A hydrofining catalyst, its preparation method and application in oil product refining and regulation of aromatic ring saturation degree

Abstract

The application discloses a kind of hydrofining catalyst and its preparation method and the hydrofining catalyst made by the method, the main active component of traditional hydrofining catalyst such as W and Mo is not contained in the hydrofining catalyst, active component is cheap Fe, Co and Ni, carrier is also cheap silica.The catalyst is characterized in that the form of existence of metal active component is polyhedron crystal.And by modifying carrier, adding front transition metal oxide CeO2, Ta2O5And Nb2O5, it can be used to adjust aromatic ring saturation degree in oil product refining process.The method provided by the application can greatly reduce catalyst cost, and can improve the hydrofining activity of catalyst, and also can adjust aromatic ring saturation degree in hydrofining process.

Description

TECHNICAL FIELD

[0001] The present application relates to a low-cost hydrofining catalyst, a preparation method thereof and application thereof in oil product refining and regulation of aromatic ring saturation. BACKGROUND

[0002] With the emphasis on environmental protection by human beings, the production of clean energy is the trend of the times. Environmental protection regulations also make more and more stringent requirements on the quality of transportation fuels such as gasoline and diesel. This makes oil refining enterprises constantly put forward higher requirements on the activity and stability of hydrofining catalysts. Hydrofining technology can effectively remove sulfur, nitrogen and other impurities in oil products, which can not only meet the quality requirements of vehicle fuels, but also meet the processing needs of downstream chemical industry, and is the most commonly used clean oil production technology for current refining enterprises. In the current oil product quality requirements in China, reducing aromatics is the trend of the times. However, at the same time, we also see that the vigorous development of new energy vehicles makes most of the naphtha components unable to enter the original gasoline pool, thereby being converted into chemical raw materials. As chemical raw materials, the aromatics in distillate oil are valuable chemical resources. Therefore, how to effectively preserve the aromatic ring during hydrofining and improve its value as a chemical raw material is the focus of attention for refining enterprises. Therefore, it is required that refining enterprises can regulate the saturation of aromatics in the product while removing sulfur, nitrogen and other impurities according to different market demands. In addition, economic benefit is one of the most important indicators for refining enterprises, therefore, developing more efficient and low-cost catalysts is the most effective means to improve the technical economy of distillate oil hydrofining.

[0003] The hydrogenation catalysts used in the current refining industry are mainly active metals of Mo or W and auxiliary active metals of Co or Ni. Through the combination of them, the hydrogenation active phase is obtained after sulfidation. The carrier used is mainly active alumina. In the traditional cognition, it is generally believed that the active site of hydrodesulfurization is MoS2 or WS2, and Co or Ni mainly plays a role of auxiliary catalyst (DFT Calculations of Unpromoted and Promoted MoS2-Based Hydrodesulfurization Catalysts, Journal of Catalysis, 1999, 187, 109), and is not the main active site, and its ability to break C-S bond alone is weak. In addition, in the prior art, for example, the recently disclosed CN111715232A, CN108620085B, CN111821991A, CN107961796B and CN111939921A, etc., are all active phases of Mo or W as main metals, and the content is generally about 20 wt%. Since the prices of W and Mo are higher than those of Co and Ni, a large part of the cost of the catalyst comes from W and Mo. Therefore, it is particularly important to develop a low-cost catalyst with high desulfurization activity.

[0004] In the process of hydrogenation desulfurization of benzothiophene, it is generally believed that there are two reaction paths, one is the hydrogenation desulfurization (HYD) path, that is, the benzene ring is first hydrogenated and saturated, and then the C-S bond is broken to obtain non-aromatic products. The other is direct desulfurization (DDS), that is, the C-S bond is directly broken to generate aromatic products. In the HYD path, not only the aromatic content in the product is reduced, but also the hydrogen consumption is increased, and the cost is increased. However, if it is used as oil, this path will greatly reduce the aromatic content, which meets the demand of vehicle fuel for aromatic content. Therefore, it is also important to change the product distribution in the hydrogenation process by changing the catalyst formula. SUMMARY

[0005] Based on the above facts, the first object of the present application is to provide a hydrogenation catalyst which does not contain W, Mo and other elements, but only contains inexpensive Fe, Co and Ni metals, and has high desulfurization and denitrification activity and high stability, and is particularly suitable for the hydrogenation process of various distillate oils. At the same time, by introducing the front transition metals CeO2, Ta2O5 and Nb2O5, the saturation degree of aromatic ring in the hydrogenation process can be controlled.

