KR100582793B1 - Method of producing for globular silicalite-1 zeolite using silica and acid - Google Patents

Abstract

The present invention relates to a method for synthesizing the particle size to 200 ~ 500nm through the low temperature synthesis method using silica and acid, unlike the production of silicalite-1 zeolite through conventional hydrothermal synthesis, silica light using an acid Preparation of -1 zeolite was easy to synthesize in a short time, and the particle shape was also spherically controlled.

Description

Method of producing spherical silicalite-1 zeolite using silica and acid {Method of producing for globular silicalite-1 zeolite using silica and acid}             

1 is an X-ray diffraction pattern of silicalite-1 powder synthesized using fumed silica and sulfuric acid.

2 is a scanning electron micrograph of silicalite-1 powder synthesized using fumed silica and sulfuric acid.

3 is an X-ray diffraction pattern of powders obtained by varying the synthesis time using fumed silica and sulfuric acid.

4 is a scanning electron micrograph of silicalite-1 powder synthesized using fumed silica and tetrapropylammonium hydroxide.

The present invention relates to the production of nanometer-sized spherical silicalite-1 zeolites, using silica and acid to hydrothermally disperse silicate-1 (silicalite-1) zeolites in a uniform particle size. It relates to a method for producing at a low temperature and a short time through the synthesis method.

     Many zeolites, including A, Y, hydrosodalite, silicalite-1, ZSM-5, and TS-1, can be made in the form of nanoscale particle sizes. Direct application of this type of zeolite can be used as a seed for large crystal growth. However, many interesting applications have been developed recently. For example, nanometer-sized zeolites are coated on a pore support to manufacture microparticle-sized zeolite membranes, to coat carbon fibers with zeolites to remove carbon, and to produce zeolite hollow zeolite fibers, zeolite films, and the like.

    The preparation of zeolites through hydrothermal synthesis, which is being produced for this purpose, is very sensitive to the initial reactants, depending on the silica being chosen. The particle radius of silica, the solubility in impurities and alkaline solutions, affects the overall zeolite synthesis. Zeolite crystal synthesis with the same silica particle radius results in the same distribution of actual nucleation. The uniform mixing of silica according to the chemical composition at the beginning of preparation is determined by the composition of zeolite-structured amine and water, and the aging process of the homogeneous mixture is determined by increasing the reaction temperature through the rearrangement of chemical composition. This also affects the particle shape. This dissociation process of the silica raw material affects the rate of crystalline nucleation during zeolite crystallization. Many other factors, such as synthesis temperature, alkalinity, and molecular sieve inducers other than silica, are also known to affect the crystallization process. Currently, nano-sized zeolite synthesis is attempted at low temperature synthesis of 100-130 ° C. at the existing synthesis temperature of 150-200 ° C., and is attempting to manufacture nano-sized zeolite by changing the composition of the composition.

Examples of nanoparticle-sized zeolites prepared in this way include the use of accelerators for zeolite crystal formation (R. Kumar, P. Mukherjee, RK Pandey, P. Rajmohanan, A. Bhaumik, Microporous and Mesoporous Materials, 1998, 22, 23 . Enhancement of Zeolite Crystal Rate by Addition of Accelerators (R. Kumar, A. Bhaumik, RK Ahei, and S. Ganapathy, Nature, 1996, 381, 298), Synthesis Mechanism of Silicalite-1 Zeolite at Low Temperature (BJ) Schoeman, J. Sterte, and JE Otterstedt, Zeolite, 1994, 14, 568), aging effects in the synthesis of colloidal silicalite-1 zeolite (Q. Li, B. Mihailova, D. Creaser, and J. Sterte, Microporous and and the like Mesoporous Materials, 2001, 43, 51 .).

