Catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane, preparation method and application thereof

Abstract

The present invention discloses a method for preparing a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane, comprising the following steps: (1) under certain reaction conditions, first weighing a nitrogen source, coal gangue (dealuminized) powder, and a solvent and mechanically stirring the mixture to prepare a mixture; (2) under certain conditions, sequentially drying and calcining the mixture to obtain a catalyst precursor; and (3) etching, washing, and drying the catalyst precursor obtained in step (2) to obtain a catalyst. The conventional process for directly sulfurizing tetrahydrofuran to synthesize tetrahydrothiophene uses a heteropolyacid catalyst, which has the main disadvantages of being expensive catalysts and having a high catalytic reaction temperature (270-290°C). The catalyst-catalyzed process for synthesizing tetrahydrothiophene from 1,4-dibromobutane provided by the present invention can effectively overcome the technical problems of high reaction temperature and expensive catalysts.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular relates to a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane, a preparation method and application thereof. Background Art

[0002] Tetrahydrothiophene (THT) is an important sulfur-containing saturated heterocyclic compound. Due to its distinctive odor, it is widely used as an odorant and warning agent in natural gas. Natural gas itself is colorless and odorless, and once leaked, it cannot be detected, which can easily lead to accidents. Currently, according to international standards, tetrahydrothiophene must be used as an odorant for city gas, natural gas and other gases, replacing odorants such as ethyl mercaptan that were previously used. At the same time, tetrahydrothiophene can also be used as an intermediate for new pharmaceuticals, pesticides and additives for polymer synthetic materials, and can also be used in the formulation of dental and pharmaceutical primers. With the development and progress of science and technology, many application fields and functions of tetrahydrothiophene are constantly being developed, and domestic application demand is also gradually increasing.

[0003] The traditional process for directly sulfiding tetrahydrofuran to tetrahydrothiophene uses a heteropolyacid catalyst. The main drawbacks of this process include expensive catalysts and a relatively high reaction temperature (270-290°C). Therefore, the development of new, cost-effective catalysts and processes is a hot topic in tetrahydrothiophene production. Summary of the Invention

[0004] In response to the technical problems of expensive catalysts and high reaction temperatures (270-290°C) in the current catalytic synthesis of tetrahydrothiophene, the present invention proposes a method for preparing a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane. The catalyst exhibits excellent catalytic activity and selectivity during the tetrahydrothiophene synthesis process.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane comprises the following steps:

[0007] (1) Under certain reaction conditions, a nitrogen source, coal gangue (dealuminized) powder, and a solvent are weighed and mechanically stirred to prepare a mixture;

[0008] (2) Under certain conditions, the mixture is dried and calcined in sequence to obtain a catalyst precursor;

[0009] (3) Etching, washing and drying the catalyst precursor obtained in step (2) to obtain a catalyst.

[0010] Furthermore, in step (1), the nitrogen source, coal gangue (dealuminized) powder and solvent are mechanically stirred to prepare a mixture, the stirring temperature is 10-30°C, the stirring speed is 200-800r / min, and the stirring time is 5-120min, wherein the mass ratio of the nitrogen source to the solvent is (1-5):5, and the mass ratio of the coal gangue (dealuminized) to the solvent is (1-2):8.

[0011] Furthermore, the nitride is one of dicyandiamide, melamine, urea and hexamethylenetetramine.

[0012] Furthermore, the solvent is one of methanol, ethanol, water, ether and acetone.

[0013] Furthermore, in step (2), the mixture is dried and calcined in sequence to obtain a catalyst precursor. The drying temperature is 100-120°C, the drying time is 60-240 minutes, the calcination temperature is 450-750°C, the calcination time is 60-240 minutes, and the heating rate is 2-15°C / min.

[0014] Furthermore, the catalyst precursor of step (2) is etched, washed, and dried to obtain a catalyst. The etchant is an ammonium fluoride solution (20-80 wt%), the etching time is 1-3 days, the detergent is distilled water, and the washing is performed until neutral. The drying temperature is 100-120° C., and the drying time is 60-240 minutes.

