Method for preparing phosphorus-containing Beta molecular sieve and prepared molecular sieve

Abstract

The invention relates to a method for preparing a phosphorus-containing Beta molecular sieve and the prepared molecular sieve, and the method comprises the following steps: a, contacting a phosphorus source, a template agent, an aluminum source, water and an optional alkali source to obtain a first mixture; b, contacting a silicon source with the first mixture to obtain a second mixture; and c, carrying out hydrothermal crystallization treatment on the second mixture, and carrying out heat treatment on a hydrothermal crystallization product. According to the method disclosed by the invention, the phosphorus-containing Beta molecular sieve with a relatively wide range of silica-alumina ratio and a relatively large grain size can be prepared under the condition that a fluorine-containing compound is not used.

Description

Technical Field

[0001] The present disclosure relates to the field of molecular sieve synthesis, and in particular, to a method for preparing a phosphorus-containing Beta molecular sieve and the prepared molecular sieve. Background Art

[0002] Beta molecular sieve was first synthesized by Mobil Corporation of the United States in 1967 using the classic hydrothermal crystallization method (USP3,308,069). The zeolite has a unique three-dimensional (or two-dimensional) pore structure and has high catalytic activity in hydrocracking, hydroisomerization, and heavy oil cracking. After modification or loading of certain metal components, it can be used in oil refining and petrochemical processes such as hydrocracking and hydroisomerization. According to the method disclosed in the patent, the synthesis process of beta zeolite is as follows: a mixture containing Na2O, Al2O3, tetraethylammonium hydroxide (TEAOH), SiO2 and water is made into a slurry and crystallized in an autoclave at 75-200°C for 3-60 days. The molar ratio of the feed in the reaction system is: SiO2 / Al2O3=10-200, Na2O / TEAOH=0.0-0.1, TEAOH / SiO2=0.1-1.0. This method uses silica sol as the silicon source, which has a large water content, resulting in an increase in the amount of template used and a long crystallization time, resulting in low production efficiency of the molecular sieve.

[0003] A large number of scientists have done a lot of research, but there has not yet been a clear, simple method for producing large-grained beta molecular sieves with a wide range of silicon-aluminum ratios. It is reported that some Chinese experts have used fluorides to produce beta molecular sieves with grains of 500nm, but the extremely high requirements of fluorides on production equipment make it almost impossible to overcome the difficulties in the specific implementation of the invention, and it will also cause pollution to the environment. Summary of the invention

[0004] The purpose of the present disclosure is to provide a method for preparing phosphorus-containing Beta molecular sieve and the prepared molecular sieve.

[0005] In order to achieve the above object, the present disclosure provides a method for preparing a phosphorus-containing Beta molecular sieve in a first aspect, the method comprising the following steps:

[0006] a. contacting a phosphorus source, a template, an aluminum source, water, and an optional alkali source to obtain a first mixture;

[0007] b. contacting a silicon source with the first mixture to obtain a second mixture;

[0008] c. subjecting the second mixture to a hydrothermal crystallization treatment, and subjecting the hydrothermal crystallization product to a heat treatment.

[0009] Optionally, the phosphorus source includes one or more of diethyl phosphine oxide, triethyl phosphine oxide, dibutyl phosphine oxide, tributyl phosphine oxide, diphenyl phosphine oxide and triphenyl phosphine oxide;

[0010] The alkali source includes one or more of sodium hydroxide, sodium oxide, potassium hydroxide and potassium oxide;

[0011] The template agent includes one or more of tetraethylammonium hydroxide, n-butylamine, tetraethylammonium bromide and tetraethylammonium chloride;

[0012] The aluminum source includes one or more of sodium aluminate, SB powder, aluminum alcoholate, aluminum oxide, aluminum hydroxide, aluminum sulfate and gibbsite;

[0013] The silicon source includes one or more of silica sol, silicon dioxide, white carbon black, silicate and solid silica gel.

