CN101177277A

CN101177277A - Rapid synthesis method of nano molecular sieve beta

Info

Publication number: CN101177277A
Application number: CNA200710150794XA
Authority: CN
Inventors: 黄震; 苏峻峰
Original assignee: Tianjin University of Commerce
Current assignee: Tianjin University of Commerce
Priority date: 2007-12-07
Filing date: 2007-12-07
Publication date: 2008-05-14

Abstract

The invention discloses a quick synthetic method of nanometer molecular sieve beta, which comprises the following steps: de-ionized water solution is added in aluminum source, and then organic template reagent water solution is added in; high specific surface area silicon source is added in the solution; the mixture is put in a reaction kettle and heated to 165 to 175 DEG C for hydrothermal crystallization for 9 to 96 hours, and then is cooled to ambient temperature to obtain crystallization production; the molar ratio of the reactant is 0.5 to 3.0 Na2O : 1.0 Al2O3 : 15 to 60 SiO2 : 2.0 to 20.0 TEAOH : 80 to 350 H2O. With the application of high specific surface area silicon oxide powder, higher crystallization temperature and reactant with better compatibility, the synthesis method of the invention obviously improves the mass transfer velocity of the reactant in the mixture and shortens the synthetic time of molecular sieve beta.

Description

The fast synthesis method of nano molecular sieve beta

Technical field

The present invention relates to a kind of method that adopts hydrothermal method quickly synthesizing nano molecular sieve beta.

Background technology

Molecular sieve beta be have intermediate pore size (

) three-dimensional pore passage structure, have catalysis and the separation function of selecting shape and screening, as the epoxidation of alkene, the acetylize of naphthalene, aromatic alkylation, the hydroxylation of aldehyde ketone, the reactions such as isomerization of heptane, hexanaphthene and benzene, C ₆-C ₈The separation of isomer, separating etc. of the separation of organism/water and various mixed gass demonstrates excellent economic value and social effect at petrochemical industry.

Molecular sieve beta is successfully made by hydrothermal method in 1967 by Wadlinger etc. at first, and its alkaline synthetic medium is made up of tetraethyl ammonium hydroxide and alkali metal cation.A main difficult problem that runs in the building-up process of molecular sieve beta is that its synthetic yield and product degree of crystallinity are not too high, and particularly its repeatability is relatively poor, generated time is long, often needs several days even several week.Wherein, it is more to influence the crystalline factor, and principal element has the nucleation induction time of this molecular sieve long partially, and used silicon source is solid silica or the silicon sol or the organosilicon material of low surface area, and the synthetic temperature is on the low side a bit.Report with the fluorochemical to be the crystal seed method (Kim etc. of media though have recently, Micropor.Mesopor.Mater., 2004,68,77-82) or dried glue high temperature fumigation and steaming method (Matsukata etc., Micropor.Mesopor.Mater., 2002,56,1-10) can shorten crystallization time greatly, but its synthesis step is numerous and diverse, and process is wayward, is difficult to mass production.

Summary of the invention

The present invention is in order to overcome weak point of the prior art, to provide a kind of synthesis cycle short, the synthetic method of the nano molecular sieve beta that synthetic yield and product degree of crystallinity are high.

The present invention is achieved through the following technical solutions:

A kind of fast synthesis method of nano molecular sieve beta is characterized in that, comprises the steps:

(1) in container, put into the aluminium source after, add deionized water, be stirred to dissolving, dissolution time was generally 20-60 minute; Add the organic formwork agent aqueous solution then, stir;

(2) in above-mentioned solution, slowly add the silicon source, stir; Churning time was generally 2-5 hour.

(3) said mixture is put into hydrothermal reaction kettle, be heated to 165-175 ℃ of hydrothermal crystallization 9-96 hour, be cooled to room temperature then, obtain crystallized product;

(4) product that obtains of crystallization washs according to the method for routine, centrifugation, and drying, roasting just obtains the molecular sieve beta powder particle.

