Silicon dioxide hybrid membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of membrane material separation, and discloses a silicon dioxide hybrid membrane as well as a preparation method and application thereof. The invention discloses a silicon dioxide hybrid membrane. The hybrid membrane comprises a porous support body, a transition layer and a separation layer, the transition layer comprises silicon zirconium oxide; the separation layer comprises a silicon oxide, a metal R and a metal M, the metal R is selected from lanthanide series metal elements, and the metal M is selected from at least one of VIII group metal elements, IIA group metal elements and IIIA group metal elements. The silicon dioxide hybrid membrane disclosed by the invention is applied to hydrogen separation and purification and has relatively high hydrogen selectivity.

Description

Technical Field

[0001] The invention relates to the technical field of membrane material separation, and in particular to a silicon dioxide hybrid membrane and a preparation method and application thereof. Background Art

[0002] Hydrogen is a clean, efficient and sustainable energy source. According to the International Energy Agency, the global industrial demand for hydrogen energy is expected to increase by 44% by 2030. Existing industrial hydrogen production methods include water splitting, methane reforming, ammonia decomposition, etc. In these processes, the final product of H2 is always mixed with N2, CO2 and other gases, which is required for high-purity separation. Membranes are an attractive technology for separating H2 mixtures and have been widely studied due to their low energy consumption without any phase change. The sol-gel method can control the pore size and obtain a relatively thin (less than 100nm) separation layer, which is required to achieve high permeability. However, the main problems of pure silica membranes include poor gas permeability and selectivity, and insufficient hydrothermal stability when exposed to water vapor environments. The increase in selectivity is usually at the expense of reduced membrane permeability. In general, it is difficult for a single membrane material to overcome the contradiction between permeability and selectivity, so the membrane needs to be modified. Modification of silica with a single metal is still limited in improving hydrogen separation performance. Therefore, how to further improve the permeability and selectivity of the separation membrane through other modifications is the direction currently being tackled by technicians in this field. Summary of the invention

[0003] The purpose of the present invention is to overcome the problem that the hydrogen selectivity in gas separation of existing inorganic membranes needs to be further improved, and to provide a silicon dioxide hybrid membrane and its preparation method and application. The silicon dioxide hybrid membrane of the present invention is applied to hydrogen separation and purification, and has high hydrogen selectivity.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a silica hybrid membrane on the one hand, which comprises a porous support, a transition layer and a separation layer; the transition layer comprises silicon zirconium oxide; the separation layer comprises silicon oxide, metal R and metal M, the metal R is selected from lanthanide metal elements, and the metal M is selected from at least one of the metal elements of Group VIII, Group IIA and Group IIIA.

[0005] Preferably, in the separation layer, the metal R exists in the form of Si-OR covalent bonds, and the metal M exists in the form of oxides.

[0006] Preferably, the average pore size of the porous support is 0.1-1 μm.

[0007] Preferably, the average pore size of the transition layer is 2-10 nm.

[0008] Preferably, the average pore size of the separation layer is less than 2 nm, preferably 0.5-1.5 nm.

[0009] Preferably, calculated on an element basis, the mass ratio of metal R to metal M is 1:1-15, preferably 1:2-8.

[0010] A second aspect of the present invention provides a method for preparing a silicon dioxide hybrid film, the method comprising:

[0011] (1) in the presence of a first solvent, subjecting an inorganic silica sol, a metal R compound and a metal M compound to a first reaction to obtain a bimetallic / inorganic silica sol, wherein the metal R is selected from a lanthanide metal element, and the metal M is selected from at least one of a group VIII, group IIA and group IIIA metal element;

[0012] (2) coating the silicon zirconium sol onto a porous support, and then performing a first calcination to obtain a transition layer;

[0013] (3) coating the bimetallic / inorganic silica sol obtained in step (1) on the transition layer, and then performing a second calcination to obtain a separation layer.

[0014] The third aspect of the present invention provides an application of the silica hybrid membrane described in the first aspect or the silica hybrid membrane prepared by the preparation method described in the second aspect in gas separation and purification, preferably in hydrogen separation and purification.

