WO2019241959A1

WO2019241959A1 - Method for recycling low-silicon x molecular sieve synthesis mother liquid

Info

Publication number: WO2019241959A1
Application number: PCT/CN2018/092187
Authority: WO
Inventors: 白长敏; 徐云鹏; 刘中民; 刘广业; 袁丹华
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2018-06-21
Filing date: 2018-06-21
Publication date: 2019-12-26

Abstract

A method for fully recycling a low-silicon X molecular sieve synthesis mother liquid, comprising in a molecular sieve preparation process, separating a product from a mother liquid, and then complementally adding an aluminum source, a potassium source, and a sodium source in the mother liquid and enabling recycling. According to the method, a mother liquid generated in low-silicon molecular sieve synthesis is recycled, so that the raw material costs are fully saved and the economic significance is achieved; in a mother liquid recycling process, no synthesis waste liquid is discharged, so that it is environment-friendly, the costs for waste liquid treatment are also saved, and every time the mother liquid is recycled, both economic and environment-protection significance are achieved.

Description

Recycling method for low silicon X molecular sieve synthesis mother liquor

Technical field

The present application relates to a method for recycling mother liquor of low silicon X molecular sieve synthesis, and belongs to the fields of inorganic chemistry and material chemistry.

Background technique

Low-silicon X molecular sieves have a wide range of applications in the field of PSA oxygen production. At the same time, they are also widely used as adsorbents in petrochemical, pharmaceutical, agricultural, construction, automotive and other industries. soften. Laboratory methods for low-silicon molecular sieves usually include hydrothermal synthesis and solid-phase synthesis. Hydrothermal synthesis has the characteristics of uniform mass and heat transfer. It is easy to obtain low-silicon molecular sieves with high purity phases, and both the adsorption capacity and the ion exchange capacity It is relatively high, so hydrothermal synthesis has more application value and can be widely used in large-scale production. However, the yield of the low-silicon molecular sieve obtained by the hydrothermal synthesis method is relatively low. Based on the total input amount, the product yield is between 10 and 13%. A large amount of waste liquid is produced during the production process, that is, the mother liquid. The mother liquid contains Unused components such as Na ₂ O, K ₂ O, Al ₂ O ₃ , SiO ₂ and a large amount of water, if the mother liquor is directly discharged, it will inevitably cause the loss of raw materials and environmental pollution. Therefore, how to effectively use the mother liquor is the synthesis of molecular sieve Key and difficult points in industry.

CN1406868A discloses a method for hydrothermal synthesis of low-silicon molecular sieves. The waste slag or mother liquor of a catalyst plant is used as part of the raw material for the synthesis of low-silicon molecular sieves. However, there is also a problem that a large amount of waste liquid is generated during the synthesis.

CN104174356A discloses a method for preparing a low-silicon molecular sieve, but a guide agent needs to be prepared during the synthesis process. In the mentioned mother liquor utilization scheme, it is necessary to collect and store the mother liquor and concentrate the mother liquor before processing. In the production process, one side is required. Adding fresh deionized water, while evaporating the moisture in the mother liquor, there is a problem that many processes require equipment, multiple energy consumption, and large production processes.

The invention pays attention to its own recycling. The mother liquor obtained by synthesizing low-silicon molecular sieves from fresh raw materials is directly used in the next synthesis without any treatment. The mother liquor no longer emits or needs to be stored during the recycling process. It is necessary to add fresh deionized water, and it is not necessary to prepare a directing agent, so it has both economic and environmental significance.

Summary of the Invention

According to one aspect of the present application, a method for recycling a low-silicon X molecular sieve synthesis mother liquor is provided, which is characterized in that the method includes the following steps:

1) Mixing aluminum source, sodium source, potassium source and water to obtain solution A0; mixing silicon source and water to obtain solution B0; adding B0 to A0, and aging and crystallizing the resulting mixture C0 to obtain low silicon X molecular sieve and mother liquor (the serial number "0" means that all ingredients are used in the formula without adding mother liquor ingredients);

2) Quantitative detection of components in the mother liquor by ion chromatography external standard method;

3) According to the detection result of step 2), aluminum source, sodium source, and potassium source are added to the mother liquor after quantitative detection to obtain a mixture An; a silicon source is mixed with water to obtain a solution Bn, and Bn is added to An. After the mixture Cn is aged and crystallized, a low-silicon X molecular sieve and a mother liquor are separated;

4) Repeat steps 2) to 3) repeatedly to realize the recycling of mother liquor in the synthesis of low-silicon X molecular sieve.

