CN1207196C - Nano grade titanium silicon molecular sieve and its synthesis technology - Google Patents

Abstract

The present invention relates to a nanometer titanium-silicon molecular sieve and a synthesizing technology thereof, particularly to a titanium-silicon molecular sieve and a preparing method thereof. The molar composition of the molecular sieve is Na<1(+/-)X>Ti<1.5(+/-)Y>Si<1(+/-)Z>O5, wherein the value of X is from 0.01 to 0.2, the value of Y is from 0.1 to 0.5, and the value of Z is from 0.1 to 0.2. XRD powder diffraction peak (2theta) data comprises 11.40(+/-)0.2, 27.8(+/-)0.2, 36.2(+/-)0.5 and 46.8(+/-)0.5, and crystal cell parameters are: a=b=8.000(+/-)0.500 A, c=12.000(+/-)0.500 A. Crystal particles are tetragonal in shape and are in the size of 10 to 20 nm. Tetrabutyl titanate or tetraisopropyl titanate, ethyl orthosilicate, sodium hydroxide and water are used as raw materials, and a sol-gel method and a hydrothermal synthesizing method are jointly adopted to prepare the nanometer titanium-silicon molecular sieve. With the advantages of fine crystal particles, high reaction activity, no need of expensive templates, low synthesis cost, high exchange capacity on radioactive elements and heavy metal elements, favorable thermal stability and favorable radiation resistant performance, the molecular sieve can be widely used for removing heavy metal pollutants and radioactive pollutants in environment, purifying nuclides, etc.

Description

A kind of Ti-Si nano molecular sieve and synthesis technique thereof

Technical field

The present invention relates to a kind of HTS and synthesis technique thereof, this molecular sieve is mainly used in to be removed radioactive pollutant and the heavy metal contaminants in the environment or carries out the nucleic purification, belongs to environment protection and applied chemistry technical field.

Background technology

Molecular sieve is owing to have uniform microvoid structure and can select suitable molecule to enter its skeleton inside, therefore separates with fluid molecule at gas, aspects such as ion-exchange and catalyzed reaction have wide industrial to use.Along with the continuous increase of industrial requirement, people are carrying out new design and synthetic for the skeleton structure of molecular sieve and the size shape in duct etc., and the kind of molecular sieve constantly increases, and its structure is abundanter and its performance is also more complete.The research development in recent years of HTS is very fast, at the initial stage eighties, Taramasso (the TaramassoM of Italy Enichem company, PeregoG, NotariB, US4410501,1983) etc. people's reported first synthesize the titaniferous molecular sieve TS-1 of a kind of skeleton (MFI type), because it has excellent catalytic performance in the multiple organism selective oxidation reaction that has rare hydrogen peroxide (30wt%) to participate in, be considered to a milestone of molecular sieve research field.People report in succession and synthesize Ti-β (BEA type), Ti-ZSM-12 (MTW type), Ti-M (MOR type), Ti-MCM-41 (hexagonal system), Ti-MCM-48 (isometric system) and Ti-HMS HTS such as (hexagonal systems) subsequently.

The synthetic method of HTS mainly contains following two kinds at present:

(1) isomorphous substitution method

Isomorphous substitution method is with TiCl ₄For the vapor phase process in titanium source and with (NH ₄) ₂TiF ₆Deng the liquid phase method that is the titanium source, claim gas-solid phase isomorphous replacement process (Thangaraj A, Kumar R, et al.Appl.Catal., 1990,57,1～3) again.This method is raw materials used to be generally high silicon or the total silicon zeolite molecular sieve is made silicon source material, with TiCl ₄Be the titanium source material.Isomorphous substitution is reflected in the silica tube fixed-bed reactor and carries out, and uses N ₂Gas is with TiCl ₄Bring reactor into, under 400～700 ℃, carry out the isomorphous substitution certain hour, can obtain HTS (TS), do not change the skeleton structure of zeolite in the isomorphous substitution process, do the silicon source with ZSM-5, ZSM-11 type supersiliceous zeolite molecular sieve with MFI, MEL structure and carry out isomorphous substitution and can obtain corresponding TS-1 and TS-2.The shortcoming of this synthetic method mainly contains the following aspects: the service temperature height, and power consumption is big; Belong to gas-solid and operate mutually, the difficult control of reaction, complex process; To the equipment requirements height, reliability is little; Sample crystal grain is big; Also be difficult to realize industrialization at present.

(2) hydrothermal synthesis method

Hydrothermal synthesis method claims direct synthesis technique again, is present the most frequently used HTS synthetic method.Generally mix by a certain percentage with template, carry out hydrothermal mutually and synthetic by titanium source and silicon source material.Its process normally stirs above-mentioned mixed sols under 70～90 ℃, behind the hydrolysis certain hour, go in the autoclave, in 90 ℃ of ageings 1～2 day, crystallization 2～10 days under 170 ℃ of autogenous pressures again, after the gained crystal washed, filters, dries,, promptly get the former powder of HTS (Reddy J S at 550 ℃ of following roasting 5～10h, Kumar R.Zeolites, 1992,12,95～100).

