阅读说明：本技术 一种新结构二氧化硅沸石 (Novel structure silicon dioxide zeolite ) 是由 龙英才 沈威 于 2019-09-03 设计创作，主要内容包括：本发明提出一种新结构二氧化硅沸石其化学组成的二氧化硅与三氧化二铝的摩尔比大于2000、具有特征粉末XRD衍射谱,结构中的二种孔道开口孔径分别为4.4x5.6A和5.1x5.7A,所述沸石的BET表面积大于350m<Sup>2</Sup>/g,所述沸石的微孔容积大于0.20ml/g。本发明提出的硅沸石-3是将以高纯气相白炭黑或正硅酸乙酯水热反应合成的前驱体硅沸石-1在一定的气氛中500℃以上焙烧一定时间通过晶格严重收缩生成的,其具有特定的孔道形状以及孔道开口,其生成过程条件简单易实现,无任何废水废气排放。(The invention provides a new structure of silicon dioxide zeolite, the mole ratio of silicon dioxide and aluminium oxide in its chemical composition is greater than 2000, and it has characteristic powder XRD diffraction spectrum, and the opening aperture of two channels in its structure is respectively 4.4x5.6A and 5.1x5.7A, and the BET surface area of the described zeolite is greater than 350m 2 The micropore volume of the zeolite is more than 0.20 ml/g. The silicalite-3 provided by the invention is prepared by roasting precursor silicalite-1 synthesized by hydrothermal reaction of high-purity fumed silica or tetraethoxysilane at a temperature of more than 500 ℃ in a certain atmosphere for a certain time and severely shrinking crystal lattices, has a specific pore channel shape and pore channel openings, and has the advantages of simple and easily realized generation process conditions and no discharge of waste water and waste gas.)

1. A new-structure silica zeolite features that its mole ratio of silica to alumina is greater than 2000, and its structure has a characteristic powder XRD diffraction spectrum, and the open pore diameters of two channels in its structure are 4.4x5.6A and 5.1 x5.7A.

2. The new structure silica zeolite of claim 1, wherein said zeolite has a BET surface area greater than 350m²/g。

3. The new structure silica zeolite of claim 1, wherein said zeolite has a pore volume greater than 0.20 ml/g.

4. The new structure silica zeolite according to claim 1, wherein the zeolite has a characteristic diffraction line d ═ 10.71 ± 0.1a (vs); 9.62 ± 0.1a (vs); 5.75 ± 0.05 a(s); 4.16 ± 0.02a (m); 3.70. + -. 0.01A (vs).

5. The new-structure silica zeolite according to claim 1, wherein the zeolite is produced by subjecting the precursor-silicon zeolite-1 to calcination treatment in a predetermined atmosphere and at a predetermined temperature range for a predetermined period of time, and by causing the crystal lattice to shrink greatly.

6. The new structure silicalite as claimed in claim 5 wherein the precursor silica zeolite-1 is in R-SiO₂-H₂And synthesizing by hydrothermal reaction in an O reactant system.

7. The new structure silicalite as claimed in claim 6 wherein R comprises C1-C4 quaternary ammonium bases, C3-C6 alkyl amines and the silicon source of the reactant system is at least one of high purity fumed silica and ethyl orthosilicate.

8. The new structure silicalite according to claim 7 wherein the reactant system has a molar composition in the range of R/SiO₂＝0.1-0.5，H₂O/SiO₂10-40, the hydrothermal reaction temperature is 110-.

9. The new-structure silicalite as claimed in claim 5, wherein the atmosphere is a mixed gas of air and oxygen with a relative humidity of 10-40%, and the calcination is carried out at 500-800 ℃ for 1-4 hours to greatly shrink the crystal lattice of the precursor silicalite-1.

10. The new-structure silicalite as claimed in claim 9, wherein the hydrothermal synthesis temperature of the reaction mixture is 120-200 ℃ and the reaction time is 5-100 h.

Technical Field

The invention relates to the technical field of silicon dioxide zeolite, in particular to silicon dioxide zeolite with a new structure.

Background

Disclosure of Invention

In view of this, the present invention proposes a new structure of silica zeolite.

