阅读说明：本技术 一种Ti-ZSM-5分子筛的制备方法 (Preparation method of Ti-ZSM-5 molecular sieve ) 是由 王于 于浩淼 王贤彬 王炳春 李进 于 2020-12-23 设计创作，主要内容包括：本发明提供了一种Ti-ZSM-5分子筛的制备方法,主要包括以下步骤：将碱源、硅源、晶种、钛源置于研钵中混合,研磨均匀后,将混合物转至反应釜中,在100～220℃的条件下晶化0.08～5d；晶化完成后对反应产物进行抽滤、烘干,最终制得Ti-ZSM-5沸石分子筛。本发明所述的Ti-ZSM-5分子筛的制备方法工艺简单、成本低,得到的Ti-ZSM-5分子筛耐热性能好,能够有效净化汽车尾气中的有害气体,具有良好的工业化生产前景和巨大的经济价值。(The invention provides a preparation method of a Ti-ZSM-5 molecular sieve, which mainly comprises the following steps: placing an alkali source, a silicon source, a seed crystal and a titanium source in a mortar for mixing, uniformly grinding, transferring the mixture to a reaction kettle, and crystallizing for 0.08-5 d at the temperature of 100-220 ℃; and after crystallization, carrying out suction filtration and drying on the reaction product to finally prepare the Ti-ZSM-5 zeolite molecular sieve. The preparation method of the Ti-ZSM-5 molecular sieve has the advantages of simple process and low cost, and the obtained Ti-ZSM-5 molecular sieve has good heat resistance, can effectively purify harmful gases in automobile exhaust, and has good industrial production prospect and great economic value.)

1. A preparation method of a Ti-ZSM-5 molecular sieve is characterized by comprising the following steps:

1) placing an alkali source, a silicon source, a seed crystal and a titanium source in a mortar for mixing, and uniformly grinding;

2) transferring the mixture obtained in the step 1) to a reaction kettle for crystallization;

3) and after crystallization, carrying out suction filtration and drying on the reaction product to finally prepare the Ti-ZSM-5 zeolite molecular sieve.

2. The method of claim 1, wherein the titanium source in step 1) is tetrabutyl titanate.

3. The method for preparing the Ti-ZSM-5 molecular sieve of claim 1, wherein the alkali source in step 1) is one or both of potassium hydroxide and sodium hydroxide.

4. The method for preparing the Ti-ZSM-5 molecular sieve of claim 1, wherein the silicon source in step 1) is one or both of solid silica gel and white carbon black.

5. The method of claim 1, wherein the seeds in step 1) are all-silica ZSM-5 zeolite seeds.

6. The method for preparing the Ti-ZSM-5 molecular sieve according to claim 1, wherein the molar ratio of the raw materials added in the step 1) is 1: 0.02-0.15: 25-125.

7. The preparation method of the Ti-ZSM-5 molecular sieve of claim 1, wherein the seed crystal is added in step 1) in an amount of 1-10% by mass of the silicon source.

8. The method for preparing the Ti-ZSM-5 molecular sieve of claim 1, wherein the crystallization temperature in step 2) is 100-220 ℃ and the crystallization time is 0.08-5 d.

Technical Field

The invention relates to the field of chemical synthesis technology and application thereof, in particular to a preparation method of a Ti-ZSM-5 molecular sieve.

Background

ZSM-5 zeolite is a widely studied high-silicon zeoliteHas two mutually crossed channel systems, the ten-membered ring channel parallel to the a-axis direction is Z-shaped, and the pore diameter isThe ten-membered ring channel parallel to the b-axis direction is linear, and the aperture isZSM-5 is a high-silicon molecular sieve rich in five-membered rings, and double five-membered rings (D5R) are generally considered as precursors for forming ZSM-5, and are connected through a shared edge to form a skeleton chain of the ZSM-5 molecular sieve, and the skeleton chain is further connected into a sheet to form a ZSM-5 skeleton structure. First synthesized in 1972 by the company Mobil, Argauer et al. ZSM-5 has a two-dimensional ten-membered ring channel with a space group of Pmna, orthorhombic system. The unit cell parameters are: α is 90.0 °, β is 90.0 °, γ is 90.0 °, Framework Density (FDSi) is an ideal unit cell composition of the ZSM-5 molecular sieve, and may be expressed as Na_n(H₂O)₁₆Al_nSi_96-nO₁₉₂Wherein the atomic number of Al is 0-27. The ZSM-5 zeolite molecular sieve has unique pore channel structure characteristics and higher thermal stability and hydrothermal stability, so that the zeolite molecular sieve is widely applied to the petrochemical fields of hydrocarbon shape-selective cracking, alkylation, isomerization, disproportionation, etherification, dewaxing and the like.

