CN101423225A

CN101423225A - Method for preparing silica zeolite Silicalite-2

Info

Publication number: CN101423225A
Application number: CNA2008102274890A
Authority: CN
Inventors: 张锁江; 姜南; 王蕾; 张香平
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2008-11-27
Filing date: 2008-11-27
Publication date: 2009-05-06

Abstract

The invention discloses a rapid synthesis method of a MEL-type full-silicon molecular sieve Silicalite-2 and aims at providing a simple synthesis method of the Silicalite-2 molecular sieve with no miscellaneous crystals, short synthesis cycle, high yield and high crystallinity. The method comprises the following steps of: heating and stirring an organic template agent, a silicon source and deionized water for 0.5-10 hours, then supplementing water, carrying out the confined hydrothermal crystallization for 12-90 hours at the temperature of 100-200 DEG C, cooling down to the room temperature, washing, carrying out centrifugal separation, drying and calcinating to obtain the full-silicon molecular sieve Silicalite-2.

Description

A kind of preparation method of silica zeolite Silicalite-2

Technical field:

The present invention relates to a kind of high-crystallinity does not have the fast preparation method of the silica zeolite Silicalite-2 of stray crystal.

Background technology:

The Silicalite-2 zeolite is the molecular sieve with MEL type skeleton structure, is the total silicon form of ZSM-11, can be used as the inert support of shape selectivity catalyzer and the separation membrane material of organism-water etc., is subjected to extensive concern.

1973 Chu P (USP 3,709,979) use Bu ₄N ⁺Do template and successfully synthesize the ZSM-11 molecular sieve, the Flanigen E M of U.C.C. company in 1978 etc. successfully synthesizes last member's total silicon ZSM-11-Silicalite-2 of Pentasil family again, and then has promoted the fast development in Silicon-rich zeolite synthesis field.Nineteen ninety McWilliam people such as (USP 4,894,212) uses octylame to do template, and the way that adopt to add crystal seed obtains purer ZSM-11 relatively 100～350 ℃ of crystallization 12 hours～10 days.Valyocsik (USP4,941,963) uses diquaternary amine salt (butyl pyrrolidine) to synthesize ZSM-11 as template, and crystallization temperature is 60～250 ℃, and crystallization time is 1～30 day.1993 Beck et al (USP 5,213,786) set forth with Trimethylamine positively charged ion (C _nN ⁺(CH ₃) ₃, n is 9,10,11 or 12) and as organic formwork agent, reasonable crystallization temperature scope is 80～200 ℃, crystallization time is 1～30 day.United States Patent (USP) (USP 6,444,191) is with 3,5-dimethyl-N, and the N-parvoline is done template, and crystallization temperature is 140～200 ℃, and crystallization time is 2～20 days, has synthesized pure ZSM-11 molecular sieve.Aforesaid method technological process relative complex, generally the time intercrystalline degree relatively short is not high, and stray crystal is arranged.Need the long ZSM-11 molecular sieve that just can prepare no stray crystal, high-crystallinity, high conversion of crystallization time, energy consumption is higher, production efficiency is lower.

Summary of the invention

Technical problem to be solved by this invention is to exist crystallization time long in the conventional art, is easy to generate stray crystal, and degree of crystallinity is not high, and the preparation process complicated problems provides the preparation method of a kind of new pure silicon molecular sieve Silicalite-2.This method has that synthesis cycle is short, purity is high, no stray crystal, characteristics such as transformation efficiency height.

For addressing the above problem, the technical solution used in the present invention is as follows: the preparation method of a kind of pure silicon molecular sieve Silicalite-2, with tetraethoxy (TEOS) is the silicon source, positive TBAH (TBAOH) is a template, a certain amount of deionized water is a solvent, by adjusting reactant ratio, the temperature and time of control heated and stirred reaction system, replenish suitable water then, crystallization control temperature etc., make reactant in mixed system, have high reactivity, high reaction rate, and then the shortening synthesis cycle, obtain high-crystallinity and high yield Silicalite-2 molecular sieve.

