Method for analyzing contents and valence states of metals inside and outside doped mesoporous molecular sieve framework

A mesoporous molecular sieve and molecular sieve technology, which is applied in the field of analyzing the content and valence of metal elements inside and outside the framework of doped mesoporous molecular sieves, can solve the problems of inaccurate, inaccurate description of content, inability to determine metal valence and position, etc. simple method effect

Inactive Publication Date: 2011-07-20
NANJING TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, it is difficult to comprehensively and accurately analyze the content and valence state of doped metal ions inside and outside the molecular sieve framework by instrumental analysis methods.
For example, ICP can only analyze the content of metals and is not accurate enough, and cannot determine the valence and position of metals
Ultraviolet light can only qualitatively analyze the state of metal elements, but cannot make an accurate description of the content
At present, there is no comprehensive and accurate analysis method report on the content, valence state and position of metal elements in doped mesoporous silica molecular sieves.

Method used

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  • Method for analyzing contents and valence states of metals inside and outside doped mesoporous molecular sieve framework
  • Method for analyzing contents and valence states of metals inside and outside doped mesoporous molecular sieve framework
  • Method for analyzing contents and valence states of metals inside and outside doped mesoporous molecular sieve framework

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Example 1: Analysis of cobalt-containing MCM-41. Take 0.1g of the sample and soak it in 2mL of 18mol / L concentrated sulfuric acid at 100°C for 12h, and dissolve it in 20mL of 0.5mol / L dilute sulfuric acid at 15°C for 10min. The mixture was centrifugally filtered with deionized water, no metal ions were detected in the residue, and the metal ion clear liquid was obtained with a volumetric flask to constant volume. =5-6 in the hexamethylenetetraammonium buffer system, use EDTA to directly titrate divalent cobalt ions, and trivalent cobalt ions can be reduced by KI and then titrated with EDTA.

[0023] The specific results are shown in Table 1, and the data is the mass percentage of cobalt in the material.

[0024] Table 1

[0025]

[0026] a: total cobalt content - surface cobalt content.

Embodiment 2

[0027] Example 2: Analysis of Iron-Containing MCM-41. Take 0.1g of the sample and soak in 4mL of 16mol / L concentrated nitric acid at 100°C for 12h, and dissolve and stir in 20mL of 0.5mol / L dilute nitric acid at 20°C for 10min. The mixture was centrifugally filtered with deionized water, no metal ions could be detected in the residue, and the obtained clear liquid was constant volume, using sulfosalicylic acid as an indicator, and using hydrochloric acid to control the pH=1.5-2, and directly titrated ferric ions with EDTA. Since the synthesized sample uses ferric nitrate as the iron source and is roasted at 550°C, there is no divalent iron ion in the sample. The specific results are shown in Table 2, and the data is the mass percentage of iron in the material.

[0028] Table 2

[0029]

[0030]

[0031] b: total iron content - surface iron content.

example 3

[0032] Example 3: Analysis of vanadium-containing MCM-41. Take 0.1g of the sample and soak it in 5mL of 6mol / L sodium hydroxide at 60°C for 6h, and dissolve it in 40mL of 0.5mol / L sodium hydroxide at 20°C for 10min. The mixture was centrifugally filtered with deionized water, no metal ions could be detected in the residue, the obtained clear liquid was constant volume, and N-phenyl anthranilic acid was used as an indicator, and pentavalent vanadium was directly titrated with ammonium ferrous sulfate under strong acidic conditions. The tetravalent vanadium can be oxidized to pentavalent by potassium permanganate and then analyzed. The specific results are shown in Table 3, and the data is the mass percentage of vanadium in the material.

[0033] table 3

[0034]

[0035] c: total vanadium content - surface vanadium content.

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Abstract

The invention provides a method for analyzing the contents and the valence states of metals inside and outside a doped mesoporous molecular sieve framework. The method comprises the following steps of: soaking a doped mesoporous molecular sieve with concentrated acid or strong base at higher temperature for a certain time, centrifuging and filtering, or repeating the operations until metal ions are not detected in waste dreg, and titrating and analyzing supernatant to obtain total metal content of the doped mesoporous molecular sieve; adding diluted acid or alkali in the doped mesoporous molecular sieve at room temperature and stirring for a certain time, centrifuging and filtering, or repeating the operations until metal ions are not detected in the filtrate, and titrating and analyzing supernatant to obtain the surface metal content of the doped mesoporous molecular sieve; and removing surface metal ions to obtain the content of the metal in the molecular sieve framework. The metal ions with different contents and valence states can be analyzed by a standard titration method. The invention almost covers all the metal analysis of the doped mesoporous molecular sieve.

Description

technical field [0001] The invention relates to a method for analyzing the content and valence state of metal elements inside and outside the framework of doped mesoporous molecular sieves, in particular to a chemical method for dissolving metal ions in mesoporous molecular sieves with acid or alkali and analyzing them by titration. Background technique [0002] In 1992, Mobil scientists successfully synthesized the M41S family of mesoporous silica materials using cationic surfactants for the first time. Due to the regular pore structure and narrow pore size distribution of M41S mesoporous material, the pore diameter can be adjusted, and the specific surface area is large (700m -2 / g or more), regular and ordered pore structure, and good thermal stability make it have broad application prospects in the fields of catalysis, adsorption and separation, and materials. However, due to the lack of active sites in pure silicon mesoporous materials, its application in catalysis and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N31/16
Inventor 孔岩孙鹏杨渊李洁平张生命
Owner NANJING TECH UNIV
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