[0014] Optionally, the molar ratio of the template, the aluminum element calculated as Al2O3, the silicon element calculated as SiO2, the water and the alkali metal element calculated as metal oxide is (0.01-0.20): (0.01-0.066): 1: (5-30): (0-0.1), preferably (0.04-0.19): (0.01-0.066): 1: (6-25): (0.01-0.1);

[0015] The molar ratio of phosphorus element calculated as P2O5 to aluminum element calculated as Al2O3 is (0.4-1.5):1, preferably (0.6-1.0):1.

[0016] Optionally, in step c, the conditions of the hydrothermal crystallization treatment include: time of 18-168h and temperature of 140-200°C.

[0017] Optionally, in step c, the heat treatment method includes calcination, and the heat treatment conditions include: time of 0.5-8h and temperature of 400-800°C.

[0018] Optionally, the method further comprises: drying the solid product obtained by the hydrothermal crystallization treatment to obtain the hydrothermal crystallization product.

[0019] The second aspect of the present disclosure provides a phosphorus-containing Beta molecular sieve prepared by the method described in the first aspect of the present disclosure.

[0020] Optionally, the molecular sieve has a crystal size of 0.3-2 μm, preferably 0.35-1.5 μm.

[0021] Optionally, the silicon to aluminum ratio of the molecular sieve is 15-100, preferably 20-60.

[0022] Optionally, on a dry basis, the content of phosphorus in terms of P2O5 is 0.05-3 wt%, preferably 0.08-2 wt%, relative to the total weight of the molecular sieve.

[0023] Through the above technical scheme, the present invention prepares a phosphorus-containing large-grain Beta molecular sieve by adding a phosphorus source during the in-situ synthesis of Beta molecular sieve. The method of the present invention avoids the use of fluorine-containing compounds, and the prepared phosphorus-containing Beta molecular sieve has a wider range of silicon-aluminum ratios and a larger grain size.

[0024] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0026] Figure 1 It is the X-ray diffraction spectrum of Beta molecular sieve A prepared in Example 1 of the present disclosure.

[0027] Figure 2 This is a transmission electron microscope (TEM) image of Beta molecular sieve A prepared in Example 1 of the present disclosure.

[0028] Figure 3 It is a transmission electron microscope (TEM) image of Beta molecular sieve D1 prepared in Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0029] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0030] The first aspect of the present disclosure provides a method for preparing a phosphorus-containing Beta molecular sieve, the method comprising the following steps:

[0031] a. contacting a phosphorus source, a template, an aluminum source, water, and an optional alkali source to obtain a first mixture;

[0032] b. contacting a silicon source with the first mixture to obtain a second mixture;

[0033] c. subjecting the second mixture to a hydrothermal crystallization treatment, and subjecting the hydrothermal crystallization product to a heat treatment.

[0034] According to one embodiment of the present disclosure, the phosphorus source includes phosphorus-containing organic matter, for example, it may include one or more of diethyl phosphine oxide, triethyl phosphine oxide, dibutyl phosphine oxide, tributyl phosphine oxide, diphenyl phosphine oxide and triphenyl phosphine oxide. When the phosphorus source includes more than two substances, there is no specific limitation on their ratio.

[0035] According to one embodiment of the present disclosure, the type of template is conventional in the art, for example, it may include one or more of tetraethylammonium hydroxide, n-butylamine, tetraethylammonium bromide and tetraethylammonium chloride. When the template includes more than two substances, there is no specific restriction on their ratio; the template can be added in the form of an aqueous solution, for example, the present disclosure does not specifically limit the concentration of the aqueous solution, for example, the concentration of the tetrabutylammonium hydroxide aqueous solution can be 15-30% by weight.

[0036] According to an embodiment of the present disclosure, the silicon source includes one or more of silica sol, silicon dioxide, white carbon black, silicate and solid silica gel. When the silicon source includes two or more substances, there is no specific limitation on their ratio.