The silicon source that Silicalite-2 molecular sieve rapid synthesis method provided by the present invention is adopted is tetraethoxy (TEOS), and template is positive TBAH (TBAOH).Synthesis step is as follows:

(1) tetraethoxy, positive TBAH and water are pressed SiO ₂: 0.05～0.5TBAOH:10～50H ₂O mole proportioning mixes in reactor;

(2) mixed reaction solution is at 60～100 ℃ of heated and stirred 0.5～10h;

(3) reaction solution after concentrating makes SiO by adding moisture ₂Mass concentration reach 5%～35%;

(4) reaction system after 12～70 hours, is cooled to room temperature 100～200 ℃ of airtight crystallization of hydro-thermal, obtains crystallized product;

(5) crystallized product wash, centrifugation, drying, roasting, obtain the Silicalite-2 molecular sieve.

The present invention has following technique effect:

Preparation process is simple, and crystallization time is short, and synthetic Silicalite-2 molecular sieve does not have stray crystal, degree of crystallinity height.

Description of drawings

Fig. 1 is the XRD spectra of pure silicon molecular sieve Silicalite-2; Wherein transverse axis is 2 θ angle of diffraction, and the longitudinal axis is a diffracted intensity, and characteristic peak diffracted intensity height promptly shows the degree of crystallinity height, does not occur the characteristic diffraction peak of other crystalline phase simultaneously.

Embodiment

The present invention illustrates with following embodiment, but the present invention is not limited to following embodiment, under the described scope, changes and implements to be included in the technical scope of the present invention before and after not breaking away from.

Embodiment 1

The TBAH aqueous solution of 9.56g tetraethoxy and 32.44g10% is added in the retort of tetrafluoroethylene, and at 60 ℃ of heated and stirred 4.5h, keeping the skin wet makes SiO in the system ₂Mass concentration is 13%, 180 ℃ of airtight crystallization 20 hours, and the crystallization product that obtains is cooled to room temperature, obtains product through washing, centrifugation, drying, roasting, and XRD spectra as shown in Figure 1.

Embodiment 2

Adopt raw material and the method identical with example 1,140 ℃ of airtight crystallization 45 hours are cooled to room temperature with the crystallization product that obtains, and obtain product through washing, centrifugation, drying, roasting, and XRD spectra as shown in Figure 1.

Embodiment 3

Adopt raw material and the method identical with example 1, at 80 ℃ of heated and stirred 1.5h, keeping the skin wet makes the interior SiO of system ₂Mass concentration is 18%, 180 ℃ of airtight crystallization 20 hours.The crystallization product that obtains is cooled to room temperature, obtains product through washing, centrifugation, drying, roasting, XRD spectra as shown in Figure 1.

Embodiment 4

The TBAH aqueous solution of 7.50g tetraethoxy and 22.71g10% is added in the retort of tetrafluoroethylene, and at 80 ℃ of heated and stirred 2.5h, keeping the skin wet makes SiO in the system ₂Mass concentration is 24%, 180 ℃ of airtight crystallization 20 hours.The crystallization product that obtains is cooled to room temperature, obtains product through washing, centrifugation, drying, roasting, XRD spectra as shown in Figure 1.

Embodiment 5

Adopt raw material and the method identical with example 4,140 ℃ of airtight crystallization 36 hours are cooled to room temperature with the crystallization product that obtains, and obtain product through washing, centrifugation, drying, roasting, and XRD spectra as shown in Figure 1.

Claims

1. the preparation method of a silica zeolite Silicalite-2, concrete grammar is as follows:

A) water, silicon source and organic formwork agent are added in the reactor, fully stirred solution is to even;

B) heating and stirring reaction system are added moisture behind the certain hour;

C) the airtight crystallization of hydro-thermal is cooled to room temperature then, obtains crystallized product;

D) product that obtains is washed, centrifugation, drying, roasting, obtain the Silicalite-2 molecular sieve.

2. according to the described preparation method of claim 1, it is characterized in that described organic formwork agent is the tetrabutylammonium hydroxide amine aqueous solution, the silicon source is a tetraethoxy, and the mole proportioning of described reactant is SiO ₂: 0.05～0.5TBAOH:10～50H ₂O.

3. according to the described preparation method of claim 1, it is characterized in that Heating temperature is 60～100 ℃, heat-up time 0.5～10h.

4. according to the described preparation method of claim 1, it is characterized in that, add moisture and make SiO ₂Mass concentration 5%～35%.

5. according to the described preparation method of claim 1, it is characterized in that 100～200 ℃ of crystallization 12～70 hours.