CN111434611A - NaY molecular sieve synthesis method for improving single-kettle yield - Google Patents

Abstract

A synthesis method for improving the single-pot yield of NaY molecular sieve, characterized in that the method comprises: increasing the Na ₂ O/SiO ₂ molar ratio in the precursor of NaY molecular sieve by 5% to 60% to obtain a gel mixture A, and at room temperature Stir for at least 0.1 hour to obtain gel mixture B, add mineral acid to obtain gel mixture C, gel mixture C is hydrothermally crystallized and the product is recovered, wherein the precursor of the NaY molecular sieve is composed of a directing agent, water glass, aluminum In the precursor of NaY molecular sieve, in terms of moles, Na ₂ O: SiO ₂ =0.2-0.45, SiO ₂ : Al ₂ O ₃ =5-18, H ₂ O: Al ₂ O ₃ =100-200. The method can increase the single-pot yield of synthesizing NaY molecular sieve by 40% to 60% compared with the conventional industrial method.

Description

A kind of NaY molecular sieve synthesis method that improves single-pot yield

technical field

The invention relates to a synthesis method of NaY molecular sieve. More specifically the present invention relates to a kind of NaY molecular sieve synthesis method that improves single-pot yield.

Background technique

As a catalyst active component or catalyst carrier, Y-type molecular sieve is widely used in refining and chemical processes such as catalytic cracking, hydrocracking and isomerization, and is currently the most used zeolite material. The NaY molecular sieve used as the raw material of the petroleum cracking catalyst is generally required to have a silicon-alumina ratio greater than 5.0 in order to maintain sufficient hydrothermal stability during use. At present, the industrial production of NaY zeolite basically adopts the directing agent method (US3639099, US3671191) proposed by GRACE Company in the United States, that is, under the condition of adding a directing agent, an alkaline silica-alumina gel is first prepared, and then the hydrothermal crystallizing NaY molecular sieve was prepared by chemical method. In the preparation method proposed by USP3639099, due to the high alkalinity of the feed, the silicon-alumina ratio of the prepared NaY molecular sieve is generally 4.0 to 4.5; and when a lower alkalinity is used to improve the silicon-alumina ratio, the water content is low and the colloid is relatively high. Viscous and difficult to stir. Therefore, GRACE Company improved this method in US3671191, namely increasing the feeding silicon-aluminum ratio and increasing the feeding water amount to obtain NaY products with a silicon-aluminum ratio greater than 5.0. Currently, this method is mostly used in industry. However, in order to avoid the problem of being sticky and difficult to stir when the silica-alumina source is gelled, the water content of the system is still relatively high, so that the single-pot yield of the product is low, generally only about 10%.

Therefore, how to reduce the input water of the synthesis system to improve the single-pot yield of NaY molecular sieve synthesis and reduce the energy consumption in the synthesis process has become the direction of people's efforts.

CN1185996A discloses a method for improving the synthesis efficiency of NaY molecular sieve. The method increases the temperature of the raw water glass, reduces the viscosity of the colloid during the gel preparation process, reduces the amount of water input, and improves the single-pot yield. However, the preparation process of this method is relatively complicated, and the operation difficulty and preparation cost are increased.

SUMMARY OF THE INVENTION

The inventors found that the silica-alumina gel system forms gel at a relatively high alkalinity and has a low viscosity, and it can smoothly gel without adding water to reduce the viscosity, which can improve the single-pot yield. Based on this, the present invention is formed.

The purpose of the present invention is to aim at the deficiencies of the prior art, and to provide a NaY molecular sieve synthesis method that is different from the prior art and improves the yield of the single-pot relatively simply.

Therefore, the present invention provides a method for synthesizing NaY molecular sieves with improved single-pot yield, characterized in that the method comprises: a gel obtained by increasing the Na ₂ O/SiO ₂ molar ratio in the precursor of NaY molecular sieves by 5% to 60% Mixture A is stirred at room temperature for at least 0.1 hour to obtain gel mixture B, adding inorganic acid to obtain gel mixture C, and gel mixture C is hydrothermally crystallized and the product is recovered, wherein the precursor of the NaY molecular sieve is composed of a directing agent and a directing agent. It is obtained by mixing water glass, aluminate, aluminum salt and water. In the precursor of the NaY molecular sieve, in terms of moles, Na ₂ O: SiO ₂ =0.2-0.45, SiO ₂ : Al ₂ O ₃ =5-18, _H2O : Al2O3=100～200.

