Method for synthesizing zeolite molecular sieve through solid waste coal gangue in-situ crystallization

Abstract

The invention relates to the technical field of zeolite molecular sieve production, in particular to a method for synthesizing a zeolite molecular sieve through solid waste coal gangue in-situ crystallization. The method comprises the following steps: roasting coal gangue at 600-800 DEG C for 1-5 hours to obtain roasted coal gangue; mixing the coal gangue with acid and water in a ratio of 1: (0.1-0.5): (4-8), reacting at 65-95 DEG C for 1-5 hours, dropping alkali to adjust the pH value to 7-10, aging, filtering, washing and drying to obtain activated coal gangue; mixing the activated coal gangue with an external source, a template agent, a solid-phase seed crystal (the crystallinity is greater than or equal to 85%) and water in proportion, crystallizing for 24-72 hours at the temperature of 100-200 DEG C, roasting to obtain SAPO-34, SSZ-13 or AlPO4-5, and adding ammonium salt for ion exchange to prepare an MTO catalyst. The crystallization degree of the molecular sieve is improved, the methanol conversion rate of the MTO catalyst is larger than or equal to 96%, coal gangue recycling is achieved, cost is reduced, and the technology is universal and suitable for industrialization.

Description

Technical Field

[0001] This invention relates to the field of zeolite molecular sieve production technology, specifically a method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves. Background Technology

[0002] Zeolite molecular sieves, as a class of microporous materials with regular pore structures, occupy a core position in catalysis, adsorption separation, and ion exchange due to their unique topology, excellent surface acidity, and hydrothermal stability. Among them, SAPO-34 molecular sieve is a core catalyst in the methanol-to-olefins (MTO) process, which can efficiently convert methanol into low-carbon olefins; SSZ-13 molecular sieve, due to its CHA topology, exhibits excellent sulfur and water resistance in the field of SCR denitrification in motor vehicles; and AlPO4-5 molecular sieve, with its one-dimensional microporous structure, is widely used in highly selective adsorption and fine chemical catalysis.

[0003] Currently, in-situ crystallization is the mainstream technology for synthesizing zeolite molecular sieves. It uses natural clays such as kaolin as silicon and aluminum sources, combined with added phosphorus sources and template agents, to generate zeolite crystals in situ through calcination activation and crystallization reactions. However, the limited reserves of kaolin resources and the rising mining costs have constrained the low-cost development of the zeolite molecular sieve industry.

[0004] Coal gangue, a solid waste generated during coal mining and washing, has reserves exceeding 10 billion tons in my country. Its main components are Al2O3 and SiO2, which are highly compatible with kaolin. Furthermore, it is inexpensive and readily available, making it an ideal raw material for synthesizing zeolite molecular sieves as an alternative to kaolin. However, current technologies for in-situ crystallization synthesis of zeolite molecular sieves using coal gangue as a raw material face two major challenges: first, carbonaceous impurities and metal oxides such as iron and calcium in coal gangue interfere with the crystallization process, hindering crystal growth; second, silicon and aluminum elements in coal gangue exist as stable mineral phases, making efficient dissociation into active species difficult, resulting in synthesized zeolite molecular sieves with a crystallinity generally below 60%, significantly reducing their catalytic activity and adsorption performance. For example, the coal gangue-based SAPO-34 molecular sieve synthesized using existing methods exhibits a methanol conversion rate of less than 90% and a low-carbon olefin selectivity of less than 75% in the MTO reaction; the denitrification efficiency of SSZ-13 molecular sieve is 15%-20% lower than that of kaolin-based products. These problems severely limit the resource utilization of coal gangue in the field of zeolite molecular sieves, and also restrict the industrialization process of low-cost, high-performance zeolite molecular sieves. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves. Through the "acid extraction-alkali neutralization" activation process, active alumina species are pre-placed in the coal gangue, which significantly improves the crystallization efficiency and crystallinity.

[0006] This invention is achieved using the following technical solution: The method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Roast coal gangue to obtain roasted coal gangue; (2) The roasted coal gangue obtained in step (1) is mixed with acid and water and stirred at 65~95℃ for 1~5h. Then, an alkaline solution is added dropwise to adjust the pH to 7~10. The mixture is allowed to stand for aging for 0.5~4h. After filtration, washing and drying, activated coal gangue is obtained. (3) The activated coal gangue obtained in step (2) is mixed with at least one external source, template agent, solid seed crystal and water, and transferred to a high pressure vessel for crystallization. After crystallization, the mixture is cooled, filtered, washed, dried and calcined to obtain the zeolite molecular sieve. The external source is selected from silicon sources, phosphorus sources, or combinations thereof, depending on the type of the target zeolite molecular sieve.

[0007] The zeolite molecular sieve is SAPO-34, SSZ-13, or AlPO4-5 zeolite molecular sieve.

[0008] The roasting temperature in step (1) is 600~800℃ and the roasting time is 1~5h; the acid in step (2) is at least one of hydrochloric acid, sulfuric acid or nitric acid, preferably sulfuric acid; the alkaline solution is at least one of ammonia water, sodium hydroxide solution, potassium hydroxide solution, sodium aluminate solution, potassium aluminate solution, sodium carbonate solution or potassium carbonate solution, preferably sodium hydroxide; the mass ratio of roasted coal gangue, acid and water in step (2) is 1:(0.1~0.5):(4~8).

