Does carbon dioxide burn? Carbon dioxide: properties, production, application

Carbon monoxide (CO) is a colourless, very light gas (lighter than air) and odorless. But the "smell of carbon monoxide" is felt due to impurities organic elements in fuel. Carbon monoxide at home appears every time when wood is burned. The main cause of carbon monoxide is the lack of oxygen in the combustion area.

The occurrence of intoxication

Carbon monoxide at home occurs when carbon is burned due to a lack of oxygen. Combustion in furnaces of fuel occurs in several stages:

1. First, the carbon burns, releasing carbon dioxide CO2;
2. The carbon dioxide then comes into contact with the red-hot residue of coke or coal, creating carbon monoxide;
3. Then, the carbon monoxide burns (blue flame) to form carbon dioxide, which escapes through the chimney.

Without draft in the furnace (the chimney is clogged, there is no supply air for combustion, the damper is closed prematurely), the coals continue to smolder without a weak supply of oxygen, so carbon monoxide does not burn and can be dispersed throughout the heated room, causing toxic effect on the body and poisoning (waste).

Factors of fumes poisoning

Carbon monoxide poisonous gas is odorless and colorless, making it very dangerous. Causes of carbon monoxide poisoning can be:

• Faulty operation of the fireplace stove and chimney (clogged chimney, cracks in the stove).
• Violation (closing of the furnace damper untimely, poor draft, insufficient access to the firebox of fresh air).
• The presence of a person in the very heart of the fire.
• Maintenance of a car in a room with low ventilation.
• The use of low-quality air in breathing apparatus and scuba gear.
• Sleeping in a car with the engine running.
• Using a grill with low ventilation.

Signals and signs of poisoning

At a low concentration of gas, the first signs of toxic effects and poisoning may form: lacrimation, dizziness and pain, nausea and weakness, confusion, dry cough, there are auditory and visual hallucinations. Feeling the symptoms of poisoning, you need to get out into fresh air as soon as possible.

With a long period of time spent in a room with a low density of carbon monoxide, symptoms of poisoning occur: tachycardia, respiratory failure, impaired coordination, drowsiness, visual hallucinations, blue skin of the face and mucous membranes, vomiting, loss of consciousness, there may be convulsions.

With increased concentration - there is a loss of consciousness and coma with convulsions. Without first medical care, the victim may die from carbon monoxide poisoning.

The impact of carbon monoxide in the home on the human body

Carbon monoxide enters through the lungs, contacts hemoglobin in the blood and prevents the transfer of oxygen to organs and tissues. From oxygen starvation, the nervous system and brain function are disturbed. The higher the concentration of carbon monoxide and longer period being in the room, the stronger the poisoning and the greater the likelihood of death.

After poisoning, medical supervision is necessary for several days, since complications are often observed. Severely poisoned victims should be hospitalized. Problems with nervous system and lungs are possible even weeks after the incident. Curiously, women are less affected by carbon monoxide than men.

Carbon monoxide detector for home

Poisoning or fumes can be prevented by using a stand-alone carbon monoxide alarm or sensor. If the amount of carbon monoxide in a residential or technical room exceeds the permissible level, the sensor will signal, warning of the threat. Carbon monoxide detectors are electrochemical sensors designed to continuously monitor the level of CO in a room and respond with light and sound signals to high level concentration of carbon monoxide in the air.

When you decide to buy a carbon monoxide detector for your home, pay attention to the features (with external similarity) of the devices: an open fire detector and a smoke alarm, a carbon monoxide and carbon dioxide detector reacts to different elements in the air of the room. Carbon monoxide sensors for the home are installed at a height of one and a half meters from the floor (some recommend placing 15-20 cm from the ceiling). The carbon dioxide detector is placed near the instrument panel or at floor level (carbon dioxide is much heavier than air), and the smoke detector should be on the ceiling.

In many countries, the use of the above sensors is a mandatory condition provided by law to ensure the safety and health of the population. In Europe, only a smoke detector is required. With us, the installation of a carbon monoxide sensor is still a voluntary matter. Such sensors are generally an inexpensive device, so it is better not to risk your life and buy a carbon monoxide alarm for your home.

