Template-free multi-level pore ETS-10 zeolite molecular sieve and its synthesis method and application

Abstract

The present invention relates to the technical field of zeolite molecular sieve synthesis, and specifically relates to a template-free hierarchical pore ETS-10 zeolite molecular sieve, its preparation method and application. The steps are as follows: Add an aqueous solution of sodium oxalate to water glass, stir evenly, then add potassium titanyl oxalate, adjust the pH to 11-12, stir evenly, and carry out hydrothermal reaction at 220-240 °C for at least 24 h. After filtering out the product, wash and dry it, and calcine it at 450 °C to obtain the product; Calculate the dosages of water glass, sodium oxalate, and potassium titanyl oxalate according to the molar ratio SiO2:TiO2:K2O:Na2O:H2O = (5.0-6.8):1.0:1.0:(4.1-6.3):(180-245); The ETS-10 zeolite molecular sieve synthesized by the present invention has a hierarchical pore structure and high crystallinity. When it is loaded with transition metals to form a catalyst and applied to the reaction of CO2 hydrogenation to methane, it has high catalytic activity and thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of zeolite molecular sieve synthesis, and in particular to a template-free multi-level pore ETS-10 zeolite molecular sieve and a synthesis method and application thereof. Background Art

[0002] Uniform pore structure, superior thermal stability, good hydrothermal stability and flexible active sites make zeolite molecular sieves widely used in the field of catalysis, such as industrial catalysis, ion exchange, adsorption separation, optics and other fields. After a lot of research, the synthesis process of microporous materials has become quite mature. At the same time, in the fine chemical process, microporous zeolite materials cannot highlight the catalytic performance of large molecules. Therefore, mesoporous zeolites with larger size structures can be used. In recent years, mesoporous zeolite materials have shown great potential in the fields of crude oil and heavy oil adsorption separation, biomass conversion, environmental energy and new assembly materials.

[0003] The most commonly used method for the multi-level pore structure of ETS-10 zeolite molecular sieve is the soft template method, which prepares the molecular sieve by assembling with aluminosilicate through non-covalent bond forces, and has obtained a relatively mature synthesis process. However, before being applied to large-scale production, due to the high synthesis cost of templates and titanium and potassium sources and the pollution to the environment, the batch application of materials has certain difficulties. Therefore, the present invention attempts to develop a high-crystallinity ETS-10 zeolite molecular sieve with a multi-level pore structure that is directly synthesized without using a template. Summary of the invention

[0004] How to synthesize high-crystallinity ETS-10 zeolite molecular sieve with multi-level pore structure without template or additive is the key technical problem to be solved by the present invention. The present invention provides a template-free multi-level pore ETS-10 zeolite molecular sieve and its preparation method and application. The synthesized ETS-10 zeolite molecular sieve has a multi-level pore structure and high crystallinity, and is used as a catalyst carrier to load a transition metal catalyst for CO 2 In the hydrogenation reaction to produce methane, it has high catalytic activity and thermal stability.

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] The preparation method of template-free multi-level pore ETS-10 zeolite molecular sieve comprises the following steps:

[0007] The sodium oxalate aqueous solution is added to water glass, and after stirring evenly, potassium titanium oxalate solid is added, the pH is adjusted to between 11 and 12, and after stirring evenly, a hydrothermal reaction is carried out at 220-240° C. for at least 24 hours, the product is filtered out, washed, and dried, and then the product is calcined at 450° C. to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve;

[0008] According to the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=(5.0-6.8):1.0:1.0:(4.1-6.3):(180-245) Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and feed them, among which Na 2 The molar number of O is the sum of the sodium elements contained in water glass and sodium oxalate.

[0009] Further, according to the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=(5.0-6.8):1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0010] Further, according to the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:(4.1-6.3):205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0011] Further, according to the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:(180-245) Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0012] Furthermore, the temperature of the hydrothermal reaction is 230° C. and the reaction time is 72 h; and the calcination time is 6 h.