[0009] When the external source in step (3) is a silicon source, the silicon source is at least one of sodium silicate, potassium silicate, silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate or butyl orthosilicate, preferably silica sol; when the external source is a phosphorus source, the phosphorus source is at least one of orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate or diammonium hydrogen phosphate, preferably orthophosphoric acid.

[0010] The template agent mentioned in step (3) is selected according to the type of the target zeolite molecular sieve: When synthesizing SAPO-34 zeolite molecular sieve, the template agent is at least one of tetraethylammonium hydroxide, triethylamine, diethylamine, n-butylamine or isopropylamine, preferably tetraethylammonium hydroxide; When synthesizing SSZ-13 zeolite molecular sieve, the template agent is at least one of N,N,N-trimethyl-1-adamantane ammonium hydroxide, benzyltrimethylammonium or choline, preferably N,N,N-trimethyl-1-adamantane ammonium hydroxide; When synthesizing AlPO4-5 zeolite molecular sieves, the template agent is at least one of triethylamine, tetrapropylammonium hydroxide, tetramethylguanidine, cyclohexylamine, di-n-propylamine, piperidine, or hexamethylenediamine, preferably tetrapropylammonium hydroxide.

[0011] The solid seed crystals mentioned in step (3) are zeolite molecular sieves that are the same as or similar in structure to the target zeolite molecular sieve, and their crystallinity is ≥85%.

[0012] In step (3), the mass ratio of activated coal gangue, external source, template agent, solid seed crystal and water is 1: (0.05~1.0): (0.1~0.3): (0.01~0.15): (6~10), wherein the external source is calculated as oxide: silicon source is calculated as SiO2 and phosphorus source is calculated as P2O5.

[0013] In step (3), the crystallization temperature is 100~200℃ and the crystallization time is 24~72h; the calcination temperature is 450~700℃ and the calcination time is 1~5h.

[0014] The method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves further includes an ion exchange step after step (3) for preparing MTO catalyst.

[0015] The ion exchange is carried out using an ammonium salt, which is at least one of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium acetate, ammonium oxalate, or ammonium citrate, with ammonium chloride being preferred.

[0016] The working principle of this invention is as follows: A three-step process of roasting, acid extraction, and alkali neutralization is used to achieve efficient dissociation and purification of silicon and aluminum elements in coal gangue. First, roasting at 600-800℃ removes carbonaceous impurities from the coal gangue and transforms mineral phases such as kaolinite into more reactive metakaolinite. Subsequently, acid extraction (preferably with sulfuric acid) at 65-95℃ selectively removes metal oxide impurities such as iron and calcium from the coal gangue and dissociates stable aluminum-oxygen bonds into free Al. 3+ Finally, the pH was adjusted to 7-10 by adding alkaline solution dropwise to allow free Al to dissolve. 3+ With OH - The reaction generates active alumina species (such as AlO(OH) and Al(OH)3), which are uniformly loaded onto the surface of the coal gangue matrix to form "activated coal gangue", providing a highly active aluminum source for subsequent crystallization.

[0017] Based on the target zeolite molecular sieve type, the external sources (silicon / phosphorus source), template agents, and solid-phase seed crystals are precisely selected. For example, in the synthesis of SAPO-34, silica sol is used as the silicon source and orthophosphoric acid as the phosphorus source to form a Si-Al-P ternary system with the active alumina species in activated coal gangue. At the same time, SAPO-34 solid-phase seed crystals with a crystallinity of ≥85% are added, whose crystal structure can serve as "nuclei" to reduce the nucleation energy barrier of zeolite crystals. The template agent (such as tetraethylammonium hydroxide) induces the Si, Al, and P species to arrange themselves in an ordered manner according to the CHA topology through steric hindrance, promoting the directional growth of crystals.

[0018] During the high-pressure autoclave crystallization process at 100-200℃, the active alumina species in the activated coal gangue can directly react with exogenous Si / P species, avoiding the energy loss from the secondary dissociation of the silicon-aluminum source in traditional processes. Simultaneously, the presence of solid-phase seed crystals shortens the crystal growth cycle, and the spatial guiding effect of the template agent reduces impurity crystal formation. Finally, the template agent is removed by calcination at 450-700℃, forming a highly crystalline zeolite molecular sieve. The impurity removal step is optional and is used to further remove soluble impurities from the coal gangue, but the core activation step is acid extraction followed by alkali neutralization.

[0019] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention utilizes an "acid extraction-alkali neutralization" activation process to convert aluminum elements in coal gangue into active alumina species. Combined with the inductive effect of solid-phase seed crystals, the crystallinity of the synthesized SAPO-34, SSZ-13, and AlPO4-5 molecular sieves reaches 70%-76%, 72%-78%, and 70%-76%, respectively, which is more than 40% higher than the existing technology. The high-performance products exhibit superior application performance. For example, the SAPO-34-based MTO catalyst has a methanol conversion rate of ≥96% and a low-carbon olefin selectivity of ≥83%; the SSZ-13 molecular sieve maintains a denitrification efficiency of over 90% in the 200-400℃ range.

[0020] (2) The present invention can consume 0.8-1.2 tons of coal gangue for every 1 ton of zeolite molecular sieve synthesized. This not only solves the problem of land occupation and environmental pollution caused by coal gangue stockpiling, but also provides a high value-added path for solid waste resource utilization. The cost of raw materials can be reduced by 300-500 yuan per ton of product, with significant economic and environmental benefits.

[0021] (3) By adjusting the external source, template agent and seed crystal type, the present invention can realize the integrated synthesis of various zeolite molecular sieves such as SAPO-34, SSZ-13 and AlPO4-5 without changing the core equipment; at the same time, the process parameters (such as calcination temperature and crystallization time) can be flexibly adjusted according to actual needs to adapt to different scales of industrial production.

