A method for preparing hydrogen-type RUT molecular sieve

Abstract

The present application relates to a kind of preparation hydrogen type RUT molecular sieve method, belong to zeolite molecular sieve synthesis technical field.The method includes the following steps: (1) tetraethyl orthosilicate, aluminum isopropyl alcohol, diethyl dimethyl ammonium hydroxide and water are fully mixed and stirred, the mixture is heated to carry out temperature dealcoholization treatment under stirring condition, after dealcoholization is completed, sol mixture is obtained;(2) the sol mixture prepared is loaded into crystallization kettle and heated to carry out hydrothermal treatment, and gel is obtained;(3) the obtained gel is added with water and diethyl dimethyl ammonium hydroxide, then it is ground by grinder and is ground, then it is loaded into crystallization kettle again and heated to carry out hydrothermal crystallization, after crystallization is completed, the obtained crystallization product is carried out solid-liquid separation, the obtained solid product is washed with deionized water, then it is dried, calcined, and hydrogen type RUT molecular sieve is obtained.The present application has simple operation, less synthesis steps, short time, does not use toxic tetramethylammonium hydroxide and fluoride, and has high application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of zeolite molecular sieve synthesis, and more particularly to a method for preparing hydrogen-type RUT molecular sieve. BACKGROUND

[0002] RUT-type molecular sieve is a microporous molecular sieve with small pore channels, and its silicon-aluminum ratio is usually between 10 and 75. The hydrogen-type RUT molecular sieve has high activity and selectivity in xylene isomerization reaction. The RUT-type molecular sieve is usually hydrothermally synthesized under the condition of using tetramethylammonium hydroxide as an organic structure directing agent (Zeolites 1990, 10 (7), 642-649.), and the synthesis condition is harsh, the crystallization time is long (7-12 days), and the tetramethylammonium hydroxide used has great toxicity.

[0003] Researchers have also tried to improve the synthesis method under different conditions. The synthesis method in the document (Zeolites 1994, 14 (8), 675-681.) is to first dissolve tetramethylammonium chloride and ammonium fluoride in water, and then add aluminum oxide and silicon dioxide sources in combination or separately under stirring, and then transfer to a reaction kettle for crystallization at 170℃ for 5 days. However, the product obtained by this method has poor crystallinity and is easy to contain other impurities. The document (Microporous and mesoporous materials 2001, 43 (3), 329-340.) hydrothermally converts FAU zeolite as a crystalline silicon / aluminum source under the condition of using tetramethylammonium hydroxide as a template agent, to obtain RUT zeolite with high crystallinity and purity, and the formation crystallization speed of the RUT zeolite is obviously accelerated. The document (Microporous and Mesoporous Materials 2008, 113 (1-3), 56-63.) synthesizes a full-silicon member of the RUT-type material series, silicon RUB-10, in a SiO2 / H2O / tetrahydro-pyrrole / NH4F system by using tetrahydro-pyrrole as a structure directing agent. The RUT-type material is formed in the presence of tetrahydro-pyrrole, and the high content of tetrahydro-pyrrole is considered to be a key factor for forming the RUT-type structure.

[0004] The structure directing agent tetramethylammonium hydroxide used in the synthesis of RUT molecular sieve has great toxicity and corrosivity to human skin and eyes, has a high mortality rate, and releases toxic gases when decomposed at high temperature. The use of ammonium fluoride as an auxiliary agent will produce wastewater containing fluorine, which is harmful to the environment. In addition, the preparation of RUT-type molecular sieve usually requires a long crystallization time and has low preparation efficiency. SUMMARY

[0005] The application provides a method for preparing hydrogen type RUT molecular sieve, which overcomes the defects of the prior art, and uses low-toxicity and environment-friendly dimethyl diethyl ammonium hydroxide to replace tetramethyl ammonium hydroxide used in the synthesis process of the current RUT type molecular sieve.

[0006] To achieve the above object, the technical scheme adopted by the application is:

[0007] A method for preparing hydrogen type RUT molecular sieve comprises the following steps:

[0008] (1) fully mixing and stirring tetraethyl orthosilicate, aluminum isopropoxide, dimethyl diethyl ammonium hydroxide and water, and performing temperature rising dealcoholization treatment on the mixture under stirring, and obtaining a sol mixture after dealcoholization;

[0009] (2) loading the prepared sol mixture into a crystallization kettle to perform hydrothermal treatment, and obtaining a gel;

[0010] (3) adding water and dimethyl diethyl ammonium hydroxide to the obtained gel, and performing grinding treatment by using a grinder, then loading the gel into the crystallization kettle again to perform hydrothermal crystallization, and after crystallization, performing solid-liquid separation on the obtained crystallization product, washing the obtained solid product with deionized water, and then drying and calcining to obtain hydrogen type RUT molecular sieve.