[0037] According to one embodiment of the present disclosure, the alkali source includes one or more of sodium hydroxide, sodium oxide, potassium hydroxide and potassium oxide. When the alkali source includes two or more substances, there is no specific limitation on their ratio.

[0038] According to one embodiment of the present disclosure, the molar ratio of the template, the aluminum element calculated as Al2O3, the silicon element calculated as SiO2, the water and the alkali metal element calculated as metal oxide is (0.01-0.20): (0.01-0.066): 1: (5-30): (0-0.1), preferably (0.04-0.19): (0.01-0.066): 1: (6-25): (0.01-0.1); wherein the molar amount of "alkali metal element" includes the molar amount of alkali metal elements in all raw materials, for example, using NaOH as the alkali source, sodium aluminate as the aluminum source, tetraethylammonium hydroxide as the template, and solid silica gel as the silicon source, the molar amount of the alkali metal element includes the total molar amount of sodium in sodium aluminate and NaOH, and is calculated as Na2O.

[0039] According to one embodiment of the present disclosure, the molar ratio of phosphorus element calculated as P2O5 to aluminum element calculated as Al2O3 is (0.4-1.5):1, preferably (0.6-1.0):1.

[0040] According to one embodiment of the present disclosure, step a comprises: mixing a phosphorus source, water and an optional alkali source under stirring for 0.1-2 hours, and then mixing the obtained mixture with a template and an aluminum source for 0.5-2 hours.

[0041] According to one embodiment of the present disclosure, step b comprises: contacting the silicon source with the first mixture under stirring for 0.5-2 hours to obtain a second mixture.

[0042] According to one embodiment of the present disclosure, in step c, the hydrothermal crystallization treatment can be carried out in a hydrothermal kettle, and the method and conditions are conventional in the art. For example, the conditions of the hydrothermal crystallization treatment include: time of 18-168h and temperature of 140-200°C.

[0043] According to one embodiment of the present disclosure, in step c, the heat treatment method includes roasting, and the heat treatment conditions include: time is 0.5-8h, temperature is 400-800°C, and the heat treatment can be carried out in an air atmosphere or an oxygen atmosphere, wherein the definitions of air atmosphere and oxygen atmosphere are conventional in the art.

[0044] According to one embodiment of the present disclosure, the method further comprises: drying the solid product obtained by the hydrothermal crystallization treatment to obtain the hydrothermal crystallization product, and the method and conditions for the drying treatment are conventional in the art.

[0045] According to one embodiment of the present disclosure, the method further includes: performing solid-liquid separation on the mixture obtained by hydrothermal crystallization treatment, and washing the obtained solid with water; the solid-liquid separation method may be, for example, filtration, and the water washing method is conventional in the art; further, the liquid containing the template obtained by solid-liquid separation can be used in step b to further reduce costs, and the amount of the liquid containing the template is calculated based on water.

[0046] The second aspect of the present disclosure provides a phosphorus-containing Beta molecular sieve prepared by the method described in the first aspect of the present disclosure.

[0047] According to one embodiment of the present disclosure, the crystal size of the molecular sieve is 0.3-2 μm, preferably 0.35-1.5 μm.

[0048] According to one embodiment of the present disclosure, the silicon-aluminum ratio of the molecular sieve is 15-100, preferably 20-60; the silicon-aluminum ratio refers to the molar ratio of silicon oxide to aluminum oxide in the molecular sieve.

[0049] According to one embodiment of the present disclosure, on a dry basis, the content of phosphorus in terms of P2O5 is 0.05-3 wt%, preferably 0.08-2 wt%, relative to the total weight of the molecular sieve.

[0050] The present invention will be further described below by way of examples, but the contents of the present invention are not limited thereby.

[0051] Unless otherwise specified, the instruments and reagents used in the embodiments of the present invention are commonly used by those skilled in the art.

[0052] The Beta molecular sieve synthesized by the method of Example 1 in USP 3,308,069 was used as a standard sample, and its crystallinity was determined to be 100%.

