specification, including the following examples and comparative examples, the stannous oxide in the tests and analyses was subjected to a "calcination at 200 ℃ for 3 hours under nitrogen atmosphere" treatment unless otherwise specified; the tin oxide in the test and analysis was treated by "baking at 500 ℃ for 3 hours under nitrogen atmosphere" unless otherwise specified.

In the context of the present description, including the examples and comparative examples below, X-ray photoelectron spectroscopy (XPS) uses an X-ray photoelectron spectrometer of the model ESCALB 220i-XL, manufactured by VG Scientific, Inc. (test conditions: the excitation light source is monochromatized Al K alpha X-ray, the power is 300W, and the basic vacuum is 3X 10^-9mbar, electron binding energy was corrected by the C1s peak of elemental carbon. ).

In the context of the present specification, including the following examples and comparative examples, X-ray fluorescence spectroscopy (XRF) quantitative and semi-quantitative analysis of element content was carried out by external standard method using a 3271E type X-ray fluorescence spectrometer manufactured by Nippon Denshi electric motors industries, Ltd, to detect the line intensity with a scintillation counter and a proportional counter (test conditions: powder tablet molding, rhodium-palladium, excitation voltage 50kV, and excitation current 50 mA).

In the context of the present specification, including the examples and comparative examples below, atomic emission spectrometry (ICP-AES) was performed using an Atom Scan model 16 inductively coupled plasma emission spectrometry, USA (test conditions: dissolution of the catalyst in a solution of HCl to HF volume ratio of 50:1, digestion using a microwave digestion instrument manufactured by CEM, USA.).

In the context of the present description, including the following examples and comparative examples, Raman spectroscopy was performed using a LAM-800 laser confocal Raman spectrometer (test conditions: incident light of 532nm, resolution of 4 cm) from JY, France^-1The scanning range is 100-1200 cm^-1)。

In the context of the present specification, including the following examples and comparative examples, Scanning Electron Microscopy (SEM) employed a Quanta 200F scanning electron microscope manufactured by FEI corporation (test conditions: drying of the sample followed by vacuum evaporation of the metal spray to increase conductivity and contrast, analytical electron microscope acceleration voltage of 20.0KV, magnification of 1-30 k).

In the context of the present specification, including the following examples and comparative examples, X-ray powder diffraction (XRD) was carried out using an X-ray diffractometer model D5005 (test conditions: Cu target, Ka radiation, Ni filter, tube voltage 35kV, tube current 45mA, scanning range 2 θ 5-70 °) manufactured by Siemens of Germany.

In the context of the present specification, including the following examples and comparative examples, the method of calculating the esterification rate is as follows:

the acid value in the esterification rate calculation method is determined by the method specified in GB-1668-2008-T.

In the context of the present specification, including the following examples and comparative examples, the esterification reaction selectivity was determined using an Agilent 7890A gas chromatograph, usa, under chromatographic conditions: capillary column (50m × 0.2mm × 0.5 μm), FID detector, detection chamber temperature of 280 deg.C, column temperature programmed from 60 deg.C to 260 deg.C, gasification chamber temperature of 280 deg.C, hydrogen flow rate of 30mL/min, air flow rate of 400mL/min, and nitrogen pressure of 10 MPa.

The calculation method is as follows:

preparation of example 1

2.26g of stannous chloride dihydrate (SnCl)₂·2H₂O) was dissolved in 10ml of deionized water, Na was taken₂O·SiO₂·9H₂O is dissolved in deionized water. Adding the two solutions into a flask at 30 ℃, simultaneously adding the feeding Si/Sn ratio of 1, adding an ammonia water solution to adjust the pH value to 6, after complete precipitation, continuously keeping the temperature at 50 ℃ for 2 hours, filtering, washing with water, drying at 80 ℃, and then roasting at 300 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst, namely the number A.

The catalyst had a Si/Sn molar ratio of 0.96 by XRF analysis.

XPS analysis shows that the mass fraction of tin atoms on the surface of the catalyst is 5.12%; by ICP analysis, the mass fraction of tin in the catalyst was 63.5%.

