阅读说明：本技术 一种废弃硅磷铝分子筛为原料合成sapo-34分子筛的方法 (Method for synthesizing SAPO-34 molecular sieve by using waste silicoaluminophosphate molecular sieve as raw material ) 是由 季超 臧甲忠 于海斌 刘冠锋 李滨 洪鲁伟 宋万仓 洪美花 石芳 于 2021-08-06 设计创作，主要内容包括：本发明公开了一种废弃硅磷铝分子筛为原料合成SAPO-34分子筛的方法,该方法利用废弃硅铝分子筛,根据合成SAPO-34分子筛摩尔比调整上述合成液中的硅和铝的量可以合成出无杂晶的SAPO-34分子筛。本发明方法采用废弃的硅铝分子筛代替昂贵的工业原料制备分子筛,扩大了原料来源,降低了分子筛的制备成本和废弃分子筛的处理成本,并减少了由此造成的环境污染。(The invention discloses a method for synthesizing an SAPO-34 molecular sieve by using a waste silicoaluminophosphate molecular sieve as a raw material, which can synthesize the SAPO-34 molecular sieve without mixed crystals by adjusting the amount of silicon and aluminum in a synthetic liquid according to the molar ratio of the synthesized SAPO-34 molecular sieve by using the waste silicoaluminophosphate molecular sieve. The method of the invention adopts the waste silicon-aluminum molecular sieve to replace expensive industrial raw materials to prepare the molecular sieve, enlarges the raw material sources, reduces the preparation cost of the molecular sieve and the treatment cost of the waste molecular sieve, and reduces the environmental pollution caused by the preparation cost.)

1. A method for synthesizing SAPO-34 molecular sieve by taking waste silicoaluminophosphate molecular sieves as raw materials comprises the following steps:

1) uniformly mixing the waste silicon-phosphorus-aluminum molecular sieve with an acidic compound solution, wherein the mass ratio of the waste silicon-phosphorus-aluminum molecular sieve to the acidic compound solution is 1 (5-50), and the concentration of the acidic compound solution is 0.1-10 mol/L;

2) reacting the mixture prepared in the step 1) at 30-110 ℃ for 0.5-10 h, filtering to obtain an acidic reaction solution and insoluble substances, and washing and drying the insoluble substances;

3) uniformly mixing the dried insoluble substance obtained in the step 2) with an alkaline compound solution, wherein the mass ratio of the insoluble substance to the alkaline compound is 1 (5-50), and the concentration of the alkaline compound solution is 0.1-10 mol/L;

4) carrying out hydrothermal treatment on the mixture obtained in the step at the temperature of 30-110 ℃ for 2-10 h to obtain an alkaline reaction solution;

5) reacting said acid withMixing the reaction solution and the alkaline reaction solution to obtain a synthetic solution, and rapidly stirring the synthetic solution according to the molar ratio n (Al) of the synthesized SAPO-34 molecular sieve₂O₃)∶n(P₂O₅)∶n(SiO₂) N (template agent R) n (H)₂And (3) further adjusting the amount of silicon and aluminum in the synthetic liquid when O) is 1: 0.8-1.5: 0.1-1: 2-3.5: 50-200, quickly stirring for 1-10 h, transferring the slurry into a reaction kettle after the slurry is uniformly mixed, carrying out hydrothermal synthesis for 2-60 h at 90-200 ℃, cooling the reaction kettle, carrying out solid-liquid separation, washing and drying to obtain the SAPO-34 molecular sieve powder.

2. The method for synthesizing the SAPO-34 molecular sieve by using the waste silicoaluminophosphate molecular sieve as the raw material as claimed in claim 1, wherein the waste silicoaluminophosphate molecular sieve is at least one of waste SAPO-5, SAPO-34 and SAPO-37 molecular sieves.

3. The method for synthesizing the SAPO-34 molecular sieve by using the waste silicoaluminophosphate molecular sieve as the raw material as claimed in claim 1, wherein the acidic compound solution is a phosphoric acid solution; the alkaline compound solution is at least one alkali solution of triethylamine, tetraethyl ammonium hydroxide and morpholine.