With the popularization of automobiles, the emission of automobile exhaust causes serious pollution to the environment, so that the treatment of harmful gases in the automobile exhaust is very necessary. The catalyst is the key of the purification effect, so the development of the high-efficiency catalyst is one of the best measures for controlling the automobile exhaust emission. With the improvement of catalyst preparation technology, two active centers of oxidation and reduction coexist on the same catalyst, and finally a three-way catalyst TWC (three-way catalyst) is developed. Wherein the catalyst coating comprises gamma-Al₂O₃The rare earth-transition metal composite oxide and the active components of noble metals such as Pt, Rh and Pd can oxidize and reduce three pollutants (carbon monoxide (CO), Hydrocarbon (HC) and oxynitride (NO) in the exhaust gas of the engine_x) Simultaneous conversion into harmless water (H)₂O), carbon dioxide (CO)₂) And nitrogen (N)₂) However, the three-way catalyst has the disadvantages of high cost and low high temperature resistance. Therefore, it is urgently needed to develop a synthetic method of a novel automobile exhaust catalyst which is simple in synthetic method, low in cost and applicable to industrial production so as to solve the problems in the prior art.

Disclosure of Invention

In order to solve the technical problems of high cost and low high temperature resistance of the automobile exhaust purification catalyst in the prior art, the invention provides a preparation method of a Ti-ZSM-5 molecular sieve, which comprises the following steps:

1) placing an alkali source, a silicon source, a seed crystal and a titanium source in a mortar for mixing, and uniformly grinding;

2) transferring the mixture obtained in the step 1) to a reaction kettle for crystallization;

3) and after crystallization, carrying out suction filtration and drying on the reaction product to finally prepare the Ti-ZSM-5 zeolite molecular sieve.

Further, in the above technical solution, the titanium source in step 1) is tetrabutyl titanate.

Further, in the above technical solution, the alkali source in step 1) is any one of potassium hydroxide and sodium hydroxide.

Further, in the above technical solution, the silicon source in step 1) is any one of solid silica gel or white carbon black.

Further, in the above technical solution, the seed crystal in step 1) is an all-silicon ZSM-5 zeolite seed crystal.

Further, in the above technical solution, the molar ratio of the added raw materials in step 1) is 1: 0.02-0.15: 25-125.

Further, in the above technical solution, the seed crystal addition amount in the step 1) is SiO₂1 to 10% by mass.

Further, in the technical scheme, the crystallization temperature in the step 2) is 100-220 ℃, and the crystallization time is 0.08-5 d.

Compared with the prior art, the invention has the beneficial technical effects that:

(1) the method for preparing the Ti-ZSM-5 zeolite molecular sieve avoids the use of expensive organic template in the prior art, simplifies the synthesis process and greatly reduces the synthesis cost of the molecular sieve;

(2) the molecular sieve prepared by the invention is a high-temperature resistant catalyst, has good stability at high temperature, can effectively treat harmful gas in automobile exhaust, and plays a positive role in environmental management;

(3) the synthetic raw materials adopted by the invention are low in price and easy to obtain, have a large-scale industrial production prospect, and have important significance in the field of actual chemical production.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is an XRD pattern of a Ti-ZSM-5 molecular sieve obtained in example 1 of the present invention;

FIG. 2 is an SEM image of the Ti-ZSM-5 molecular sieve obtained in example 1 of the present invention;

FIG. 3 is a graph showing the catalytic effect of the Ti-ZSM-5 molecular sieve obtained in example 1 of the present invention.

Detailed Description

The invention provides a preparation method of a Ti-ZSM-5 molecular sieve, which comprises the following steps:

1) placing an alkali source, a silicon source, a seed crystal and a titanium source in a mortar for mixing, and uniformly grinding;

2) transferring the mixture obtained in the step 1) to a reaction kettle for crystallization;

3) and after crystallization, carrying out suction filtration and drying on the reaction product to finally prepare the Ti-ZSM-5 zeolite molecular sieve.