[0015] Through the above technical solution, the beneficial effects of the present invention include:

[0016] The silica hybrid membrane provided by the present invention adopts a specific type of bimetallic synergy. Preferably, the metal R exists in the form of Si-OR bonds in the silica network, and the metal M exists in the form of oxides (nanoparticles) in the separation layer, which is beneficial to improving the adsorption of hydrogen by the separation membrane and improving the selectivity of hydrogen, thereby significantly improving the H2 separation effect of the membrane. The silica hybrid membrane of the present invention is applied to hydrogen separation and purification, and has a high hydrogen selectivity. The hybrid membrane of the present invention can effectively solve the problem of efficient separation of H2 / N2 and H2 / C3H8 in industrial gases (H2, CO2, O2, N2, CH4, CO, C3H8). BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is the XRD diagram of the xerogels prepared in Example 1 and Comparative Examples 1-3;

[0018] Figure 2 It is the XPS graph of the dry gels prepared in Example 1 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] On the one hand, the present invention provides a silicon dioxide hybrid membrane, which includes a porous support, a transition layer and a separation layer; the transition layer includes silicon zirconium oxide; the separation layer includes silicon oxide, metal R and metal M, the metal R is selected from lanthanide metal elements, and the metal M is selected from at least one of Group VIII, Group IIA and Group IIIA metal elements.

[0021] According to the present invention, preferably, in the separation layer, the metal R exists in the form of Si-OR covalent bonds, and the metal M exists in the form of oxides. This preferred embodiment is conducive to further improving the membrane's adsorption of hydrogen and improving hydrogen selectivity.

[0022] The existence forms of the metal R and the metal M described in the present invention are measured by XPS and XRD, respectively.

[0023] According to the present invention, preferably, the average pore size of the porous support is 0.1-1 μm, for example, it can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm and any value in the range formed by any two of these point values.

[0024] According to the present invention, preferably, the average pore size of the transition layer is 2-10 nm, for example, it can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm and any value in the range formed by any two of these point values.

[0025] According to the present invention, preferably, the average pore size of the separation layer is less than 2 nm, preferably 0.5-1.5 nm, for example, it can be 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 1.1 nm, 1.2 nm, 1.5 nm and any value in the range formed by any two of these point values.

[0026] Controlling the average pore size of the porous support, transition layer, and separation layer within the above range is beneficial to improving the adsorption of hydrogen by the obtained silica hybrid membrane, and is beneficial to improving the selectivity of hydrogen, thereby significantly improving the H2 separation effect of the membrane.

[0027] The average pore diameters of the porous support, transition layer and separation layer of the present invention are measured by the BET method.

[0028] The metal R of the present invention can be various lanthanide metal elements commonly used in the art. Preferably, the metal R is selected from at least one of lanthanum, cerium and neodymium, preferably lanthanum.

[0029] According to the present invention, preferably, the metal M is selected from at least one of cobalt, nickel, magnesium and aluminum, preferably nickel.

[0030] The inventors have found that the use of the above-mentioned specific types of metal coordination is beneficial to improving the selectivity of H2 / N2 and H2 / C3H8.

[0031] According to the present invention, preferably, in the separation layer, the ratio of the mass of silicon oxide calculated as silicon element to the total mass of metal calculated as element is 1-5:1, preferably 1.5-4:1. This preferred embodiment is more conducive to improving the permeability of H2 and the selectivity of hydrogen.

[0032] According to the present invention, preferably, the mass ratio of metal R to metal M is 1:1-15, preferably 1:2-8, calculated as elements. This preferred embodiment is more conducive to improving the permeability of H2 and the selectivity of hydrogen. When it is lower than this range, the permeability of H2 decreases; when it is higher than this range, the selectivity of hydrogen decreases.

[0033] The content of each component in the present invention is calculated by feeding amount.