4. The method for synthesizing the SAPO-34 molecular sieve by using the waste silicoaluminophosphate molecular sieve as the raw material as claimed in claim 1, wherein the aluminum source is at least one of a waste silicoaluminophosphate-containing molecular sieve or pseudo-boehmite; the phosphorus source is phosphoric acid; the silicon source is at least one of a waste molecular sieve containing silicon, phosphorus and aluminum or silica sol; the template agent R is at least one of triethylamine, tetraethyl ammonium hydroxide or morpholine.

5. The method for synthesizing the SAPO-34 molecular sieve by using the waste silicoaluminophosphate molecular sieve as the raw material according to claim 1, wherein when the acidic reaction solution and the alkaline reaction solution are mixed, the alkaline reaction solution is used as a base solution, and the acidic reaction solution is added for mixing; or adding an alkaline reaction solution into the acidic reaction solution as a base solution and mixing; or the alkaline reaction solution and the acidic reaction solution are mixed in parallel.

Technical Field

The invention belongs to the field of synthesis of molecular sieves, and relates to a method for synthesizing an SAPO-34 molecular sieve by using a waste silicoaluminophosphate molecular sieve as a raw material.

Background

In 1984, United states Union carbide (UCC) developed a series of products consisting of PO₂ ⁺、AlO₂ ^-And SiO₂Tetrahedra constitute a silicoaluminophosphate molecular sieve (SAPO-n) with a three-dimensional open framework structure (USP4,440,871). The synthesis method of the SAPO-34 molecular sieve reported at present generally comprises the steps of mixing a silicon source, an aluminum source, a template agent and water, then putting the mixture into a reaction kettle for high-temperature crystallization, obtaining a sample after crystallization, and then drying and roasting the sample to obtain the SAPO-34 molecular sieve.

In the field of petrochemical industry, silicon-phosphorus-aluminum molecular sieves are widely used, but the catalytic capability of the molecular sieves is reduced after the molecular sieves are used for a period of time, the molecular sieves are generally subjected to landfill treatment, but the components of the molecular sieves are basically not changed, and the molecular sieves are rich in P2O5 and SiO₂And Al₂O₃The molecular sieve is not used, which not only causes environmental pollution, but also wastes resources.

In addition, in the actual production, the generation of catalysts which do not meet the product standards due to factors such as unstable raw material sources, production processes, emergencies in the production and the like is inevitable, such as the crystalline phase, morphology, particle size distribution, wear index, density, evaluation performance and the like do not meet the standards, the catalysts which do not meet the product indexes cannot be directly applied to industrial devices, and if the catalysts are directly discarded, not only is the environment pollution caused, but also the production cost of the products is increased.

At present, various methods for industrially producing molecular sieves are available, and in the preparation process, inorganic or organic silicon sources, aluminum sources and other industrial raw materials are generally adopted, so that the raw materials are limited in source and expensive in cost.

Disclosure of Invention

Aiming at the defects of the prior art, the invention adopts the waste silicon-phosphorus-aluminum molecular sieve to replace expensive industrial raw materials to prepare the molecular sieve, thereby enlarging the raw material source, reducing the preparation cost of the molecular sieve and the treatment cost of the waste molecular sieve and reducing the environmental pollution caused by the preparation cost.

The purpose of the invention can be realized by the following technical scheme:

the invention provides a method for synthesizing an SAPO-34 molecular sieve by taking a waste silicoaluminophosphate molecular sieve as a raw material, which can synthesize the SAPO-34 molecular sieve without mixed crystals by utilizing the waste silicoaluminophosphate molecular sieve and adjusting the amount of silicon and aluminum in the synthetic liquid according to the molar ratio of the synthesized SAPO-34 molecular sieve. The method specifically comprises the following steps:

(1) uniformly mixing the waste silicon-phosphorus-aluminum molecular sieve with an acidic compound solution, wherein the mass ratio of the waste silicon-phosphorus-aluminum molecular sieve to the acidic compound solution is 1 (5-50), and the concentration of the acidic compound solution is 0.1-10 mol/L;

(2) reacting the mixture prepared in the first step at 30-110 ℃ for 0.5-10 h, filtering to obtain an acidic reaction solution and insoluble substances, and washing and drying the insoluble substances;

(3) and (3) uniformly mixing the insoluble substance prepared in the second step with an alkaline compound solution, wherein the mass ratio of the insoluble substance to the alkaline compound is 1 (5-50), and the concentration of the alkaline compound solution is 0.1-10 mol/L.

(4) Carrying out hydrothermal treatment on the mixture prepared in the third step at the temperature of 30-110 ℃ for 2-10 h to obtain an alkaline reaction solution;

(5) mixing the acidic reaction solution and the alkaline reaction solution, and rapidly stirring the synthetic solution according to the mole ratio n (Al) of the synthesized SAPO-34 molecular sieve₂O₃)∶n(P₂O₅)∶n(SiO₂) N (template agent R) n (H)₂And (3) further adjusting the amount of silicon and aluminum in the synthetic liquid when O) is 1: 0.8-1.5: 0.1-1: 2-3.5: 50-200, quickly stirring for 1-10 h, transferring the slurry into a reaction kettle after the slurry is uniformly mixed, carrying out hydrothermal synthesis for 2-60 h at 90-200 ℃, cooling the reaction kettle, carrying out solid-liquid separation, washing and drying to obtain the SAPO-34 molecular sieve powder.

In the method for synthesizing the SAPO-34 molecular sieve by taking the waste silicoaluminophosphate molecular sieve as the raw material, the used waste silicoaluminophosphate molecular sieve preferably comprises at least one of waste SAPO-5 molecular sieves, waste SAPO-34 molecular sieves and waste SAPO-37 molecular sieves;

in the method for synthesizing the SAPO-34 molecular sieve by taking the waste silicoaluminophosphate molecular sieve as a raw material, the acidic compound solution for dissolving the waste silicoaluminophosphate molecular sieve is preferably a phosphoric acid solution; the alkaline compound solution is at least one alkali solution of triethylamine, tetraethylammonium hydroxide and morpholine which are used as template agents R.

Preferably, the aluminum source is at least one of a waste silicoaluminophosphate-containing molecular sieve or pseudo-boehmite; the phosphorus source is from phosphoric acid; the silicon source is at least one of a waste molecular sieve containing silicon, phosphorus and aluminum or silica sol; the template agent is at least one of triethylamine, tetraethyl ammonium hydroxide or morpholine.

When the acidic reaction solution and the alkaline reaction solution in the step (5) are mixed, the alkaline reaction solution is used as a base solution, and the acidic reaction solution is added and mixed; or adding an alkaline reaction solution into the acidic reaction solution as a base solution and mixing; or the alkaline reaction solution and the acidic reaction solution are mixed in parallel.

Compared with the prior art, the invention has the following characteristics.

(1) The method solves the problems of the reutilization of the silicon-phosphorus-aluminum molecular sieve which contains mixed crystals, has appearance, particle size distribution, abrasion index, density, evaluation performance and the like and does not meet the product standard, and only can be used as solid waste for treatment if the silicon-phosphorus-aluminum molecular sieve is not recycled.

(2) The method recycles the waste silicon-phosphorus-aluminum molecular sieve catalyst, greatly improves the utilization efficiency, and greatly improves the product yield in the synthesis of the molecular sieve.

The synthesis method is simple, raw material sources are enlarged, the preparation cost of the molecular sieve and the treatment cost of the waste molecular sieve are reduced, and the environmental pollution caused by the preparation cost and the treatment cost is reduced.

Drawings

Fig. 1 is an X-ray diffraction (XRD) pattern of the synthesized product according to example 1.

Figure 2 is an X-ray diffraction (XRD) pattern of the product synthesized according to example 2.

Figure 3 is an X-ray diffraction (XRD) pattern of the synthesized product according to example 3.

