Manganese oxide-supported cobalt-chromium catalyst, method for producing the same, and use in the synthesis of parachlorobenzaldehyde

Abstract

In highly selective oxidation of parachlorotoluene to parachlorobenzaldehyde, catalytic activity and selectivity were insufficient, the environmental impact was high, and there were issues with catalyst reusability. [Solution] The present invention provides a manganese oxide-supported cobalt chromium catalyst, a method for producing the same, and a method for producing parachlorobenzaldehyde by oxidizing parachlorotoluene using the same. This catalyst is prepared by dissolving a certain amount of manganese salt and metal salt precursors of cobalt and chromium, measured based on the support ratio, in deionized water and stirring to obtain a mixed solution. Acid is added to the resulting solution, and the mixture is heated and stirred. The resulting solid is then filtered, washed, and calcined. The resulting catalyst is used in the selective oxidation of parachlorotoluene, achieving high conversion and selectivity. The catalyst of the present invention is inexpensive to produce, environmentally friendly, and easy to recover and reuse. Furthermore, it exhibits excellent reaction activity and product selectivity despite relatively mild reaction conditions, making it suitable for industrial use.

Description

[Technical Field] 【0001】 The present invention relates to the field of organic catalyst technology, and more specifically to a manganese oxide-supported cobalt-chromium catalyst, a method for producing the same, and a method for producing parachlorobenzaldehyde by highly selective oxidation of parachlorotoluene using the catalyst. [Background technology] 【0002】 Parachlorobenzaldehyde is a fine organic chemical intermediate widely used in fields such as pharmaceuticals, dye intermediates, and agrochemicals. It is used in the synthesis of pharmaceuticals such as fennarol and aminophen amino acids, as well as plant growth regulators such as uniconazole and polyoxysol. 【0003】 Conventional chlorination hydrolysis methods use chlorine gas and soluble metal salts for the reaction, but this method has drawbacks such as being demanding on equipment conditions and polluting the environment with wastewater. With the development of green chemistry, environmentally friendly oxidizing agents such as hydrogen peroxide (H2O2) and oxygen (O2) are attracting attention in the field of fine chemicals. 【0004】 While hydrogen peroxide is important for reducing waste emissions and achieving green chemistry, its storage and transportation pose risks, making it unsuitable for industrial use. On the other hand, oxygen is inexpensive, readily available, safe, and convenient, so there is much research being conducted on directly oxidizing parachlorotoluene to produce parachlorobenzaldehyde as an oxidizing agent. 【0005】 However, this process demands high performance from the catalyst, so the development of highly active and highly selective catalysts has become the focus of research. 【0006】 Regarding this reaction pathway, Minmin Tsai et al. ("Production of parachlorobenzaldehyde from parachlorotoluene by air oxidation," Chemical World, 2002) investigated the oxidation reaction in an air and oxygen atmosphere and reported that the yield when using oxygen was 28%, which is superior to air oxidation, but the reaction activity is still low. 【0007】 Toyasu et al. (Catalysis Communications 8, 2007, pp.1279~1283) produced parachlorobenzaldehyde by oxygen oxidation of parachlorotoluene under atmospheric pressure and low temperature conditions using acetic acid-water as a solvent and cobalt and manganese salts as catalysts, obtaining a conversion rate of 33.7% and a selectivity of 66.6%. While this method has the advantages of being simple and low cost, it has the disadvantages of difficulty in separating and recovering the homogeneous catalyst system and low selectivity for the target product. 【0008】 Patent document CN101138729A reports that a conversion rate of 43.7% was achieved by supporting the active metal components cobalt and manganese on Al2O3 and performing liquid-phase oxidation, while adjusting the oxygen flow rate, temperature, and catalyst composition ratio. However, further improvement in catalytic activity is still desired. 【0009】 The method for producing parachlorobenzaldehyde by liquid-phase oxygen oxidation of parachlorotoluene has the advantages of simple and mild operating conditions, low pollution, and easy separation and reuse of raw materials and solvents. Although the aforementioned studies have attempted to improve this reaction through different approaches, challenges remain to be addressed. 