A catalyst for preparing chlorobenzene and a preparation method and application thereof

Abstract

The application provides a catalyst preparation method for preparing chlorinated benzene. Diatomite is used as a matrix, and the surface of the matrix is covered with CuS phase and Fe2S3 phase from inside to outside. The catalyst prepared by the method has a benzene conversion rate of more than 91% and a chlorinated benzene yield of more than 80%, and the catalyst has good performance.

Description

Technical Field

[0001] This invention relates to a benzene monochloride catalyst, its preparation method, and its application. Background Technology

[0002] my country began producing chlorobenzene in the 1950s, but for many years the supply could not meet the demand, necessitating the import of a considerable amount of nitrochlorobenzene to satisfy domestic market needs. Due to the urgent market demand, a construction boom swept across the country in the early 1990s, with various regions building or expanding chlorobenzene plants. Chlorobenzene is an important chemical raw material and organic intermediate, and it is also a crucial basic organic intermediate for balancing chlorine, alkali, and hydrogen in chlor-alkali plants. Domestically, it is mainly used for the synthesis of nitrochlorobenzene.

[0003] Currently, my country's chlorobenzene production scale, technology level, and quality indicators have all reached the international advanced level. Its production capacity accounts for about 75% of the global total capacity. Therefore, it not only meets the domestic market demand, but also exports a certain amount in recent years, especially the large-scale export of its downstream derivatives, such as nitrochlorobenzene and its downstream products such as p-aminophenol, paracetamol, o-phenylenediamine, o-methyl ether, and vanillin.

[0004] There are currently 12 domestic manufacturers producing chlorobenzene with a capacity of 10,000 tons per year, of which 6 have a capacity of over 50,000 tons per year.

[0005] Since 2005, my country's chlorobenzene production capacity has reached 440,000 tons / year, of which about 80% of the product is used to synthesize nitrochlorobenzene, and the remainder is used in organic synthesis industries such as dichlorobenzene and pesticides.

[0006] Domestic production of chlorobenzene can already meet market demand, but domestic companies continue to expand production, leading to market saturation. Although some companies are producing downstream products, bringing the chlorobenzene market back to a new supply-demand balance, there is already a surplus in the domestic nitrochlorobenzene market.

[0007] In recent years, with the rapid development of my country's p- and o-nitrochlorobenzene industry, chlorobenzene production capacity has increased rapidly. The formulation and implementation of the EU REACH draft will directly impact the production of chlorobenzene-related products in the EU region, leading to a relative increase in external demand and presenting export opportunities for my country. Chlorobenzene is mainly used to synthesize p- and o-nitrochlorobenzene, 2,4-dinitrochlorobenzene, and diphenyl ethers, with a small amount used in pesticide synthesis and as a solvent.

[0008] Currently, manufacturers primarily employ a direct chlorination method, where benzene and chlorine are continuously chlorinated under Fe catalysis to obtain a chlorinated liquid. This liquid is then washed with water, neutralized, and subjected to crude and fine distillation to remove excess benzene and polychlorinated benzene, yielding the final chlorobenzene product. The hydrogen chloride released during the reaction is absorbed with water to produce hydrochloric acid; polychlorinated benzene is recovered as ortho- and para-dichlorobenzene. This method is characterized by a short production process and mature technology, and is widely used by manufacturers both domestically and internationally for chlorobenzene production. However, the current process suffers from drawbacks such as high iron content in wastewater, large wastewater volume, low benzene reaction yield, and high energy consumption. Summary of the Invention

[0009] The purpose of this invention is to develop a novel catalyst for use in the production of chlorobenzene, overcoming the shortcomings of current production processes, such as large wastewater volume, high iron content, low benzene reaction yield, high energy consumption, and numerous impurities.

[0010] The main technical solution of the present invention is a catalyst for preparing chlorobenzene, characterized in that the catalyst uses diatomaceous earth as a matrix, and the surface of the matrix is ​​covered with CuS phase and Fe2S3 phase from the inside to the outside, respectively. The catalyst is used to prepare monochlorobenzene by benzene chlorination.

[0011] This invention provides a method for preparing the catalyst, comprising the following steps:

[0012] 1) Prepare an aqueous solution of diatomaceous earth, add sodium sulfide solution under stirring to form a suspension, and control the reaction temperature at 50-70℃;

[0013] 2) Prepare a salt solution of ferric nitrate, ferric sulfate, or ferric chloride by mixing it with a salt solution of copper nitrate, copper sulfate, or copper chloride;

[0014] 3) Add the mixed solution from step 2) to the suspension from step 1) under stirring conditions;

[0015] 4) Aging at 50-80℃ for 30-60 minutes;

[0016] 5) Filter the precipitate from step 4), wash it with water, dry it, add water and pore-forming agent to granulate it, make it into tablets, and finally calcine it in stages.

[0017] Generally, the pore-forming agent is selected from stearic acid, calcium stearate or magnesium stearate.

[0018] The stirring speed under the specified stirring conditions is 500-700 r / min.