Above-mentioned reactant aluminium source is water miscible sodium aluminate or sodium metaaluminate, and the silicon source is the silicon oxide that specific surface area is higher than 300 meters squared per gram, comprises silica gel 60, fumed silica 380 or other silicon oxide.Organic formwork agent is the commercially available tetraethyl ammonium hydroxide aqueous solution, and can select its mass percent concentration for use is 35-40%, and the mole proportioning of described reactant is 0.5-3.0 Na ₂O: 1.0Al ₂O ₃: 15-60SiO ₂: 2.0-20.0TEAOH: 80-350 H ₂O.The optimum molar proportioning of described reactant is 1.5 Na ₂O: 1.0 Al ₂O ₃: 30 SiO ₂: 10.0 TEAOH: 250 H ₂O.

The present invention has following technique effect:

The silicon oxide powder of synthetic method of the present invention by using high specific area, higher Tc and matching reactant are preferably formed, make the mass transfer velocity of reactant in mixing liquid be able to obvious raising, thereby shorten crystal nucleation inductive phase, accelerate crystal nucleation and growth velocity.Form a large amount of nucleus earlier, constantly be three-dimensional growth then and form small crystal, the footpath is the high pineapple fruit shape particle of 300nm, narrow diameter distribution and degree of crystallinity because of template effect boundling forms all together between small crystal.The generated time of molecular sieve beta obviously shortens, and can finish whole crystallisation process in 9-96 hour.

Description of drawings

Fig. 1 is the fate map that the XRD spectra of molecular sieve beta changed with the reaction times; Wherein transverse axis is 2 θ angle of diffraction, and the longitudinal axis is a diffracted intensity, and the diffracted intensity height promptly shows the degree of crystallinity height.

Fig. 2 amplifies 10000 times SEM photo for molecular sieve beta;

Fig. 3 amplifies 50000 times SEM photo for molecular sieve beta.

Embodiment

Below in conjunction with specific embodiment to the detailed description of the invention.

Embodiment 1

Take by weighing 1.082 gram sodium aluminate powder (Na2O, 47.7wt%, Na with beaker ₂O/Al ₂O ₃Mol ratio is 1.5) after, adding 12.70 restrains deionized water dissolvings, stirs extremely to dissolve in 20 minutes to obtain settled solution.Adding the 20.45 gram tetraethyl ammonium hydroxide 40wt% aqueous solution then, continue to mix 10 minutes to evenly, is 10.0 gram specific surface areas that the silica gel 60 of 500 meters squared per gram slowly adds and continued mechanical stirring 3 hours again.The silicon sol of gained is put into the stainless steel sealed reactor that has teflon lined, under 170 ℃ of autogenous pressures crystallization 7-96 hour.Be cooled to room temperature with cold water then, obtain the crystalline product.Product that crystallization obtains is through washing, and centrifugation after the drying, 550 ℃ of roastings 8 hours, obtains molecular sieve beta, its X-ray powder diffraction spectrum as shown in Figure 1, its scanning electron microscope result and Fig. 2 and Fig. 3 are similar.

Table 1 is depicted as degree of crystallinity, productive rate, specific surface area and the pore volume of molecular sieve beta among the embodiment data with the crystallization time variation.

Table 1

Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)
Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)	SG-1 SG-2 SG-3 SG-4 SG-5 SG-6	7 9 12 24 48 96	31 89 91 93 96 100	8.6 10.2 9.9 10.1 9.8 10.2	240 495 653 569 678 657	0.17 0.28 0.27 0.29 0.31 0.39

The crystallization time of SG-1 sample is 7 hours in the above-mentioned table, and crystallization is incomplete, and the molecular sieve Beta degree of crystallinity of gained is lower, and its specific surface area is all less with total pore volume.