[0022] (4) Acid and alkali reagents in the process can be recycled through washing liquid, and the water resource utilization rate is increased to more than 80%; the roasting and crystallization process adopts closed equipment, with no harmful gas emissions, which meets the requirements of the national "dual carbon" strategy and green chemical development. Attached Figure Description

[0023] Figure 1 The XRD pattern of SAPO-34 synthesized in Example 1 of this invention; Figure 2 The XRD pattern of SAPO-34 synthesized in Comparative Example 1 of this invention; Figure 3 The XRD pattern of SSZ-13 synthesized in Example 6 of this invention; Figure 4 The XRD pattern of SSZ-13 synthesized in Comparative Example 4 of this invention; Figure 5 The XRD pattern of the MTO catalyst synthesized in Example 16 of this invention; Figure 6 The image shows the XRD pattern of the MTO catalyst synthesized in Comparative Example 10 of this invention. Detailed Implementation

[0024] To make the objectives and technical solutions of this invention clearer, the invention will be further described in detail below.

[0025] (1) Raw material specifications Coal gangue: SiO2: 45.2%; Al2O3: 47.3%; Shanxi Jinkun Shuozhou Kaolin Co., Ltd. SAPO-34 zeolite molecular sieve: KCAT-MTO-34, crystallinity 96%, Zhongke Catalysis New Technology (Dalian) Co., Ltd.; SSZ-13 zeolite molecular sieve: NZ-HS13-001, crystallinity 95%, Zhuoyue Environmental New Materials (Shanghai) Co., Ltd.; AlPO4-5 zeolite molecular sieve: AP5-00, crystallinity 90%, Zhuoyue Environmental New Materials (Shanghai) Co., Ltd.; Silica sol (SiO2 content 40%), sodium hydroxide, orthophosphoric acid (85%), tetraethylammonium hydroxide (TEAOH, 35%) and sulfuric acid, analytical grade reagents, were purchased from Sinopharm Group; N,N,N-trimethyl-1-adamantane ammonium hydroxide (25%) was purchased from Sigma-Aldrich Reagents.

[0026] (2) Analysis and testing The crystallinity of the zeolite molecular sieve was analyzed using a D / max-2200PC X-ray diffractometer manufactured by Rigaku Corporation, Japan. XRD measurements were performed using CuKα radiation at a scan rate of 2° / min and a scan range of 5–50°.

[0027] The catalytic performance of the prepared MTO catalyst for methanol-to-olefins reaction was evaluated in a fixed fluidized bed apparatus. Conversion and product distribution were analyzed by gas chromatography. The MTO reaction was carried out in a fixed fluidized bed at a temperature of 450 °C and a methanol weight hourly space velocity (WHSV) of 2 h⁻¹. -1 Nitrogen is used as the carrier gas.

[0028] Example 1 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) 1000g of coal gangue was roasted at 600℃ for 4h to obtain roasted coal gangue.

[0029] (2) Mix 500g of roasted coal gangue obtained in step (1), 250g of sulfuric acid and 2000g of water, and stir continuously at 65℃ for 5h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7.5, and then let it stand for 4h; finally, after filtration, washing and drying, activated coal gangue is obtained.

[0030] (3) Mix 100g of activated coal gangue obtained in step (2), 12.5g of silica sol, 64.9g of orthophosphoric acid, 28.6g of TEAOH, 1g of SAPO-34 molecular sieve, and 600g of water, and then transfer the mixture to an autoclave for crystallization (160℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry, and calcine (500℃, 5h) to obtain the in-situ crystallized high-crystallinity SAPO-34 zeolite molecular sieve C1. The XRD pattern of the synthesized SAPO-34 in Example 1 is shown in the figure. Figure 1 .

[0031] Example 2 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) 1000g of coal gangue was roasted at 650℃ for 3h to obtain roasted coal gangue.

[0032] (2) Mix 500g of roasted coal gangue obtained in step (1), 200g of sulfuric acid and 2500g of water, and stir continuously at 75°C for 4h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 8, and then let it stand for 4h; finally, after filtration, washing and drying, activated coal gangue is obtained.

[0033] (3) Mix 100g of activated coal gangue obtained in step (2), 17.5g of silica sol, 81.2g of orthophosphoric acid, 42.8g of TEAOH, 3g of SAPO-34 molecular sieve and 700g of water, and then transfer it to an autoclave for crystallization (170℃, 60h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (550℃, 4h) to obtain the in-situ crystallized high crystallinity SAPO-34 zeolite molecular sieve C2.

[0034] Example 3 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) 1000g of coal gangue was roasted at 700℃ for 2h to obtain roasted coal gangue.

[0035] (2) Mix 500g of roasted coal gangue obtained in step (1), 150g of sulfuric acid and 3000g of water, and stir continuously at 85℃ for 3h; then add 1mol / L sodium hydroxide solution to the above slurry system until the pH of the slurry system is 8.5, and then let it stand for 2h; finally, after filtration, washing and drying, activated coal gangue is obtained.

[0036] (3) Mix 100g of activated coal gangue obtained in step (2), 22.5g of silica sol, 97.4g of orthophosphoric acid, 57.1g of TEAOH, 5g of SAPO-34 molecular sieve and 800g of water, and then transfer it to an autoclave for crystallization (180℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (600℃, 3h) to obtain the in-situ crystallized high crystallinity SAPO-34 zeolite molecular sieve C3.

