carbon dioxide

[èr yǎng huà tàn]

A carbon oxide

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Carbon dioxide, a kind of Carbon oxides ， chemical formula Is CO two , the chemical formula is 44.0095^[1] It is colorless and tasteless under normal temperature and pressure^[2] Or colorless and odorless, but its aqueous solution has slightly sour taste^[3] Of Gas , is also a common greenhouse gases^[4] , or atmosphere 1% (0.03% - 0.04% of the total atmospheric volume^[5] ）。

In terms of physical properties, carbon dioxide boiling point - 56.6 ℃ (527kPa), melting point - 78.5 ℃, density It is more dense than air (under standard conditions) and soluble in water.

In terms of chemical properties, carbon dioxide is not active, thermal stability Very high (only 1.8% decomposition at 2000 ℃), unable to burn, usually does not support combustion, belonging to Acid oxide It has the common property of acid oxide, because it reacts with water to produce carbonic acid , so it is carbonic acid Acid anhydride 。^[2-3]

Carbon dioxide can generally be calcined at high temperature limestone Or limestone and Dilute hydrochloric acid It is prepared by reaction, and is mainly used to refrigerate perishable food (solid) Refrigerant (liquid), manufacture of carbonated soft drinks (gaseous) and Homogeneous reaction Solvent (supercritical state), etc.^[2] The study shows that its toxicity is low concentration The carbon dioxide at high concentration will make animals poisoned.^[6]

On April 13, 2023, xiangshan science conference The 742nd Academic Seminar Convene, Experts pointed out that carbon dioxide utilization technology has great potential 。^[64] As of June 2023, In the past 10 years, global greenhouse gas emissions have reached a "record high", with an annual emissions of 54 billion tons of carbon dioxide 。^[67]

Chinese name: carbon dioxide^[61]
Foreign name: carbon dioxide
Alias: Carbonic acid gas 、 Carbonic anhydride 、 dry ice (solid state)^[7]
chemical formula: CO₂^[61]
molecular weight: forty-four point zero zero nine five^[1]
CAS login number: 124-38-9
EINECS login number: 204-696-9
Melting point: -78.5 ℃ (The melting point of carbon dioxide is measured at a high pressure of 527kPa, and there is no liquid carbon dioxide under normal pressure)
Boiling point: -56.6 ℃ (sublimation)
Water solubility: Less than 0.05% (22.9 ℃)
Appearance: Under normal temperature and pressure, it is a colorless, odorless or colorless gas with slight sour taste

Application: Refrigerate perishable foods, make refrigerants, manufacture carbonated soft drinks, etc
Security description: S9
UN dangerous goods number: one thousand and thirteen
Gaseous density: 1.977g/L（0℃，101.325kPa）
Liquid density: 0.9295kg/L（0℃，101.3485kPa）
Solid density: 1.56kg/L（-79℃）
Three phase point: -56.6℃（517.97kPa）
Preparation method: Preparation by reaction of limestone and dilute hydrochloric acid^[2]
Molecular diameter: 0.35～0.51nm^[9]

catalog

A brief history of research

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In the primitive society, the primitive people felt the existence of carbon dioxide in their life practice. However, due to the limitation of historical conditions, they regarded the invisible and intangible carbon dioxide as a kind of monster rather than a substance that kills without leaving traces.^[10]

In the third century, during the Western Jin Dynasty Zhang Hua (232-300)《 Natural History 》A book records that CaCO three ）As the gas generated in the process of lime (CaO), this gas is the lime kiln gas used to produce carbon dioxide in industry today.^[10]

At the beginning of the 17th century, the Belgian doctor Hermont (i.e Jan Baptist van Helmont , Jan Baptista van Helmont, 1580-1644) found that after burning charcoal, in addition to ash, it also produced some invisible and intangible substances. Through experiments, he confirmed that this kind of carbon dioxide, which he called "the essence of the forest", is a non combustion supporting gas, and confirmed that carbon dioxide is a gas; It was also found that the candle flame would naturally extinguish in the gas, which was the first discovery of the inert nature of carbon dioxide. Soon after, the German chemist Hoffmann (i.e Friedrich Hoffman Friedrich Hoffmann (1660-1742) studied the carbon dioxide gas, which he called "spirit minerals", and concluded for the first time that the carbon dioxide aqueous solution was weakly acidic.^[10]

In 1756, the British chemist Blake Joseph Black , Joseph Black, 1728-1799) was the first to use quantitative methods to study the carbon dioxide gas he called "fixed air", and carbon dioxide was called "fixed air" for a period of time thereafter.^[11]

In 1766, British scientist Cavendish (i.e Henry Cavendish Henry Cavendish, 1731-1810.^[12]