In the method of the present invention, the mother liquor is reused by adding raw materials necessary for the production of molecular sieve products to the mother liquor. By recycling all the mother liquor, the production cost is greatly reduced on the one hand, and the problem of waste liquid discharge is also solved on the other. .

Preferably, in the mixture C0 of step 1), the molar ratio of the sodium source, potassium source, aluminum source, silicon source, and water is:

Na ₂ O (2.0 ～ 6.0): K ₂ O (1.0 ～ 4.0): Al ₂ O ₃ (1.0 ～ 2.5): SiO ₂ (0.5 ～ 2.0): H ₂ O (80 ～ 150);

Wherein, the number of moles of the sodium source is calculated as the number of moles of Na ₂ O; the number of moles of the potassium source is calculated as the number of moles of K ₂ O; the number of moles of the aluminum source is calculated as the number of moles of Al ₂ O ₃ ; The number of moles of the silicon source is calculated as the number of moles of SiO ₂ ; the number of moles of the water is calculated as the number of moles of H ₂ O.

Preferably, in the mixture Cn of step 3), the molar ratio of the sodium source, potassium source, aluminum source, silicon source, and water is:

Preferably, the aging in step 1) and step 3) is aging at 55 ° C to 70 ° C for 6 to 10 hours.

Preferably, the crystallization in step 1) and step 3) is crystallization at 100 ° C to 110 ° C for 5 to 9 hours.

Preferably, the ion chromatography external standard method uses methanesulfonic acid as the eluent, and detects the ion concentration in the mother liquid based on the response relationship between the ion conductivity peak area and the ion concentration, and converts the ion concentration into the mother liquid. Mass fraction of each ingredient.

Preferably, the eluent is 26 mmol / L methanesulfonic acid.

Preferably, the sodium source is selected from at least one of sodium sulfate, sodium nitrate, and sodium hydroxide;

The potassium source is selected from at least one of potassium sulfate, potassium nitrate, and potassium hydroxide;

The silicon source is selected from at least one of silica sol, sodium silicate, and potassium silicate;

The aluminum source is selected from at least one of pseudo-boehmite, alumina, sodium aluminate, potassium aluminum sulfate, and potassium aluminate.

Preferably, the CO ₂ adsorption capacity of the low-silicon X molecular sieve is higher than 100 cm ³ / g at a temperature of 25 ° C. and a CO ₂ gas pressure of 250 mmHg.

Preferably, at a temperature of 25 ° C. and a CO ₂ pressure of 250 mmHg, the low silicon X molecular sieve adsorbs CO _{2 in} an amount of 100 cm ³ / g to 120 cm ³ / g.

The beneficial effects that this application can produce include:

1) The mother liquor produced by the synthesis of low-silicon molecular sieve has been recycled, which can fully save the cost of raw materials and has economic significance;

2) In the mother liquor recycling process, there is no need to add new deionized water, no storage and discharge of synthetic waste liquid, and it is environmentally friendly, which saves the cost of deionized water and equipment, and saves the cost of waste liquid treatment. Increasing the use of mother liquor once again has both economic and environmental significance.

3) The method of hydrothermal synthesis of low-silicon molecular sieves has the characteristics of uniform heat and mass transfer, easy to obtain high-purity phase products and good adsorption properties, and is suitable for large-scale industrial production.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scanning electron microscope image of a low silicon X molecular sieve product M0.

FIG. 2 is a scanning electron microscope image of a low-silicon X molecular sieve product M1.

FIG. 3 is a scanning electron microscope image of a low silicon X molecular sieve product M2.

FIG. 4 is a scanning electron microscope image of a low silicon X molecular sieve product M3.

FIG. 5 is a scanning electron microscope image of a low-silicon X molecular sieve product M4.

