CN110152648A - Preparation method of tin catalyst, tin catalyst and application thereof - Google Patents

Abstract

The present invention relates to the preparation method of tin catalyst, tin catalyst and its application, catalyst therein contains Sn-O-Si key；In its Raman spectrum, in 237cm^‑1Nearby there are a characteristic peaks, and in 110cm^‑1Neighbouring and 211cm^‑1There is no characteristic peak nearby or there are the lesser characteristic peaks of relative intensity.Catalyst of the invention is suitable for the esterification or alcohol of catalytic alcohol and carboxylic acid and the ester exchange reaction of carboxylate, has high catalytic activity and selectivity, and can keep good catalytic performance for a long time.

Description

Preparation method of tin catalyst, tin catalyst and application thereof

technical field

The invention relates to a preparation method of a tin catalyst, a tin catalyst and an application thereof.

Background technique

Esterification is one of the most important organic reactions, and its products are widely used in various fields of chemical industry. Esterification generally requires the use of catalysts, which can be divided into acidic catalysts and non-acidic catalysts. Acidic catalysts are some inorganic acids and organic acids. The main disadvantage is poor reaction selectivity. In addition, there are problems such as corrosion, pollution, catalysts that cannot be recycled and reused, and product post-processing difficulties. Non-acidic catalysts are mainly metal compounds such as aluminum, titanium, zirconium, tin, zinc, magnesium, antimony, bismuth, etc. These compounds can be used alone or made into composite catalysts, which are generally non-corrosive and relatively selective in reaction. higher. Titanate is a non-acidic homogeneous catalyst. Although it has high catalytic activity, it needs to be decomposed to remove the catalyst from the reaction product, which causes difficulties in the post-processing of the product. As an esterification catalyst, stannous oxide has high catalytic activity, but when stannous oxide catalyzes alkyd esterification reaction, the catalyst is easy to refine and deactivates quickly, which is not conducive to the long-term operation and intermittent esterification of the continuous esterification process Process catalysts are reused.

CN1760339A, CN1740277A disclose the supported catalyst of divalent tin, and it is used for the esterification decarboxylation of high-acid crude oil or distillate oil. US3520915 also discloses a supported catalyst of divalent tin, which catalyst is used to prepare unsaturated fatty nitriles. Wenlei Xie etc. disclose the supported catalyst of tetravalent tin, and its catalyst is used for the transesterification reaction of soybean oil (Silica-Supported Tin Oxides as Heterogeneous Acid Catalysts for Transesterification of Soybean Oil with Methanol, Ind.Eng.Chem.Res.2012, 51, 225–231). None of these catalysts can well solve the problem of catalyst refinement and deactivation. Vinicius etc. disclose the composite oxide of aluminum and divalent tin, and use it for the esterification reaction of soybean oil fatty acid, the result shows that "compared with stannous oxide, the catalytic activity of composite oxide reduces" (Metal oxides as heterogeneous catalysts foresterification of fatty acids obtained from soybean oil, Fuel Processing Technology, 2011, 92, 53–57). Zhang Yuanzhuo etc. disclose a kind of silicon dioxide immobilized organotin catalyst, and it is used for the reaction of dimethyl carbonate and phenol (the influence of silanol on the silicon dioxide immobilized organotin transesterification catalytic performance, Chemical Industry Journal, Vol.68 No.5, 1892-1898).

Contents of the invention

One of the objectives of the present invention is to provide a tin catalyst and its application, the catalyst has higher catalytic activity, selectivity and better stability when catalyzing the esterification reaction of alcohol and carboxylic acid.

The second object of the present invention is to solve the refinement problem of existing tin catalysts.

The third object of the present invention is to provide a preparation method of tin catalyst.

Specifically, the present invention mainly includes the following contents:

1. a preparation method of tin catalyst, is characterized in that, comprises in the presence of carrier, carries out the step of co-precipitation to water-soluble tin salt and silicate; In described water, be dissolved with or undissolved acid (preferably hydrochloric acid, sulfuric acid or nitric acid); in the water, other metal salts other than tin are dissolved or not dissolved.

2. According to the preparation method described in 1, it is characterized in that the carrier is selected from one or more of activated carbon, alumina, molecular sieves and silica gel.

3. According to any one of the above preparation methods, it is characterized in that, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt is 0.8-6 (preferably 1.5-5).

4. According to any one of the above preparation methods, it is characterized in that the feed ratio of raw materials is such that in the catalyst, the mass fraction of tin is 15% to 45% (preferably 20% to 35%).

5. According to any one of the aforementioned preparation methods, it is characterized in that the other metal salts are selected from one or more of aluminum salts, titanium salts, zirconium salts, tin salts, zinc salts, magnesium salts, antimony salts and bismuth salts. kind.

6. According to any one of the aforementioned preparation methods, it is characterized in that the tin salt is selected from one or more of stannous chloride, tin tetrachloride and stannous sulfate.

7. According to any one of the above preparation methods, it is characterized in that the silicate is selected from one or more of sodium silicate and potassium silicate.

8. The preparation method according to any one of the above, characterized in that it includes the operation of adjusting the pH value of the aqueous phase (generally, the pH value of the aqueous phase is adjusted to 2-12, preferably 4-8, more preferably 4-7).