【0010】 Specifically, there are problems such as low utilization efficiency of the oxidizing agent, insufficient catalyst activity, and the easy generation of by-products such as parachlorobenzyl alcohol, parachlorobenzoic acid, and 4-chlorobenzyl acetate, resulting in low selectivity. Furthermore, homogeneous catalysts using manganese salts produce a large amount of wastewater, making catalyst reuse difficult. 【0011】 Therefore, developing heterogeneous catalysts suitable for this reaction and further improving reaction activity and selectivity of the target product remains an important research challenge. [Prior art documents] [Patent Documents] 【0012】 [Patent Document 1] China Patent Publication No. CN101138729A [Non-patent literature] 【0013】 [Non-Patent Document 1] Production of parachlorobenzaldehyde from parachlorotoluene by air oxidation, Chemical World, 2002. [Non-Patent Document 2] Catalysis Communications 8, 2007, pp.1279-1283 [Overview of the project] [Problems that the invention aims to solve] 【0014】 This invention addresses the challenges of low catalytic activity and low selectivity in existing technologies for the production of parachlorobenzaldehyde, and provides a supported cobalt-chromium catalyst and a method for producing the same for highly selective oxidation of parachlorotoluene to produce parachlorobenzaldehyde. 【0015】 In this invention, by adjusting the active components and their ratios in the catalyst and optimizing the reaction system conditions, highly selective production becomes possible. Furthermore, the catalyst's manufacturing process is simple, and it can be easily reused after separation, washing, drying, and high-temperature calcination, making it suitable for industrial production. [Means for solving the problem] 【0016】 The technical means of the present invention are as follows: A method for producing a catalyst in which cobalt and chromium are supported on manganese oxide. After dissolving a manganese salt and precursor metal salts of cobalt and chromium in deionized water to obtain a mixed solution, an acid is added, and the reaction is allowed to proceed by heating and stirring. After the reaction is completed, filtration, drying, and calcination are performed to obtain the target cobalt-chromium supported catalyst. 【0017】 Specifically, it includes the following steps. (1) Weigh a certain amount of manganese salt, and further weigh the precursor metal salts of cobalt and chromium so as to have a predetermined supported amount. Dissolve them in deionized water to prepare a mixed solution. 【0018】 (2) After sufficiently dissolving the above substances at a certain temperature, add a certain amount of acid and continue heating and stirring. 【0019】 (3) After the reaction is completed, the solid mixture is suction filtered, washed, dried, and calcined to obtain the target catalyst, which is a dark brown powder. 【0020】 In step (1), the manganese salt is selected from one or more of permanganate, chloride, acetate, acetylacetonate salt, and nitrate, preferably including two or more of permanganate (Na or K), manganese acetate, and manganese nitrate. 【0021】 Also, the metal salts of cobalt and chromium are also selected from one or more of chloride, acetate, acetylacetonate salt, and nitrate, and acetate and nitrate are particularly preferred. 【0022】 The precursor of the cobalt salt is selected from cobalt chloride, cobalt acetate, cobalt acetylacetonate, and cobalt nitrate, and cobalt acetate and cobalt nitrate are particularly preferred. 【0023】 Similarly, the precursor of the chromium salt is selected from chromium chloride, chromium acetate, chromium acetylacetonate, and chromium nitrate, and chromium acetate and chromium nitrate are particularly preferred. 【0024】 As a specific example, manganese salts are mixtures of high manganese salts (K or Na) and manganese acetate, with a molar ratio of 1:1 to 2, more preferably 1:1 to 1:5. 【0025】 In step (1), Co and Cr Carrying The quantity is relative to the mass of Mn in the carrier. each A concentration of 2-15 wt% is preferred, and based on the amount of Mn contained in high potassium manganate, Carrying The amount is 4-10%, more preferably 4-8%, and even more preferably 5-7%. 【0026】 The mass ratio of Co to Cr is 1:3 to 3:1, more preferably 1:2 to 2:1, and even more preferably 1:1. 【0027】 The concentration of Co salt in the mixed solution is 3.5 to 18.5 g / L, more preferably 4 to 15 g / L, and even more preferably 4 to 10 g / L. The concentration of the Cr salt is 5.5 to 35.5 g / L, more preferably 8 to 30 g / L, and even more preferably 10 to 20 g / L. 