A method for preparing acetylene in a laboratory using a drip-type gas generator

Abstract

The present invention discloses a method for preparing acetylene in a laboratory using a drip-type gas generator. The method uses any one of a hydrochloric acid aqueous solution, an acetic acid aqueous solution, and an ammonium chloride aqueous solution as a reaction liquid, utilizes the drip-type gas generator as a reaction device, and adds any one of glass beads, platinum beads, plastic balls, and stainless steel balls with a diameter of 2 to 10 mm, which is non-reactive with the reaction liquid, to form a gap in the reaction vessel. The paste-like precipitate produced by the reaction is flushed into a waste liquid tank by the reaction waste liquid, thereby reducing the wrapping of the paste-like precipitate on the calcium carbide, allowing sufficient contact between the reactants and greatly improving the gas production efficiency. During the reaction process, the piston can be opened at any time according to the experimental needs to release the waste liquid, thereby achieving solid-liquid separation, achieving the purpose of controlling the reaction rate, and ensuring the safety of the experiment. The present invention can be used for acetylene preparation experimental teaching in university and middle school chemistry, and can also be used for scientific research experiments requiring acetylene as a raw material.

Description

Technical Field

[0001] The invention relates to the technical field of acetylene gas preparation, and in particular to preparing acetylene gas in a laboratory by utilizing a drip-type gas generator. Background Art

[0002] Acetylene, commonly known as air coal or calcium carbide gas, is a colorless gas at room temperature and pressure. It is slightly soluble in water and presents a risk of violent explosion in liquid, solid, or gaseous form under certain pressures. Acetylene is a fundamental raw material for the manufacture of acetaldehyde, acetic acid, benzene, synthetic rubber, and synthetic fibers. It is also used industrially for lighting, welding, and metal cutting (oxyacetylene flames). In high school chemistry and university organic chemistry, a separatory funnel and distilling flask are typically used as the reaction vessel to produce acetylene by reacting saturated salt water with calcium carbide. However, in actual practice, even when using saturated salt water instead of water, problems persist, including excessive reaction speed, unstable acetylene gas flow, difficulty in observing and controlling the reaction process, and the resulting paste of calcium hydroxide, which can easily clog the glass tube. This can lead to excessive gas and pressure within the bottle, forcing the rubber stopper to eject, damaging the instrument, and even injuring the experimenter. To address these issues, Liu Ping and others designed a compact and lightweight integrated experimental device for acetylene preparation, purification, and property experiments based on the principle of two-way control. Wei Xinping and others used a combination of disposable plastic droppers and test tubes to conduct experiments, replacing saturated salt water with a mixture of saturated copper sulfate and anhydrous ethanol. This miniaturized, low-cost, and ready-to-use experimental device was achieved. Li Junsheng optimized the experimental device and operating methods by wrapping cotton soaked in saturated salt water around wire and adsorbing it with a magnet, controlling the reaction process by adjusting the position of the magnet. Peng Xianchun experimented with the reactions of solutions such as acetone, sodium hydroxide, and acetic acid with calcium carbide, concluding that a volume ratio of approximately 1:3 between acetic acid and calcium carbide could effectively control gas generation. These improvements optimized the acetylene preparation experiment to varying degrees, but did not completely resolve the existing problems.

[0003] A drip-type gas generator is a solid-liquid reaction device consisting of a liquid reservoir, a flow regulator, an exhaust pipe, and a reaction vessel. The flow regulator controls the dripping of the reactant solution, ensuring full contact between the reactant and the solid reactants in the reaction vessel. Reaction liquid can be added to the reservoir at any time during the reaction. At the end of the reaction, the flow regulator is closed and the piston is opened to discharge the waste liquid. This device can produce the appropriate amount of gas according to experimental needs, addressing the shortcomings of traditional Kipp generators, such as excessive gas production and waste of reagents. It is currently used in teaching and scientific research experiments with gases such as H2, O2, and CO2. Experimental results demonstrate that the drip-type gas generator features high reagent utilization efficiency, excellent safety performance, and easy operation. Therefore, using a drip-type gas generator to produce acetylene gas is of great significance to both experimental teaching and scientific research. Summary of the Invention