[0011] Further, in the step (1), the molar ratio of tetraethyl orthosilicate, aluminum isopropoxide, dimethyl diethyl ammonium hydroxide and water is tetraethyl orthosilicate: aluminum isopropoxide: dimethyl diethyl ammonium hydroxide: water = 1.0: 0.02-0.08: 0.20-0.40: 10-30.

[0012] Further, in the step (1), the temperature of dealcoholization treatment is 70-80 ℃, and the dealcoholization treatment time is 2-5 hours.

[0013] Further, in the step (1), water needs to be added to the system after dealcoholization treatment, and the molar ratio of water / silicon is 10-30.

[0014] Further, in the step (2), the hydrothermal treatment temperature is 170-190 ℃, and the hydrothermal treatment time is 1-2 days.

[0015] Further, in the step (3), the molar ratio of the added water and dimethyl diethyl ammonium hydroxide to the original silicon material in the gel system is water: dimethyl diethyl ammonium hydroxide: silicon = 5-10: 0.10-0.20: 1.0.

[0016] Further, the grinding process in the step (3) uses 0.6-1.8 mm zirconia ceramic beads as the grinding medium, the grinding rotation speed is 1000-2500 rpm, and the grinding time is 0.5-3 hours.

[0017] Further, the crystallization temperature in the step (3) is 150-170℃, and the crystallization time is 2-3 days.

[0018] Further, after the crystallization is completed in the step (3), the drying temperature is 100-200℃, the drying time is 3-12 hours, the calcination temperature is 500-600℃, and the calcination time is 3-6 hours.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] 1. No toxic tetramethylammonium hydroxide is used as the structure directing agent, and diethyldimethylammonium hydroxide with low toxicity is used, so that the synthesis process is safer.

[0021] 2. No fluoride is used as the auxiliary agent, no fluorine-containing wastewater is generated, and the synthesis process is more environmentally friendly.

[0022] 3. The preparation process requires a short time, and the hydrothermal treatment and hydrothermal crystallization time is only 3-5 days, which is beneficial to improve the preparation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Example 1 of the present application;

[0024] Figure 2 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Example 2 of the present application;

[0025] Figure 3 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Example 3 of the present application;

[0026] Figure 4 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Example 4 of the present application;

[0027] Figure 5 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Comparative Example 1 of the present application;

[0028] Figure 6 XRD spectrum of the hydrogen type RUT molecular sieve sample synthesized in Comparative Example 2 of the present application; DETAILED DESCRIPTION

[0029] The application will be further described in connection with the following examples. The following examples are intended to help understand the application. Those skilled in the art can make some improvements and modifications to the application without departing from the principles of the application.

[0030] In the following examples, when analyzing the prepared hydrogen-type RUT molecular sieve, X-ray powder diffraction (XRD) was used for phase analysis, inductively coupled plasma emission spectroscopy (ICP-OES) was used to measure the content of silicon and aluminum elements to calculate the silicon-aluminum ratio, and organic alkali titration method was used to measure the B acid concentration (H + ion concentration). Example 1

[0031] A method for preparing a hydrogen-type RUT molecular sieve, using tetraethyl orthosilicate as a silicon source, aluminum isopropoxide as an aluminum source, and diethyl dimethyl ammonium hydroxide as a structure directing agent. The specific synthesis operation is carried out according to the following steps:

[0032] Firstly, 12.03 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) was added to 17.95 grams of water, stirred for 5 minutes, and then 14.60 grams of tetraethyl orthosilicate was added under stirring, and stirred for 4-5 hours. Finally, 0.38 grams of aluminum isopropoxide (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.027: 0.36: 21.38) was added, and stirred for 12 hours. After mixing uniformly, it was heated to 75°C in a water bath for 3 hours to remove alcohol, and the ethanol produced by the hydrolysis of tetraethyl orthosilicate and the isopropanol produced by the hydrolysis of aluminum isopropoxide were removed by evaporation, and the water / silicon atom (molar ratio) was supplemented to 21 to obtain a uniform sol mixture;

[0033] Secondly, the sol mixture was transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, and hydrothermally treated at 180°C for 1.5 days. After hydrothermal treatment, the temperature was lowered to room temperature to obtain a gel;