[0034] The present invention has no particular limitation on the molar ratio of silicon to zirconium in the silicon zirconium oxide, provided that the average pore size of the transition layer obtained is within the range of 2-10 nm. Preferably, in the silicon zirconium oxide, the molar ratio of silicon to zirconium is 0.5-10, for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 and any value in the range formed by any two of these point values.

[0035] The porous support of the present invention has a wide range of choices. Preferably, the porous support of the present invention can be selected from at least one of porous ceramics, porous glass, porous metal (such as porous stainless steel), porous quartz and high molecular polymer, more preferably porous ceramics.

[0036] The type of porous ceramics of the present invention can be a conventional choice in the art, for example, it can be selected from one or more of Al2O3, SiO2, BaSO4, BaO, TiO2, CuO, MgO, Mg(OH)2, LiAlO2, ZrO2, CNT, BN, SiC, Si3N4, WC, BC, AlN, Fe2O3, BaTiO3, MoS2, V2O5, PbTiO3, TiB2, CaSiO3, molecular sieves, clay, boehmite and kaolin. In order to improve the separation performance of the separation membrane and based on cost considerations, preferably, the porous support is alumina, preferably α-Al2O3.

[0037] The present invention has no particular limitation on the source of the porous support, which can be obtained from commercial sources or prepared by conventional methods, as long as the above-mentioned pore size requirements are met.

[0038] The present invention has no particular limitation on the method for preparing the above-mentioned silica hybrid membrane, as long as the silica hybrid membrane with the above-mentioned characteristics can be prepared. In order to further improve the separation performance of the silica hybrid membrane, the present invention also provides a method for preparing the above-mentioned silica hybrid membrane.

[0039] A second aspect of the present invention provides a method for preparing a silicon dioxide hybrid film, the method comprising:

[0040] (1) in the presence of a first solvent, subjecting an inorganic silica sol, a metal R compound and a metal M compound to a first reaction to obtain a bimetallic / inorganic silica sol, wherein the metal R is selected from a lanthanide metal element, and the metal M is selected from at least one of a group VIII, group IIA and group IIIA metal element;

[0041] (2) coating the silicon zirconium sol onto a porous support, and then performing a first calcination to obtain a transition layer;

[0042] (3) coating the bimetallic / inorganic silica sol obtained in step (1) on the transition layer, and then performing a second calcination to obtain a separation layer.

[0043] According to the present invention, preferably, the average pore size of the porous support is 0.1-1 μm.

[0044] According to the present invention, preferably, the average pore size of the transition layer is 2-10 nm.

[0045] According to the present invention, preferably, the average pore size of the separation layer is less than 2 nm, preferably 0.5-1.5 nm.

[0046] According to the present invention, preferably, the conditions of the first reaction in step (1) include: temperature of 45-65° C. and time of 1-5 h.

[0047] According to a preferred embodiment of the present invention, the process of step (1) comprises: firstly dissolving the metal R compound and the metal M compound in a first solvent, and then adding them to the inorganic silica sol obtained in step (1) to react.

[0048] According to a specific embodiment of the present invention, the metal R compound and the metal M compound are first dissolved in a first solvent, and then added dropwise to the inorganic silica sol obtained in step (1) for reflux reaction.

[0049] According to the present invention, preferably, the ratio of the mass of the inorganic silica sol calculated as silicon element to the total mass of the metal compound calculated as metal element is 1-5:1, preferably 1.5-4:1.

[0050] According to the present invention, preferably, calculated on the basis of metal elements, the mass ratio of the metal R compound to the metal M compound is 1:1-15, preferably 1:2-8.

[0051] The metal R of the present invention can be various lanthanide metal elements commonly used in the art. Preferably, the metal R is selected from at least one of lanthanum, cerium and neodymium, preferably lanthanum.

[0052] According to the present invention, preferably, the metal M is selected from at least one of cobalt, nickel, magnesium and aluminum, preferably nickel.