[0006] The second object of the present application is to provide a preparation method of the hydrogenation catalyst.

[0007] The third object of the present application is to provide a new application of the hydrofining catalyst.

[0008] To achieve the above-mentioned first object, the present application adopts the following technical solutions:

[0009] A low-cost non-W, Mo hydrofining catalyst, which does not contain the traditionally recognized hydrofining active components W and Mo, and the metal active component of the hydrofining catalyst is one or several oxides of Group VIII metals Fe, Co and Ni, and the carrier is SiO2. Among them, when adjusting the aromatic ring saturation degree in the oil refining process, the catalyst active component also needs to add one or several of the oxides of the early transition metals CeO2, Ta2O5 and Nb2O5.

[0010] Optionally, the catalyst contains 1-50 wt% of metal oxides based on the total weight of the catalyst; preferably, the catalyst contains 2-10 wt% of metal oxides based on the total weight of the catalyst. Among them, the oxides are one or several oxides of Fe, Co and Ni.

[0011] Optionally, the carrier is SiO2, which can be one or several of various silica materials, including nanosilica, microporous silica and mesoporous silica; preferably, the silica is nanosilica.

[0012] Optionally, when the aromatic ring saturation degree needs to be adjusted while removing sulfur and nitrogen in hydrofining, the above catalyst also contains one or several of the oxides of the early transition metals CeO2, Ta2O5 and Nb2O5, and the content of one or several of the oxides of the early transition metals CeO2, Ta2O5 and Nb2O5 is 0-99 wt% based on the total weight of the catalyst according to the different aromatic ring saturation degrees.

[0013] To achieve the above-mentioned second object, the present application adopts the following technical solutions:

[0014] The preparation method of the hydrofining catalyst comprises the following steps:

[0015] The catalyst preparation can adopt impregnation method, sol-gel method or coprecipitation method.

[0016] Optionally, the impregnation method comprises the following steps:

[0017] Dissolve one or several of the soluble precursors containing the metal active components Fe, Co and Ni in water or ethanol or a mixture of water and ethanol to obtain a uniform mixed solution A;

[0018] Impregnate the carrier with A, dry and calcine to obtain the hydrofining catalyst.

[0019] Optionally, the sol-gel method includes the following steps:

[0020] One or more of the soluble precursors containing the metal active components Fe, Co, and Ni are dissolved in water, ethanol, or a mixture of water and ethanol to obtain a homogeneous mixed solution B.

[0021] A precursor containing SiO2 and citric acid are dissolved or dispersed in water to obtain mixture C;

[0022] C and B are mixed evenly and stirred thoroughly until a gel is formed. The resulting gel is dried and calcined to obtain the hydrogenation refining catalyst.

[0023] Optionally, the coprecipitation method includes the following steps:

[0024] One or more of the soluble precursors containing the metal active components Fe, Co, and Ni, or the precursor containing SiO2, are dissolved or dispersed in water, ethanol, or a mixture of water and ethanol to obtain a homogeneous mixed solution D.

[0025] A certain amount of alkali is dissolved in water to obtain solution E;

[0026] Solutions D and E were mixed dropwise to obtain a precipitate, which was then dried and calcined to obtain the hydrogenation refining catalyst.

[0027] Optionally, the soluble precursors of Fe, Co, and Ni in the above preparation method are their corresponding soluble salts, preferably one or more of their corresponding nitrates, chlorides, sulfates, and acetates.

[0028] Optionally, the SiO2 precursor mentioned in the above preparation method can be one or more of silica sol, water glass, and tetraethyl orthosilicate.

[0029] Optionally, the alkali mentioned in the above preparation method can be one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia water; preferably, it is ammonia water.

[0030] Optionally, the drying temperature described in the above preparation method is 60-120℃.

[0031] Optionally, the calcination temperature described in the above preparation method is 300-800℃; preferably 350-650℃.

[0032] A catalyst for adjusting the aromatic ring saturation in the hydrorefining process is prepared by introducing one or more of the following pre-transition metal oxides: CeO2, Ta2O5, and Nb2O5, into the above preparation method.

