Method for preparing zeolite molecular sieve precursor from oil shale ash

Abstract

The invention discloses a method for preparing a zeolite molecular sieve precursor from oil shale ash. The method comprises the following steps: step 1, grinding and calcining the oil shale ash; 2, mixing the ground and calcined oil shale ash with solid sodium hydroxide particles, and activating; 3, heating and stirring the activated oil shale ash in a sodium hydroxide solution to remove impurities; step 4, standing the silicon-containing aluminum-iron filtrate, and filtering to remove iron to obtain a silicon-aluminum solution; step 5, dropwise adding an acid solution to obtain silica-alumina gel; 6, drying and grinding the silica-alumina gel to obtain zeolite molecular sieve precursor powder; according to the method for preparing the molecular sieve precursor from the oil shale ash, resource utilization of the oil shale ash can be achieved, meanwhile, high economical efficiency is achieved, and the purpose of environmental protection is achieved. The method has the advantages of high product purity, low capital investment, low operation cost and good economic benefit, and can be widely applied to the field of chemical industry.

Description

Technical Field

[0001] The invention discloses a method for preparing a zeolite molecular sieve precursor by utilizing oil shale ash, and relates to the technical field of solid waste resource utilization. Background Art

[0002] Oil shale ash is a byproduct of the process of burning oil shale for power generation, such as furnace ash, fly ash, or dry distillation for oil and gas production. It contains a large amount of minerals, mainly aluminum oxide and silicon oxide. However, the amount of oil shale ash produced by power generation or dry distillation in China is huge, accounting for almost 60-80% of the oil shale processing volume. The utilization of oil shale ash includes filling mines, making cement, red bricks, ceramsite and other building materials, but due to its low economic efficiency, a large amount of oil shale ash is accumulated, which causes serious pollution to the ecological environment and is also a serious waste of resources. Therefore, how to utilize oil shale ash more economically and environmentally friendly is a technical problem that needs to be solved urgently.

[0003] Natural zeolites are mainly used in agriculture, water and soil remediation, while synthetic zeolites have different industrial applications, mainly in the field of molecular sieve catalysis. Currently, more than 40% of acid-catalyzed reactions are based on synthetic zeolites. Zeolite molecular sieves are composed of aluminosilicates, including LTA type, FAU type, MOR type and MFI type. The conventional preparation of zeolite molecular sieves uses silicon source and aluminum source as raw materials, adds H2O, NaOH and template agent in different proportions according to demand, and performs hydrothermal synthesis at a certain reaction temperature and reaction time to obtain zeolite molecular sieves. In order to realize the resource utilization of solid waste, the preparation of zeolite molecular sieves using solid waste containing silicon and aluminum has become a hot topic of research today. The raw materials commonly used to prepare zeolite molecular sieves include fly ash, kaolin, coal gangue and oil shale ash, and the commonly used methods include direct hydrothermal method, alkali fusion-hydrothermal method and molten salt method. Among them, the conversion rate of synthesizing zeolite molecular sieves by molten salt method is low, resulting in irregular morphological structure of zeolite. The direct hydrothermal method is not suitable for oil shale ash with a high quartz content, resulting in low zeolite purity. Oil shale ash contains high levels of quartz and impurities (iron, calcium, magnesium, titanium), so the preparation of zeolite molecular sieves from it requires activating the inert quartz into active silica and removing the metal impurities to obtain high-purity zeolite molecular sieves.

[0004] Chinese patent number 200910220189.4, "A method for preparing zeolite molecular sieves using oil shale waste residue", discloses a method for preparing 13X type zeolite molecular sieves using oil shale waste residue. The process can be briefly described as follows: the oil shale waste residue is first acid-leached to obtain solid phase SiO2, then the aluminum sulfate crystals obtained by cooling and crystallizing the liquid phase are alkali-dissolved to obtain sodium aluminate solution, and finally the solid phase SiO2 is alkali-dissolved and mixed with the sodium aluminate solution to obtain the silica-alumina gel to prepare the zeolite molecular sieve. The above process technology first separates silicon and aluminum into solid phases and then dissolves them in sodium hydroxide. The heating temperature is high and the time is long, the amount of acid and alkali used is large, the process is complicated, the production cost is high, the equipment investment is huge, and the economic benefits are poor.