[0053] The present invention has no particular limitation on the types of the metal R compound and the metal M compound, and they can be conventionally selected in the art, as long as they contain the above-mentioned metal R and metal M. Preferably, the metal R compound and the metal M compound are each independently selected from at least one of nitrates, sulfates and hydrochlorides. For example, cobalt chloride, nickel chloride, aluminum chloride, lanthanum chloride, cobalt nitrate, nickel nitrate, aluminum nitrate, lanthanum nitrate, cobalt sulfate, nickel sulfate, aluminum sulfate, lanthanum sulfate, etc.

[0054] The present invention has a wide range of choices for the first solvent, and any solvent that is compatible with and non-reactive with the substance added in step (1) can be used. In the present invention, ethanol is preferably used.

[0055] Preferably, the molar ratio of the first solvent to the metal compound calculated as the metal element is 20-70:1.

[0056] The present invention has no particular limitation on the source of the inorganic silica sol, which can be purchased commercially or prepared by conventional methods in the art. The present invention preferably prepares the inorganic silica sol by hydrolyzing a silicon source under acid catalysis.

[0057] Preferably, the method for preparing the inorganic silica sol comprises: subjecting a silicon source, water, an acid and a second solvent to a second reaction.

[0058] Preferably, the conditions of the second reaction include: temperature of 40-65° C. and time of 2-8 h.

[0059] Preferably, the second reaction is carried out under reflux conditions.

[0060] According to a specific embodiment of the present invention, the silicon source is first dissolved in the second solvent, and then a mixed solution of acid and water is added dropwise to perform a reflux reaction.

[0061] Preferably, the molar ratio of silicon source, H2O and acid is 1:20-30:0.05-0.2. The acid catalysis system with low water-silicon ratio is conducive to the growth and interconnection of polymer silicon chains, thereby forming a structure with a high proportion of uncondensed silanol bonds (Si-OH).

[0062] Preferably, the acid is an inorganic acid, preferably at least one selected from nitric acid, sulfuric acid and hydrochloric acid.

[0063] The present invention has a wide range of selection for the type of the silicon source. Preferably, the silicon source is selected from at least one of ethyl orthosilicate, methyl orthosilicate, tetraethyl silicate and ethyl methyl silicate.

[0064] The present invention has a wide range of choices for the second solvent, and any solvent that is compatible with and non-reactive with the above-mentioned added substances can be used. In the present invention, ethanol is preferably used.

[0065] Preferably, the molar ratio of the silicon source to the second solvent is 1:3-15, calculated as silicon element.

[0066] The present invention has no particular limitation on the coating method used in the preparation of the transition layer in step (2), and the coating method can be carried out using conventional methods in the art.

[0067] In order to optimize the coating effect, the present invention preferably adopts a small amount and multiple times method for coating.

[0068] There is no particular limitation on the number of coating times in the process of forming the transition layer of the present invention, and there is no particular limitation on the amount of silica zirconium sol used in the coating process, as long as the average pore size of the obtained transition layer is within the range of 2-10 nm.

[0069] According to a specific embodiment of the present invention, the preparation process of the transition layer in step (2) includes: coating the silicon zirconium sol on the porous support, then performing a first calcination, and repeating the coating-first calcination process to obtain the transition layer.

[0070] According to the present invention, preferably, the silicon-zirconium molar ratio of the silicon-zirconium sol is 0.5-10.

[0071] According to the present invention, preferably, the concentration of the silica zirconium sol is 0.5-10 wt %.

[0072] The present invention has no particular limitation on the source of the silica zirconium sol, which can be obtained from commercial sources or prepared by conventional methods, as long as the above characteristic parameters are met.

[0073] The porous support of the present invention has a wide range of choices. Preferably, the porous support of the present invention can be selected from at least one of porous ceramics, porous glass, porous metal (such as porous stainless steel), porous quartz and high molecular polymer, more preferably porous ceramics.