The invention provides a new structure silicon dioxide zeolite, the mole ratio of silicon dioxide and aluminium oxide in its chemical composition is greater than 2000, and it has characteristic powder XRD diffraction spectrum, and the aperture of two channel openings in its structure are respectively 4.4x5.6A and 5.1 x5.7A.

Further, the BET surface area of the zeolite is greater than 350m²/g。

Further, the zeolite has a micropore volume greater than 0.20 ml/g.

Further, the characteristic diffraction line of the zeolite is d ═ 10.71 ± 0.1a (vs); 9.62 ± 0.1a (vs); 5.75 ± 0.05 a(s); 4.16 ± 0.02a (m); 3.70. + -. 0.01A (vs).

Further, the zeolite generation process is to carry out roasting treatment on the synthesized precursor silicon zeolite-1 in a certain atmosphere and a certain temperature interval for a certain time, and to generate the precursor silicon zeolite-1 through large-scale lattice contraction.

Further, the precursor silicon zeolite-1 is in R-SiO₂-H₂And synthesizing by hydrothermal reaction in an O reactant system.

Further, the R comprises C1-C4 quaternary ammonium hydroxide and C3-C6 alkylamine, and the silicon source of the reactant system is at least one of high-purity gas-phase white carbon black and tetraethoxysilane.

Further, the molar composition range of the reactant system is R/SiO₂＝0.1-0.5，H₂O/SiO₂10-40, the hydrothermal reaction temperature is 110-.

Further, the atmosphere is air, oxygen, nitrogen, carbon dioxide or mixed gas of air and oxygen with the relative humidity of 10-40%, and the precursor silicalite-1 is greatly shrunk by roasting at the temperature of 500-800 ℃ for 1-4 hours.

Further, the temperature of hydrothermal synthesis of the reaction mixture is 120-200 ℃, and the reaction time is 5-100 h.

Compared with the prior art, the invention has the beneficial effects that the silicalite-3 provided by the invention is generated by roasting precursor silicalite-1 synthesized by hydrothermal reaction of high-purity fumed silica or tetraethoxysilane at a temperature of more than 500 ℃ in a certain atmosphere for a certain time through severe shrinkage of crystal lattices, has a specific shape and an opening of a pore passage, is simple and easy to realize in the generation process condition, and does not discharge any waste water or waste gas.

The proposed silicalite-3 has a BET surface area of more than 350m²G, micropore volumeMore than 0.20ml/g, has good oleophylic and hydrophobic adsorption properties, and can be used for catalyst carriers, adsorption separation of small molecular isomers and removal of organic matters in waste water and waste gas. In the preparation process, a reaction mixture formed by mixing an amorphous silicon raw material and an organic guiding agent is subjected to hydrothermal reaction synthesis under a proper alkaline condition, and then is roasted for a certain time at a temperature of more than 500 ℃ in a certain atmosphere to prepare the hydrophobic Silicalite named as Silicalite-3 (Silicalite-3).

Drawings

FIG. 1 is a schematic structural view of a roasting apparatus with a humidifying pipe according to an embodiment of the present invention;

FIG. 2 is a powder diffraction XRD spectrum of self-made silicalite-1 and silicalite-3 generated therefrom according to an embodiment of the present invention;

FIG. 3 is a graph of the diffraction angle versus calcination temperature for silicalite-1 (051) according to example of the present invention;

FIG. 4 is a powder XRD spectrum of silicalite-1, silicalite-2 and silicalite-3 of examples of the present invention;

FIG. 5 is a schematic representation of the framework structure of silicalite-3 according to an embodiment of the invention;

FIG. 6 is a schematic diagram of the channel opening structure of silicalite-3 according to an embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be further described with reference to specific examples, but the scope of the claims is not limited thereto.

The hydrophobic Silicalite of the new structure of the embodiment of the invention is named as Silicalite-3 (Silicalite-3), has a characteristic powder XRD spectrum, and a characteristic diffraction line d is 10.71 +/-0.1A (vs); 9.62 ± 0.1a (vs); 5.75 ± 0.05 a(s); 4.16 ± 0.02a (m); 3.70. + -. 0.01A (vs).

Specifically, the new structure zeolite has a chemical composition with a silica to alumina molar ratio (SAR) greater than 2000.

Specifically, the new structure zeolite has two kinds of pore channels in its skeleton structure, and the open pore diameters are 4.4X5.6A and 5.1X5.7A, respectively.