[0005] "Synthesis and Characterization of Oil Shale Ash-Based NaX Zeolite" (Zhao Xiaosheng et al., Coal and Chemical Industry, 2024, 45(7): 145-149+160) uses Huadian oil shale ash as raw material and alkali fusion-hydrothermal synthesis of NaX molecular sieve. This pretreatment method is not suitable for oil shale ash with higher impurity content. The presence of more impurities may cause the zeolite molecular sieve product to have low purity. The activated oil shale ash has a high alkalinity, and a large amount of sodium ions in the ash may make it impossible to synthesize specific zeolite molecular sieves (such as ZSM-5).

[0006] "Preparation and Application of ZSM-5 Molecular Sieve Using Fly Ash as Raw Material" (Zhao Caiyun et al., Industrial Catalysis, 2024, 32(3): 46-52.) Fly ash is used as raw material, and the pretreatment method is: activating fly ash by alkali fusion method and then adding water to dissolve and remove impurities. When water is used to dissolve and activate fly ash, the extraction rate of silicon and aluminum in fly ash is low, and the silicon and aluminum elements in fly ash cannot be fully utilized, resulting in a waste of resources. The alkali fusion method activates the iron in fly ash, and after adding water, the divalent iron ions are dissolved in the solution, and then participate in the synthesis of zeolite molecular sieves, resulting in impure products.

[0007] "Process conditions for hydrothermal synthesis of ZSM-5 zeolite from fly ash" (Wang Youhe et al., Industrial Catalysis, 2018, 26(5):110-116.) Fly ash is used as raw material, and the pretreatment method is acid washing-alkali fusion. This pretreatment method uses hydrochloric acid at 20°C for 5 hours, which has high energy consumption and poor impurity removal effect. At the same time, some aluminum elements are lost, and the direct discharge of used hydrochloric acid will cause resource waste and environmental pollution.

[0008] The synthesis processes of different types of zeolite molecular sieves vary greatly, and the silicon-aluminum ratio, alkalinity, aging time, hydrothermal temperature, reaction time and other factors are all different. The use of a single process to prepare molecular sieve precursors avoids the different process flows used to prepare different types of molecular sieves. For example, the preparation of high silicon-aluminum ratio molecular sieves requires acid washing and dealuminization of oil shale ash. Oil shale ash is used to prepare silicon-aluminum-rich molecular sieve precursors. Later, by adding H2O, templates and alkali solutions, and adding silicon / aluminum sources when necessary, it can be used to synthesize high-purity zeolite molecular sieves under any reaction conditions. Molecular sieve precursors prepared from oil shale ash are suitable for the preparation of various types of molecular sieves. Summary of the invention

[0009] In view of this, the present invention provides a method for preparing a zeolite molecular sieve precursor using oil shale ash, so as to realize resource utilization of oil shale ash, and the obtained molecular sieve precursor is suitable for the preparation of various types of molecular sieves.

[0010] The technical solution provided by the present invention is specifically a method for preparing a zeolite molecular sieve precursor using oil shale ash, comprising the following steps:

[0011] Step 1: Grinding and calcining the oil shale ash;

[0012] Step 2: mixing the ground and calcined oil shale ash with solid sodium hydroxide particles for activation;

[0013] Step 3: The activated oil shale ash is placed in a sodium hydroxide solution, heated and stirred to remove impurities, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron;

[0014] Step 4: let the filtrate containing silicon, aluminum and iron stand, filter and remove iron, and obtain a silicon-aluminum solution;

[0015] Step 5: adding an acid solution dropwise to the silica-alumina solution to obtain a silica-alumina gel;

[0016] Step 6: Dry and grind the silica-alumina gel to obtain zeolite molecular sieve precursor powder.

[0017] Preferably, in step 1, the oil shale ash is ground to a fineness of ≤100 mesh, calcined to 815° C. at a heating rate of 10° C. / min and maintained at this temperature for 2 hours.