[0033] Optionally, the method for introducing the intermediate transition metal oxides CeO2, Ta2O5 and Nb2O5 into the catalyst for adjusting the aromatic ring saturation in the hydrorefining process is as follows: in the catalyst preparation method, a certain amount of one or more soluble precursors of soluble intermediate transition metal oxides CeO2, Ta2O5 and Nb2O5 are added to solutions A, C and D respectively.

[0034] Optionally, the soluble precursors of the pre-transition metal oxides CeO2, Ta2O5, and Nb2O5 are their corresponding nitrates, chlorides, and organic ligand salts. Preferably, the organic ligand salts are one or more of oxalate, tartrate, citrate, and malate.

[0035] To achieve the third objective mentioned above, the present invention also provides the application of the above-mentioned hydrotreating catalyst in the hydrorefining process of distillate oil.

[0036] Optionally, the distillate oil is a reforming pretreatment feedstock, gasoline, kerosene, straight-run diesel, secondary processed diesel, or wax oil.

[0037] Optionally, the hydrotreating catalyst is used in the hydrorefining process of light distillate oils and middle distillate oils for purposes such as hydrodesulfurization, hydrodenitrogenation, olefin saturation, and aromatics retention.

[0038] The beneficial effects of this invention are as follows:

[0039] According to one objective of the present invention, the hydrorefining catalyst provided herein does not contain W or Mo, but only relatively inexpensive active metal components Ni, Co, or Fe, thereby significantly reducing catalyst costs while achieving highly efficient desulfurization and denitrification. Regarding the control of aromatic ring saturation during hydrorefining, based on the aforementioned inexpensive catalyst, the addition of pre-transition metals CeO2, Ta2O5, or Nb2O5 can reduce aromatic ring saturation during hydrorefining, maximizing the retention of aromatics and improving the economic viability as a chemical feedstock. According to another objective of the present invention, the catalyst preparation methods provided herein are diverse, flexible, and simple. Regardless of the method, effective dispersion and exposure of the active metal components can be achieved, thereby improving catalyst performance. According to yet another objective of the present invention, the hydrorefining catalyst provided herein can be effectively used in the hydrorefining reaction of catalytic distillate oils. Attached Figure Description

[0040] Figure 1 This is a SEM image of the NS-1 catalyst.

[0041] Figure 2 This is a SEM image of the NNS-5 catalyst. Detailed Implementation

[0042] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment provides a supported hydrogenation catalyst, which is obtained by calcining an impregnated catalyst. The designed active metal oxide content of the catalyst, based on the total weight of the catalyst, is: NiO: 10wt%. The preparation method includes the following steps:

[0045] 18.6 g of tetraethyl orthosilicate and 5.318 g of citric acid were mixed, heated and stirred at 60 °C until a gel was formed, and dried in an oven at 100 °C. The dried and ground silica support was placed in a crucible and calcined in a muffle furnace at 500 °C for 5 h to obtain the support for later use. 0.779 g of nickel nitrate was dissolved in 10 mL of deionized water and stirred until dissolved evenly. 1.8 g of silica support was weighed and poured into the nickel nitrate solution, stirred for 12 h, and then dried in an oven at 100 °C. After drying, it was removed and ground. Under air atmosphere, it was calcined in a muffle furnace at 450 °C for 4 h to obtain a supported hydrogenation catalyst, denoted as NS-1. The amount of salt of the active metal component in the impregnation solution was determined according to the designed active metal content. During the impregnation process, there will be a loss of 1-3 wt% (based on the total weight of the catalyst) of the salt of the active metal component. The following examples and comparative examples are the same.

[0046] Example 2

[0047] This embodiment provides a supported hydrogenation catalyst, which is obtained by calcining an impregnated catalyst. The designed active metal oxide content of the catalyst, based on the total weight of the catalyst, is: NiO: 10wt%, Nb₂O₅: 10wt%. The preparation method includes the following steps: 9.406g of niobium citrate soluble precursor and 5.603g of tetraethyl orthosilicate are mixed, heated and stirred at 60°C until a gel is formed, and dried in a 100°C oven. The dried and ground niobium-silicon support is placed in a crucible and calcined in a muffle furnace at 500°C for 5 hours to obtain the support for later use. 0.779g of nickel nitrate is dissolved in 10mL of deionized water and stirred until dissolved evenly. 1.8g of niobium-silicon support is weighed and poured into the nickel nitrate solution, stirred for 12 hours, and then dried in a 100°C oven. After drying, it is removed and ground. The catalyst is then calcined in an air atmosphere at 450°C for 4 hours to obtain the supported hydrogenation catalyst, denoted as NNS-2.