[0015] The present invention also provides a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane, which is prepared by the above method.

[0016] The present invention also provides use of the catalyst in a catalytic synthesis of tetrahydrothiophene reaction, wherein 1,4-dibromobutane, potassium sulfide and the catalyst are added into a flask, the reaction temperature is 80-120° C., the reaction pressure is 0.2-1.0 MPa, and the reaction time is 60-240 min, wherein the mass ratio of the catalyst to the 1,4-dibromobutane is (1-3):10, and the mass ratio of the 1,4-dibromobutane to the potassium sulfide is (1-9):1.

[0017] The present invention has the following beneficial effects: The conventional process for directly sulfurizing tetrahydrofuran to tetrahydrothiophene uses a heteropolyacid catalyst, which suffers from the following major drawbacks: expensive catalysts and high reaction temperatures (270-290°C). The present invention's process for synthesizing tetrahydrothiophene from 1,4-dibromobutane using a catalyst effectively overcomes these technical issues. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this embodiment is as follows:

[0021] (1) Weigh 20 g of dicyandiamide, 10 g of coal gangue (dealuminized) powder and 80 g of ethanol and mechanically stir them to prepare a mixture at a stirring temperature of 20° C., a stirring speed of 500 r / min, and a stirring time of 5 min.

[0022] (2) 30 g of the mixture obtained in step (1) was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100° C., the drying time was 60 min, the calcination temperature was 550° C., the calcination time was 120 min, and the heating rate was 10° C. / min.

[0023] (3) Etching, washing and drying 25 g of the catalyst precursor obtained in step (2) to obtain catalyst 1; etching time with 20 wt% ammonium fluoride solution was 2 days; the detergent was distilled water, and the mixture was washed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0024] The application of catalyst 1 in the catalytic reaction of synthesizing tetrahydrothiophene from 1,4-dibromobutane is as follows:

[0025] 1,4-Dibromobutane, potassium sulfide, and Catalyst 1 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 240 minutes. The mass ratio of Catalyst 1 to 1,4-Dibromobutane was 3:10, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 5:1. The catalyst evaluation results are shown in Table 1.

[0026] Example 2

[0027] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this embodiment is as follows:

[0028] (1) Under certain reaction conditions, 30 g of melamine, 20 g of coal gangue (dealuminized) powder and 80 g of methanol were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0029] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0030] (3) Etching, washing and drying 25 g of the catalyst precursor obtained in step (2) to obtain catalyst 2; etching time with 20 wt% ammonium fluoride solution was 2 days; the detergent was distilled water, and the mixture was washed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0031] The application of catalyst 2 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane is as follows:

[0032] 1,4-Dibromobutane, potassium sulfide, and Catalyst 2 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Catalyst 2 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0033] Example 3

[0034] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this embodiment is as follows:

[0035] (1) Under certain reaction conditions, 35 g of hexamethylenetetramine, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0036] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0037] (3) Etching, washing and drying 25 g of the catalyst precursor obtained in step (2) to obtain catalyst 3; etching time with 20 wt% ammonium fluoride solution was 2 days; the detergent was distilled water, and the mixture was washed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0038] The application of catalyst 3 in the catalytic reaction of synthesizing tetrahydrothiophene from 1,4-dibromobutane is as follows:

[0039] 1,4-Dibromobutane, potassium sulfide, and Catalyst 3 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Catalyst 3 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0040] Example 4

[0041] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this embodiment is as follows:

[0042] (1) Under certain reaction conditions, 40 g of urea, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0043] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0044] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain catalyst 4; the etching time was 2 days using a 20 wt% ammonium fluoride solution; the detergent was distilled water, and the mixture was washed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0045] The application of catalyst 4 in the catalytic reaction of synthesizing tetrahydrothiophene from 1,4-dibromobutane is as follows:

[0046] 1,4-Dibromobutane, potassium sulfide, and Catalyst 4 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Catalyst 4 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 3:1. The catalyst evaluation results are shown in Table 1.