In one embodiment, in the above technical solution, the titanium source in step 1) is tetrabutyl titanate.

In one embodiment, in the above technical solution, the alkali source in step 1) is any one of potassium hydroxide or sodium hydroxide.

In an embodiment, in the above technical scheme, the silicon source in step 1) is any one of solid silica gel and white carbon black.

In one embodiment, in the above technical scheme, the seed crystal in the step 1) is an all-silicon ZSM-5 zeolite seed crystal.

In one embodiment, in the above technical solution, the molar ratio of the added raw materials in step 1) is 1: 0.02-0.15: 25-125.

In one embodiment, in the above technical solution, the seed crystal addition amount in the step 1) is SiO₂110% of the mass.

In one embodiment, in the above technical solution, the crystallization temperature in step 2) is 100 to 220 ℃, and the crystallization time is 0.08 to 5 days.

The preparation method of the Ti-ZSM-5 molecular sieve of the present invention is further illustrated with reference to the following examples.

Example 1

A preparation method of a Ti-ZSM-5 molecular sieve automobile exhaust catalyst comprises the following steps:

firstly, placing 16.70g of white carbon black, 1.54g of NaOH and 0.33g of all-silicon ZSM-5 zeolite seed crystal (2%) in a mortar for grinding for 2min, then dripping 3.75g of tetrabutyl titanate into the mixture, and uniformly grinding to obtain a reaction raw material; and finally, adding the reaction raw materials into a polytetrafluoroethylene stainless steel reaction kettle, crystallizing at 180 ℃ for 2 days to obtain complete crystallization, and performing suction filtration and drying on the product to obtain a product No. 1. The molar ratio of the reaction raw materials is as follows: SiO 2₂:Na₂O:TiO₂＝1:0.07:0.04。

The XRD spectrum of this example is shown in fig. 1, and it can be seen from the scanning electron micrograph that the synthesized product is in the form of a block, which is typical of the ZSM-5 zeolite molecular sieve.

Example 2

A preparation method of a Ti-ZSM-5 molecular sieve automobile exhaust catalyst comprises the following steps:

placing 17.27g of white carbon black, 1.59g of NaOH and 0.34g of all-silicon ZSM-5 zeolite seed crystal (2%) in a mortar for grinding for 2min, then dropwise adding 0.97g of tetrabutyl titanate into the mixture, and uniformly grinding to obtain a reaction raw material;and finally, adding the reaction raw materials into a polytetrafluoroethylene stainless steel reaction kettle, crystallizing at 180 ℃ for 2 days to obtain complete crystallization, and performing suction filtration and drying on the product to obtain a product No. 2. The molar ratio of the reaction raw materials is as follows: SiO 2₂:Na₂O:TiO₂＝1:0.07:0.01。

XRD and SEM analysis of the 2# Ti-ZSM-5 zeolite molecular sieve shows that the X-ray diffraction pattern is the same as that in attached figure 1 and the scanning electron microscope is similar to that in attached figure 2.

The Ti-ZSM-5 molecular sieve automobile prepared in the example 1 is used as an automobile exhaust catalyst, the conversion rates of CO and NO in automobile exhaust are examined, and the test is carried out in a fixed bed reactor. The measurement method is as follows:

adding the Ti-ZSM-5 molecular sieve automobile exhaust catalyst into a fixed bed reactor, introducing CO and NO into the fixed bed reactor by using argon as carrier gas, heating the fixed bed reactor at the heating rate of 2 ℃/min, and finally heating to 620 ℃. The conversion rates of CO and NO are tested, and the curve of the change relationship of the conversion rates of CO and NO with the temperature is shown in figure 3. It can be seen from fig. 3 that the catalytic reaction starts to occur at 300 c and the highest catalytic efficiency is reached at 620 c. Finally, the conversion rate of NO in the automobile exhaust reaches 92 percent, the conversion rate of CO reaches 84 percent,

therefore, the catalyst prepared by the method can perform CO catalysis and NO reduction reactions at higher temperature. The temperature is more consistent with the actual environment temperature for treating the automobile exhaust. The product related to the invention has potential practical application value.

The above embodiments are only for further illustration of the present invention and are not intended to limit the present invention, and all equivalent implementations of the present invention should be included in the scope of the claims of the present invention. The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.