【0028】 The stirring time in step (2) is 12 to 48 hours, more preferably 16 to 32 hours, and the heating temperature is 70 to 120°C, more preferably 90 to 110°C. 【0029】 The acid is selected from at least one of hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid, with hydrochloric acid or nitric acid being particularly preferred. 【0030】 For example, when 7.08 g of potassium manganate is used, the amount of acid added is 2 to 8 mL, preferably 3 to 5 mL, and the mass-to-volume ratio is 0.25 to 1.13 mL / g, more preferably 0.4 to 0.75 mL / g. 【0031】 In step (3), the drying temperature is 70 to 120°C, more preferably 80 to 100°C, and the drying time is 4 to 15 hours, more preferably 8 to 10 hours. The firing temperature is 300-700°C, more preferably 400-500°C, and the firing time is 3-6 hours, more preferably 4-5 hours. 【0032】 The present invention also provides a supported cobalt-chromium catalyst obtained by the above manufacturing method. This catalyst is a multi-metal oxide in which cobalt and chromium are supported in predetermined amounts on a manganese oxide support. 【0033】 Preferably, the amount of cobalt and chromium supported in the catalyst is 2 to 15 wt%, each. 【0034】 Furthermore, the present invention also relates to the use of the manganese oxide-supported cobalt-chromium catalyst to selectively oxidize parachlorotoluene to produce parachlorobenzaldehyde. 【0035】 The overall concept of the present invention is to provide a method for obtaining parachlorobenzaldehyde by mixing the catalyst, solvent, bromine-based initiator, and parachlorotoluene, and carrying out an oxidation reaction at 60 to 110°C (preferably 80 to 110°C, more preferably 90 to 110°C) while introducing a certain amount of oxygen. 【0036】 The solvent is at least one of acetic acid, acetonitrile, acetic anhydride, and water, preferably a mixture of acetic acid and water, specifically acetic acid. The volume ratio of water is 3 to 8:1, preferably 4 to 6:1, and parachlorotoluene. The volume ratio of the solvent is 1:3 to 14, preferably 1:5 to 14, and more preferably 1:8 to 14. 【0037】 The brominated initiator is preferably one of KBr, HBr, or NaBr, and the volume ratio is 20 to 100 μL, more preferably 35 to 70 μL, and even more preferably 40 to 60 μL of the brominated initiator per 1 mL of parachlorotoluene. 【0038】 The volume ratio in the reaction mixture is preferably parachlorotoluene:solvent:bromine initiator = 1:(2~14):(0.01~0.1), and the oxygen flow rate is 20~100 mL / min, more preferably 50~100 mL / min, and even more preferably 60~100 mL / min. 【0039】 The mass ratio of parachlorotoluene to the highly selective catalyst is 1:(0.01~0.1), preferably 1:(0.03~0.1), and more preferably 1:(0.04~0.1). 【0040】 The oxidation reaction time is 4 to 24 hours, more preferably 10 to 24 hours, and even more preferably 6 to 12 hours. [Effects of the Invention] 【0041】 The present invention has the following beneficial effects compared to the prior art. 1. The present invention provides a supported cobalt-chromium catalyst, which has a simple manufacturing method, readily available and low-cost raw materials, and is also easy to separate and recover. 2. By introducing cobalt and manganese into the cerium oxide-based catalyst, the specific surface area of ​​the catalyst is increased, thereby enhancing the catalytic activity of the catalyst in the oxidative denitrification reaction. 3. The method for producing parachlorobenzaldehyde by oxidation of parachlorotoluene provided by the present invention can be carried out under mild conditions, and the conversion rate and selectivity of the reaction have been greatly improved. [Brief explanation of the drawing] 【0042】 [Figure 1] This is an SEM image of the cobalt and chromium co-doped manganese oxide catalyst (S1) prepared in Example 1. [Figure 2] This is a TEM image of the cobalt and chromium co-doped manganese oxide catalyst (S1) prepared in Example 1. [Modes for carrying out the invention] 【0043】 The present invention will be described in further detail below with reference to the drawings and specific examples. However, the following examples are illustrative of the present invention and do not limit the technical scope of the invention. In the following examples, operating conditions that are not specifically mentioned shall be those of normal use or those recommended by the manufacturer of the commercially available reagents. Unless otherwise specified, room temperature means 25°C. [Examples] 【0044】 Step 1: Preparation of manganese oxide-supported cobalt-chromium catalyst The catalyst material is prepared using a high-temperature reflux method. 