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 are applied in the field of analyzing the content and valence of metal elements inside and outside the doped mesoporous molecular sieve framework, which can solve the problem of inaccuracy and analyze the content and valence of doped metal ions inside and outside the molecular sieve framework. description and other problems, to achieve the effect of a simple method

Inactive Publication Date: 2010-09-15
NANJING UNIV OF TECH
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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 ...

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 MCM-41 containing cobalt. Take 0.1g of the sample and soak in 2mL of 18mol / L concentrated sulfuric acid at 100°C for 12h, and dissolve and stir 20mL of 0.5mol / L dilute sulfuric acid at 15°C for 10min. The mixture is filtered with deionized water by centrifugation. No metal ions can be detected in the residue. The metal ion clear liquid is obtained and the volume is fixed with a volumetric flask. The obtained clear liquid is fixed to volume with malachite green as a contrast agent and xylenol orange as an indicator. = 5-6 hexamethylenetetraammonium buffer system uses EDTA to directly titrate the divalent cobalt ion, and the trivalent cobalt ion can be reduced by KI and then titrated with EDTA.

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

[0024] Table 1

[0025]

[0026] a: Total cobalt amount-surface cobalt amount.

Embodiment 2

[0027] Example 2: Analysis of iron-containing MCM-41. Take 0.1g of the sample and soak 4mL of 16mol / L concentrated nitric acid at 100℃ for 12h, and dissolve and stir 20mL of 0.5mol / L dilute nitric acid at 20℃ for 10min. The mixture was filtered with deionized water by centrifugation, and no metal ions were detected in the residue. The resulting clear liquid was constant volume, using sulfosalicylic acid as an indicator, and hydrochloric acid to control the pH=1.5-2 when the ferric ion was directly titrated with EDTA. Since the synthesized sample uses ferric nitrate as the iron source and is calcined at 550°C, there is no ferrous ion in the sample. The specific results are shown in Table 2. 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 with 5mL of 6mol / L sodium hydroxide at 60℃ for 6h, and dissolve 40mL of 0.5mol / L sodium hydroxide at 20℃ for 10min. The mixture was filtered with deionized water by centrifugation. No metal ions could be detected in the residue. The resulting clear liquid was fixed to volume. Using N-phenyl-anthranilic acid as an indicator, the pentavalent vanadium was directly titrated with ferrous ammonium sulfate under strong acid conditions. The tetravalent vanadium can be oxidized to pentavalent by potassium permanganate and analyzed. The specific results are shown in Table 3. 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 sieve, in particular to a chemical method that uses acid or alkali to dissolve metal ions in mesoporous molecular sieve and adopts titration for analysis. Background technique [0002] In 1992, scientists from Mobil Company 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 the M41S mesoporous material, the pore diameter is adjustable, and the specific surface area is large (700m -2 / g above), regular and ordered pore structure, and good thermal stability, making 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 c...

Claims

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Application Information

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IPC IPC(8): G01N31/16
Inventor 孔岩孙鹏杨渊李洁平张生命
Owner NANJING UNIV OF TECH
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