A defective zirconium sulfate solid acid catalyst, its preparation method and application

Abstract

This invention relates to the fields of catalytic materials and organic synthesis technology, and specifically discloses a zirconium oxide sulfate solid acid catalyst with surface oxygen vacancy defects, its preparation method, and its applications. The preparation method includes heat-treating a zirconium oxide precursor in a reducing atmosphere to introduce oxygen vacancy defects onto the zirconium oxide surface; subsequently, introducing a sulfur-containing substance through impregnation; and obtaining the sulfated zirconium oxide solid acid catalyst after drying and calcination. The catalyst can be used to catalyze the acidolysis reaction of trichloromethylbenzene compounds with aromatic carboxylic acids to prepare aromatic acyl chlorides, and is particularly suitable for the preparation of benzoyl chloride, isophthaloyl chloride, and terephthaloyl chloride. This catalyst has advantages such as high activity, good stability, and a simple preparation method.

Description

Technical Field

[0001] This invention relates to the fields of catalytic materials and organic synthesis technology, and in particular to a method for preparing a zirconium sulfate solid acid catalyst with surface oxygen vacancy defects, and the application of the catalyst in the acidolysis reaction of trichloromethylbenzene compounds with aromatic carboxylic acids to prepare the corresponding aromatic acyl chlorides. Background Technology

[0002] Benzoyl chloride, isophthaloyl chloride, and terephthaloyl chloride are commonly used acylation reagents and important intermediates in organic synthesis, widely applied in pharmaceuticals, pesticides, dyes, and polymer materials. Among them, isophthaloyl chloride and terephthaloyl chloride are also crucial monomers in the preparation of high-performance polymers such as aramid fibers, and their product quality significantly impacts the performance of downstream materials. Currently, the industrial preparation of aromatic acyl chlorides typically employs a process route involving the reaction of aromatic carboxylic acids with chlorinating reagents such as phosgene, thionyl chloride, and phosphorus trichloride. While these methods can achieve the preparation of the corresponding acyl chlorides, they still have certain limitations. For example, phosgene is highly toxic, requiring stringent safety management and equipment conditions during transportation, storage, and use; the thionyl chloride and phosphorus trichloride methods easily generate acidic waste gases and related byproducts during the reaction, leading to problems such as equipment corrosion and heavy post-treatment burdens. Therefore, developing relatively safer and less environmentally burdensome methods for preparing aromatic acyl chlorides is a practical need.

[0003] To address the aforementioned issues, a technical route for preparing aromatic acyl chlorides using trichloromethylbenzene compounds as raw materials has attracted attention. This method involves the acidolysis of trichloromethylbenzene, bis(trichloromethyl)benzene compounds, and their corresponding carboxylic acids to produce benzoyl chloride, isophthaloyl chloride, or terephthaloyl chloride. Compared to the traditional route that uses external chlorinating agents for acyl chloride production, this method reduces the direct use of highly toxic chlorinating agents to some extent, thus showing promising application prospects. This reaction typically employs homogeneous catalysts, such as ferric chloride reported in patent CN104230704A, and zinc chloride and aluminum chloride homogeneous catalysts reported in patent CN 104387263A. These homogeneous catalysts dissolve in the product acyl chloride and require distillation for separation. During distillation, these homogeneous catalysts readily catalyze the polymerization of the product acyl chloride to form tar, significantly affecting the product yield.

