CN104340990B - A kind of synthetic method of y-type zeolite - Google Patents

Abstract

A method for synthesizing Y-type zeolite, comprising converting kaolin into metakaolin by roasting and dehydrating at 500-860° C., pulverizing, and then making metakaolin powder with a particle size of less than 230 microns, and mixing metakaolin powder with recovered mother liquor, guiding agent, Sodium hydroxide solution, water, and optionally water glass, prepared in a molar ratio of (1-2.5) Na ₂ O : Al ₂ O ₃ : (4-9) SiO ₂ : (40-450) H ₂ O Reaction raw material mixture, crystallize said reaction raw material mixture under stirring at 80-100°C, then filter and dry, it is characterized in that said recovery mother liquor comes from the synthesis process of gel method Y-type zeolite, and its concentration is SiO ₂ ≤150g/L, Na ₂ O ≤70g/L, SO ₄ ^2‑ ≤100g/L. The synthesis method of Y-type zeolite provided by the present invention effectively utilizes the silicon and sodium in the mother liquor of the Y-type zeolite synthesized by the gel method, reduces the discharge of pollutants containing sulfate radicals in the mother liquor, and the mother liquor synthesized by the gel method does not need to be pretreated , Direct use.

Description

A kind of synthetic method of Y type zeolite

technical field

The present invention relates to a kind of synthesis method of Y-type zeolite, further say the present invention relates to the method for utilizing Y-type zeolite synthetic mother liquor to synthesize Y-type zeolite.

Background technique

Y-type zeolite is the most widely used molecular sieve in petrochemical industry. The annual production capacity of Y-type zeolite in my country has reached more than 50,000 tons, and it is growing. At present, the production process of Y-type zeolite has gel directing agent method (U.S. Grace Company, USP3,639,099 and USP4,166,099), kaolin microsphere in-situ crystallization method (BASF Company, USP4,493,902 ) and in-situ crystallization of raw kaolin powder (Sinopec, CN15333982A). The gel method uses NaOH, sodium aluminate, sodium metasilicate (water glass), aluminum sulfate, etc. as raw materials, and adds 5-10% of the directing agent, and synthesizes molecular sieves by hydrothermal crystallization. The in-situ crystallization method of kaolin microspheres is to first spray-dry kaolin into microspheres, mix kaolin microspheres with water glass, liquid alkali, and directing agent, and synthesize them by hydrothermal crystallization to obtain molecular sieves. The in-situ crystallization method of raw kaolin powder is to directly mix kaolin powder with water glass, liquid caustic soda, and directing agent, and then synthesize it by hydrothermal crystallization to obtain molecular sieves. In the above three synthetic methods, in order to increase the silicon-aluminum ratio of the product, the silicon-aluminum ratio of the feed is higher, even up to 9 or more, and the silicon-aluminum ratio of the product is generally about 5, so about 40% The silicon is not used, these silicon enters the synthetic mother liquor after filtration, the amount of silicon in the mother liquor is relatively large, the concentration of silicon is not high, generally less than 100g/L, and the modulus is also low, generally less than 3.0, especially the gel It also contains a lot of sulfate radicals.

For the recovery and utilization of synthetic mother liquor, GRACE company has disclosed in the conventional gel method NaY synthesis of US4164551 that mother liquor is collected, then in mother liquor, add acidic aluminum salt such as aluminum sulfate, adjust pH value to form silica-alumina colloid, reuse to conventional Synthesis of NaY zeolite by gel method. This method and subsequent improved methods solve the problem of utilizing the silicon source in the mother liquor, but a large amount of waste water containing sodium sulfate still needs to be discharged, and the silica-alumina gel cannot be fully utilized, and the excess silica-alumina gel needs to be further processed.

