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Preparation method of heteroatom MCM-49 zeolite molecular sieve

A technology of MCM-49 and zeolite molecular sieve, applied in the direction of crystalline aluminosilicate zeolite, etc., can solve the problems that affect the preparation cost of MCM-49 molecular sieve, the difficulty of transition metals entering the zeolite framework, and the difficulty of chemical bonds, and achieve high crystallinity. , the effect of reducing the dosage and improving the yield of a single kettle

Inactive Publication Date: 2015-03-25
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, transition metal ions are easily hydrolyzed at high pH to form hydroxides or oxide precipitates, making it more difficult to react with silicon species to form chemical bonds, making it difficult for transition metals to actually enter the zeolite framework, and eventually generate oxides. thing
On the other hand, when adopting hydrothermal crystallization method to synthesize heteroatom MCM-49 zeolite molecule, need to use a large amount of organic template agent, because organic template agent is expensive, has seriously affected the preparation cost of MCM-49 molecular sieve; Meanwhile, after molecular sieve synthesis A large amount of separated mother liquor is alkaline ammonia nitrogen wastewater, and direct discharge will cause serious pollution to the environment

Method used

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  • Preparation method of heteroatom MCM-49 zeolite molecular sieve

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Take 11.31g of tetraethyl orthosilicate and 0.43g of ferric nitrate, add 10.25ml of 0.3M hydrochloric acid aqueous solution to it, adjust the hydrolysis pH value of the solution to 2.0, stir and hydrolyze at 90°C for 2 hours, and make A solution; Sodium hydroxide and 0.415g of sodium aluminate were dissolved in 8.4ml of deionized water to make solution B, and solution B was slowly added dropwise to solution A, fully stirred evenly, so that the molar ratio of the total composition of the mixture was SiO 2 : 0.15Na2 O:0.033Al 2 o 3 :0.02Fe:20H 2 O, the resulting mixture was transferred to an oven at 80° C., and baked for 4 hours until a dry glue was formed. Grinding the dry glue into powder, taking 2g of dry glue and placing it in the upper part of the reaction kettle, and 20g of water and 2g of hexamethyleneimine in the lower part of the reaction kettle. After the reaction kettle was sealed, it was statically crystallized at 158°C for 7 days, and the product was washe...

Embodiment 2

[0032] According to the operating steps and operating conditions of Example 1, the difference is that the aluminum source is aluminum nitrate, the heteroatom compound is chromium nitrate, and the molar ratio of the total composition of the mixture is SiO 2 : 0.3Na 2 O:0.033Al 2 o 3 :0.05Cr:25H 2 O, the drying temperature for preparing dry glue is 50°C, the drying time is 24 hours, the lower part of the reaction kettle is 15g of water and 3g of hexamethyleneimine, the crystallization temperature is 158°C, and the crystallization time is 12 days. The X-ray diffraction and infrared spectrum characterization results of the product prove that the final product is a chromium-doped MCM-49 zeolite molecular sieve. Its X-ray diffraction spectrum (XRD) see figure 1 c, Infrared spectrum (IR) see figure 2 c. Determination of Cr / SiO in Molecular Sieves by Inductively Coupled Plasma (ICP) 2 (molar ratio) = 0.0376.

Embodiment 3

[0034] According to the operating steps and operating conditions of Example 1, the difference is that the silicon source is sodium silicate, the aluminum source is aluminum sulfate, the heteroatom compound is vanadyl sulfate, the acid solution is sulfuric acid, the hydrolysis pH is 4.0, and stirred at 20°C Hydrolyzed for 24 hours, the molar ratio of the total composition of the mixture is SiO 2 : 0.2Na 2 O:0.01Al 2 o 3 :0.01V:35H 2 O, the crystallization temperature is 140°C, and the crystallization time is 15 days. The XRD and IR characterization of the product prove that the final product is a vanadium-doped MCM-49 zeolite molecular sieve. Measurement of V / SiO in Molecular Sieves by Inductively Coupled Plasma (ICP) 2 (molar ratio) = 0.0063.

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Abstract

The invention relates to a synthetic method of an MCM-49 zeolite molecular sieve with heteroatom in a framework. The method is characterized by comprising the following steps: regulating the pH value of a mixed solution of a silicon source and a heteroatom source, and co-hydrolyzing the silicon source and the heteroatom source to obtain a silicon gel precursor A containing heteroatom; uniformly mixing water, an aluminum source and an alkali source in a certain proportion to obtain a solution B; slowly dropwise adding the solution B into the solution A to form a uniform crystallization solution, and heating and evaporating the crystallization solution to dryness to obtain dry gel; putting the dry gel at the upper part of a reaction kettle, putting water and a template agent at the lower part of the reaction kettle, and crystallizing for 3-15 days at 140-180 DEG C after sealing to obtain the MCM-49 zeolite molecular sieve with heteroatom in the framework. The method can be used for avoiding a phenomenon of hydrolyzing the heteroatom to obtain oxide precipitates, and is simple and easy to operate, less in amount of the template agent, capable of recycling the template agent, and less in environmental pollution; and the prepared product is high in crystallization degree and good in repeatability.

Description

technical field [0001] The invention belongs to the field of zeolite molecular sieve synthesis, and relates to a preparation method of MCM-49 zeolite molecular sieve whose frame contains heteroatoms. Background technique [0002] MCM-49 zeolite molecular sieve is a zeolite molecular sieve material (US5236575) with a MWW topology firstly developed by Mobil Corporation of the United States. It has two independent and disconnected pore systems (Science, 1994, 264: 1910- 1912): First, the aperture is The two-dimensional sinusoidal channel of the ten-membered ring; the second is through The diameter of the opening of the ten-membered ring communicating with the outside world is The twelve-membered ring supercage. Due to its unique pore structure, good thermal / hydrothermal stability and suitable acidity, MCM-49 molecular sieves have shown a wide application prospects. [0003] Introducing transition metals (Co, Mn, Cr, V, Ti, Fe, etc.) It has the oxidation-reduction prope...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/04
CPCC01B39/04C01P2002/72
Inventor 张峰吴雅静陈红玉姚成
Owner NANJING UNIV OF TECH