"Research and Practice: Understanding the History of Soda Ash Production" Sodium and its Compounds PPT

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"Research and Practice: Understanding the History of Soda Ash Production" Sodium and its Compounds PPT

Part One: [Material Reading]

Material 1: Lubulan alkali production method

In 1783, the French Academy of Sciences offered a high reward of 1,200 francs for the method of making soda ash. In 1789, Lou Blanc, the attendant doctor to the feudal Duke of Orleans in France, successfully created a method of making alkali. He obtained a patent in 1791 and established an alkali plant with a daily output of 250 to 300 kg. In addition to salt, the raw materials used in Lubulan's alkali production method include concentrated sulfuric acid, charcoal and limestone. Its production process is as follows:

①The first step: Use concentrated sulfuric acid to convert table salt into sodium sulfate: 2NaCl+H2SO4 (concentrated)====Na2SO4+2HCl↑.

②Step 2: Heat sodium sulfate, charcoal, and limestone in the furnace. The reaction between sodium sulfate and charcoal in the furnace generates sodium sulfide and carbon monoxide: Na2SO4+4C====Na2S+4CO↑.

③The third step: Sodium sulfide reacts with limestone to generate sodium carbonate and calcium sulfide: Na2S+CaCO3====Na2CO3+CaS.

Material 2: Solvay alkali production method

In 1861, the Belgian Solvay used salt, limestone and ammonia as raw materials.

Sodium carbonate and calcium chloride are obtained, which is the ammonia-alkali method. The reaction steps are as follows:

NaCl+NH3+CO2+H2O====NaHCO3+NH4Cl,CaCO3====CaO+CO2↑,2NH4Cl+CaO====2NH3↑+CaCl2+H2O,

2NaHCO3====Na2CO3+CO2 +H2O.

The CO2 and NH3 generated by the reaction can be reused as raw materials.

The total reaction formula is CaCO3+2NaCl ====CaCl2+Na2CO3

This alkali production method has a low raw material utilization rate and produces a large amount of by-product CaCl2 with low use value.

Material three: Hou's method of making alkali

The combined soda ash production method, also known as the Hou's soda ash production method, is used to produce soda ash (Na2CO3) in industry. It was invented by Hou Debang in 1943 and is a soda ash production method widely used in the world. The specific process is: in saturated ammonia salt water (a solution in which ammonia and sodium chloride are both saturated), carbon dioxide is introduced and the following reaction occurs: The chemical equation of the reaction is:

(1)NH3+H2O+CO2====NH4HCO3.

(2)NH4HCO3+NaCl====NH4Cl+NaHCO3↓.

(3)2NaHCO3====Na2CO3+H2O+CO2↑.

The sodium bicarbonate in the reaction precipitates due to low solubility, and can be further calcined and decomposed into sodium carbonate, water and carbon dioxide, of which the carbon dioxide can be re-entered into the reaction for reuse.

Research and practice to understand the production history of soda ash PPT, the second part of the content: [Thinking about improvement]

1. The Lubulan alkali production method has created a historical precedent and made outstanding contributions to mankind, but it also has many shortcomings. What do you think are its shortcomings?

Tips: (1) The main production process is carried out in the solid phase, making it difficult to produce continuously; (2) Concentrated sulfuric acid is required as raw material, and the equipment is severely corroded; (3) The product quality is impure, and calcium sulfide is not easily soluble in water and precipitates into slag. Discarded, the raw materials are not fully utilized and the cost is high; (4) HCl, CO and other gases are generated, causing environmental pollution.

2. What are the advantages of the Solvay alkali production method compared to the Lubrand alkali production method? Is there anything that needs improvement?

Tips: (1) Advantages: The ammonia-alkali method enables continuous production, the utilization rate of salt is greatly improved, and the product is relatively pure, so it is called soda ash, but the biggest advantage is its low cost.

(2) Disadvantages: The utilization rate of raw materials is low, and a large amount of by-product CaCl2 with low use value is produced.

3. Compared with Solvay’s alkali production method, what improvements have been made to Hou’s alkali production method?

Tip: In view of the low salt utilization rate, high cost of soda production, waste liquid and waste residue polluting the environment and being difficult to handle when producing soda ash by the Solvay alkali production method, Mr. Hou Debang successfully developed the joint soda production method in 1943 after thousands of experiments. Law. This new process is to build an ammonia plant and an alkali plant together for joint production. The ammonia plant provides the ammonia and carbon dioxide needed by the alkali plant. The ammonium chloride in the mother liquor is crystallized by adding salt and used as a chemical product or fertilizer. The salt solution can be recycled again. The "joint" in the so-called "joint alkali production method" means that this method combines the ammonia synthesis industry and the alkali production industry, utilizes CO2, a by-product of ammonia production, eliminates the use of limestone decomposition for production, and simplifies production equipment. In addition, the combined alkali production method also avoids calcium chloride, a by-product of little use in the ammonia-alkali production method, and uses ammonium chloride that can be used as fertilizer to recover it, which improves the utilization rate of salt, shortens the production process, and reduces the impact on the environment. pollution, reducing the cost of soda ash.

Research and practice to understand the production history of soda ash PPT, the third part: [Migration Application]

Hou's alkali production method was independently invented by Hou Debang, a Chinese chemical engineering expert, in 1943. It broke the foreign technological blockade at that time. A chemistry group simulated Hou's alkali production method, using NaCl, NH3, CO2 and water as raw materials and the device as shown in the figure to produce NaHCO3. The chemical equation of the reaction is:

NH3+CO2+H2O+NaCl====NaHCO3+NH4Cl. Then NaHCO3 is made into Na2CO3.

(1) The function of device B is __________.

(2) When preparing Na2CO3 from NaHCO3 produced in device C, the experimental operations required include ________, washing and burning. The chemical equation for preparing Na2CO3 from NaHCO3 is _______________.

(3) When preparing NaHCO3 by Hou's alkali production method, NH3 should be passed through first and then CO2 for the purpose of ____________________.

[Analysis] (1) Device A is a generating device for preparing carbon dioxide gas. The generated carbon dioxide gas contains hydrogen chloride gas, which affects the preparation of sodium bicarbonate. The function of device B is to absorb hydrogen chloride gas; the final tail gas contains ammonia gas. It cannot be discharged into the air, and exhaust gas absorption needs to be carried out; (2) The reaction of NaHCO3 produced in device C is NH3+CO2+H2O+NaCl====NaHCO3↓+NH4Cl; when preparing Na2CO3, it is necessary to filter and obtain crystals and wash them After heating and burning, sodium carbonate is obtained. (3) Ammonia gas has high solubility in water. Passing ammonia gas first can absorb more CO2 and increase the generation rate of HC.

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Update Time: 2024-10-03

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