Preparation of example 2

2.26g of stannous chloride dihydrate (SnCl)₂·2H₂O) was dissolved in 80ml of a 1mol/L hydrochloric acid aqueous solution, and Na was taken out₂O·SiO₂·9H₂O is dissolved in deionized water. Adding the two solutions into a flask at 30 ℃ simultaneously, regulating the pH value to 7 by adding an ammonia water solution with the feeding Si/Sn ratio of 5, continuously keeping the solution at 30 ℃ for 2 hours after the precipitation is completed, filtering, washing, drying at 80 ℃, and roasting at 250 ℃ for 4 hours under the protection of nitrogen to obtain the tin catalyst, namely the number B.

By ICP analysis, the mass fraction of tin in the catalyst was 27.2%.

Preparation of example 3

Dissolving 2.15g stannous sulfate in 10ml deionized water, and taking Na₂O·SiO₂·9H₂O is dissolved in deionized water. Adding the two solutions into a flask at 30 ℃ simultaneously, regulating the pH value to 7 by adding an ammonia water solution with the feeding Si/Sn ratio of 1, continuously keeping the solution at 30 ℃ for 4 hours after complete precipitation, filtering, washing, drying at 80 ℃, and roasting at 300 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst, namely the number C.

The catalyst had a Si/Sn molar ratio of 0.99 by XRF analysis.

By ICP analysis, the mass fraction of tin in the catalyst was 61.2%.

Preparation of example 4

Dissolving 2.15g stannous sulfate in 40ml 1mol/L hydrochloric acid water solution, and collecting K₂O·SiO₂Dissolved in deionized water. Adding the two solutions into a flask at 30 ℃ simultaneously, regulating the pH value to 7 by adding an ammonia water solution with the feeding Si/Sn ratio of 3, continuously keeping the solution at 30 ℃ for 2 hours after the precipitation is completed, filtering, washing, drying at 80 ℃, and roasting at 250 ℃ for 4 hours under the protection of nitrogen to obtain the tin catalyst, namely the number D.

The catalyst had a Si/Sn molar ratio of 3.02 by XRF analysis.

By ICP analysis, the mass fraction of tin in the catalyst was 37.3%.

Preparation of example 5

2.26g of stannous chloride dihydrate (SnCl)₂·2H₂O) is dissolved in 80ml of hydrochloric acid aqueous solution with the concentration of 1mol/L, K is taken₂O·SiO₂Dissolved in deionized water. Adding the two solutions into a flask at 30 ℃ simultaneously, regulating the pH value to 7 by adding an ammonia water solution with the feeding Si/Sn ratio of 5, continuously keeping the solution at 30 ℃ for 4 hours after complete precipitation, filtering, washing, drying at 80 ℃, and roasting at 500 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst, namely the number E.

By ICP analysis, the mass fraction of tin in the catalyst was 27.1%.

Preparation of example 6

3.51g of tin tetrachloride pentahydrate (SnCl) are taken₄·5H₂O) was dissolved in 10ml of deionized water, Na was taken₂O·SiO₂·9H₂O is dissolved in deionized water. Adding the two solutions into a flask at 30 ℃, simultaneously adding the feeding Si/Sn ratio of 2, adding an ammonia water solution to adjust the pH value to 7, continuously keeping the solution at 50 ℃ for 0.5 hour after the precipitation is completed, filtering, washing, drying at 80 ℃, and roasting at 200 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst, wherein the number of the tin catalyst is F.

By ICP analysis, the mass fraction of tin in the catalyst was 44.0%.

Preparation of comparative example 1

5g of stannous chloride dihydrate (SnCl)₂·2H₂O) to SnCl₂Adding 10G of silica gel into 10 mass percent of aqueous solution, stirring for 10 hours, adding 20 mass percent of ammonia aqueous solution into the aqueous solution, uniformly stirring, washing, filtering, drying, and roasting at 300 ℃ for 3 hours under the protection of nitrogen to obtain the comparative tin catalyst, wherein the number G is the number G.

By ICP analysis, the mass fraction of tin in the catalyst was 20.1%.

Preparation of comparative example 2

The catalyst was prepared by the same method as that for the preparation of comparative example 1, except that: stannous chloride dihydrate (SnCl)₂·2H₂O) was used in an amount of 4 g. The catalyst number is H.