[0034] Thirdly, 5.98 grams of water and 5.15 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) were added to the gel obtained in the second step, and the molar ratio of the newly added water: the newly added diethyl dimethyl ammonium hydroxide: the original silicon material in the gel system was 7.80: 0.15: 1.0. The mixture was loaded into a grinder, 1.0 millimeter zirconia ceramic beads were used as grinding medium, and the mixture was ground at 2000 revolutions per minute for 1 hour. The ground mixture was transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, and crystallized at 160°C for 2 days. After crystallization, the temperature was lowered to room temperature. The crystallization product was removed and centrifuged to collect the solid product. The solid product was washed with deionized water until neutral, and then dried at 120°C for 6 hours and calcined at 550°C for 4 hours to obtain the hydrogen-type RUT molecular sieve.

[0035] The XRD pattern of the obtained sample is shown in the following figure: Figure 1 The sample analysis of the obtained hydrogen type RUT molecular sieve sample shows that the silicon aluminum ratio (Si / Al atomic ratio) of the obtained sample is 35.8, the B acid concentration (H + ion concentration) of the obtained sample is 4.12 x 10 -4 mol / g. Example 2

[0036] A method for preparing a hydrogen type RUT molecular sieve, using tetraethyl orthosilicate as a silicon source, aluminum isopropoxide as an aluminum source, and diethyl dimethyl ammonium hydroxide as a structure directing agent, the specific synthesis operation is carried out according to the following steps:

[0037] Firstly, 13.37 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) is added into 2.60 grams of water, stirred for 5 minutes, 14.60 grams of tetraethyl orthosilicate is added under stirring, stirred for 4-5 hours, and finally 0.38 grams of aluminum isopropoxide (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.027: 0.40: 10.01) is added, and stirred for 12 hours; after mixing uniformly, it is heated to 70°C in a water bath for 5 hours to remove alcohol, and the ethanol produced by the hydrolysis of tetraethyl orthosilicate and the isopropyl alcohol produced by the hydrolysis of aluminum isopropoxide are removed by evaporation, and the water / silicon atom (molar ratio) is supplemented to 10 to obtain a uniform sol mixture;

[0038] Secondly, the sol mixture is transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 170°C, and hydrothermally treated for 2 days, and then cooled to room temperature to obtain a gel;

[0039] Thirdly, 10.11 grams of water and 3.35 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) are added to the gel obtained in the second step, and the molar ratio of the newly added water: the newly added diethyl dimethyl ammonium hydroxide: the original silicon material in the gel system is 10.00: 0.10: 1.0, the mixture is loaded into a grinder, 1.8 millimeter zirconia ceramic beads are used as grinding medium, and the mixture is ground at 1000 revolutions per minute for 3 hours, the ground mixture is transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 170°C, and crystallized for 2 days, and then cooled to room temperature; the crystallization product is taken out, centrifuged to collect the solid product, washed with deionized water until neutral, dried at 120°C, and calcined at 550°C to obtain a hydrogen type RUT molecular sieve.

[0040] The XRD pattern of the obtained sample is shown in the following figure: Figure 2 The sample analysis of the obtained hydrogen type RUT molecular sieve sample shows that the silicon aluminum ratio (Si / Al atomic ratio) of the obtained sample is 35.3, the B acid concentration (H +The ion concentration) is 4.20 x 10 -4 mol / g. Example 3

[0041] A method for preparing a hydrogen type RUT molecular sieve, using tetraethyl orthosilicate as a silicon source, aluminum isopropoxide as an aluminum source, and diethyl dimethyl ammonium hydroxide as a structure directing agent, the specific synthesis operation is carried out according to the following steps:

[0042] Firstly, 6.70 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) is added into 32.83 grams of water, stirred for 5 minutes, 14.60 grams of tetraethyl orthosilicate is added under stirring, stirred for 4-5 hours, and finally 0.29 grams of aluminum isopropoxide (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.02: 0.20: 30.00) is added, and stirred for 12 hours; after being uniformly mixed, it is heated to 80°C in a water bath for dealcoholization for 2 hours, and ethanol generated by hydrolysis of tetraethyl orthosilicate and isopropyl alcohol generated by hydrolysis of aluminum isopropoxide are removed by evaporation, and water is added to the water / silicon atom (molar ratio) to 30, to obtain a uniform sol mixture;

[0043] Secondly, the sol mixture is transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 190°C for hydrothermal treatment for 1 day, and after the hydrothermal treatment is completed, it is cooled to room temperature to obtain a gel;