[0004] Based on the mechanism of acyl chloride reaction, this invention presents a heterogeneous zirconium oxide sulfate catalyst with high activity and stability. Zirconia sulfate is a common solid acid catalyst, attracting attention in various acid-catalyzed reactions due to its strong acidity. Existing zirconium oxide sulfate catalysts typically obtain acidic sites by introducing sulfur-containing species onto the surface of a zirconium oxide support, which can meet the requirements of acid-catalyzed reactions to a certain extent. However, in liquid-phase acidolysis systems, the weak interaction between sulfur and zirconium oxide leads to problems such as low activity, high coking selectivity, and poor stability when traditional zirconium oxide sulfate catalysts are used in these systems. This invention addresses these problems by modulating the interaction between sulfur and the zirconium oxide support, significantly improving the reactivity and stability of zirconium oxide sulfate, and possessing significant industrial application value. Summary of the Invention

[0005] Purpose of the invention One object of the present invention is to provide a zirconium sulfate catalyst that modulates the catalyst activity and stability by constructing oxygen vacancies on the surface of a zirconium oxide support before loading sulfur, for use in the acyl chloride reaction of trichloromethylbenzenes and aromatic carboxylic acids to prepare aromatic acyl chlorides.

[0006] Another objective of this invention is to provide a heterogeneous solid acid catalyst that facilitates the separation of the catalyst and reactants, thereby avoiding acid-catalyzed coking and polymerization reactions during subsequent distillation. Technical solution

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a zirconium sulfate solid acid catalyst with surface oxygen vacancy defects, comprising the following steps: (1) Zirconia precursors were heat-treated in a reducing atmosphere to prepare zirconia rich in oxygen vacancy defects; (2) Based on this, sulfur is introduced into the zirconium oxide carrier by impregnation. (3) After drying and calcination, zirconium sulfate catalyst is obtained.

[0008] This invention utilizes the calcination of zirconium hydroxide, a precursor of zirconium oxide, under reducing conditions in a reducing atmosphere to construct abundant oxygen vacancy defects on the zirconium oxide surface. This allows for the introduction of sulfur into these defect sites during subsequent sulfur induction, enhancing the interaction between sulfur and zirconium oxide and modulating the activity of Lewis acid centers. By varying the type of reducing atmosphere, temperature, and processing time, this method can construct zirconium oxide supports with different oxygen vacancy defects. Further sulfur introduction allows for the regulation of the structure of Lewis acid active centers, thereby enhancing their catalytic activity and stability in acylation reactions.

[0009] The preferred technical solution of this invention is as follows: The precursor of zirconium oxide is zirconium hydroxide, which is prepared by a deposition precipitation method. The precursor of zirconium hydroxide can be any one of zirconium nitrate or zirconium oxychloride.

[0010] In step (1), the reducing atmosphere is at least one of CO or H2, and the volume fraction of the reducing gas in the reducing atmosphere is 10% to 100%, preferably 20% to 100%, with the remainder being inert gases; the heat treatment temperature is 300 to 900°C, preferably 350 to 800°C; and the treatment time is 1 to 20 hours, preferably 5 to 12 hours.

[0011] In step (2), the sulfur precursor is at least one of sulfuric acid, hydrosulfuric acid or ammonium sulfate, with a loading of 0.1-10%, preferably 0.5-5%.

[0012] In step (3), the calcination temperature after loading sulfur in step (2) is 300-900℃, preferably 400-800℃, and the time is 3-8h.

[0013] Secondly, the present invention provides the application of the above-mentioned zirconium sulfate solid acid catalyst in the preparation of aromatic acyl chlorides.

[0014] Furthermore, the application involves catalyzing the acidolysis reaction of trichloromethylbenzene compounds with aromatic carboxylic acids to prepare the corresponding aromatic acyl chlorides.

[0015] Furthermore, the aromatic acyl chloride includes benzoyl chloride, isophthaloyl chloride, or terephthaloyl chloride.

[0016] Furthermore, the application includes the following reaction pathway: When trichloromethylbenzene and benzoic acid are used as raw materials, an acid hydrolysis reaction is carried out in the presence of the catalyst to produce benzoyl chloride; When 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene is used as a raw material, it undergoes acid hydrolysis reaction with the corresponding aromatic dicarboxylic acid to generate the corresponding aromatic diacyl chloride; wherein the molar ratio of aromatic carboxylic acid to trichloromethylbenzene compound is 1.0~1.2:1.

