Manganese oxide supported cobalt chromium catalyst, its preparation method 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 technical field of organic catalysts, and more specifically to a manganese oxide-supported cobalt chromium catalyst and a method for producing the same, as well as 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 the fields of pharmaceuticals, dye intermediates, pesticides, etc. It is used in the synthesis of pharmaceuticals such as fennalol and aminophen amino acids, and plant growth regulators such as uniconazole and multi-potency azole.

[0003] In the conventional chlorination hydrolysis method, the reaction is carried out using chlorine gas and soluble metal salts, but this method has the disadvantage of being strict on equipment conditions and producing wastewater that pollutes the environment.With the development of green chemistry, environmentally friendly oxidizing agents such as hydrogen peroxide (H2O2) and oxygen (O2) are attracting attention in the fine chemical industry.

[0004] While hydrogen peroxide is important for reducing waste emissions and realizing 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 active research is being conducted into the direct oxidation of parachlorotoluene as an oxidizing agent to produce parachlorobenzaldehyde.

[0005] However, this process requires high performance from the catalyst, and therefore the development of highly active and highly selective catalysts has become a focus of research.

[0006] Regarding this reaction pathway, Cai Minmin et al. ("Production of parachlorobenzaldehyde from parachlorotoluene by air oxidation", Chemical World, 2002) investigated oxidation reactions in air and oxygen atmospheres, and reported that the yield when oxygen was used was 28%, which was superior to air oxidation, but the reaction activity was still low.

[0007] Toyasu et al. (Catalysis Communications 8, 2007, pp.1279-1283) produced parachlorobenzaldehyde by oxygen oxidation of parachlorotoluene using acetic acid-water as a solvent and cobalt and manganese salts as catalysts under atmospheric pressure and low temperature conditions, achieving a conversion of 33.7% and a selectivity of 66.6%. While this method has the advantages of a simple process and low cost, it has problems such as the difficulty of separating and recovering the homogeneous catalyst and low selectivity to the target product.

[0008] Patent document CN101138729A reports that the active metal components cobalt and manganese were supported on Al2O3 and subjected to liquid phase oxidation, and that by adjusting the oxygen flow rate, temperature, catalyst composition ratio, etc., a conversion rate of 43.7% was achieved; however, there is still a need to improve catalytic activity.

[0009] The process for producing parachlorobenzaldehyde by liquid-phase oxygen oxidation of parachlorotoluene has the advantages of simple and mild operating conditions, minimal contamination, and easy separation and reuse of raw materials and solvents. Each of the above studies has attempted to improve this reaction using different approaches, but there are still issues that need to be resolved.

[0010] Specifically, there are problems with the low utilization efficiency of the oxidant, insufficient catalytic activity, and low selectivity due to the tendency to produce by-products such as parachlorobenzyl alcohol, parachlorobenzoic acid, and 4-chlorobenzyl acetate. Furthermore, homogeneous catalysts using manganese salts produce a large amount of wastewater, making it difficult to reuse the catalyst.

[0011] Therefore, the development of heterogeneous catalysts suitable for this reaction and further improvement of the reaction activity and selectivity for the target product remain important research topics. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] China Patent Publication No. CN101138729A [Non-patent literature]

[0013] [Non-Patent Document 1] Parachlorobenzaldehyde production from parachlorotoluene by air oxidation, Chemical World, 2002 [Non-patent document 2] Catalysis Communications 8, 2007, pp.1279-1283 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention addresses the problems of low catalytic activity and low selectivity in existing technologies in the process for producing parachlorobenzaldehyde, and provides a supported cobalt chromium catalyst for highly selectively producing parachlorobenzaldehyde by oxidizing parachlorotoluene, and a method for producing the same.

[0015] In this invention, by adjusting the active components and their ratios of the catalyst and optimizing the reaction conditions, it is possible to produce with high selectivity. Furthermore, the production process of this catalyst is simple and easy to reuse after separation, washing, drying, and high-temperature calcination, making it suitable for industrial production. [Means for solving the problem]

[0016] The technical means according to the present invention are as follows: This is a method for producing a catalyst in which cobalt and chromium are supported on manganese oxide. Manganese salt and precursor metal salts of cobalt and chromium are dissolved in deionized water to obtain a mixed solution, and then acid is added and the reaction is carried out by heating and stirring. After the reaction is complete, the catalyst is filtered, dried, and calcined to obtain the desired cobalt-chromium supported catalyst.