Embodiment 2

Take by weighing 1.770 gram sodium aluminate powder (Na2O, 23.3wt%, Na with beaker ₂O/Al ₂O ₃Mol ratio is 0.5) after, adding 10.91 restrains deionized water dissolvings, stirs extremely to dissolve in 40 minutes to obtain settled solution.Adding the 11.20 gram tetraethyl ammonium hydroxide 35wt% aqueous solution then, continue to mix 10 minutes to evenly, is 12.0 gram specific surface areas that the fumed silica of 350 meters squared per gram slowly adds and continued mechanical stirring 2 hours again.The silicon sol of gained is put into the stainless steel sealed reactor that has teflon lined, under 175 ℃ of autogenous pressures crystallization 9-96 hour.Be cooled to room temperature with cold water then, obtain the crystalline product.The product that crystallization obtains is through washing, and centrifugation after the drying, 550 ℃ of roastings 8 hours, obtains molecular sieve beta, and its X-ray powder diffraction spectrum and Fig. 1 are similar, and its scanning electron microscope result and Fig. 2 and Fig. 3 are similar.

Table 2 is depicted as degree of crystallinity, productive rate, specific surface area and the pore volume of molecular sieve beta among the embodiment data with the crystallization time variation.

Table 2

Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)
Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)	FS-1 FS-2 FS-3 FS-4 FS-5	9 24 12 36 96	90 94 91 95 98	9.8 9.6 10.1 9.9 9.7	606 583 532 596 656	0.26 0.33 0.32 0.30 0.35

Embodiment 3

Take by weighing 3.994 gram sodium aluminate powder (Na with beaker ₂O, 64.6wt%, Na ₂O/Al ₂O ₃Mol ratio is 3.0) after, adding 26.10 restrains deionized water dissolvings, stirs extremely to dissolve in 60 minutes to obtain settled solution.Adding the 102.13 gram tetraethyl ammonium hydroxide 40wt% aqueous solution then, continue to mix 10 minutes to evenly, is 50.0 gram specific surface areas that the silica gel 40 of 400 meters squared per gram slowly adds and continued mechanical stirring 5 hours again.The silicon sol of gained is put into the stainless steel sealed reactor that has teflon lined, under 165 ℃ of autogenous pressures crystallization 9-96 hour.Be cooled to room temperature with cold water then, obtain the crystalline product.Product that crystallization obtains is through washing, and centrifugation after the drying, 550 ℃ of roastings 8 hours, obtains molecular sieve beta, its X-ray powder diffraction spectrum as shown in Figure 1, its scanning electron microscope result and Fig. 2 are similar.

Table 3 is depicted as degree of crystallinity, productive rate, specific surface area and the pore volume of molecular sieve beta in the case study on implementation data with the crystallization time variation.

Table 3

Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)
Sample	Crystallization time (hr)	Degree of crystallinity (%)	Productive rate (g solid)	Specific surface area (m ²/g)	Total pore volume (cm ³/g)	SG-7 SG-8 SG-9 SG-10 SG-11 SG-12	9 18 24 36 48 96	94 98 95 96 98 99	50.2 52.1 51.4 49.8 50.6 51.6	468 654 598 632 616 675	0.29 0.28 0.33 0.32 0.35 0.37

Although the disclosed fast synthesis method that relates to a kind of nano molecular sieve beta has been carried out special description with reference to embodiment, embodiment described above is illustrative and not restrictive, under the situation that does not break away from the spirit and scope of the present invention, all variations and modification are all within the scope of the present invention.

Claims

1. the fast synthesis method of a nano molecular sieve beta is characterized in that, comprises the steps:

(1) in container, put into the aluminium source after, add deionized water, be stirred to dissolving; Add the organic formwork agent aqueous solution then, stir;

(2) in above-mentioned solution, slowly add the silicon source, stir;

(4) product that obtains of crystallization is through washing, centrifugation, and drying, roasting just obtains molecular sieve be ta powder particle;

Above-mentioned reactant aluminium source is water miscible sodium aluminate or sodium metaaluminate, and the silicon source is the silicon oxide that specific surface area is higher than 300 meters squared per gram, and organic formwork agent is the tetraethyl ammonium hydroxide aqueous solution, and the mole proportioning of described reactant is 0.5-3.0Na ₂O: 1.0Al ₂O ₃: 15-60SiO ₂: 2.0-20.0TEAOH: 80-350H ₂O.

2. the fast synthesis method of nano molecular sieve beta according to claim 1, the mole proportioning that it is characterized in that described reactant is 1.5Na ₂O: 1.0 Al ₂O ₃: 30 SiO ₂: 10.0 TEAOH: 250H ₂O.