[0017] The aromatic dicarboxylic acid is isophthalic acid or terephthalic acid; the aromatic diacyl chloride is isophthaloyl chloride or terephthaloyl chloride.

[0018] The reaction temperature is 60-120℃; preferably, the temperature is 60-120℃; the amount of catalyst is 0.05-5% of the reactants, more preferably, 0.1-3%; preferably, the reaction time is 1-5h, more preferably, 2-4h. Beneficial effects

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: Introducing oxygen vacancy defects on the zirconium oxide surface through heat treatment in a reducing atmosphere is beneficial for increasing the number of active sites on the catalyst, thereby enhancing catalytic activity. After defect modulation, the binding stability of sulfur-containing species on the support surface is improved, which helps reduce the loss of active components during the reaction process, thus improving catalyst stability. The catalyst can be used for the acidolysis reaction of trichloromethylbenzene compounds with aromatic carboxylic acids, and can be used for the preparation of benzoyl chloride and phthaloyl chloride compounds, demonstrating significant application value. The method described in this invention has relatively simple process steps and is suitable for scale-up applications. Detailed Implementation

[0020] This embodiment provides a defective zirconium oxide catalyst, Cat-CO-450-H2SO4, modified by reduction under CO atmosphere and treated with sulfuric acid, and its preparation and application. First, the precursor is prepared: an appropriate amount of zirconium oxychloride (ZrOCl2·8H2O) is dissolved in deionized water to prepare a solution. Under stirring, 25% (w / w) ammonia is slowly added dropwise to adjust the pH to 9-10. After aging and filtration, the filter cake is washed with deionized water until no chloride ion precipitate is detected by silver nitrate. Subsequently, it is dried at 110℃ for 12 hours, ground, and sieved to obtain zirconium hydroxide precursor powder. Then, reduction treatment is performed: 5.0 g of the above precursor is placed in the constant temperature zone of a tube furnace. High-purity nitrogen is first purged for 30 minutes, then the atmosphere is switched to 100% (v / w) CO atmosphere, and the temperature is increased to 450℃ at a rate of 10℃ / min and held for 2 hours. After treatment, it is cooled to room temperature under nitrogen protection. Subsequently, sulfur-containing treatment and calcination were carried out: the reduced carrier was immersed in a 2.0 mol / L sulfuric acid aqueous solution with a liquid-to-solid ratio to ensure complete immersion of the carrier, and immersed for 4 hours; after filtration, it was dried at 110℃ for 12 hours; and then calcined at 550℃ in air for 3 hours to obtain the catalyst Cat-CO-450-H2SO4.

[0021] The application evaluation is as follows: In a four-necked flask equipped with a reflux condenser and thermometer, 10 mmol of trichloromethylbenzene, 10 mmol of benzoic acid, toluene solvent, and 0.10 g of the catalyst were added. The mixture was heated to 150 °C and stirred for 4 h. Gas chromatography analysis showed that the conversion rate of trichloromethylbenzene was 99%, and the selectivity of benzoyl chloride was 98%. Using the same catalyst, the acidolysis reaction of 1,3-bis(trichloromethyl)benzene with isophthalic acid was carried out at 140 °C for 6 h, achieving a conversion rate of 98% and a selectivity of isophthalic chloride of 97%. Using the same catalyst, the acidolysis reaction of 1,4-bis(trichloromethyl)benzene with terephthalic acid achieved a conversion rate of 97% and a selectivity of terephthalic chloride of 96%.