How to avoid carbon monoxide poisoning in the house

By following safety rules, carbon monoxide poisoning can be prevented:

— Do not use appliances that burn fuel without sufficient skills, knowledge and tools.

- Do not burn charcoal in a poorly ventilated room.

- Make sure that the stove, exhaust and supply ventilation and chimney are working properly.

- On the smoke channels of wood-burning stoves, it is necessary to provide for the installation of 2 tight valves in series, and on the channels of stoves operating on coal or peat, only one valve with a hole of 15 mm.

- Do not leave a car with a running engine in the garage.

Sensors that indicate an increase in carbon monoxide concentration can provide additional protection against poisoning, but they should not replace other preventive measures.

Carbon monoxide in stove heating

A fireplace or stove with a closed valve and the remains of unburned fuel is a source of carbon monoxide and an invisible poisoner. Assuming that the fuel has completely burned out, the owners of the stoves close the chimney damper to keep the heat. Smoldering embers with a lack of air create carbon monoxide, which penetrates into the room through leaky zones of the furnace system.

Also in the chimney, with weak draft and no air supply, chemical underburning of the fuel occurs, and as a result, the appearance and accumulation of carbon monoxide at home.

, carbon dioxide , properties of carbon dioxide , production of carbon dioxide

It is not suitable for life support. However, plants “feed” on it, turning it into organic matter. In addition, it is a kind of "blanket" of the Earth. If this gas suddenly disappears from the atmosphere, the Earth will become much cooler, and the rains will practically disappear.

"Blanket of the Earth"

(carbon dioxide, carbon dioxide, CO 2) is formed by combining two elements: carbon and oxygen. It is formed during the combustion of coal or hydrocarbon compounds, during the fermentation of liquids, and also as a product of the respiration of people and animals. In small quantities, it is also found in the atmosphere, from where it is assimilated by plants, which, in turn, produce oxygen.

Carbon dioxide colorless and heavier than air. Freezes at −78.5°C to form snow composed of carbon dioxide. In the form of an aqueous solution, it forms carbonic acid, however, it does not have sufficient stability to be easily insulated.

Carbon dioxide is the "blanket" of the Earth. It easily transmits ultraviolet rays that heat our planet, and reflects infrared rays emitted from its surface into space. And if suddenly carbon dioxide disappears from the atmosphere, it will primarily affect the climate. It will become much cooler on Earth, it will rain very rarely. What this will eventually lead to is not difficult to guess.

True, such a catastrophe does not yet threaten us. Rather, on the contrary. Burning organic matter: oil, coal, natural gas, wood - gradually increases the carbon dioxide content in the atmosphere. This means that over time it is necessary to wait for a significant warming and moistening of the earth's climate. By the way, the old-timers believe that it is already noticeably warmer than it was during their youth...

Carbon dioxide is released liquid low temperature, liquid high pressure and gaseous. It is obtained from waste gases from the production of ammonia, alcohols, as well as on the basis of special fuel combustion and other industries. Gaseous carbon dioxide is a colorless and odorless gas at a temperature of 20 ° C and a pressure of 101.3 kPa (760 mm Hg), density - 1.839 kg / m 3. Liquid carbon dioxide is simply a colorless, odorless liquid.

Non-toxic and non-explosive. At concentrations above 5% (92 g/m 3 ), carbon dioxide has a harmful effect on human health - it is heavier than air and can accumulate in poorly ventilated rooms near the floor. This reduces the volume fraction of oxygen in the air, which can cause the phenomenon of oxygen deficiency and suffocation.

Getting carbon dioxide

In industry, carbon dioxide is produced from furnace gases, from decomposition products of natural carbonates(limestone, dolomite). The mixture of gases is washed with a solution of potassium carbonate, which absorbs carbon dioxide, turning into hydrogen carbonate. Hydrocarbonate solution decomposes when heated, releasing carbon dioxide. At industrial production gas is pumped into cylinders.

