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Method for preparing niobium-silicon molecular sieve

A silicon molecular sieve and silicon source technology, applied in molecular sieve compounds, molecular sieve catalysts, chemical instruments and methods, etc., can solve the problems of high price, limited source of raw materials, and high production costs, and achieve low prices, reduce production costs, and avoid impact. Effect

Inactive Publication Date: 2004-12-29
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to overcome the shortage of raw material sources for preparing niobium-containing molecular sieves in the previous literature, and tetrapropylammonium hydroxide is used as a template agent, which is expensive and thus causes high production costs. The present invention provides a new A method for preparing niobium-silicon molecular sieves. The raw materials used in this method are cheap and easy to obtain, and the amount of template agent is low. Hydrogen-type molecular sieves can be directly obtained without ammonium exchange post-treatment process, which reduces environmental pollution, making the prepared niobium-silicon molecular sieves less costly and The preparation steps are relatively simple

Method used

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  • Method for preparing niobium-silicon molecular sieve
  • Method for preparing niobium-silicon molecular sieve

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Add 2 grams of oxalic acid in 90 milliliters of deionized water, after dissolving, add 0.65 grams of hydrated niobium oxide, 6 grams of template agent tetrapropylammonium bromide (TPABr), 5 grams of ammonium fluoride and 30% of silica sol (SiO 2 Weight) 27 grams, stirred evenly, the pH of this reaction mixture=6.5, stirred and homogenized for 10 minutes, then transferred to a stainless steel crystallization reactor with polytetrafluoroethylene lining, crystallized at 150 ° C under autogenous pressure for 120 After 1 hour, the obtained crystallized product was filtered, washed and dried to obtain 8.5 grams of molecular sieve powder, and then calcined at 550° C. for 3 hours to obtain niobium-silicon molecular sieve. The molar composition of the reaction mixture is: SiO 2 / Nb 2 o 5 =18, TPABr / SiO 2 =0.17, F - / SiO 2 = 1.0, H 2 O / SiO 2 =97.

[0027] The X-ray diffraction pattern of the prepared niobium-silicon molecular sieve is shown in figure 1 , the data show th...

Embodiment 2

[0029] In 90 milliliters of deionized water, add 5.6 grams of 98% (mass percentage) sulfuric acid, add 5 milliliters of niobium oxalate aqueous solution (5% mass percent of hydrated niobium oxide content), template agent tetrapropyl ammonium bromide (TPABr) 10 grams, fluoride Ammonium 8.5 grams, add 30% (SiO 2 Weight) 42 grams of silica sol, stirred evenly, the pH of the reaction mixture=6.0, stirred and homogenized for 2 hours, transferred to a stainless steel crystallization reactor with polytetrafluoroethylene lining, crystallized at 180 ° C under autogenous pressure After 24 hours, the obtained crystallized product was filtered, washed, and dried to obtain 12.5 grams of molecular sieve powder, and then roasted at 500°C for 5 hours to obtain niobium-silicon molecular sieves. The molar composition of the reaction mixture was: SiO 2 / Nb 2 o 5 =75, TPABr / SiO 2 =0.18, F - / SiO 2 = 1.1, H 2 O / SiO 2 =33.

Embodiment 3

[0031] Add 3.6 grams of ammonium fluoride, 3 grams of oxalic acid, and 1 gram of ammonium niobium oxalate complex in 120 milliliters of deionized water, heat to dissolve, add 10 grams of template agent tetrapropylammonium bromide (TPABr) and 12 grams of white carbon black , stirred evenly, the pH of the reaction mixture = 6.3, stirred and homogenized for 5 hours, transferred to a stainless steel crystallization reaction kettle with a polytetrafluoroethylene liner, and crystallized under autogenous pressure at 200 ° C for 48 hours. The product was filtered, washed and dried to obtain 11.5 grams of molecular sieve powder, and then roasted at 550°C for 3 hours to obtain niobium-silicon molecular sieves. The molar composition of the reaction mixture was: SiO 2 / Nb2 o 5 =40, TPABr / SiO 2 =0.18, F - / SiO 2 = 1.1, H 2 O / SiO 2 =40.

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Abstract

The invention relates to a preparation method of a niobium-silicon molecular sieve with MFI structure, which uses silicon source, niobium source, quaternary ammonium salt, fluoride, acid and water as raw materials, and said silicon source is selected from silica sol, silica gel, white carbon Black or its mixture, the niobium source is selected from niobium oxide, niobium oxalate, niobium oxalate ammonium complex or its mixture, the acid is oxalic acid or sulfuric acid, the quaternary ammonium salt is tetrapropylammonium bromide, the fluoride is ammonium fluoride, the reaction The molar composition of the raw materials of the system conforms to the following ratio: SiO2 / Nb2O5=18~75, R / SiO2=0.17~0.18, F- / SiO2=1.0~1.1, H2O / SiO2=33~97, wherein R is a quaternary ammonium salt, the reaction The pH value of the system is 6-8, and the raw materials are mixed according to the above ratio to form a reaction mixture, which is placed in a crystallization reactor for crystallization, and then filtered, washed, dried, and roasted to obtain niobium-silicon molecular sieves. The method of the invention has cheap and easy-to-obtain raw materials, low template dosage, can directly obtain hydrogen-type molecular sieves, does not need ammonium exchange post-treatment process, reduces environmental pollution, and makes the prepared niobium-silicon molecular sieves relatively low in cost and relatively simple in preparation steps.

Description

technical field [0001] The invention relates to a method for preparing a niobium-silicon molecular sieve, in particular to a method for preparing a niobium-silicon molecular sieve with an MFI structure. Background technique [0002] Introducing transition metal elements into molecular sieves, combining the performance of molecular sieves with the catalytic properties of transition metals can produce unique catalytic effects. The prepared molecular sieves containing heteroatoms not only have conventional acidic active centers, but also have special properties such as redox , so it has been widely studied, and heteroatoms can enter the molecular sieve framework with four coordination under certain conditions, just like the conventional silica-alumina molecular sieves. [0003] In recent years, niobium-containing materials have shown some special properties in the field of catalysis, such as excellent water resistance, excellent stability, and have...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J29/00C01B37/00C01B39/08
Inventor 金照生许茗喆
Owner CHINA PETROLEUM & CHEM CORP