[0019] The stepwise calcination conditions are as follows: first, raise the temperature from room temperature to 100-120℃ and hold for 2-4 hours; then, raise the temperature to 200-250℃ and hold for 8-20 hours; finally, raise the temperature to 300-400℃ and hold for 2-4 hours.

[0020] The present invention also provides that the catalyst can be used in the reaction of benzene chlorination to produce monochlorobenzene: the catalyst can be packed in layers in a reaction vessel, benzene is injected into the upper part of the catalyst layer in the reaction vessel, chlorine gas is introduced into the lower part of the catalyst layer, and the reaction liquid is taken out from the lower part of the reaction vessel.

[0021] The chlorination reaction temperature is controlled between 30-80℃.

[0022] Generally, the post-treatment of the chlorination reaction solution is as follows: the chlorination reaction solution is washed with water, washed with alkali, and then distilled in a distillation column to obtain chlorinated benzene product.

[0023] The present invention provides a method for preparing benzene monochloro, achieving a benzene monochloro yield of over 80% and a benzene conversion rate of over 90%. This achieves the effects of energy saving and improved conversion rate. Detailed Implementation

[0024] The present invention will be further illustrated by the following embodiments, but is not limited to these embodiments.

[0025] Example 1

[0026] Weigh 500g of diatomaceous earth and prepare a 2.0L solution, place it in a reaction vessel, take 224.4g of sodium sulfide and prepare a 1.0L solution, add the sodium sulfide solution to the diatomaceous earth solution at a reaction temperature of 60℃ and a stirring speed of 500r / min to obtain a suspension.

[0027] 400g of ferric nitrate was weighed and prepared into a 2.0L solution. 100g of copper nitrate was weighed and prepared into a 500mL solution. At a reaction temperature of 60℃ and a stirring speed of 500r / min, the ferric nitrate solution and copper nitrate solution were added dropwise to the diatomaceous earth suspension. After the addition was completed, the temperature was raised to 65℃ and aged for 40min. The mixture was filtered, washed, dried, and granulated with water and stearic acid. The granules were then formed into rings and finally calcined in steps. The calcination conditions were as follows: under an air atmosphere, the temperature was raised to 110℃ and held for 4h, then raised to 240℃ and held for 20h, and finally raised to 400℃ and held for 4h to obtain catalyst C1.

[0028] Example 2

[0029] Weigh 500g of diatomaceous earth and prepare a 2.0L solution, place it in a reaction vessel, take 173.1g of sodium sulfide and prepare a 1.0L solution, add the sodium sulfide solution to the diatomaceous earth solution at a reaction temperature of 60℃ and a stirring speed of 500r / min to obtain a suspension.

[0030] 400g of copper nitrate was weighed and prepared into a 2.0L solution. 100g of ferric nitrate was weighed and prepared into a 500mL solution. At a reaction temperature of 60℃ and a stirring speed of 500r / min, the ferric nitrate solution and copper nitrate solution were added dropwise to the diatomaceous earth suspension. After the addition was completed, the temperature was raised to 65℃ and aged for 40min. The mixture was filtered, washed, dried, and granulated with water and stearic acid. The granules were then formed into rings and finally calcined in steps. The calcination conditions were as follows: under an air atmosphere, the temperature was raised to 100℃ and held for 3h, then raised to 200℃ and held for 15h, and finally raised to 350℃ and held for 4h to obtain catalyst C2.

[0031] Example 3

[0032] Weigh 500g of diatomaceous earth and prepare a 2.0L solution, place it in a reaction vessel, take 264.1g of sodium sulfide and prepare a 1.0L solution, add the sodium sulfide solution to the diatomaceous earth solution at a reaction temperature of 60℃ and a stirring speed of 500r / min to obtain a suspension.

[0033] 400g of copper sulfate was weighed and prepared into a 2.0L solution, and 100g of ferric sulfate was weighed and prepared into a 500mL solution. At a reaction temperature of 60℃ and a stirring speed of 500r / min, the ferric sulfate solution and copper sulfate solution were added dropwise to the diatomaceous earth suspension. After the addition was completed, the temperature was raised to 75℃ and aged for 50min. The mixture was filtered, washed, dried, and granulated with water and stearic acid. The granules were then formed into rings and finally calcined in steps. The calcination conditions were as follows: under an air atmosphere, the temperature was raised to 100℃ and held for 3h, then raised to 200℃ and held for 15h, and finally raised to 350℃ and held for 4h to obtain catalyst C3.

[0034] Example 4

[0035] Weigh 500g of diatomaceous earth and prepare a 2.0L solution, place it in a reaction vessel, take 285.4g of sodium sulfide and prepare a 1.0L solution, add the sodium sulfide solution to the diatomaceous earth solution at a reaction temperature of 60℃ and a stirring speed of 500r / min to obtain a suspension.