Under laboratory conditions, small amounts are obtained interaction of carbonates and bicarbonates with acids, such as marble with hydrochloric acid.

"Dry ice" and other beneficial properties of carbon dioxide

Carbon dioxide is widely used in everyday practice. For example, sparkling water with the addition of aromatic essences - a wonderful refreshing drink. AT Food Industry carbon dioxide is also used as a preservative - it is indicated on the packaging under the code E290 and also as a baking powder.

Carbon dioxide fire extinguishers used in fires. Biochemists have found that fertilizer ... air with carbon dioxide very effective way to increase productivity different cultures. Perhaps, such a fertilizer has a single, but significant drawback: it can only be used in greenhouses. Plants producing carbon dioxide liquefied gas packaged in steel cylinders and sent to consumers. If you open the valve, then ... snow bursts out of the hole with a hiss. What a miracle

Everything is explained simply. The work expended on compressing the gas is much less than that required to expand it. And in order to somehow compensate for the resulting deficit, carbon dioxide cools sharply, turning into "dry ice". It is widely used for food preservation and before regular ice has significant advantages: firstly, its “cooling capacity” is twice as high per unit weight; secondly, it evaporates without residue.

Carbon dioxide is used as the active medium in wire welding, since at the temperature of the arc, carbon dioxide decomposes into carbon monoxide CO and oxygen, which, in turn, interacts with the liquid metal, oxidizing it.

Carbon dioxide in canisters is used in air gun and as power source for engines in aeromodelling.

Carbon dioxide is a colorless gas with a barely perceptible odor, non-toxic, heavier than air. Carbon dioxide is widely distributed in nature. It dissolves in water, forming carbonic acid H 2 CO 3, giving it a sour taste. The air contains about 0.03% carbon dioxide. The density is 1.524 times greater than the density of air and is equal to 0.001976 g / cm 3 (at zero temperature and a pressure of 101.3 kPa). Ionization potential 14.3V. Chemical formula– CO2.

In welding production, the term is used "carbon dioxide" cm. . The "Rules for the Design and Safe Operation of Pressure Vessels" adopted the term "carbon dioxide", and in - term "carbon dioxide".

There are many ways to produce carbon dioxide, the main ones are discussed in the article.

The density of carbon dioxide depends on pressure, temperature and state of aggregation in which it is located. At atmospheric pressure and a temperature of -78.5 ° C, carbon dioxide, bypassing liquid state, turns into a white snow-like mass "dry ice".

Under a pressure of 528 kPa and at a temperature of -56.6 ° C, carbon dioxide can be in all three states (the so-called triple point).

Carbon dioxide is thermally stable, dissociates into carbon monoxide and only at temperatures above 2000°C.

Carbon dioxide is first gas to be described as a discrete substance. In the seventeenth century, a Flemish chemist Jan Baptist van Helmont (Jan Baptist van Helmont) noticed that after burning coal in a closed vessel, the mass of ash was much less than the mass of the burned coal. He explained this by the fact that coal is transformed into an invisible mass, which he called "gas".

The properties of carbon dioxide were studied much later in 1750. Scottish physicist Joseph Black (joseph black.

He discovered that limestone (calcium carbonate CaCO 3 ) when heated or reacted with acids, releases a gas, which he called "bound air". It turned out that "bound air" is denser than air and does not support combustion.

CaCO 3 + 2HCl \u003d CO 2 + CaCl 2 + H 2 O

Passing "bound air" i.e. carbon dioxide CO 2 through an aqueous solution of lime Ca (OH) 2 calcium carbonate CaCO 3 is deposited on the bottom. Joseph Black used this experience to prove that carbon dioxide is released as a result of animal respiration.

CaO + H 2 O \u003d Ca (OH) 2

Ca(OH) 2 + CO 2 = CaCO 3 + H 2 O

Liquid carbon dioxide is a colorless, odorless liquid whose density varies greatly with temperature. It exists at room temperature only at a pressure of more than 5.85 MPa. The density of liquid carbon dioxide is 0.771 g/cm 3 (20°C). At temperatures below +11°C it is heavier than water, and above +11°C it is lighter.