The method of the invention eliminates the viscosity-reducing water that needs to be added when preparing the silica-alumina gel, increases the solid content of the synthetic gel (the solid content of the gel reaches 20% to 30%), and can make the single-pot yield of the synthetic NaY molecular sieve. The rate is 40% to 60% higher than that of conventional industrial methods. That is, under the conditions of optimized SiO ₂ /Al ₂ O ₃ ratio and Na ₂ O/SiO ₂ ratio, the method can adjust the relative content of aluminum sulfate and sodium metaaluminate, so that the precursor of NaY molecular sieve is higher than the usual control. The Na ₂ O/SiO ₂ specific alkalinity will form a gel, and then the excess alkali will be neutralized with an inorganic acid to restore the system to the required Na ₂ O/SiO ₂ specific alkalinity, and then the synthetic gel will be directly Methods NaY molecular sieve can be obtained by heating and crystallization.

The method of the invention, on the premise of not changing the existing industrial equipment, improves the existing synthesis process and uses the conventional industrial raw materials to prepare the NaY molecular sieve, and the single-pot yield is improved. At the same time, the method can save the energy consumption during the crystallization at elevated temperature.

Description of drawings

Fig. 1 is the XRD spectrum of NaY molecular sieve synthesized by the present invention.

Fig. 2 is the scanning (SEM) electron microscope photograph of NaY molecular sieve synthesized by the present invention.

Detailed ways

A method for synthesizing NaY molecular sieves with improved single-pot yield, characterized in that the method comprises: increasing the Na2O/ _SiO2 molar ratio in the precursor of NaY molecular sieves by ₅ % to 60% at room temperature of a gel mixture A obtained by Stir for at least 0.1 hour to obtain gel mixture B, add mineral acid to obtain gel mixture C, gel mixture C is hydrothermally crystallized and the product is recovered, wherein the precursor of the NaY molecular sieve is composed of a directing agent, water glass, aluminum In the precursor of NaY molecular sieve, in terms of moles, Na ₂ O: SiO ₂ =0.2-0.45, SiO ₂ : Al ₂ O ₃ =5-18, H ₂ O: Al ₂ O ₃ =100-200.

In the present invention, the precursor of the NaY molecular sieve is obtained by uniformly mixing the crystallization directing agent with water glass, aluminate and aluminum salt. The crystallization directing agent is prepared according to the prior art (US3639099 and US3671191). It can be silicon source, aluminum source, lye solution and deionized water according to the molar ratio of (15-18) Na ₂ O : Al ₂ O ₃ : (15-17) SiO ₂ : (280-380) H ₂ O After mixing and stirring evenly, it is obtained by standing and aging at room temperature to 70°C for 0.5 to 48 hours. In the precursor of NaY molecular sieve, the content of Al ₂ O ₃ in the directing agent accounts for 3% to 10% of the total amount of Al ₂ O ₃ in the precursor of NaY molecular sieve, preferably 4% to 9%; preparing the directing agent The silicon source used is water glass, the aluminum source is sodium metaaluminate, and the lye solution is sodium hydroxide solution.

In the precursor of the NaY molecular sieve, in terms of moles, Na ₂ O: SiO ₂ =0.2-0.45, SiO ₂ : Al ₂ O ₃ =5-18, H ₂ O: Al ₂ O ₃ =100-200, Under the preferred conditions, Na ₂ O: SiO ₂ =0.25-0.35, SiO ₂ : Al ₂ O ₃ =6-10, H ₂ O:Al ₂ O ₃ =120-180. In the precursor of the NaY molecular sieve, the aluminum source can be one or several mixtures of aluminum sulfate, aluminum chloride, aluminum nitrate or aluminum phosphate.