[0074] The type of porous ceramics of the present invention can be a conventional choice in the art, for example, it can be selected from one or more of Al2O3, SiO2, BaSO4, BaO, TiO2, CuO, MgO, Mg(OH)2, LiAlO2, ZrO2, CNT, BN, SiC, Si3N4, WC, BC, AlN, Fe2O3, BaTiO3, MoS2, α-V2O5, PbTiO3, TiB2, CaSiO3, molecular sieves, clay, boehmite and kaolin. In order to improve the separation performance of the separation membrane and based on cost considerations, preferably, the porous support is alumina, preferably α-Al2O3.

[0075] The present invention has no particular limitation on the shape of the porous support, and it can be any common shape, such as a tube, a sheet, a hollow fiber, etc.

[0076] According to the present invention, preferably, the conditions of the first calcination in step (2) and the second calcination in step (3) each independently include: a temperature of 500-600° C. and a time of 20-60 minutes.

[0077] The present invention has no particular limitation on the coating method used in the process of preparing the separation layer in step (3), and the coating method can be carried out using conventional methods in the art.

[0078] In order to optimize the coating effect, the present invention preferably adopts a small amount and multiple times method for coating.

[0079] There is no particular limit on the number of coating times in the separation layer formation process of the present invention, and there is no particular limit on the amount of bimetallic / inorganic silica sol used in the coating process, as long as the average pore size of the separation layer obtained is less than 10 nm.

[0080] According to a specific embodiment of the present invention, the preparation process of the separation layer in step (3) includes: coating the bimetallic / inorganic silica sol obtained in step (1) on the transition layer, then performing a second calcination, and repeating the coating-second calcination process to obtain the separation layer.

[0081] According to the present invention, preferably, the method further comprises: before coating the silica zirconium sol onto the porous support, calcining the porous support. This preferred embodiment is conducive to removing impurities on the surface of the porous support and activating the porous support.

[0082] According to the present invention, preferably, the calcination treatment conditions include: a temperature of 500-600° C. and a time of 0.5-10 h.

[0083] When the surface of the porous support is smooth, the porous support can be calcined without polishing.

[0084] When the surface of the porous support is rough, preferably, the method further comprises: first grinding the porous support and then calcining the porous support. This preferred embodiment is conducive to obtaining a porous support with a smooth surface.

[0085] The present invention has no particular limitation on the specific method of polishing, and the polishing can be performed according to conventional methods in the art.

[0086] In the present invention, the "first", "second" and "third" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0087] The third aspect of the present invention provides an application of the silica hybrid membrane described in the first aspect or the silica hybrid membrane prepared by the preparation method described in the second aspect in gas separation and purification, preferably in hydrogen separation and purification.

[0088] The silicon dioxide hybrid membrane of the present invention is applied to hydrogen separation and has high hydrogen selectivity.

[0089] The present invention will be described in detail below through examples.

[0090] In the following embodiments,

[0091] Gas permeability = (gas flux) / (membrane area × pressure difference);

[0092] Where, gas flux, mol / s; membrane area, m 2 ; Pressure difference, Pa;

[0093] H2 / N2 selectivity = H2 permeability / N2 permeability;

[0094] H2 / C3H8 selectivity = H2 permeability / C3H8 permeability.

[0095] Example 1

[0096] (1) Preparation of inorganic silica sol: First, add 8.3 g of anhydrous ethanol to 5 g of tetraethyl orthosilicate (TEOS), then dropwise add a mixture of 0.272 g of HNO3 and 10.627 g of deionized water, and then reflux in a 60°C water bath for 3 h to obtain TEOS sol.

[0097] (2) Preparation of LaNi-TEOS sol: 1.237 g of Ni(NO3)3·6H2O and 0.237 g of La(NO3)3·6H2O were fully dissolved in 8.3 g of anhydrous ethanol, then dropped into TEOS sol and refluxed in a 60°C water bath for 5 h to obtain LaNi-TEOS sol.

[0098] (3) Preparation of transition layer: First, the sheet ceramic carrier (α-Al2O3) was calcined at 550°C for 0.5h, and then SiO2-ZrO2 sol (Si / Zr molar ratio = 1, concentration 0.5wt.%) was coated on the calcined sheet ceramic carrier by wiping method, and then calcined at 550°C for 20min to obtain the transition layer.