In 1772, French scientist Lavoisier Antoine Laurent Lavoisier Antoine Laurent de Lavoisier, 1743-1794) and others used a large fire mirror to focus light to heat the diamond placed in the glass cover on the mercury tank, and found that it would burn, and its product was "fixed air". In the same year, the scientist Priestley (i.e Joseph Priestley , Joseph Priestley, 1733-1804) found that the pressure is conducive to the dissolution of "fixed air" in water, while the increase of temperature is not conducive to its dissolution. This discovery enables carbon dioxide to be used in the artificial production of carbonated water（ Soda ）。^[12]

In 1774, Swedish chemist Bergman (i.e Torbern Olof Bergman , Torbern Olof Bergman, 1735-1784) described his research achievements on the density of "fixed air", its solubility in water, its effect on litmus, its absorption by alkali, its existence in air, and the dissolution of aqueous solution on metal zinc and iron in his paper Research on Fixed Air.^[11]

In 1787, Lavoisier published a statement about the "fixed air" generated after burning charcoal in oxygen, affirming that "fixed air" is composed of carbon and oxygen, and was renamed "carbonic acid gas" because it is a gas. At the same time, Lavoisier also measured the mass ratio of carbon to oxygen (23.4503% carbon and 76.5497% oxygen), revealing the composition of carbon dioxide for the first time.^[10-11]

In 1797, Smitbson Tennant, a British chemist,^[13] Translated into "Tenet"^[14] The "fixed air" contains 27.65% carbon and 72.35% oxygen by analysis.^[10]

In 1823, the British scientist Faraday Michael Faraday , Michael Faraday, 1791-1867) found that pressurization can liquefy "carbonate gas". In the same year, Faraday and David (i.e humphry davy Humphry Davy (1778-1829, also translated as "Dibi") liquefied "carbonic acid gas" for the first time.^[15-17]

In 1834 or 1835, Adrien Jean Pierre Thilorier (1790-1844), a German, translated "Tyroler" and "Delauliani"^[18] , "Quirrell"^[19] And so on) successfully produce dry ice (solid carbon dioxide).^[20-21]

In 1840, the French chemist Duma (namely Jean Baptiste Andre Duma Jean Baptiste Andr é Dumas, 1800-1884) put the accurately weighed graphite containing pure carbon into sufficient oxygen for combustion, and absorbed the generated "fixed air" with potassium hydroxide solution, and calculated the mass fraction ratio of oxygen and carbon in the "fixed air" as 72.734:27.266. Previously, Avogadro (i.e Amodeo Avogadro Amedeo Avogadro, August 9, 1776-July 9, 1856) put forward the hypothesis in 1811 that "under the same temperature and pressure, any gas of the same volume contains the same number of molecules." Chemists combined the atomic weights of oxygen and carbon to get the number of atoms of oxygen and carbon in "fixed air". The simple integer ratio is 2:1, Based on the hypothesis put forward by Avogadro in 1811, the molecular weight of "fixed air" was measured to be 44 through experiments, thus the chemical formula of "fixed air" was CO two The name corresponding to this chemical formula is "carbon dioxide".^[11]

In 1850, Irish physical chemist Andrews (i.e Thomas Andrews Thomas Andrews, 1813-1885) began to study the supercritical phenomenon of carbon dioxide, and measured two critical parameters of carbon dioxide in 1869: the supercritical pressure was 7.2MPa, and the supercritical temperature was 304.065K (the recognized values of the two in 2013 were 7.375MPa and 303.05K respectively).^[22-23]

In 1896, Swedish chemist Arenius (i.e Swant Auguste Arrenius , Svante August Arrhenius, 1859-1927) pointed out through calculation that doubling the concentration of carbon dioxide in the atmosphere could increase the surface temperature by 5~6 ℃.^[24]

From 1950 to 1952, Soviet Union K.B. ллбавский, H.M. Новожилов and Japan's Kawaguchi Chunjiro respectively studied a kind of welding wire used in carbon dioxide shielding gas, and proposed a new metallurgical scheme for welding steel.^[25] Then, in 1953, Lubavsky and others invented CO2 gas shielded welding 。^[26]

In April 2022, University of Electronic Science and Technology Xiachuan Research group Shenzhen Advanced Technology Research Institute, Chinese Academy of Sciences Yu Tao Research group and University of Science and Technology of China Zeng Jie research group^[57] common adopt Electrocatalysis combination biosynthesis To efficiently reduce carbon dioxide to high concentration acetic acid , which can be further synthesized by microorganisms glucose and Grease , resulting in On April 28, in the form of a cover article in an international academic journal《 Nature · Catalysis 》Publication.^[55-56]

