Method for adjusting TS-1 molecular sieve through plasma treatment technology and application

Abstract

The invention discloses a method for adjusting a TS-1 molecular sieve through a plasma treatment technology and application, and relates to the technical field of TS-1 molecular sieve treatment. The method comprises the following steps: S1, preprocessing a TS-1 sample; s2, selecting treatment gas, and presetting treatment conditions; s3, plasma treatment equipment is selected, and the pretreated TS-1 sample is laid according to a certain thickness; s4, processing according to a preset processing condition; and S5, post-processing and testing. The invention discloses a method for adjusting a TS-1 molecular sieve by a plasma treatment technology and application of the TS-1 molecular sieve, and the treated modified TS-1 molecular sieve has advantages in a Beckmann rearrangement reaction compared with a parent conversion rate and selectivity; loaded metals such as copper, cobalt and iron are used for a carbon dioxide and hydrogen reduction reaction, and compared with a matrix, the conversion rate and methanol selectivity are higher; the supported metals such as copper, cobalt, indium, platinum and palladium are used for photocatalytic reaction of carbon dioxide and water, and compared with a parent, the conversion rate and alcohol selectivity are higher.

Description

Technical Field

[0001] The invention relates to the technical field of material processing, and in particular to a method and application of regulating TS-1 molecular sieve using plasma processing technology. Background Art

[0002] As an environmentally friendly green catalytic material with excellent catalytic oxidation performance, the preparation of titanium silicalite TS-1 and its catalytic application are one of the hot topics in the field of catalytic research. Current research results have confirmed that the catalytic activity of TS-1 is strongly dependent on its crystal size. Nano TS-1 has higher catalytic activity than micron TS-1 molecular sieve. The main reason is that the nano molecular sieve has shorter pores, which is conducive to the transmission and diffusion of reactant and product molecules in the molecular sieve pore structure. The mass transfer resistance is low and side reactions are not easy to occur, so it has high selectivity. In addition, the nano molecular sieve has many exposed catalytic active sites, so it has high catalytic activity. However, there is still a lot of room for optimization in its industrial application.

[0003] For the performance optimization of molecular sieve materials, CN107311197B discloses a method for treating a composite molecular sieve material with a plasma technology to synthesize a core-shell structure, by plasma treatment of the core molecular sieve material alone, or double plasma treatment of the core molecular sieve material and the mixed solution of the core and shell molecular sieve material precursors, both generating reactive sites on the surface of the core molecular sieve material and generating free radicals in the shell molecular sieve precursor solution, accelerating the nucleation and growth of the shell molecular sieve material crystals, and forming a core-shell structure composite molecular sieve. However, the method currently has the following drawbacks: First, the method involves a multiphase treatment process and necessary subsequent separation and reprocessing links, and there are shortcomings such as cumbersome steps; secondly, the method often adjusts the properties of the prepared molecular sieve material by intervening in the crystallization process, and has strong randomness, making it difficult to controllably modify and process at the atomic level.

[0004] Plasma treatment technology is a method of modifying and treating the surface of materials using the characteristics of plasma. It is widely used in many fields, including materials science, semiconductor manufacturing, biomedicine, environmental protection, etc. However, the optimization of molecular sieve TS-1 using plasma treatment technology is still vacant. In view of the above problems, it is planned to bombard the fully crystallized finished molecular sieve with plasma jet at room temperature to directly construct silicon hydroxyl species in a controllable manner and adjust the hydrophilicity and acidity of the material. This application aims to provide a method and application of adjusting TS-1 molecular sieve using plasma treatment technology. Summary of the invention

[0005] The purpose of the present invention is to provide a method and application of adjusting TS-1 molecular sieve by plasma treatment technology, and to adjust the hydroxyl state of TS-1 molecular sieve by treating TS-1 molecular sieve based on plasma treatment technology.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] The method for adjusting TS-1 molecular sieve by plasma treatment technology comprises the following steps:

[0008] S1: TS-1 sample pretreatment;

[0009] S2: Select processing gas and preset processing conditions;

[0010] S3: Select plasma treatment equipment to lay the pretreated TS-1 sample at a certain thickness;

[0011] S4: Processing according to preset processing conditions;

[0012] S5: Post-processing and testing.

