Ti / zr-si porous catalyst, method for preparing the same, and method for catalyzing esterification

Abstract

The application belongs to the technical field of organic ester, and particularly relates to a Ti / Zr-Si porous catalyst, a preparation method thereof and a catalytic esterification method. The application introduces an organic acid source in a system for preparing a molecular sieve, and a core-shell type heterogeneous esterification catalyst material with titanium / zirconium in a tetra-coordination framework as a core and titanium / zirconium in a penta / six-coordination as a shell is prepared by combining the porous molecular sieve with a binder precursor. The catalyst contains abundant secondary pores in the molecular sieve crystals and between the binders, which effectively improves the esterification reaction performance and activity stability of the catalyst.

Description

Technical Field

[0001] This invention belongs to the technical field of organic esters, specifically relating to a porous catalyst for esterification reactions and its preparation method. Background Technology

[0002] Organic esters, including ethyl acetate, methyl oleate, and triglyceride acetate, are important chemical raw materials, and their efficient synthesis is of great significance. Typically, organic acids react with alcohols via dehydration under the action of an acid catalyst to form esters. However, esterification is a reversible reaction. To improve the ester yield, azeotropic distillation or the use of dehydrating agents to remove water is often employed to promote the shift of the reaction equilibrium. Furthermore, an excess of acid or alcohol can be added to the reaction system to shift the reaction towards esterification.

[0003] The catalysts commonly used in esterification reactions are mainly homogeneous catalysts such as sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, and organometallic compounds. Although homogeneous catalysts can catalyze esterification reactions under relatively mild conditions, their reaction times are long and their production efficiency is low. To address these issues, heterogeneous esterification catalysts have attracted widespread attention. Heterogeneous esterification catalysts refer to catalytic systems where liquid and solid phases coexist in the esterification reaction. Such systems can provide higher reaction efficiency and product purity, and have the advantages of easy separation and recovery. Nevertheless, the activity and stability of heterogeneous esterification catalysts remain important factors restricting their industrialization. When using heterogeneous esterification catalysts, deactivation is mainly caused by corrosion of the catalyst by organic acids and dehydration of alcohols under acidic conditions. Therefore, heterogeneous esterification catalysts need to be acid-resistant and have low activity for alcohol dehydration reactions.

[0004] Heteroatomic molecular sieves, such as titanium-silicon molecular sieves and zirconium-silicon molecular sieves, possess unique Lewis acidity. They exhibit excellent activity not only in selective oxidation reactions but also possess certain transesterification properties. Furthermore, both titanium-silicon and zirconium-silicon molecular sieves exhibit excellent hydrothermal stability and acid resistance. However, perhaps due to limitations in sieve pore size or the weak acidity of the sieves, there are very few research reports on the direct use of heteroatomic molecular sieves for catalyzing acid-base esterification to synthesize organic esters. Patent applications 202210760318.4 and 202210762756.4 disclose that under reaction temperatures of 80–300℃, reaction times of 2–24 h, catalyst dosages of 0.1–2%, and atmospheric pressure, heteroatomic molecular sieves such as titanium-silicon, iron-silicon, or tin-silicon molecular sieves can catalyze the reaction of C3–C20 straight-chain or branched fatty acids with pentaerythritol to form esters. To enhance the catalytic activity of heteroatom molecular sieves in esterification reactions, acid centers such as ionic liquids and phosphotungstic acid can be supported. However, in this case, the molecular sieve primarily functions as a support. Furthermore, sulfonate catalysts supported on amorphous SiO2-TiO2 also exhibit good activity in esterification reactions, but amorphous SiO2-TiO2 is again primarily used as a support. Although heteroatom molecular sieves possess certain esterification properties, their pore size is typically below 1 nm. Therefore, during the catalytic esterification process, their intracrystalline active centers have difficulty interacting with organic acids and alcohols with larger molecular sizes, and their catalytic performance still needs further improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a Ti / Zr-Si porous catalyst, which can effectively improve the catalytic performance of existing molecular sieve catalysts in the catalytic esterification process.