There are two forms of sodium in the NaY mother liquor of the conventional gel method, sodium hydroxide and sodium sulfate. Sodium saturated crystallization is precipitated, sodium sulfate crystals and filtrate are separated, and the product sodium sulfate is Na ₂ SO ₄ ·10H ₂ O, which can be used as a raw material for other processes. A part of the gel-containing filtrate is directly used in the synthesis of NaY, which can reduce the consumption of water glass and liquid caustic soda in the feed; the other part can be used to prepare the catalyst, and the silicon concentrated in the filtrate is used as the binder of the catalyst. However, these treatment methods only partially solve the discharge problem of sodium sulfate-containing waste liquid, and the energy consumption is high.

In US4493902, kaolin is roasted at high and low temperatures to prepare microspheres, and Y-type zeolite is synthesized by in-situ crystallization of microspheres, and the mother liquor is reused. The mother liquor reuse treatment of this process is concentrated by evaporation. However, because the concentration of silicon in the mother liquor is relatively low, the discharge of the mother liquor is relatively large, so the workload of the concentration treatment is large and the energy consumption is high.

CN1709794A adopts kaolin as raw material, synthesizes Y-type zeolite composite material through in-situ crystallization technology, and realizes the direct reuse of filtered mother liquor after synthesis by this process to replace liquid caustic soda and part of water glass.

Contents of the invention

The inventors of the present invention unexpectedly found through a large number of experiments that the synthetic mother liquor obtained by the gel method can be directly used without treatment in the method for synthesizing Y-type zeolite by in-situ crystallization of kaolin raw powder, reducing the discharge of the synthetic mother liquor by the gel method The pollution caused, and changed the conventional treatment method that could be recycled to the synthetic process of gel method Y-type zeolite after adding acidic aluminum salt to make silica-alumina gel. Based on this, the present invention is formed.

The synthesis method of Y-type zeolite provided by the present invention is to convert kaolin into metakaolin by roasting and dehydrating at 500-860° C., pulverize, and then make metakaolin powder with a particle size of less than 230 microns, mix metakaolin powder with recovered mother liquor, guide agent, sodium hydroxide solution, water and optional water glass to make a molar ratio of (1-2.5) Na ₂ O : Al ₂ O ₃ : (4-9) SiO ₂ : (40-450) H ₂ The reaction raw material mixture of O, said reaction raw material mixture is crystallized under stirring at 80-100 ℃, then filtered and dried, it is characterized in that said reclaimed mother liquor comes from the synthetic process of gel method Y-type zeolite, and its concentration is: SiO ₂ ≤150g/L, Na ₂ O≤70g/L, SO ₄ ^2- ≤100g/L.

The synthetic method of Y-type zeolite provided by the present invention can obtain the Y-type zeolite synthesized by conventional kaolin raw powder in-situ crystallization method, and the advantage of this method is:

1. Silicon and sodium in the mother liquor of Y-type zeolite synthesized by gel method are effectively utilized.

2. The emission of pollutants containing sulfate radicals in the mother liquor of Y-type zeolite synthesized by gel method is reduced.

3. The mother liquor for synthesizing Y-type zeolite by the gel method can be directly used for synthesizing Y-type zeolite by the in-situ crystallization method of raw kaolin powder without pretreatment, which simplifies the mother liquor treatment and synthesis steps.

detailed description

The synthesis method of Y-type zeolite provided by the present invention is to convert kaolin into metakaolin by roasting and dehydrating at 500-860° C., pulverize, and then make metakaolin powder with a particle size of less than 230 microns, mix metakaolin powder with recovered mother liquor, guide agent, sodium hydroxide solution, water and optional water glass to make a molar ratio of (1-2.5) Na ₂ O : Al ₂ O ₃ : (4-9) SiO ₂ : (40-450) H ₂ The reaction raw material mixture of O, said reaction raw material mixture is crystallized under stirring at 80-100 ℃, then filtered and dried, it is characterized in that said reclaimed mother liquor comes from the synthetic process of gel method Y-type zeolite, and its concentration is: SiO ₂ ≤150g/L, Na ₂ O≤70g/L, SO ₄ ^2- ≤100g/L.