In the present invention, the gel mixture A can adjust the system basicity of the gel mixture A by adjusting the dosage of the acidic aluminum salt and the basic aluminum salt according to the proportioning requirements, so that the system can be formed at a higher basicity. glue. In order to achieve the goal of increasing the molar ratio of Na ₂ O/SiO ₂ in the precursor of NaY molecular sieve by 5% to 60% according to the present invention, the technical means that can usually be adopted is to adjust the relative content of aluminate and aluminum salt. , to obtain the gel mixture A.

In the present invention, the inorganic acid added to the gel mixture B is used to neutralize the excess alkali in the system, so that the basicity of the gel mixture C can reach the required controlled Na ₂ O/SiO ₂ ratio, such as the precursor of NaY molecular sieve. the same Na ₂ O/SiO ₂ ratio. The inorganic acid can be concentrated sulfuric acid, concentrated hydrochloric acid, concentrated nitric acid, concentrated phosphoric acid or their respective aqueous solutions, among which concentrated sulfuric acid is preferred.

In the present invention, the gel mixture C is crystallized at 70°C to 120°C, preferably at 90°C to 105°C, and the crystallization time is 10h to 50h. The process of recovering the product is well known to those skilled in the art and will not be repeated here. It usually includes the process of obtaining the NaY molecular sieve through filtration, washing and drying after the hydrothermal crystallization is completed. For example, the drying process can be carried out in an oven at 80° C. to 150° C. for 8 to 24 hours, or by flash drying.

The NaY molecular sieve synthesized by the method provided by the invention has a crystallinity of more than 85%, a framework silicon-aluminum ratio of more than 5.0, and a grain size of 500nm-800nm.

The following examples will further illustrate the present invention, but do not limit the content of the present invention.

In the examples, the crystallinity of the synthesized NaY molecular sieves was measured by the RIPP 146-90 standard method.

The skeleton silicon-alumina ratio was determined using the following formula:

SiO ₂ /Al ₂ O ₃ =2×(25.8575-a ₀ )/(a ₀ -24.191), wherein a ₀ is the unit cell parameter of the molecular sieve, which is determined by the RIPP 145-90 standard method. The RIPP standard method mentioned here can be found in "Petrochemical Analysis Methods", edited by Yang Cuiding et al., 1990 edition.

The scanning (SEM) electron microscope analysis of NaY molecular sieve was carried out on the ISI-60A electron microscope of ISI company in the United States. Test conditions: acceleration voltage 20kV, sample inclination angle 30°.

The directing agent used in Examples and Comparative Examples was prepared by the following process: put 629 water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) into a beaker, Add 469g of high alkali sodium metaaluminate (provided by Qilu Catalyst Company, Al ₂ O ₃ 41g/L, Na ₂ O 297g/L, density 1353g/L) under vigorous stirring, and stand at 30°C for aging for 18 hours to obtain guide agent. The molar ratio of the directing agent is 16.4Na ₂ O :Al ₂ O ₃ :15SiO ₂ :326H ₂ O.

Example 1

This example illustrates the synthetic method provided by the present invention.

Add 59g of directing agent and 50g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ to 350g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 82g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, The density of 1416g/L) was mixed uniformly to obtain the gel mixture A with the feed ratio SiO ₂ /Al ₂ O ₃ =8.5 and Na ₂ O/SiO ₂ =0.494, and the gel mixture B was obtained after stirring for 0.5h. 23 g of concentrated sulfuric acid was added to the gel compound B, and the stirring was continued for 0.5 h to obtain a mixture with a charging ratio of SiO ₂ /Al ₂ O ₃ =8.5, Na ₂ O/SiO ₂ =0.310, and H ₂ O/Al ₂ O ₃ =137 Gel mix C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 100 °C for 26 h. The crystallized product was filtered, washed, and dried in an oven at 120 °C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.7%. The XRD spectrum of the molecular sieve is shown in Figure 1, indicating that it is a NaY molecular sieve, the crystallinity is 95.7%, and the framework silicon-aluminum ratio is 5.6. The scanning (SEM) electron microscope photo is shown in Figure 2, and it can be seen that the molecular sieve grain size is concentrated in 500nm-800nm.

Example 2

This example illustrates the synthetic method provided by the present invention.