[0006] The first objective of this invention is to provide a method for preparing a Ti / Zr-Si porous catalyst, comprising the following steps:

[0007] (1) Silicon source A, titanium source, zirconium source, structure directing agent and water are mixed and hydrolyzed and dispersed under normal pressure to obtain precursor gel I. Organic acid source is added to precursor gel I to obtain precursor gel II.

[0008] (2) The precursor gel II was transferred to the reactor and hydrothermally reacted under autogenous pressure. After cooling, depressurization, filtration and drying were performed to obtain Ti / Zr-Si porous molecular sieve.

[0009] (3) Mix silicon source B, titanium source, zirconium source, alkali source and water, and hydrolyze and disperse them under normal pressure to obtain binder precursor;

[0010] (4) The Ti / Zr-Si porous molecular sieve, binder precursor and guar powder are mixed, and finally kneaded, shaped, dried and calcined to obtain porous esterification catalyst material.

[0011] Normally, molecular sieve synthesis is carried out under alkaline conditions. However, this invention introduces an organic acid source into the molecular sieve preparation system, which can neutralize the precursor gel I to form a precursor gel II containing organic carboxylic acid groups. These organic carboxylic acid groups can regulate the nucleation and crystal growth of the molecular sieve to a certain extent, thereby affecting the integrity, morphology, and coordination state of the Ti / Zr framework of the molecular sieve. When the hydrophobic groups of the organic carboxylic acid groups interact to form clusters that are internally hydrophobic and externally hydrophilic, these clusters can also interact with the molecular sieve precursor or its crystallization transition state, thereby introducing secondary pores and surface hydroxyl groups into the molecular sieve crystals, improving the diffusion performance within the molecular sieve crystals, increasing the accessibility of the active centers within the molecular sieve crystals, and regulating the Lewis acidity generated by the surface hydroxyl groups. Therefore, the Ti / Zr-Si porous molecular sieve prepared in step (2) can achieve good esterification catalytic activity and better activity stability. Based on this, the present invention adds steps (3) and (4) to combine the Ti / Zr-Si porous molecular sieve with excellent esterification activity and activity stability with the binder precursor. On the one hand, this can improve the structural strength of the catalyst, reduce the loss of porous molecular sieve during the catalytic esterification reaction, and further improve the stability of the catalyst. On the other hand, it can construct Lewis acid centers with different coordination states from the framework Ti / Zr in the molecular sieve, and construct a core-shell active center network with four-coordinate framework Ti / Zr as the core and five / six-coordinate non-framework Ti / Zr as the shell, further improving the esterification reaction activity of the catalyst.

[0012] Preferably, silicon source A is selected from at least one of organosilicates, silica gel, silica fume, and silica sol; in order to reduce the influence of heteroatoms in the silicon source on the crystallization products of the catalyst, a single silicon source is preferred; more preferably, organosilicates, such as at least one of methyl orthosilicate, isopropyl orthosilicate, ethyl orthosilicate, tetraethoxysilane, and tetraethyl orthosilicate.

[0013] Preferably, the silicon source B is selected from at least one of organosilicate, silica gel, silica fume, silica sol, and Ti / Zr-Si porous molecular sieve synthesis mother liquor; to improve the strength of the catalyst, at least one of organosilicate, silica sol, and Ti / Zr-Si porous molecular sieve synthesis mother liquor is preferred; more preferably, at least one of silica sol and Ti / Zr-Si porous molecular sieve synthesis mother liquor is preferred. The Ti / Zr-Si porous molecular sieve synthesis mother liquor is recovered from the filtrate after filtration in step (2).

[0014] Preferably, in steps (1) and (3), the titanium source is selected from at least one of organic titanium esters and / or inorganic titanium salts such as titanium tetrachloride, tetrabutyl titanate, tetraethyl titanate, and titanium tetrafluoride; preferably, the titanium source is at least one of tetrabutyl titanate and tetraethyl titanate.