9. According to any one of the aforementioned preparation methods, it is characterized in that it also includes the step of heat treatment at 80°C to 600°C (preferably 200°C to 500°C, more preferably 250°C to 350°C) (the heat treatment is preferably carried out under inert gas under protection).

10. A method for preparing a tin catalyst, comprising: (1) a step of impregnating a support with an aqueous solution of tin salts, optional acids and other metal salts; and (2) silicic acid The step of treating the carrier obtained in (1) with salt.

11. The preparation method according to 10, wherein the carrier is selected from one or more of activated carbon, alumina, molecular sieve and silica gel.

12. The preparation method according to 10 or 11, characterized in that, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt is 0.8-6 (preferably 1.5-5).

13. According to any one of 10 to 12, the preparation method is characterized in that the feed ratio of the raw materials is such that the mass fraction of tin in the catalyst is 15% to 45% (preferably 20% to 35%).

14. According to the preparation method according to any one of 10-13, it is characterized in that the other metal salts are selected from one of aluminum salts, titanium salts, zirconium salts, tin salts, zinc salts, magnesium salts, antimony salts and bismuth salts species or several.

15. The preparation method according to any one of 10-14, wherein the tin salt is selected from one or more of stannous chloride, tin tetrachloride and stannous sulfate.

16. The preparation method according to any one of 10-15, wherein the silicate is selected from one or more of sodium silicate and potassium silicate.

17. The preparation method according to any one of 10-16, characterized in that it includes the operation of adjusting the pH value of the aqueous phase (generally, the pH value of the aqueous phase is adjusted to 2-12, preferably 4-8, more preferably 4-7).

18. The preparation method according to any one of 10 to 17, characterized in that it includes the step of heat treatment at 80°C to 600°C (preferably 200°C to 500°C, more preferably 250°C to 350°C) (the heat treatment is preferably at under the protection of inert gas).

19. A tin catalyst, characterized in that it is obtained by any one of the aforementioned preparation methods.

20. An inorganic tin catalyst, characterized in that the catalyst contains Sn-O-Si bonds; and under the protection of nitrogen, after the catalyst is roasted at 500°C for 3 hours, there are no tin oxide crystals and sub-oxide crystals in its XRD spectrum. Characteristic peaks of tin crystals.

21. The catalyst according to any one of the above, characterized in that, after the catalyst is calcined at 300°C for 3 hours under the protection of nitrogen, in its Raman spectrum, there is a characteristic peak around 237cm ^-1 , and a characteristic peak around 110cm ^-1 and around 211cm ^-1 there are no characteristic peaks or there are characteristic peaks with relatively small intensity.

22. A tin catalyst, characterized in that the catalyst contains Sn ^- O-Si bonds; and under the protection of nitrogen, after the catalyst is calcined at 300°C for 3 hours, in its Raman spectrum, there is a There are no characteristic peaks around 110cm ^-1 and 211cm ^-1 or there are characteristic peaks with relatively small intensity.

23. The catalyst according to any one of the foregoing, characterized in that, in the catalyst, the valence state of tin is divalent or tetravalent.

24. Catalyst according to any one of the preceding, characterized in that said catalyst is an amorphous solid.

25. The catalyst according to any one of the foregoing, characterized in that the catalyst contains a carrier (the carrier is preferably selected from one or more of activated carbon, alumina, molecular sieve and silica gel).

26. Use of any one of the aforementioned catalysts in catalyzing the esterification reaction of alcohols with carboxylic acids or the transesterification reaction of alcohols with carboxylic acid esters.

27. A method for producing carboxylate by the reaction of alcohol and carboxylic acid, characterized in that any of the aforementioned catalysts is used.

28. The method according to 26 or 27, characterized in that it comprises the step of separating the catalyst after the reaction and reusing the catalyst for the reaction.

In the prior art, stannous oxide is a better non-acidic esterification catalyst, but the catalyst has the problem of rapid deactivation, and more seriously, the catalyst is easy to refine, which makes it difficult to separate the catalyst from the reaction product. It brings great difficulties to actual production, and the prior art cannot ideally solve these problems by loading or making composite metal oxides. The present inventor discovered unexpectedly in the experiment, carry out co-precipitation with silicate and tin salt, can make the high-temperature esterification catalyst with higher activity, better selectivity and no refinement; Also unexpectedly, this The tetravalent tin catalyst obtained by the method also has good activity, selectivity and thermal stability. As a result of this finding, the present inventors proposed and completed the present invention.

Contain new tin species in the catalyzer of the present invention, and combine more firmly between silicon, tin, oxygen, make the catalyzer of the present invention have the following advantages: the catalyzer of the present invention has higher catalytic activity and selectivity, and can be in more Maintain good catalytic performance for a long time; the catalyst of the present invention is easy to separate from the reaction product, and the separated catalyst does not need to be activated by heating, and can still maintain good catalytic performance, thereby greatly facilitating the repeated use of the catalyst; the catalyst of the present invention is thermally It has higher stability and basically does not change at high temperature. In addition, the preparation method of the catalyst of the present invention is simple and easy for industrialization.

Other features and advantages of the present invention will be further described in detail in the detailed description.

