CN1608987A - Spherical mesoporous molecular sieve with narrow particle size distribution and its prepn - Google Patents

Abstract

The present invention belongs to the field of molecular sieve in inorganic material, and is especially mesoporous MCM-41 molecular sieve and its preparation process. The present invention features that the mesoporous MCM-41 molecular sieve is synthesized under the action of ultrasonic wave and the product has crystallization degree 10-30 % higher than that of MCM-41 molecular sieve synthesized in available technology, round crystal particles of average size of 2 micron, and narrow particle size distribution in 1-4 micron mainly. The preparation process features that the introduction of ultrasonic wave and 30-50 % shorter crystallizing period. The preparation process of mesoporous MCM-41 molecular sieve with CTAB as template agent and TEOS as silicon source includes the steps of: crystallization in acid aqua, filtering, washing, drying, and roasting in the air to eliminate template agent and to obtain MCM-41 molecular sieve.

Description

A kind of mesopore molecular sieve of spherical narrow size distribution and preparation method

One. technical field

The present invention relates to a kind of mesopore molecular sieve and preparation method of spherical narrow size distribution, belong to the molecular sieve field of inorganic materials, be specifically related to MCM-41 mesopore molecular sieve and preparation method.

Two. background technology

1992, the researchist of U.S. Mobil company exists down by quaternary ammonium salt cationic surfactant liquid crystal molecule template, the hydro-thermal reaction of silicon-dioxide is prepared the mesopore molecular sieve that the aperture is 1.5nm～10nm, and its principal character is: the pore passage structure that 1. has rule; 2. pore size distribution is narrow, and pore size can be regulated by changing the tensio-active agent alkyl chain length; 3. through optimizing synthesis condition or aftertreatment, can have good thermostability and certain hydrothermal stability; 4. particle has regular profile, and can keep the duct order of height in micro-meter scale.The appearance of novel mesopore molecular sieve M41S family material, the traditional concept and the limited aperture of zeolite molecular sieve have been broken, make the research and the application of molecular screen material enter a new era, simultaneously also make mesoporous catalytic material of new generation become the research focus of catalysis circle, material circle, caused various countries researchists' great interest.In the novel meso-porous molecular sieve material of this family, MCM-41 arranges because of it has uniform hexagonal hole road, higher thermostability and potential catalytic performance and receive much attention.The performance-adjustable of the pore passage structure of MCM-41 molecular sieve uniqueness and aperture thereof, silica alumina ratio is indicating that this class material has great application prospect aspect the catalytic cracking of organic macromolecule, special compound synthetic.Therefore, this class material still in Application Areas, has all constantly been obtained new progress aspect the study on the modification of no matter synthetic at it, structure, performance since 1992 occur, and in the gap of dwindling gradually between application demand and the performance.

The method of synthetic MCM-41 mesopore molecular sieve has a variety of, and classical synthetic method is the hydrothermal crystallization method under the alkaline condition, and the report of relevant this method is a lot.Huo Qisheng etc. have proposed in the strongly-acid medium method of synthetic MCM-41 mesopore molecular sieve, and this method is the improvement of classical alkaline system synthetic method, synthesis condition become more gentleness and easy handling, and the consumption of tensio-active agent significantly reduces.The characteristics of this method maximum are: the crystallization time and relative low surfactant concentration of strongly-acid medium, low temperature (room temperature can be synthesized), weak point.But the degree of crystallinity of synthetic MCM-41 sample promptly can not improve degree of crystallinity than synthesizing the low relatively of MCM-41 in the alkaline medium in the strongly-acid medium when shortening crystallization time.And its particles dispersed is inhomogeneous, and clustering phenomena is comparatively obvious, and particle diameter big (its grain pattern as shown in Figure 1).

Three. summary of the invention

The mesopore molecular sieve of a kind of spherical narrow size distribution of the present invention and preparation method's purpose be, discloses the technical scheme of the spherical narrow size distribution MCM-41 mesopore molecular sieve of synthetic and preparation method under a kind of ultrasonic wave effect.

A kind of mesopore molecular sieve of spherical narrow size distribution, it is characterized in that the synthetic molecular sieve is the MCM-41 mesopore molecular sieve under the ultrasonic wave effect, product degree of crystallinity improves 10%～30% than prior art synthetic MCM-41 mesopore molecular sieve, crystal grain is regular circle, median size is 2 μ m, narrow diameter distribution concentrates between 1～4 μ m.