[0015] Preferably, the zirconium source in steps (1) and (3) is selected from at least one of organozirconium compounds such as zirconium acetate, zirconium isooctanoate, zirconium n-propoxide, zirconium naphthenate, zirconium tetra-tert-butoxide, zirconium acetylacetonate, and tetrabutyl zirconate; preferably, the zirconium source is at least one of tetrabutyl zirconate and zirconium acetylacetonate.

[0016] Preferably, the structure directing agent in step (1) is selected from at least one of aliphatic amines, aliphatic alcohol amines, quaternary ammonium bases and quaternary ammonium salts.

[0017] Specifically, the general structural formula of the quaternary ammonium base is:

[0018]

[0019] Wherein, R1, R2, R3, and R4 are at least one of C1-C4 alkyl groups, wherein the C1-C4 alkyl groups are selected from at least one of C1-C4 straight-chain alkyl groups and C3-C4 branched-chain alkyl groups. R1, R2, R3, and R4 can be independently methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl.

[0020] Specifically, the general structural formula of the quaternary ammonium salt is:

[0021]

[0022] Wherein, R1, R2, R3, and R4 are at least one of C1-C4 alkyl groups, wherein the C1-C4 alkyl groups are selected from at least one of C1-C4 straight-chain alkyl groups and C3-C4 branched-chain alkyl groups. R1, R2, R3, and R4 can independently be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl; X in the quaternary ammonium salt is at least one of halide ions such as F, Cl, Br, and I.

[0023] The aliphatic amine has the general structural formula R5(NH2)n, where n is an integer of 1 or 2. When n is 1, R5 is at least one of C1-C6 alkyl groups, selected from at least one of C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl, or n-hexyl. When n is 2, R5 is at least one of C1-C6 alkylene groups, selected from at least one of C1-C6 straight-chain alkylene groups and C3-C6 branched alkylene groups, such as methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene.

[0024] The aliphatic alcoholamine has the general structural formula R6(ONH)n, where n is an integer of 1 or 2. When n is 1, R6 is at least one of C1-C6 alkyl groups, selected from at least one of C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl, or n-hexyl. When n is 2, R6 is at least one of C1-C6 alkylene groups, selected from at least one of C1-C6 straight-chain alkylene groups and C3-C6 branched alkylene groups, such as methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene.

[0025] Preferably, the structure-directing agent is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tripropylamine, triethylamine, diethylamine, tributylamine, and hexamethylenediamine. More preferably, it is selected from at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and hexamethylenediamine. Specifically, when the structure-directing agent is tetraethylammonium hydroxide, triethylamine, or diethylamine, a molecular sieve with a BEA topology is prepared; when the structure-directing agent is tetrapropylammonium hydroxide or tripropylamine, a molecular sieve with an MFI topology is prepared; when the structure-directing agent is hexamethylenediamine, a ZSM-48 molecular sieve is prepared; and when the structure-directing agent is tetrabutylammonium hydroxide or tributylamine, a molecular sieve with a MEI topology is prepared.

[0026] Preferably, the organic acid source includes at least one of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids.

[0027] Specifically, the monocarboxylic acid is a monocarboxylic acid containing C2-C18 groups, wherein the C2-C18 groups can be straight-chain alkyl, isoalkyl, alkenyl, polycyclic cycloyl, and aromatic groups. The monocarboxylic acid can be at least one selected from acetic acid, acrylic acid, methacrylic acid, n-butyric acid, n-hexanoic acid, isooctanoic acid, isononanoic acid, p-isopropylcyclohexylcarboxylic acid, benzoic acid, lauric acid, and oleic acid; preferably, the monocarboxylic organic acid is at least one selected from isooctanoic acid, lauric acid, and oleic acid.

[0028] Specifically, the dicarboxylic acid is at least one selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, terephthalic acid, phthalic acid, glutamic acid, and aspartic acid. Preferably, the dicarboxylic acid is at least one selected from adipic acid, terephthalic acid, and glutamic acid.