In addition, in the existing zeolite production technology, the zeolite particle shape is produced in pellet or plate shape. In the form of particles, powder is used as an catalyst or an adsorbent in the industry. Reducing the zeolite concentration through additives tends to reduce the efficiency of the zeolite itself. Therefore, control of shape and size without additives is a major technical problem in using zeolites. Examples of the shape and control technology of the silicalite-1 zeolite include control of the shape of the silicalite-1 zeolite using a large template (L. Tosheva, V. Valtchev, and J. Sterte, Microporous and Mesoporous Materials, 2000, 35-36, 621), the nano-molecular sieves and meta aggregates synthesis (Korea Patent Application No. 1994-7002824 call), and separate colloidal silicalite zeolite synthesis -1 (AE Persson, BJ Schoeman, J. Sterte, and JE Otterstedt , Zeolite, 1994, 14, 557).

However, the conventional nano-sized silicalite-1 manufacturing technology requires a two-step temperature process, first of all using a method of forming a crystal at 100 ℃ through a aging process at 60 ℃, synthesis time also requires more than 60 hours Shall be. In addition, the raw material of silica used in the production of expensive tetraethyl orthosilicate (TEOS, Si (OC ₂ H ₅ ) ₄ ), which shows that the actual cost does not match the cost. The particles of silicalite-1 zeolite produced by this technique are synthesized in nano size, causing aggregation between particles, and the particle shape is also cross-shaped. The presently announced technology has been proposed as a problem in that it takes a long time in the preparation of the particles, and it is not easy to control the particle aggregation and particle shape.

Therefore, the present invention is to provide a method for producing a silicalite-1 zeolite particles having a uniform size at a short synthesis time in a low temperature environment that can solve all the problems of the prior art as described above. .

In order to solve the above problems, the present inventors shorten the synthesis time of the silicalite-1 zeolite by adding a small amount of acid as a starting material of the existing silica, and control the spherical particles at low temperature, and have a uniform size dispersion. The present invention was completed by knowing that the prepared particles can be prepared.

Therefore, in the present invention, in the manufacturing method of the spherical silicalite (silicalite) -1 zeolite, the addition of the organic amine and an acid aqueous solution while stirring with addition of silica to water, while stirring, the acid solution of 0.05 to 0.5 mol per mole of organic amine Provided is a method for producing a spherical silicalite-1 zeolite using silica and acid, which is added after stirring at a ratio and heated.

Hereinafter, the present invention will be described in more detail.

    In order to prepare the spherical silicalite-1 zeolite of the present invention, water is added to a reaction vessel made of Teflon, silica is gradually added while stirring with a magnetic stirrer and stirred for 1 to 4 hours, and then an organic amine is added thereto. The mixture was stirred for 1 to 5 hours, and further stirred for 1 to 12 hours by adding an aqueous sulfuric acid solution. Spherical silicalite-1 zeolite can be manufactured by putting a stirring liquid into oven and heating at a temperature of 80-120 degreeC for a fixed time.

Examples of the silica that may be used in the present invention include liquid or solid sodium silicate, fumed silica, colloidal silica, silica gel, tetraethyl orthosilicate, and the like. The organic amines include tetrapropylammonium hydroxide (TPAOH, (CH ₃ CH ₂ CH ₂ ) ₄ NOH), tetrapropylammonium bromide (TPABr, (CH ₃ CH ₂ CH ₂ ) ₄ NBr) and tetrabutyl ammonium hydroxide There is an id (TBAOH, (CH ₃ (CH ₂ ) ₃ NOH), the use of organic amines have the advantage of controlling the size and shape of the particles.

Acids usable in the present invention include hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), acetic acid (CH ₃ CH ₂ COOH), and the like. The molar concentration of acid is 0.05 to 0.5 per mole of organic amine, and particularly preferably 0.2 to 0.3 mole. The addition of acid accelerates nucleation and crystal growth, making it possible to produce zeolites in a short time. However, when the molar number of acids is 0.05 or less, the crystallization time of the spherical silicalite-1 zeolite is delayed, which is undesirable. If the concentration of is not less than 0.5, it is not preferable because it causes destruction of the skeleton structure to form amorphous silica. In the production process according to the addition of the acid, the mixture is preferably stirred in the acid at 80 to 120 ° C. for a predetermined time for 12 to 24 hours. At less than 80 ° C., agglomeration of particles occurs and at a temperature exceeding 120 ° C. Tends to be too large.

    The finished reactant is washed with distilled water, dried at 60 ° C. in an oven and calcined in air. The firing in air is performed at about 500 to 550 ° C. for about 12 to 15 hours.