[0013] Furthermore, the TS-1 sample preprocessing of S1 includes:

[0014] The block sample was ground into powder using a mortar and dried at 80-120°C for 5-12 hours to remove impurities physically adsorbed on the surface.

[0015] Furthermore, the process gas selected in S2 and the pre-set process conditions include:

[0016] The processing gas is nitrogen (N 2 ), argon (Ar), oxygen (O 2 ), air or other mixed gases, the processing gas flow rate is 100-1000mL / min;

[0017] Power regulation: To set the power of the plasma, it is usually necessary to select an appropriate power based on the properties of the molecular sieve;

[0018] Treatment time: Determine the appropriate treatment time, which is usually between a few minutes and a few hours, depending on the purpose of the experiment;

[0019] Temperature and pressure control: If the equipment has temperature and pressure control functions, make corresponding settings to ensure that the treatment is carried out at the appropriate temperature and pressure.

[0020] Furthermore, in S3, the pretreated TS-1 powder is spread in the sample bin, and the sample thickness is adjusted to 1-6 mm, and the specific thickness is adjusted according to the property of the material.

[0021] Another object of the present invention is to disclose the application of plasma treatment technology to the method of conditioning TS-1 molecular sieve.

[0022] A modified TS-1 molecular sieve is obtained by adjusting the above plasma treatment technology.

[0023] Furthermore, the modified TS-1 molecular sieve has advantages in conversion rate and selectivity compared with the parent material in Beckmann rearrangement reaction.

[0024] Furthermore, the modified TS-1 molecular sieve loaded with metals such as copper, cobalt, and iron is used in the carbon dioxide hydrogen reduction reaction, which has a higher conversion rate and methanol selectivity than the parent.

[0025] Furthermore, the modified TS-1 molecular sieve loaded with metals such as copper, cobalt, indium, platinum, palladium and the like is used for the photocatalytic reaction of carbon dioxide and water, and has a higher conversion rate and alcohol selectivity than the parent.

[0026] The beneficial effects of the present invention are:

[0027] The present invention discloses a method and application of regulating TS-1 molecular sieve by plasma treatment technology. The modified TS-1 molecular sieve after treatment has advantages in Beckmann rearrangement reaction compared with the parent body in conversion rate and selectivity; the loaded metals such as copper, cobalt, iron, etc. are used for carbon dioxide hydrogen reduction reaction, and the conversion rate and methanol selectivity are higher than the parent body; the loaded metals such as copper, cobalt, indium, platinum, palladium, etc. are used for photo / photothermal catalytic reaction of carbon dioxide and water, and the selectivity is higher than the parent alcohol.

[0028] Meanwhile, the process of the present invention is simple, and effective processing can be completed for powdered samples without other additives, so the method is suitable for industrial application.

[0029] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of the preparation method described in an embodiment of the present invention;

[0031] Figure 2 Infrared spectra of the hydroxyl vibration region of a series of samples prepared in the examples; DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0033] The method for adjusting TS-1 molecular sieve by plasma treatment technology comprises the following steps:

[0034] S1: TS-1 sample pretreatment;

[0035] S2: Select processing gas and preset processing conditions;

[0036] S3: Select plasma treatment equipment to lay the pretreated TS-1 sample at a certain thickness;

[0037] S4: Processing according to preset processing conditions;

[0038] S5: Post-processing and testing.

[0039] The present invention will be described below in conjunction with specific embodiments:

[0040] Example 1

[0041] The TS-1 powder was treated at 90°C for 5 hours, and a mixed gas of oxygen and nitrogen (volume ratio of 1:4) was selected as the plasma treatment gas. The treatment gas flow rate was set to 300 mL / min, and the treatment power was 50, 100, 150, and 200 W, respectively. The laying thickness of the sample was 2 mm, and the treatment time was 10 min. After the treatment, the solid in the sample chamber was collected and characterized using XRD technology. Then 20 mg of solid powder was weighed for tableting, and the sample was fixed in an in-situ infrared cell equipped with a calcium fluoride window, activated at 550°C for 5 hours under vacuum conditions, and then its hydroxyl vibration zone infrared spectrum was measured.