Description of drawings

Fig. 1 is the XPS photoelectron spectrum of stannous oxide and tin dioxide.

Fig. 2 is the photoelectron spectrum of the catalyst A in the preparation example 1 and the catalyst G in the preparation comparative example 1.

Fig. 3 is the Raman spectrum of catalyst A in Preparation Example 1, catalyst G in Preparation Comparative Example 1 and stannous oxide.

Figure 4 is a scanning electron microscope image of stannous oxide.

5 is a scanning electron micrograph of catalyst A in Preparation Example 1.

FIG. 6 is a scanning electron micrograph of catalyst G prepared in Comparative Example 1.

Figure 7 is the XRD spectrum of stannous oxide.

FIG. 8 is an XRD spectrum of catalyst J prepared in Comparative Example 4.

FIG. 9 is an XRD pattern of catalyst E prepared in Example 5.

FIG. 10 is the XRD pattern of catalyst B in Preparation Example 2.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments, but it should be noted that the protection scope of the present invention is not limited by these specific embodiments and principle explanations, but is determined by the claims.

In the present invention, any matters or matters not mentioned are directly applicable to those known in the art without any change except for the contents explicitly stated. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the resulting technical solutions or technical ideas are regarded as a part of the original disclosure or original record of the present invention, and should not be It is regarded as a new content that has not been disclosed or expected in this paper, unless those skilled in the art think that the combination is obviously unreasonable.

All the features disclosed in the present invention can be combined arbitrarily, and these combinations should be understood as the content disclosed or recorded in the present invention, unless those skilled in the art think that the combination is obviously unreasonable, such as in the present invention, "the molar ratio of silicon to tin The combination of "any range" and "any range of tin content in the catalyst" should be considered as specifically disclosed and recorded by the present invention. The numerical points disclosed in this specification not only include the numerical points specifically disclosed in the examples, but also include the endpoints of the numerical ranges in the specification. Any combination of these numerical points shall be regarded as the disclosed or recorded range of the present invention .

For the technical and scientific terms in the present invention, those defined shall prevail, and those not defined shall be understood according to the common meaning in the field.

In the present invention, "optional" means including or not including, for example, "optional A" means including A or not including A.

In the present invention, an inert gas refers to a gas that does not adversely affect the performance of the catalyst.

In the catalyst of the present invention, the sum of the contents of each component is 100%.

In the present invention, "inorganic tin" means that tin is not directly linked to a hydrocarbon group or a substituted hydrocarbon group.

One, the catalyst of the present invention

The invention provides an inorganic tin catalyst, which contains Sn-O-Si bonds; and under the protection of nitrogen, after the catalyst is calcined at 500°C for 3 hours, there are no tin oxide crystals and stannous oxide crystals in its XRD spectrum characteristic peaks.

According to the inorganic tin catalyst, under the protection of nitrogen, after roasting at 500° C. for 3 h, in its XRD spectrum, there is no sharp crystal characteristic peak between 5° and 70°; while the existing silica gel supported tin catalyst, After processing under the same conditions, sharp crystal characteristic peaks appear in this range.

According to the inorganic tin catalyst, it may or may not contain a carrier.

The present invention also provides another tin catalyst, which contains Sn ^- O-Si bonds; and under the protection of nitrogen, after the catalyst is calcined at 300°C for 3 hours, in its Raman spectrum, there is a There are no characteristic peaks around 110cm ^-1 and 211cm ^-1 or there are characteristic peaks with relatively low intensity (preferably there are no characteristic peaks around 110cm ^-1 and 211cm ^-1 ). Among them, the relative intensity of two characteristic peaks is compared by their peak area, the characteristic peak with larger peak area has larger relative intensity, and the characteristic peak with smaller peak area has smaller relative intensity.

According to the described tin catalyst, under the protection of nitrogen, after the catalyst is calcined at 300°C for 3 hours, in its Raman spectrum, there is a characteristic peak near 237cm ^-1 ; After down-processing, there is no such characteristic peak near here or there are characteristic peaks with smaller relative intensities compared with the characteristic peaks near 110cm ^-1 and the characteristic peaks near 211cm ^-1 .

In one case, after the tin catalyst was calcined at 300°C for 3 hours under the protection of nitrogen, in its Raman spectrum, there were no characteristic peaks near 110cm ^-1 and 211cm ^-1 ; The catalyst, after being treated under the same conditions, has an obvious characteristic peak around 110cm ^-1 and 211cm ^-1 respectively.

In another case, after the tin catalyst is calcined at 300° C. for 3 hours under the protection of nitrogen, in its Raman spectrum, there are characteristic peaks around 110 cm ^-1 and 211 cm ^-1 , but the existing characteristic peaks are not the same as Compared with the characteristic peaks near 237cm ^-1 , the relative intensity is small (for example, there is a characteristic peak near 110cm ^-1 and 211cm ^-1 , and the peak area ratio of any characteristic peak to the characteristic peak near 237cm ^-1 are all less than 1/2); and the existing silica gel ^- supported tin catalyst, after being treated under the same conditions, if there is a characteristic ^peak around ^237cm Compared with the peaks, the relative intensity is very large, and the ratio of the peak areas is much greater than 1.

According to said tin catalyst, stannous oxide may not be contained, and a small amount of stannous oxide may also be contained.