On August 25, 2022, NASA said that the James Webb Space Telescope found clear evidence of carbon dioxide in the atmosphere of exoplanets for the first time According to.^[60]

In September 2023, the Webb Space Telescope detected carbon dioxide on Europa's surface, but analysis shows that these carbon dioxide may originate from Europa's underground ocean.^[68]

molecular structure

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CO ₂ molecular structure	CO ₂ bonding process
CO ₂ molecular structure^[27]	CO ₂ bonding process^[28]

CO two The molecular shape is linear, and its structure was once considered as: O=C=O. But CO two The carbon oxygen bond length in the molecule is 116pm, between carbon oxygen double bond (bond length is 124pm) and carbon oxygen triple bond (bond length is 113pm), so CO two The carbon and oxygen bonds in C have a certain degree of triple bond characteristics.

Modern scientists generally believe that CO two The central atom of the molecule carbon atom takes Sp hybridization , two sp hybrid orbitals overlap with two 2p orbitals (containing one electron) of two oxygen atoms to form two σ bond , the mutually perpendicular p orbitals on the carbon atoms form two parallel p orbitals with the two oxygen atoms respectively Large π bond 。^[27]

Physical and chemical properties

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physical property

Carbon dioxide is a colorless and odorless gas at normal temperature and pressure, which is soluble in most organic solvents such as water and hydrocarbons. Its relevant physical constants are shown in the table below:

nature	Condition or symbol	Company	data
melting point	527kPa	℃	-78.5
boiling point		℃	-56.6
relative density	-79 ℃, water=1		one point five six
Relative vapor density	Air=1		one point five three
Saturated vapor pressure	-39℃	KPa	one thousand and thirteen point two five
critical temperature		℃	thirty-one point three
critical pressure		MPa	seven point three nine
Octanol /Water partition coefficient			zero point eight three
Refractive index	12.5～24℃		1.173～1.999
Molar refractive index			six point nine eight
viscosity	21℃，5.92MPa	Millipascal second (mPa · s)	zero point zero six nine seven
Heat of evaporation	sublimation	KJ/mol	twenty-five point two five
Heat of fusion		KJ/mol	eight point three three
Heat of formation		KJ/mol	three hundred and ninety-four point four zero
Specific heat capacity	20 ℃, constant pressure	KJ/kg Kelvin	two point eight four four eight
Vapor pressure	5.9～14.9℃	MPa	4.05～5.07
Thermal conductivity	12～30℃	Kilvin per meter [W/(m · K)]	0.10048～83.74×10 -7
Coefficient of volume expansion	-50～0℃	Per Kelvin (K -1 ）	zero point zero zero four nine five
Coefficient of volume expansion	0～20ºC	Per Kelvin (K -1 ）	zero point zero zero nine nine one
Molar volume		ML/mol	forty-four point seven
Isotonic capacity	90.2K		sixty point nine
surface tension		Dyne/cm	three point four
Polarizability	ten -24 cm three		two point seven six

(Reference:^[2] ）

chemical property

Carbon dioxide is one of the carbon oxides. It is an inorganic substance, nonflammable, usually does not support combustion, and is non-toxic at low concentrations. It is also the anhydride of carbonic acid, belonging to Acid oxide , with the general property of acid oxide, in which the carbon element Valence It is+4 valence and is in the highest valence state of carbon element, so carbon dioxide has Oxidizability Without Reducibility , but the oxidation is not strong.^[29]

1. General property of acid oxide

1-1. Reaction with water

Carbon dioxide can dissolve in water and react with water to form carbonic acid, while unstable carbonic acid is easy to decompose into water and carbon dioxide. The corresponding chemical reaction equation is:

；

。^[29]

1-2. React with alkaline oxides

Under certain conditions, carbon dioxide can react with alkaline oxides to generate corresponding salts, such as:

；

。^[29]

1-3. Reaction with alkali

① And calcium hydroxide reaction

Adding carbon dioxide to the clarified lime water will make the clarified lime water turbid and generate calcium carbonate Precipitation (this reaction is often used to test carbon dioxide), and the corresponding chemical reaction equation is:

When carbon dioxide is excessive Calcium bicarbonate ：

Step 1:

；

Step 2:

；

Total equation:

。

Due to the high solubility of calcium bicarbonate, it can be found that the precipitation gradually disappears when carbon dioxide is introduced into the turbid lime water for a long time.^[29]

② Reaction with sodium hydroxide

Carbon dioxide will caustic soda For metamorphism, the corresponding chemical reaction equation is:

When carbon dioxide is excessive sodium bicarbonate ：

Step 1:

；

Step 2:

；

Total equation:

。^[29]