The preparation method of above-mentioned molecular sieve is characterized in that pull-in frequency is the ultrasonic wave effect of 20 kHz in the building-up process of MCM-41 molecular sieve, makes the crystallization time of MCM-41 mesopore molecular sieve shorten 30%～50% than prior art.Concrete processing step is:

I. compound concentration is the HCl solution of 2.5～3.5mol/L;

II. under the magnetic agitation effect, be 1.0TEOS: xHCl: yCTAB according to the reaction mass mol ratio: 334 H ₂The O obtain solution, wherein, 18.8＜x＜26.25,0.21＜y＜0.30, order of addition(of ingredients) stops after treating to dissolve fully stirring for add template hexadecyl trimethyl ammonium bromide CTAB earlier in the HCl solution that step I is prepared, and adds tetraethoxy TEOS again in the settled solution of gained;

III. Step II gained mixing solutions is put into ultrasonic cleaner, ultrasonic power output is set at 200～500w, and crystallization 1～4h is with synthetic product filtration, washing, the drying that obtains;

IV. with Step II I gained pressed powder, in air, promptly obtain the MCM-41 mesopore molecular sieve of spherical narrow size distribution in 500～600 ℃ of following roasting 5～8h.

The invention has the advantages that the MCM-41 mesopore molecular sieve of synthetic spherical narrow size distribution under the ultrasonic wave effect, crystallization time shortens 30%～50% than prior art, product degree of crystallinity improves 10%～30% than prior art synthetic MCM-41 mesopore molecular sieve, crystal grain is regular circle, median size is 2 μ m, narrow diameter distribution concentrates between 1～4 μ m.

Four. description of drawings

Fig. 1 is the sem photograph (SEM) by the MCM-41 mesopore molecular sieve of prior art for preparing.

Fig. 2 is the feature X-ray diffractogram (XRD) of embodiment 1 synthetic MCM-41 sample.

Fig. 3 is the sem photograph (SEM) of embodiment 1 synthetic MCM-41 sample.

Five. embodiment

Embodiment 1:

The HCl solution of preparation 3M, measure 360ml, under the even stirring of magnetic stirring apparatus, add 4.5g hexadecyl trimethyl ammonium bromide CTAB, stop after treating to dissolve fully stirring, add 25ml tetraethoxy TEOS, this mixing solutions is placed ultrasonic cleaner, at ultrasonic power output crystallization 2h under the condition of 460w, with synthetic sample filtering, washing, the drying that obtains, dried pressed powder is removed template in 560 ℃ of following roasting 6h in air, promptly obtain the MCM-41 mesopore molecular sieve of spherical narrow size distribution.

Embodiment 2:

The HCl solution of preparation 2.5M, measure 360ml, under the even stirring of magnetic stirring apparatus, add 3.8gCTAB, stop after treating to dissolve fully stirring, add 25ml TEOS, this mixing solutions is placed ultrasonic cleaner, is crystallization 1h under the condition of 220w at ultrasonic power output, sample filtering, washing, the drying that will synthetic obtain, dried pressed powder is removed template in 600 ℃ of following roasting 5h in air, promptly obtain the MCM-41 mesopore molecular sieve of spherical narrow size distribution.

Embodiment 3:

The HCl solution of preparation 3.5M, measure 360ml, under the even stirring of magnetic stirring apparatus, add 5.0gCTAB, stop after treating to dissolve fully stirring, add 20ml TEOS, this mixing solutions is placed ultrasonic cleaner, is crystallization 2h under the condition of 360w at ultrasonic power output, sample filtering, washing, the drying that will synthetic obtain, dried pressed powder is removed template in 530 ℃ of following roasting 8h in air, promptly obtain the MCM-41 mesopore molecular sieve of spherical narrow size distribution.

Claims (2)

1. the mesopore molecular sieve of a spherical narrow size distribution, it is characterized in that be a kind of under the ultrasonic wave effect synthetic MCM-41 mesopore molecular sieve, product degree of crystallinity improves 10%～30% than prior art synthetic MCM-41 mesopore molecular sieve, crystal grain is regular circle, median size is 2 μ m, narrow diameter distribution concentrates between 1～4 μ m.

2. the preparation method of the described molecular sieve of claim 1 is characterized in that pull-in frequency is the ultrasonic wave effect of 20kHz in the building-up process of MCM-41 molecular sieve, and crystallization time shortens 30%～50% than prior art, and concrete processing step is:

I. compound concentration is the HCl solution of 2.5～3.5mol/L;

II. under the magnetic agitation effect, be 1.0TEOS: xHCl: yCTAB:334H according to the reaction mass mol ratio ₂The O obtain solution, wherein, 18.8＜x＜26.25,0.21＜y＜0.30, order of addition(of ingredients) stops after treating to dissolve fully stirring for add template hexadecyl trimethyl ammonium bromide CTAB earlier in the HCl solution of being prepared, and adds tetraethoxy TEOS again in the settled solution of gained;

III. Step II gained mixing solutions is put into ultrasonic cleaner, ultrasonic power output is set at 200～500w, and crystallization 1～4h is with synthetic product filtration, washing, the drying that obtains;

IV. with Step II I gained pressed powder, in air, promptly obtain the MCM-41 mesopore molecular sieve of spherical narrow size distribution in 500～600 ℃ of following roasting 5～8h.

Images