[0004] The present invention aims to address the problems of excessively fast reaction rates, uncontrollable reaction progress, unstable gas flow, and foam clogging conduits in laboratory acetylene production. The present invention provides a method for preparing acetylene gas in the laboratory using a drip-type gas generator. Compared to a production device consisting of a constant-pressure separatory funnel and a distillation flask, this method boasts a smaller chamber, easier operation, higher gas production capacity, and significantly improved gas production efficiency, making it suitable for application in experimental teaching and scientific research.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention consists of the following steps:

[0006] Step 1: Add lump calcium carbide and a solid dopant that does not react with the reaction solution into a reaction vessel, add the reaction solution into a liquid storage cup, add a saturated copper sulfate aqueous solution into a test tube, and invert the test tube filled with water in a water tank; the reaction solution is any one of hydrochloric acid aqueous solution, acetic acid aqueous solution, and ammonium chloride aqueous solution;

[0007] Step 2: Open the flow regulator and allow the acidic reaction liquid to drip into the reaction vessel and contact with calcium carbide to generate gas. After the gas passes through a saturated copper sulfate aqueous solution, acetylene is collected in a test tube.

[0008] Furthermore, the concentration of the hydrochloric acid aqueous solution is preferably 2 to 4 mol / L.

[0009] Furthermore, the concentration of the acetic acid aqueous solution is preferably 2 to 3 mol / L.

[0010] Furthermore, it is preferred that the concentration of the aqueous ammonium chloride solution is 2 to 2.5 mol / L.

[0011] Furthermore, it is preferred that the solid dopant is any one of glass beads, platinum beads, plastic balls, and stainless steel balls, and the diameter of the solid dopant is 2 to 10 mm.

[0012] Furthermore, it is preferred that the weight of the calcium carbide and the volume ratio of the solid dopant be 1g:1-4cm 3 .

[0013] Compared with the prior art, the present invention has the following beneficial technical effects:

[0014] 1. The present invention uses a drip-type gas generator as a reaction device. Glass beads, platinum beads, plastic balls, and stainless steel balls with a diameter of 2 to 10 mm are added to the reaction vessel to form a gap, so that the paste precipitate produced by the reaction is flushed into the waste liquid tank by the reaction waste liquid. During the reaction, the piston can be opened at any time according to experimental needs to release the waste liquid, thereby achieving solid-liquid separation and achieving the purpose of controlling the reaction process.

[0015] 2. The drip-type gas generator device used in the present invention is simple and easy to operate. The weak acidity of acidic aqueous solutions such as hydrochloric acid aqueous solution, acetic acid aqueous solution, and ammonium chloride aqueous solution can reduce the wrapping of paste-like precipitation on calcium carbide, so that the reactants are fully in contact with each other, the gas production efficiency is high, the gas production volume is large, and the average acetylene gas yield can reach 90%;

[0016] 3. The present invention uses hydrochloric acid aqueous solution, acetic acid aqueous solution, ammonium chloride aqueous solution, etc. as the reaction liquid, which greatly reduces the reaction rate. At the same time, the acidity of the reaction liquid can reduce the influence of Ca(OH)2 foam, avoid its clogging of the catheter, and ensure the safety of the experiment.

[0017] 4. The present invention utilizes the weak acidity of acidic aqueous solutions such as hydrochloric acid aqueous solution, acetic acid aqueous solution, and ammonium chloride aqueous solution to eliminate a large amount of calcium hydroxide precipitation and reduce the generation of foam. The addition of solid dopants facilitates solid-liquid separation, and the experimental effect is good.

[0018] 5. The method of the present invention can be used as an experiment for university students, a demonstration experiment teaching in middle schools and a scientific research application for teachers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of a drip-type gas generator.

[0020] Figure 2 The invention discloses an experimental device for preparing acetylene in a laboratory by using a drip-type gas generator. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to these examples.