[0018] Preferably, in step 2, the activation comprises: mixing the ground and calcined oil shale ash with solid sodium hydroxide particles in a mass ratio of 1.2 and grinding to a fineness of ≤200 mesh, and calcining at 650°C for 2h at a heating rate of 10°C / min to obtain activated oil shale ash.

[0019] Preferably, in step 3, the activated oil shale ash is added to a sodium hydroxide solution with a concentration of 2 to 8 mol / L to obtain a mixture, the mixture is heated at 40 to 60° C. while stirring for 40 min, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron; wherein the solid-to-liquid ratio of the activated oil shale ash to the sodium hydroxide solution is 1 g / 10 mL.

[0020] Preferably, the stirring speed is 400-800 rpm.

[0021] Preferably, the standing time in step 4 is 72 hours and the temperature is room temperature.

[0022] Preferably, in step 5, an acid solution is added dropwise to the silica-alumina solution until the pH of the silica-alumina solution is adjusted to 9-10 and a white precipitate appears, and then the pH-adjusted mixture is centrifuged to obtain a silica-alumina gel.

[0023] Preferably, the acid solution is any one of a sulfuric acid solution or a hydrochloric acid solution.

[0024] In a second aspect, the present invention also provides a zeolite molecular sieve precursor prepared by the method, wherein the mass proportion of metal impurities in the precursor is: Fe2O3 = 0.059-0.599%, CaO = 0.024-0.037%, MgO = 0-0.081%, TiO2 = 0%.

[0025] The present invention provides a method for preparing a molecular sieve precursor using oil shale ash. The method can realize resource utilization of oil shale ash, has high economic efficiency, and achieves the purpose of environmental protection. The method has high product purity, low infrastructure investment, low operating cost, good economic benefits, and can be widely used in the chemical industry.

[0026] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1A schematic flow chart of a method for preparing a zeolite molecular sieve precursor using oil shale ash provided in an embodiment of the present invention;

[0030] Figure 2 This is the XRD pattern of oil shale ash in Example 1;

[0031] Figure 3 This is the XRD pattern of activated oil shale ash in Example 1;

[0032] Figure 4 The XRD pattern of NaX zeolite molecular sieve in Example 2;

[0033] Figure 5 This is the SEM image of the NaX zeolite molecular sieve in Example 2;

[0034] Figure 6 The XRD pattern of ZSM-5 zeolite molecular sieve in Example 3;

[0035] Figure 7 This is the SEM image of the ZSM-5 zeolite molecular sieve in Example 3. DETAILED DESCRIPTION

[0036] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of methods consistent with some aspects of the present invention as detailed in the appended claims.

[0037] This embodiment first provides a method for preparing a zeolite molecular sieve precursor using oil shale ash, comprising the following steps:

[0038] Step 1: Grinding and calcining the oil shale ash;

[0039] Grind the oil shale ash to a fineness of ≤100 mesh, calcine it to 815℃ at a heating rate of 10℃ / min and keep it at this temperature for 2h to remove the residual organic matter in the oil shale ash; all organic matter can be removed at 815℃;

[0040] Step 2: mixing the ground and calcined oil shale ash with solid sodium hydroxide particles for activation;

[0041] The oil shale ash obtained in step 1 is mixed with solid sodium hydroxide particles at a mass ratio of 1.2 and ground to a fineness of ≤200 mesh, and the sodium hydroxide particles and the oil shale ash are uniformly mixed during the grinding process. Then, the oil shale ash is calcined at 650°C for 2 hours at a heating rate of 10°C / min to melt the inert quartz in the oil shale ash that affects the synthesis of zeolite molecular sieves with sodium hydroxide and converted into an active sodium silicate compound to obtain activated oil shale ash;

[0042] Step 3: The activated oil shale ash is placed in a sodium hydroxide solution, heated and stirred to remove impurities, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron;