[0022] Example 2 This example provides a defective zirconium oxide catalyst, Cat-COH2400-NH4SO4, modified by reduction in a CO / H2 mixed atmosphere and treated with ammonium sulfate, and its preparation and application. The zirconium hydroxide precursor was prepared according to the method in Example 1. The precursor was placed in a tube furnace, and a mixed gas with a volume fraction of 50% CO and 50% H2 was introduced. The temperature was increased to 400°C at a heating rate of 5°C / min and held for 1.5 h. After cooling, it was immersed in a 2.0 mol / L ammonium sulfate aqueous solution for 4 h. After drying, it was calcined at 550°C for 3 h in air to obtain the catalyst Cat-CO / H2-400-NH4SO4. The reaction conditions described in Example 1 were evaluated as follows: in the acid hydrolysis of trichloromethylbenzene, the conversion rate was 98% and the selectivity of benzoyl chloride was 97%; in the acid hydrolysis of 1,3-bis(trichloromethyl)benzene, the conversion rate was 97% and the selectivity of isophthaloyl chloride was 96%; in the acid hydrolysis of 1,4-bis(trichloromethyl)benzene, the conversion rate was 96% and the selectivity of terephthaloyl chloride was 95%.

[0023] Example 3 This example provides a defective zirconium oxide catalyst, Cat-H2-500-H2S, modified by reduction under H2 atmosphere and treated with hydrosulfuric acid, and its preparation and application. A dried zirconium hydroxide precursor was placed in a tube furnace, and a 100% (v / v) H2 atmosphere was introduced. The temperature was raised to 500°C and held for 3 hours. After cooling, the support was immersed in a 2.0 mol / L zinc hydrosulfate aqueous solution for 6 hours. After solid-liquid separation and drying, the catalyst was calcined at 550°C for 3 hours in air to obtain the catalyst Cat-H2-500-H2S. Under the action of this catalyst, the acid hydrolysis reaction of trichloromethylbenzene achieved a conversion rate of 98% and a benzoyl chloride selectivity of 97%. When used in the acid hydrolysis reaction of 1,3-bis(trichloromethyl)benzene, the conversion rate was 97% and the isophthaloyl chloride selectivity was 96%. When used in the acid hydrolysis reaction of 1,4-bis(trichloromethyl)benzene, the conversion rate was 96% and the terephthaloyl chloride selectivity was 95%.

[0024] Example 4: The zirconium hydroxide precursor was placed in a mixed atmosphere of 50% H2 and 50% N2 (by volume), heated to 350°C and held for 2 hours; then impregnated with a 2.0 mol / L copper sulfate solution for 6 hours; after drying, it was calcined at 550°C for 3 hours to obtain the catalyst Cat-H. 2mix -350-H2SO4. Under the action of this catalyst, the conversion rate of the acid hydrolysis reaction of trichloromethylbenzene is 97%, and the selectivity of benzoyl chloride is 96%; the conversion rate of the acid hydrolysis reaction of 1,3-bis(trichloromethyl)benzene is 96%, and the selectivity of isophthaloyl chloride is 95%; the conversion rate of the acid hydrolysis reaction of 1,4-bis(trichloromethyl)benzene is 95%, and the selectivity of terephthaloyl chloride is 94%.

[0025] Example 5: The support was placed in a 50% CO / 50% H2 mixed atmosphere, heated to 550℃ and held for 1 hour. After cooling, the support was placed in a rotating container and impregnated with an equal volume of 3.0 mol / L sulfuric acid until it reached a slightly wet state, and then allowed to stand for 2 hours. After drying, it was calcined at 550℃ in air for 3 hours to obtain the catalyst Cat-CO / H2-550-H2SO4. When used in the acid hydrolysis of trichloromethylbenzene, this catalyst achieved a conversion rate of 98% and a benzoyl chloride selectivity of 97%; in the acid hydrolysis of 1,3-bis(trichloromethyl)benzene, it achieved a conversion rate of 97% and an isophthaloyl chloride selectivity of 96%; and in the acid hydrolysis of 1,4-bis(trichloromethyl)benzene, it achieved a conversion rate of 96% and a terephthaloyl chloride selectivity of 95%.

