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Seed crystal synthesis method for preparing ZSM-23 molecular sieve

A technology of ZSM-23 and molecular sieve, which is applied in the field of ZSM-23 molecular sieve preparation by seed crystal synthesis method, can solve the problems of a large amount of harmful gas, high crystallization temperature, and long crystallization time, and achieve low price, lower crystallization temperature, The effect of reducing loss

Inactive Publication Date: 2013-03-27
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the use of organic templates has many disadvantages: it is not conducive to the reduction of cost; energy is wasted in the process of roasting templates, and a large amount of harmful gases are generated; many organic templates themselves have strong toxicity; take a long time

Method used

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  • Seed crystal synthesis method for preparing ZSM-23 molecular sieve
  • Seed crystal synthesis method for preparing ZSM-23 molecular sieve
  • Seed crystal synthesis method for preparing ZSM-23 molecular sieve

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Embodiment 1: Synthesis of ZSM-23 zeolite molecular sieve by seed crystal method

[0019] First, the 8.12gH 2 O and 0.092g of aluminum sulfate are mixed evenly, then 0.38g of NaOH is added to it, and then 3.32g of silica sol with a silica content of 30.5% is added under stirring, and the stirring is continued until the solution becomes uniform, and then 10% ZSM-23 molecular sieve is added to make Seed crystal (the amount of seed crystal is represented by input SiO 2 mass percent calculation). Add the reaction raw materials into a polytetrafluoroethylene stainless steel reaction kettle, perform dynamic crystallization at 160°C for 10 hours to complete the crystallization, filter the product with suction, and dry it to obtain the product. The proportioning of reaction raw material is as follows:

[0020] SiO 2 : 0.008319Al 2 o 3 :0.27 Na 2 O : 35H 2 O. The mass ratio of seed crystal to silicon source is 10%.

[0021] Its structure is ZSM-23 zeolite molecular s...

Embodiment 2

[0022] Embodiment 2: Secondary utilization of product prepared by seed crystal method

[0023] 8.12gH 2 O and 0.056g of aluminum sulfate are mixed evenly, then 0.35g of NaOH is added thereto, and then 3.32g of silica sol with a silicon dioxide content of 30.5% is added under stirring, and the stirring is continued until the solution becomes uniform, and then 10% of the compound synthesized in Example 1 is added. The ZSM-23 molecular sieve is used as the seed crystal (the amount of seed crystal is based on the input SiO 2 Calculated by mass percentage), after stirring evenly, the gel was added into a polytetrafluoroethylene stainless steel reactor, and dynamically crystallized in an oven at 160°C for 10 hours. The product was filtered with suction and dried.

[0024] image 3 The XRD spectrum of the product synthesized by the reuse of the ZSM-23 zeolite molecular sieve prepared by the seed crystal method, it can be seen from the spectrum that the product has a typical ZSM-23...

Embodiment 3

[0026] Embodiment 3: Synthesis of ZSM-23 under relatively mild temperature

[0027] The preparation of the initial silica-alumina gel is the same as in Example 1. The preparation process of ZSM-23 zeolite molecular sieve is as follows: in the gel system prepared in embodiment 1, add 10% ZSM-23 molecular sieve as crystal seed (the amount of seed crystal is represented by input SiO 2 mass percentage), after stirring evenly, the gel was added into a polytetrafluoroethylene stainless steel reactor, and dynamically crystallized in an oven at 140°C for 50h. The product was filtered with suction and dried. The obtained product is analyzed by X-ray diffraction and its composition is ZSM-23 zeolite molecular sieve.

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Abstract

The invention relates to a preparation method of a molecular sieve, and aims to provide a seed crystal synthesis method for preparing a ZSM-23 molecular sieve. The method comprises specific steps as follows: mixing water and an aluminum source; adding NaOH; adding a silicon source with stirring; continuing to stir until the solution to forms silica-alumina gel; adding ZSM-23 molecular sieve seed crystal into silica-alumina gel and stirring; then placing the mixture in a reaction kettle, and crystallizing at 140-180 DEG C for 2-50h; and conducting suction filtration and drying on the product to obtain a ZSM-23 molecular sieve raw powder. The whole production process of the invention does not use an organic template agent, greatly shortens crystallization time and lowers crystallization temperature, thus reducing unnecessary loss in the production process. The inorganic materials used in the production are environment-friendly, and low-cost; and the ZSM-23 zeolite molecular sieve synthesized by the invention maintains good crystallinity and purity, and has favorable catalytic reaction activity.

Description

technical field [0001] The invention relates to a method for preparing molecular sieves, in particular to a method for preparing ZSM-23 molecular sieves by a seed crystal synthesis method. Background technique [0002] Molecular sieves are widely used in catalysis, ion exchange, adsorption and separation due to their open structure and large surface area. Plank et a1 synthesized ZSM-23 molecular sieve (USP4076,842) for the first time using pyrrolidine as a template. ZSM-23 is a medium pore high silica zeolite with MTT topological structure, which contains five-membered rings, six-membered rings, and ten-membered rings, among which the ten-membered rings are one-dimensional non-crosslinked channels. The channel size of the member ring is 0.45nm×0.52nm, which is smaller than that of ZSM-5. Due to its special pore structure and strong surface acidity, it is widely used in the isomerization of butene, xylene isomerization and MTG reaction, especially in the isomerization react...

Claims

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Application Information

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IPC IPC(8): C01B39/04
Inventor 孟祥举吴勤明肖丰收
Owner ZHEJIANG UNIV
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