[0017] Specifically, the process includes the following steps: (1) A certain amount of manganese salt is weighed out, and metal salt precursors of cobalt and chromium are also weighed out so as to obtain a predetermined loading amount, and these are dissolved in deionized water to prepare a mixed solution.

[0018] (2) After the substance is sufficiently dissolved at a certain temperature, a certain amount of acid is added and the mixture is heated and stirred continuously.

[0019] (3) After the reaction is complete, the solid mixture is suction filtered, washed, dried, and calcined to obtain the desired catalyst as a deep brown powder.

[0020] In step (1), the manganese salt is selected from one or more of manganate, chloride, acetate, acetylacetonate, and nitrate, and preferably includes two or more of manganate (Na or K), manganese acetate, and manganese nitrate.

[0021] The metal salts of cobalt and chromium are also selected from one or more of chlorides, acetates, acetylacetonates and nitrates, with acetates and nitrates being particularly preferred.

[0022] The precursor of the cobalt salt is selected from cobalt chloride, cobalt acetate, cobalt acetylacetonate, and cobalt nitrate, with cobalt acetate and cobalt nitrate being particularly preferred.

[0023] The precursor of the chromium salt is similarly selected from chromium chloride, chromium acetate, chromium acetylacetonate, and chromium nitrate, with chromium acetate and chromium nitrate being particularly preferred.

[0024] As a specific example, the manganese salt is a mixture of a higher manganate (K or Na) and manganese acetate, with the molar ratio of the two being 1:1 to 2, more preferably 1:1 to 1:5.

[0025] In step (1), the loading of Co and Cr is preferably 2 to 15 wt% based on the mass of Mn in the support, and based on the Mn contained in the potassium manganate, the loading is 4 to 10%, more preferably 4 to 8%, and even more preferably 5 to 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 Co salt concentration 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-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 to 700°C, more preferably 400 to 500°C, and the firing time is 3 to 6 hours, more preferably 4 to 5 hours.

[0032] The present invention also provides a supported cobalt chromium catalyst obtained by the above production method. The catalyst is a multi-component metal oxide in which predetermined amounts of cobalt and chromium are supported on a manganese oxide support.

[0033] Preferably, the amounts of cobalt and chromium supported in the catalyst are each 2 to 15 wt %.

[0034] Furthermore, the present invention also relates to the use of the manganese oxide-supported cobalt chromium catalyst in the highly selective oxidation of parachlorotoluene to produce parachlorobenzaldehyde.

[0035] The overall concept of the present invention provides a method for obtaining parachlorobenzaldehyde by mixing the catalyst, a solvent, a 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, and the volume ratio of acetic acid to water is 3 to 8:1, preferably 4 to 6:1, and parachlorotoluene to solvent is 1:3 to 14, preferably 1:5 to 14, and more preferably 1:8 to 14.

[0037] The bromine-based initiator is preferably one of KBr, HBr, and 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 bromine-based 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 to 0.1), preferably 1:(0.03 to 0.1), and more preferably 1:(0.04 to 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 advantageous effects compared to the prior art. 1. The present invention provides a supported cobalt chromium catalyst, which can be produced by a simple method, the raw materials are readily available and low cost, and the catalyst can be easily separated and recovered. 2. By introducing cobalt and manganese into the cerium oxide catalyst, the specific surface area of ​​the catalyst increases, and the catalytic activity of the catalyst in the oxidative denitration reaction is enhanced. 3. The process 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 are significantly improved. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is an SEM image of the cobalt and chromium co-doped manganese oxide catalyst (S1) prepared in Example 1. [Figure 2] 1 is a TEM image of the cobalt and chromium co-doped manganese oxide catalyst (S1) prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention will be described in more detail below with reference to the drawings and specific examples. However, the following examples are merely illustrative of the present invention and are not intended to limit the technical scope of the invention. Unless otherwise specified, the operating conditions in the following examples are standard conditions or those recommended by manufacturers of commercially available reagents. Unless otherwise specified, room temperature refers to 25°C. [Example]