54g of directing agent and 55g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ ) were added to 320 g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring. 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 70g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, The density of 1416g/L) was mixed uniformly to obtain a gel mixture A with a charging ratio of SiO ₂ /Al ₂ O ₃ =8.5 and Na ₂ O/SiO ₂ =0.464. Gel mixture B was obtained after stirring for 0.5 h. 17.6 g of concentrated sulfuric acid was added to the gel compound B, and the stirring was continued for 0.5 h to obtain the charging ratio of SiO ₂ /Al ₂ O ₃ =8.5, Na ₂ O/SiO ₂ =0.310, and H ₂ O/Al ₂ O ₃ =147 The gel mixture C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 98°C for 29h. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.5%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 94.4%, the skeleton Si-Al ratio is 5.6, and the grain size is concentrated in 500nm-800nm.

Example 3

This example illustrates the synthetic method provided by the present invention.

To 304g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring state, 51.4g of directing agent and 61g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 62g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L , the density is 1416g/L), and the mixture is uniformly mixed to obtain a gel mixture A with a feed ratio of SiO ₂ /Al ₂ O ₃ =8.5 and Na ₂ O/SiO ₂ =0.434. Gel mixture B was obtained after stirring for 0.5 h. 13.5 g of concentrated sulfuric acid was added to the gel compound B, and the stirring was continued for 0.5 h to obtain the charging ratio of SiO ₂ /Al ₂ O ₃ =8.5, Na ₂ O/SiO ₂ =0.310, and H ₂ O/Al ₂ O ₃ =149 The gel mixture C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 90°C for 35 hours. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.3%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 93.8%, the skeleton silicon-alumina ratio is 5.6, and the grain size is concentrated in 500nm-800nm.

Example 4

This example illustrates the synthetic method provided by the present invention.

To 336g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring state, 47.5g of directing agent and 36g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 68g low-alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L , the density is 1416g/L), and the mixture is uniformly mixed to obtain a gel mixture A with a feed ratio of SiO ₂ /Al ₂ O ₃ =10.0 and Na ₂ O/SiO ₂ =0.477. Gel mixture B was obtained after stirring for 0.5 h. 17.5 g of concentrated sulfuric acid was added to the gel compound B, and the stirring was continued for 0.5 h to obtain the feeding ratios of SiO ₂ /Al ₂ O ₃ =10.0, Na ₂ O/SiO ₂ =0.330, and H ₂ O/Al ₂ O ₃ =156 The gel mixture C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 98°C for 29h. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 14.5%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 92.2%, the skeleton Si-Al ratio is 5.7, and the grain size is concentrated in 500nm-800nm.

Example 5

This example illustrates the synthetic method provided by the present invention.

To 268g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring state, 38g of directing agent and 37g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ ) were added in turn. 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 50g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, The density of 1416g/L) was uniformly mixed to obtain a gel mixture A with a feed ratio of SiO ₂ /Al ₂ O ₃ =10.0 and Na ₂ O/SiO ₂ =0.445. Gel mixture B was obtained after stirring for 0.5 h. 10.9 g of concentrated sulfuric acid was added to the gel compound B, and the stirring was continued for 0.5 h to obtain the charging ratio of SiO ₂ /Al ₂ O ₃ =10.0, Na ₂ O/SiO ₂ =0.330, and H ₂ O/Al ₂ O ₃ =159 The gel mixture C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 95°C for 33 hours. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 14.7%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 91.3%, the skeleton Si-Al ratio is 5.7, and the grain size is concentrated in 500nm-800nm.

Example 6

This example illustrates the synthetic method provided by the present invention.

To 248g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L), 52g of directing agent and 105g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ ) were sequentially added under stirring. 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 40g low-alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, The density of 1416g/L) was uniformly mixed to obtain a gel mixture A with a charging ratio of SiO ₂ /Al ₂ O ₃ =7.0 and Na ₂ O/SiO ₂ =0.287. Gel mixture B was obtained after stirring for 0.5 h. 7g of dilute sulfuric acid with a concentration of 30% was added to the gel compound B, and the stirring was continued for 0.5h to obtain the feeding ratio of SiO ₂ /Al ₂ O ₃ =7.0, Na ₂ O/SiO ₂ =0.264, H ₂ O/Al ₂ O ₃ = 136 gel mixture C. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 98°C for 29h. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.4%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 98.0%, the skeleton silicon-alumina ratio is 5.2, and the grain size is concentrated in 500nm-800nm.

