CN107720776B

CN107720776B - Synthesis method of sodium-free FAU type molecular sieve

Info

Publication number: CN107720776B
Application number: CN201710993680.5A
Authority: CN
Inventors: 张耀日; 裴仁彦; 霍志萍; 张丽娟; 石芳; 于海斌
Original assignee: CNOOC Energy Technology and Services Ltd; CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Current assignee: CNOOC Energy Technology and Services Ltd; CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Priority date: 2017-10-23
Filing date: 2017-10-23
Publication date: 2020-02-18
Anticipated expiration: 2037-10-23
Also published as: CN107720776A

Abstract

The invention discloses a synthesis method of a sodium-free FAU type molecular sieve, which comprises the following steps: crystallizing a phosphorus source, an aluminum source, a silicon source, organic alkali and deionized water at a certain temperature and under autogenous pressure to obtain a FAU type molecular sieve free of Na ions, and washing, drying and roasting the FAU type molecular sieve to prepare the sodium-free FAU type molecular sieve; the organic alkali and the template are both tetramethylammonium hydroxide and tetrapropylammonium hydroxide. Compared with the catalyst adopted in the prior art, the molecular sieve prepared by the method does not contain Na ions, does not need complicated ion exchange and water washing processes, and is an environment-friendly FAU type molecular sieve synthesis method. The sodium-free FAU molecular sieve synthesized by the method has stable skeleton, higher catalytic activity and long service life.

Description

Synthesis method of sodium-free FAU type molecular sieve

Technical Field

The invention belongs to the field of inorganic catalytic carrier materials, and relates to a carrier material for synthesizing a FAU type molecular sieve without sodium ions in one step.

Background

The FAU type molecular sieve used in the industry at present is mainly NaY type molecular sieve, Y type zeolite has three-dimensional smooth pore structure and excellent thermal and hydrothermal stability, and is widely applied to petroleum refining and chemical industry, and especially plays an irreplaceable role in catalytic cracking (FCC) reaction. Meanwhile, the Y-type molecular sieve also shows excellent performance on the adsorption of organic volatile matters.

At present, the industrial production method of Y-type molecular sieve is basically the conventional Y-type molecular sieve prepared by adopting the directing agent method mentioned in USP3639099 and USP4166099 by GRACE in the United states. In the production process of a catalytic cracking catalyst, particularly a Y-type molecular sieve, the content of metallic sodium is reduced by adopting ammonium salt in the traditional process, and because the sodium is in different positions and different steric hindrance in the molecular sieve, excessive ammonium salt is often needed to ensure that the sodium content of the molecular sieve and the sodium content of the catalyst meet the index requirement, so that high-concentration ammonia nitrogen sewage is inevitably generated, and the environmental pollution is caused.

According to statistics, the main lakes in China are in eutrophication state due to nitrogen and phosphorus pollution, and account for 56% of the total amount of the lakes. The water body eutrophication is caused by the discharge of a large amount of nitrogen-containing waste water, and a water bloom is formed in rivers or lakes and a red tide is formed in the sea. Algae in water reproduce in a large amount by taking nitrogen sources as nutrient substances, water balance is damaged, growth of aerobic organisms and photosynthetic organisms in water is influenced, released algae toxins influence normal growth and reproduction of fishes and shrimps, and people eat fishes and shrimps containing algae toxins, so that poisoning is caused if the fishes and shrimps are improperly treated, and life safety is seriously threatened. The main technologies for treating ammonia nitrogen at present are as follows: the method comprises the steps of biological denitrification, stripping, breakpoint chlorination, ion exchange, chemical precipitation, catalytic wet oxidation, electrodialysis, liquid membrane, electrolysis and the like, but most of the methods have the defects of large investment, complex operation, high operation cost and the like, and a method for treating high-concentration ammonia nitrogen wastewater efficiently, economically and stably does not exist in any scheme, and some processes bring secondary pollution while ammonia nitrogen is removed. Therefore, in the modification and preparation processes of the zeolite and the catalyst, the new technology is adopted to reduce the use amount of ammonium salt, and the ammonia nitrogen pollution is relieved from the source, so that the method is an effective environmental protection measure and has important value

CN00133566.9 discloses a preparation method of a Y-type molecular sieve, which comprises the steps of firstly exchanging an NaY molecular sieve with ammonium ions and rare earth ions and carrying out hydrothermal roasting, and then reacting and combining the NaY molecular sieve with a phosphorus compound to obtain 0.2-10 wt% of P₂O₅And then carrying out hydrothermal roasting. The Y-type molecular sieve obtained by the method can obviously reduce the olefin content of FCC gasoline, and can keep good coke selectivity.