2. Weak oxidation

2-1. Carbon reduction

At high temperature, carbon dioxide can react with carbon element to form carbon monoxide , the corresponding chemical reaction equation is:

。^[29]

2-2. Reduction of magnesium

Magnesium burns in carbon dioxide

Under the condition of ignition, the magnesium strip can be burned in carbon dioxide, and the corresponding chemical reaction equation is:

。^[29]

2-3. Hydrogenation reduction

Carbon dioxide and hydrogen will be generated under the action of catalyst methanol 、 carbon monoxide and methane The chemical reaction equation of several reactions is:

；

。^[30-31]

2-4. Electrochemical reduction

The electrochemical reduction of carbon dioxide is a process that uses electric energy to reduce carbon dioxide at the cathode of the electrolytic cell and oxidize hydroxyl ions at the anode of the electrolytic cell to oxygen activation energy High, this process can only be realized after a certain high voltage is applied, and the degree of hydrogen precipitation reaction at the cathode increases with the increase of voltage, which will inhibit the reduction of carbon dioxide. Therefore, efficient reduction of carbon dioxide requires appropriate catalysts, so that the electrochemical reduction of carbon dioxide is often an electro catalytic reduction process. The simple mechanism of this process is: in the initial stage, carbon dioxide is adsorbed on the surface of the cathode catalyst to form intermediate products (reaction formula ①); Then the electrons are transferred under the effect of the potential difference between the two electrodes. The transfer number may be 2, 4, 6, 8, 12. The reduction product may be carbon monoxide , formate formic acid , methane ethane and ethylene And so on (reaction formulas ② - ⑧). As it is in aqueous solution, hydrogen evolution reaction will also occur, thus generating hydrogen (reaction formulas ⑨, ⑩).^[32-33]

①

②

③

④

⑤

⑥

⑦

⑧

⑨

⑩

3. React with peroxide

Carbon dioxide energy and Sodium peroxide （Na two O two ）Reaction formation sodium carbonate （Na two CO three ）And oxygen (O two ）, the corresponding chemical reaction equation is:

。^[29]

4. React with Grignard reagent

Under acidic conditions, carbon dioxide can Grignard reagent stay Anhydrous ether Intermediate reaction generation carboxylic acid , the corresponding chemical reaction equation is:

Note: In the formula, R represents aliphatic hydrocarbon group or aromatic hydrocarbon group, and X represents halogen.^[34]

5. Insertion reaction with epoxy compound

Carbon dioxide can react with epoxy compound to form cyclic carbonate under electro catalysis,^[35] The corresponding chemical reaction equation is:

Chemical reaction equation of insertion reaction of carbon dioxide and epoxy compound

6. Preparation of diamond (replacement reaction)

At 440 ℃ (713.15K) and 800 atmospheres (about 80MPa), carbon dioxide can react with metal sodium to form diamond , the corresponding chemical reaction equation is:

。^[36]

7. Dark reaction of photosynthesis (carbon reaction)

Carbon dioxide is involved in photosynthesis Dark reaction (New name: "carbon reaction"^[58] ）Is a green plant photosynthesis The reaction process involved by indispensable raw materials is called "fixation of carbon dioxide", and the corresponding chemical reaction equation is:

。

Note: C in the equation five by Ribulose 1,5-diphosphate （RuPB^[59] ），2C three Is 2 molecules 3-phosphoglycerate 。^[37]

Generation pathway

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Schematic diagram of carbon cycle

Carbon dioxide gas is a part of the atmosphere (0.03% - 0.04% of the total volume of the atmosphere). It is abundant in nature, and its production ways are mainly as follows: ① Organic matter (including animals and plants) can release carbon dioxide in the process of decomposition, fermentation, decay and deterioration. ② During the combustion of oil, paraffin, coal and natural gas, carbon dioxide will also be released. ③ During the production of chemical products, oil and coal will also release carbon dioxide. ④ All feces and humic acid can also release carbon dioxide during fermentation and maturation. ⑤ All animals breathe oxygen and exhale carbon dioxide.^[38]

Preparation method

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Industrial preparation

Calcination method

The carbon dioxide gas generated in the process of calcining limestone (or dolomite) at high temperature is washed, impurities removed and compressed to produce gas carbon dioxide:

。^[2]

Fermentation gas recovery method

The carbon dioxide gas produced during ethanol fermentation is washed, removed and compressed to produce carbon dioxide gas.^[2]

By product gas recovery method

During the production of ammonia, hydrogen and synthetic ammonia, there is often a process of decarbonization (that is, removing carbon dioxide from the gas mixture), so that carbon dioxide in the mixed gas can be absorbed under pressure, heated and desorbed under reduced pressure to obtain high-purity carbon dioxide gas.^[2]

