Cubic-phase mesoporous silico-aluminate hollow ball of a kind of hydrothermally stable and preparation method thereof
Technical field
The present invention relates to a kind of cubic-phase mesoporous silico-aluminate hollow ball and novel preparation method of hydrothermally stable, relate to a kind of cubic-phase mesoporous silico-aluminate hollow ball and preparation method thereof or rather, belong to mesoporous materials field with superelevation hydrothermal stability.
Background technology
The regulation of pure according to the world in applied chemistry federation (IUPAC), mesoporous material refers to the inorganic porous material of aperture in the 1.5nm-50.0nm scope.The scientist of U.S. Mobil company in 1992 at first reports, formed the silico-aluminate meso-porous molecular sieve material of a class formation novelty by the self-assembly effect of organic and inorganic component in solution, this material is owing to have ordered arrangement duct and the extremely narrow pore size distribution of aperture about 3nm, break through at one stroke the restriction of the pore diameter range of zeolite molecular sieve material, made the absorption that much in zeolite molecular sieve, is difficult to the large volume molecule finished, separate, especially the heavy-oil hydrogenation in catalyzed reaction such as the petrochemical complex, olefinic polymerization, macromole is selected the possibility that becomes of catalysis etc.Therefore, ordered mesoporous material is rapidly with its regular adjustable pore passage structure, high specific surface area and good thermostability and become multi-disciplinary research focuses such as domestic and international material, physics, biology.
Compare with the micro-pore zeolite molecular sieve, though mesoporous material has bigger duct, can be applied to catalysis, the separation of macromolecular substance, but its heat and hydrothermal stability but can not satisfy the requirement of general catalyzed reaction far away, this has directly limited its application in catalyzed reaction, and this also is the mesoporous material key point that can not be applied very soon up to now.Have only the heat and the hydrothermal stability of mesoporous material to be improved, its advantage than poromerics just can demonstrate fully out.Recently, synthetic more existing reports of the mesoporous material of relevant high stability.X.Zhao etc. (J.Phy.Chem.B, 1998,102,7371) reported once that Silanization reaction reduced the concentration of duct internal surface-OH group and makes duct internal surface hydrophobic improve the stability of MCM-41 in water.R.Mokaya etc. (Angew.Chem.Int.Ed.Engl.1999,38,2930.) improve the hydrothermal stability of MCM-41 with the method for aftertreatment (repeat crystallization or with MCM-41 silicon source).J.Pinnavaia (J.Am.Chem.Soc., 2000,122,8791), S.Kaliaguine (Angew.Chem.Int.Ed.Engl., 2001,40,3248) and Xiao (J.Am.Chem.Soc., 2001,123,5014) etc. all be that raw material is by introducing the hydrothermal stability that the mesoporous inorganic body of wall improves mesoporous material with zeolite structured unit with the zeolite seed crystal.But above-mentioned report all concentrates on the MCM-41 of six side's phases with one-dimensional tunnel structure.Yet the research of the hydrothermal stability of relevant cube of phase MCM-48 does not but appear in the newspapers so far.Compare with MCM-41, MCM-48 has the three-dimensional open-framework that interconnection intersects, and this more helps the material molecule diffusion transport of portion within it, so the MCM-48 of synthesizing high-stability has more practical significance.
At numerous areas such as catalysis, separation and transmitters, the morphological structure of mesoporous material is all had certain specific requirement, so morphology control also is an important branch in the mesoporous material research.Discover that the pattern of mesoporous material is varied, as hexagonal prism shape, volution, sphere etc., shell is that mesoporous hollow ball then has more wide application prospect at aspects such as catalysis, medicament slow release and sustained release.Though the report of this respect is arranged in the recent period, as H.Lin, J.Pinnavaia and S.Schacht etc. all reported the synthetic of mesoporous tube-in-tube, hollow ball and hollow vesica with hollow structure on Science, but the meso-hole structure in tube wall or the spherical shell is one dimension six sides and arranges, and mesoporous duct be latitude directional ring along ball around spherical shell, be unfavorable for the transmission that guest molecule is outside outside in or from the lining.So far, the synthetic of the cubic-phase mesoporous hollow ball with 3 D pore canal of relevant high hydrothermal stability do not appear in the newspapers.In the present invention, the mesoporous material that we will prepare high stability combines with the method for its morphology control, and under the booster action that does not need other organic additives, not only made the cubic-phase mesoporous material that has than high hydrothermal stability, and realized effective control to its pattern.
Summary of the invention
The object of the present invention is to provide a kind of cubic-phase mesoporous silico-aluminate hollow ball material with three-dimensional open-framework and simple preparation method thereof with superelevation hydrothermal stability high-sequential.Cubic-phase mesoporous hollow ball material provided by the invention, the steady time in boiling water was above 120 hours.