The aforementioned two catalysts are collectively described below.

According to the catalyst of the present invention, in one embodiment, the catalyst is an amorphous solid.

The catalyst according to the present invention may contain other elements than tin as optional components. The present invention has no special restrictions on these elements, as long as these elements have no obvious adverse effect on the performance of the catalyst or have other benefits, these elements can be introduced during the preparation of the catalyst, these elements include but not limited to aluminum, titanium, zirconium , one or more of tin, zinc, magnesium, antimony and bismuth.

The catalyst according to the present invention may contain impurities as long as the type and content thereof do not significantly reduce the performance of the catalyst. Generally, in the catalyst of the present invention, based on sodium oxide, the mass fraction of sodium is lower than 0.03%.

The catalyst according to the invention may or may not contain a carrier. The carrier can be selected from one or more of activated carbon, alumina, molecular sieve and silica gel.

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

According to the catalyst of the present invention, when the catalyst does not contain a carrier, the mass fraction of tin can be 8%-72%, preferably 23%-65%, more preferably 26%-61%, even more preferably 26%-53%.

According to the catalyst of the present invention, when the catalyst contains a carrier, the mass fraction of tin can be 15%-45%, preferably 20%-35%.

According to the catalyst of the present invention, the valence state of tin can be divalent and/or tetravalent, preferably divalent.

According to the catalyzer of the present invention, the analytical result of XPS shows, silicate and tin salt reaction cause new tin species to produce, thus improved the performance of tin catalyst, make catalyzer of the present invention have better catalytic activity, selectivity and Stability, and easy separation of the catalyst from the reaction product. The present invention has no particular limitation on the molar ratio of silicon to tin. The key lies in adjusting the amount of tin-modified silicon in the catalyst preparation process. Under the guidance of this, those skilled in the art can easily select a suitable molar ratio of silicon to tin.

Two, catalyst preparation method of the present invention

The invention provides a preparation method of a tin catalyst, comprising the step of co-precipitating water-soluble tin salt and silicate in the presence of a carrier; in the water, acid (preferably hydrochloric acid, sulfuric acid) is dissolved or undissolved or nitric acid); in the water, other metal salts other than tin are dissolved or not dissolved.

According to the catalyst preparation method of the present invention, the carrier is preferably selected from one or more of activated carbon, alumina, molecular sieve and silica gel.

According to the preparation method of the catalyst of the present invention, there is no special limitation on the way of co-precipitation, and any existing suitable way can be used. For example, the aqueous solution of tin salt can be added to the aqueous solution of silicate, and the aqueous solution of silicate can also be added to the aqueous solution of tin salt, and the two can also be mixed directly or in a manner of dropping at the same time, and then made Precipitation is complete. If an acid is added, it is better to add the acid to the tin salt solution first, and then mix the tin salt solution with the silicate solution; if other metal salts are added, it is better to add the other metal salts to the tin brine solution, and then mix the tin brine solution with the silicate solution.

According to the catalyst preparation method of the present invention, the silicate is generally one or more of sodium silicate and potassium silicate.

According to the catalyst preparation method of the present invention, the tin salt is generally stannous chloride (including anhydrous stannous chloride or stannous chloride dihydrate), tin tetrachloride (comprising anhydrous tin tetrachloride or pentahydrate One or more of tin tetrachloride) and stannous sulfate.

According to the catalyst preparation method of the present invention, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt can be 0.5-22, preferably 0.8-6, more preferably 1-5, further Preferably it is 1.5-5.

According to the catalyst preparation method of the present invention, the feeding ratio of all raw materials is such that the mass fraction of tin in the catalyst is 15%-45% (preferably 20%-35%).

According to the catalyst preparation method of the present invention, the consumption of silicate and tin salt is in the molar weight of silicon atom and tin atom respectively, the consumption of acid is in the molar weight that can release proton, the consumption of silicate, tin salt and acid Preferably, the following relational formula is satisfied: M _Si -M _Sn =2×M _protons .

According to the catalyst preparation method of the present invention, there are no special restrictions on the type and amount of the other metal salts, as long as there is no obvious adverse effect on the catalyst performance or other benefits, an appropriate amount of other metal salts. The other metal salts are preferably selected from one or more of aluminum salts, titanium salts, zirconium salts, tin salts, zinc salts, magnesium salts, antimony salts and bismuth salts.

According to the catalyst preparation method of the present invention, the co-precipitation temperature is generally around room temperature (such as 25° C. to 40° C.).

According to the catalyst preparation method of the present invention, the method further includes the operation of adjusting the pH value of the aqueous phase after mixing the reactants. Generally, the pH value of the aqueous phase is adjusted to 2-12, preferably 4-8, more preferably 4-7. The present invention has no special limitation on the reagents and methods for adjusting the pH value of the water phase, and it can be adjusted with commonly used alkaline aqueous solution, such as NaOH aqueous solution, KOH aqueous solution or ammonia aqueous solution to adjust the pH value of the system.

According to the catalyst preparation method of the present invention, after co-precipitation, it is preferable to keep the precipitate in water for a period of time, generally for 0.1h to 8h (preferably 0.5h to 5h); the temperature kept in water is generally 25°C to 70°C, Preferable is the temperature at the time of precipitation.