[0099] (4) LaNi-TEOS sol was rubbed onto the transition layer with absorbent cotton and then calcined at 550°C for 60 min to obtain a separation layer. That is, a hybrid membrane was obtained. The characteristic parameters of the hybrid membrane are shown in Table 1.

[0100] The XRD pattern of the LaNi-TEOS xerogel of Example 1 is exemplified as follows: Figure 1 It can be seen that the peaks of 2θ=37.21°, 43.21°, 62.81°, 75.31° and 79.21° of LaNi-TEOS are distributed at 111, 200, 220, 311 and 222 of NiO crystal planes, respectively, indicating that Ni is successfully doped in the SiO2 network in the form of NiO.

[0101] The XPS diagram of the LaNi-TEOS xerogel of Example 1 is exemplified as follows: Figure 2 As shown. It can be seen that the O peak deconvolution shows that there are two peaks representing the main bond: Si-O-Si (532.3~532.8eV) and Si-O-La (531.1~531.4eV). The peak with a binding energy between SiO2 (532.8eV) and La2O3 (529.8eV) is Si-O-La, representing the formation of a valence bond.

[0102] The obtained hybrid membrane was subjected to gas testing, where N2, H2, and C3H8 gases were continuously introduced into the membrane assembly heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0103] Example 2

[0104] (1) Preparation of inorganic silica sol: First, add 6.8 g of anhydrous ethanol to 5 g of tetraethyl orthosilicate (TEOS), then dropwise add a mixture of 0.272 g of HNO3 and 10.627 g of deionized water, and then reflux in a 55°C water bath for 2 h to obtain TEOS sol.

[0105] (2) Preparation of LaAl-TEOS sol: 2.092 g of Al(NO3)3·9H2O and 0.128 g of La(NO3)3·6H2O were fully dissolved in 12.6 g of anhydrous ethanol, then dropped into the above TEOS sol and refluxed in a 60°C water bath for 4 h to obtain LaAl-TEOS sol.

[0106] (3) Preparation of transition layer: First, the sheet ceramic carrier (α-Al2O3) was calcined at 500°C for 0.5h, and then SiO2-ZrO2 sol (Si / Zr molar ratio = 0.5, concentration 1wt%) was coated on the calcined sheet ceramic carrier by wiping method, and then calcined at 500°C for 20min to obtain the transition layer.

[0107] (4) LaAl-TEOS sol was rubbed onto the transition layer with absorbent cotton and then calcined at 500°C for 60 min to obtain a separation layer. At this time, a hybrid membrane was obtained. The characteristic parameters of the hybrid membrane are shown in Table 1.

[0108] The obtained hybrid membrane was subjected to gas testing, where N2, H2, and C3H8 gases were continuously introduced into the membrane assembly heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0109] Example 3

[0110] The method of Example 1 was followed, except that the amount of La(NO3)3·6H2O was changed to 0.078 g, so that the mass ratio of metal R to metal M in the separation membrane was 1:10 in terms of elements.

[0111] The obtained hybrid membrane was subjected to gas testing, where N2, H2, and C3H8 gases were continuously introduced into the membrane assembly heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0112] Comparative Example 1

[0113] The method of Example 1 was followed, except that step (2) was omitted and the prepared inorganic silica sol (TEOS sol) was directly applied on the transition layer to obtain a separation layer. The characteristic parameters of the hybrid membrane are shown in Table 1.

[0114] The XRD pattern of the TEOS dry gel of Comparative Example 1 is as follows: Figure 1 It can be seen that there is a broad peak in the 2θ range of 20°-30°, indicating that the SiO2 network has amorphous characteristics.

[0115] The XPS diagram of the TEOS dry gel of Comparative Example 1 is as follows: Figure 2 As shown in Figure 2, it can be seen that the deconvolution of the O peak shows the existence of Si-O-Si (532.3-532.8 eV) bonds in the SiO2 network.