    Hereinafter, the present invention will be described in detail with reference to representative examples, but these examples are only intended to illustrate embodiments of the present invention and do not limit the scope of the present invention.

[Examples 1-a to 1-f]

    Water was added to a Teflon container equipped with a magnetic stirrer, followed by stirring for 1 hour by adding fumed silica, followed by stirring for 24 hours by adding tetrapropylammonium hydroxide and an aqueous solution of sulfuric acid (98% by weight), and then putting it in an electric oven. Heated at 100 ° C. for 48 hours. The final molar ratio between reactants is shown in Table 1 below.

delete

The zeolite product obtained after the reaction was washed several times with distilled water and dried in an oven at 60 ℃. In order to remove the amine contained in the zeolite it was calcined for 12 hours in air at 500 ℃.

    The structure and particle shape were confirmed by powder X-ray diffraction analysis and scanning electron microscope. X-ray diffraction patterns are shown in Figure 1, and scanning micrographs are shown in Figure 2. Table 1 shows the size and specific surface area of the silicalite-1 zeolite particles prepared according to various sulfuric acid molar ratios.

division Final moles between reactants Specific surface area (㎡ / g) Particle Size (nm) Tetrapropylammonium hydroxide Silica Sulfuric acid Example 1-a 1.0 3.0 0.05 40 - Example 1-b 1.0 3.0 0.1 380 450 Example 1-c 1.0 3.0 0.2 430 200 Example 1-d 1.0 3.0 0.3 410 300 Example 1-e 1.0 3.0 0.4 60 500 Example 1-f 1.0 3.0 0.5 30 -

Example 2

    Silicalite-1 zeolite was prepared in the same manner as in Example 1, except that sulfuric acid having a mole number of 0.2 was prepared while changing the preparation time from 0 to 48 hours. The resulting X-ray diffraction pattern for the product is shown in Figure 3.

[Examples 3-a and 3-b]

    Silicalite-1 zeolite was prepared in the same manner as in Example 1, except that the added acid was nitric acid or hydrochloric acid. The number of moles was 0.2 mol. The particle size for each zeolite product is shown in Table 2.

Reactant Specific surface area (㎡ / g) Particle size (nm) Example 3-a nitric acid 320 1100 Example 3-b Hydrochloric acid 300 1300

Comparative Example 1

    In order to compare with the spherical silicalite-1 zeolite according to the present invention it was prepared by the conventional general silicalite-1 zeolite manufacturing process.

    12.5 g of tetrapropylammonium hydroxide (98% by weight) was added to a reaction vessel made of Teflon, and 76 g of water was added thereto, followed by stirring for 1 hour. After adding 8 g of fumed silica and stirring for 12 hours, the Teflon reactor was placed in a container made of stainless steel and heated at 150 ° C. for 5 days. Firing process was the same as in Example 1. The particle size for the product is shown in Figure 4.

Comparative Example 2

    Silicalite-1 zeolite was prepared in the same manner as in Example 1, but ammonia water was added at a molar number of 0.2 instead of sulfuric acid. Particle sizes and shapes for the zeolite products are shown in Table 3.

Reactant Specific surface area (㎡ / g) Particle size (nm) ammonia 40 1400

As described above, according to the present invention, the synthesis of silicalite-1 zeolite in a short time is easy, and the particle shape thereof is also advantageous in that it can be easily adjusted to a spherical shape.

Claims (4)

In the manufacturing method of the spherical silicalite-1 zeolite, While adding and stirring the silica with water and adding the organic amine and the acid aqueous solution while stirring, spherical using a silica and an acid, characterized in that the addition and stirring at a ratio of 0.05 ~ 0.5 mol of acid aqueous solution per one mole of the organic amine Method for preparing silicalite-1 zeolite. The method of claim 1, wherein the acid is one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and acetic acid. The method for producing spherical silicalite-1 zeolite using silica and acid according to claim 1, wherein the heating temperature is 80 to 120 ° C and the production time is 12 to 48 hours. The method of claim 1, wherein the spherical crystal of silicalite has a particle size in the range of 200 to 500 nm.

Images