Scientists of St. Petersburg University together with researchers of the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences have developed a type of "pipe in a pipe" reactor that ensures the efficient flow of chemical reactions without the use of external heaters. This approach significantly reduces energy costs during chemical research.
Chemical reactions may be accompanied by the release (exothermic) or absorption (endothermic) of heat. In the first case, the resulting thermal energy is often dissipated, but it can be used to trigger the second type of reactions that require additional heat to absorb it. The design created by chemists, similar to a thermos, allows you to use the released thermal energy of one reaction to start the second.
Scientists from St. Petersburg State University and the N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences have developed a special type of tube-in—tube reactor that provides a more efficient reaction of calcium carbide hydrolysis - the interaction of calcium and carbon compounds with water. Today, calcium carbide is actively used in industry to produce acetylene gas and its use in the production of acetic acid, ethyl alcohol, plastics, rubber and even rocket engines.
The reactor consists of two tubes inserted into each other, the walls of which do not touch, and a connecting part printed on a 3D printer made of nylon. This design made it possible to create a kind of warming thermos — the "heaters" are located in the space between the two tubes, that is, in the "wall" of the reactor.
To carry out an effective reaction, the scientists placed calcium carbide granules in the space between the tubes, added solvent, water and stirred. The mixture was heated, and the heat released passed into the inner part, triggering endothermic reactions between the reagents in it. This made it possible to carry out two types of reactions with lower energy consumption, without the use of external heaters.
The generated and absorbed heat was recorded using a thermal imager — this allowed us to track in real time how the temperature inside the device changes during the reaction. It turned out that the thermal effect obtained in the reactor depends on the type of solvent, as well as on the amount of water and carbide. So, if there was little — only 5% — water and a lot of solvent in the "wall" of the installation, then heat generation was practically not observed. An increase in the amount of water to 50% or more, on the contrary, led to a rapid — in just five minutes — increase in the temperature in the reactor up to 90 ° C.
"Calcium carbide is capable of starting reactions without external heat sources, and the "pipe in a pipe" device developed by us helps to control and, if necessary, change the rate of its hydrolysis. This can be used in industry — for example, in the production of acetylene. When water is added to the carbide, so much heat is obtained that the acetylene released polymerizes and becomes unusable. Using mixtures of solvents with water, it is possible to slow down this process, stop unwanted polymerization and remove heat more efficiently," said Konstantin Rodygin, project manager, researcher at the St. Petersburg State University Laboratory of Cluster Catalysis.
The research was conducted on the basis of the resource centers "Methods of Substance Composition Analysis" and "Magnetic Resonance Research Methods" of the St. Petersburg State University Science Park.
It should be noted that the scientific group of chemists of St. Petersburg State University is also working on a carbon-neutral production cycle strategy that allows reducing carbon dioxide emissions.
The results of the work supported by a grant from the Russian Science Foundation are published in the International Journal of Molecular Science
PHOTO: Hydrolysis of calcium carbide in a test tube with the eyes of a thermal imager © St. Petersburg State University Press Service
Source: St. Petersburg State University Press Service,

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