Used silicon source material is tetraethoxy (TEOS), butyl silicate (TBOS) in the synthesis material; Titanium source material has positive titanium ethanolate (TEOT), positive butyl (tetra) titanate (TBOT); Template is used TPAOH (TPAOH), TBAH (TBAOH) etc. usually.The difference of template causes the difference (Esposito A, Taramasso M, etal.USP4396783,1983) of crystalline structure.When using TPAOH to make template, the synthetic HTS has the MFI structure of ZSM-5 type, i.e. TS-1 (claiming Ti-ZSM-5 again); When being template with TBAOH, the synthetic HTS has the MEL structure of ZSM-11 zeolite type, i.e. TS-2 (claiming Ti-ZSM-11 again).

The shortcoming of this synthetic method mainly contains following several respects at present:

(1) needs to use in a large number the TPAOH template of expensive price in the building-up process.

(2) the HTS particle diameter is more little, and activity is good more.Therefore it is most important to control the HTS grain size, generally should be less than 0.2 μ m, and still the HTS particle diameter that synthesizes at present is many more than 1 μ m.

(3) loading capacity is low, and thermostability and radiation-resistant property are poor.

Summary of the invention

Purpose of the present invention and task provide a kind of Ti-Si nano molecular sieve and synthesis technique thereof, make it in synthetic, need not to re-use expensive template, the synthetic zeolite crystal is tiny, and radioelement and heavy metal element had very high exchange capacity, thermostability and radiation-resistant property are good.

Ti-Si nano molecular sieve of the present invention is characterized in that this Ti-Si nano molecular sieve demonstrates following physicochemical characteristic:

(1) its mole consists of Na _{1 ± X}Ti _{1.5 ± Y}Si _{1 ± Z}O ₅, wherein the X value is 0.01～0.2, and the Y value is 0.1～0.5, and the Z value is 0.1～0.2;

(2) XRD powdery diffractometry peak (2 θ) data are: 11.40 ± 0.2,27.8 ± 0.2,36.2 ± 0.5,46.8 ± 0.5;

(3) unit cell parameters is a=b=8.000 ± 0.500 , c=12.000 ± 0.500 ;

(4) crystal grain is square, is of a size of 10～20 nanometers

(5) outward appearance: white powder.

Above-mentioned nano silicone titanium molecular sieve synthetic process is as follows: with titanium isopropylate ([(CH ₃) ₂CHO] ₄Ti), 5%～15% tetraethoxy ([C ₂H ₅] ₄SiO ₄), 1%～10% sodium hydroxide, 65%～80% water is synthetic raw material (above all be weight percentage, starting material are analytical pure), adopts sol-gel method and hydrothermal synthesis method to finish jointly, its synthetic in turn including the following steps:

(1) by weight percentage the sodium hydroxide of 65%～80% water and 1%～10% is mixed with the aqueous solution of sodium hydroxide;

(2) under continue stirring, be that 5%～15% titanium isopropylate is added drop-wise in the aqueous solution of sodium hydroxide with weight percent, the pH value of solution is controlled at 10～12;

(3) be that 5%～15% tetraethoxy is added drop-wise in the above-mentioned mixed solution with 0.01 milliliters/second～0.1 milliliters/second speed with weight percent, obtain white colloid;

(4) white colloid is transferred in the easy reaction autoclave, carried out hydro-thermal reaction 3～10 days, obtain solid product at 140～250 ℃;

(5) above-mentioned solid product is used acetone and deionized water wash respectively, obtain the white powder sample in drying in oven after the centrifugation.

The present invention synthesizes a kind of Ti-Si nano molecular sieve by using the better starting material of hydrolysis property, adjustment raw material ratio and interpolation order and methods such as pH value of solution value, control rate of addition and hydro-thermal synthesis temperature.This zeolite crystal is tiny, between 10～20nm, has greatly improved the reactive behavior of product; In synthetic, need not to re-use expensive template in addition, significantly reduced synthetic cost; This kind HTS has very high exchange capacity to heavy metal element and radioelement, and thermostability and radiation-resistant property are good, can be widely used in removing heavy metal contaminants and radioactive pollutant and nucleic purification etc. in the environment.

Description of drawings

Fig. 1 is SEM figure of the present invention.Sample particle is very thin as can be seen among the figure, and powder is of a size of nano level.Because nanocrystal has bigger specific surface area and surface free energy, therefore be aggregating state basically, so can not from the SEM photo, find out the concrete pattern of particulate.