FIG. 6 is a scanning electron microscope image of a low silicon X molecular sieve product M5.

Figure 7 is a comparison of XRD patterns of low-silicon X molecular sieve synthesized by mother liquor recycling.

Figure 8 shows the comparison of the adsorption performance of the low-silicon X molecular sieve synthesized by circulating mother liquor.

M0 is the low-silicon molecular sieve product produced in the first pass without the mother liquor in the formula; M1 is the low-silicon molecular sieve product produced in the first pass after all the mother liquors synthesized by M0 are synthesized It is a low-silicon molecular sieve product produced by re-formulating the entire mother liquor obtained by synthesizing M1, that is, the second mother liquor, and so on.

detailed description

The following describes the application in detail with reference to the embodiments, but the application is not limited to these embodiments.

Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels, and the equipment and equipment used adopt the parameters recommended by the manufacturers.

In the embodiment, the instrument used for quantitative detection of components is Dionex ICS-3000 multifunctional ion chromatography; the detection method is external standard quantitative method.

Example 1

8.3 g of industrial grade aluminum oxide was weighed into the reaction kettle, 41.6 g of 30% sodium hydroxide solution was added, 5.5 g of potassium hydroxide was added, and 20.1 g of deionized water was added. After stirring, the solution was dissolved at 140 ° C to obtain a solution A0. ; 8.0 g of deionized water was added to 16.0 g of water glass to obtain solution B0; B0 was slowly added to A0 with stirring, and the obtained gel was placed in an oven, aged at 70 ° C. for 8 hours, and crystallized at 100 ° C. 6 After hours, the reaction kettle was taken out, and the mother liquor MY1 was obtained by filtration. The filter cake was washed and dried to obtain the product M0.

Ion chromatography external standard method was used to quantitatively detect the composition of the mother liquor MY1. 26 mmol / L methanesulfonic acid was used as the eluent. Based on the response relationship between the ion conductivity peak area and the ion concentration, the ions of the related substances in the mother liquor were detected. Concentration, the mass fraction of the residual substance in the mother liquor is converted by the ion concentration, and the formulation is reformed according to the composition of the residual substance in the mother liquor.

Weigh 7.8 grams of industrial-grade aluminum trioxide into a reaction kettle, add all the mother liquor MY1 obtained by the above filtration, add 2.0 grams of potassium hydroxide, stir well and dissolve at 140 ° C to obtain solution A1; add 16.0 grams of water glass 8.0 g of deionized water to obtain solution B1; B1 was slowly added to A1 with stirring, and the obtained gel was placed in an oven, aged at 60 ° C for 10 hours, and crystallized at 100 ° C for 8 hours. The reaction kettle was taken out and filtered The mother liquor MY2 is obtained, and the filter cake is washed and dried to obtain the product M1.

Quantitative detection of the composition of MY2, the detection method is as described above.

Weigh 7.5 grams of industrial grade aluminum oxide into the reaction kettle, add all the mother liquor MY2 obtained by the above filtration, add 2.0 grams of potassium hydroxide, and add 3.2 grams of 30% sodium hydroxide solution. After stirring, dissolve at 140 ° C to obtain Solution A2; 8.0 g of deionized water was added to 16.0 g of water glass to obtain solution B2; B2 was slowly added to A2 with stirring, and the resulting gel was placed in an oven and aged at 65 ° C for 8 hours. After 5.5 hours, the reaction kettle was taken out, and the mother liquor MY3 was obtained by filtration; the filter cake was washed and dried to obtain the product M2.

Quantitative detection of the composition of MY3, the detection method is as described above.

Weigh 7.2 grams of industrial grade aluminum oxide into the reaction kettle, add all the mother liquor MY3 obtained by the above filtration, add 2.0 grams of potassium hydroxide, and add 5.4 grams of 30% sodium hydroxide solution. After stirring, dissolve at 140 ° C to obtain Solution A3; 8.0 grams of deionized water was added to 16.0 grams of water glass to obtain solution B3; B3 was slowly added to A3 with stirring, and the resulting gel was placed in an oven, aged at 60 ° C for 9 hours, and crystallized at 100 ° C. After 6 hours, the reaction kettle was taken out, and the mother liquor MY4 was obtained by filtration. The filter cake was washed and dried to obtain the product M3.