In the method provided by the invention, said kaolin is selected from hard kaolin or soft kaolin; its crystal content should be greater than 75% by weight, preferably greater than 85% by weight, and its average particle size is less than 4 microns, so it is a raw material without molding treatment. earth.

In the method provided by the invention, said kaolin also can be the kaolin obtained through acid or alkali or salt treatment, and said acid can be inorganic acids such as hydrochloric acid, nitric acid, acetic acid, oxalic acid, oxalic acid, sulfuric acid, phosphoric acid and Organic acid, wherein preferred hydrochloric acid and nitric acid; said alkali can be sodium hydroxide, potassium hydroxide, ammoniacal liquor etc., wherein preferred sodium hydroxide; said salt is selected from sodium carbonate or sodium bicarbonate.

The calcination temperature of the kaolin is 500-900°C, preferably 500-700°C, more preferably 640-680°C, and the general calcination time is 1-10 hours.

The directing agent can be synthesized according to conventional methods, for example, according to the preparation methods of USP3574538, USP3639099, USP3671191, USP4166099 and EUP0435625. The composition of the directing agent is preferably: (10-17) SiO ₂ : (0.7-1.3) Al ₂ O ₃ : (1-18) Na ₂ O: (200-450) H ₂ O. The directing agent is preferably obtained by aging at 4-20°C.

The recovered mother liquor in the present invention comes from the synthesis process of the gel-method Y-type zeolite, and is the primary filtrate obtained by filtration, or a mixed solution of the primary filtrate and the subsequent cleaning solution. Said filtering method may be centrifugal separation, belt filter and the like. The mother liquor recovered by the gel method has a concentration of SiO ₂ ≤ 150g/L, Na ₂ O ≤ 70g/L, and SO ₄ ^2- ≤ 100g/L; in a preferred case, the mother liquor recovered by the gel method , its concentration is SiO ₂ 20～100g/L, Na ₂ O 15～70g/L, SO ₄ ^2- 5～100g/L; in a further preferred situation, said gel method recovers the mother liquor, its concentration is SiO ₂ 20-50g/L, Na ₂ O 18-30g/L, SO ₄ ^2- 5-60g/L. For example, in a specific embodiment of the present invention, its concentration can be SiO ₂ 28.5g/L, Na ₂ O 22.6g/L, SO ₄ ^2- 25g/L; in another specific embodiment of the present invention Among them, its concentration can be SiO ₂ 20.2g/L, Na ₂ O 18.6g/L, SO ₄ ^2- 40g/L; in another specific embodiment of the present invention, its concentration can be SiO ₂ 38.5g/L L, Na ₂ O 28.6g/L, SO ₄ ^2-60g /L.

Said water glass is to determine whether it is added in the reaction raw material mixture according to the needs of the reaction raw material mixture proportioning.

Said crystallization can be carried out under stirring or standing still. If it is crystallization under stirring, the stirring speed is 100-1000 rpm, preferably 400-600 rpm, and the time is 16-48 hours, preferably 24-32 hours. The drying temperature of the zeolite after crystallization is 100-120°C.

The present invention will be further described below by embodiment, but content of the present invention is not limited thereby.

The NaY content of the zeolite in the examples is obtained according to the relative crystallinity determined by the RIPP146-90 standard method; the unit cell constant a ₀ is determined according to the RIPP145-90 standard method.

The zeolite silicon-aluminum ratio data is calculated according to the following formula:

SiO ₂ /Al ₂ O ₃ (molar ratio)=2×(2.5858-a ₀ )/(a _0-2.4191 ), where the unit of unit cell constant a ₀ is nm.