[0053] The X-ray diffraction spectra were measured on a Rigaku TTR-3 powder X-ray diffractometer with the following instrument parameters: copper target (tube voltage 40 kV, tube current 250 mA), scintillation counter, step width 0.02°, and scanning rate 0.4° / min.

[0054] The crystal size of the molecular sieve was characterized by transmission electron microscopy (TEM) produced by FEI Company.

[0055] The elemental chemical composition of the molecular sieve was determined by X-ray fluorescence method using the GB / T 30905-2014 standard method, and the amount and weight of phosphorus pentoxide, silicon dioxide and aluminum trioxide in the molecular sieve bulk phase were calculated from the analysis results.

[0056] Example 1

[0057] The phosphorus-containing Beta molecular sieve A is prepared by the following steps:

[0058] Add 24.60g of diphenylphosphine oxide and 6.96g of NaOH to 280.59 of deionized water, stir for 0.5h, add 145.69g of tetraethylammonium hydroxide solution (concentration is 25 weight%) and 12.52g of sodium aluminate to the solution and stir for 0.5h to obtain a first mixture; add 200g of solid silica gel (SiO2 content is 77.4 weight%) to the first mixture, stir and disperse at room temperature for 1h, transfer the obtained second mixture to a hydrothermal autoclave, hydrothermally crystallize at 160°C for 60h, dry the hydrothermal crystallization product at 120°C for 12h, and then calcine at 600°C for 2h in an air atmosphere to obtain phosphorus-containing Beta molecular sieve A;

[0059] The molar ratio of tetraethylammonium hydroxide, aluminum calculated as Al2O3, silicon calculated as SiO2, water and NaOH calculated as Na2O is 0.096:0.0295:1:8.39:0.063;

[0060] The molar ratio of phosphorus calculated as P2O5 to aluminum calculated as Al2O3 is 0.797:1;

[0061] The XRD test results of molecular sieve A are as follows: Figure 1 As shown, according to Figure 1 It can be seen that molecular sieve A is Beta molecular sieve; TEM test of molecular sieve A shows the following results: Figure 2 As shown; the parameters of molecular sieve A are listed in Table 1.

[0062] Example 2

[0063] The phosphorus-containing Beta molecular sieve B is prepared by the following steps:

[0064] Add 6.04 g of diethylphosphine oxide and 6.29 g of NaOH to 600 g of deionized water, stir for 0.25 h, add 238.24 g of tetraethylammonium hydroxide solution (concentration of 25 wt%) and 10.82 g of SB powder (alumina content of 67%) to the solution and stir for 0.5 h to obtain a first mixture; add 156 g of white carbon black (SiO2 content of 99 wt%) to the first mixture, stir and disperse at room temperature for 2 h, transfer the obtained second mixture to a hydrothermal autoclave, hydrothermally crystallize at 140° C. for 100 h, dry the hydrothermal crystallization product at 120° C. for 12 h, and then calcine at 650° C. for 3 h in an air atmosphere to obtain phosphorus-containing Beta molecular sieve B;

[0065] The molar ratio of tetraethylammonium hydroxide, aluminum element calculated as Al2O3, silicon element calculated as SiO2, water and sodium element calculated as Na2O is 0.157:0.0276:1:18:0.031;

[0066] The molar ratio of phosphorus calculated as P2O5 to aluminum calculated as Al2O3 is 0.4:1;

[0067] The parameters of molecular sieve B are listed in Table 1.

[0068] XRD test on molecular sieve B shows that it is Beta molecular sieve.