The specific gravity of liquid carbon dioxide varies significantly with temperature, so the amount of carbon dioxide is determined and sold by weight. The solubility of water in liquid carbon dioxide in the temperature range of 5.8-22.9°C is not more than 0.05%.

Liquid carbon dioxide turns into a gas when heat is applied to it. Under normal conditions (20°C and 101.3 kPa) when 1 kg of liquid carbon dioxide evaporates, 509 liters of carbon dioxide are formed. With excessively rapid gas extraction, a decrease in pressure in the cylinder and insufficient heat supply, carbon dioxide cools, its evaporation rate decreases, and when the “triple point” is reached, it turns into dry ice, which clogs the hole in the reduction gear, and further gas extraction stops. When heated, dry ice directly turns into carbon dioxide, bypassing the liquid state. Much more heat is required to vaporize dry ice than to vaporize liquid carbon dioxide - so if dry ice has formed in a cylinder, it evaporates slowly.

Liquid carbon dioxide was first obtained in 1823. Humphrey Davy(Humphry Davy) and Michael Faraday(Michael Faraday).

Solid carbon dioxide "dry ice" appearance reminiscent of snow and ice. The content of carbon dioxide obtained from dry ice briquettes is high - 99.93-99.99%. Moisture content in the range of 0.06-0.13%. Dry ice, being in the open air, evaporates intensively, therefore, containers are used for its storage and transportation. Carbon dioxide is produced from dry ice in special evaporators. Solid carbon dioxide (dry ice) supplied in accordance with GOST 12162.

Carbon dioxide is the most commonly used:

• to create a protective environment for metals;
• in the production of carbonated drinks;
• cooling, freezing and food storage;
• for fire extinguishing systems;
• for cleaning surfaces with dry ice.

The density of carbon dioxide is quite high, which makes it possible to protect the reaction space of the arc from contact with air gases and prevents nitriding at relatively low carbon dioxide flow rates in the jet. Carbon dioxide is, during the welding process, it interacts with the weld metal and has an oxidizing and carburizing effect on the metal of the weld pool.

Previously an obstacle to the use of carbon dioxide as a protective medium were at the seams. The pores were caused by boiling of the hardening metal of the weld pool from the release of carbon monoxide (CO) due to its insufficient deoxidation.

At high temperatures, carbon dioxide dissociates to form highly active free, monatomic oxygen:

Oxidation of the weld metal released during welding from carbon dioxide free is neutralized by the content of an additional amount of alloying elements with a high affinity for oxygen, most often silicon and manganese (in excess of the amount required to alloy the weld metal) or fluxes introduced into the welding zone (welding).

Both carbon dioxide and carbon monoxide are practically insoluble in solid and molten metal. Free active oxidizes the elements present in the weld pool, depending on their affinity for oxygen and concentration according to the equation:

Me + O = MeO

where Me is a metal (manganese, aluminum, etc.).

In addition, carbon dioxide itself reacts with these elements.

As a result of these reactions, when welding in carbon dioxide, a significant burnout of aluminum, titanium and zirconium is observed, and less intense - silicon, manganese, chromium, vanadium, etc.

The oxidation of impurities occurs especially vigorously at . This is due to the fact that when welding with a consumable electrode, the interaction of molten metal with gas occurs when the drop is at the end of the electrode and in the weld pool, and when welding with a non-consumable electrode, only in the bath. As is known, the interaction of gas with metal in the arc gap is much more intense due to high temperature and a larger metal-gas contact surface.

In view of chemical activity carbon dioxide in relation to tungsten, welding in this gas is carried out only with a consumable electrode.

Carbon dioxide is non-toxic and non-explosive. At concentrations above 5% (92 g/m 3 ), carbon dioxide has a harmful effect on human health, as it is heavier than air and can accumulate in poorly ventilated rooms near the floor. This reduces the volume fraction of oxygen in the air, which can cause the phenomenon of oxygen deficiency and suffocation. Premises where welding is carried out using carbon dioxide must be equipped with general-exchange supply and exhaust ventilation. The maximum allowable concentration of carbon dioxide in the air of the working area is 9.2 g/m 3 (0.5%).