[0036] 400g of ferric sulfate was weighed and prepared into a 2.0L solution, and 100g of copper sulfate was weighed and prepared into a 500mL solution. At a reaction temperature of 60℃ and a stirring speed of 600r / min, the ferric sulfate solution and copper sulfate solution were added dropwise to the diatomaceous earth suspension. After the addition was completed, the temperature was raised to 55℃ and aged for 60min. The mixture was filtered, washed, dried, and then granulated with water and stearic acid. The granules were then formed into rings and finally calcined in steps. The calcination conditions were as follows: under an air atmosphere, the temperature was raised to 120℃ and held for 2h, then raised to 220℃ and held for 15h, and finally raised to 380℃ and held for 4h to obtain catalyst C4.

[0037] Example 5

[0038] Weigh 500g of diatomaceous earth and prepare a 2.0L solution, place it in a reaction vessel, take 267.4g of sodium sulfide and prepare a 1.0L solution, add the sodium sulfide solution to the diatomaceous earth solution at a reaction temperature of 60℃ and a stirring speed of 500r / min to obtain a suspension.

[0039] 300g of ferric chloride was weighed and prepared into a 2.0L solution. 100g of copper sulfate was weighed and prepared into a 500mL solution. At a reaction temperature of 55℃ and a stirring speed of 550r / min, the ferric chloride solution and copper sulfate solution were added dropwise to the diatomaceous earth suspension. After the addition was completed, the temperature was raised to 55℃ and aged for 60min. The mixture was filtered, washed, dried, and granulated with water and stearic acid. The granules were then formed into rings and finally calcined in steps. The calcination conditions were as follows: under an air atmosphere, the temperature was raised to 120℃ and held for 2h, then raised to 220℃ and held for 15h, and finally raised to 380℃ and held for 4h to obtain catalyst C5.

[0040] Example 6

[0041] The catalyst was applied to the reaction of benzene chlorination to produce chlorobenzene.

[0042] Take 100 ml of catalyst and fill it into a fixed-bed reactor in layers. There are a total of 3 layers of catalyst and 4 layers of magnetic rings. The top and bottom layers are filled with magnetic rings. The mixture of catalyst and magnetic rings is filled from top to bottom in the following order: magnetic ring: catalyst 1: magnetic ring: catalyst 2: magnetic ring: catalyst 3: magnetic ring, catalyst 1: catalyst 2: catalyst 3 = 1:1:1. The reaction conditions are: reaction temperature 30-80℃, benzene feed rate 100 g / h, chlorine flow rate 12 L / h. The results are shown in Table 1.

[0043] Table 1 Activity evaluation results

[0044] Serial Number Benzene conversion rate / % Chlorinated benzene yield / % C1 91.7 80.1 C2 92.3 82.1 C3 92.2 83.2 C4 91.6 82.8 C5 91.7 82.0

[0045] As can be seen from the data in Table 1, when the catalyst designed by the technical solution of this invention is applied to the reaction of benzene chlorination to chlorobenzene, the conversion rate of benzene reaches more than 91% and the yield of chlorobenzene reaches more than 80%, indicating that the catalyst has good performance.

Claims

1. The application of a catalyst, characterized in that, The catalyst is used in the reaction of benzene chlorination to produce monochlorobenzene: the catalyst is packed in layers in a reaction vessel, benzene is injected into the upper part of the catalyst layer, chlorine gas is introduced into the lower part of the catalyst layer, and the reaction liquid is collected from the lower part of the reaction vessel; the catalyst is based on diatomaceous earth, and the surface of the matrix is ​​covered with CuS phase and Fe2S3 phase from the inside to the outside. The method for preparing the catalyst includes the following steps: 1) Prepare an aqueous solution of diatomaceous earth, add sodium sulfide solution under stirring to form a suspension, and control the reaction temperature at 50-70℃; 2) Prepare a salt solution of ferric nitrate, ferric sulfate, or ferric chloride by mixing it with a salt solution of copper nitrate, copper sulfate, or copper chloride; 3) Add the mixed solution from step 2) to the suspension from step 1) under stirring conditions; 4) Aging at 50-80℃ for 30-60 minutes; 5) Filter the precipitate from step 4), wash it with water, dry it, add water and pore-forming agent to granulate it, make it into tablets, and finally calcine it in stages.

2. The application of the catalyst as described in claim 1, characterized in that, The pore-forming agent is selected from stearic acid, calcium stearate or magnesium stearate.

3. The application of the catalyst as described in claim 1, characterized in that, The stirring speed under the specified stirring conditions is 500-700 r / min.

4. The application of the catalyst as described in claim 1, characterized in that, The stepwise calcination conditions are as follows: first, raise the temperature from room temperature to 100-120℃ and hold for 2-4 hours; then, raise the temperature to 200-250℃ and hold for 8-20 hours; finally, raise the temperature to 300-400℃ and hold for 2-4 hours.

5. The application of the catalyst as described in claim 1, characterized in that, The chlorination reaction temperature is controlled between 30-80℃.

6. The application of the catalyst as described in claim 1, characterized in that, Post-treatment of chlorination reaction solution: The chlorination reaction solution is washed with water, washed with alkali, and then distilled in a distillation column to obtain chlorobenzene product.