In particular, the BET surface area of the new structure zeolite is more than 350m²(iv)/g, micropore volume greater than 0.20 ml/g.

Specifically, the new structure zeolite is produced by sintering the synthesized precursor silicon zeolite-1 (Silicalite-1 with MFI type structure) in a certain atmosphere and a certain temperature interval for a certain time, and greatly shrinking the crystal lattice. In particular, the precursor silicalite-1 is prepared by roasting at 800 ℃ for 1-4 hours in the atmosphere of air, oxygen, nitrogen, carbon dioxide or the mixed gas of air and oxygen with the relative humidity of 10-40% to greatly shrink the crystal lattice of the precursor silicalite-1. The zeolite with the new structure has good oleophylic and hydrophobic adsorption properties, and can be used for catalyst carriers, adsorption separation of small molecular isomers and removal of organic matters in waste water and waste gas.

Wherein the precursor silicon zeolite-1 is in the form of R (organic template) -SiO₂-H₂Synthesized by hydrothermal reaction in an O reactant system; r comprises C1-C4 quaternary ammonium base and C3-C6 alkylamine, the silicon source of the reactant system is high-purity gas-phase white carbon black and tetraethoxysilane, and the molar composition range of the reactant system is R/SiO₂＝0.1-0.5，H₂O/SiO₂10-40, the hydrothermal reaction temperature is 110-180 ℃, and the hydrothermal reaction time is 24-40 hours.

Specifically, the synthesis process of the new-structure silicalite of this example is:

step a, synthesizing precursor silicon zeolite-1 by hydrothermal reaction;

in this process, a 500mL pressure resistant stainless steel autoclave with a capacity of 4F was used for the hydrothermal reaction. High-purity gas-phase white carbon black or ethyl orthosilicate is used as a silicon source, TPAOH (tetrapropylammonium hydroxide), tetrabutylammonium hydroxide (TBA), or n-butylamine and triethylamine are used as template agents R, and the molar ratio of R/SiO is calculated₂＝0.1-0.5，H₂O/SiO₂Pouring 10-40 prepared sol reactant into a stainless steel reaction kettle, sealing, and then placing in an oven to heat to 110-180 ℃, wherein the hydrothermal reaction time is 10-40 hours. After the reaction is finished, cooling the reaction kettle, taking out the reaction product, filtering, washing, drying, roasting to 450-DEG and 500-DEG, removing the template agent R, and obtaining the precursor silicon zeolite-1.

B, roasting the precursor silicalite-1 at a high temperature to obtain silicalite-3 with a new structure, namely, silicalite with a new structure;

referring to fig. 1, a quartz tube or a corundum tube is placed in a hearth of a tubular high-temperature electric furnace, and a quartz boat or a ceramic boat containing precursor silicon zeolite-1 powder is placed in the quartz tube or the corundum tube. The heating temperature of the tubular high-temperature electric furnace is controlled by an electronic temperature controller, and the precision is +/-1 ℃.

The roasting apparatus of the present embodiment includes: the pipe orifice at one side of the quartz pipe or corundum pipe which is provided with the precursor silicon zeolite-1 sample is provided with a pipeline of an external air source which is arranged in a gas steel cylinder 1, the gas comprises air, nitrogen, oxygen or carbon dioxide, when in use, the gas released from a pressure reducing valve 2 of the steel cylinder firstly enters a humidifying device, and the humidifying device is composed of a constant temperature water tank 3 and a humidifying pipe 4 arranged in the constant temperature water tank. When the carrier gas is introduced into the water in the humidifying pipe 4 through the pipeline, the carrier gas is saturated by the water vapor in the humidifying pipe 4. The humidity of the gas flowing out from the humidifying pipe 4 can be controlled to be 10-50% of the relative humidity by a mode of adding ice into the constant-temperature water tank 3 or a mode of raising the temperature of the constant-temperature water tank to a certain degree and keeping the constant temperature. The relationship between the saturated vapor pressure of water and the temperature can be found in a physical and chemical handbook, which is not limited. The humidified gas enters a quartz tube or a corundum tube of a tube type electric furnace 6 to become an atmosphere required to be kept for roasting the precursor silicon zeolite-1, and the precursor silicon zeolite-1 loaded in a quartz boat or a ceramic boat 7 arranged in the quartz tube or the corundum tube is heated to over 500 ℃ in the atmosphere, so that the new structure silicon zeolite-3 is prepared due to the large shrinkage of crystal lattices.