Carbon dioxide is supplied by . To obtain high-quality seams, gaseous and liquefied carbon dioxide of the highest and first grades are used.

Carbon dioxide is transported and stored in steel cylinders or large-capacity tanks in a liquid state, followed by gasification at the plant, with a centralized supply of welding stations through ramps. 25 kg of liquid carbon dioxide is poured into a standard one with a water capacity of 40 l, which, at normal pressure, occupies 67.5% of the volume of the cylinder and, upon evaporation, yields 12.5 m 3 of carbon dioxide. Air accumulates in the upper part of the cylinder along with gaseous carbon dioxide. Water, being heavier than liquid carbon dioxide, collects at the bottom of the cylinder.

To reduce the humidity of carbon dioxide, it is recommended to install the cylinder with the valve down and, after settling for 10 ... 15 minutes, carefully open the valve and release moisture from the cylinder. Before welding, it is necessary to release a small amount of gas from a normally installed cylinder in order to remove air trapped in the cylinder. Part of the moisture is retained in carbon dioxide in the form of water vapor, worsening when welding a seam.

When the gas is released from the cylinder, due to the effect of throttling and absorption of heat during the evaporation of liquid carbon dioxide, the gas is significantly cooled. With intensive gas extraction, the reducer can be blocked by frozen moisture contained in carbon dioxide, as well as dry ice. To avoid this, when taking carbon dioxide, a gas heater is installed in front of the reducer. The final removal of moisture after the reducer is carried out with a special desiccant filled with glass wool and calcium chloride, silica helium, copper sulphate or other moisture absorbers.

The carbon dioxide cylinder is painted black, with the inscription in yellow letters "CARBON DIOXIDE".

1.6. COMBUSTION PRODUCTS

Combustion products are gaseous, liquid or solids formed during the combustion process. The composition of combustion products depends on the composition of the burning substance and on the conditions of its combustion. Organic and inorganic combustible substances consist mainly of carbon, oxygen, hydrogen, sulfur, phosphorus and nitrogen. Of these, carbon, hydrogen, sulfur and phosphorus are able to oxidize at the combustion temperature and form combustion products: CO, CO 2 , SO 2 , P 2 O 5 . Nitrogen at the combustion temperature is not oxidized and is released in a free state, and oxygen is consumed for the oxidation of combustible elements of the substance. All of these combustion products (with the exception of carbon monoxide CO) are no longer able to burn in the future. They are formed during complete combustion, that is, during combustion, which proceeds with the access of a sufficient amount of air and at a high temperature.

With incomplete combustion of organic substances under conditions low temperatures and lack of air, more diverse products are formed - carbon monoxide, alcohols, ketones, aldehydes, acids and other complex chemical compounds. They are obtained by partial oxidation of both the fuel itself and the products of its dry distillation (pyrolysis). These products produce acrid and poisonous smoke. In addition, the products of incomplete combustion themselves are capable of burning and forming explosive mixtures with air. Such explosions occur when extinguishing fires in basements, dryers and indoors with large quantity combustible material. Let us briefly consider the properties of the main combustion products.

Carbon dioxide

Carbon dioxide or carbon dioxide (CO 2) is a product of the complete combustion of carbon. Has no smell and color. Its density in relation to air = 1.52. Density of carbon dioxide at temperature T= 0 0 С and at normal pressure R= 760 millimeters of mercury (mm hg ) is equal to 1.96 kg/m 3 (air density under the same conditions is equal to ρ = 1.29 kg/m 3). Carbon dioxide is highly soluble in water (at T\u003d 15 0 C, one liter of gas dissolves in one liter of water). Carbon dioxide does not support combustion of substances, with the exception of alkali and alkaline earth metals. The combustion of magnesium, for example, occurs in an atmosphere of carbon dioxide according to the equation:

CO 2 +2 Mg \u003d C + 2 MgO .