[0037] Example 4 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) 1000g of coal gangue was roasted at 750℃ for 1.5h to obtain roasted coal gangue.

[0038] (2) Mix 500g of roasted coal gangue obtained in step (1), 100g of sulfuric acid and 3500g of water, and stir continuously at 90℃ for 2h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 9, and then let it stand for aging for 1h; finally, after filtration, washing and drying, activated coal gangue is obtained.

[0039] (3) Mix 100g of activated coal gangue obtained in step (2), 27.5g of silica sol, 113.6g of orthophosphoric acid, 71.4g of TEAOH, 7g of SAPO-34 molecular sieve and 900g of water, and then transfer it to an autoclave for crystallization (190℃, 36h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (650℃, 2h) to obtain the in-situ crystallized high crystallinity SAPO-34 zeolite molecular sieve C4.

[0040] Example 5 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) 1000g of coal gangue was roasted at 800℃ for 1h to obtain roasted coal gangue.

[0041] (2) Mix 500g of roasted coal gangue obtained in step (1), 50g of sulfuric acid and 4000g of water, and stir continuously at 95℃ for 1h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 9.5, and then let it stand for aging for 0.5h; finally, after filtration, washing and drying, activated coal gangue is obtained.

[0042] (3) Mix 100g of activated coal gangue obtained in step (2), 32.5g of silica sol, 129.8g of orthophosphoric acid, 85.7g of TEAOH, 10g of SAPO-34 molecular sieve and 1000g of water, and then transfer it to an autoclave for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (700℃, 1h) to obtain the in-situ crystallized high crystallinity SAPO-34 zeolite molecular sieve C5.

[0043] Example 6 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0044] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (800℃, 1h) to obtain roasted coal gangue.

[0045] (3) Mix 300g of roasted coal gangue obtained in step (1), 30g of sulfuric acid and 1200g of water, and stir continuously at 65℃ for 5h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7, let it stand for 4h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0046] (4) Mix 100g of activated coal gangue obtained in step (3), 125g of silica sol, 40g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 5g of SSZ-13 zeolite molecular sieve, and 600g of water, and then transfer the mixture to an autoclave for crystallization (100℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry, and calcine (500℃, 5h) to obtain the in-situ crystallized SSZ-13 zeolite molecular sieve C6. The XRD pattern of the synthesized SSZ-13 in Example 6 is shown in [reference needed]. Figure 3 .

[0047] Example 7 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 150g of sulfuric acid and 5000g of water and stir at 92℃ for 1.5h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0048] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (750℃, 2h) to obtain roasted coal gangue.

[0049] (3) Mix 300g of roasted coal gangue obtained in step (1), 45g of sulfuric acid and 1500g of water, and stir continuously at 72℃ for 4h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7.5, let it stand for 3h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0050] (4) Mix 100g of activated coal gangue obtained in step (3), 150g of silica sol, 60g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 7g of SSZ-13 zeolite molecular sieve and 700g of water, and then transfer it to an autoclave for crystallization (115℃, 60h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (550℃, 4h) to obtain the in-situ crystallized SSZ-13 zeolite molecular sieve C7.

[0051] Example 8 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0052] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (700℃, 3h) to obtain roasted coal gangue.

[0053] (3) Mix 300g of roasted coal gangue obtained in step (1), 60g of sulfuric acid and 1800g of water, and stir continuously at 79°C for 3h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 8, let it stand for 2h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0054] (4) Mix 100g of activated coal gangue obtained in step (3), 175g of silica sol, 80g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 9g of SSZ-13 zeolite molecular sieve and 800g of water, and then transfer it to an autoclave for crystallization (130℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (600℃, 3h) to obtain the in-situ crystallized SSZ-13 zeolite molecular sieve C8.

[0055] Example 9 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 250g of sulfuric acid and 7000g of water and stir at 84℃ for 2.5h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0056] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (650℃, 4h) to obtain roasted coal gangue.

[0057] (3) Mix 300g of roasted coal gangue obtained in step (1), 75g of sulfuric acid and 2100g of water, and stir continuously at 86℃ for 2h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 8.5, let it stand for 1h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0058] (4) Mix 100g of activated coal gangue obtained in step (3), 200g of silica sol, 100g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 11g of SSZ-13 zeolite molecular sieve and 900g of water, and then transfer it to an autoclave for crystallization (145℃, 36h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (650℃, 2h) to obtain the in-situ crystallized SSZ-13 zeolite molecular sieve C9.

[0059] Example 10 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0060] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (600℃, 5h) to obtain roasted coal gangue.

[0061] (3) Mix 300g of roasted coal gangue obtained in step (1), 90g of sulfuric acid and 2400g of water, and stir continuously at 93℃ for 1h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 9, let it stand for aging for 0.5h, and obtain activated coal gangue after filtration, washing and drying.

[0062] (4) Mix 100g of activated coal gangue obtained in step (3), 225g of silica sol, 120g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 13g of SSZ-13 zeolite molecular sieve and 1000g of water, and then transfer it to an autoclave for crystallization (160℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (700℃, 1h) to obtain the in-situ crystallized SSZ-13 zeolite molecular sieve C10.

[0063] Example 11 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0064] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (800℃, 1h) to obtain roasted coal gangue.