Adsorption expansion method

Generally, the by-product carbon dioxide is used as the feed gas to extract high-purity carbon dioxide from the adsorption phase by adsorption expansion method, and the product is collected by a cryogenic pump; It can also be made by the adsorption distillation method, which uses silica gel, 3A molecular sieve and activated carbon as adsorbent to remove some impurities. After rectification, high-purity carbon dioxide products can be made.^[2]

Carbon kiln process

Carbon dioxide is obtained by refining the gas from the carbon kiln gas and methanol cracking.^[2]

Laboratory preparation

Preparation of marble by reaction with dilute hydrochloric acid

Pithy formula

Laboratory preparation of carbon dioxide, marble and dilute hydrochloric acid. Neither type of soda is used, so it is difficult to control the speed too fast.

Without sulfuric acid instead of hydrochloric acid, magnesium salt is not as cheap as calcium salt. Nitric acid is easy to decompose in the presence of light, and it will not burn when the bottle is full.^[39]

Reactive products

Marble or limestone (mainly CaCO ₃ ）And dilute hydrochloric acid. (Laboratory made carbon dioxide, marble and dilute hydrochloric acid ）^[39-40]

Reaction principle

Reaction equation:

。

Preparation device

Carbon dioxide production unit^[41]

Solid liquid normal temperature type (as shown in the figure).^[40]

Collection method

Since carbon dioxide is denser than air, soluble in water and can react with water, the upward exhaust air method is adopted.^[41]

Inspection method

Put the generated gas into the clarified lime water, and the lime water becomes turbid, which proves that the gas is carbon dioxide.^[41]

Method of verification

If the flame is extinguished, it is proved that the gas has been fully collected.^[40]

matters needing attention

① Possible volatilization during reaction Hydrogen chloride (HCl) gas, which can pass through saturated sodium bicarbonate (NaHCO three ）The solution removes hydrogen chloride gas from the generated gas.^[41]

② If necessary, the water vapor in the generated gas can be removed with a washing cylinder filled with concentrated sulfuric acid.^[41]

③ Calcium carbonate and Concentrated hydrochloric acid Reaction, reason: concentrated hydrochloric acid is easy to volatilize a large amount of hydrogen chloride gas, so that sodium bicarbonate cannot be completely removed, and the purity of carbon dioxide produced will decline.^[39]

④ In the laboratory, marble (CaCO three ）And dilute hydrochloric acid to produce carbon dioxide.^[39]

⑤ Can't use Na two CO three (Soda) and NaHCO three (baking soda) instead of CaCO three Reaction with hydrochloric acid to produce carbon dioxide, reason: Na two CO three And NaHCO three The reaction speed with hydrochloric acid is too fast, and the carbon dioxide generated will escape quickly, which is difficult to control and operate. (Neither type of soda is used, and the speed is too fast to control)^[39]

⑥ Dilute sulfuric acid cannot be used instead of hydrochloric acid, because dilute sulfuric acid and marble (CaCO three ）The reaction will generate calcium sulfate (CaSO) slightly dissolved in water four ）The precipitation covers the surface of marble, hindering the continuous reaction and making the reaction very slow. (No sulfuric acid instead of hydrochloric acid ）^[39]

⑦ MgCO cannot be used three (Magnesium salt) instead of CaCO three (calcium salt), reason: although MgCO three With hydrochloric acid and CaCO three Similar to hydrochloric acid reaction, but due to MgCO three Less than CaCO three Cheap and easy to get. (Magnesium salt is not as cheap as calcium salt)^[39]

⑧ Nitric acid cannot be used instead of hydrochloric acid. The reason is that nitric acid is easy to decompose when exposed to light（

）If nitric acid is used instead of hydrochloric acid, the CO produced two There will be a small amount of NO two And O two 。 In addition, the price of nitric acid is higher than that of hydrochloric acid, so nitric acid is usually not used to replace hydrochloric acid. (Nitric acid decomposes easily when exposed to light)^[39]

⑨ Since carbon dioxide can extinguish the fire, the burning match can be placed at the gas collector mouth for inspection. If the flame is extinguished, it indicates that carbon dioxide has filled the gas collector. (Unable to burn after checking the match)^[39]

Heat to decompose sodium bicarbonate to produce

Put sodium bicarbonate into hard glass tube after it is fully dried, fill glass wool at the nozzle and seal it, and then use an air pump to vacuumize. Then, heat to decompose sodium bicarbonate. The initial carbon dioxide can be released. The gas generated from decomposition needs to be introduced into the ice cooled pipe to condense the water vapor in the gas, and then the gas is successively introduced into the U-shaped pipe filled with calcium chloride and phosphorus pentoxide to dry. The decomposition pressure of sodium bicarbonate is 97.458kPa at 100 ℃ and 166.652kPa at 120 ℃.^[2]