[0044] Thirdly, 1.30 grams of water and 6.70 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) are added to the gel obtained in the second step, and the molar ratio of the newly added water: the newly added diethyl dimethyl ammonium hydroxide: the original silicon material in the gel system is 5.01: 0.20: 1.0, the mixture is loaded into a grinder, 0.6 millimeter zirconia ceramic beads are used as grinding medium, and the mixture is ground at 2500 revolutions per minute for 0.5 hours, the ground mixture is transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 150°C for crystallization for 3 days, and after the crystallization is completed, it is cooled to room temperature; the crystallization product is taken out, centrifuged to collect the solid product, washed with deionized water until neutral, and dried at 100°C for 12 hours, and calcined at 600°C for 3 hours to obtain the hydrogen type RUT molecular sieve.

[0045] The XRD pattern of the obtained sample is shown in the following figure: Figure 3 The sample analysis of the obtained hydrogen type RUT molecular sieve sample shows that the silicon aluminum ratio (Si / Al atomic ratio) of the obtained sample is 49.0, and the B acid concentration (H + ion concentration) of the obtained sample is 3.26 x 10 -4 mol / g. Example 4

[0046] A method for preparing hydrogen type RUT molecular sieve, using tetraethyl orthosilicate as silicon source, aluminum isopropoxide as aluminum source, diethyl dimethyl ammonium hydroxide as structure directing agent, the specific synthesis operation is carried out according to the following steps:

[0047] Firstly, 12.03 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) was added into 17.95 grams of water, stirred for 5 minutes, 14.60 grams of tetraethyl orthosilicate was added under stirring, stirred for 4-5 hours, finally 1.14 grams of aluminum isopropoxide was added (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.08: 0.36: 21.38), stirred for 12 hours; after mixing uniformly, heated to 75℃ in water bath for 3 hours to remove alcohol, evaporated to remove ethanol produced by tetraethyl orthosilicate hydrolysis and isopropyl alcohol produced by aluminum isopropoxide hydrolysis, and supplemented with water to a water / silicon atom (molar ratio) of 21, to obtain a uniform sol mixture;

[0048] Secondly, the sol mixture was transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 180℃ for hydrothermal treatment for 1.5 days, cooled to room temperature after hydrothermal treatment was completed, to obtain a gel;

[0049] Thirdly, 5.98 grams of water and 5.15 grams of diethyl dimethyl ammonium hydroxide aqueous solution (25% mass fraction) were added to the gel obtained in the second step, the molar ratio of the newly added water: the newly added diethyl dimethyl ammonium hydroxide: the original silicon material in the gel system was 7.80: 0.15: 1.0, the mixture was loaded into a grinder, 1.0 millimeter zirconia ceramic beads were used as grinding medium, and the mixture was ground at 2000 revolutions per minute for 1 hour, the ground mixture was transferred to a closed stainless steel kettle with a polytetrafluoroethylene liner, heated to 160℃ for crystallization for 2 days, cooled to room temperature after crystallization was completed; the crystallization product was taken out, centrifuged to collect the solid product, washed with deionized water until neutral, dried at 200℃ for 3 hours, and calcined at 500℃ for 6 hours, to obtain the hydrogen type RUT molecular sieve.

[0050] The XRD pattern of the obtained sample is shown in the following figure: Figure 4 The sample analysis of the obtained hydrogen type RUT molecular sieve sample shows that the silicon aluminum ratio (Si / Al atomic ratio) of the obtained sample is 15.6, the B acid concentration (H + ion concentration) of the obtained sample is 9.78×10 -4 mol / g. Comparative Example 1

[0051] A method for preparing hydrogen type RUT molecular sieve, using tetraethyl orthosilicate as silicon source, aluminum isopropoxide as aluminum source, diethyl dimethyl ammonium hydroxide as structure directing agent, the specific synthesis operation is carried out according to the following steps:

[0052] First step, add 17.18 g of diethyl dimethyl ammonium hydroxide aqueous solution (mass fraction 25%) into 23.93 g of water, stir for 5 minutes, add 14.60 g of tetraethyl orthosilicate under stirring, stir for 4-5 hours, finally add 0.38 g of aluminum isopropoxide (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.027: 0.51: 29.18), stir for 12 hours; after mixing uniformly, heat to 75°C in a water bath for dealcoholization for 3 hours, evaporate ethanol produced by hydrolysis of tetraethyl orthosilicate and isopropyl alcohol produced by hydrolysis of aluminum isopropoxide, and supplement water to water / silicon atom (molar ratio) 29, to obtain a uniform sol mixture;