[0065] (3) Mix 300g of roasted coal gangue obtained in step (1), 30g of sulfuric acid and 1200g of water, and stir continuously at 65℃ for 5h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7, let it stand for 4h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0066] (4) Mix 100g of activated coal gangue obtained in step (3), 89.3g of phosphoric acid, 28.6g of tetrapropylammonium hydroxide, 5g of AlPO4-5 zeolite molecular sieve and 600g of water, and then transfer it to an autoclave for crystallization (100℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (500℃, 5h) to obtain the in-situ crystallized AlPO4-5 zeolite molecular sieve C11.

[0067] Example 12 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 150g of sulfuric acid and 5000g of water and stir at 92℃ for 1.5h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0068] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (750℃, 2h) to obtain roasted coal gangue.

[0069] (3) Mix 300g of roasted coal gangue obtained in step (1), 45g of sulfuric acid and 1500g of water, and stir continuously at 72℃ for 4h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7.5, let it stand for 3h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0070] (4) Mix 100g of activated coal gangue obtained in step (3), 105.5g of phosphoric acid, 22.8g of tetrapropylammonium hydroxide, 7g of AlPO4-5 zeolite molecular sieve and 700g of water, and then transfer it to an autoclave for crystallization (125℃, 60h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (550℃, 4h) to obtain the in-situ crystallized AlPO4-5 zeolite molecular sieve C12.

[0071] Example 13 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0072] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (700℃, 3h) to obtain roasted coal gangue.

[0073] (3) Mix 300g of roasted coal gangue obtained in step (1), 60g of sulfuric acid and 1800g of water, and stir continuously at 79°C for 3h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 8, let it stand for 2h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0074] (4) Mix 100g of activated coal gangue obtained in step (3), 121.7g of phosphoric acid, 17.1g of tetrapropylammonium hydroxide, 9g of AlPO4-5 zeolite molecular sieve and 800g of water, and then transfer it to an autoclave for crystallization (150℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (600℃, 3h) to obtain the in-situ crystallized AlPO4-5 zeolite molecular sieve C13.

[0075] Example 14 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 250g of sulfuric acid and 7000g of water and stir at 84℃ for 2.5h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0076] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (650℃, 4h) to obtain roasted coal gangue.

[0077] (3) Mix 300g of roasted coal gangue obtained in step (1), 75g of sulfuric acid and 2100g of water, and stir continuously at 86℃ for 2h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 8.5, let it stand for 1h for aging, and then filter, wash and dry to obtain activated coal gangue.

[0078] (4) Mix 100g of activated coal gangue obtained in step (3), 137.9g ​​of phosphoric acid, 21.4g of tetrapropylammonium hydroxide, 11g of AlPO4-5 zeolite molecular sieve and 900g of water, and then transfer it to an autoclave for crystallization (175℃, 36h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (650℃, 2h) to obtain the in-situ crystallized AlPO4-5 zeolite molecular sieve C14.

[0079] Example 15 A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0080] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (600℃, 5h) to obtain roasted coal gangue.

[0081] (3) Mix 300g of roasted coal gangue obtained in step (1), 90g of sulfuric acid and 2400g of water, and stir continuously at 93℃ for 1h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 9, let it stand for aging for 0.5h, and obtain activated coal gangue after filtration, washing and drying.

[0082] (4) Mix 100g of activated coal gangue obtained in step (3), 162.3g of phosphoric acid, 25.7g of tetrapropylammonium hydroxide, 13g of AlPO4-5 zeolite molecular sieve and 1000g of water, and then transfer it to an autoclave for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (700℃, 1h) to obtain the in-situ crystallized AlPO4-5 zeolite molecular sieve C15.

[0083] Example 16 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 62.5g of silica sol and 1000g of water, and then spray dry and calcine (800℃, 1h) to obtain calcined coal gangue microspheres.

[0084] (3) Mix 300g of roasted coal gangue microspheres obtained in step (2), 30g of sulfuric acid and 1200g of water, and stir continuously at 65℃ for 5h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 7, let it stand for 4h for aging, and obtain activated coal gangue microspheres after filtration, washing and drying.

[0085] (4) Mix 100g of activated coal gangue microspheres obtained in step (3), 64.9g of phosphoric acid, 28.6g of tetraethylammonium hydroxide, 1g of SAPO-34 molecular sieve and 600g of water, and then transfer them to an autoclave for crystallization (160℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (500℃, 5h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0086] (5) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (4), 3.5g of ammonium chloride, and 280g of water, and performing ion exchange, the MTO catalyst C16 prepared by in-situ crystallization of solid waste coal gangue is obtained. The XRD pattern of the synthesized MTO catalyst in Example 16 is shown in [reference needed]. Figure 5 .

[0087] Example 17 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 150g of sulfuric acid and 5000g of water and stir at 92℃ for 1.5h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 87.5g of silica sol and 1250g of water, and then spray dry and calcine (750℃, 2h) to obtain calcined coal gangue microspheres.

[0088] (3) Mix 300g of roasted coal gangue microspheres obtained in step (2), 45g of sulfuric acid and 1500g of water, and stir continuously at 72℃ for 4h; then add 1mol / L sodium hydroxide solution to the above slurry system until the pH of the slurry system is 7.5, let it stand for 3h for aging, and obtain activated coal gangue microspheres after filtration, washing and drying.

[0089] (4) Mix 100g of activated coal gangue microspheres obtained in step (3), 81.2g of phosphoric acid, 42.8g of tetraethylammonium hydroxide, 3g of SAPO-34 molecular sieve and 700g of water, and then transfer them to an autoclave for crystallization (170℃, 60h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (550℃, 4h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0090] (5) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (4), 4.9g of ammonium chloride and 350g of water, and performing ion exchange, the MTO catalyst C17 prepared by in-situ crystallization of solid waste coal gangue is obtained.