[0013] The second aspect of the present invention provides a template-free multi-level pore ETS-10 zeolite molecular sieve obtained by the above preparation method.

[0014] The third aspect of the present invention provides a template-free multi-level pore ETS-10 zeolite molecular sieve obtained by the above preparation method in CO 2 The application in the hydrogenation to methane reaction is specifically to load the template-free multi-level pore ETS-10 zeolite molecular sieve with transition metal to prepare a catalyst for use.

[0015] Furthermore, the transition metal is one or more of Zr, Ni, Co, Zn, Cu, Fe, Ce, and Mn, and preferably the transition metal is a metal containing Ni.

[0016] Beneficial technical effects:

[0017] The present invention uses potassium titanium oxalate as a titanium source and a potassium source, sodium oxalate as a sodium source, and does not use a template agent. The high crystallinity ETS-10 zeolite molecular sieve with a multi-level pore structure is directly synthesized by hydrothermal crystallization. On the one hand, during the synthesis process, the C 2 O 4 2- The radical decomposes into CO 2 The gas is discharged, thus forming a mesoporous structure inside it; on the other hand, potassium titanium oxalate also replaces traditional potassium salts to play the role of an inorganic structure directing agent;

[0018] Compared with the prior art, the present invention does not require the use of additional template agents and potassium sources, greatly reducing the dependence on mesoporous organic template agents in traditional synthesis methods, and finding a simple and inexpensive synthesis route; the method of the present invention is simple, safe, low-cost, and green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The XRD patterns of the hierarchical pore ETS-10 zeolite molecular sieves synthesized with different silicon-titanium ratios in Examples 1-4; wherein a represents the molar ratio of SiO 2 :TiO 2 =5.0, b represents the molar ratio of SiO in Example 2 2 :TiO 2 =5.6, c represents the molar ratio of SiO in Example 3 2 :TiO 2 =6.2, d represents the molar ratio of SiO in Example 4 2 :TiO 2 =6.8;

[0020] Figure 2 The XRD patterns of the multi-level pore ETS-10 zeolite molecular sieves synthesized in Examples 3 and 5-9 with different sodium oxalate addition amounts; wherein a represents Example 5 (sodium oxalate is replaced by sodium chloride), and b represents the molar ratio of Na 2 O:TiO 2 =4.1, c represents the molar ratio of Na in Example 7 2 O:TiO 2 =4.7, d represents the molar ratio of Na in Example 3 2 O:TiO 2 =5.2, e represents the molar ratio of Na in Example 8 2 O:TiO2 =5.6, f represents the molar ratio of Na in Example 9 2 O:TiO 2 =6.3;

[0021] Figure 3 XRD patterns of hierarchical pore ETS-10 zeolite molecular sieves synthesized in different addition orders and potassium titanium oxalate addition methods in Examples 3, 10-11; wherein a represents Example 3 (raw material order: water glass → sodium oxalate → potassium titanium oxalate solid), b represents Example 10 (raw material order: water glass → potassium titanium oxalate solid → sodium oxalate), and c represents Example 11 (raw material order: water glass → potassium titanium oxalate solution → sodium oxalate);

[0022] Figure 4 The XRD patterns of the hierarchical pore ETS-10 zeolite molecular sieve synthesized at different water-titanium ratios in Examples 3 and 12-15; wherein a represents the molar ratio H of Example 12. 2 O:TiO 2 =180, b represents the molar ratio H of Example 13 2 O:TiO 2 =195, c represents the molar ratio H of Example 3 2 O:TiO 2 =205, d represents the molar ratio H of Example 14 2 O:TiO 2 =225, e represents the molar ratio H of Example 15 2 O:TiO 2 =245;

[0023] Figure 5 The activity diagram of the catalyst prepared by loading different metals with the template-free multi-level pore ETS-10 zeolite molecular sieve obtained in Example 3;

[0024] Figure 6 The adsorption isotherm and pore distribution curve of the template-free multi-level pore ETS-10 zeolite molecular sieve obtained in Example 3;

[0025] Figure 7 This is a SEM scanning electron microscope image of the template-free multi-level pore ETS-10 zeolite molecular sieve obtained in Example 3. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0027] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0028] The experimental methods in the following examples without specific conditions are usually measured according to national standards; if there is no corresponding national standard, it is carried out according to the general international standards or the standard requirements proposed by relevant enterprises.