Other methods

baking soda (The main component is sodium bicarbonate) when mixed with white vinegar, a double decomposition reaction occurs to release carbon dioxide gas, and the corresponding chemical reaction equation is:

。^[42]

Main applications

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High purity carbon dioxide is mainly used for electronics industry The calibration gas for medical research and clinical diagnosis, carbon dioxide lasers, detection instruments and other special mixtures are used as regulators in polyethylene polymerization.^[8]

Solid carbon dioxide is widely used to refrigerate dairy products, meat, frozen food and other perishable food in transit, and as a refrigerant in many industrial processes, such as crushing thermosensitive materials, rubber polishing, metal cold treatment, shrink assembly of mechanical parts, vacuum cold trap, etc.^[8]

Gaseous carbon dioxide is used for carbonizing soft drinks, pH control of water treatment process, chemical processing, food preservation, inert protection in chemical and food processing, welding gas, plant growth stimulant, hardening mold and core in casting and pneumatic devices, It is also used as a diluent of bactericidal gas (that is, the mixture of ethylene oxide and carbon dioxide is used as a bactericidal, insecticide, and fumigant, which is widely used for sterilization of medical appliances, packaging materials, clothing, furs, bedding, etc., bone powder disinfection, and fumigation of warehouses, factories, cultural relics, and books).^[8]

Liquid carbon dioxide can be used as refrigerant, low temperature test of aircraft, missiles and electronic components to improve oil well recovery, rubber polishing and control chemical reaction, and can also be used as fire extinguishing agent.^[8]

Supercritical carbon dioxide can be used as solvent to dissolve non-polar, non-ionic and low molecular weight compounds, so it is widely used in homogeneous reactions.^[2]

Pharmacopoeia information

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essential information

This product contains CO two Not less than 99.5% (mL/mL).

character

This product is colorless gas, odorless, and the aqueous solution shows weak acid reaction.

The product can be dissolved in about 1 volume of water at 20 ℃ under normal pressure.

identify

1. Take this product and put it into the barium hydroxide test solution to form a white precipitate, which can be dissolved in acetic acid and bubble boiling.

2. This product can extinguish the flame.

3. The infrared absorption spectrum of this product should be consistent with the control spectrum (Figure 1) (general rule 0402).

inspect

acidity

Take 100mL of water, add 0.2mL of methyl orange indicator solution, mix well, take 50mL of each, put them into two colorimetric tubes A and B, put 1.0mL of hydrochloric acid titrant (0.01mol/L) into tube B, shake well, put it into tube A, and after 1000mL of this product is poured into tube A (the speed is 4000mL per hour), the red color should not be deeper than that of tube B.

water content

Take this product and put it into the dew point analyzer for determination. The moisture content shall not exceed 67 parts per million.

carbon monoxide

Take this product and measure it with a carbon monoxide detection tube. The carbon monoxide content should not exceed 5 parts per million.

sulfur dioxide

Take this product and measure it with a sulfur dioxide detection tube. The sulfur dioxide content should not exceed 2 parts per million.

phosphine

Take this product and measure it with a phosphine detection tube. The phosphine content shall not exceed 3 parts per million.

hydrogen sulfide

Take this product and measure it with hydrogen sulfide detection tube. The hydrogen sulfide content shall not exceed one millionth.

ammonia

Take this product and measure it with ammonia detection tube. The ammonia content shall not exceed 25 parts per million.

hydrocarbon

Determine according to gas chromatography (general rule 0521).

Test sample gas: Take this sample.

Reference gas: Take the gas with methane content of 0.0020% (with nitrogen as diluent).

Chromatographic conditions: a chromatographic column (4mm × 0.8m, 80 mesh) with glass ball as the filler, the column temperature is 110 ℃, the sample inlet temperature is 110 ℃, and the detector is a flame ionization detector, the temperature is 120 ℃.

Determination method: Precisely measure the test gas and the reference gas, respectively inject them into the gas chromatograph, and the peak area measured at the purification temperature of 360 ℃ is the corresponding blank value; Accurately measure the test gas and the reference gas, respectively inject them into the gas chromatograph, determine the peak area, and subtract the corresponding blank value from the peak area to determine the corrected peak area.

Limit: calculated by the external standard method based on the corrected peak area, the hydrocarbon content (calculated by methane) shall not exceed 0.0020%.

Assay

According to the method under oxygen, except for using the absorber as shown in the figure, 125mL of potassium hydroxide solution (0 → 2) instead of copper wire and ammonia ammonium chloride solution is used as the absorption solution, and acidified water (acidic to methyl orange indicator solution) instead of saturated sodium chloride solution is injected into the balance bottle J, operate according to the law until the volume of the remaining gas is constant. Read the liquid level scale in the measuring tube and calculate the content of the test article.