Fig. 4 is an SEM image of the synthesized product according to example 3.

Detailed Description

The technical solution of the present invention is further described with reference to the following specific examples.

Example 1

Adding 5g of phosphoric acid (85%) into 55g of water to prepare a solution, then adding 2g of waste silicoaluminophosphate molecular sieve SAPO-37 molecular sieve, stirring at 80 ℃ for 5 hours, filtering to obtain an acidic reaction solution A and insoluble substances, and washing and drying the insoluble substances; uniformly mixing the insoluble substances with triethylamine solution, and carrying out hydrothermal treatment on the mixture at the temperature of 80 ℃ for 5 hours to obtain alkaline reaction liquid B; mixing the acidic reaction solution and the alkaline reaction solution, and rapidly stirring the synthetic solution according to the mole ratio n (Al) of the synthesized SAPO-34 molecular sieve₂O₃)∶n(P₂O₅)∶n(SiO₂) N (template agent R) n (H)₂And O) further adjusting the amount of silicon and aluminum in the synthetic solution to 1: 3.5: 60, quickly stirring for 3h, transferring the slurry into a reaction kettle after the slurry is uniformly mixed, carrying out hydrothermal synthesis for 30h at 160 ℃, cooling the reaction kettle, carrying out solid-liquid separation, washing and drying to obtain molecular sieve powder. The XRD pattern of the sample is shown in FIG. 1.

Example 2

Adding 5g of phosphoric acid (85%) into 55g of water to prepare a solution, then adding 1g of waste silicoaluminophosphate molecular sieve SAPO-5 molecular sieve, stirring at 60 ℃ for 5 hours, filtering to obtain an acidic reaction solution A and insoluble substances, and washing and drying the insoluble substances; uniformly mixing the insoluble substances with a morpholine solution, and carrying out hydrothermal treatment on the mixture at 60 ℃ for 5 hours to obtain an alkaline reaction solution B; mixing the acidic reaction solution and the alkaline reaction solution, and rapidly stirring the synthetic solution according to the mol n (Al) of the synthesized SAPO-34 molecular sieve₂O₃)∶n(P₂O₅)∶n(SiO₂) N (template agent R) n (H)₂Further adjusting the amount of silicon and aluminum in the synthetic solution to 1: 1.1: 0.4: 2.09: 100, rapidly stirring for 3h, transferring the slurry into a reaction kettle for hydrothermal synthesis for 48h at 200 ℃ after the slurry is uniformly mixed, cooling and reactingAnd (3) putting the mixture into a kettle, performing solid-liquid separation, washing and drying to obtain molecular sieve powder. The XRD pattern of the sample is shown in FIG. 2.

Example 3

Adding 5g of phosphoric acid (85%) into 55g of water to prepare a solution, then adding 1g of waste silicoaluminophosphate molecular sieve SAPO-34 molecular sieve, stirring at 40 ℃ for 5 hours, filtering to obtain an acidic reaction solution A and insoluble substances, and washing and drying the insoluble substances; uniformly mixing the insoluble substances with a tetraethylammonium hydroxide solution, and carrying out hydrothermal treatment on the mixture at 40 ℃ for 5 hours to obtain an alkaline reaction solution B; mixing the acidic reaction solution and the alkaline reaction solution, and rapidly stirring the synthetic solution according to the mole ratio n (Al) of the synthesized SAPO-34 molecular sieve₂O₃)∶n(P₂O₅)∶n(SiO₂) N (template agent R) n (H)₂And O) further adjusting the amount of silicon and aluminum in the synthetic solution to 1: 0.6: 2: 200, quickly stirring for 3h, transferring the slurry into a reaction kettle after the slurry is uniformly mixed, carrying out hydrothermal synthesis for 36h at 185 ℃, cooling the reaction kettle, carrying out solid-liquid separation, washing and drying to obtain molecular sieve powder. The XRD pattern of the sample is shown in FIG. 3; the SEM image of the synthesized sample is shown in FIG. 4.