[0026] Comparative Example 1: This comparative example provides a conventional zirconium hydroxide catalyst, Cat-0, without reduction pretreatment. The same zirconium hydroxide precursor as in Example 1 was directly impregnated in a 2.0 mol / L sulfuric acid solution for 4 hours without reduction treatment; after filtration and drying, it was calcined at 550°C for 3 hours in air to obtain the comparative catalyst, Cat-0. Evaluation was conducted under the same conditions as in Example 1: the conversion rate of the trichloromethylbenzene acid hydrolysis reaction was 85%, and the selectivity for benzoyl chloride was 90%; the conversion rate of the 1,3-bis(trichloromethyl)benzene acid hydrolysis reaction was 88%, and the selectivity for isophthaloyl chloride was 87%; the conversion rate of the 1,4-bis(trichloromethyl)benzene acid hydrolysis reaction was 87%, and the selectivity for terephthaloyl chloride was 86%. To more intuitively compare the catalytic effects of each example with the comparative example, the main experimental data are summarized in the table below. It can be seen that after pretreatment with a reducing atmosphere (CO, H2, or a mixture thereof) to construct oxygen vacancy defects, the catalyst exhibits significantly better conversion rates and selectivity than traditional catalysts in the acidolysis / acylation reactions of trichlorotoluene and xylene derivatives.

[0027] Table 1. Effects of catalyst performance on the conversion and selectivity of trichlorotoluene

[0028] Table 2. Effects of catalyst performance on the conversion / selectivity of m-xylene acid hydrolysis

[0029] Table 3. Effects of catalyst performance on the conversion / selectivity of p-xylene acid hydrolysis

Claims

1. A method for preparing a solid zirconium sulfate catalyst with surface oxygen vacancy defects, characterized in that: (1) The zirconia precursor was heat-treated in a reducing atmosphere to prepare zirconia rich in oxygen vacancy defects; (2) Based on this, sulfur was introduced into the zirconia support by impregnation; (3) Zirconia sulfate catalyst was obtained after drying and calcination.

2. The preparation method according to claim 1, characterized in that: The reducing atmosphere is at least one of CO or H2, wherein the volume fraction of the reducing gas in the reducing atmosphere is 10% to 100%, preferably 20% to 100%, and the remainder is an inert gas; the heat treatment temperature is 300 to 900°C, preferably 350 to 800°C; and the treatment time is 1 to 20 hours, preferably 5 to 12 hours.

3. The preparation method according to claim 1, characterized in that: The sulfur precursor is at least one of sulfuric acid, hydrosulfuric acid, or ammonium sulfate, with a loading of 0.1-10%, preferably 0.5-5%.

4. The zirconium oxide sulfate solid acid catalyst prepared by any one of claims 1 to 3, characterized in that, The roasting temperature is 300-900℃, preferably 400-800℃, and the time is 3-8h.

5. A method for preparing an aromatic acyl chloride, comprising: Aromatic acyl chlorides are prepared by reacting trichloromethylbenzene compounds with aromatic carboxylic acids at 40-150°C under the action of zirconium sulfate as described in any one of 1-4; preferably, the molar ratio of aromatic carboxylic acids to trichloromethylbenzene compounds is 1.0-1.2:

1.

6. The method according to claim 5, characterized in that, The trichloromethylbenzene compounds are trichlorotoluene, 1,3-bis(trichloromethyl)benzene, and 1,4-bis(trichloromethyl)benzene; the aromatic carboxylic acids are benzoic acid, isophthalic acid, and terephthalic acid.

7. The method according to claims 5-6, characterized in that... The aromatic acyl chlorides produced by the reaction of trichloromethylbenzene compounds with their aromatic carboxylic acids are benzoyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

8. The method according to claims 5-7, characterized in that, The reaction temperature is 60-160℃; preferably, the temperature is 60-140℃; the amount of catalyst is 0.05-5% of the reactants, more preferably, 0.1-3%; preferably, the reaction time is 1-5h, more preferably, 2-4h.

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