[0042] like Figure 2 As shown, when the plasma treatment power is 100 W, the broad peak signal located at about 3500 wavenumbers in the infrared spectrum (attributed to the nested hydroxyl group) is the strongest relative to the TS-1 sample before treatment, indicating that under this condition, the number of nested hydroxyl groups prepared by plasma is the largest and the acidity is relatively stronger.

[0043] Example 2

[0044] The sample obtained by treatment at 100W power in Example 1 was applied to the Beckmann rearrangement reaction of catalyzing cyclohexanone oxime. When evaluating the reaction performance, 100mg of the catalyst was loaded into a reaction tube, activated at 350°C for 2h under a nitrogen atmosphere (flow rate of 20mL / min), and a cyclohexanone oxime / methanol solution with a mass ratio of 1:9 was introduced at 7mL / h for 1h. The generated gaseous products were collected after condensation and analyzed by a gas chromatograph, and the analysis method was the area normalization method. The catalytic performance comparison of the samples is shown in the following table:

[0045] sample Cyclohexanone oxime conversion rate (%) Caprolactam selectivity (%) Example 2 95.2 99.4 Comparison sample 69.8 89.6

[0046] Example 3

[0047] The sample obtained by treating at 100W power in Example 1 was loaded with copper element and used in catalytic carbon dioxide hydrogen reduction reaction. When evaluating the reaction performance, 200mg of the catalyst was loaded into a fixed bed, and the reaction was carried out under the conditions of carbon dioxide (flow rate of 20mL / min), hydrogen 3MPa, and 533K. The generated product was analyzed by gas chromatograph using the area normalization method. The catalytic performance comparison of the samples is shown in the following table:

[0048] sample Carbon dioxide conversion rate (%) Methanol selectivity (%) Example 3 17.5 92.6 Comparison sample 9.2 73.2

[0049] Example 4

[0050] The sample obtained by treating at 100W in Example 1 was loaded with cobalt element for the photocatalytic reaction of carbon dioxide and water. The evaluation was carried out in a reactor. First, 50mg of the catalyst was evenly dispersed in 10mL of ultrapure water, and the reactor was immediately sealed. Subsequently, the air inlet was connected to the carbon dioxide cylinder, and the air outlet was opened to allow CO2 to be purged for 15min to ensure that other gases in the kettle were completely excluded. After that, the air outlet was closed and the pressure in the kettle was accurately adjusted to 0.1MPa. The xenon lamp was turned on for illumination, and the condensation system was started synchronously, and the reaction was continued for 4h. After the reaction was completed, the product was quantitatively analyzed by gas chromatograph.

[0051] sample Ethanol selectivity (%) Methanol selectivity (%) Example 4 74.6 11.1 Comparison sample 61.2 8.9

[0052] Example 5

[0053] The sample treated at 100W in Example 1 was loaded with indium element for the photocatalytic reaction of carbon dioxide and water. The evaluation was carried out in a high-temperature and high-pressure reactor. First, 50 mg of the catalyst was evenly dispersed in 10 mL of ultrapure water, and the reactor was immediately sealed. Subsequently, the air inlet was connected to the carbon dioxide cylinder, and the air outlet was opened to allow CO2 to be purged for 15 minutes to ensure that other gases in the kettle were completely excluded. After that, the air outlet was closed and the pressure in the kettle was accurately adjusted to 0.1 MPa. Next, the xenon lamp was turned on for illumination, and the temperature control program was started synchronously. Finally, the temperature of the solution in the kettle was stably maintained at 250°C, and the reaction continued for 4 hours. After the reaction, the product was quantitatively analyzed by gas chromatograph.