By ICP analysis, the mass fraction of tin in the catalyst was 16.4%.

Preparation of comparative example 3

The catalyst was prepared by the same method as that for the preparation of comparative example 1, except that: stannous chloride dihydrate (SnCl)₂·2H₂O) was used in an amount of 7 g. The catalyst is numbered I.

By ICP analysis, the mass fraction of tin in the catalyst was 25.3%.

Preparation of comparative example 4

The catalyst was prepared by the same method as that for the preparation of comparative example 1, except that: calcining at 500 deg.C for 3 hr under nitrogen protection. Catalyst number J.

By ICP analysis, the mass fraction of tin in the catalyst was 20.1%.

Reaction example 1

This example illustrates the effect of preparing di-n-butyl adipate from adipic acid and n-butanol as starting materials.

In the reaction system, the molar ratio of adipic acid to n-butanol is 1:3, and a catalyst accounting for 1.5 percent of the total mass of reactants is added. Introducing nitrogen, heating to reflux, refluxing and water distributing during the reaction, and stirring for reaction for 3 hours. After the reaction is finished, stopping stirring, standing for 10 minutes, sampling, observing an upper liquid phase, and separating a liquid phase product from the catalyst. And (5) analyzing the liquid phase product, and calculating the esterification rate and the selectivity.

The reaction results are shown in Table 1.

Reaction example 2

This example serves to illustrate the comparative effect of the catalyst, supported catalyst and stannous oxide of the present invention on reuse.

The procedure of reaction example 1 was followed except that: except for using the catalyst A, G and stannous oxide in the first reaction, the catalyst recovered in the last reaction is reused in the catalyst of each subsequent reaction; wherein, the series test of the catalyst A adopts a filtration mode to recover, and the series test of the catalyst G and the stannous oxide adopts a centrifugation mode to recover the catalyst due to the difficult filtration and the loss of the catalyst.

The reaction results are shown in Table 2.

Reaction example 3

The procedure of reaction example 1 was followed except that: the molar ratio of adipic acid to n-butanol was 1:2.6 and the reaction time was 5 hours. After the reaction is finished, separating the liquid phase product from the catalyst, and analyzing the liquid phase product. From the analysis results, the esterification rate of the reaction was 99.45%, and the selectivity of the reaction was 98.59%.

And removing excessive alcohol from the liquid phase product by reduced pressure distillation, stirring and adsorbing for 2 hours (decoloring) by using activated carbon at 100 ℃, and filtering to obtain a transparent oily liquid product.

Reaction example 4

The procedure of reaction example 1 was followed except that: the molar ratio of adipic acid to n-butanol was 1:3, the amount of catalyst was 1% of the total mass of the reactants, and the reaction time was 5 hours. After the reaction is finished, separating the liquid phase product from the catalyst, and analyzing the liquid phase product. From the analysis results, the esterification rate of the reaction was 99.50%, and the selectivity of the reaction was 98.87%.

Reaction example 5

The procedure of reaction example 1 was followed except that: sebacic acid and n-butyl alcohol are used as raw materials to prepare the di-n-butyl sebacate, the molar ratio of the sebacic acid to the n-butyl alcohol is 1:3, the dosage of the catalyst is 1.5 percent of the total mass of reactants, and the reaction time is 4 hours. After the reaction is finished, separating the liquid phase product from the catalyst, and analyzing the liquid phase product. From the analysis results, the esterification rate of the reaction was 99.56%, and the selectivity of the reaction was 99.23%.

TABLE 1

Catalyst and process for preparing same	Degree of esterification/%)	Selectivity/%)	Upper liquid phase
				A	99.80	99.77	Clear and bright
B	99.62	99.40	Clear and bright
				C	99.70	99.42	Clear and bright
D	99.73	99.64	Clear and bright
				E	98.58	99.21	Clear and bright
F	98.96	98.32	Clear and bright
				G	99.45	99.23	Slight turbidity
H	99.11	98.83	Slight turbidity
				I	99.21	99.03	Slight turbidity
J	98.66	98.31	Slight turbidity
				Stannous oxide	99.42	99.45	Is relatively turbid

TABLE 2

As can be seen from FIG. 1, the binding energy of tin in stannous oxide is at 486.31ev and that of tin in stannic oxide is at 486.53 ev. As can be seen from FIG. 2, the binding energy of tin in the silica-supported catalyst is at 487.89ev, and the binding energy of tin in the catalyst of the present invention is at 488.31 ev. As can be seen from fig. 1 and 2, the binding energy of tin is highest in the catalyst of the present invention.