The preparation process of the cubic-phase mesoporous hollow ball with superelevation hydrothermal stability provided by the invention as shown in Figure 1.Comment as follows with regard to its main process below:
(1) with silicon source (as TEOS) and aluminium source (as AlCl
3Or Al
2(SO
4)
3) with deionized water according to (0.1-2) Al
2O
3: (90-150) SiO
2: (3000-6600) H
2The mixed of O under agitation makes homogeneous latex emulsion.
(2) with alkali source (as NaOH) and template (as TPAOH or TPABr) and deionized water according to (20-30) Na
2O: (8-20) TPA: (3000-6600) H
2The ratio uniform mixing of O slowly splashes in the emulsion of above-mentioned vigorous stirring under certain temperature (10-25 ℃).And under the gel room temperature, wore out 12 hours, make the precursor of micro-pore zeolite ZSM-5.Here the hydrolysis temperature in silicon source has directly determined the whether hollow of mesoporous ball, and stirring velocity (500-1500rpm) is then being controlled the hollow diameter of final mesoporous ball.This also is one of key of difference of the present invention and prior art.
(3) with certain amount of surfactant (as hexadecyl methyl brometo de amonio) according to (8-16) CTAB: (6000-10000) H
2The ratio of O is dissolved in deionized water and makes surfactant soln, under the normal temperature zeolite precursor thing is mixed with it then, and lasting the stirring is made synthesising mesoporous molten Ji liquid in 2 hours.Here, surfactant concentration only is the 1/6-1/4 of the traditional cubic-phase mesoporous material producing method of bibliographical information.
(4) the hydrothermal crystallizing temperature of synthesising mesoporous solution is 130-150 ℃, treatment time 24-44 hour, effectively control hydrothermal temperature and reaction times are one of gordian techniquies of the cubic-phase mesoporous material of preparation high-sequential, and can guarantee that the secondary structure unit of ZSM-5 zeolite is introduced into mesoporous inorganic wall and does not separate out the crystallite that forms micropore.
According to suitable prescription, the hydrolysis temperature and the stirring velocity in control silicon source, and under suitable hydrothermal condition according to above-mentioned operational path, made cubic-phase mesoporous hollow ball with three-dimensional open-framework, median size is about 500nm, the diameter of hollow parts is about 150-200nm, the about 200-250nm of ball wall thickness, and the secondary structure unit of ZSM-5 zeolite successfully introduced mesoporous inorganic wall.Hydrothermal treatment consists finds that this material has very high stability, boil 120 hours as boiling water after, the hollow ball particle is still complete, mesoporous pore structure high-sequential, specific surface area (759m
2/ g) preceding (1005m is handled in maintenance
2/ g) 75%.High-resolution-ration transmission electric-lens is observed the section of this sample and is found that this material is the ball of hollow.Infrared spectra shows that mesoporous body of wall contains the secondary structure unit of ZSM-5 zeolite.Silicon source hydrolysis temperature difference in the experiment, then the final appearance structure of material is also different.Can crystallization temperature and time then directly have influence on the secondary structure unit of micro-pore zeolite and introduce mesoporous inorganic wall, and have determined the hydrothermal stability and the order of material.
The major advantage of cubic-phase mesoporous silico-aluminate hollow ball with superelevation hydrothermal stability provided by the invention and preparation method thereof is:
(1) preparation process is simple: do not adopt traditional first hydrothermal crystallizing to prepare zeolite seed crystal, and then form mesoporous material with the tensio-active agent self-assembly, but adopt suitable colloidal sol proportioning in sol system, directly to generate the secondary structure unit of zeolite, both guarantee the high-sequential of structured material, improved its hydrothermal stability again.
(2) do not adopt other organic additives or polyethylene ball to wait the vacancy that forms mesoporous ball in this preparation process, but form the template of vacancy by the non-complete hydrolysis in silicon source under the certain temperature, the silicon source is continued hydrolysis and is formed the spheroidal particle of hollow behind the elevated temperature.
(3) this cubic-phase mesoporous hollow ball with superelevation hydrothermal stability is that wide prospect has been opened up in the practical application of mesoporous material, not only is expected to be used for controlled delivery of pharmaceutical agents and discharges, and also can be used for the processes such as catalysis, separation under the hydrothermal condition.
Description of drawings
Preparation technology's flow process of the cubic-phase mesoporous silico-aluminate hollow ball of Fig. 1 high stability provided by the invention.
Fig. 2 is according to (a) of the hollow ball of Fig. 1 prepared scanning and (b) transmission electron microscope photo.
The high power transmission electron microscope photo of the cubic-phase mesoporous hollow ball of Fig. 3 and the electron diffraction spot in corresponding constituency: (a) [100] direction; (b) [311] direction; (c) section [110] direction; (d) hydrothermal treatment consists [110] direction after 120 hours.