[0053] Second step, transfer the sol mixture to a closed stainless steel kettle with a polytetrafluoroethylene liner, heat to 180°C for hydrothermal treatment for 1.5 days, then cool to 160°C for crystallization for 2 days, after crystallization, cool to room temperature; remove the crystallization product, centrifuge to collect the solid product, wash with deionized water until neutral, dry at 120°C for 6 hours, and calcine at 550°C for 4 hours to obtain a solid sample. The XRD pattern of the obtained sample is shown in the following figure, it can be seen that the main component is amorphous species. Figure 5 Comparative example 2

[0054] Use tetraethyl orthosilicate as a silicon source, aluminum isopropoxide as an aluminum source, and diethyl dimethyl ammonium hydroxide as a structure directing agent, and the specific synthesis operation is carried out according to the following steps:

[0055] First step, add 17.18 g of diethyl dimethyl ammonium hydroxide aqueous solution (mass fraction 25%) into 23.93 g of water, stir for 5 minutes, add 14.60 g of tetraethyl orthosilicate under stirring, stir for 4-5 hours, finally add 0.38 g of aluminum isopropoxide (tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.027: 0.51: 29.18), stir for 12 hours; after mixing uniformly, heat to 75°C in a water bath for dealcoholization for 3 hours, evaporate ethanol produced by hydrolysis of tetraethyl orthosilicate and isopropyl alcohol produced by hydrolysis of aluminum isopropoxide, and supplement water to water / silicon atom (molar ratio) 29, to obtain a uniform sol mixture;

[0056] Second step, transfer the sol mixture to a closed stainless steel kettle with a polytetrafluoroethylene liner, heat to 180°C for hydrothermal treatment for 1.5 days, then cool to 160°C for crystallization for 2 days, after crystallization, cool to room temperature; remove the crystallization product, centrifuge to collect the solid product, wash with deionized water until neutral, dry at 120°C for 6 hours, and calcine at 550°C for 4 hours to obtain a solid sample. The XRD pattern of the obtained sample is shown in the following figure, it can be seen that the main component is amorphous species. Figure 6

[0057] ​​While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a hydrogen form RUT molecular sieve, characterized by, The method comprises the following steps: (1) fully mixing and stirring tetraethyl orthosilicate, aluminum isopropoxide, diethyl dimethyl ammonium hydroxide and water according to the molar ratio of tetraethyl orthosilicate: aluminum isopropoxide: diethyl dimethyl ammonium hydroxide: water = 1.0: 0.02-0.08: 0.20-0.40: 10-30, and performing temperature rising dealcoholization treatment on the mixture under stirring; and obtaining a sol mixture after dealcoholization; (2) loading the prepared sol mixture into a crystallization kettle and performing hydrothermal treatment, wherein the hydrothermal treatment temperature is 170-190 ℃, and the hydrothermal treatment time is 1-2 days, to obtain a gel; (3) adding water and diethyl dimethyl ammonium hydroxide to the obtained gel and performing grinding treatment with a grinder, wherein the molar ratio of water: diethyl dimethyl ammonium hydroxide: silicon in the gel system is 5-10: 0.10-0.20: 1.0, then loading the gel into a crystallization kettle again and performing hydrothermal crystallization, wherein the crystallization temperature is 150-170 ℃, and the crystallization time is 2-3 days, and after crystallization, performing solid-liquid separation on the obtained crystallization product, washing the obtained solid product with deionized water, and then drying and calcining to obtain a hydrogen type RUT molecular sieve.

2. The method for preparing hydrogen-form RUT molecular sieves according to claim 1, characterized in that, The temperature of the dealcoholization treatment in step (1) is 70-80 ℃, and the dealcoholization treatment time is 2-5 hours.

3. The method for preparing hydrogen-form RUT molecular sieves according to claim 1, characterized in that, After the dealcoholization treatment in step (1), water needs to be added to the system to a molar ratio of water / silicon of 10-30.

4. The method for preparing hydrogen-form RUT molecular sieves according to claim 1, characterized in that, In step (3), 0.6-1.8 mm zirconia ceramic beads are used as the grinding medium, the grinding speed is 1000-2500 rpm, and the grinding time is 0.5-3 hours.

5. The method for preparing hydrogen-form RUT molecular sieves according to claim 1, characterized in that, After crystallization in step (3), the drying temperature is 100-200 ℃, the drying time is 3-12 hours, the calcination temperature is 500-600 ℃, and the calcination time is 3-6 hours.

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