[0029] The molar ratio of each material in the following examples and comparative examples is SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O”, SiO 2 The molar number of TiO is calculated according to the molar number of silicon in water glass; 2 The molar number of K is calculated based on the molar number of titanium in potassium titanium oxalate; 2 The molar number of O is calculated based on the molar number of potassium in potassium titanium oxalate; Na 2 The molar number of O is calculated based on the total molar number of sodium in water glass and sodium oxalate in the whole system; H 2 The molar number of O is the sum of the water contained in the entire system from the sodium oxalate aqueous solution, water glass and other solutions.

[0030] The water glass composition in the following examples is as follows: SiO 2 6.865 mol / L, Na 2 O 1.8444 mol / L, H 2 O49.8333mol / L.

[0031] Test and calculation method of crystallinity (%): The crystallinity was tested using an X-ray diffractometer, and the calculation formula was: crystallinity = (diffraction peak intensity / total intensity) × 100%, and jade software was used for data processing.

[0032] SBET was measured by nitrogen adsorption using a physical adsorption instrument.

[0033] Conversion rate = (amount of initial reaction substance (mol) - amount of unconverted substance (mol)) / amount of initial reaction substance (mol) × 100%;

[0034] Yield = amount of target product (mol) / amount of initial reaction material (mol) × 100%.

[0035] Example 1

[0036] 22.2 mL of water was added dropwise to 10.3 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, a hydrothermal reaction was carried out at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0037] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=5.0:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0038] Example 2

[0039] 20.9 mL of water was added dropwise to 11.5 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0040] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2O=5.6:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0041] Example 3

[0042] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0043] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0044] Example 4

[0045] 18.9 mL of water was added dropwise to 13.9 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0046] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.8:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0047] Experimental Examples 1-4 are designed to compare the effects of different silicon-titanium ratio systems. The ETS-10 zeolite prepared in Examples 1-4 was subjected to XRD testing. The obtained XRD patterns are shown in Figure 1 When the silicon-titanium molar ratio is 5.0-5.6, a large amount of rutile and anatase TiO 2The crystalline phase and the lack of complete ETS1-10 characteristic peaks are attributed to the fact that the silicon species content in the system is insufficient to combine with the quantitative titanium species in the system to form titanosilicates, resulting in the conversion of titanium species into a series of TiO 2 When the silicon-titanium molar ratio is 6.8, the sample has poor crystallinity, and the XRD spectrum shows a typical quartz phase peak at 2θ=27°, which is attributed to the polymerization of excess silicon species in the system to form SiO 2 Therefore, the silicon-titanium molar ratio of 6.2 in Example 3 is selected as the best ratio.

[0048] Example 5

[0049] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium chloride solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, an appropriate amount of hydrochloric acid solution was added to adjust the pH to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0050] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0051] Example 6

[0052] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 1.85 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0053] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:4.1:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0054] Example 7

[0055] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.37 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0056] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:4.7:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0057] Example 8

[0058] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 3.14 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0059] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.6:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0060] Example 9