Fig. 2 is TEM figure of the present invention.As can be seen from the figure visible particle is the cubic crystal grain of rule, and particle grain size is about 10～20nm.

Embodiment

Embodiment 1:

6% sodium hydroxide joined in 76% the water, under continuing to stir, earlier 8% titanium isopropylate is added drop-wise in the aqueous solution of sodium hydroxide, again 10% tetraethoxy is added drop-wise in the mixed solution with 0.06ml/s speed, obtain white colloid.Then colloid is transferred in the simple and easy autoclave, under 190 ℃ temperature condition, carried out hydro-thermal reaction 4 days.The solid product that obtains is used acetone and deionized water wash respectively, obtains required sample in drying in oven after the centrifugation.

Adopt atomic absorption spectrum (AAS) to measure this sample at 0.1M HNO ₃, the 100ppm caesium the aqueous solution in, can be to the partition ratio of caesium up to 36500ml/g; In the aqueous solution of 0.1M NaOH, 100ppm strontium, can be to the partition ratio of strontium up to 9000ml/g; In the aqueous solution of 0.1M NaOH, 100ppm lithium, can reach 800ml/g to the partition ratio of lithium.

Embodiment 2:

2% sodium hydroxide joined in 80% the water, under continuing to stir, earlier 5% titanium isopropylate is added drop-wise in the aqueous solution of sodium hydroxide, again 13% tetraethoxy is added drop-wise in the mixed solution with 0.02ml/s speed, obtain white colloid.Then colloid is transferred in the easy reaction still, under 140 ℃ of temperature condition, carried out hydro-thermal reaction 10 days.The solid product that obtains is used acetone and deionized water wash respectively, obtains required sample in drying in oven after the centrifugation.

Adopt atomic absorption spectrum (AAS) to measure this sample at 0.1M HNO ₃, the 100ppm caesium the aqueous solution in, can be to the partition ratio of caesium up to 10000ml/g.In the aqueous solution of 0.1M NaOH, 100ppm strontium, can be to the partition ratio of strontium up to 15000ml/g.In the aqueous solution of 0.1M NaOH, 100ppm lithium, can reach 600ml/g to the partition ratio of lithium.

Embodiment 3:

10% sodium hydroxide joined in 70% the water, under continuing to stir, earlier 15% titanium isopropylate is added drop-wise in the aqueous solution of sodium hydroxide, again 5% tetraethoxy is added drop-wise in the mixed solution with 0.09ml/s speed, obtain white colloid.Then colloid is transferred in the easy reaction still, under 250 ℃ of temperature condition, carried out hydro-thermal reaction 4 days.The solid product that obtains is used acetone and deionized water wash respectively, obtains required sample in drying in oven after the centrifugation.

Adopt atomic absorption spectrum (AAS) to measure this sample at 0.1M HNO ₃, the 100ppm caesium the aqueous solution in, can be to the partition ratio of caesium up to 11000ml/g.In the aqueous solution of 0.1M NaOH, 100ppm strontium, can be to the partition ratio of strontium up to 8000ml/g.In the aqueous solution of 0.1M NaOH, 100ppm lithium, can reach 1033ml/g to the partition ratio of lithium.

Claims (2)

1. Ti-Si nano molecular sieve is characterized in that this Ti-Si nano molecular sieve demonstrates following physicochemical characteristic:

(1) its mole consists of Na _{1 ± X}Ti _{1.5 ± Y}Si _{1 ± Z}O ₅, wherein the X value is 0.01～0.2, and the Y value is 0.1～0.5, and the Z value is 0.1～0.2;

(2) XRD powdery diffractometry peak (2 θ) data are: 11.40 ± 0.2,27.8 ± 0.2,36.2 ± 0.5,46.8 ± 0.5;

(3) unit cell parameters is a=b=8.000 ± 0.500 , c=12.000 ± 0.500 ;

(4) crystal grain is square, is of a size of 10～20 nanometers;

(5) outward appearance: white powder.

2. synthetic method of Ti-Si nano molecular sieve according to claim 1, its method in turn includes the following steps:

(1) by weight percentage the sodium hydroxide of 65%～80% water and 1%～10% is mixed with the aqueous solution of sodium hydroxide;

(2) under continue stirring, be that 5%～15% titanium isopropylate is added drop-wise in the aqueous solution of sodium hydroxide with weight percent, the pH value of solution is controlled at 10～12;

(3) be that 5%～15% tetraethoxy is added drop-wise in the above-mentioned mixed solution with 0.01 milliliters/second～0.1 milliliters/second speed with weight percent, obtain white colloid;

(4) white colloid is transferred in the easy reaction autoclave, carried out hydro-thermal reaction 3～10 days, obtain solid product at 140～250 ℃;

(5) above-mentioned solid product is used acetone and deionized water wash respectively, obtain the white powder sample in drying in oven after the centrifugation.

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