7.08 g of potassium permanganate and 14.7 g of manganese tetrahydrate acetate are weighed together, and the metal loading is adjusted to 6 wt%, with a Co to Cr mass ratio of 1:1. 1.28 g of cobalt acetate and 3.29 g of chromium nonahydrate nitrate are dissolved in 200 mL of deionized water and thoroughly stirred at 90°C to form a homogeneous mixed solution. Next, add 3.5 mL of nitric acid to this mixed solution and continue stirring under reflux for 24 hours. After the reaction is complete, the solid mixture is filtered by suction and dried overnight at 90°C. The dried catalyst precursor is collected and heated in a muffle furnace at a heating rate of 2°C / min to 400°C, where it is held for 4 hours to calcinate. The catalyst obtained in this way is CoCr@MnO X Let's name it (S1). 【0045】 Step 2: Catalytic oxidation reaction Add the S1 catalyst (0.05 g) and parachlorotoluene (1 mL, 1.08 g) prepared above to a 50 mL three-necked flask, then add 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid (40 wt%). This mixture is reacted at 100°C with an oxygen flow rate of 80 mL / min for 12 hours. Analysis of the reaction products by gas chromatography revealed that the conversion rate of p-chlorotoluene was 94.8%, the selectivity of p-chlorobenzaldehyde was 94.3%, and the yield was 89.5%. Comparative Example 1 【0046】 Step 1: Preparation of manganese oxide-supported cobalt-chromium catalyst (gel method) Unlike Example 1, the catalyst CoCr@MnO was prepared using the gel method. X (D1) was prepared. 14.7 g of manganese tetrahydrate acetate was weighed to a metal load of 6 wt% and a Co to Cr mass ratio of 1:1. 1.28 g of cobalt acetate and 3.29 g of chromium nonahydrate nitrate were dissolved in 50 mL of anhydrous ethanol and stirred thoroughly at 60°C to prepare a purple-red mixed solution. Next, 3.24 g of oxalic acid solution dissolved in 150 mL of deionized water was added to the mixed solution and the mixture was magnetically stirred for a further 1 hour. 【0047】 After the reaction was complete, the solid mixture was filtered by suction, washed, and dried overnight at 60°C. The resulting catalyst precursor was heated in a muffle furnace to 400°C at a heating rate of 2°C / min and calcined for 4 hours. The resulting catalyst was converted to CoCr@MnO X Let's name it (D1). 【0048】 Step 2: Catalytic oxidation reaction In a 50 mL three-necked flask, the above D1 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid were added, and the mixture was reacted at 100 °C with an oxygen flow rate of 80 mL / min for 12 hours. Gas chromatography analysis showed that the conversion rate of parachlorotoluene was 76.4%, the selectivity of parachlorobenzaldehyde was 82.5%, and the yield was 63.0%. Comparative Example 2 【0049】 Step 1: Preparation of manganese oxide-supported cobalt-chromium catalyst (coprecipitation method) Unlike Example 1, the catalyst CoCr@MnO was obtained by coprecipitation. X (D2) was prepared. 7.08 g of potassium permanganate and 14.7 g of manganese tetrahydrate acetate were weighed to a metal load of 6 wt% and a Co to Cr mass ratio of 1:1. 1.28 g of cobalt acetate and 3.29 g of chromium nonahydrate nitrate were dissolved in 200 mL of deionized water to prepare a mixed solution. After stirring thoroughly at 90°C, 5 mL of 1 mol / L NaOH solution was added as a precipitant, and the mixture was stirred for a further 24 hours. 【0050】 The solid mixture was then filtered by suction, washed, and dried overnight at 90°C. The resulting catalyst precursor was heated to 400°C at a rate of 2°C / min and calcined for 4 hours. The resulting catalyst was converted to CoCr@MnO X Let's name it (D2). 【0051】 Step 2: Catalytic oxidation reaction D2 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid were added to a three-necked flask and reacted for 12 hours at 100°C with an oxygen flow rate of 80 mL / min. Analysis by gas chromatography showed that the conversion rate of parachlorotoluene was 46.2%, the selectivity of parachlorobenzaldehyde was 62.1%, and the yield was 28.7%. Comparative Example 3 【0052】 Step 1: Preparation of manganese oxide catalyst (undoped) In a method similar to Example 1, manganese oxide catalyst (MnO) was prepared without doping with cobalt and chromium. X Solution D3) was prepared. 