[0029] Specifically, the tricarboxylic acid is at least one of citric acid, pyromellitic acid, etc.

[0030] Preferably, in step (1), the molar ratio of silicon source A, titanium source, zirconium source, structure directing agent, organic acid source, and water is 1:(0.0001~0.023):(0.0001~0.021):(0.05~0.39):(0.05~3):(15~200), and silicon source A, titanium source, and zirconium source are calculated as SiO2, TiO2, and ZrO2, respectively.

[0031] As a preferred option, the conditions for hydrolysis by heating in step (1) are: temperature 40-80℃ and time 0.5-24h.

[0032] In this invention, the temperature and time of the hydrothermal reaction in step (2) are among the important factors affecting the crystal form, grain size, and morphology of the hydrothermal product. Specifically, the conditions for the hydrothermal reaction in step (2) are: temperature 70–190°C, time 1–72 h. As a further preferred option, the conditions for the hydrothermal reaction in step (2) are: first react at 100–130°C for 6–25 h, and then raise the temperature to 160–180°C for 18–48 h.

[0033] The pressure of the hydrothermal reaction system is another important factor affecting the crystal form and crystallization rate of the product, and the self-generated pressure of the reaction system depends on the size of the empty volume in the reactor. In order to improve the efficiency of the hydrothermal reaction, preferably, the total volume of the precursor gel II added in step (2) is 60-85% of the reactor capacity.

[0034] As a preferred option, the drying conditions in step (2) are: temperature 110-170℃, time 6-48h.

[0035] Preferably, the molar ratio of silicon source B, titanium source, zirconium source, alkali source and water in step (3) is 1:(0.05~0.3):(0.05~0.3):(0.1~3):(5~100); more preferably, the molar ratio of silicon source B, titanium source, zirconium source, alkali source and water in step (3) is 1:(0.08~0.15):(0.07~0.15):(0.2~2):(15~50).

[0036] Preferably, the alkali source in step (3) is selected from at least one of organic and inorganic alkalis such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; more preferably, at least one of tetramethylammonium hydroxide and sodium hydroxide.

[0037] Preferably, the conditions for hydrolysis dispersion in step (3) are a temperature of 40–80°C and a time of 1–16 h.

[0038] Preferably, in step (4), the weight ratio of the Ti / Zr-Si porous molecular sieve, the oxide in the binder precursor, and the guar gum powder is 1:(0.1~0.4):(0.01~0.1).

[0039] Preferably, the drying conditions in step (4) are a temperature of 80–120°C and a time of 4–24 hours.

[0040] Preferably, the calcination conditions in step (4) are a temperature of 400–600°C and a time of 2–10 h.

[0041] A second objective of this invention is to provide a Ti / Zr-Si porous catalyst, which is prepared by any of the above-described preparation methods.

[0042] Preferably, the Ti / Zr-Si porous catalyst comprises a molecular sieve intracrystalline secondary pore structure and a binder mesoporous structure.

[0043] As a further preferred option, the size of the secondary pore structure within the molecular sieve crystal in the catalysis is 1–7 nm, and the volume is 0.10–0.26 cm³. 3 / g; the overall pore size of the catalyst is 1–16.9 nm, and the volume is 0.18–0.41 cm³. 3 / g.

[0044] Preferably, the Lewis acid content of the Ti / Zr-Si porous catalyst is 26.1–335.8 μmol / g; more preferably, the Lewis acid content is 39.2–217.9 μmol / g.

[0045] The third objective of this invention is to propose the application of any of the above-mentioned Ti / Zr-Si porous catalysts in catalytic esterification reactions.