The toxicity of carbon dioxide is negligible. The concentration of carbon dioxide in the air of 1.5% is harmless to humans for a long time. When the concentration of carbon dioxide in the air exceeds 3-4.5%, being indoors and inhaling the gas for half an hour is life-threatening. At a temperature T= 0 0 С and pressure R= 3.6 MPa carbon dioxide passes into a liquid state. The boiling point of liquid carbon dioxide is T= –78 0 C. With the rapid evaporation of liquid carbon dioxide, the gas cools and passes into a solid state. Both in liquid and solid state, drops and powders of carbon dioxide are used to extinguish fires.

carbon monoxide

Carbon monoxide or carbon monoxide (CO) is a product of the incomplete combustion of carbon. This gas is odorless and colorless, therefore it is especially dangerous. Relative density = 0.97. Density of carbon monoxide at T= 0 0 С and R= 760 mm hg is 1.25 kg/m 3 . This gas is lighter than air and accumulates in the upper part of the room during fires. Carbon monoxide is almost insoluble in water. It is capable of burning and forms explosive mixtures with air. Carbon monoxide, when burned, produces a blue flame. Carbon monoxide is highly toxic. Inhalation of air with a carbon monoxide concentration of 0.4% is fatal to humans. Standard gas masks do not protect against carbon monoxide, so special filters or oxygen isolating devices are used in case of fires.

Sulphur dioxide

Sulfur dioxide (SO 2 ) is the combustion product of sulfur and sulfur compounds. A colorless gas with a characteristic pungent odor. Relative density of sulfur dioxide = 2.25. The density of this gas at T= 0 0 С and R= 760 mm hg is 2.9 kg / m 3, that is, it is much heavier than air. Sulfur dioxide is highly soluble in water, for example, at a temperature T\u003d 0 0 C eighty liters are dissolved in one liter of water SO2 , and when T\u003d 20 0 C - forty liters. Sulfur dioxide does not support combustion. It acts irritatingly on the mucous membranes of the respiratory tract, as a result of which it is very toxic.

Smoke

During the combustion of many substances, in addition to the combustion products discussed above, smoke is released - a dispersed system consisting of the smallest solid particles suspended in a gas. The diameter of the smoke particles is 10 -4 -10 -6 cm (from 1 to 0.01 µm). Note that 1 micron (micron) is equal to 10 -6 m or 10 -4 see larger particulate matter, formed during combustion, quickly settle in the form of soot and soot. When burning organic matter, the smoke contains particulate soot suspended in CO 2 , CO , N 2 , SO 2 and other gases. Depending on the composition and combustion conditions of the substance, smokes of different composition and color are obtained. When burning wood, for example, grayish-black smoke is formed, fabrics - brown smoke, oil products - black smoke, phosphorus - white smoke, paper, straw - whitish-yellow smoke.

New catalysts will help turn carbon dioxide into fuel.

To get energy, as a rule, you need to burn something: ordinary cars burn fuel in internal combustion engines, electric cars charge their batteries from electricity supplied, for example, at a thermal power plant that burns natural gas, and even for muscle or mental work we need “burn” the breakfast you eat inside yourself.

Any organic fuel, be it gasoline hydrocarbons or carbohydrates from a chocolate bar, contains carbon atoms, which at the end of their energy path turn into carbon dioxide. Well, the gas, in turn, is sent to the atmosphere, where it can accumulate and cause all sorts of bad effects like global warming.

From an energy point of view, carbon dioxide is absolutely useless, since the carbon in it has completely “burned out”, firmly and inextricably bonding itself to two oxygen atoms. It no longer burns, and the only thing that can be done with it is to drown or bury it. You can drown it by dissolving it in the ocean - and this is really one of the ways to utilize CO 2. Another way is to pump it under high pressure underground, preferably where there are oil fields; this will improve the recovery of oil reservoirs and help to extract more oil. However, chemists still found a way to "cook porridge from an ax" - there is a third way to utilize CO 2 when it is turned into fuel.