[0022] The present invention first uses a drip-type gas generator to prepare acetylene gas, then uses a saturated copper sulfate aqueous solution to remove impurities in the acetylene gas, and finally collects the acetylene gas for purity testing. Figure 1 As shown in FIG. 1 , the droplet generator used in the present invention includes a reaction vessel 1, a liquid storage cup 2, a flow regulator 3, an exhaust pipe 4, a sieve plate 5, a waste liquid tank 6, and a piston 7. In addition to the droplet generator, the experimental device used in the laboratory preparation of acetylene using the droplet gas generator of the present invention also includes Figure 2 The shown test tube 8, water tank 9 and test tube 10. The exhaust pipe 4 is connected to the test tube 8 through a latex tube, and the test tube 8 is connected to the air guide tube in the test tube 10 through a latex tube.

[0023] Before the experiment, check the air tightness of the device. Add distilled water to the liquid storage cup 2 and the test tube 8 respectively. Figure 2Connect the experimental equipment in sequence. Adjust the flow regulator 3 and slowly drip distilled water into the reaction vessel 1. If you can see uniform small bubbles emerging from the water surface of the support test tube 8, it means that the device is airtight. Then, add soybean-sized calcium carbide and solid dopants that do not react with the reaction liquid to the dry drip gas generator, add the reaction liquid to the liquid storage cup 2, add a saturated copper sulfate aqueous solution to the support test tube 8, and turn the water-filled test tube 10 upside down in the water tank 9. Since calcium carbide is often mixed with impurities such as CaS, Ca3As2, and Ca3P2, the saturated copper sulfate aqueous solution is used as a scrubbing solution to remove impurity gases such as H2S, AsH3, and PH3 produced by the reaction. The solid dopant that does not react with the reaction solution is any one of glass beads, platinum beads, plastic balls and stainless steel balls with a diameter of 2 to 10 mm. The reaction solution is any one of hydrochloric acid aqueous solution, acetic acid aqueous solution and ammonium chloride aqueous solution. The concentration of the hydrochloric acid aqueous solution is 2 to 4 mol / L, the concentration of the acetic acid aqueous solution is 2 to 3 mol / L, and the concentration of the ammonium chloride aqueous solution is 2 to 2.5 mol / L. The weight ratio of the calcium carbide to the volume of the solid dopant is 1 g: 1 to 4 cm 3 Finally, acetylene is produced and collected. Flow regulator 3 is opened, allowing the reaction solution to drip into reaction vessel 1 and fully contact the calcium carbide to generate gas. The generated gas is first passed through a saturated copper sulfate aqueous solution to remove impurities such as H2S. Finally, the acetylene gas is collected using the drainage method. The waste liquid after the reaction flows through sieve plate 5 and piston 7 into waste liquid tank 6.

[0024] Example 1

[0025] Step 1: Add 3.0g of soybean-sized calcium carbide and 12cm 3 A mixture of glass beads with a diameter of 7 mm is prepared. A 2 mol / L aqueous solution of ammonium chloride is added to the liquid storage cup 2. A 1 / 3 volume of a saturated aqueous solution of copper sulfate is added to the test tube 8. The test tube 10 filled with water is then turned upside down in the water tank 9.

[0026] Step 2: Open flow regulator 3 and allow aqueous ammonium chloride to drip into reaction vessel 1 at a rate of 2 to 3 drops per second. This aqueous ammonium chloride solution fully contacts the calcium carbide, generating gas. The generated gas is then passed through a saturated aqueous copper sulfate solution to remove impurities such as H2S. Finally, acetylene is collected using test tube 10. During the reaction, the reactor walls are warm, the airflow is stable, and a small amount of off-white precipitate and foam are produced, making solid-liquid separation easy. The calculated acetylene yield is 93.35%. However, using a production apparatus consisting of a constant pressure separatory funnel and a distillation flask, the yield of acetylene produced by reacting calcium carbide with saturated salt water is only 83.61%.