[0043] The activated oil shale ash obtained in step 2 is added to a sodium hydroxide solution with a concentration of 2 to 8 mol / L, the solid-liquid ratio of the activated oil shale ash to the sodium hydroxide solution is 1 g / 10 mL, the mixture is heated in a water bath at 40 to 60° C. and stirred for 40 minutes, at high temperature and high alkali concentration, silicon, aluminum, and divalent iron in the activated oil shale ash are dissolved in the solution, while calcium, magnesium, and titanium are precipitated, and a metal impurity-containing filter residue and a silicon, aluminum, and iron-containing filtrate are obtained after filtration;

[0044] Step 4: let the filtrate containing silicon, aluminum and iron stand, filter and remove iron, and obtain a silicon-aluminum solution;

[0045] The green filtrate containing divalent iron obtained in step 3 is allowed to stand until it becomes colorless and forms a red trivalent iron precipitate, and the precipitate is filtered out to obtain a silicon-aluminum solution;

[0046] Step 5: adding an acid solution dropwise to the silica-alumina solution to obtain a silica-alumina gel;

[0047] Add the acid solution dropwise to the silica-alumina solution obtained in step 4, adjust the pH of the solution to 9-10 to produce a large amount of white silica-alumina precipitate, and centrifuge the mixture at 7000 r / min for 3 min to obtain silica-alumina gel;

[0048] Step 6: Dry and grind the silica-alumina gel to obtain zeolite molecular sieve precursor powder.

[0049] The silica-alumina gel obtained in step 5 is dried at 70° C. for 24 h, and ground to a fineness of ≤200 mesh to obtain a zeolite molecular sieve precursor powder, in which the mass proportions of metal impurities in the precursor are: Fe2O3=0.059-0.599%, CaO=0.024-0.037%, MgO=0-0.081%, and TiO2=0%.

[0050] The stirring speed in the above step 3 is 400-800 rpm.

[0051] The standing time of step 4 is 72 hours at room temperature.

[0052] The type of acid in the gel preparation process in step 5 is either sulfuric acid or hydrochloric acid.

[0053] The present invention uses industrial waste oil shale ash as raw material, and obtains a zeolite molecular sieve precursor by calcining to remove organic matter, alkali melting to activate quartz, and alkali dissolving and purifying, which not only realizes the resource utilization of oil shale ash, but also prepares a zeolite molecular sieve precursor that can be widely used. The present invention does not use the traditional method of extracting silicon dioxide and aluminum oxide from oil shale ash separately and then combining them to make gel as a raw material for zeolite synthesis, but removes impurities in oil shale ash without separating silicon and aluminum, simplifies the preparation process, avoids the steps of high temperature and long-term use of acid and alkali treatment, and the alkali solution used in the preparation process is neutralized, avoiding the large-scale discharge of acid and alkali residual liquid.

[0054] Example 1

[0055] Embodiment 1 of the present invention discloses a method for preparing an oil shale ash-based zeolite molecular sieve precursor, which specifically comprises the following steps:

[0056] (1) calcining the oil shale ash in a muffle furnace at a heating rate of 10°C / min to 815°C and maintaining the temperature for 2 hours, and grinding the calcined oil shale ash to less than 200 mesh;

[0057] (2) taking 5 g of calcined oil shale ash, mixing it with 6 g of NaOH and grinding it to a fineness of ≤200 mesh, and calcining the mixture at 650° C. for 2 h in a muffle furnace at a heating rate of 10° C. / min to obtain activated oil shale ash;

[0058] (3) 5 g of activated oil shale ash was dissolved in 50 mL of 2, 4, 6, and 8 mol / L sodium hydroxide solutions, respectively. The mixture was heated in a water bath at 40 and 60° C. and stirred at 400 rpm for 40 min. After filtering, a filter residue containing metal impurities and a filtrate containing silicon, aluminum, and iron were obtained.

[0059] (4) the filtrate containing silicon, aluminum and iron is allowed to stand for 72 hours until it becomes colorless and forms a precipitate, and the precipitate is filtered out to obtain a silicon-aluminum solution;

[0060] (5) adding sulfuric acid solution dropwise to the silica-alumina solution, adjusting the pH of the solution to 9-10 to produce a large amount of white precipitate, and centrifuging the mixture at 7000 r / min for 3 min to obtain silica-alumina gel;

[0061] (6) The silica-alumina gel was dried at 70° C. for 24 h and ground to a fineness of ≤200 mesh to obtain a zeolite molecular sieve precursor powder. The percentage of each component in the precursor is shown in the table below. It can be seen that the impurity removal effect of the zeolite precursor obtained by the steps of the present invention is good.