[0116] The obtained membrane was subjected to gas testing, and N2, H2, and C3H8 gases were continuously introduced into the membrane module heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0117] Comparative Example 2

[0118] The method of Example 1 was followed, except that step (2) was changed to preparing La-TEOS sol: 1.203 g of La(NO3)3·6H2O was fully dissolved in 8.3 g of anhydrous ethanol, then dropped into the TEOS sol, and refluxed in a 60°C water bath for 5 h to prepare La-TEOS sol.

[0119] The XRD pattern of the La-TEOS dry gel of Comparative Example 2 is as follows: Figure 1 As shown, it can be seen that La-TEOS does not have the crystallization characteristic peaks of La2O3 or related hydroxides.

[0120] The XPS diagram of the La-TEOS dry gel of Comparative Example 2 is as follows: Figure 2 As shown. It can be seen that the O peak deconvolution shows that there are only two peaks representing the main bonds: Si-O-Si (532.3-532.8 eV) and Si-O-La (531.1-531.4 eV), which is consistent with the results of Example 1. It is fully proved that the metal lanthanum exists in the SiO2 network in the form of valence bonds.

[0121] The characteristic parameters of the hybrid membrane are shown in Table 1.

[0122] The obtained hybrid membrane was subjected to gas testing, where N2, H2, and C3H8 gases were continuously introduced into the membrane assembly heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0123] Comparative Example 3

[0124] The method of Example 1 was followed, except that step (2) was changed to prepare Ni-TEOS sol, 1.791 g of Ni(NO3)3·6H2O was fully dissolved in 8.3 g of anhydrous ethanol, then dropped into TEOS sol, and refluxed in a 60°C water bath for 5 h to prepare Ni-TEOS sol. Ni-TEOS sol was calcined at 500°C for 60 min to obtain Ni-TEOS xerogel.

[0125] The XRD pattern of the Ni-TEOS dry gel of Comparative Example 3 is as follows: Figure 1 It can be seen that the peaks of 2θ=37.21°, 43.21°, 62.81°, 75.31° and 79.21° of Ni-TEOS are distributed at NiO crystal planes 111, 200, 220, 311 and 222, respectively, which is consistent with the results of Example 1, that is, the nickel exists in the form of NiO.

[0126] The XPS diagram of the Ni-TEOS dry gel of Comparative Example 3 is as follows: Figure 2 As shown. It can be seen that peak deconvolution shows that there is only one peak representing the main bond: Si-O-Si (532.3~532.8eV), so the metal nickel does not exist in the form of a valence bond, but forms a metal oxide.

[0127] The characteristic parameters of the hybrid membrane are shown in Table 1.

[0128] The obtained hybrid membrane was subjected to gas testing, where N2, H2, and C3H8 gases were continuously introduced into the membrane assembly heated at 200°C, and the gauge pressure on the raw material side was controlled to be 200 kPa. After stabilization for 1 hour, the gas permeability and selectivity were measured. The results are shown in Table 2.

[0129] Table 1

[0130]

[0131] Note: A represents the ratio of the mass of silicon oxide in the separation layer in terms of silicon element to the total mass of metal in terms of element.

[0132] Table 2

[0133]

[0134] It can be seen from the results in Table 2 that the application of the silica hybrid membrane of the present invention in hydrogen separation has significantly higher H2 / N2 selectivity and H2 / C3H8 selectivity.

[0135] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A silicon dioxide hybrid membrane, the hybrid membrane comprising a porous support, a transition layer and a separation layer; the transition layer comprises silicon zirconium oxide; the separation layer comprises silicon oxide, metal R and metal M, the metal R is selected from lanthanide metal elements, and the metal M is selected from at least one of Group VIII, Group IIA and Group IIIA metal elements.

2. The hybrid membrane according to claim 1, wherein In the separation layer, the metal R exists in the form of Si-OR covalent bonds, and the metal M exists in the form of oxides.

3. The hybrid membrane according to claim 1, wherein The average pore size of the porous support is 0.1-1 μm; Preferably, the average pore size of the transition layer is 2-10 nm; Preferably, the average pore size of the separation layer is less than 2 nm, preferably 0.5-1.5 nm.