[0046] Preferably, the catalytic esterification reaction refers to using a Ti / Zr-Si porous catalyst as the catalyst, at a temperature of 160–350 °C, a pressure of 0.13–6 MPa, and a mass hourly space velocity (WHSV) of 0.05–50 h⁻¹ for the organic acid. -1 Under certain conditions, organic acids and alcohols are introduced into a fixed-bed reactor at a molar ratio of carboxyl to hydroxyl groups of 1:(0.1-10) to obtain organic esters.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] This invention improves the diffusion performance within the molecular sieve crystals and enhances the accessibility of active centers by introducing an organic acid source into the molecular sieve preparation system. It also modulates the Lewis acidity generated by the framework Ti / Zr and surface hydroxyl groups, thereby improving the esterification catalytic activity and stability of the Ti / Zr-Si porous molecular sieve. Furthermore, by combining the porous molecular sieve with an amorphous Ti / Zr-Si binder precursor, the structural strength of the catalyst can be improved, reducing catalyst loss during the esterification process and further enhancing catalyst stability. Simultaneously, Lewis acid centers with different coordination states to the Ti / Zr in the molecular sieve can be constructed, creating a core-shell active center network with a four-coordinate framework Ti / Zr core and five / six-coordinate non-framework Ti / Zr shell, further enhancing the esterification activity of the catalyst. Detailed Implementation

[0049] The present invention will be further described below with reference to the specification and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0050] The unified preparation method for the Ti / Zr-Si porous catalyst in the examples is as follows:

[0051] (1) Mix silicon source A, titanium source, zirconium source, structure directing agent and water, and hydrolyze and disperse them under normal pressure to obtain precursor gel I. Add organic acid source to precursor gel I to obtain precursor gel II.

[0052] (2) The precursor gel II was transferred to the reactor and hydrothermally reacted under autogenous pressure. After cooling, depressurization, filtration and drying were performed to obtain Ti / Zr-Si porous molecular sieve.

[0053] (3) Mix silicon source B, titanium source, zirconium source, alkali source and water, and hydrolyze and disperse them under normal pressure to obtain binder precursor;

[0054] (4) The Ti / Zr-Si porous molecular sieve, binder precursor and guar powder are mixed, and finally kneaded, shaped, dried at 110℃ for 10h and calcined at 550℃ for 4h to obtain porous esterification catalyst material.

[0055] The unified method for preparing organic esters using Ti / Zr-Si porous catalysts in the examples is as follows:

[0056] The prepared Ti / Zr-Si porous catalyst was pressed into tablets and sieved to obtain catalyst particles of 20-40 mesh. 2g of these particles were weighed and loaded into the catalyst bed of a fixed-bed reactor. Under a nitrogen atmosphere, the temperature was raised and maintained at a constant pressure. Then, a mixture of organic acid and alcohol was introduced according to the ratio of carboxyl to hydroxyl groups. The resulting reactants were condensed and subjected to water-oil separation. The aqueous phase was discharged, and the oil phase was fractionated to obtain the product, an organic ester.

[0057] Examples 1-3

[0058] The raw materials, raw material ratios, and preparation conditions for the preparation of Ti / Zr-Si porous catalysts in Examples 1-3 are detailed in Table 1 below.

[0059] Table 1

[0060]

[0061]

[0062]

[0063] Examples 4-6

[0064] The raw materials, raw material ratios, and preparation conditions for the preparation of Ti / Zr-Si porous catalysts in Examples 4-6 are detailed in Table 2 below.

[0065] Table 2

[0066]

[0067]

[0068] Examples 7-9

[0069] The raw materials, raw material ratios, and preparation conditions for the preparation of Ti / Zr-Si porous catalysts in Examples 7-9 are detailed in Table 3 below.

[0070] Table 3

[0071]

[0072]

[0073] Comparative Example 1

[0074] The difference between Comparative Example 1 and Example 1 is that no organic acid source was added in step (1). The rest is the same as Example 1, and will not be described in detail here.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 1 is that steps (3) and (4) are omitted. The rest is the same as Example 1, and will not be described in detail here.

[0077] Comparative Example 3

[0078] The difference between Comparative Example 3 and Example 1 is that the binder does not contain Ti and Zr, while the rest is the same as Example 1, and will not be described in detail here.