The new-structure silicalite-3 powder prepared in the embodiment of the invention is subjected to XRD identification, and the prepared silicalite-3 powder XRD diffraction spectrum is measured by using an XD-2 powder X-ray diffractometer produced by Beijing Pujingyu general instrument company Limited. The X-ray source is a copper target, 40KV, 30mA and graphite monochromator. The scanning range is 5 degrees to 35 degrees/2 theta, and the speed is 8 degrees (2 theta)/minute. And (3) scanning an XRD powder diffraction spectrum generated by a sample to be detected, and using data processing software carried by the XRD powder diffractometer to print the surface spacing (d) and relative diffraction intensity (I/I0) data of main diffraction peaks of the sample, and comparing the data with the data of characteristic diffraction peaks of the silicalite-3 to identify whether the sample to be detected belongs to the silicalite-3 structure. The characteristic diffraction line for silicalite-3 is d ═ 10.71 ± 0.1a (vs); 9.62 ± 0.1a (vs); 5.75 ± 0.05 a(s); 4.16 ± 0.02a (m); 3.70. + -. 0.01A (vs).

TABLE 2 list of names and structural pore sizes of commonly used silicalites

The combined figure 2 shows the powder diffraction XRD spectrum of the self-made silicalite-1 and the silicalite-3 generated by the self-made silicalite-1 in the embodiment of the invention; the graph clearly shows that the two diffraction peaks have obvious difference in the peak shape and the peak position, the 2 theta angle of the diffraction peak of the silicalite-3 is obviously shifted to a large angle compared with the silicalite-1, and the shift is increasingly prominent for the diffraction peak at a high angle. The 2 theta angle of the diffraction peak of the silicalite-1 was shifted from about 23.1 degrees to about 24.05 degrees of the silicalite-3 at a shift of nearly 1.0 degree as seen from the spectrum of silicalite-1. This indicates that the crystal structures of silicalite-1 and silicalite-3 differ substantially and should not be of the same structural type.

TABLE 3 self-made silicalite-1

Diffraction angle of main diffraction peak in powder XRD diffraction pattern after different temperature roasting

The data in Table 3 show that the positions of the three main characteristic diffraction peaks of the silicalite-1 all have a sudden change towards a large angle when the roasting temperature is above 500 ℃. This phenomenon is indicative of a sudden contraction of the crystal lattice. Thus, the structure of silicalite-3 is clearly different from that of silicalite-1.

FIG. 3 is a graph showing the relationship between the diffraction angle and the calcination temperature of silicalite-1 (051) according to the embodiment of the present invention; the diffraction angle diagram is the diffraction angle diagram of the (051) diffraction peak in a powder XRD diffraction diagram which is shot by calcining self-made silicalite-1 (MFI type) with a silica-alumina molar ratio (SAR being 3000) in a nitrogen atmosphere with certain humidity at different temperatures for 2 hours and cooling. It can be seen that the diffraction angle of the diffraction peak suddenly increases at 500 ℃, indicating that the lattice shrinks significantly, and tends to be gentle above 700 ℃ and begins to stabilize at 780 ℃.

Specifically, the position of the diffraction peak in the XRD powder diffraction principle, i.e., the diffraction angle θ, and the value of the interplanar spacing (d) of the diffraction peak have the following formula relationship:

2d Sinθ＝nλ (1)

where λ is the wavelength of X-rays generated by the anode target material of the radiation source used in the XRD diffractometer, the XRD diffractometer used in this example was a copper target with a characteristic wavelength of 1.5410A (i.e. 0.1541 nm). n is the number of diffraction orders; so n λ is constant for a particular diffraction peak. This formula shows that the diffraction angle θ of a diffraction peak is inversely related to the d value of the diffraction peak.

The lattice symmetry of silicalite-1 is that of an orthorhombic system, the three symmetry axes of the crystal lattice are perpendicular to each other, and the axial lengths (i.e., lattice constants) are a, b, and c, respectively. The value of d for each diffraction peak is related to the lattice constant by the following equation:

1/d²＝h²/a²+k²/b²+l²/c²(2)

wherein h, k and l are diffraction indices of the diffraction peaks, respectively.