4. The hybrid membrane according to any one of claims 1 to 3, wherein: The metal R is selected from at least one of lanthanum, cerium and neodymium, preferably lanthanum; Preferably, the metal M is selected from at least one of cobalt, nickel, magnesium and aluminum, preferably nickel; Preferably, in the separation layer, the ratio of the mass of silicon oxide calculated as silicon element to the total mass of metal calculated as element is 1-5:1, preferably 1.5-4:1; Preferably, the mass ratio of metal R to metal M, calculated as elements, is 1:1-15, preferably 1:2-8; Preferably, in the silicon-zirconium oxide, the silicon-zirconium molar ratio is 0.5-10; Preferably, the porous support is alumina.

5. A method for preparing a silicon dioxide hybrid film, the method comprising: (1) in the presence of a first solvent, subjecting an inorganic silica sol, a metal R compound and a metal M compound to a first reaction to obtain a bimetallic / inorganic silica sol, wherein the metal R is selected from a lanthanide metal element, and the metal M is selected from at least one of a group VIII, group IIA and group IIIA metal element; (2) coating the silicon zirconium sol onto a porous support, and then performing a first calcination to obtain a transition layer; (3) coating the bimetallic / inorganic silica sol obtained in step (1) on the transition layer, and then performing a second calcination to obtain a separation layer.

6. The method according to claim 5, wherein: The average pore size of the porous support is 0.1-1 μm; Preferably, the average pore size of the transition layer is 2-10 nm; Preferably, the average pore size of the separation layer is less than 2 nm, preferably 0.5-1.5 nm.

7. The method according to claim 5, wherein: Step (1) The conditions of the first reaction include: temperature of 45-65° C., time of 1-5 h; Preferably, the ratio of the mass of the inorganic silica sol calculated as silicon element to the total mass of the metal compound calculated as metal element is 1-5:1, preferably 1.5-4:1; Preferably, the mass ratio of the metal R compound to the metal M compound is 1:1-15, preferably 1:2-8, calculated on an element basis; Preferably, the metal R is selected from at least one of lanthanum, cerium and neodymium, preferably lanthanum; Preferably, the metal M is selected from at least one of cobalt, nickel, magnesium and aluminum, preferably nickel; Preferably, the metal R compound and the metal M compound are each independently selected from at least one of nitrates, sulfates and hydrochlorides.

8. The method according to any one of claims 5 to 7, wherein: The method for preparing the inorganic silica sol comprises: subjecting a silicon source, water, an acid and a second solvent to a second reaction; Preferably, the conditions of the second reaction include: temperature of 40-65°C and time of 2-8h; Preferably, the molar ratio of silicon source, H2O and acid calculated as silicon element is 1:20-30:0.05-0.2; Preferably, the acid is an inorganic acid, preferably at least one selected from nitric acid, sulfuric acid and hydrochloric acid; Preferably, the silicon source is selected from at least one of ethyl orthosilicate, methyl orthosilicate, tetraethyl silicate and ethyl methyl silicate.

9. The method according to any one of claims 5 to 8, wherein: The silicon-zirconium molar ratio of the silicon-zirconium sol is 0.5-10; Preferably, the concentration of the silicon zirconium sol is 0.5-10wt%; Preferably, the porous support is alumina; Preferably, the conditions of the first calcination in step (2) and the second calcination in step (3) each independently include: a temperature of 500-600° C. and a time of 20-60 minutes.

10. The method according to any one of claims 5 to 9, wherein: The method further comprises: before coating the silicon zirconium sol onto the porous support, calcining the porous support; Preferably, the calcination treatment conditions include: a temperature of 500-600° C. and a time of 0.5-10 h.

11. Use of the silica hybrid membrane according to any one of claims 1 to 4 or the silica hybrid membrane prepared by the preparation method according to any one of claims 5 to 10 in gas separation and purification, preferably in hydrogen separation and purification.

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