[0062] Table 1 Metal oxide content of oil shale ash and zeolite precursor

[0063]

[0064]

[0065] X-ray diffractometer (XRD) was used to characterize the oil shale ash before and after activation. The XRD spectrum shows that the diffraction peaks of quartz and Fe2O3 in the oil shale ash disappear after activation, indicating that quartz becomes an active substance after activation and iron does not exist in the form of trivalent iron.

[0066] Example 2

[0067] Embodiment 2 of the present invention discloses a method for preparing an oil shale ash-based zeolite molecular sieve precursor, which specifically comprises the following steps:

[0068] (1) using a pulverizer to refine the oil shale ash, collecting the oil shale ash passing through a 100-mesh sieve and calcining it in a muffle furnace, calcining it to 815° C. at a heating rate of 10° C. / min and maintaining it at this temperature for 2 h, and grinding the calcined oil shale ash to less than 200 mesh;

[0069] (2) taking 5 g of calcined oil shale ash, mixing it with 6 g of NaOH and grinding it to a fineness of ≤200 mesh, and calcining the mixture at 650° C. for 2 h in a muffle furnace at a heating rate of 10° C. / min to obtain activated oil shale ash;

[0070] (3) 5 g of activated oil shale ash was dissolved in 50 mL of 6 mol / L sodium hydroxide solution, the mixture was heated in a water bath at 60° C. and stirred at 400 rpm for 40 min, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron;

[0071] (4) the filtrate containing silicon, aluminum and iron is allowed to stand for 72 hours until it becomes colorless and forms a precipitate, and the precipitate is filtered out to obtain a silicon-aluminum solution;

[0072] (5) adding sulfuric acid solution dropwise to the silica-alumina solution, adjusting the pH of the solution to 9-10 to produce a large amount of white precipitate, and centrifuging the mixture at 7000 r / min for 3 min to obtain silica-alumina gel;

[0073] (6) Dry the silica-alumina gel at 70° C. for 24 h and grind it to a fineness of ≤200 mesh to obtain a zeolite molecular sieve precursor powder.

[0074] (7) Take 4 g of oil shale ash-based zeolite molecular sieve precursor, add 40 mL of 1 mol / L sodium hydroxide solution, stir the mixture evenly, transfer it to a 100 mL stainless steel reactor lined with polytetrafluoroethylene, and then place it in an oven for hydrothermal crystallization at 100 ° C for 24 h. After cooling, wash the product with deionized water until its pH value reaches 7-8, filter and dry to obtain NaX zeolite molecular sieve.

[0075] The product was characterized by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The XRD spectrum showed the diffraction peak of NaX, the product had high purity, and no diffraction peaks of other substances existed. The SEM image showed that the product was octahedral, which was the standard form of NaX molecular sieve.

[0076] Example 3

[0077] Embodiment 3 of the present invention discloses a method for preparing an oil shale ash-based zeolite molecular sieve precursor, which specifically comprises the following steps:

[0078] (1) using a pulverizer to refine the oil shale ash, collecting the oil shale ash passing through a 100-mesh sieve and calcining it in a muffle furnace, calcining it to 815° C. at a heating rate of 10° C. / min and maintaining it at this temperature for 2 h, and grinding the calcined oil shale ash to less than 200 mesh;

[0079] (2) taking 5 g of calcined oil shale ash, mixing it with 6 g of NaOH and grinding it to a fineness of ≤200 mesh, and calcining the mixture at 650° C. for 2 h in a muffle furnace at a heating rate of 10° C. / min to obtain activated oil shale ash;

[0080] (3) 5 g of activated oil shale ash was dissolved in 50 mL of 6 mol / L sodium hydroxide solution, the mixture was heated in a water bath at 60° C. and stirred at 400 rpm for 40 min, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron;

[0081] (4) the filtrate containing silicon, aluminum and iron is allowed to stand for 72 hours until it becomes colorless and forms a precipitate, and the precipitate is filtered out to obtain a silicon-aluminum solution;

[0082] (5) adding sulfuric acid solution dropwise to the silica-alumina solution, adjusting the pH of the solution to 9-10 to produce a large amount of white precipitate, and centrifuging the mixture at 7000 r / min for 3 min to obtain silica-alumina gel;

[0083] (6) Dry the silica-alumina gel at 70° C. for 24 h and grind it to a fineness of ≤200 mesh to obtain a zeolite molecular sieve precursor powder.