[0061] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 3.74 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0062] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K2 O:Na 2 O:H 2 O=6.2:1.0:1.0:6.3:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0063] The purpose of the configuration of Examples 3 and 5-9 is to compare the effects of different amounts of sodium oxalate on the system. The ETS-10 zeolite prepared in Examples 5-9 was subjected to XRD testing and BET characterization. The obtained XRD patterns are shown in Figure 2 In Example 5, sodium chloride was used as the sodium source, and only microporous ETS-10 could be synthesized. In Examples 6-7, as the amount of sodium oxalate increased, mesoporous zeolites gradually appeared, which was attributed to the fact that the amount of sodium oxalate would affect the C 2 O 4 2- The concentration of C 2 O 4 2- The concentration of C 2 O 4 2- It is easy to decompose and produce CO at higher hydrothermal synthesis temperature 2 , resulting in the synthesized sample having a hollow structure, while creating some cracks on the zeolite particles, promoting the formation of mesopores. When the sodium-titanium molar ratio is 5.2 (Example 3), the sample has a larger mesopore volume and higher crystallinity. In Examples 8-9, with the increase of C 2 O 4 2- As the concentration of C increases further, the crystallinity and relative intensity of each diffraction peak decrease, which may be due to the excessive C 2 O 4 2- The anions have a strong complexation with the titanium species, which hinders the aggregation of the titanium species and the silicate anions. Therefore, the sodium-titanium molar ratio of 5.2 in Example 3 is selected as the best ratio.

[0064] Example 10

[0065] 20 mL of water was added dropwise to 12.7 mL of water glass, followed by the addition of 4.2 g of potassium titanium oxalate. After the solid was completely dissolved, it was stirred for 2 h, followed by the addition of 14.6 mL of 2.80 mol / L sodium oxalate solution, and the pH was adjusted to about 11.6. After stirring for 30 min, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0066] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0067] Embodiment 11

[0068] 20 mL of 0.62 mol / L potassium titanium oxalate solution was added dropwise into 12.7 mL of water glass and stirred for 2 h. Subsequently, 14.6 mL of 2.80 mol / L sodium oxalate solution was added and the pH was adjusted to about 11.6. After stirring for 30 min, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0069] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:205 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0070] The purpose of setting up Examples 3 and 10-11 is to compare the effects of different addition orders and addition methods of potassium titanium oxalate on the system. In Example 10, potassium titanium oxalate solid is added first. Since water glass itself has viscosity, potassium titanium oxalate solid is not easy to dissolve, which easily leads to poor fluidity of the mother liquor. In Example 11, potassium titanium oxalate is added in the form of a solution, and the crystallinity of the obtained product is slightly lower than that of the addition method in Experimental Example 3.

[0071] Example 12

[0072] 14.5 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0073] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:180 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0074] Embodiment 13

[0075] 17.8 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0076] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:195 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0077] Embodiment 14

[0078] 24.5 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0079] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:225 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0080] Embodiment 15

[0081] 29.0 mL of water was added dropwise to 12.7 mL of water glass, followed by 14.6 mL of 2.80 mol / L sodium oxalate solution. After stirring for 30 min, 4.2 g of potassium titanium oxalate was added. After the solid was completely dissolved, the pH was adjusted to about 11.6. After stirring for 2 h, the mixture was hydrothermally reacted at 230 °C for 72 h. The product was taken out, washed, dried, and calcined at 450 °C for 6 h to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve. The texture properties of the product are shown in Table 1.

[0082] In this embodiment, the molar ratio of SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O=6.2:1.0:1.0:5.2:245 Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate and add the materials.

[0083] Experimental Example 3 and Examples 12-15 are designed to compare the effects of different water-titanium molar ratios on the system. The ETS-10 zeolite prepared in Examples 3 and 10-13 was subjected to XRD testing. The obtained XRD patterns are shown in Figure 4 When the water-titanium molar ratio is between 180-195, TiO 2 The appearance of the impurity peaks of the quartz phase is attributed to the increase of the system viscosity, which leads to the uneven mixing of the inorganic species in the system, thus inducing the formation of impurities. When the water-titanium molar ratio is between 225-245, the crystallinity gradually decreases, which is attributed to the increase of water content leading to the decrease of the system viscosity, thereby reducing the intermolecular force, which is not conducive to the formation of the ETS-10 zeolite molecular sieve framework.