[0048] Example 3. This example provides a supported hydrogenation catalyst, which is obtained by calcining an impregnated catalyst. The designed active metal oxide content of the catalyst, based on the total weight of the catalyst, is: NiO: 10wt%, Nb₂O₅: 20wt%. The preparation method includes the following steps: 18.811g of niobium citrate soluble precursor and 13.869g of tetraethyl orthosilicate are mixed, heated and stirred at 60°C until a gel is formed, and dried in a 100°C oven. The dried and ground niobium-silicon support is placed in a crucible and calcined in a muffle furnace at 500°C for 5 hours to obtain the support for later use. 0.779g of nickel nitrate is dissolved in 10mL of deionized water, stirred until dissolved evenly, and then set aside. 1.8g of niobium-silicon support is weighed and poured into the nickel nitrate solution, stirred for 12 hours, and then dried in a 100°C oven. After drying, it is removed and ground. Under air atmosphere, it is calcined in a muffle furnace at 450°C for 4 hours to obtain the supported hydrogenation catalyst, denoted as NNS-3.

[0049] Example 4

[0050] This embodiment provides a supported hydrogenation catalyst, which is obtained by calcining an impregnated catalyst. Based on the total weight of the catalyst, the designed active metal oxide content of the catalyst is: NiO: 10wt%, Nb₂O₅: 30wt%. The preparation method includes the following steps:

[0051] 28.217 g of niobium citrate soluble precursor and 12.136 g of tetraethyl orthosilicate were mixed, heated and stirred at 60 °C to form a gel, and dried in an oven at 100 °C. The dried and ground niobium-silicon support was placed in a crucible and calcined in a muffle furnace at 500 °C for 5 h to obtain the support for later use. 0.779 g of nickel nitrate was dissolved in 10 mL of deionized water and stirred until dissolved. 1.8 g of niobium-silicon support was weighed and poured into the nickel nitrate solution, stirred for 12 h, and then dried in an oven at 100 °C. After drying, it was removed and ground. Under air atmosphere, it was calcined in a muffle furnace at 450 °C for 4 h to obtain the supported hydrogenation catalyst, denoted as NNS-4.

[0052] Example 5

[0053] This embodiment provides a supported hydrogenation catalyst, which is obtained by calcining an impregnated catalyst. Based on the total weight of the catalyst, the designed active metal oxide content of the catalyst is: NiO: 10wt%, Nb₂O₅: 89wt%. The preparation method includes the following steps:

[0054] The niobic acid precursor was filtered and dried to obtain a filter cake, and 14.5 g was weighed and set aside. 11.3 g of oxalic acid was weighed and dissolved in an appropriate amount of water. The filter cake was added to the dissolved oxalic acid solution and stirred until clear to obtain niobium oxalate. 0.71 g of diammonium oxalate was added to the niobium oxalate solution, and water was added and stirred until clear. The clarified liquid was poured into a liner, 1.0 g of tetraethyl orthosilicate was added, and the mixture was placed in a crystallization vessel and crystallized in an oven at 180 °C for 24 h. Then, it was calcined in a muffle furnace at 400 °C for 3 h to prepare a support. 0.779 g of nickel nitrate was dissolved in 10 mL of deionized water and stirred until dissolved evenly. 1.8 g of the support was weighed and poured into the nickel nitrate solution. After stirring for 12 h, it was dried in an oven at 100 °C. After drying, it was removed and ground. Under air atmosphere, it was calcined in a muffle furnace at 450 °C for 4 h to obtain a supported hydrogenation catalyst, designated NNS-5.

[0055] Example 6

[0056] This embodiment provides a supported hydrogenation catalyst obtained by the sol-gel method. The catalyst, based on its total weight, has a designed active metal oxide content of 10 wt% NiO. The preparation method includes the following steps:

[0057] 18.6 g of tetraethyl orthosilicate, 5.318 g of citric acid, and 1.69 g of nickel nitrate were mixed in water, heated and stirred at 60 °C to form a gel, and dried in an oven at 100 °C. The dried and ground sample carrier was placed in a crucible and calcined in a muffle furnace at 450 °C for 4 h to obtain a supported hydrogenation catalyst, denoted as SG-1.