[0044] Step 1: Preparation of manganese oxide-supported cobalt chromium catalyst The catalyst material was prepared using the high-temperature reflux method. 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate were weighed out. Furthermore, to achieve a metal loading of 6 wt% and a Co:Cr mass ratio of 1:1, 1.28 g of cobalt acetate and 3.29 g of chromium nitrate nonahydrate were dissolved in 200 mL of deionized water and stirred thoroughly at 90 °C to form a homogeneous mixture. Next, 3.5 mL of nitric acid is added to this mixed solution, and stirring is continued under reflux for 24 hours. After the reaction is complete, the solid mixture is filtered off with suction and dried at 90°C overnight. The dried catalyst precursor is collected and calcined in a muffle furnace by heating it up to 400°C at a rate of 2°C / min and holding it for 4 hours. The catalyst thus obtained was CoCr@MnO X Name it (S1).

[0045] Step 2: Catalytic oxidation reaction In a 50 mL three-neck flask, add the S1 catalyst (0.05 g) prepared above and parachlorotoluene (1 mL, 1.08 g), and then add 10 mL of acetic acid, 2 mL of water, and 50 μL of hydrobromic acid (concentration 40 wt%). This mixture is reacted for 12 hours under conditions of 100°C and an oxygen flow rate of 80 mL / min. The reaction product was analyzed by gas chromatography, and it was found that the conversion of parachlorotoluene was 94.8%, the selectivity for parachlorobenzaldehyde was 94.3%, and the yield was 89.5%.

[0046] Step 1: Preparation of manganese oxide-supported cobalt chromium catalyst (gel method) Unlike Example 1, the catalyst CoCr@MnO was prepared by the gel method. XPreparation (D1) was prepared. 14.7 g of manganese acetate tetrahydrate was weighed out to a metal loading of 6 wt% with a Co:Cr mass ratio of 1:1. 1.28 g of cobalt acetate and 3.29 g of chromium nitrate nonahydrate were dissolved in 50 mL of absolute 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 magnetically stirred for an additional hour.

[0047] After the reaction was completed, the solid mixture was suction filtered, washed, and dried overnight at 60°C. The resulting catalyst precursor was heated to 400°C at a heating rate of 2°C / min in a muffle furnace and calcined for 4 hours. The resulting catalyst was CoCr@MnO X Name it (D1).

[0048] Step 2: Catalytic oxidation reaction In a 50 mL three-neck flask, the above catalyst D1 (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 for 12 hours at 100°C and an oxygen flow rate of 80 mL / min. Gas chromatography analysis showed that the conversion of parachlorotoluene was 76.4%, the selectivity to 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 prepared by the coprecipitation method. X (D2) was prepared. 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate were weighed out to a metal loading of 6 wt% with a Co:Cr mass ratio of 1:1. 1.28 g of cobalt acetate and 3.29 g of chromium nitrate nonahydrate were dissolved in 200 mL of deionized water to prepare a mixed solution. After thorough stirring at 90°C, 5 mL of 1 mol / L NaOH solution was added as a precipitant, and the mixture was stirred for an additional 24 hours.

[0050] The solid mixture was then suction filtered, washed, and dried at 90°C overnight. 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 CoCr@MnO X 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-neck 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 of parachlorotoluene was 46.2%, the selectivity to parachlorobenzaldehyde was 62.1%, and the yield was 28.7%. Comparative Example 3

[0052] Step 1: Preparation of manganese oxide catalyst (undoped) In a manner similar to Example 1, a manganese oxide catalyst (MnO) was prepared without doping with cobalt or chromium. X , D3) was prepared. 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate 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 completed, the solid mixture was suction filtered, washed, and dried at 90°C overnight. The obtained precursor was heated to 400°C at a rate of 2°C / min in a muffle furnace and calcined for 4 hours. The obtained catalyst was treated as MnO X 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-neck flask and reacted at 100 °C with an oxygen flow rate of 80 mL / min for 12 hours. Gas chromatography analysis revealed a conversion of 90.1%, a selectivity of 67.9%, and a yield of 61.2%. [Example]

[0054] First step: Manganese oxide supported cobalt chromium catalyst (CoCr@MnO X , S2) Preparation Prepared by high-temperature reflux. Weigh out 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate to achieve a metal loading of 6 wt% with a Co:Cr ratio of 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. To this is added 3.5 mL of nitric acid, and the mixture is stirred under reflux conditions for 24 hours. After the reaction is complete, the solid mixture is suction filtered, washed, dried at 90°C, and then heated to 400°C at a rate of 2°C / min and calcined for 4 hours. The resulting catalyst was CoCr2@MnO X Name it (S2).