[0047] Example 5

[0048] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this embodiment is as follows:

[0049] (1) Under certain reaction conditions, 40 g of urea, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0050] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0051] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain catalyst 5. The etching time was 2 days using 80 wt% ammonium fluoride solution. The detergent was distilled water and the mixture was washed until neutral. The drying temperature was 120° C. and the drying time was 240 min.

[0052] The application of catalyst 5 in the catalytic reaction of synthesizing tetrahydrothiophene from 1,4-dibromobutane is as follows:

[0053] 1,4-Dibromobutane, potassium sulfide, and Catalyst 5 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Catalyst 5 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0054] Comparative Example 1

[0055] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this comparative example is as follows:

[0056] (1) Under certain reaction conditions, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0057] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0058] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain comparative catalyst 1; the etching time was 2 days using 80 wt% ammonium fluoride solution; the detergent was distilled water, and the washing was performed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0059] Comparative application of catalyst 1 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane, the steps are as follows:

[0060] 1,4-Dibromobutane, potassium sulfide, and Comparative Catalyst 1 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Comparative Catalyst 1 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0061] Comparative Example 2

[0062] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this comparative example is as follows:

[0063] (1) Under certain reaction conditions, 40 g of urea and 80 g of acetone were weighed and mechanically stirred to prepare a mixture at a stirring temperature of 30°C, a stirring speed of 500 r / min, and a stirring time of 120 min.

[0064] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0065] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain comparative catalyst 2; the etching time was 2 days with 80 wt% ammonium fluoride solution; the detergent was distilled water, and the washing was performed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0066] Comparative application of catalyst 2 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane, the steps are as follows:

[0067] 1,4-Dibromobutane, potassium sulfide, and Comparative Catalyst 2 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Comparative Catalyst 2 to 1,4-Dibromobutane was 1:5, and the mass ratio of 1,4-Dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0068] Comparative Example 3

[0069] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this comparative example is as follows:

[0070] (1) Under certain reaction conditions, 40 g of urea, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0071] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0072] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain comparative catalyst 3; the etching time was 2 days with 80 wt% ammonium fluoride solution; the detergent was distilled water, and the washing was performed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0073] Comparative application of catalyst 3 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane, the steps are as follows:

[0074] 1,4-Dibromobutane and Comparative Catalyst 3 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Comparative Catalyst 3 to 1,4-Dibromobutane was 1:5. The catalyst evaluation results are shown in Table 1.

[0075] Comparative Example 4

[0076] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this comparative example is as follows:

[0077] (1) Under certain reaction conditions, 40 g of urea and 20 g of coal gangue (dealuminized) powder were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30 °C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0078] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0079] (3) 25 g of the catalyst precursor obtained in step (2) was etched, washed and dried to obtain comparative catalyst 4. The etching time was 2 days using 80 wt% ammonium fluoride solution; the detergent was distilled water, and the solution was washed until neutral; the drying temperature was 120° C., and the drying time was 240 min.

[0080] Comparative application of catalyst 4 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane, the steps are as follows:

[0081] 1,4-Dibromobutane, potassium sulfide, and Comparative Catalyst 4 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Comparative Catalyst 4 to 1,4-dibromobutane was 1:5, and the mass ratio of 1,4-dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0082] Comparative Example 5

[0083] The preparation method of the catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in this comparative example is as follows:

[0084] (1) Under certain reaction conditions, 40 g of urea, 20 g of coal gangue (dealuminized) powder and 80 g of acetone were weighed and mechanically stirred to prepare a mixture. The stirring temperature was 30°C, the stirring speed was 500 r / min, and the stirring time was 120 min.

[0085] (2) Under certain conditions, 30 g of the mixture was dried and calcined in sequence to obtain a catalyst precursor. The drying temperature was 100 °C, the drying time was 60 min, the calcination temperature was 750 °C, the calcination time was 120 min, and the heating rate was 10 °C / min.