Before inspection and measurement, the test sample cylinder shall be placed at the laboratory temperature for more than 6 hours.

Storage

Store in a pressure cylinder.^[62]

Safety measures

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Natural environment

Environmental hazards

crude greenhouse effect : Greenhouse gases such as carbon dioxide in the atmosphere can radiate longer wavelength longwave radiation to the ground after strongly absorbing the ground longwave radiation, which plays a role in heat preservation of the ground.^[4]

Enhanced greenhouse effect: Since the industrial revolution, human activities have emitted a large amount of carbon dioxide and other greenhouse gases, making the concentration of greenhouse gases in the atmosphere rise sharply, resulting in the growing greenhouse effect.^[43] According to statistics, before industrialization, the global average annual atmospheric carbon dioxide concentration was 278ppm (1 ppm is one millionth), while in 2012, the global average annual atmospheric carbon dioxide concentration was 393.1ppm. By April 2014, the average monthly carbon dioxide concentration in the atmosphere of the northern hemisphere exceeded 400ppm for the first time.^[44]

Global warming cartoon

Global warming: The increasing atmospheric greenhouse effect leads to global warming, resulting in a series of scientific unpredictable global climate problems. According to the international climate change economics report, if human beings maintain their current lifestyle, the global average temperature will rise by 4 ℃ in 50% by 2100. If the global temperature rises by 4 ℃, the glaciers in the north and south poles of the earth will melt, and the sea level will rise accordingly. More than 40 island countries and the most populous coastal cities in the world will be in danger of flooding, and the lives of tens of millions of people in the world will face crisis, even global ecological balance disorder, which will eventually lead to large-scale migration and conflict in the world.^[43]

Countermeasures

Low carbon life : Try to reduce the energy consumed in daily life, so as to reduce carbon dioxide emissions, reduce air pollution and slow down ecological deterioration.^[45]

CCS technology Carbon Dioxide Capture and Storage (CCS) technology is one of the most important technologies to deal with global climate change in the short term. It refers to the separation of carbon dioxide produced by industry and related energy industries through carbon capture technology, and then through storage means, It shall be transported and sealed to the seabed or underground and other places isolated from the atmosphere.^[46]

International law: at the United Nations Conference on Environment and Development held in Brazil in June 1992, 153 countries signed《 United Nations Framework Convention on Climate Change 》The Convention has been in force since March 1994 and has 176 contracting parties (as of February 2015);^[47] In December 1997, the meeting attended by the participants of the United Nations Framework Convention on Climate Change was held in Kyoto, Japan《 Kyoto Protocol 》As a supplementary provision to the United Nations Framework Convention on Climate Change, this treaty has been in force since February 16, 2005 and has 183 parties (as of February 2009);^[48] From November 30 to December 11, 2015, at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change and the 11th Conference of the Parties to the Kyoto Protocol held in Paris, representatives from 195 countries unanimously adopted the Paris Agreement of the United Nations Framework Convention on Climate Change（《 Paris Agreement 》）。^[49]

Human health

Research shows that when the concentration of carbon dioxide in the air is less than 2%, there is no obvious harm to people. If the concentration exceeds this level, it can cause damage to human respiratory organs, that is, carbon dioxide is generally not toxic, but when the concentration of carbon dioxide in the air exceeds a certain limit, it will cause poisoning to the body, and high concentrations of carbon dioxide will cause suffocation. Animal experiments have proved that in the air with normal oxygen content (20%), the higher the concentration of carbon dioxide, the higher the mortality of animals. At the same time, the death of animals caused by pure carbon dioxide is more rapid than that caused by hypoxia. In addition, some people believe that under the condition of hypoxia, 8%~10% concentration of carbon dioxide can cause human and animal deaths in a short time.^[6]

Poisoning principle

High concentration carbon dioxide has stimulating and anesthetic effects and can cause hypoxia and asphyxia in the body.^[6]

Poisoning symptoms

Mild: dizziness, headache, muscle weakness, general malaise, etc.

Moderate: dizziness will lead to falling to the ground; Chest tightness, pain in nose and throat, shortness of breath, chest compression and suffocation; Severe headache, tinnitus, muscle weakness, red skin, high blood pressure, fast and strong pulse.