[0055] Step 2: Catalytic oxidation reaction The S2 catalyst (0.05 g), parachlorotoluene (1 mL, 1.08 g), 10 mL acetic acid, 2 mL water, and 50 μL hydrobromic acid were added and the reaction was carried out at 100 °C with an oxygen flow rate of 80 mL / min for 12 hours. The analytical results showed a conversion of 92.1%, a selectivity of 81%, and a yield of 74.6%. [Example]

[0056] First step: Manganese oxide supported cobalt chromium catalyst (CoCr@MnO X , S3) Preparation Similarly, a high-temperature reflux method was used, with a metal loading of 6 wt% and a Co:Cr ratio of 2:1, and 2.56 g of cobalt acetate and 3.29 g of chromium nitrate nonahydrate were used, with the other conditions being the same as in Example 1. The resulting catalyst was CoCr@MnO X It was named (S3).

[0057] Step 2: Catalytic oxidation reaction Using S3 catalyst (0.05 g) and the raw material, the reaction was carried out at 100°C under an oxygen flow rate of 80 mL / min for 12 hours. The conversion was 67.5%, the selectivity was 92.1%, and the yield was 62.1%. [Example]

[0058] First step: Manganese oxide supported cobalt catalyst (Co@MnO X , S4) Preparation Prepared by high-temperature reflux. 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate were used, and 1.28 g of cobalt acetate was added to achieve a metal loading of 6 wt%. Other preparations were the same 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 with an oxygen flow rate of 80 mL / min for 12 hours. The conversion was 85.5%, the selectivity was 71.9%, and the yield was 61.5%. [Example]

[0060] First step: Manganese oxide supported chromium catalyst (Cr@MnO X , S5) Preparation Prepared by high-temperature reflux. 7.08 g of potassium permanganate and 14.7 g of manganese acetate tetrahydrate were weighed, and 3.29 g of chromium nitrate nonahydrate (6 wt% metal loading) was dissolved in 200 mL of deionized water to prepare a mixed solution. The mixture was stirred at 90°C, 3.5 mL of nitric acid was added, and the mixture was refluxed and stirred for an additional 24 hours. The resulting solid mixture was filtered, washed, dried at 90°C, and then heated to 400°C at a rate of 2°C / min and calcined for 4 hours. The resulting catalyst was designated 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-neck flask and reacted at 100°C with an oxygen flow rate of 80 mL / min for 12 hours. The conversion was 87.6%, the selectivity was 75.2%, and the yield was 65.8%. [Example]

[0062] The reaction was carried out under the same conditions as in Example 1 (100°C, oxygen flow rate 80 mL / min, 12 hours) using catalyst S1 (0.05 g) and reducing the amount of HBr added to 25 μL, resulting in a conversion of 34%, a selectivity of 87.5%, and a yield of 29.8%. [Example]

[0063] The reaction was carried out under the same conditions as in Example 1 except that the S1 catalyst (0.05 g) was used and the amount of HBr added was increased to 75 μL, resulting in a conversion of 29.8%, a selectivity of 74.2%, and a yield of 22.1%. [Example]

[0064] The S1 catalyst (0.05 g) was used, and the reaction temperature was changed to 90° C. Other conditions were the same as in Example 1, and a conversion rate of 87.6%, a selectivity of 73.7%, and a yield of 64.6% were obtained. [Example]

[0065] The catalyst S1 (0.05 g) was used, and the reaction temperature was set to 80° C. Under the same other conditions, a conversion rate of 92%, a selectivity of 64.6%, and a yield of 59.4% were obtained. [Example]