[0084] (7) Take 1 g of oil shale ash-based zeolite molecular sieve precursor,

[0085] SiO2:Al2O3:TPAOH:H2O=1:0.02:0.25:80 ratio is added with white carbon black as silicon source, template TPAOH and deionized water. After aging for 7 hours at room temperature, it is transferred to a 100mL stainless steel reactor lined with polytetrafluoroethylene, and then placed in an oven for hydrothermal crystallization at 170℃ for 36 hours. After cooling, the product is washed with deionized water until its pH value reaches 7-8, filtered and dried in an oven at 105℃ for 12 hours, and placed in a muffle furnace for calcination at 540℃ for 6 hours to remove the template, and a ZSM-5 zeolite molecular sieve is obtained.

[0086] The product was characterized by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The XRD spectrum showed the diffraction peak of ZSM-5, the product had high purity, and no diffraction peaks of other substances existed. The SEM image showed that the product was in the form of ZSM-5 molecular sieve.

[0087] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0088] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a zeolite molecular sieve precursor using oil shale ash, characterized in that: The steps include: Step 1: Grinding and calcining the oil shale ash; Step 2: mixing the ground and calcined oil shale ash with solid sodium hydroxide particles for activation; Step 3: The activated oil shale ash is placed in a sodium hydroxide solution, heated and stirred to remove impurities, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron; Step 4: let the filtrate containing silicon, aluminum and iron stand, filter and remove iron, and obtain a silicon-aluminum solution; Step 5: adding an acid solution dropwise to the silica-alumina solution to obtain a silica-alumina gel; Step 6: Dry and grind the silica-alumina gel to obtain zeolite molecular sieve precursor powder.

2. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 1, characterized in that: In step 1, the oil shale ash is ground to a fineness of ≤100 mesh, calcined to 815° C. at a heating rate of 10° C. / min and maintained at this temperature for 2 hours.

3. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 1, characterized in that: In step 2, the activation comprises: mixing the ground and calcined oil shale ash with solid sodium hydroxide particles in a mass ratio of 1.2 and grinding to a fineness of ≤200 mesh, and calcining at 650° C. for 2 hours at a heating rate of 10° C. / min to obtain activated oil shale ash.

4. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 1, characterized in that: In step 3, the activated oil shale ash is added to a sodium hydroxide solution with a concentration of 2 to 8 mol / L to obtain a mixture, the mixture is heated at 40 to 60° C. while stirring for 40 minutes, and filtered to obtain a filter residue containing metal impurities and a filtrate containing silicon, aluminum and iron; wherein the solid-liquid ratio of the activated oil shale ash to the sodium hydroxide solution is 1 g / 10 mL.

5. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 4, characterized in that: The stirring speed is 400-800 rpm.

6. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 4, characterized in that: The standing time in step 4 is 72 hours, and the temperature is room temperature.

7. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 1, characterized in that: In step 5, an acid solution is added dropwise to the silica-alumina solution until the pH of the silica-alumina solution is adjusted to 9-10 and a white precipitate appears, and then the pH-adjusted mixture is centrifuged to obtain a silica-alumina gel.

8. The method for preparing a zeolite molecular sieve precursor using oil shale ash according to claim 7, characterized in that: The acid solution is any one of a sulfuric acid solution and a hydrochloric acid solution.

9. The zeolite molecular sieve precursor prepared by the method according to any one of claims 1 to 8, characterized in that: The mass proportions of metal impurities in the precursor are: Fe2O3=0.059-0.599%, CaO=0.024-0.037%, MgO=0-0.081%, TiO2=0%.

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