The XRD spectra of the cubic-phase mesoporous silico-aluminate hollow ball of Fig. 4 high stability before and after hydrothermal treatment consists: (a) (illustration: the angle of elevation XRD spectra before the hydrothermal treatment consists) before the boiling water treating; (b) after the boiling water treating.
The XRD spectra of different hydrolysis temperatures of Fig. 5 TEOS and different gel aging temperature gained materials.
(a) TEOS hydrolysis temperature 10-25 ℃, the gel aged at room temperature
(b) the TEOS hydrolysis temperature is 30 ℃, the gel aged at room temperature
(c) TEOS hydrolysis temperature 10-25 ℃, 50 ℃ of gels are aging
Fig. 6 TEOS30 ℃ of following hydrolysis, the high power transmission electron microscope photo of the final mesoporous material of gel aged at room temperature gained and the electron diffraction spot in corresponding constituency illustrate that the cubic-phase mesoporous material of synthetic is not hollow.
The XRD spectra of the different hydrothermal crystallizing temperature of Fig. 7 gained material: (a) 110 ℃; (b) 140 ℃; (c) 160 ℃.
The IR spectrogram of common MCM-48 of Fig. 8 (a) and the cubic-phase mesoporous silico-aluminate hollow ball of (b) provided by the invention high stability.
Embodiment
Embodiment 1: with silicon source (TEOS), aluminium source (Al
2(SO
4)
3), alkali source (NaOH), template (TPAOH) and deionized water be according to Al
2O
3: 100SiO
2: 20Na
2O: 10TPA
+: 10000H
2The ratio of O (mol ratio) is at 10-25 ℃ of following forerunner's colloidal sol of configuration micro-pore zeolite, after the aged at room temperature with tensio-active agent (12CTAB: 10000H
2O) aqueous solution stirs 2h, and 140 ℃ of hydrothermal crystallizing 48h after the filtration drying roasting, promptly get the cubic-phase mesoporous silico-aluminate hollow ball of high stability.Its spheroidal particle as shown in Figure 2, the spherical shell meso-hole structure is shown in Fig. 2 (a) and (b), (c).Hydrothermal treatment consists 120h in boiling water then, its high power transmission electron microscope photo and XRD spectra are respectively shown in Fig. 2 (d) and Fig. 3 (b).Embodiment 2: basic recipe is constant, only changes the hydrolysis temperature in silicon source in the micro-pore zeolite colloidal sol preparation process and the aging temperature of colloidal sol, obtains following several different embodiments:
(a) TEOS hydrolysis temperature 10-25 ℃, the gel aged at room temperature
(b) the TEOS hydrolysis temperature is 30 ℃, the gel aged at room temperature
(c) TEOS hydrolysis temperature 10-25 ℃, 50 ℃ of gels are aging
The XRD spectra of the material that makes respectively as shown in Figure 5.
As can be seen, under suitable prescription, certain TEOS hydrolysis temperature and colloidal sol aging temperature are to the synthetic crucial effects that plays of ordered mesoporous material.30 ℃ of cubic-phase mesoporous materials of following hydrolysis institute's synthetic of TEOS are not hollow structures, as shown in Figure 6.As seen, TEOS10-25 ℃ of hydrolysis, the gel aged at room temperature is best synthesis condition.
Embodiment 3: basic recipe, hydrolysis temperature and aging temperature are constant, only change crystallization temperature, and the XRD spectra of gained material as shown in Figure 7.
110℃;(b)140℃;(c)160℃
As can be seen, hydrothermal crystallizing temperature low excessively (110 ℃) then can not form the mesoporous material of high-sequential, and hydrothermal crystallizing temperature higher (160 ℃), then there is the crystal grain of micro-pore zeolite to separate out, forms mesoporous and mixture micropore from mesoporous body of wall, but not the mixture of the two.
The hydrothermal stability of the table 1 pair mesoporous material that different embodiments make compares, synthetic MCM-48 hydrothermal stability is the poorest according to the conventional method as can be seen, boiling water treating 24h, its orderly pore structure is promptly by completely destroy, and increase by the more traditional MCM-48 of the non-hollow material hydrothermal stability of embodiment 2 (b) synthetic, but order promptly descends much after the 72h hydrothermal treatment consists.The cubic-phase mesoporous ball with hollow structure that we are made then behind boiling water treating 120h, still keeps higher specific surface and narrow pore size distribution, illustrates that it has the hydrothermal stability of superelevation, can satisfy the requirement of general catalyzed reaction fully.
Physical properties before and after the different mesoporous material hydrothermal treatment consists of table 1 relatively
| S
Before(m
2/g)
| D
Before(nm)
| ?T(h) | S
After(m
2/g)
| D
After(nm)
|
MCM-48 | ?1040 | ?3.2 | ?24 | ?289 | ?/ |
CMCM-48 | ?1267 | ?3.1 | ?48 | ?368 | ?6.8 |
HSCM | ?1005 | ?2.9 | ?120 | ?759 | ?3.5 |