Example 7

This example illustrates the synthetic method provided by the present invention.

To 284g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring, 59.3g of directing agent and 112g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 50g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L , the density is 1416g/L), and the mixture is uniformly mixed to obtain a gel mixture A with a feed ratio of SiO ₂ /Al ₂ O ₃ =7.0 and Na ₂ O/SiO ₂ =0.316. Gel mixture B was obtained after stirring for 0.5 h. 18g of dilute sulfuric acid with a concentration of 30% was added to the gel compound B, and the stirring was continued for 0.5h to obtain the feeding ratio of SiO ₂ /Al ₂ O3=7.0, Na ₂ O/SiO ₂ =0.264, H ₂ O/Al ₂ O ₃ Gel Mix C of =134. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 98°C for 29h. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.5%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 96.6%, the skeleton Si-Al ratio is 5.2, and the grain size is concentrated in 500nm～800nm.

Example 8

This example illustrates the synthetic method provided by the present invention.

56.5g of directing agent and 100g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O) were added to 270g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) under stirring. ₃ 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 51g low-alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L , the density is 1416g/L), and the mixture is evenly mixed to obtain a gel mixture A with a feed ratio of SiO ₂ /Al ₂ O ₃ =7.0 and Na ₂ O/SiO ₂ =0.341. Gel mixture B was obtained after stirring for 0.5 h. 25.3 g of dilute sulfuric acid with a concentration of 30% was added to the gel compound B, and the stirring was continued for 0.5 h to obtain the feeding ratio of SiO ₂ /Al ₂ O ₃ =7.0, Na ₂ O/SiO ₂ =0.264, and H2O/Al ₂ O ₃ Gel Mix C of =132. The obtained gel mixture C was directly put into a stainless steel reactor and crystallized at 98°C for 29h. The crystallized product was filtered, washed, and dried in an oven at 120°C overnight to obtain NaY molecular sieves.

The single-pot yield was 15.7%. The molecular sieve XRD pattern and scanning (SEM) electron microscope photograph have the characteristics of Figure 1 and Figure 2, respectively. The crystallinity of NaY molecular sieve is 97.3%, the skeleton Si-Al ratio is 5.2, and the grain size is concentrated in 500nm～800nm.

Comparative Example 1

This comparative example illustrates the effect of synthesizing NaY molecular sieve by conventional industrial gel method (refer to US3671191).

To 182g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L), 31g of directing agent and 59g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ ) were sequentially added under stirring. 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 26g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, The density of 1416g/L) and 95g of water were mixed uniformly to obtain a gel mixture with a feed ratio of SiO ₂ /Al ₂ O ₃ =8.5, Na ₂ O/SiO ₂ =0.310, and H ₂ O/Al ₂ O ₃ =222. The obtained gel mixture was put into a stainless steel reaction kettle and crystallized at 100 °C for 29 h. The crystallized product was filtered, washed, and dried in an oven at 120 °C overnight to obtain NaY molecular sieves.

The single-pot yield was 10.0%. The crystallinity of NaY molecular sieve is 90.5%, and the framework silicon-alumina ratio is 5.3.

It can be seen from Comparative Example 1 that the single-pot yield of NaY molecular sieve prepared by conventional industrial gel method is low.

Comparative Example 2

This comparative example illustrates the effect of synthesizing NaY molecular sieve by conventional industrial gel method (refer to US3671191).

To 318g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L), 45g of directing agent and 79g of aluminum sulfate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ ) were sequentially added under stirring. 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 41g low alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na2O 283.3g/L, density 1416g /L) and 90 g of water were mixed uniformly to obtain a gel mixture with a feed ratio of SiO ₂ /Al ₂ O ₃ =10.0, Na ₂ O/SiO ₂ =0.330, and H ₂ O/Al ₂ O ₃ =216. The obtained gel mixture was put into a stainless steel reaction kettle and crystallized at 100 °C for 29 h. The crystallized product was filtered, washed, and dried in an oven at 120 °C overnight to obtain NaY molecular sieves.

The single-pot yield was 9.6%. The crystallinity of NaY molecular sieve is 90.5%, and the framework silicon-alumina ratio is 5.7.