[0086] Comparative application of catalyst 5 in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane, the steps are as follows:

[0087] 1,4-Dibromobutane, potassium sulfide, and Comparative Catalyst 5 were added to a flask. The reaction temperature was 120°C, the reaction pressure was 1.0 MPa, and the reaction time was 60 minutes. The mass ratio of Comparative Catalyst 5 to 1,4-dibromobutane was 1:5, and the mass ratio of 1,4-dibromobutane to potassium sulfide was 2:1. The catalyst evaluation results are shown in Table 1.

[0088] Table 1

[0089]

[0090] Analysis of catalyst 5 and comparative catalyst 1 showed that the catalysts were prepared without a nitrogen source and were not Lewis base catalysts, and therefore had poor performance in the catalytic reaction of synthesizing tetrahydrothiophene from 1,4-dibromobutane.

[0091] Analysis of catalyst 5 and comparative catalyst 2 showed that the catalysts prepared without coal gangue (dealuminized) powder did not have multi-level pores in their materials, and therefore had poor performance in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane.

[0092] Catalyst 5 and comparative catalyst 3, analysis showed that the catalysts prepared by mechanical physical stirring had poor performance in the catalytic reaction of 1,4-dibromobutane to tetrahydrothiophene.

[0093] Catalyst 5 and comparative catalyst 4, analysis showed that without the participation of potassium sulfide as a catalyst promoter, the performance of the catalysts in the catalytic synthesis of tetrahydrothiophene from 1,4-dibromobutane was poor.

[0094] Analysis of catalyst 5 and comparative catalyst 5 showed that the catalysts were prepared without the ammonium fluoride etching process, and there were no multi-level pores in the materials, so the performance in catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane was poor.

[0095] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. Use of a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane in a catalytic synthesis of tetrahydrothiophene reaction, characterized in that: 1,4-dibromobutane, potassium sulfide and catalyst are added to a high-pressure catalytic reactor, the reaction temperature is 80-120°C, the reaction pressure is 0.2-1.0 MPa, and the reaction time is 60-240 min, wherein the mass ratio of catalyst to 1,4-dibromobutane is (1-3):10, and the mass ratio of 1,4-dibromobutane to potassium sulfide is (1-9):1; A method for preparing a catalyst for catalyzing the synthesis of tetrahydrothiophene from 1,4-dibromobutane comprises the following steps: (1) Under certain reaction conditions, a nitrogen source, dealuminated coal gangue powder, and a solvent are first weighed and mechanically stirred to prepare a mixture; (2) Under certain conditions, the mixture is dried and calcined in sequence to obtain a catalyst precursor; (3) Etching, washing and drying the catalyst precursor obtained in step (2) to obtain a catalyst.

2. The use according to claim 1, characterized in that: In the step (1), the mass ratio of the nitrogen source to the solvent is (1-5):5, and the mass ratio of the dealuminated coal gangue powder to the solvent is (1-2):

8.

3. The use according to claim 1, characterized in that: In the step (1), the mechanical stirring temperature is 10-30° C., the stirring speed is 200-800 r / min, and the stirring time is 5-120 min.

4. The use according to claim 1, characterized in that: In the step (1), the nitrogen source is dicyandiamide, melamine, urea or hexamethylenetetramine.

5. The use according to claim 1, characterized in that: The solvent in step (1) is one of methanol, ethanol, water, ether and acetone.

6. The use according to claim 1, characterized in that: In the step (2), the drying temperature is 100-120°C, the drying time is 60-240 min, the roasting temperature is 450-750°C, the roasting time is 60-240 min, and the roasting heating rate is 2-15°C / min.

7. The use according to claim 1, characterized in that: In step (3), the etchant is a 20-80 wt% ammonium fluoride solution, and the etching time is 1-3 days; the detergent is distilled water, and the washing is performed until neutral; The drying temperature is 100-120℃ and the drying time is 60-240min.

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