[0091] Example 18 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 112.5g of silica sol and 1500g of water, and then spray dry and calcine (700℃, 3h) to obtain calcined coal gangue microspheres.

[0092] (3) Mix 300g of roasted coal gangue microspheres obtained in step (2), 60g of sulfuric acid and 1800g of water, and stir continuously at 79℃ for 3h; then add 1mol / L sodium hydroxide solution to the above slurry system until the pH of the slurry system is 8, let it stand for 2h for aging, and then filter, wash and dry to obtain activated coal gangue microspheres.

[0093] (4) Mix 100g of activated coal gangue microspheres obtained in step (3), 97.4g of phosphoric acid, 57.1g of tetraethylammonium hydroxide, 5g of SAPO-34 molecular sieve and 800g of water, and then transfer them to an autoclave for crystallization (180℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (600℃, 3h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0094] (5) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (4), 6.3g of ammonium chloride and 420g of water, and performing ion exchange, the MTO catalyst C18 prepared by in-situ crystallization of solid waste coal gangue is obtained.

[0095] Example 19 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 250g of sulfuric acid and 7000g of water and stir at 84℃ for 2.5h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 137.5g of silica sol and 1750g of water, and then spray dry and calcine (650℃, 4h) to obtain calcined coal gangue microspheres.

[0096] (3) Mix 300g of roasted coal gangue microspheres obtained in step (2), 75g of sulfuric acid and 2100g of water, and stir continuously at 86℃ for 2h; then add 1mol / L sodium hydroxide solution to the above slurry system until the pH of the slurry system is 8.5, let it stand for 1h for aging, and then filter, wash and dry to obtain activated coal gangue microspheres.

[0097] (4) Mix 100g of activated coal gangue microspheres obtained in step (3), 113.6g of phosphoric acid, 71.4g of tetraethylammonium hydroxide, 7g of SAPO-34 molecular sieve and 900g of water, and then transfer them to an autoclave for crystallization (190℃, 36h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (650℃, 2h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0098] (5) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (4), 7.7g of ammonium chloride and 490g of water, and performing ion exchange, the MTO catalyst C19 prepared by in-situ crystallization of solid waste coal gangue is obtained.

[0099] Example 20 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 162.5g of silica sol and 2000g of water, and then spray dry and calcine (600℃, 5h) to obtain calcined coal gangue microspheres.

[0100] (3) Mix 300g of roasted coal gangue microspheres obtained in step (2), 90g of sulfuric acid and 2400g of water, and stir continuously at 93℃ for 1h; then add sodium hydroxide solution with a concentration of 1mol / L to the above slurry system until the pH of the slurry system is 9, let it stand for aging for 0.5h, and obtain activated coal gangue microspheres after filtration, washing and drying.

[0101] (4) Mix 100g of activated coal gangue microspheres obtained in step (3), 129.8g of phosphoric acid, 85.7g of tetraethylammonium hydroxide, 9g of SAPO-34 molecular sieve and 1000g of water, and then transfer them to an autoclave for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and calcine (700℃, 1h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0102] (5) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (4), 9.1g of ammonium chloride and 560g of water, and performing ion exchange, the MTO catalyst C20 is prepared by in-situ crystallization of solid waste coal gangue.

[0103] Comparative Example 1 The synthesis method of zeolite molecular sieves includes the following steps: (1) 500g of coal gangue was roasted at 600℃ for 4h to obtain roasted coal gangue.

[0104] (2) Mix 100g of roasted coal gangue obtained in step (1), 12.5g of silica sol, 64.9g of orthophosphoric acid, 28.6g of TEAOH, and 600g of water, and then transfer the mixture to an autoclave for crystallization (160℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry, and calcine (500℃, 5h) to obtain the comparative in-situ crystallized SAPO-34 zeolite molecular sieve D1. The XRD pattern of SAPO-34 synthesized in Comparative Example 1 is shown in [reference needed]. Figure 2 .

[0105] Comparative Example 2 The synthesis method of zeolite molecular sieves includes the following steps: (1) 500g of coal gangue was roasted at 700℃ for 2h to obtain roasted coal gangue.

[0106] (2) Mix 100g of roasted coal gangue obtained in step (1), 22.5g of silica sol, 97.4g of phosphoric acid, 57.1g of TEAOH and 800g of water, and then transfer it to a high pressure vessel for crystallization (180℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and roast (600℃, 3h) to obtain comparative in-situ crystallized SAPO-34 zeolite molecular sieve D2.

[0107] Comparative Example 3 The synthesis method of zeolite molecular sieves includes the following steps: (1) 500g of coal gangue was roasted at 800℃ for 1h to obtain roasted coal gangue.

[0108] (2) Mix 100g of roasted coal gangue obtained in step (1), 32.5g of silica sol, 129.8g of phosphoric acid, 85.7g of TEAOH and 1000g of water, and then transfer it to a high pressure vessel for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and roast (700℃, 1h) to obtain comparative in-situ crystallized SAPO-34 zeolite molecular sieve D3.

[0109] Comparative Example 4 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0110] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (800℃, 1h) to obtain roasted coal gangue.

[0111] (3) Mix 100g of roasted coal gangue obtained in step (2), 125g of silica sol, 40g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 5g of SSZ-13 zeolite molecular sieve, and 600g of water, and then transfer the mixture to an autoclave for crystallization (100℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry, and calcine (500℃, 5h) to obtain comparative in-situ crystallized SSZ-13 zeolite molecular sieve D4. The XRD pattern of SSZ-13 synthesized in Comparative Example 4 is shown in [reference needed]. Figure 4 .