CN103964463A discloses a preparation method of a Y-type molecular sieve, which comprises the steps of taking a NaY molecular sieve as a raw material, washing a molecular sieve filter cake by using an alkali liquor with the mass 2-8 times of the dry basis mass of the molecular sieve when fresh NaY molecular sieve crystallized slurry is filtered and separated; then, a compound solution containing H + ions is added into the NaY molecular sieve slurry, and the sodium in the zeolite is exchanged by H +.

CN101823726B discloses a modified Y molecular sieve, which is obtained by carrying out primary exchange reaction on a NaY molecular sieve and a rare earth solution, then introducing a phosphorus compound into exchange slurry, further reacting, filtering, washing and roasting a filter cake under the condition of water vapor. The unit cell constant of the modified Y molecular sieve is 2.450-2.479 nm, wherein the unit cell constant contains 2.0-6.0 wt% of sodium oxide, 0.01-2.5 wt% of phosphorus and 11-23 wt% of rare earth oxide. Most of the modified molecular sieve rare earth is positioned in a sodalite cage of the Y molecular sieve, so that the stability of the molecular sieve in a high-temperature hydrothermal environment is improved; the method has good modulation effect on the structural acidity of the molecular sieve. The modified Y molecular sieve of the invention is used as an active component of a cracking catalyst, and has strong heavy oil conversion capability and good coke selectivity.

CN102049278A discloses a small-grain Y-type molecular sieve dispersed material, wherein the grain size of a small-grain Y-type molecular sieve in the small-grain Y-type molecular sieve dispersed material is 100-450 nm, and the small-grain Y-type molecular sieve dispersed material is subjected to in-situ crystallization to disperse and grow the small-grain Y-type molecular sieve on a porous substrate. The small-grain Y-type molecular sieve dispersion material has the catalytic performance of the small-grain Y-type molecular sieve, and the dispersion material formed by the small-grain Y-type molecular sieve dispersion material is attached to a special substrate, so that the dispersion material has various catalytic centers and pore channels, and has unique advantages for the catalytic process of macromolecules.

The prior FAU type molecular sieve mostly uses a large amount of ammonium salt in the preparation and modification process, causes environmental pollution, and simultaneously greatly increases the subsequent treatment cost, while the prior method for reducing the use amount of the ammonium salt introduces H⁺Ion exchange, H⁺The introduction of ions can adversely affect the stability, activity, etc. of the molecular sieve. Therefore, in order to reduce the environmental pollution of ammonia nitrogen and improve the performance of the molecular sieve, a preparation method of the FAU type molecular sieve capable of effectively reducing the dosage of ammonium salt is needed.

Disclosure of Invention

The invention aims to solve the technical problem of providing a synthesis method of a sodium-free FAU type molecular sieve, which synthesizes a sodium-free FAU type molecular sieve carrier material in one step without further post-treatment for sodium removal, avoids using a large amount of ammonium salt and is environment-friendly.

In order to solve the technical problems, the invention provides a synthesis method of a sodium-free FAU type molecular sieve, which comprises the following steps: the method comprises the following steps of mixing a silicon source, a phosphorus source, an aluminum source, an organic alkali, a template agent and water in a molar ratio: SiO 2₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂0.09-0.5: 0.8-1: 1: 0.05-0.3: 0.2-0.5: 0.2-0.8: 40-100, and fully stirring and mixing the mixed materials to ensure that the mixture is completely and uniformly stirred. Putting the uniformly stirred reactants into a reaction kettle for crystallization reaction until the crystallization reaction is the FAU type molecular sieve, and finally washing, drying and roasting the crystallized product to prepare the sodium-free FAU type molecular sieve; the organic alkali and the template agent are both tetramethylammonium hydroxide and tetrapropylammonium hydroxide.

In the above technical scheme, the silicon source is silica sol, the aluminum source is aluminum oxide, aluminum sulfate or aluminum nitrate, and preferably the aluminum source is aluminum sulfate. The crystallization temperature in the crystallization process is controlled to be 180-210 ℃, and the crystallization time is 10-60 h.