Example 1

Preparation of directing agent: Take 250 grams of sodium silicate solution (containing 20.05% by weight of SiO ₂ , 6.41% by weight of Na ₂ O), slowly add 120 grams of sodium metaaluminate solution (containing 3.15% by weight of Na 2 O) under rapid stirring at 30°C Al ₂ O ₃ , 21.1% by weight of Na ₂ O), stirred at a constant temperature of 30°C for 1 hour, and statically aged at 20°C for 24 hours to obtain a directing agent. The composition of the directing agent is 16Na ₂ O:Al ₂ O ₃ :15SiO ₂ :320H ₂ O.

Kaolin with an average particle size of 4 μm (Suzhou, Yangshan brand, China Kaolin Company, crystal content of 80% by weight) was roasted at 660°C for 3 hours to obtain metakaolin powder, which was pulverized to produce metakaolin powder with a particle size of less than 230 μm .

Take 80 grams of metakaolin powder, add 2600 grams of conventional industrial gel method NaY synthesis mother liquor (containing SiO ₂ 28.5g/L, Na ₂ O 22.6g/L, SO ₄ ^2- 25g/L), and 60 grams of directing agent under stirring , 80 grams of concentration is 5% by weight of sodium hydroxide solution. Raise the temperature to 90° C. and stir for crystallization at a constant temperature for 28 hours, and the stirring speed is 400 rpm during feeding and crystallization. After the crystallization, the crystallization tank was cooled, filtered, and washed with water until the pH value of the washing solution was less than 10. Drying at 120° C. for 2 hours gave zeolite Y-1.

X-ray diffraction determined that the NaY content in Y-1 was 72.4% by weight, and the unit cell constant was 2.472nm. The zeolite silica-alumina ratio is 4.30.

Example 2

Take 80 grams of metakaolin powder, add 2900 grams of conventional industrial gel method NaY synthesis mother liquor (containing SiO ₂ 20.2g/L, Na ₂ O 18.6g/L, SO ₄ ^2- 40g/L) under stirring, 60 grams of Example 1 prepared directing agent, 76 grams of concentration is 5% by weight of sodium hydroxide solution. Raise the temperature to 90° C. and stir for crystallization at a constant temperature for 28 hours, and the stirring speed is 400 rpm during feeding and crystallization. After the crystallization is finished, the crystallization tank is cooled, filtered,

Wash with water until the pH value of the washing solution is less than 10. Dry at 120° C. for 2 hours to obtain zeolite Y-2.

X-ray diffraction determined that the NaY content in Y-2 was 75.4% by weight, and the unit cell constant was 2.469nm. The zeolite silica-alumina ratio is 4.67.

Example 3

Take 80 grams of metakaolin powder, add 1800 grams of conventional industrial gel method NaY synthesis mother liquor (containing SiO ₂ 38.5g/L, Na ₂ O 28.6g/L, SO ₄ ^2-60g /L) under stirring, 60 grams of Example 1 The prepared directing agent, 75 grams of industrial water glass (containing SiO ₂ 258.5g/L, Na ₂ O 80.6g/L), 75 grams of sodium hydroxide solution with a concentration of 5% by weight. The temperature was raised to 90° C. and stirred at constant temperature for 26 hours for crystallization, and the stirring speed was 400 rpm during feeding and crystallization. After the crystallization was completed, the crystallization tank was cooled, filtered, and washed with water until the pH value of the washing solution was less than 10. Drying at 120° C. for 2 hours gave zeolite Y-3.

The NaY content in Y-3 was determined to be 72.9% by weight by X-ray diffraction, and the unit cell constant was 2.471nm. The zeolite silica-alumina ratio is 4.42.

Example 4

Take 80 grams of metakaolin powder, add 1400 grams of conventional industrial gel method NaY synthesis mother liquor (containing SiO ₂ 38.5g/L, Na ₂ O 28.6g/L, SO ₄ ^2-60g /L) under stirring, 60 grams of Example 1 The prepared directing agent, 81 grams of industrial water glass (containing SiO ₂ 258.5g/L, Na ₂ O 80.6g/L), 78 grams of sodium hydroxide solution with a concentration of 5% by weight. The temperature was raised to 90° C. and stirred at constant temperature for 26 hours for crystallization, and the stirring speed was 400 rpm during feeding and crystallization. After the crystallization was completed, the crystallization tank was cooled, filtered, and washed with water until the pH value of the washing solution was less than 10. Drying at 120° C. for 2 hours gave zeolite Y-4.

