Preparation method of total-silicon molecular sieve Silicalite-1 having high hydrogen bond silicon hydroxyl content

A high-hydrogen-bonding silanol and all-silicon molecular sieve technology, which is applied in molecular sieves and base-exchange compounds, chemical instruments and methods, and inorganic chemistry, can solve problems such as high toxicity, long crystallization time, and expensive templates, and achieve High hydrothermal stability, short crystallization time, and low-cost raw materials

Inactive Publication Date: 2016-10-19
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The templating agent is expensive and highly toxic
Alex K et al. (Nature, 1993,65:239-242) adopted n-propylamine, triethylamine and tetramethylammonium hydroxide as templates, and synthesized Silicalite-1 molecular sieve with white carbon black as silicon source, but it needs Crystallization at 453K for 12 days, longer crystallization time

Method used

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  • Preparation method of total-silicon molecular sieve Silicalite-1 having high hydrogen bond silicon hydroxyl content
  • Preparation method of total-silicon molecular sieve Silicalite-1 having high hydrogen bond silicon hydroxyl content
  • Preparation method of total-silicon molecular sieve Silicalite-1 having high hydrogen bond silicon hydroxyl content

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] Under stirring conditions, the following two solutions were prepared:

[0052] Mixture I: 17.5 g of silica sol (40% SiO 2 , 60%H 2 O, the same below), 1.77g tetrapropylammonium bromide (99%), 16.5g deionized add in the beaker and mix well;

[0053] Mixture II: 2.2mol / L sodium hydroxide homogeneous solution;

[0054] Under constant stirring, the mixture II was slowly added to the mixture I, and stirred for 2 h to obtain a gel with a mass ratio of SiO 2 :N:H 2 O=1:0.06:20, adjust the pH of the gel to 8.5. Among them, with SiO 2 Calculate the number of moles of silicon source, and calculate the number of moles of template agent with N element, the same below. It was transferred to a reaction kettle with a polytetrafluoroethylene lining, sealed and placed in an oven for hydrothermal synthesis, first at 90 °C for 6 hours, and then heated to 165 °C for 14 hours. After the reaction kettle was cooled, the solid was separated from the mother liquor, the solid was washed w...

Embodiment 2

[0058] Under stirring conditions, the following two working solutions were prepared:

[0059] Solution I: add 25g of silica sol, 3.55g of tetrapropylammonium bromide, and 26.5g of deionization into a beaker and mix well;

[0060] Solution II: 2.2mol / L sodium hydroxide homogeneous solution;

[0061] Under constant stirring, solution II was slowly added to solution I and stirred for 4 h. The molar ratio of the initial gel is SiO 2 :N:H 2 O=1:0.08:20, adjust the gel pH to 8.0. The crystallization conditions, washing, drying, roasting and other processes are the same as those in Example 1, and the original powder of molecular sieve Silicalite-1 is prepared. The obtained molecular sieve Silicalite-1 original powder is treated with an ammonium nitrate solution, and the treatment process is shown in Example 1, and finally a hydrogen-type all-silicon molecular sieve is obtained.

[0062] The final product powder was analyzed by X-ray diffraction ( figure 1 (b)), the relative cry...

Embodiment 3

[0064] The raw materials, composition and technological process of the present embodiment are the same as those in Example 2, the difference is that the temperature is kept constant at 70 °C for 10 h, then the temperature is increased at 150 °C and the constant temperature is continued for 20 h, and the final product powder is analyzed by X-ray diffraction ( figure 1 (c)), the relative crystallinity is 101.2%, and its grain size is 200 nm. Its specific surface is 373.8m measured by low temperature nitrogen adsorption and desorption 2 / g, the total pore volume is 0.362cm 3 / g, mesoporous pore volume 0.161cm 3 / g. Infrared detection ( Figure 5 (b)), the relative content of silanols in the molecular sieve is 0.84, 3550cm -1 The peak area at 3740cm -1 The ratio of peak areas at 22:10.7. via NH 3 -TPD detection, the molecular sieve acid content is 0.24mmol / g.

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Abstract

The invention relates to a preparation method of a total-silicon molecular sieve Silicalite-1 having the high hydrogen bond silicon hydroxyl content. The preparation method comprises: (1) mixing a silicon source, a templating agent and water, stirring into a gel, and adjusting the pH value of the gel to 7.5-11.5; and (2) crystallizing the gel of the step (1), washing the crystallized product, separating, and calcining to obtain the total-silicon molecular sieve Silicalite-1, wherein the crystallization comprises the two crystallization processes, the first crystallization process comprises that the crystallization is performed for 1-10 h at a temperature of 60-120 DEG C, and the second crystallization process comprises that the crystallization is performed for 3-24 h after the temperature is increased to 150-200 DEG C. According to the present invention, the total-silicon molecular sieve Silicalite-1 prepared by the preparation method has the high hydrogen bond silicon hydroxyl content, and further maintains high crystallinity, good thermal stability, and good hydrothermal stability of the molecular sieve.

Description

technical field [0001] The invention relates to a preparation method of an all-silicon molecular sieve Silicalite-1, in particular to a preparation method of an all-silicon molecular sieve Silicalite-1 with high hydrogen bond silicon hydroxyl content. Background technique [0002] ZSM-5 zeolite molecular sieve is a high-silicon three-dimensional straight channel structure zeolite developed by Mobil in the 1970s. It has developed pore structure, excellent shape-selective catalytic performance and good hydrothermal stability. etc. are widely used in the petrochemical industry. All-silicon Silicalite-1 molecular sieve has the same pore structure as ZSM-5 molecular sieve, both have ten-membered ring MFI structure, and have two kinds of crossed pores, one is ten-membered ring straight pores with a pore size of 0.51×0.55nm, and the other It is a zigzag-shaped ten-membered ring channel with a diameter of 0.53×0.56nm. The skeleton of the all-silicon Silicalite-1 molecular sieve is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/00
Inventor 李春义孟哲孟晓静
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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