Compared with the prior art, the method disclosed by the invention overcomes the problems that sodium ions are introduced when the FAU type molecular sieve is synthesized in the prior art, and a large amount of ammonium salt is required to be used for exchanging the sodium ions in the subsequent treatment process, so that serious ammonia nitrogen pollution is generated. In the synthesis process, sodium ions are not introduced, and the FAU type molecular sieve without sodium is directly synthesized by taking organic alkali as an alkali source. The invention is environment-friendly, pollution-free and environment-friendly.

Drawings

FIG. 1 is an XRD pattern of a sodium free FAU type molecular sieve made in example 1 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples and drawings, wherein the procedures, conditions, test methods and the like are all generally known and known in the art, and reagents used therein are commercially available except as specifically mentioned below.

The sample obtained by the invention is subjected to a diffraction experiment by using a Japanese science D/MAX-2500 type X-ray diffraction (XRD) instrument, and whether the sample is a crystal phase of an FAU type molecular sieve or not is contrasted and identified, the measuring conditions comprise a Cu target, a K α ray (lambda is 0.15418nm), Ni filtering, a working voltage of 40kV, a working current of 200mA, a scanning range of 5-55 degrees and a scanning speed of 10 DEG/min, the intensity of a diffraction peak is calculated by the percentage of the peak height of the diffraction peak to the peak height of the strongest peak, and the deviation of the measured value of the diffraction angle 2 theta is +/-0.20 degrees due to different ratios of silicon oxide to aluminum oxide of different samples and the influence of the grain size and the error of an experimental instrument.

Example 1

325g of phosphoric acid (H) are weighed₃PO₄85wt percent of the total weight of the components are put into a beaker, 1000g of deionized water is weighed and evenly mixed with phosphoric acid in the beaker, and 216.5g of SB powder (Al) is taken₂O₃Content 74 wt%) was placed in a beaker and mixed with a dilute phosphoric acid solution to obtain mixture A. 30g of silica Sol (SiO)₂30 wt%) was added to a solution of 50g of tetramethylammonium hydroxide (25 wt% TMAOOH) and 90g of tetrapropylammonium hydroxide (40 wt% TPAOH), and the mixture was stirred until uniform to obtain a mixed solution B. Finally, adding the mixed solution B into the mixture A, stirring and kneading the mixture A until the mixture A is uniform, wherein the ratio of the final mixture is SiO₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂O ═ 0.1:0.9:1:0.09:0.2:0.29: 41. And adding the mixed materials into a reaction kettle, and carrying out dynamic crystallization in the reaction kettle at the temperature of 200 ℃ for 53 hours. After the reaction is finished, a molecular sieve product is obtained through washing, filtering and drying. The XRD spectrum is shown in figure 1, and the FAU type molecular sieve has characteristic peaks and no other mixed crystals as can be seen from figure 1.

Example 2

300g of phosphoric acid (H) are weighed₃PO₄85 wt%) in a beaker, 1300g of deionized water was weighed and mixed with phosphoric acid in the beaker, 216.5g of SB powder (Al)₂O₃Content 74 wt%) was placed in a beaker and mixed with a dilute phosphoric acid solution to obtain mixture A. 81g of silica Sol (SiO)₂ Content 30% by weight) was added to a solution of 100g of tetramethylammonium hydroxide (TMAOOH content 25% by weight) and 150g of tetrapropylammonium hydroxide (TPAOH content 40% by weight)And stirring the mixture until the mixture is uniform to prepare a mixed solution B. Finally, adding the mixed solution B into the mixture A, stirring and kneading the mixture A until the mixture A is uniform, wherein the ratio of the final mixture is SiO₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂O-0.26: 0.83:1:0.17:0.36:0.53: 55.4. And adding the mixed materials into a reaction kettle, and carrying out dynamic crystallization on the reaction kettle at 185 ℃ for 45 hours. And after the reaction is finished, washing, filtering and drying to obtain a sodium-free FAU type molecular sieve product.