According to the catalyst preparation method of the present invention, the precipitate can be easily separated from the aqueous phase by filtration.

According to the catalyst preparation method of the present invention, the precipitate is preferably washed (generally with water), and heat-treated to obtain the catalyst of the present invention.

According to the catalyst preparation method of the present invention, the temperature of the heat treatment is generally 80°C to 600°C, preferably 200°C to 500°C, more preferably 250°C to 350°C. The heat treatment is preferably performed under the protection of an inert gas, such as under the protection of nitrogen or argon. The heat treatment time is generally 2h-5h, preferably 3h-5h.

The present invention also provides another method for preparing a tin catalyst, comprising: (1) a step of impregnating a carrier with an aqueous solution dissolved with tin salts, optional acids, and optional other metal salts; and (2) using silicic acid The step of treating the carrier obtained in (1) with salt.

According to the catalyst preparation method of the present invention, the carrier is preferably selected from one or more of activated carbon, alumina, molecular sieve and silica gel.

According to the catalyst preparation method of the present invention, if an acid is added, the preferred mode is to add the acid to the tin salt solution, and then impregnate the carrier with the tin salt solution; if other metal salts are added, the preferred mode is to add other metal salts The salt is first added to the tin brine solution, and then the tin brine solution is impregnated with the carrier; if acid and other metal salts are added at the same time, it is better to add the acid and other metal salts to the tin brine solution, and then use tin Saline solution impregnates the carrier.

According to the catalyst preparation method of the present invention, the silicate is generally one or more of sodium silicate and potassium silicate.

According to the catalyst preparation method of the present invention, the tin salt is generally stannous chloride (including anhydrous stannous chloride or stannous chloride dihydrate), tin tetrachloride (comprising anhydrous tin tetrachloride or pentahydrate One or more of tin tetrachloride) and stannous sulfate.

According to the catalyst preparation method of the present invention, the acid is preferably hydrochloric acid, sulfuric acid or nitric acid.

According to the catalyst preparation method of the present invention, there are no special restrictions on the type and amount of the other metal salts, as long as there is no obvious adverse effect on the catalyst performance or other benefits, an appropriate amount of other metal salts. The other metal salts are preferably selected from one or more of aluminum salts, titanium salts, zirconium salts, tin salts, zinc salts, magnesium salts, antimony salts and bismuth salts.

According to the catalyst preparation method of the present invention, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt can be 0.5-22, preferably 0.8-6, more preferably 1-5, further Preferably it is 1.5-5.

According to the catalyst preparation method of the present invention, the feeding ratio of all raw materials is such that the mass fraction of tin in the catalyst is 15%-45% (preferably 20%-35%).

According to the catalyst preparation method of the present invention, the consumption of silicate and tin salt is in the molar weight of silicon atom and tin atom respectively, the consumption of acid is in the molar weight that can release proton, the consumption of silicate, tin salt and acid Preferably, the following relational formula is satisfied: M _Si -M _Sn =2×M _protons .

According to the catalyst preparation method of the present invention, the temperature for treating the carrier obtained in (1) with silicate is generally around room temperature (such as 25° C. to 40° C.).

According to the catalyst preparation method of the present invention, the method also includes the operation of adjusting the pH value of the aqueous phase when treating the carrier obtained in (1) with silicate. Generally, the pH value of the aqueous phase is adjusted to 2-12, preferably 4-8, more preferably 4-7. The present invention has no special limitation on the reagents and methods for adjusting the pH value of the water phase, and it can be adjusted with commonly used alkaline aqueous solution, such as NaOH aqueous solution, KOH aqueous solution or ammonia aqueous solution to adjust the pH value of the system.

According to the preparation method of the catalyst of the present invention, after adding the silicate, it is preferably kept in water for a period of time, generally for 0.1h to 8h (preferably 0.5h to 5h); the temperature kept in water is generally 25°C to 70°C, Preferable is the temperature at the time of precipitation.

According to the catalyst preparation method of the present invention, the product can be easily separated from the water phase by filtration.

According to the preparation method of the catalyst of the present invention, the product is preferably obtained after washing (generally washing with water), filtering and heat treatment.

According to the catalyst preparation method of the present invention, the temperature of the heat treatment is generally 80°C to 600°C, preferably 100°C to 400°C, more preferably 200°C to 350°C. The heat treatment is preferably performed under the protection of an inert gas, such as under the protection of nitrogen or argon. The heat treatment time is generally 2h-5h, preferably 3h-5h.

The present invention also provides a catalyst obtained by any of the aforementioned methods.

Three, the application of catalyst of the present invention

The present invention also provides the application of any catalyst mentioned above in catalyzing the esterification reaction of alcohol and carboxylic acid or the transesterification reaction of alcohol and carboxylic acid ester.

Specifically, the present invention provides a method for producing carboxylate by the reaction of alcohol and carboxylic acid, characterized in that any of the aforementioned catalysts is used.

According to the present invention, the reaction temperature of esterification or transesterification is 160°C to 230°C, preferably 180°C to 210°C.

According to the present invention, after the reaction is finished, the catalyst is separated (for example, the catalyst is separated by filtration), and the catalyst is repeatedly used in the reaction.