[0054] sample Ethanol selectivity (%) Methanol selectivity (%) Example 5 92.8 3 Comparison sample 69.3 9.8

[0055] In the above embodiments, the control sample is an untreated matrix, or a matrix loaded with metal by the same method.

[0056] In summary, the present invention discloses a method and application of regulating TS-1 molecular sieve by plasma treatment technology. The modified TS-1 molecular sieve after treatment has advantages in Beckmann rearrangement reaction compared with the parent body in conversion rate and selectivity; the loaded metals such as copper, cobalt, and iron are used for carbon dioxide hydrogen reduction reaction, and the conversion rate and methanol selectivity are higher than the parent body; the loaded metals such as copper, cobalt, indium, platinum, palladium are used for photo / photothermal catalytic reaction of carbon dioxide and water, and the selectivity is higher than the parent alcohol.

[0057] Meanwhile, the process of the present invention is simple, and effective processing can be completed for powdered samples without other additives, so the method is suitable for industrial application.

[0058] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for regulating TS-1 molecular sieve using plasma treatment technology, characterized in that: The following steps are involved: S1: TS-1 sample pretreatment; S2: Select processing gas and preset processing conditions; S3: Select plasma treatment equipment to lay the pretreated TS-1 sample at a certain thickness; S4: Processing according to preset processing conditions; S5: Post-processing and testing.

2. The method for conditioning TS-1 molecular sieve by plasma treatment technology according to claim 1, characterized in that: The S1 TS-1 sample preprocessing includes: The block sample was ground into powder using a mortar and dried at 80-120°C for 5-12 hours to remove impurities physically adsorbed on the surface.

3. The method for conditioning TS-1 molecular sieve by plasma treatment technology according to claim 1, characterized in that: The process gas selected in S2 and the pre-set process conditions include: The processing gas is selected from nitrogen (N2), argon (Ar), oxygen (O2), air or other mixed gases, and the processing gas flow rate is 100-1000 mL / min; Power regulation: To set the power of the plasma, it is usually necessary to select an appropriate power based on the properties of the molecular sieve; Treatment time: Determine the appropriate treatment time, which is usually between a few minutes and a few hours, depending on the purpose of the experiment; Temperature and pressure control: If the equipment has temperature and pressure control functions, make corresponding settings to ensure that the treatment is carried out at the appropriate temperature and pressure.

4. The method for conditioning TS-1 molecular sieve by plasma treatment technology according to claim 3, characterized in that: A mixed gas of oxygen and nitrogen with a volume ratio of 1:4 was selected as the plasma treatment gas. The treatment gas flow rate was set to 300 mL / min, the treatment powers were set to 50, 100, 150, and 200 W, and the treatment time was set to 10 min.

5. The method for conditioning TS-1 molecular sieve by plasma treatment technology according to claim 1, characterized in that: In S3, the pretreated TS-1 powder is spread in the sample bin, and the sample thickness is adjusted to 1-6 mm. The specific thickness is adjusted according to the property of the material.

6. The method for conditioning TS-1 molecular sieve by plasma treatment technology according to claim 5, characterized in that: The laying thickness of the samples is 2 mm.

7. A modified TS-1 molecular sieve, characterized in that: The method is obtained by adjusting the mixture according to any one of claims 1 to 6.

8. A modified TS-1 molecular sieve as claimed in claim 7, characterized in that: The modified TS-1 molecular sieve has advantages in conversion rate and selectivity compared with the parent material in Beckmann rearrangement reaction.

9. A modified TS-1 molecular sieve as claimed in claim 7, characterized in that: The modified TS-1 molecular sieve loaded with metals such as copper, cobalt, and iron is used for the carbon dioxide hydrogen reduction reaction, and has a higher conversion rate and methanol selectivity than the parent.

10. A modified TS-1 molecular sieve according to claim 7, characterized in that: The modified TS-1 molecular sieve loaded with metals such as copper, cobalt, indium, platinum, palladium and the like is used for the photocatalytic reaction of carbon dioxide and water, and has a higher conversion rate and alcohol selectivity than the parent.

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