[0058] Example 7

[0059] This embodiment provides a supported hydrogenation catalyst obtained by co-precipitation. The catalyst, based on its total weight, has a designed active metal oxide content of 10 wt% NiO. The preparation method includes the following steps:

[0060] 18.6 g of tetraethyl orthosilicate and 1.69 g of nickel nitrate were mixed in water, and 1.0 M sodium hydroxide solution was added dropwise until complete precipitation. The precipitate was filtered, washed, and dried in an oven at 100 °C. The dried and ground sample support was placed in a crucible and calcined in a muffle furnace at 450 °C for 4 h to obtain a supported hydrogenation catalyst, denoted as CP-1.

[0061] Example 8

[0062] This embodiment provides a supported hydrogenation catalyst obtained by co-precipitation. The designed active metal oxide content of the catalyst, based on the total weight of the catalyst, is: NiO: 10wt%, CeO2: 89wt%, SiO2: 1wt%. The preparation method includes the following steps: 0.21g of tetraethyl orthosilicate, 1.69g of nickel nitrate, and 10.43g of cerium nitrate hexahydrate are mixed in water, and 1.0M sodium hydroxide solution is added dropwise until complete precipitation. The obtained precipitate is filtered, washed, and dried in a 100℃ oven. The dried and ground sample support is placed in a crucible and calcined in a muffle furnace at 450℃ for 4 hours to obtain the supported hydrogenation catalyst, denoted as NCS-1.

[0063] Comparison Column 1

[0064] The preparation method is the same as in Example 1, except that the support is replaced with γ-Al2O3, and the resulting catalyst is denoted as R-1.

[0065] Comparative Example 2

[0066] The preparation method is the same as in Example 1, except that the support is replaced with H-type Y molecular sieve, and the resulting catalyst is designated as R-2.

[0067] Reference List 3

[0068] The commercial NiMo / Al2O3 catalyst used is designated R-3.

[0069] Experiment 1

[0070] This experimental example provides an evaluation of the application of the catalysts of Examples 1-8, Comparative Examples 1-2, and Reference Example 1 in the hydrogenation treatment of dibenzothiophene.

[0071] The catalysts in Examples 1-8, Comparative Examples 1-2, and Reference Example 1 were all ground in a mortar and pestle before evaluation, pressed into tablets, sieved through a 40-60 mesh screen, and then pre-sulfurized to obtain sulfidated catalysts. Pre-sulfurization was carried out in a fixed-bed microreactor using a wet pre-sulfurization method. After pre-sulfurization, the catalyst was not removed but continued to undergo hydrogenation in the reactor. The pre-sulfurization oil was a cyclohexane solution containing 4 wt.% CS2. The pre-sulfurization temperature was 400°C, the sulfurization time was 12 h, the pressure was 3 MPa, and the liquid hourly space velocity was 6 h⁻¹. -1 The hydrogen-to-oil volume ratio is 700.

[0072] After sulfidation, the switching fluid was used to evaluate the hydrodesulfurization reaction of sulfur-containing substrates. The evaluation feedstock was a dibenzothiophene cyclohexane solution with a sulfur content of 1000 ppm. A twin-pump pump was used for injection, and the reaction conditions were: pressure 4.0 MPa, reaction temperature 340℃, hydrogen-to-oil volume ratio 600, and mass hourly space velocity 6 h⁻¹. -1After the reaction stabilized for 8 hours, samples were taken. The reactants were separated by a gas-liquid separator, and samples were collected from the bottom outlet of the separator for chromatographic analysis. The evaluation results of the hydrogenated catalyst are shown in Table 1.

[0073] Experiment Example 2

[0074] This experimental example is the same as Experiment 1, except that the feedstock was replaced with catalytic diesel oil with an sulfur content of 1921 ppm instead of dibenzothiophene. The catalysts used were NS-1 catalyst and R-1 reference. The results are shown in Table 2.

[0075]

[0076]

[0077] .