Example part

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

In the context of this specification, all agents and starting materials are either commercially available or manufactured according to prior knowledge. In the following examples and comparative examples, unless otherwise specified, all reagents used are analytically pure.

In the context of this description, including in the following examples and comparative examples, the stannous oxide in the test and analysis, if no special instructions, then through the treatment of "under nitrogen protection, roasting at 200 ° C for 3 hours"; test And the tin oxide in the analysis, unless otherwise specified, was treated by "calcining at 500°C for 3 hours under the protection of nitrogen".

In the context of this specification, including in the following examples and comparative examples, X-ray photoelectron spectroscopy (XPS) adopts ESCALab220i-XL X-ray photoelectron spectroscopy produced by VG Scientific. (Test conditions: the excitation light source is monochromatic Al Kα X-rays, the power is 300W, the basic vacuum is 3×10 ^-9 mbar, and the electron binding energy is corrected by the C1s peak of elemental carbon.).

In the context of this specification, including in the following examples and comparative examples, the X-ray fluorescence spectroscopic analysis (XRF) adopts the 3271E X-ray fluorescence spectrometer produced by Rigaku Electric Industry Co., Ltd., and detects the spectrum with a scintillation counter and a proportional counter. Linear strength, quantitative and semi-quantitative analysis of element content by external standard method (test conditions: powder compression molding, rhodium palladium, excitation voltage 50kV, excitation current 50mA).

In the context of this description, including in the following examples and comparative examples, the atomic emission spectrometer (ICP-AES) adopts the U.S. Atom Scan 16 type inductively coupled plasma emission spectrometry (test condition: the catalyst is dissolved in HCl and HF In a solution with a volume ratio of 50:1, it was digested using a microwave digestion instrument produced by CEM in the United States.).

In the context of this specification, including in the following examples and comparative examples, the Raman spectrum was adopted by French JY company LAM-800 laser confocal Raman spectrometer (test conditions: incident light is 532nm, resolution is 4cm ^-1 , scanning The range is 100~1200cm ^-1 ).

In the context of this description, including in the following examples and comparative examples, the scanning electron microscope (SEM) adopts the Quanta 200F scanning electron microscope produced by FEI Company (test conditions: after the sample is dried, vacuum evaporation and gold spraying are used to increase Conductivity and contrast effect, the accelerating voltage of the analytical electron microscope is 20.0KV, and the magnification is 1-30k).

In the context of this description, including in the following examples and comparative examples, X-ray powder diffraction (XRD) adopts the D5005 type X-ray diffractometer (test condition: Cu target, Kα radiation, Ni filter plate produced by German Siemens) , tube voltage 35kV, tube current 45mA, scan range 2θ=5～70°).

In the following examples and comparative examples, the calculation method of the esterification rate is as follows:

The determination of the acid value in the calculation method of the above-mentioned esterification rate adopts the method specified in GB-1668-2008-T.

In the following examples and comparative examples, the esterification reaction selectivity adopts the American Agilent 7890A gas chromatograph, chromatographic conditions: capillary column (50m × 0.2mm × 0.5μm), FID detector, detection chamber temperature 280 ℃, column temperature The temperature is programmed from 60°C to 260°C, the temperature of the gasification chamber is 280°C, the flow rate of hydrogen is 30mL/min, the flow rate of air is 400mL/min, and the pressure of nitrogen is 10MPa.

The calculation method is as follows:

Preparation Example 1

Dissolve 2.26g of stannous chloride dihydrate (SnCl ₂ ·2H ₂ O) in 10ml of deionized water, and dissolve Na ₂ O·SiO ₂ ·9H ₂ O in deionized water. Add the two solutions into the flask at the same time at 30°C, feed the Si/Sn ratio to 1, add ammonia solution to adjust the pH value to 6, after the precipitation is complete, keep it at 50°C for 2 hours, filter, wash with water, °C, and then baked at 300 °C for 3 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, code A.

According to XRF analysis, the Si/Sn molar ratio of the catalyst is 0.96.

According to XPS analysis, the atomic mass fraction of tin on the surface of the catalyst is 5.12%; through ICP analysis, the mass fraction of tin in the catalyst is 63.5%.

Preparation Example 2

Dissolve 2.26g of stannous _chloride dihydrate ( _{SnCl 2} 2H ₂ O) in 40ml of water, add 4g of silica gel carrier to it, and soak for 5h; then slowly add 2.84g of Na ₂ O . Aqueous solution; stirred at 30°C for 3 hours, filtered, washed, dried at 80°C, and then calcined at 500°C for 3 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, code B.

According to ICP analysis, the mass fraction of tin in the catalyst is 19.6%.

Preparation Example 3

Dissolve 4.52g of stannous chloride dihydrate (SnCl ₂ ·2H ₂ O) in 50ml of deionized water, and dissolve 5.68g of Na ₂ O·SiO ₂ ·9H ₂ O in 50ml of deionized water. Add the two solutions into the flask at the same time at 30°C, add 5g of silica gel carrier to it, add ammonia solution to adjust the pH value to 7, stir and react at 30°C for 4 hours, filter, wash, and dry at 80°C , and then roasted at 300°C for 3 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, numbered C.