Quantitative detection of the composition of MY4, the detection method is as described above.

Weigh 7.2 grams of industrial grade aluminum oxide into the reaction kettle, add all the mother liquor MY4 obtained by the above filtration, add 2.1 grams of potassium hydroxide, add 30 grams of sodium hydroxide solution 5.0 grams, stir and dissolve at 140 ° C to obtain a solution. A4; 8.0 g of deionized water was added to 16.0 g of water glass to obtain solution B4; B4 was slowly added to A4 with stirring, and the resulting gel was placed in an oven, aged at 60 ° C for 8 hours, and crystallized at 100 ° C. After 6.5 hours, the reaction kettle was taken out, and the mother liquor MY5 was obtained by filtration. The filter cake was washed and dried to obtain the product M4.

Quantitative detection of the composition of MY5, the detection method is as described above.

Weigh 7.1 grams of industrial grade aluminum oxide into the reaction kettle, add all the mother liquor MY5 obtained by the above filtration, add 2.2 grams of potassium hydroxide, and add 8.0 grams of 30% sodium hydroxide solution. After stirring, dissolve at 140 ° C to obtain Solution A5; 8.0 grams of deionized water was added to 16.0 grams of water glass to obtain solution B5; B5 was slowly added to A5 with stirring, and the resulting gel was placed in an oven and aged at 55 ° C for 10 hours at 100 ° C. After crystallization for 7 hours, the reaction kettle was taken out, and the mother liquor MY6 was obtained by filtration. The filter cake was washed and dried to obtain the product M5.

Example 2 Analysis of Sample Morphology

Sample morphology analysis of M0-M5, the results are shown in Figures 1-6.

The instrument used for morphology analysis was Hitachi TM 3000 desktop scanning electron microscope, with an acceleration voltage of 15 kV;

It can be seen from Fig. 1 to Fig. 6 that the crystal shape of the sample is stable without the presence of stray crystals.

Example 3 Sample phase analysis

Crystal phase analysis was performed on M0-M5, and the results are shown in FIG. 7.

Instruments for analysis of crystalline phase type PANalytical X'Pert PRO X- ray diffractometer, Cu target, Kα radiation power (λ = 0.15418nm), voltage 40kV, current of 40mA, a scan range 5 ° -60 ^°;;

It can be seen from Figure 7 that the XRD patterns of the molecular sieve synthesized from the mother liquor cycle and the molecular sieve synthesized from the new raw materials are basically the same, and both can obtain high-purity low-silicon molecular sieve products.

Example 4 Carbon dioxide adsorption performance analysis of samples

Carbon dioxide adsorption performance analysis was performed on M0-M5.

The instrument used for the analysis of carbon dioxide adsorption performance was a Micromeritics ASAP2020 physical adsorption instrument. The sample was vacuum-heated and pretreated at 350 ° C for 4h. The free volume of the sample tube was measured with He as the medium, and carbon dioxide was used as the adsorption gas at 25 ° C, 1.9 ～ The physical adsorption measurement was performed at 300 mmHg.

It can be seen from Fig. 8 that under different pressures, the adsorption amount of carbon dioxide by the products M0-M5 remains basically unchanged. Therefore, under the premise of ensuring the synthesis effect, the mother liquor recycling synthesis saves the cost of raw materials and reduces environmental pollution.

The above are just a few examples of the present application, and do not limit the application in any form. Although the present application is disclosed in the preferred embodiment as above, it is not intended to limit the application. Any person skilled in the art, Without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to an equivalent implementation case, and all fall within the scope of the technical solution.