[0078] Table 1 shows that the supported hydrogenation catalysts prepared in Examples 1-7 of this invention possess high hydrodesulfurization performance under the same reaction conditions and the same active metal loading. Compared with comparative catalysts D-1 and D-2, the support has a significant impact on the hydrorefining performance of the catalyst; in this technical solution, only a silica support can achieve such excellent results. Examples 1-5 demonstrate that by adjusting the content of the preceding transition metal oxide, the aromatic saturation capacity of the hydrogenation catalyst can be flexibly adjusted, thereby achieving flexible product control. Compared with reference R-1, it can be seen that the catalyst provided by this technical solution can significantly reduce aromatic saturation, yielding more aromatic saturated products. Table 2 shows that, in catalytic diesel hydrorefining, the catalyst provided by this technical solution has higher desulfurization activity and lower aromatic saturation. Therefore, the method of this invention can, while ensuring catalyst reactivity, control the saturation degree of aromatic rings during hydrorefining by introducing a preceding transition metal, reducing hydrogen consumption and dependence on MoW, thus lowering catalyst production costs and demonstrating high economic benefits and long-term industrial application value.

Claims

1. The application of a low-cost non-W, Mo hydrorefining catalyst in the hydrorefining process of distillate oils, characterized in that, This hydrorefining catalyst does not contain the conventionally recognized hydrorefining active components W and Mo. The active metallic component of this catalyst is one or more oxides of Group VIII metals Fe, Co, and Ni, supported by SiO2, and exists as a polyhedral crystal. The catalyst also requires the addition of one or more of the pre-transition metal oxides CeO2, Ta2O5, and Nb2O5. Depending on the degree of aromatic ring saturation, the content of one or more of the pre-transition metal oxides CeO2, Ta2O5, and Nb2O5, based on the total weight of the catalyst, is greater than 0% and less than or equal to 99%. Based on the total weight of the catalyst, the catalyst contains 1-50 wt% of metal oxides; wherein the oxides are one or more of Fe, Co, and Ni oxides.

2. The application according to claim 1, characterized in that, The carrier is SiO2, including one or more of nano-silica, microporous silica, and mesoporous silica.

3. The application according to any one of claims 1-2, characterized in that, The preparation method of the hydrogenation refining catalyst is impregnation, sol-gel method or co-precipitation method.

4. The application according to claim 3, characterized in that, The impregnation method includes the following steps: One or more of the soluble precursors containing the metal active components Fe, Co, and Ni are dissolved in water, ethanol, or a mixture of water and ethanol to obtain a homogeneous mixed solution A. The carrier is mixed and impregnated with A, and then dried and calcined to obtain the hydrorefining catalyst.

5. The application according to claim 3, characterized in that, The sol-gel method includes the following steps: dissolving one or more of the soluble precursors containing the metal active components Fe, Co, and Ni in water, ethanol, or a mixture of water and ethanol to obtain a homogeneous mixed solution B. A precursor containing SiO2 and citric acid are dissolved or dispersed in water to obtain mixture C; C and B are mixed evenly and stirred thoroughly until a gel is formed. The resulting gel is dried and calcined to obtain the hydrogenation refining catalyst.

6. The application according to claim 3, characterized in that, The coprecipitation method includes the following steps: One or more of the soluble precursors containing the metal active components Fe, Co, and Ni, or the precursor containing SiO2, are dissolved or dispersed in water, ethanol, or a mixture of water and ethanol to obtain a homogeneous mixed solution D. A certain amount of alkali is dissolved in water to obtain solution E; Solutions D and E were mixed dropwise to obtain a precipitate, which was then dried and calcined to obtain the hydrogenation refining catalyst.

7. The application according to any one of claims 4-6, characterized in that, The soluble precursors of Fe, Co, and Ni are their corresponding soluble salts, which are one or more of nitrates, chlorides, sulfates, and acetates; the SiO2 precursor is one or more of silica sol, water glass, and tetraethyl orthosilicate.

8. The application according to claim 6, characterized in that, The alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia water; the drying temperature is 60-120℃; and the calcination temperature is 300-800℃.

9. The application according to claim 7, characterized in that, A certain amount of one or more soluble precursors of soluble pre-transition metal oxides CeO2, Ta2O5 and Nb2O5 are added to solutions A, C or D respectively; the soluble precursors of the pre-transition metal oxides CeO2, Ta2O5 and Nb2O5 are their corresponding nitrates, chlorides and organic ligand salts.

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