[0027] Example 2

[0028] The ammonium chloride aqueous solution in Example 1 was replaced with a 2.5 mol / L acetic acid aqueous solution, and the amounts of other reactants and the steps remained unchanged. It was found that the reactor wall was warm, the airflow was smooth, a small amount of off-white Ca(OH)2 precipitate and foam were generated, and solid-liquid separation was easy to achieve.

[0029] Example 3

[0030] The ammonium chloride aqueous solution in Example 1 was replaced by a 2 mol / L hydrochloric acid aqueous solution, and the amounts of other reactants and the steps remained unchanged. It was found that the reactor wall was warm, the airflow was smooth, a small amount of off-white Ca(OH)2 precipitate and foam were generated, and solid-liquid separation was easy to achieve.

[0031] Example 4

[0032] The glass beads with a diameter of 7 mm in Example 1 were replaced with platinum beads, plastic balls or stainless steel balls, and the amounts of other reactants and steps remained unchanged. The experimental phenomena of warm reactor walls, smooth airflow, a small amount of off-white precipitate and a small amount of foam were all observed, and solid-liquid separation was easily achieved.

[0033] Example 5

[0034] The weight of calcium carbide in Example 1 was adjusted to 1.0 g, 2.0 g, 4.0 g, 5.0 g, 6.0 g, and 7.0 g, and glass beads were reduced or increased accordingly so that the ratio of calcium carbide weight to glass beads volume was always maintained at 1 g:4 cm 3 The amounts of other reactants and the steps remained unchanged, and the experimental phenomena of warm reactor walls, smooth airflow, a small amount of gray-white precipitate and a small amount of foam were all observed, and the acetylene yield was above 85%.

[0035] Comparative Example 1

[0036] The ammonium chloride aqueous solution in Example 1 was replaced with distilled water, and the amounts of other reactants and steps remained unchanged. It was found that the reactor wall was hot, heat was released more, the gas production rate was faster, the airflow was not smooth, there was off-white Ca(OH)2 precipitation and foam generation, and it was difficult to achieve solid-liquid separation.

[0037] Comparative Example 2

[0038] The ammonium chloride aqueous solution in Example 1 was replaced with saturated brine, and the amounts of other reactants and steps remained unchanged. It was found that the reactor wall was hot, heat was released, the gas production rate was fast, the airflow was not smooth, there was off-white Ca(OH)2 precipitation and foam generation, and it was difficult to achieve solid-liquid separation.

[0039] Comparative Example 3

[0040] All the glass beads with a diameter of 7 mm in Example 1 were replaced with calcium carbide blocks the size of soybeans. The amounts of other reactants and the steps remained unchanged. It was found that the reactor wall was hot, heat was released more, the gas production rate was faster, the airflow was not smooth, there was grayish white Ca(OH)2 precipitation and foam generation, and it was difficult to achieve solid-liquid separation.

Claims

1. A method for preparing acetylene in a laboratory using a drip-type gas generator, characterized in that The method consists of the following steps: Step 1: Add bulk calcium carbide and a solid dopant that does not react with the reaction solution into a reaction container (1), add the reaction solution into a liquid storage cup (2), add a saturated copper sulfate aqueous solution into a test tube (8), and turn the test tube (10) filled with water upside down in a water tank (9); the reaction solution is any one of a 2-4 mol / L hydrochloric acid aqueous solution, a 2-3 mol / L acetic acid aqueous solution, and a 2-2.5 mol / L ammonium chloride aqueous solution; the solid dopant is any one of a glass bead, a platinum bead, a plastic ball, and a stainless steel ball, the diameter of the solid dopant is 2-10 mm, and the weight of the calcium carbide to the volume of the solid dopant is 1 g:1-4 cm 3 ; Step 2: Open the flow regulator (3) and allow the acidic reaction liquid to drip into the reaction container (1) to contact with calcium carbide to generate gas. The gas passes through a saturated copper sulfate aqueous solution and acetylene is collected using a test tube (10).

Images