As can be seen from FIG. 3, at 110cm^-1Near and 211cm^-1Nearby, the supported catalyst and stannous oxide have two characteristic peaks which are consistent, while the catalyst of the invention does not have the two characteristic peaks, but is at 237cm^-1In the vicinity, the catalyst of the present invention has a strong characteristic peak which is not present in both the supported catalyst and the stannous oxide.

As can be seen from fig. 4, stannous oxide (purchased and untreated) is a cuboid particle with a single morphology. As can be seen from fig. 5, the catalyst of the present invention has no clear outline, is clustered together, and is a uniform-appearing substance. As can be seen from fig. 6, in the supported catalyst, the carrier was clearly visible and was a substance having a non-uniform appearance.

As can be seen from fig. 7, 8 and 9, a plurality of sharp crystal characteristic peaks exist between the conventional supported tin catalyst (calcined at 500 ℃ for 3 hours under the protection of nitrogen) and stannous oxide at 5 ° to 70 °, whereas the catalyst of the present invention has no sharp crystal characteristic peak at 5 ° to 70 °.

Claims

1. A method for preparing diol dicarboxylic acid ester comprises the following steps: in the presence of a catalyst, an aliphatic dicarboxylic acid is contacted with a monohydric alcohol for reaction, and simultaneously, water generated in the reaction is removed; the catalyst is a bulk phase catalyst consisting of silicon, tin and oxygen and contains Sn-O-Si bonds; in the XRD pattern of the catalyst, no characteristic peak of tin oxide crystal exists; the monohydric alcohol has a structure shown in a formula R-OH, wherein R is unsubstituted alkyl or alkyl containing ether bonds.

2. The process according to claim 1, wherein the aliphatic dicarboxylic acid is one or more dicarboxylic acids selected from the group consisting of C6-C14.

3. The process according to claim 2, wherein the aliphatic dicarboxylic acid is 1, 6-adipic acid, 1, 8-suberic acid, 1, 9-azelaic acid or 1, 10-sebacic acid.

4. The process according to claim 1, wherein the monohydric alcohol is n-butanol, n-hexanol, n-octanol, isooctanol, n-decanol, isodecanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl butyl ether, dipropylene glycol monomethyl ether or dipropylene glycol mono-t-butyl ether.

5. The process according to claim 1, wherein the reaction is carried out under reflux for 3 to 5 hours.

6. The process of claim 1, wherein the molar ratio of alcohol to acid is 2.4: 1-3: 1.

7. the process according to claim 1, wherein the catalyst is used in an amount of 0.5 to 2% by mass based on the total mass of the reactants.

8. The method of claim 1, further comprising: after the reaction is finished, a step of removing light components by reduced pressure distillation and a step of decoloring.

9. The process according to claim 1, wherein the molar ratio of silicon to tin in the catalyst is 0.8 to 6.

10. The method according to claim 9, wherein the molar ratio of silicon to tin in the catalyst is 1.5 to 5.

11. The process according to claim 1, wherein the mass fraction of tin in the catalyst is 23 to 65%.

12. The process according to claim 1, wherein the valence of tin in the catalyst is divalent or tetravalent.

13. The method according to claim 1, wherein the catalyst has a Raman spectrum of 237cm^-1A characteristic peak is present in the vicinity.

14. The method according to claim 1, wherein the catalyst has a Raman spectrum of 110cm^-1Near and 211cm^-1There is no vibration peak or a characteristic peak with relatively small intensity in the vicinity.

15. The process according to claim 1, wherein the catalyst is an amorphous solid.

16. A process according to claim 1, wherein the catalyst is separated off after the end of the reaction and is reused in the process.

17. A method for processing a plastic, characterized in that a dicarboxylic acid diol ester is produced by the method according to any one of claims 1 to 16, and the dicarboxylic acid diol ester is used as a plasticizer.