According to the formula 1 and the formula 2, the value of the surface distance d can be calculated from the diffraction angle 2 theta value of the series of diffraction peaks obtained by calculation of the actually measured powder XRD diffraction spectrum, and further the lattice constants a, b and c can be calculated from the formula 2.

TABLE 4 lattice constants of silicalite-1 and silicalite-3

Lattice constant/A	Literature data	Boiling of siliconMeasured data of stone-1	Actual measurement data of silicalite-3
				a	20.02	19.78	19.20
b	19.90	19.42	17.28
				c	13.38	13.26	13.39
V (lattice volume/A3)	5332	5095	4442

Collection of Simulated XRD Powder Patterns for Zeolites,FifthRevised Edition,2007,p.279。

Table 3 shows the literature values and the measured values of the lattice parameters of silicalite-1 and the measured values of silicalite-3. Comparing the literature data and the measured data for silicalite-3 and silicalite-1 leads to the following conclusions: in the lattice constant of the silicalite-3, the a value is shortened by 3-4%, the b value is shortened by 11-13%, the c value is basically unchanged, and the lattice volume is reduced by 12-17%.

Referring to FIG. 4, there are shown powder XRD spectra of silicalite-1, silicalite-2, and silicalite-3 of examples of the present invention; in the illustration, the Powder XRD spectra of silicalite-1 and silicalite-2 are "theoretical" Powder diffraction spectra calculated by simulations with specialized software using the coordinates of the Si and oxygen atoms constituting the Zeolites in the crystal lattice obtained by single crystal structure determination, see references:collectionof multiplexed XRD Powder Patterns for Zeolites, Fifth RevisedEdition,2007, p.269, p.279. In the embodiment of the invention, it is obvious from the XRD spectrum of FIG. 4 that the XRD diffraction spectra of silicalite-3, silicalite-1 and silicalite-2 do not belong to the same framework structure type in terms of the number, position and intensity order distribution of peaks.

TABLE 5 characteristic diffraction Peak data for several silicalites

USP 4061724 (1977); i-diffraction intensity; vs-very strong, s-strong, m-moderate

Table 5 shows the literature values of the characteristic diffraction spectrum data of silicalite-1, the measured values of the zeolite synthesized experimentally in this example, and the measured values of the characteristic diffraction spectrum of silicalite-3 produced by the lattice contraction thereof. Obviously, the characteristic XRD diffraction data of the self-made silicalite-1 adopted in the embodiment are consistent with literature values and are obviously different from the silicalite-3 generated by strong lattice contraction, and further prove that the silicalite-3 is different from the silicalite-1 in crystalline phase.

Fig. 5 is a schematic diagram of the framework structure of silicalite-3 according to an embodiment of the present invention, and fig. 6 is a schematic diagram of the pore opening structure of silicalite-3 according to an embodiment of the present invention. The change in lattice constant from Table 4 for this example can be plotted by simple simulations, where the data show that the [100] direction channel opening size for silicalite-3 is 4.4X5.6A and the [010] direction channel opening is 5.1 X5.7A. The [100] direction channel opening size is 5.5X 5.1A and the [010] direction channel opening is 5.6X 5.3A compared to the literature value for silicalite-1. In contrast, silicalite-3 has smaller pore openings than silicalite-1, and apparently becomes "flat" in the [100] direction.

TABLE 6 adsorption statistics of silicalite-1 and silicalite-3

The data in Table 6 show that silicalite-3 has a lower surface area and pore volume and average pore diameter, as measured by low temperature nitrogen adsorption, than silicalite-1, compared to the data for silicalite-1, which is due to lattice shrinkage. The water adsorption of the two is lower than that of normal hexane, which shows that the two have good hydrophobicity. Particular mention should be made of n-hexane adsorption, silicalite-3 being 67mg/g and 56% of 119mg/g of silicalite-1. This is due to the reduction of the opening size of the [100] direction channel to 4.4X5.6A, which prevents n-hexane from adsorbing from the pore.

The process for synthesizing the new-structure silicalite of this example is illustrated by the following examples.