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Silicide compositions containing alkali metals and methods of making the same

A technology of alkali metal silicide and composition, which is applied in the production of metal silicide, hydrogen, phosphate material processing, etc.

Inactive Publication Date: 2007-09-05
SIGNA CHEM INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Severe restrictions are placed on storage and handling of NaSi without keeping it in vacuum or under an inert atmosphere to avoid its inherent hazards

Method used

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  • Silicide compositions containing alkali metals and methods of making the same
  • Silicide compositions containing alkali metals and methods of making the same
  • Silicide compositions containing alkali metals and methods of making the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0039] In each of the following examples, an easily evacuable Erlenmeyer flask was used to prepare samples of alkali metal silicide materials. Insert the silicon into the flask and connect it to the vacuum line with UltraTorr fittings and Kontes vacuum valve. The flask was then heated with a flame under vacuum and inserted into a glove box filled with helium, where sodium blocks had been added. After taking it out of the box, the flask was evacuated again and the sodium lumps were melted. When the pressure stabilizes at about 3×10 -5 After holding, seal the tube from above the flask, and heat the flask and its contents in an oven at the desired reaction temperature overnight or longer. When the reaction is complete, the flask is inserted into the glove box again, the soldered pins are broken, and the contents are taken out and stored for further study.

[0040] Example 1-Initial Test

[0041] Although it is known that Na reacts with borosilicate glass at temperatures exceeding 300...

Embodiment 2

[0046] Example 2-Stability in air

[0047] During the process, the Na-Si material of the present invention immediately reacts with water to generate hydrogen gas and release heat. However, the material is completely unreactive to dry oxygen for at least one day. Unless the relative humidity is high, the powder can be weighed in the air or transferred from one container to another. The sample is exposed to the laboratory air in the aluminum weighing pan, but reacts slowly with moisture. After 2 hours, adding a small amount of liquid water, the black block immediately precipitated hydrogen. It may be that the method of preparing the composition of the invention described herein produces an alkali metal silicide protected by a surface layer of silicon dioxide or some other composition. In any case, the resulting material is easy to handle in air, which creates the ability to generate hydrogen when needed.

[0048] These results indicate that it can directly produce silicides that may...

Embodiment 3-500

[0049] Example 3-Reaction between sodium and silicon powder at 500°C

[0050] The sample Na-Si-1 was prepared by introducing 0.56 g of powdered crystalline silicon (Alfa Aesar, 325 mesh) into an easily evacuable Erlenmeyer flask. After degassing with a gas-oxygen torch (~300°C) under vacuum, the flask was placed in a helium-filled glove box, and 0.46 g of sodium metal was added. After evacuating and melting the sodium, the bottle neck was sealed under vacuum, and the flask and contents were heated in a furnace for 2 hours at 300°C, 22 hours at 400°C, and 48 hours at 500°C. The Pyrex flask turned dark brown-red in the process, and the product consisted of powder and a small amount of lumps. In the glove box, 0.66 g of product was recovered. When water was added, the 24.5 mg sample produced 0.517 millimoles (mmol) of hydrogen. This corresponds to 0.0423kg H 2 / kg sample. If hydrogen is produced only by sodium silicide, the quantity corresponds to 43% Na 4 Si 4 .

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PUM

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Abstract

The invention relates to Group 1 metal / silica gel compositions comprising silica gel and an alkali metal or an alkali metal alloy. The compositions of the inventions are described as Stage 0, I, II, and III materials. These materials differ in their preparation and chemical reactivity. Each successive stage may be prepared directly using the methods described below or from an earlier stage material. Stage 0 materials may, for example, be prepared using liquid alloys of Na and K which are rapidly absorbed by silica gel (porous Si02) under isothermal conditions, preferably at or just above room temperature, to form loose black powders that retain much of the reducing ability of the parent metals. When the low melting Group 1 metals are absorbed into the silica gel, a mild exothermic reaction produces Stage I material, loose black powders that are indefinitely stable in dry air. Subsequent heating to 400 DEG C produces Stage II materials, which are also loose black powders. Further heating above 400 DEG C forms Stage III material with release of some Group 1 metal. It is believed that Stage I, II and III materials represent reductions of the silica gel after absorption of the Group 1 metal. Preferred Group 1 metal / silica gel compositions of the invention are those containing sodium, potassium, or sodium-potassium alloys with sodium and sodium- potassium alloys being most preferred. Each stage of the Group 1 metal / silica gel composition of the invention may be used as a reducing agent reacting with a number of reducible organic materials in the same manner known for alkali metals and their alloys.

Description

[0001] Related application materials [0002] This application claims the priority rights of the provisional application serial number 60 / 578818 filed on June 14, 2004 and 60 / 667693 filed on April 4, 2005, the entire contents of which are incorporated herein by reference. Invention field [0003] The present invention relates to an alkali metal silicide composition prepared by the interaction of an alkali metal and silicon at a temperature below about 475°C. The composition provides a stable source of reduced water and produces a source of pure hydrogen. Background of the invention [0004] Alkali metals are very active in their metallic or neutral state. Alkali metals are very reactive to air and moisture and can spontaneously catch fire when exposed to these agents. In order to avoid the inherent hazards associated with their reactivity, neutral metals must often be stored in a vacuum or in an inert liquid such as oil in order to prevent it from contacting the atmosphere that ma...

Claims

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Application Information

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IPC IPC(8): C01B25/01C01B3/08C01B33/06
CPCC01B3/08C01B33/06C01B3/06Y02E60/364Y02E60/36
Inventor M·莱芬费尔德J·L·戴
Owner SIGNA CHEM INC
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