According to ICP analysis, the mass fraction of tin in the catalyst is 26.5%.

Preparation Example 4

Take 2.15g of stannous sulfate and dissolve it in 40ml of aqueous hydrochloric acid solution with a concentration of 1mol/L, and take K2O _{· SiO2} and dissolve it in deionized water. Add the two solutions into the flask at the same time at 30°C, feed the Si/Sn ratio to 3, add ammonia solution to adjust the pH value to 7, after the precipitation is complete, keep it at 30°C for 2 hours, filter, wash, and dry at 80°C ℃, and then baked at 250 ℃ for 4 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, code D.

According to XRF analysis, the Si/Sn molar ratio of the catalyst is 3.02.

According to ICP analysis, the mass fraction of tin in the catalyst is 37.3%.

Preparation Example 5

Dissolve 2.26g of stannous chloride dihydrate (SnCl ₂ ·2H ₂ O) in 80ml of aqueous hydrochloric acid solution with a concentration of 1mol/L, and dissolve K ₂ O·SiO ₂ in deionized water. Add the two solutions into the flask at the same time at 30°C, feed the Si/Sn ratio of 5, add ammonia solution to adjust the pH value to 7, after the precipitation is complete, keep it at 30°C for 4 hours, filter, wash, and dry at 80°C ℃, and then baked at 500 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, number E.

According to ICP analysis, the mass fraction of tin in the catalyst is 27.1%.

Preparation Example 6

Dissolve 3.51 g of tin tetrachloride pentahydrate (SnCl ₄ ·5H ₂ O) in 10 ml of deionized water, and dissolve Na ₂ O·SiO ₂ ·9H ₂ O in deionized water. Add the two solutions into the flask at the same time at 30°C, feed the Si/Sn ratio to 2, add ammonia solution to adjust the pH value to 7, after the precipitation is complete, keep it at 50°C for 0.5 hours, filter and wash, ℃, and then baked at 200 ℃ for 3 hours under the protection of nitrogen to obtain the tin catalyst of the present invention, number F.

According to ICP analysis, the mass fraction of tin in the catalyst is 44.0%.

Prepare comparative example 1

Get 5g tin protochloride dihydrate (SnCl ₂ 2H ₂ O) and be mixed with SnCl ₂ Mass fraction is the aqueous solution of 10%, adds 10g silica gel wherein, stirs 10h, then adds the ammonia solution that mass fraction is 20% wherein, Stir evenly, wash, filter, dry, and bake at 300°C for 3 hours under the protection of nitrogen to obtain the comparative tin catalyst, code G.

According to ICP analysis, the mass fraction of tin in the catalyst is 20.1%.

Prepare comparative example 2

The catalyst was prepared by the same method as that of Comparative Example 1, except that the amount of stannous chloride dihydrate (SnCl ₂ ·2H ₂ O) was 4 g. The catalyst number is H.

According to ICP analysis, the mass fraction of tin in the catalyst is 16.4%.

Prepare comparative example 3

The catalyst was prepared by the same method as that of Comparative Example 1, except that the amount of stannous chloride dihydrate (SnCl ₂ ·2H ₂ O) was 7 g. The catalyst number is I.

According to ICP analysis, the mass fraction of tin in the catalyst is 25.3%.

Prepare comparative example 4

The catalyst was prepared in the same manner as in Comparative Example 1, except that it was calcined at 500° C. for 3 hours under the protection of nitrogen. The catalyst number is J.

According to ICP analysis, the mass fraction of tin in the catalyst is 20.1%.

Reaction Example 1

In the reaction system, the molar ratio of benzoic acid to diethylene glycol is 2:1.15, n-butyl ether with 25% of the total mass of the reactants is added as a water carrier, and a catalyst with 1.5% of the total mass of the reactants is added. The temperature was raised to reflux, and the water was separated by reflux while reacting, and the reaction was stirred for 3 hours. After the reaction was finished, the stirring was stopped, and the mixture was allowed to stand for 10 minutes, the upper liquid phase was sampled and observed, and the liquid phase product and the catalyst were separated. The liquid phase product was sent for analysis, and the esterification rate and selectivity were calculated.

The reaction results are shown in Table 1.

Reaction Example 2

This example is used to compare and illustrate the repeated use effect of the tin catalyst of the present invention, the supported tin catalyst and stannous oxide.

Carry out according to the method for reaction example 1, difference is: except that first reaction uses catalyst A, G and stannous oxide, the catalyst of each reaction afterward reuses the catalyst that last reaction reclaims; Wherein, the series of catalyst A All tests were recovered by filtration. For the series of tests on catalyst G and tin oxide, due to the difficulty of filtration and the loss of catalyst, the catalyst was recovered by centrifugation.

The reaction results are shown in Table 2.

Table 1

catalyst Esterification rate/% selectivity/% upper liquid phase A 99.84 99.86 clear B 99.02 99.42 clear C 99.24 99.44 clear D. 99.53 99.74 clear E. 98.49 99.50 clear f 98.12 98.73 clear G 99.37 99.22 slightly turbid h 99.13 98.57 slightly turbid I 99.24 98.96 slightly turbid J 98.57 99.07 slightly turbid stannous oxide 99.20 99.48 turbid

Table 2

It can be seen from Figure 1 that the binding energy of tin in stannous oxide is at 486.31ev, and the binding energy of tin in tin dioxide is at 486.53ev. It can be seen from Fig. 2 that 487.89ev is the binding energy of tin in the supported catalyst with silica as the carrier, and 488.31 is the binding energy of tin in the catalyst of the present invention. As can be seen from Figures 1 and 2, the binding energy of tin in the catalyst of the present invention is the highest.