[0079] Performance Test 1

[0080] The Ti / Zr-Si porous catalysts prepared in Examples 1-9 and Comparative Examples 1-3 were subjected to the following performance tests, and the catalyst structures and catalytic performance are shown in the table below. The determination methods were as follows: acid content was analyzed by a BIQ-RAD FTS3000 Fourier transform infrared spectrometer; pore size and pore volume were measured and calculated using a Micrometrics ASAP 2460 physical adsorption analyzer.

[0081]

[0082]

[0083] Table 4

[0084]

[0085]

[0086] Performance Test 2

[0087] The porous molecular sieves of Ti / Zr-Si porous catalysts after esterification reaction in Examples 1 and 1-3 were recovered and cyclically catalyzed under the same esterification reaction conditions. The conversion rate and selectivity of organic alcohols were measured and the results are shown in the table below.

[0088] Table 5

[0089]

Claims

1. A method for preparing a Ti / Zr-Si porous catalyst, characterized in that, Includes the following steps: (1) Silicon source A, titanium source, zirconium source, structure directing agent and water are mixed and hydrolyzed and dispersed under normal pressure to obtain precursor gel I. Organic acid source is added to precursor gel I to obtain precursor gel II. (2) The precursor gel II was transferred to the reactor and hydrothermally reacted under autogenous pressure. After cooling, depressurization, filtration and drying, Ti / Zr-Si porous molecular sieve was obtained. (3) Mix silicon source B, titanium source, zirconium source, alkali source and water, and hydrolyze and disperse them under normal pressure to obtain binder precursor; (4) The Ti / Zr-Si porous molecular sieve, binder precursor and guar powder are mixed, and finally kneaded, shaped, dried and calcined to obtain Ti / Zr-Si porous catalyst.

2. The method for preparing the Ti / Zr-Si porous catalyst according to claim 1, characterized in that, Organic acid sources include at least one of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids.

3. The method for preparing the Ti / Zr-Si porous catalyst according to claim 1, characterized in that, In step (1), the molar ratio of silicon source A, titanium source, zirconium source, structure directing agent, organic acid source and water is 1: (0.0001~0.023): (0.0001~0.021): (0.05~0.39): (0.05~3): (15~200).

4. The method for preparing the Ti / Zr-Si porous catalyst according to claim 1, characterized in that, In step (3), the molar ratio of silicon source B, titanium source, zirconium source, alkali source and water is 1:(0.05~0.3):(0.05~0.3):(0.1~3):(5~100).

5. The method for preparing the Ti / Zr-Si porous catalyst according to claim 1, characterized in that, In step (4), the weight ratio of Ti / Zr-Si porous molecular sieve, oxide in binder precursor and guar gum powder is 1:(0.1~0.4):(0.01~0.1).

6. A Ti / Zr-Si porous catalyst, characterized in that, It is prepared using the method described in any one of claims 1-5.

7. The Ti / Zr-Si porous catalyst according to claim 6, characterized in that, The secondary pore size within the molecular sieve of the Ti / Zr-Si porous catalyst is 1~7 nm, and the volume of the secondary pores within the molecular sieve is 0.10~0.26 cm³. 3 / g; the secondary pore size of the catalyst is 1~16.9 nm, and the secondary pore volume is 0.18~0.41 cm³. 3 / g.

8. A Ti / Zr-Si porous catalyst according to claim 6, characterized in that, The Lewis acidity of the Ti / Zr-Si porous catalyst is 26.1~335.8 μmol / g.

9. The application of the Ti / Zr-Si porous catalyst according to any one of claims 6-8 in catalytic esterification reaction.

10. The application according to claim 9, characterized in that, The catalytic esterification reaction refers to the reaction using a Ti / Zr-Si porous catalyst as the catalyst, at a temperature of 160~350℃, a pressure of 0.13~6MPa, and a mass hourly space velocity (WHSV) of 0.05~50h for the organic acid. -1 Under certain conditions, organic acids and alcohols are introduced into a fixed-bed reactor at a molar ratio of carboxyl to hydroxyl groups of 1:(0.1~10) to obtain organic esters.

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