7.08 g of potassium permanganate and 14.7 g of manganese tetrahydrate acetate were dissolved in 200 mL of deionized water and stirred thoroughly at 90°C to form a mixed solution. Next, 3.5 mL of nitric acid was added and stirring was continued under reflux for 24 hours. After the reaction was complete, the solid mixture was washed by suction filtration and dried overnight at 90°C. The resulting precursor was heated in a muffle furnace at 2°C / min up to 400°C and calcined for 4 hours. The resulting catalyst was converted to MnO X Let's name it (D3). 【0053】 Step 2: Catalytic oxidation reaction D3 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid were added to a 50 mL three-necked flask, and the reaction was carried out at 100 °C with an oxygen flow rate of 80 mL / min for 12 hours. Gas chromatography analysis revealed a conversion rate of 90.1%, a selectivity of 67.9%, and a yield of 61.2%. [Examples] 【0054】 Step 1: Preparation of Manganese Oxide-Supported Cobalt Chromium Catalyst (CoCr2@MnO X , S2) Prepared by the high-temperature reflux method. Weigh 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate, with a metal loading of 6 wt% and Co:Cr = 1:2. Dissolve 1.28 g of cobalt acetate and 6.58 g of chromium nitrate nonahydrate in 200 mL of deionized water to obtain a mixed solution. Add 3.5 mL of nitric acid to this and stir for 24 hours under reflux conditions. After the reaction is completed, the solid mixture is suction filtered, washed, dried at 90 °C, and then calcined at a heating rate of 2 °C / min to 400 °C for 4 hours. The obtained catalyst is named CoCr2@MnO X (S2). 【0055】 Step 2: Catalytic Oxidation Reaction Add S2 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid, and carry out the reaction at 100 °C with an oxygen flow rate of 80 mL / min for 12 hours. As the analysis results, a conversion rate of 92.1%, a selectivity of 81%, and a yield of 74.6% were obtained. 【Example】 【0056】 Step 1: Preparation of Manganese Oxide-Supported Cobalt Chromium Catalyst (Co2Cr@MnO X , S3) Similarly, using the high-temperature reflux method, with a metal loading of 6 wt% and Co:Cr = 2:1, use of 2.56 g of cobalt acetate and 3.29 g of chromium nitrate nonahydrate, and the other conditions were prepared in the same manner as in Example 1. The obtained catalyst was named Co2Cr@MnO X (S3). 【0057】 Step 2: Catalytic Oxidation Reaction Using the S3 catalyst (0.05 g) and raw materials, the reaction was carried out at 100 °C under an oxygen flow rate of 80 mL / min for 12 hours. The conversion rate was 67.5%, the selectivity was 92.1%, and the yield was 62.1%. 【Example】 【0058】 Step 1: Manganese oxide-supported cobalt catalyst (Co@MnO X Preparation of S4) Prepared by high-temperature reflux method. 7.08 g of potassium permanganate and 14.7 g of manganese tetrahydrate acetate were used, and 1.28 g of cobalt acetate was added to achieve a metal loading of 6 wt%. The rest was prepared in the same manner as in Example 1, and Co@MnO X It was named (S4). 【0059】 Step 2: Catalytic oxidation reaction Using S4 catalyst (0.05 g), the reaction was carried out at 100°C under an oxygen flow rate of 80 mL / min for 12 hours. A conversion rate of 85.5%, a selectivity of 71.9%, and a yield of 61.5% were obtained. [Examples] 【0060】 Step 1: Manganese oxide-supported chromium catalyst (Cr@MnO X Preparation of S5) Prepared by high-temperature reflux. 7.08 g of potassium permanganate and 14.7 g of manganese tetrahydrate acetate are weighed, and 3.29 g of chromium nonahydrate (assuming a metal loading of 6 wt%) is dissolved in 200 mL of deionized water to prepare a mixed solution. The mixture is stirred at 90°C, 3.5 mL of nitric acid is added, and reflux stirring is continued for 24 hours. The resulting solid mixture is filtered and washed, dried at 90°C, and then calcined at a rate of 2°C / min to 400°C for 4 hours. The resulting catalyst is named Cr@MnOX(S5). 【0061】 Step 2: Catalytic oxidation reaction S5 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL acetic acid, 2 mL water, and 50 μL hydrobromic acid were added to a three-necked flask and reacted for 12 hours at 100°C with an oxygen flow rate of 80 mL / min. A conversion rate of 87.6%, a selectivity of 75.2%, and a yield of 65.8% were obtained. [Examples] 【0062】 Using the S1 catalyst (0.05 g), the amount of HBr added was reduced to 25 μL. The reaction was carried out under the same conditions as in Example 1 (100°C, oxygen flow rate 80 mL / min, 12 hours), yielding a conversion rate of 34%, a selectivity of 87.5%, and a yield of 29.8%. [Examples] 【0063】 Using the S1 catalyst (0.05 g), the amount of HBr added was increased to 75 μL. The reaction was carried out under the same conditions as in Example 1, yielding a conversion rate of 29.8%, a selectivity of 74.2%, and a yield of 22.1%. [Examples] 【0064】 Using S1 catalyst (0.05g), the reaction temperature was