Claims

A method for recycling a low-silicon X molecular sieve to synthesize a mother liquor, characterized in that the method includes the following steps:

1) Mix the aluminum source, sodium source, potassium source, and water to obtain solution A0; mix the silicon source and water to obtain solution B0; add B0 to A0, and age and crystallize the resulting mixture C0. Silicon X molecular sieve and mother liquor;

2) Quantitative detection of components in the mother liquor by ion chromatography external standard method;

3) According to the detection result of step 2), aluminum source, sodium source, and potassium source are added to the mother liquor after quantitative detection to obtain a mixture An; a silicon source is mixed with water to obtain a solution Bn, and Bn is added to An. After the mixture Cn is aged and crystallized, a low-silicon X molecular sieve and a mother liquor are separated;

4) Repeat steps 2) to 3) repeatedly to realize the recycling of mother liquor in the synthesis of low-silicon X molecular sieve.
The method for recycling a low-silicon X molecular sieve synthesis mother liquor according to claim 1, wherein in the mixture C0 of step 1), the molar ratio of the sodium source, potassium source, aluminum source, silicon source, and water is:

Na 2 O (2.0 ～ 6.0): K 2 O (1.0 ～ 4.0): Al 2 O 3 (1.0 ～ 2.5): SiO 2 (0.5 ～ 2.0): H 2 O (80 ～ 150);

Wherein, the number of moles of the sodium source is calculated as the number of moles of Na 2 O; the number of moles of the potassium source is calculated as the number of moles of K 2 O; the number of moles of the aluminum source is calculated as the number of moles of Al 2 O 3 ; The number of moles of the silicon source is calculated as the number of moles of SiO 2 ; the number of moles of the water is calculated as the number of moles of H 2 O.
The method for recycling mother liquor of low-silicon X molecular sieve synthesis according to claim 1, characterized in that, in the mixture Cn of step 3), the molar ratio of the sodium source, potassium source, aluminum source, silicon source and water is:

Na 2 O (2.0 ～ 6.0): K 2 O (1.0 ～ 4.0): Al 2 O 3 (1.0 ～ 2.5): SiO 2 (0.5 ～ 2.0): H 2 O (80 ～ 150);

Wherein, the number of moles of the sodium source is calculated as the number of moles of Na 2 O; the number of moles of the potassium source is calculated as the number of moles of K 2 O; the number of moles of the aluminum source is calculated as the number of moles of Al 2 O 3 ; The number of moles of the silicon source is calculated as the number of moles of SiO 2 ; the number of moles of the water is calculated as the number of moles of H 2 O.
The method for recycling mother liquor of low-silicon X molecular sieve synthesis according to claim 1, characterized in that the aging in step 1) and step 3) is aging at 55 ° C to 70 ° C for 6 to 10 hours.
The method for recycling a low-silicon X molecular sieve synthesis mother liquor according to claim 1, wherein the crystallization in step 1) and step 3) is crystallization at 100 ° C to 110 ° C for 5 to 9 hours.
The method for recycling mother liquor of low-silicon X molecular sieve synthesis according to claim 1, characterized in that said ion chromatography external standard method uses methanesulfonic acid as an eluent, and the response of the peak area of ion conductivity and the ion concentration Based on the relationship, the ion concentration in the mother liquor is detected, and the mass fraction of each component in the mother liquor is converted by the ion concentration.
The method for recycling a low-silicon X molecular sieve synthesis mother liquor according to claim 6, wherein the eluent is 26 mmol / L methanesulfonic acid.
The method for recycling a low-silicon X molecular sieve synthesis mother liquor according to claim 1, wherein the sodium source is selected from at least one of sodium sulfate, sodium nitrate, and sodium hydroxide;

The potassium source is selected from at least one of potassium sulfate, potassium nitrate, and potassium hydroxide;

The silicon source is selected from at least one of silica sol, sodium silicate, and potassium silicate;

The aluminum source is selected from at least one of pseudo-boehmite, alumina, sodium aluminate, potassium aluminum sulfate, and potassium aluminate.
The method for recycling a low-silicon X molecular sieve synthesis mother liquor according to claim 1, wherein the low-silicon X molecular sieve has an adsorption amount of CO 2 higher than 100 cm 3 / at a temperature of 25 ° C and a CO 2 pressure of 250 mmHg. g.
The method for recycling mother liquid of low-silicon X molecular sieve synthesis according to claim 1, characterized in that the adsorption amount of the low-silicon X molecular sieve on CO 2 is 100 cm 3 / g at 25 ° C and a CO 2 pressure of 250 mmHg. ~ 120cm 3 / g.