[0084] Comparative Example 1

[0085] Preparation of Traditional Microporous ETS-10 Zeolite Molecular Sieve

[0086] 1.8 g potassium fluoride dissolved in 5 mL H 2 O to form solution A; dissolve 1.45g of sodium hydroxide in 10mL of water, add dropwise to 9.2mL of water glass, stir for 10min, then add dropwise 5.9g of TiCl 3 After stirring for 60 minutes, solution A was added dropwise; after stirring for 2 hours, it was placed in a hydrothermal reactor, sealed, and crystallized in an oven at 230°C for 72 hours. The molar ratio of each material in the system is SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O = 7.0: 1.0: 1.9: 4.0: 163. The texture properties of the prepared microporous ETS-10 are shown in Table 1.

[0087] Comparative Example 2

[0088] Preparation of traditional multi-level pore ETS-10 zeolite molecular sieve

[0089] Multi-level pore ETS-10 was synthesized using N,N-diethyl-N-hexadecyl-N-(3-methoxysilylpropane) ammonium iodide (DMMC) as a soft template. The preparation method was as follows: 1.8 g potassium fluoride was dissolved in 5 mL H 2O to form solution A; dissolve 1.45g of sodium hydroxide in 10mL of water, add dropwise to 9.2mL of water glass, stir for 10min, then add dropwise 5.9g of TiCl 3 After stirring for 60 minutes, solution A was added dropwise; after stirring for 2 hours, 2.5 mL of DMMC was added. Then, the mixture was placed in a hydrothermal reactor, sealed, and crystallized in an oven at 230°C for 72 hours. The molar ratio of each material in the system is SiO 2 :TiO 2 :K 2 O:Na 2 O:H 2 O = 7.0: 1.0: 1.9: 4.0: 163. The texture properties of the obtained multi-level pore ETS-10 are shown in Table 1.

[0090] Comparative Example 3

[0091] Preparation of ETS-10 zeolite molecular sieve using sodium lignosulfonate as additive

[0092] After 2 g of 1-ethyl-3-methylimidazolium chloride was fully mixed with 50 mL of 1 mol / L NaOH solution, it was stirred at room temperature for 2 h, and then 2 g of sodium lignin sulfonate was added and continued to be stirred. After being placed in an oven at 80°C for 12 h, the mixed solution was taken out and washed with water until the pH was neutral (referred to as IL-LnNa).

[0093] Take 16 mL of water glass and stir at room temperature for 10 min, then mix thoroughly with 2 mL of the above mixed solution. After stirring for 1 h, add 20 mL of H 2 O and continue stirring for 20 minutes, then add 6.9g NaCl and 2.8g KF successively and stir for 1h respectively, finally add 1.3g P25, stir for 2h, put into the hydrothermal reactor, seal it, and stand in an oven at 230℃ for crystallization for 60 hours. The molar ratio of each material in the system is Na 2 O:K 2 O:TiO 2 :SiO 2 IL-LnNa:H 2 O = 3.5: 1.6: 1.0: 5.5: 0.043: 181. The texture properties of the obtained multi-level pore ETS-10 are shown in Table 1.

[0094] Table 1 Preparation parameters and texture properties of the products of the above examples and comparative examples

[0095]

[0096]

[0097] Application Example 1

[0098] The template-free multi-level pore ETS-10 zeolite molecular sieve prepared in Example 3 was applied to CO 2 In the hydrogenation reaction to produce methane. The ETS-10 zeolite molecular sieve is used as a carrier to load a transition metal catalyst. The specific preparation process is as follows: the ETS-10 zeolite molecular sieve sample of Example 3 is used as a catalyst carrier, and it is immersed in a solution containing a metal precursor so that the final transition metal loading is 5wt% of the carrier weight, wherein the metal precursor is a nitrate; the impregnated sample is placed in the air and dried at room temperature overnight, then placed in an oven at 110°C and finally calcined at 450°C for 4h to obtain a nickel-loaded zeolite molecular sieve catalyst. The catalyst needs to be reduced before use: a certain amount of the catalyst is sieved to the target mesh size, and then reduced at 400°C for 4h in a hydrogen atmosphere.