changed to 90°C. Otherwise, the procedure was the same as in Example 1, yielding a conversion rate of 87.6%, a selectivity of 73.7%, and a yield of 64.6%. [Examples] 【0065】 Using S1 catalyst (0.05g), the reaction temperature was set to 80°C. Under the same conditions as before, a conversion rate of 92%, a selectivity of 64.6%, and a yield of 59.4% were obtained. [Examples] 【0066】 Using S1 catalyst (0.05g), the reaction temperature was set to 110°C. Under the same conditions as before, a conversion rate of 98.1%, a selectivity of 79.1%, and a yield of 77.5% were obtained. [Examples] 【0067】 Using S1 catalyst (0.05g), 8mL of acetic acid, and 2mL of water, under the same conditions as before, a conversion rate of 99%, a selectivity of 75.3%, and a yield of 74.5% were obtained. [Examples] 【0068】 Using S1 catalyst (0.05g), 12mL of acetic acid, and 2mL of water, under the same conditions as before, a conversion rate of 90.9%, a selectivity of 85.2%, and a yield of 77.5% were obtained. [Examples] 【0069】 Using S1 catalyst (0.05 g), the amount of water was reduced to 1 mL. Under the same conditions as before, a conversion rate of 31%, a selectivity of 71.9%, and a yield of 22.3% were obtained. [Examples] 【0070】 Using S1 catalyst (0.05g), the oxygen flow rate was changed to 60mL / min. Under the same conditions as before, a conversion rate of 92.8%, a selectivity of 74.4%, and a yield of 69.1% were obtained. [Examples] 【0071】 Using S1 catalyst (0.05g), the oxygen flow rate was changed to 100mL / min. Under the same conditions as before, a conversion rate of 99%, a selectivity of 78.9%, and a yield of 78.1% were obtained. 【0072】 Furthermore, a person skilled in the art who has read the above description of the present invention will understand that various improvements or modifications can be made to the present invention, and that these equivalent forms are also included within the scope of the claims of the present invention.

Claims

[Claim 1] A method for producing parachlorobenzaldehyde by selective oxidation of parachlorotoluene, comprising the steps of uniformly mixing a manganese oxide-supported cobalt-chromium catalyst, a solvent, a brominated initiator, and parachlorotoluene, introducing oxygen at 60 to 110°C to carry out an oxidation reaction, and obtaining parachlorobenzaldehyde, The reaction temperature for the oxidation reaction is 80 to 110°C. The solvent is a mixture of acetic acid and water, with a volume ratio of acetic acid to water of 3 to 8:

1. The volume ratio of parachlorotoluene to brominated initiator is 1 mL / 40-60 μL. The method for producing the manganese oxide-supported cobalt-chromium catalyst is as follows: The process involves dissolving manganese salt and metal salts of cobalt and chromium in deionized water, stirring, and obtaining a mixed solution. The process involves adding acid to the mixed solution, heating and stirring to carry out a reaction, and after the reaction is complete, filtering, drying and calcining to obtain the manganese oxide-supported cobalt-chromium catalyst, Includes, The amount of cobalt and chromium metal elements supported is 2 to 15 wt% relative to the manganese elements in the carrier, and the mass ratio of the supported cobalt and chromium metal elements is 1:3 to 3:

1. The acid is one or more selected from hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid. The reaction time for the heating and stirring reaction after acid addition is 12 to 48 hours, and the heating temperature is 70 to 120°C. When the manganese salt is a combination of potassium permanganate and manganese acetate, the mass-volume ratio of the acid to potassium permanganate is 0.25 to 1.13 mL / g. A method for producing parachlorobenzaldehyde by selective oxidation of parachlorotoluene, characterized by the following: [Claim 2] The manganese salt is one or more selected from permanganate, chloride, acetate, acetylacetonate, and nitrate. The manufacturing method according to claim 1, characterized in that the metal salts of cobalt and chromium are one or more selected from chlorides, acetates, acetylacetonates, and nitrates, respectively. [Claim 3] The drying temperature is 80-100°C, and the drying time is 8-10 hours. The manufacturing method according to claim 1, characterized in that the firing temperature is 400 to 500°C and the firing time is 4 to 5 hours. [Claim 4] The solvent is one or more selected from acetic acid, acetonitrile, acetic anhydride, and water. The manufacturing method according to claim 1, characterized in that the bromine-based initiator is one or more selected from KBr, HBr, and NaBr.

Images