Method for synthesizing MWW mole cular sieve

A synthesis method and molecular sieve technology, which are applied in molecular sieve compounds, molecular sieves and alkali exchange compounds, chemical instruments and methods, etc., can solve problems such as difficulty in controlling the composition of raw materials, increasing the synthesis cost of molecular sieves, and large differences in composition.

Inactive Publication Date: 2007-08-29
EAST CHINA UNIV OF SCI & TECH
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AI Technical Summary

Problems solved by technology

[0008] At present, the aluminum sources used in the synthesis of MWW molecular sieves all use sodium aluminate, which is easy to introduce impurities in sodium aluminate into the synthesized molecular sieves. At the same time, the composition of sodium aluminate from different manufacturers or different batches varies greatly. It is difficult to control the composition of raw materials; the alkalinity adjustment of the synthesis system all uses sodium hydroxide, and the synthesized molecular sieves are all sodium-type molecular sieves. If molecular sieves containing other ions are to be obtained, they must be exchanged, which greatly increases the synthesis cost of molecular sieves. In addition, the synthesis of MWW molecular sieves all adopts hexamethyleneimine (HMI) or adds adamantane quaternary ammonium base therein as template, and these templates are expensive, resulting in higher production costs of MWW molecular sieves

Method used

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  • Method for synthesizing MWW mole cular sieve
  • Method for synthesizing MWW mole cular sieve
  • Method for synthesizing MWW mole cular sieve

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0038] After adding 0.435g of alumina to 72.7g of water under stirring, 3.1g of HMI was added, the pH value was adjusted to about 12 with NaOH, and silica gel (99%) was added to form a reaction mixture. The composition of each component was as follows:

[0039] SiO 2 / Al 2 o 3 =20,H 2 O / SiO 2 =45, R / SiO 2 =0.35, reaction mixture pH=12

[0040] Here R stands for HMI. Put the reaction mixture in a reaction kettle, keep the temperature at 110°C for 8 hours, then raise the temperature to 150°C for 10 days; the reactant is filtered and washed, and dried at 120°C. The obtained sample is marked as MCM-22(P ); MCM-22(P) was calcined at 550°C, and the obtained sample was designated as MCM-22(C). The X-ray diffraction patterns (XRD) of MCM-22(P) and MCM-22(C) are shown in FIG. 1 .

Embodiment 2

[0042] According to the steps of Example 1, adjust the pH value of the system with barium hydroxide, prepare the mixture composed in Table 1, keep the temperature at 119°C for 5 days, and keep the temperature at 155°C for 8 days. After filtering and washing the reactant, dry it at 120°C Dry, baked at 550 ° C, the XRD pattern of each sample is shown in Figure 2.

[0043] The mixture composition of table 1 embodiment 2

[0044] No.

Embodiment 3

[0046] According to the method of embodiment 1, prepared SiO 2 / Al 2 o 3 =25, 30, 35, 40, 45, 50, 85, 100, 150 MCM-22 molecular sieves, the XRD pattern of the product obtained is shown in Figure 3. The results showed that the synthesized samples were all MCM-22 molecular sieves.

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Abstract

The invention supplies a method to compound MWW molecular sieve. It adopts two-stage hydrothermal crystallization method that the room temperature at -119.9 degree centigrade is the first stage and 120-180 degree centigrade is the second stage. The alkali resource is one or two or three of hydroxide of Na, K and Ba. The silicon resource could be solid silica gel or liquid silica gel. And template agent could be HMI or the mixture of HMI and organic amine, quaternary ammonium salt, alcohols, and polyether. The invention has the advantages of compound method and condition is easy to control and low cost. The acid of the product could be altered by changing alkali resources.

Description

technical field [0001] The invention relates to a method for synthesizing molecular sieves, in particular to a method for synthesizing molecular sieves with MWW structure. Background technique [0002] Zeolite molecular sieve is an inorganic microporous material composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron as the basic structural unit. It has been widely used in the fields of catalysis, adsorption and ion exchange; as an excellent solid acid catalyst, it has been successfully It is used in more than 70 acid-catalyzed organic chemical processes. Since the pore size of the molecular sieve catalyst is equivalent to the size of the organic molecules participating in the reaction, it generally has a high selectivity, which is called the shape selectivity of the molecular sieve. When the kinetic radius of the reactant or product is larger than the pore size of the molecular sieve, it cannot pass through the pore size of the molecular sieve. Therefore, w...

Claims

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Application Information

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IPC IPC(8): C01B39/00C01B37/00C01B39/04C01B39/46
Inventor 史建公卢冠忠曹钢郭杨龙
Owner EAST CHINA UNIV OF SCI & TECH
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