A method for synthesizing high-purity δ-layered sodium disilicate from silicon tetrachloride

A technology of silicon tetrachloride and sodium disilicate, applied in the direction of silicate, chlorine/hydrogen chloride, alkali metal silicate, etc., to achieve simple production process, high utilization value, good calcium and magnesium ion exchange capacity and buffer capacity Effect

Active Publication Date: 2015-08-19
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, this method has not been reported at home and abroad

Method used

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  • A method for synthesizing high-purity δ-layered sodium disilicate from silicon tetrachloride
  • A method for synthesizing high-purity δ-layered sodium disilicate from silicon tetrachloride
  • A method for synthesizing high-purity δ-layered sodium disilicate from silicon tetrachloride

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (A) Take 31.4ml of pure water and place it in a 150ml Erlenmeyer flask, and evenly drop 10ml of silicon tetrachloride into the pure water with an autosampler at a rate of 1.5ml / min. The molar ratio is 1:20 (4 times excess water);

[0028] (B) Separate the product of step (A) with a suction filtration device, recover the filtrate as hydrochloric acid after concentration, and transfer the filter residue (ortho silicic acid) to a 50ml nickel crucible;

[0029] (C) Weigh 3.48g of NaOH solid and add it into a 50ml nickel crucible so that SiO 2 / Na 2 The O modulus is 1.9-2.1; after mixing the reactants, place the nickel crucible in a muffle furnace at 850°C for calcination for 1 hour, take out the nickel crucible and cool it to obtain solid sodium silicate;

[0030] (D) Take 15ml of pure water and add it to a 50ml beaker, heat to 80°C, transfer the solid sodium silicate in step (C) to the beaker to dissolve; use a suction filter to separate the product, filter residue (unre...

Embodiment 2

[0034] (A) Take 12.56ml of pure water and place it in a 150ml Erlenmeyer flask, and evenly drop 10ml of silicon tetrachloride into the pure water with an autosampler at a rate of 1ml / min. The moles of silicon tetrachloride and water The ratio is 1:8 (1 times excess water);

[0035] (B) Separate the product of step (A) with a suction filtration device, recover the filtrate as hydrochloric acid after concentration, and transfer the filter residue (ortho silicic acid) to a 50ml nickel crucible;

[0036] (C) Weigh about 3.48g of NaOH solid and add it into a 50ml nickel crucible so that SiO 2 / Na 2 The O modulus is 1.9-2.1; after mixing the reactants, place the nickel crucible in a muffle furnace at 800°C for calcination for 2 hours, take out the nickel crucible and cool it to obtain solid sodium silicate;

[0037] (D) Take 15ml of pure water and add it to a 50ml beaker, heat to 70°C, transfer the solid sodium silicate in step (C) to the beaker to dissolve; use a suction filter t...

Embodiment 3

[0041] The steps are the same as in Example 1, except that the high-temperature calcination temperature in step (F) is 650°C.

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Abstract

A method for synthesizing delta-layered sodium disilicate by silicon tetrachloride comprises the following steps: hydrolyzing silicon tetrachloride, carrying out pumping filtration and separation to respectively obtain a hydrochloric acid filtrate and an orthosilicic acid filter residue; mixing orthosilicic acid and sodium hydroxide and calcining to obtain solid sodium silicate; dissolving solid sodium silicate in hot water and filtering to obtain a liquid sodium silicate filtrate; carrying out spray drying on liquid sodium silicate at 150-250 DEG C to obtain amorphous powdery sodium disilicate; and uniformly mixing powdery sodium disilicate and 5-20% of delta-layered sodium disilicate seed crystal with the particle size being 0.04-0.1mm, and carrying out high-temperature roasting and crystallization in a muffle furnace of 650-750 DEG C for 10-60min so as to finally prepare delta-layered sodium disilicate. According to the method, the industrial waste silicon tetrachloride is used as a raw material such that safe treatment of a photovoltaic by-product is guaranteed and valuable delta-layered sodium disilicate and hydrochloric acid are also synthesized. The method is a green chemical reaction pathway. The method requires a simple production technology. Purity of the synthesized product delta-phase crystal can reach 95%, degree of crystallization can reach 90%, and the product has good calcium and magnesium ion exchange capacity and buffer capacity.

Description

technical field [0001] The invention belongs to the technical field of resource treatment and disposal of silicon tetrachloride, a by-product of the photovoltaic industry, and specifically relates to a method for synthesizing high-purity delta-layered sodium disilicate from silicon tetrachloride. Background technique [0002] As the direct raw material for the production of photovoltaic cells, polysilicon production has continued to rise with the rapid development of the photovoltaic industry in the past 10 years. In 2011, the domestic production of polysilicon has reached 75,000 tons. However, every ton of polysilicon produced will produce 18 tons of silicon tetrachloride as a by-product, and the boiling point of silicon tetrachloride is only 70°C. It is easily hydrolyzed in the air to form hydrochloric acid mist, which is extremely corrosive and toxic. Included in the "Inventory of Hazardous Chemicals (2012)" Class 8 Subclass 1. According to the regulations in the "Nation...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/32C01B7/01
Inventor 蒋建国颜枫
Owner TSINGHUA UNIV
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