[0099] CO 2 Hydrogenation to methane reaction: The reaction was carried out in a 250 mL autoclave. 0.2 g of the above-prepared catalyst powder and 10 mL of 1,4-dioxane were weighed and added to the 250 mL autoclave. H 2 :N 2 :CO 2 =4:1:1 mixed gas three times to remove excess air in the kettle, and then fill with 3MPa mixed gas. The reaction conditions are: reaction temperature 200℃, reaction time 3h, stirring speed during the reaction is 600rpm. After the reaction is completed, the product is collected, the pressure is released, and the product is quantified using gas chromatography.

[0100] According to the above method, a series of catalysts of 5% Co / ETS-10, 5% Zr / ETS-10, 5% Cu / ETS-10, 5% Ni / ETS-10, 5% Fe / ETS-10, 5% Ce / ETS-10, and 5% Mn / ETS-10 were prepared using the zeolite molecular sieve of Example 3 as a carrier for testing. Nickel-based catalysts were prepared using Comparative Examples 1-3 and ZSM-5, SPAO-56, BETA, X, and Y zeolites according to the same impregnation method. The catalytic activity results are shown in Table 1. Figure 5 and Table 2.

[0101] Table 2 Effect of different catalysts on CO 2 Comparison of the activity of hydrogenation to methane

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[0103]

[0104] From Table 2 and Figure 5 It can be seen that the multi-level pore ETS-10 prepared by the present invention has good performance in catalyzing CO 2The conversion rate in the hydrogenation to methane reaction can reach 41.8%, and the methane selectivity can reach 100%, which are higher than the performance of the catalyst prepared using each comparative example as a carrier.

[0105] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a template-free multi-level pore ETS-10 zeolite molecular sieve, characterized in that: The steps include: The sodium oxalate aqueous solution is added to water glass, and after stirring evenly, potassium titanium oxalate solid is added, the pH is adjusted to between 11 and 12, and after stirring evenly, a hydrothermal reaction is carried out at 220-240° C. for at least 24 hours, the product is filtered out, washed, and dried, and then the product is calcined at 450° C. to obtain a template-free multi-level pore ETS-10 zeolite molecular sieve; The amounts of water glass, sodium oxalate and potassium titanium oxalate are calculated and added according to the molar ratio of SiO2:TiO2:K2O:Na2O:H2O=(5.0-6.8):1.0:1.0:(4.1-6.3):(180-245), wherein the molar number of Na2O is the sum of the sodium elements contained in water glass and sodium oxalate.

2. The method for preparing the template-free multi-level pore ETS-10 zeolite molecular sieve according to claim 1, characterized in that: Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate according to the molar ratio of SiO2:TiO2:K2O:Na2O:H2O=(5.0-6.8):1.0:1.0:5.2:205 and add the materials.

3. The method for preparing the template-free multi-level pore ETS-10 zeolite molecular sieve according to claim 1, characterized in that: Calculate the amount of water glass, sodium oxalate and potassium titanium oxalate according to the molar ratio of SiO2:TiO2:K2O:Na2O:H2O=6.2:1.0:1.0:(4.1-6.3):205 and add the materials.

4. The method for preparing the template-free multi-level pore ETS-10 zeolite molecular sieve according to claim 1, characterized in that: According to the molar ratio of SiO2:TiO2:K2O:Na2O:H2O=6.2:1.0:1.0:5.2:(180-245), the amount of water glass, sodium oxalate and potassium titanium oxalate were calculated and added.

5. The method for preparing the template-free multi-level pore ETS-10 zeolite molecular sieve according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 230° C. and the reaction time is 72 h; the calcination time is 6 h.

6. The template-free multi-level pore ETS-10 zeolite molecular sieve obtained according to the preparation method according to any one of claims 1 to 5.

7. Application of the template-free multi-level pore ETS-10 zeolite molecular sieve obtained by the preparation method according to any one of claims 1 to 5 in the CO2 hydrogenation to methane reaction, characterized in that: The multi-level pore ETS-10 zeolite molecular sieve is loaded with transition metal to prepare a catalyst for use.

8. The use according to claim 7, characterized in that: The transition metal is one or more of Zr, Ni, Co, Zn, Cu, Fe, Ce, and Mn.

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