It can also be seen from Comparative Example 2 that the single-pot yield of NaY molecular sieve prepared by conventional industrial gel method is low.

Comparative Example 3

This comparative example illustrates the effect of synthesizing NaY molecular sieve with reference to CN1185996A.

197g of water glass (provided by Qilu Catalyst Company, SiO ₂ 250.6g/L, modulus 3.36, density 1258g/L) was heated to 65°C, and then 41g of directing agent and 91g of aluminum sulfate solution (Qilu catalyst) were added to it in turn under stirring. Provided by the company, Al ₂ O ₃ 89.7g/L, H ₂ SO ₄ 259g/L, density 1277g/L), 28g low-alkali sodium metaaluminate solution (provided by Qilu Catalyst Company, Al ₂ O ₃ 190.7g/L, Na ₂ O 283.3g/L, density 1416g/L) and 90g of water were mixed uniformly to obtain the ratio of SiO ₂ /Al ₂ O ₃ =7.0, Na ₂ O/SiO ₂ =0.249, H ₂ O/Al ₂ O ₃ = 186 gel mix. The obtained gel mixture was put into a stainless steel reaction kettle and crystallized at 100 °C for 29 h. The crystallized product was filtered, washed, and dried in an oven at 120 °C overnight to obtain NaY molecular sieves.

The single-pot yield was 12.6%. The crystallinity of NaY molecular sieve is 89.5%, and the framework silicon-alumina ratio is 5.0.

As can be seen from Comparative Example 3, although the single-pot yield of NaY molecular sieve prepared by this method is improved compared with the conventional industrial gel method, the silica-alumina of NaY product is relatively low, and the raw material water glass needs to be heated to a certain temperature before gelling , increasing the production cost and operation difficulty.

Claims (9)

1. A synthetic method for improving the yield of a NaY molecular sieve single kettle is characterized by comprising the following steps: na in precursor of NaY molecular sieve₂O/SiO₂Stirring the gel mixture A obtained by increasing the molar ratio by 5-60% for at least 0.1 hour at normal temperature to obtain a gel mixture B, adding an inorganic acid to obtain a gel mixture C, carrying out hydrothermal crystallization on the gel mixture C, and recovering a product, wherein a precursor of the NaY molecular sieve is prepared from a guiding agent, water glass and an aluminateSalt, aluminum salt and water, wherein Na is the precursor of the NaY molecular sieve in terms of mole₂O：SiO₂＝0.2～0.45、SiO₂：Al₂O₃＝5～18、H₂O：Al₂O₃＝100～200。

2. The method of claim 1 wherein the precursor of the NaY molecular sieve is formed by mixing the directing agent with water glass, aluminate, and aluminum salt.

3. The method of claim 1 wherein said precursor of NaY molecular sieve is Na on a molar basis₂O：SiO₂＝0.25～0.35、SiO₂：Al₂O₃＝6～10、H₂O：Al₂O₃＝120～180。

4. The process of claim 1 wherein said aluminate is sodium metaaluminate; the aluminum salt is one or a mixture of aluminum sulfate, aluminum chloride, aluminum nitrate or aluminum phosphate, and preferably aluminum sulfate.

5. The method of claim 1 wherein said directing agent comprises Al₂O₃The content of (A) is Al in the precursor of the NaY molecular sieve₂O₃3 to 10%, preferably 4 to 9% of the total amount.

6. The method according to claim 1 or 5, wherein the directing agent is prepared by mixing a silicon source, an aluminum source, an alkali solution and deionized water according to (15-18) Na₂O:Al₂O₃:(15～17)SiO₂:(280～380)H₂Mixing the components according to the molar ratio of O, uniformly stirring, standing and aging for 0.5-48 hours at the temperature of room temperature to 70 ℃ to obtain the product.

7. The method according to claim 1, wherein the amount of the inorganic acid is such that Na is present in the gel mixture C on a molar basis₂O：SiO₂＝0.2～0.35。

8. A process according to claim 1 or 7, wherein the mineral acid is sulfuric acid.

9. The method according to claim 1, wherein said hydrothermal crystallization is carried out at 90 ℃ to 105 ℃ for 10 hours to 50 hours.

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