[0069] Example 3

[0070] The phosphorus-containing Beta molecular sieve C is prepared by the following steps:

[0071] Add 6.31 g of triethylphosphine oxide and 0.28 g of NaOH to 90 g of deionized water, stir for 1 hour, add 20.29 g of tetraethylammonium hydroxide solution (concentration of 25 weight %) and 2.62 g of SB powder (alumina content of 67%) to the solution and stir for 0.5 hour to obtain a first mixture; add 69 g of alkaline silica sol (SiO2 content of 30 weight %) to the first mixture, stir and disperse at room temperature for 1 hour, transfer the obtained second mixture to a hydrothermal autoclave, hydrothermally crystallize at 190° C. for 72 hours, dry the hydrothermal crystallization product at 120° C. for 12 hours, and then calcine at 500° C. for 6 hours in an air atmosphere to obtain phosphorus-containing Beta molecular sieve C;

[0072] The molar ratio of tetraethylammonium hydroxide, aluminum element calculated as Al2O3, silicon element calculated as SiO2, water and sodium element calculated as Na2O is 0.1:0.05:1:24.7:0.01;

[0073] The molar ratio of phosphorus calculated as P2O5 to aluminum calculated as Al2O3 is 1.37:1;

[0074] The parameters of molecular sieve C are listed in Table 1.

[0075] XRD test on molecular sieve C shows that it is Beta molecular sieve.

[0076] Example 4

[0077] The phosphorus-containing Beta molecular sieve D is prepared by the following steps:

[0078] 24.26 g of dibutylphosphine oxide and 7.06 g of KOH were added to 390.74 g of deionized water, and the mixture was stirred for 0.25 h. 39.8 g of tetraethylammonium bromide and 11.48 g of SB (alumina content 67%) were added to the solution and stirred for 1.5 h to obtain a first mixture. 150 g of solid silica gel (SiO2 content 77.4 wt%) was added to the first mixture, and the mixture was stirred and dispersed at room temperature for 2 h. The obtained second mixture was transferred to a hydrothermal autoclave, and hydrothermally crystallized at 170° C. for 60 h. The hydrothermally crystallized product was dried at 120° C. for 12 h, and then calcined at 450° C. for 8 h in an air atmosphere to obtain phosphorus-containing Beta molecular sieve D.

[0079] The molar ratio of tetraethylammonium bromide, aluminum element calculated as Al2O3, silicon element calculated as SiO2, water and potassium element calculated as K2O is 0.098:0.039:1:11:0.033;

[0080] The molar ratio of phosphorus element calculated as P2O5 to aluminum element calculated as Al2O3 is 1:1;

[0081] The parameters of molecular sieve D are listed in Table 1.

[0082] XRD test on molecular sieve D shows that it is Beta molecular sieve.

[0083] Example 5

[0084] The phosphorus-containing Beta molecular sieve E was prepared by the following steps:

[0085] Add 7.48 g of diphenylphosphine oxide and 0.16 g of NaOH to 700 g of deionized water, stir for 0.25 h, add 26.38 g of tetraethylammonium hydroxide (concentration of 35 wt%) and 5.50 g of sodium aluminate to the above solution and stir for 0.5 h to obtain a first mixture; add 230 g of solid silica gel (SiO2 content of 77.4 wt%) to the first mixture, stir and disperse at room temperature for 1 h, transfer the obtained second mixture to a hydrothermal autoclave, hydrothermally crystallize at 190° C. for 48 h, dry the hydrothermal crystallization product at 120° C. for 12 h, and then calcine at 450° C. for 6 h in an air atmosphere to obtain phosphorus-containing Beta molecular sieve E;

[0086] The molar ratio of tetraethylammonium hydroxide, aluminum element calculated as Al2O3, silicon element calculated as SiO2, water and sodium element calculated as Na2O is 0.02:0.0121:1:13.4:0.012;

[0087] The molar ratio of phosphorus calculated as P2O5 to aluminum calculated as Al2O3 is 0.55:1;

[0088] The parameters of molecular sieve E are listed in Table 1.

[0089] XRD test on molecular sieve E shows that it is Beta molecular sieve.