To turn CO 2 into fuel, you need to "chemize" with a carbon dioxide molecule, for example, take away one oxygen atom from it. The carbon dioxide will then turn into carbon monoxide CO. Despite the fact that for most carbon monoxide is "the gas from which careless users of wood stoves periodically die", in industry it is used in a variety of processes: firstly, it can be burned and obtained energy, secondly, it can be used in metallurgical processes, and thirdly, various organic molecules, including liquid fuel, can be synthesized from it. It is the last point that opens up petrochemical prospects for carbon dioxide.

However, it should be noted that the use of carbon monoxide in chemical purposes is not something completely new. At the dawn of the twentieth century, German chemists Franz Fischer and Hans Tropsch developed a method for obtaining liquid fuel from ordinary coal: first, synthesis gas is obtained from coal and water - this is the name of a mixture of carbon monoxide and hydrogen, and then using a catalyst from synthesis gas. gas receive various hydrocarbons. This method was in demand when ordinary oil was not enough, but over time, in the second half of the twentieth century, the method of obtaining fuel from coal became simply an expensive alternative to "classical" oil refining technologies. But if in the Fischer-Tropsch process coal is used as a raw material, which in itself is a mineral, then chemists from for the same purpose - obtaining synthesis gas - have developed a method that allows you to make it from "unnecessary" carbon dioxide.

Such things are impossible without the use of catalysts, and in order to get a working catalyst, chemists sometimes have to go to all sorts of tricks. The point is that, apart from a certain chemical composition, for a catalyst its very important internal structure. To put it simply, a catalyst applied to a flat surface may not work, but if it is applied to a porous surface, and if the pores have a certain size, then it will be able to work in full force.

To create such a catalyst, chemists took an electrically conductive material as a substrate and deposited a layer of polystyrene beads about 200 nanometers in diameter on it. After that, the voids remaining in the space between the balls were filled with silver atoms. (As an analogy, we can imagine that we poured a layer of billiard balls on the floor, and then poured everything on top with an even layer of molten paraffin.) Now, to get a porous substrate, you need to somehow remove all the balls from the material, leaving the rest intact. structure. In the case of billiard balls, this would be very problematic, but in the case of polystyrene balls, everything turned out to be much simpler - and as a result, after removing the polystyrene on the electrode surface, a cellular structure of silver with "honeycombs" of a certain size was obtained.

Such a material, as it turned out, well converts carbon dioxide into synthesis gas, and the efficiency and selectivity of the catalyst is controlled by the size of the honeycombs: if you take larger polystyrene balls at the stage of catalyst synthesis, then after the reaction one product composition will be obtained, and if smaller, then another . Detailed research results are published in the journal Angewandte Chemie .

And everything seems to be fine, and humanity should celebrate the victory over greenhouse gas emissions, and every pipe that emits combustion products into the atmosphere should be equipped with a similar silver catalyst, but still it is worth making one remark. One of the important laws by which the world around us lives is the law of conservation: mass and energy do not arise from nowhere and do not disappear into nowhere. This is also true for atoms. chemical elements, and for the heat generated by burning fuel, and for electrical energy. Therefore, how much energy is obtained by burning carbon monoxide to carbon dioxide, at least the same amount of energy needs to be spent (simplified) to turn a carbon dioxide molecule back into a carbon monoxide molecule. And it is obvious that such a generally “green” technology for utilizing greenhouse gas needs its own source of energy, which at least would not “start” into the atmosphere as much CO 2 as could be turned into a useful product.

Where do you get the energy to turn one gas into another? For example, from wind or solar power plants that produce energy, but do not emit fuel combustion products into the atmosphere - as a result, this would reduce the total amount of carbon dioxide.

It's funny that ancient plants and bacteria were engaged in similar activities, absorbing carbon dioxide, which was then in excess in the atmosphere, and converting it into organic substances, which later became fossil fuels. It is possible that in the future humanity will have to do something similar, but only with the use of chemical technologies.