The NaY content in Y-4 was determined to be 75.9% by weight by X-ray diffraction, and the unit cell constant was 2.468nm. The zeolite silica-alumina ratio is 4.82.

Example 5

Take 80 grams of metakaolin powder, add 1000 grams of conventional industrial gel method NaY synthesis mother liquor (containing SiO ₂ 38.5g/L, Na ₂ O 28.6g/L, SO ₄ ^2-60g /L) under stirring, 60 grams of Example 1 The prepared directing agent, 170 grams of industrial water glass (containing SiO ₂ 258.5g/L, Na ₂ O 80.6g/L), 94 grams of 5% by weight sodium hydroxide solution. The temperature was raised to 90° C. and stirred at constant temperature for 26 hours for crystallization, the speed of feeding and stirring was 400 rpm, and the mixture was left standing for crystallization. After the crystallization was completed, the crystallization tank was cooled, filtered, and washed with water until the pH value of the washing solution was less than 10. Drying at 120° C. for 2 hours gave zeolite Y-5.

The NaY content in Y-5 was determined to be 71.9% by weight by X-ray diffraction, and the unit cell constant was 2.468nm. Zeolite silica alumina is 4.82.

Claims (11)

1. a kind of synthetic method of y-type zeolite, is that kaolin is calcined into dehydration at 500-860 DEG C to change into metakaolin, crushes, Particle diameter is made again and is less than 230 microns of metakaolin powder, by metakaolin powder with reclaim mother liquor, directed agents, sodium hydroxide solution, Water and with optional waterglass, mol ratio is made for (1-2.5) Na₂O：Al₂O₃：(4-9)SiO₂：(40-450)H₂O reaction Raw mixture, crystallization under described reacting material mixture is stirred at 80-100 DEG C, then filters and dries, and its feature exists Building-up process of the mother liquor from gel method y-type zeolite is reclaimed in described, its concentration is SiO₂20~50g/L, Na₂O18~30g/ L, SO₄ ^2-5~60g/L.

2. according to the method for claim 1 wherein described kaolin is selected from hard kaolin, soft kaolin or gangue.

3. according to the method for claim 2, wherein, crystalline content is more than 75 heavy % in described kaolin.

4. according to the method for claim 3, wherein, crystalline content is more than 85 heavy % in described kaolin.

5. according to method any in Claims 1 to 4, wherein, described kaolin is to be obtained through peracid or alkali or salt treatment Kaolin, the one kind or its mixture of described acid in hydrochloric acid, nitric acid, acetic acid, ethanedioic acid, oxalic acid, sulfuric acid, phosphoric acid, The one kind or its mixture of described alkali in sodium hydroxide, potassium hydroxide, ammoniacal liquor, described salt are selected from sodium carbonate or carbonic acid Hydrogen sodium.

6. according to the method for claim 5, wherein, described acid is hydrochloric acid or nitric acid.

7. according to the method for claim 5, wherein, described alkali is sodium hydroxide.

8. according to the method for claim 1 wherein, described kaolin, be calcined at 500~700 DEG C dehydrations change into it is higher Ridge soil.

9. according to the method for claim 8, wherein, described kaolin, be calcined at 640~680 DEG C dehydrations change into it is higher Ridge soil.

10. it is according to the method for claim 1 wherein, described directed agents, constituting：(10-17)SiO₂：(0.7-1.3) Al₂O₃：(1-18)Na₂O：(200-450)H₂O。

11. according to the method for claim 1 or 10, wherein, described directed agents are obtained through aging at 4~20 DEG C.