As can be seen from Fig. 3, near 110cm ^-1 and 211cm ^-1 , supported catalyst has two characteristic peaks consistent with stannous oxide, and catalyst of the present invention does not have these two characteristic peaks, on the contrary near 237cm ^-1 , this The inventive catalyst has a strong characteristic peak that neither the supported catalyst nor the stannous oxide has.

As can be seen from Figure 4, stannous oxide (untreated after purchase) is a single rectangular parallelepiped particle. It can be seen from Fig. 5 that the catalyst of the present invention has no clear outline, but is clustered together and is a substance with uniform appearance. It can be seen from Fig. 6 that in the supported catalyst, the support is clearly visible, and it is a substance with an uneven appearance.

It can be seen from Fig. 7, Fig. 8, Fig. 9 and Fig. 10 that the existing supported tin catalyst (calcined at 500°C for 3 hours under nitrogen protection) and stannous oxide have multiple sharp crystal features between 5° and 70° peak, while the catalyst of the present invention has no sharp crystal characteristic peak between 5° and 70°.

Claims (21)

1. a kind of preparation method of tin catalyst is characterized in that, comprises under the existence of carrier, carries out the step of co-precipitation to water-soluble tin salt and silicate; In described water, be dissolved with or undissolved acid ( preferably hydrochloric acid, sulfuric acid or nitric acid); the water may or may not be dissolved with other metal salts other than tin. 2. according to the described preparation method of claim 1, it is characterized in that, described carrier is selected from one or more in activated carbon, aluminum oxide, molecular sieve and silica gel. 3. The preparation method according to claim 1, characterized in that, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt is 0.8-6 (preferably 1.5-5). 4. according to the described preparation method of claim 1, it is characterized in that, the charging ratio of raw material makes in described catalyst, the mass fraction of tin is 15%～45%. 5. according to the described preparation method of claim 1, it is characterized in that, described other metal salts are selected from the one in aluminum salt, titanium salt, zirconium salt, tin salt, zinc salt, magnesium salt, antimony salt and bismuth salt or several. 6. according to the described preparation method of claim 1, it is characterized in that, described tin salt is selected from one or more in tin protochloride, tin tetrachloride and stannous sulfate. 7. according to the described preparation method of claim 1, it is characterized in that, described silicate is selected from one or more in sodium silicate and potassium silicate. 8. The preparation method according to claim 1, characterized in that it comprises the operation of adjusting the pH value of the aqueous phase to 2-12 (preferably adjusting the pH value of the aqueous phase to 4-8). 9. The preparation method according to claim 1, characterized in that it includes the step of heat treatment at 80°C-600°C (preferably 200°C-500°C) under the protection of an inert gas. 10. A method for preparing a tin catalyst, comprising: (1) a step of impregnating a support with an aqueous solution of tin salts, optional acids and other metal salts; and (2) silicic acid The step of treating the carrier obtained in (1) with salt. 11. The preparation method according to claim 10, characterized in that, based on the molar weight of silicon atoms and tin atoms, the feed ratio of the silicate to tin salt is 0.8-6 (preferably 1.5-5). 12. The preparation method according to claim 10, characterized in that the feed ratio of the raw materials is such that the mass fraction of tin in the catalyst is 15% to 45%. 13. The preparation method according to claim 10, characterized in that it includes the step of heat treatment at 80°C-600°C (preferably 200°C-500°C) under the protection of inert gas. 14. A tin catalyst, characterized in that it is obtained by the preparation method according to any one of claims 1-13. 15. An inorganic tin catalyst, characterized in that the catalyst contains Sn-O-Si bonds; and under the protection of nitrogen, after the catalyst is calcined at 500°C for 3 hours, there are no tin oxide crystals and suboxide in its XRD spectrum. Characteristic peaks of tin crystals. 16. A tin catalyst, characterized in that the catalyst contains Sn ^- O-Si bonds; and under the protection of nitrogen, after the catalyst is calcined at 300°C for 3 hours, in its Raman spectrum, there is a There are no characteristic peaks around 110cm ^-1 and 211cm ^-1 or there are characteristic peaks with relatively small intensity. 17. The catalyst according to claim 15 or 16, characterized in that, in the catalyst, the valence state of tin is divalent or tetravalent. 18. Catalyst according to claim 15 or 16, characterized in that the catalyst is an amorphous solid. 19. Use of the catalyst according to any one of claims 14 to 16 in catalyzing the esterification reaction of alcohol and carboxylic acid or the transesterification reaction of alcohol and carboxylic acid ester. 20. A method for producing carboxylate by the reaction of alcohol and carboxylic acid, characterized in that the catalyst according to any one of claims 14 to 16 is used. 21. The method according to claim 20, characterized in that it comprises the step of separating the catalyst after the reaction is finished, and reusing the catalyst for said reaction.