[0090] Comparative Example 1

[0091] Beta molecular sieve D1 was prepared by the following steps:

[0092] Add 6.96 g of NaOH to 280.59 g of deionized water and stir for 0.5 h. Add 145.69 g of tetraethylammonium hydroxide solution (concentration of 25 wt%) and 12.52 g of sodium aluminate to the solution and stir for 0.5 h to obtain a first mixture. Add 200 g of solid silica gel (SiO2 content of 77.4 wt%) to the first mixture and stir and disperse at room temperature for 1 h. Transfer the obtained second mixture to a hydrothermal autoclave, crystallize at 160°C for 60 h, dry at 120°C for 12 h, and then calcine at 600°C for 6 h in an air atmosphere to obtain Beta molecular sieve D1. The parameters of molecular sieve D1 are listed in Table 1.

[0093] The TEM test results of molecular sieve D1 are as follows: Figure 3 shown.

[0094] XRD test on molecular sieve D1 shows that it is Beta molecular sieve.

[0095] Table 1

[0096]

[0097]

[0098] According to the above data, it can be seen that the phosphorus-containing Beta molecular sieve prepared by the method disclosed in the present invention has a wider range of silicon-aluminum ratio and a larger grain size.

[0099] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0101] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing phosphorus-containing Beta molecular sieve, characterized in that: The method comprises the following steps: a. contacting a phosphorus source, a template, an aluminum source, water, and an optional alkali source to obtain a first mixture; b. contacting a silicon source with the first mixture to obtain a second mixture; c. subjecting the second mixture to a hydrothermal crystallization treatment, and subjecting the hydrothermal crystallization product to a heat treatment.

2. The method according to claim 1, wherein: The phosphorus source includes one or more of diethyl phosphine oxide, triethyl phosphine oxide, dibutyl phosphine oxide, tributyl phosphine oxide, diphenyl phosphine oxide and triphenyl phosphine oxide; The alkali source includes one or more of sodium hydroxide, sodium oxide, potassium hydroxide and potassium oxide; The template agent includes one or more of tetraethylammonium hydroxide, n-butylamine, tetraethylammonium bromide and tetraethylammonium chloride; The aluminum source includes one or more of sodium aluminate, SB powder, aluminum alcoholate, aluminum oxide, aluminum hydroxide, aluminum sulfate and gibbsite; The silicon source includes one or more of silica sol, silicon dioxide, white carbon black, silicate and solid silica gel.

3. The method according to claim 1, wherein: The molar ratio of the template, the aluminum element calculated as Al2O3, the silicon element calculated as SiO2, the water and the alkali metal element calculated as metal oxide is (0.01-0.20): (0.01-0.066): 1: (5-30): (0-0.1), preferably (0.04-0.19): (0.01-0.066): 1: (6-25): (0.01-0.1); The molar ratio of phosphorus element calculated as P2O5 to aluminum element calculated as Al2O3 is (0.4-1.5):1, preferably (0.6-1.0):

1.

4. The method according to claim 1, wherein: In step c, the conditions of the hydrothermal crystallization treatment include: time of 18-168h and temperature of 140-200°C.

5. The method according to claim 1, wherein: In step c, the heat treatment method includes roasting, and the heat treatment conditions include: time is 0.5-8h, and temperature is 400-800°C.

6. The method according to claim 1, wherein: The method further comprises: drying the solid product obtained by the hydrothermal crystallization treatment to obtain the hydrothermal crystallization product.

7. The phosphorus-containing Beta molecular sieve prepared by the method described in any one of claims 1 to 6.

8. The phosphorus-containing Beta molecular sieve according to claim 7, wherein: The crystal size of the molecular sieve is 0.3-2 μm, preferably 0.35-1.5 μm.

9. The phosphorus-containing Beta molecular sieve according to claim 7, wherein: The silicon to aluminum ratio of the molecular sieve is 15-100, preferably 20-60.

10. The phosphorus-containing Beta molecular sieve according to claim 7, wherein: On a dry basis, the content of phosphorus in terms of P2O5 is 0.05-3% by weight, preferably 0.08-2% by weight, relative to the total weight of the molecular sieve.

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