[0112] Comparative Example 5 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0113] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (700℃, 3h) to obtain roasted coal gangue.

[0114] (3) Mix 100g of roasted coal gangue obtained in step (2), 175g of silica sol, 80g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 9g of SSZ-13 zeolite molecular sieve and 800g of water, and then transfer it to an autoclave for crystallization (130℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and roast (600℃, 3h) to obtain comparative in-situ crystallized SSZ-13 zeolite molecular sieve D5.

[0115] Comparative Example 6 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0116] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (600℃, 5h) to obtain roasted coal gangue.

[0117] (3) Mix 100g of roasted coal gangue obtained in step (2), 225g of silica sol, 120g of N,N,N-trimethyl-1-adamantane ammonium hydroxide, 13g of SSZ-13 zeolite molecular sieve and 1000g of water, and then transfer it to an autoclave for crystallization (160℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and roast (700℃, 1h) to obtain comparative in-situ crystallized SSZ-13 zeolite molecular sieve D6.

[0118] Comparative Example 7 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0119] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (800℃, 1h) to obtain roasted coal gangue.

[0120] (3) Mix 100g of roasted coal gangue obtained in step (2), 89.3g of phosphoric acid, 28.6g of tetrapropylammonium hydroxide, 5g of AlPO4-5 zeolite molecular sieve and 600g of water, and then transfer it to an autoclave for crystallization (100℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry and roast (500℃, 5h) to obtain comparative in-situ crystallized AlPO4-5 zeolite molecular sieve D7.

[0121] Comparative Example 8 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0122] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (700℃, 3h) to obtain roasted coal gangue.

[0123] (3) Mix 100g of roasted coal gangue obtained in step (2), 121.7g of orthophosphoric acid, 57.1g of tetrapropylammonium hydroxide, 9g of AlPO4-5 zeolite molecular sieve and 800g of water, and then transfer it to an autoclave for crystallization (150℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and roast (600℃, 3h) to obtain comparative in-situ crystallized AlPO4-5 zeolite molecular sieve D8.

[0124] Comparative Example 9 The synthesis method of zeolite molecular sieves includes the following steps: (1) Mix 1000g of coal gangue, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain cleaned coal gangue.

[0125] (2) Roast 500g of the cleaned coal gangue obtained in step (1) (600℃, 5h) to obtain roasted coal gangue.

[0126] (3) Mix 100g of roasted coal gangue obtained in step (2), 162.3g of phosphoric acid, 85.7g of tetrapropylammonium hydroxide, 13g of AlPO4-5 zeolite molecular sieve and 1000g of water, and then transfer it to an autoclave for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and roast (700℃, 1h) to obtain comparative in-situ crystallized AlPO4-5 zeolite molecular sieve D9.

[0127] Comparative Example 10 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 100g of sulfuric acid and 4000g of water and stir at 95℃ for 1h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 62.5g of silica sol and 1000g of water, and then spray dry and calcine (800℃, 1h) to obtain calcined coal gangue microspheres.

[0128] (3) Mix 100g of roasted coal gangue microspheres obtained in step (2), 64.9g of phosphoric acid, 28.6g of tetraethylammonium hydroxide, 1g of SAPO-34 molecular sieve and 600g of water, and then transfer them to an autoclave for crystallization (160℃, 72h). After crystallization, cool to room temperature, then filter, wash, dry and roast (500℃, 5h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0129] (4) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (3), 3.5g of ammonium chloride, and 280g of water, and performing ion exchange, the MTO catalyst D10 prepared by in-situ crystallization of comparative solid waste coal gangue was obtained. The XRD pattern of the MTO catalyst synthesized in Comparative Example 10 is shown in [reference needed]. Figure 6 .

[0130] Comparative Example 11 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 200g of sulfuric acid and 6000g of water and stir at 88℃ for 2h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 112.5g of silica sol and 1500g of water, and then spray dry and calcine (700℃, 3h) to obtain calcined coal gangue microspheres.

[0131] (3) Mix 100g of roasted coal gangue microspheres obtained in step (2), 97.4g of phosphoric acid, 57.1g of tetraethylammonium hydroxide, 5g of SAPO-34 molecular sieve and 800g of water, and then transfer them to an autoclave for crystallization (180℃, 48h). After crystallization, cool to room temperature, then filter, wash, dry and roast (600℃, 3h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0132] (4) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (3), 6.3g of ammonium chloride and 420g of water, and performing ion exchange, the MTO catalyst D11 prepared by in-situ crystallization of solid waste coal gangue was obtained.

[0133] Comparative Example 12 The synthesis method of MTO catalyst includes the following steps: (1) Mix 1000g of coal gangue powder, 300g of sulfuric acid and 8000g of water and stir at 80℃ for 3h to remove impurities. Then filter, wash and dry to obtain impurity-removed coal gangue powder. (2) Mix 500g of the cleaned coal gangue powder obtained in step (1), 162.5g of silica sol and 2000g of water, and then spray dry and calcine (600℃, 5h) to obtain calcined coal gangue microspheres.

[0134] (3) Mix 100g of roasted coal gangue microspheres obtained in step (2), 129.8g of phosphoric acid, 85.7g of tetraethylammonium hydroxide, 9g of SAPO-34 molecular sieve and 1000g of water, and then transfer them to an autoclave for crystallization (200℃, 24h). After crystallization, cool to room temperature, then filter, wash, dry and roast (700℃, 1h) to obtain SAPO-34 zeolite molecular sieve crystallized microspheres.