Example 3

360g of phosphoric acid (H) are weighed₃PO₄85wt percent of the total weight of the components are put into a beaker, 1100g of deionized water is weighed and evenly mixed with phosphoric acid in the beaker, and 250g of SB powder (Al)₂O₃Content 74 wt%) was placed in a beaker and mixed with a dilute phosphoric acid solution to obtain mixture A. 150g of silica Sol (SiO)₂30 wt%) was added to a solution of 160g of tetramethylammonium hydroxide (25 wt% TMAOOH) and 200g of tetrapropylammonium hydroxide (40 wt% TPAOH), and the mixture was stirred until uniform to obtain a mixed solution B. Finally, adding the mixed solution B into the mixture A, stirring and kneading the mixture A until the mixture A is uniform, wherein the ratio of the final mixture is SiO₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂O ═ 0.41:0.86:1:0.24:0.46:0.7: 45.9. And adding the mixed materials into a reaction kettle, and carrying out dynamic crystallization on the reaction kettle at 180 ℃ for 30 hours. And after the reaction is finished, washing, filtering and drying to obtain a sodium-free FAU type molecular sieve product.

Example 4

290g of phosphoric acid (H) are weighed₃PO₄85 wt%) in a beaker, 1276g of deionized water was weighed and mixed with phosphoric acid in the beaker, 186g of SB powder (Al) was taken₂O₃Content 74 wt%) was placed in a beaker and mixed with a dilute phosphoric acid solution to obtain mixture A. 83g of silica Sol (SiO)₂30 wt%) was added to a solution of 80g of tetramethylammonium hydroxide (25 wt% TMAOOH) and 230g of tetrapropylammonium hydroxide (40 wt% TPAOH), and the mixture was stirred until uniform to obtain a mixed solution B. Finally adding the mixed solution B into the mixtureIn A, stirring and kneading until uniform, and the final mixture ratio is SiO₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂O ═ 0.31:0.93:1:0.16:0.49:0.65: 64.87. And adding the mixed materials into a reaction kettle, and carrying out dynamic crystallization on the reaction kettle at 190 ℃ for 20 hours. And after the reaction is finished, washing, filtering and drying to obtain a sodium-free FAU type molecular sieve product.

Example 5

Weighing 180g of phosphoric acid (H)₃PO₄85wt percent of the total weight of the SB powder is put into a beaker, 1276g of deionized water is weighed and evenly mixed with phosphoric acid in the beaker, 126g of SB powder (Al)₂O₃Content 74 wt%) was placed in a beaker and mixed with a dilute phosphoric acid solution to obtain mixture A. 83g of silica Sol (SiO)₂30 wt%) was added to a solution of 100g of tetramethylammonium hydroxide (25 wt% TMAOOH) and 190g of tetrapropylammonium hydroxide (40 wt% TPAOH), and the mixture was stirred until uniform to obtain a mixed solution B. Finally, adding the mixed solution B into the mixture A, stirring and kneading the mixture A until the mixture A is uniform, wherein the ratio of the final mixture is SiO₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂O ═ 0.45:0.85:1:0.3:0.44:0.74: 94.2. And (3) adding the mixed materials into a reaction kettle, and carrying out dynamic crystallization on the reaction kettle at the temperature of 100 ℃ for 15 hours. And after the reaction is finished, washing, filtering and drying to obtain a sodium-free FAU type molecular sieve product.

Claims

1. A method for synthesizing a sodium-free FAU type molecular sieve is characterized by comprising the following steps:

mixing a silicon source, a phosphorus source, an aluminum source, an organic alkali and water according to a molar ratio, and fully stirring and mixing the mixed materials to ensure that the mixture is completely and uniformly stirred, wherein the molar composition of the silicon source, the phosphorus source, the aluminum source, the organic alkali, a template agent and water is as follows: SiO 2₂:P₂O₅:Al₂O₃:TMA⁺:TPA⁺:OH^-:H₂0.09-0.5: 0.8-1: 1: 0.05-0.3: 0.2-0.5: 0.2-0.8: 40-100; stirring uniformlyPutting the reactants into a reaction kettle for crystallization reaction until the crystallization reaction is the FAU type molecular sieve, and washing, drying and roasting the final crystallization product to obtain the sodium-free FAU type molecular sieve; the organic alkali and the template are both tetramethylammonium hydroxide and tetrapropylammonium hydroxide.

2. The method of synthesizing a sodium-free FAU-type molecular sieve of claim 1, wherein the steps of: the silicon source is silica sol, the aluminum source is aluminum oxide, aluminum sulfate or aluminum nitrate, and the phosphorus source is phosphoric acid.

3. The method of synthesizing a sodium-free FAU-type molecular sieve of claim 1, wherein the steps of: the crystallization temperature is 180-210 ℃, and the crystallization time is 30-100 h.