[0066] The catalyst S1 (0.05 g) was used, and the reaction temperature was set to 110° C. Under the same other conditions, a conversion rate of 98.1%, a selectivity of 79.1%, and a yield of 77.5% were obtained. [Example]

[0067] Using catalyst S1 (0.05 g), 8 mL of acetic acid, and 2 mL of water, the conversion was 99%, the selectivity was 75.3%, and the yield was 74.5% under the same conditions. [Example]

[0068] Using catalyst S1 (0.05 g), 12 mL of acetic acid, and 2 mL of water, the conversion was 90.9%, the selectivity was 85.2%, and the yield was 77.5% under the same conditions. [Example]

[0069] Using catalyst S1 (0.05 g) and reducing the amount of water to 1 mL, the conversion was 31%, the selectivity was 71.9%, and the yield was 22.3%. [Example]

[0070] Using catalyst S1 (0.05 g), the oxygen flow rate was changed to 60 mL / min. Under the same conditions, a conversion of 92.8%, a selectivity of 74.4%, and a yield of 69.1% were obtained. [Example]

[0071] Using catalyst S1 (0.05 g), the oxygen flow rate was changed to 100 mL / min. Under the same conditions, a conversion rate of 99%, a selectivity of 78.9%, and a yield of 78.1% were obtained.

[0072] It will be understood that those skilled in the art who have read the above description of the present invention may make various improvements or modifications to the present invention, and that equivalent forms thereof are also within the scope of the claims of the present invention.

Claims

1. dissolving manganese salt and metal salt precursors of cobalt and chromium in deionized water and stirring to obtain a mixed solution; adding an acid to the mixed solution, and carrying out a reaction by heating and stirring; and after completion of the reaction, filtering, drying and calcining the resulting mixture to obtain the cobalt chromium supported catalyst; 2. A method for producing a manganese oxide-supported cobalt chromium catalyst, comprising:

2. the manganese salt is one or more selected from permanganate, chloride, acetate, acetylacetonate, and nitrate; 2. The method according to claim 1, wherein the metal salt precursors of cobalt and chromium are one or more selected from the group consisting of chlorides, acetates, acetylacetonates, and nitrates.

3. 2. The method according to claim 1, wherein the amounts of the metal elements cobalt and chromium supported are each 2 to 15 wt % relative to the manganese element in the support, and the mass ratio between the two is 1:3 to 3:

1.

4. The stirring time after the addition of the acid is 12 to 48 hours, and the heating temperature is 70 to 120°C. the acid is one or more selected from hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid; 2. The method according to claim 1, wherein 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.

5. The drying temperature is 80 to 100°C, and the drying time is 8 to 10 hours.

2. The method according to claim 1, wherein the firing temperature is 400 to 500° C. and the firing time is 4 to 5 hours.

6. A manganese oxide-supported cobalt chromium catalyst obtained by the production method according to any one of claims 1 to 5.

7. A method for producing parachlorobenzaldehyde by selective oxidation of parachlorotoluene, comprising uniformly mixing the manganese oxide-supported cobalt chromium catalyst according to claim 6, a solvent, a bromine-based initiator, and parachlorotoluene, and introducing oxygen at 60 to 110°C to carry out an oxidation reaction to obtain parachlorobenzaldehyde.

8. the solvent is one or more selected from acetic acid, acetonitrile, acetic anhydride, and water, 8. The method according to claim 7, wherein the bromine-based initiator is one or more selected from the group consisting of KBr, HBr, and NaBr.

9. the volume ratio of the parachlorotoluene to the bromine-based initiator is 1 mL / 20 to 100 μL; the bromine-based initiator is hydrobromic acid having a concentration of 30% to saturation, The oxygen flow rate is 20 to 100 mL / min, The mass ratio of parachlorotoluene to manganese oxide-supported cobalt chromium catalyst is 1.0 (0.01 to 0.1), The method according to claim 7, wherein the reaction time is 6 to 14 hours.

10. The reaction temperature is 80 to 110°C, the solvent is a mixture of acetic acid and water, and the volume ratio of acetic acid to water is 3 to 8:1; 8. The method according to claim 7, wherein the volume ratio of parachlorotoluene to the bromine-based initiator is 1 mL / 40 to 60 μL.

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