[0135] (4) After mixing 70g of SAPO-34 zeolite molecular sieve crystallized microspheres obtained in step (3), 9.1g of ammonium chloride and 560g of water, and performing ion exchange, the MTO catalyst D12 prepared by in-situ crystallization of solid waste coal gangue was obtained.

[0136] The crystallinity of the products obtained in Examples 1-20 is shown in Table 1.

[0137] The crystallinity of the products obtained in Comparative Examples 1-12 is shown in Table 2.

[0138] The reaction performance of the MTO catalysts prepared in Example 16 and Comparative Example 10 is shown in Table 3.

[0139] Table 1: Crystallinity of the products obtained in Examples 1-20

[0140] Table 2: Crystallinity of the products obtained in Comparative Examples 1-12

[0141] As shown in Tables 1-2, compared with existing in-situ crystallization synthesis methods, the in-situ crystallized zeolite molecular sieves synthesized by the method of the present invention exhibit significantly higher crystallinity. This indicates that the method of the present invention can significantly improve the crystallinity of molecular sieves synthesized from solid waste coal gangue in situ, thereby endowing the synthesized in-situ crystallized zeolite molecular sieves with excellent application performance. Compared with existing in-situ crystallization methods, the in-situ crystallized MTO catalyst prepared by the method of the present invention exhibits significantly higher crystallinity, indicating that the method of the present invention can significantly improve the crystallinity of molecular sieves prepared from solid waste coal gangue in situ.

[0142] Table 3: Reaction performance of the MTO catalysts prepared in Example 16 and Comparative Example 10

[0143] As shown in Table 3, compared with the existing in-situ crystallization method for preparing MTO catalysts, the in-situ crystallized MTO catalyst prepared by the method of the present invention has superior catalytic performance for methanol-to-olefins reaction, with its conversion rate and ethylene and propylene yields being much higher than the former.

Claims

1. A method for in-situ crystallization of solid waste coal gangue to synthesize zeolite molecular sieves, characterized in that, Includes the following steps: (1) Roast coal gangue to obtain roasted coal gangue; (2) The roasted coal gangue obtained in step (1) is mixed with acid and water and stirred at 65~95℃ for 1~5h. Then, an alkaline solution is added dropwise to adjust the pH to 7~10. The mixture is allowed to stand for aging for 0.5~4h. After filtration, washing and drying, activated coal gangue is obtained. (3) The activated coal gangue obtained in step (2) is mixed with at least one external source, template agent, solid seed crystal and water, and transferred to a high pressure vessel for crystallization. After crystallization, the mixture is cooled, filtered, washed, dried and calcined to obtain the zeolite molecular sieve. The external source is selected from silicon sources, phosphorus sources, or combinations thereof, depending on the type of the target zeolite molecular sieve.

2. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, The zeolite molecular sieve is SAPO-34, SSZ-13, or AlPO4-5 zeolite molecular sieve.

3. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, The roasting temperature in step (1) is 600~800℃ and the roasting time is 1~5h; the acid in step (2) is at least one of hydrochloric acid, sulfuric acid or nitric acid; the alkaline solution is at least one of ammonia water, sodium hydroxide solution, potassium hydroxide solution, sodium aluminate solution, potassium aluminate solution, sodium carbonate solution or potassium carbonate solution; the mass ratio of roasted coal gangue, acid and water in step (2) is 1:(0.1~0.5):(4~8).

4. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, When the external source in step (3) is a silicon source, the silicon source is at least one of sodium silicate, potassium silicate, silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate or butyl orthosilicate; when the external source is a phosphorus source, the phosphorus source is at least one of orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate or diammonium hydrogen phosphate.

5. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, The template agent mentioned in step (3) is selected according to the type of the target zeolite molecular sieve: When synthesizing SAPO-34 zeolite molecular sieve, the template agent is at least one of tetraethylammonium hydroxide, triethylamine, diethylamine, n-butylamine, or isopropylamine; When synthesizing SSZ-13 zeolite molecular sieve, the template agent is at least one of N,N,N-trimethyl-1-adamantane ammonium hydroxide, benzyltrimethylammonium or choline; When synthesizing AlPO4-5 zeolite molecular sieves, the template agent is at least one of triethylamine, tetrapropylammonium hydroxide, tetramethylguanidine, cyclohexylamine, di-n-propylamine, piperidine, or hexamethylenediamine.

6. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, The solid seed crystals mentioned in step (3) are zeolite molecular sieves that are the same as or similar in structure to the target zeolite molecular sieve, and their crystallinity is ≥85%.

7. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, In step (3), the mass ratio of activated coal gangue, external source, template agent, solid seed crystal and water is 1: (0.05~1.0): (0.1~0.3): (0.01~0.15): (6~10), wherein the external source is calculated as oxide: silicon source is calculated as SiO2 and phosphorus source is calculated as P2O5.

8. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, In step (3), the crystallization temperature is 100~200℃ and the crystallization time is 24~72h; the calcination temperature is 450~700℃ and the calcination time is 1~5h.

9. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 1, characterized in that, It also includes an ion exchange step after step (3) for preparing the MTO catalyst.

10. The method for in-situ crystallization synthesis of zeolite molecular sieves from solid waste coal gangue according to claim 9, characterized in that, The ion exchange is carried out using an ammonium salt, which is at least one of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium acetate, ammonium oxalate, or ammonium citrate.

Images