Severe: sudden dizziness and falling to the ground, suffocation, dyspnea, palpitations, confusion, coma, blue skin, lips and nails, decreased blood pressure, weak pulse, and dilated pupils. The light reflex disappears, the whole body becomes soft, the glottis expands, and one after another stops breathing and heartbeat, leading to death. After the acute phase, some may have symptoms such as lethargy and memory loss.^[6]

First aid measures

① Get the poisoned person out of the environment with high concentration of carbon dioxide quickly, go to a place with fresh air, loosen the collar of the poisoned person, artificially assist breathing to make him inhale oxygen as soon as possible, treat him with hyperbaric oxygen if necessary, and rescue personnel should wear effective respiratory protective devices.

② Inject respiratory stimulants, and give antibiotics if there is secondary infection; Sodium bicarbonate or sodium lactate should be given intravenously when the carbon dioxide binding force decreases; Limb spasmolysis can take a larger dose of sedatives; Sedative drugs can be used for long-term hyperthermia and convulsion; Other treatments such as pulmonary edema, brain edema, etc.^[6]

Preventive methods

Before entering the work area with high concentration of carbon dioxide, check whether the concentration of carbon dioxide in the air exceeds 2%. If it does, effective safety measures should be taken, such as: ① ventilation and detoxification, replacing the air in the workplace, so that the concentration of carbon dioxide in the air does not exceed 2%; ② Wear air supply helmet, self-priming catheter gas mask, oxygen respirator and other commonly used gas masks.^[6]

Precautions for storage

Carbon dioxide is suitable for storage in a cool, ventilated warehouse dedicated to non combustible gases, and is suitable for shipment in liquid or solid form. Pay attention to the following points when storing and transporting carbon dioxide: ① Keep away from kindling and heat sources, and the temperature of the warehouse should not exceed 30 ℃; ② Store separately from inflammable (combustible) materials and avoid mixed storage; ③ The storage area shall be equipped with leakage emergency treatment equipment.^[2]^[8]

Relevant regulations

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In China, carbon dioxide is the 90th substance in the Occupational Exposure Limits for Hazardous Agents in the Workplace Part 1: Chemical Hazardous Agents (GBZ 2.1-2007) issued on April 12, 2007 and implemented on November 1, 2007. In terms of health requirements, the allowable concentration time weighted average (PC-TWA) in the workplace is 9000mg/m three The allowable concentration Short Term Exposure Limit (PC-STEL) is 18000mg/m three 。^[50] In addition, the national regulation closely related to carbon dioxide is the national standard Determination Method of Carbon Dioxide in the Air of Public Places (GB/T 18204.24-2000), which stipulates the determination method of carbon dioxide concentration in the air of public places^[51] This standard has been issued on September 3, 2014 and implemented on December 1, 2014 in the Hygienic Inspection Methods for Public Places Part 2: Chemical pollutants 》(GB/T 18204.2-2014).^[52] For the detection of carbon dioxide, there are three standard detection methods recommended in the Hygienic Inspection Methods for Public Places Part 2: Chemical Pollutants, namely, non dispersive infrared gas analysis (the minimum detection concentration is 0.01%), gas chromatography (the minimum detection concentration is 0.014%), and volumetric titration (the minimum detection concentration is 0.001%).^[53]

In the United States, the threshold concentration of the American Conference of Governmental Industrial Hygienists (ACGIH), the allowable concentration values of the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health, NIOSH) recommended concentration value is 5000ppm (5000 × 10 -6 ）。^[54]

Emissions

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The 2023 government work report points out that in the past five years, carbon dioxide emissions have decreased by 14.1% %^[63] 。

The carbon dioxide emitted by the cement industry accounts for about 8% of the global total carbon emissions from human activities.^[66]

As of June 2023, In the past 10 years, global greenhouse gas emissions have reached a "record high", with an annual emissions of 54 billion tons of carbon dioxide, leading to global warming at an unprecedented rate 。^[67]

On March 19, 2024, the World Meteorological Organization (WMO) released the 2023 Global Climate Report. Data shows that in 2023, the carbon dioxide concentration will continue to rise from the record level in 2022, of which the carbon dioxide concentration level is 50% higher than the pre industrial level.^[69]

Utilize technology

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On April 13, 2023, the 742nd symposium of Xiangshan Scientific Conference Convene, Experts pointed out that carbon dioxide utilization technology has great potential. For example, one ton of methanol synthesized with carbon dioxide can consume about 1.4 tons of carbon dioxide, and can reduce another 4 tons of carbon dioxide emissions by replacing coal with renewable energy.

As of February 2023, there are 57 carbon dioxide utilization technology demonstration projects that have been put into operation and under planning in China, and the number of projects that efficiently convert carbon dioxide into valuable chemical and biological products is about 40%.^[64] The technology developed by the Institute of Thermal Process Engineering of the Karlsruhe Institute of Technology (KIT) can directly extract carbon dioxide from the atmosphere and convert it into carbon black 。^[65]

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