Employees of the Research Laboratory “Perspective Carbon Nanomaterials” of the Chemical Institute named after AM Butlerov of Kazan Federal University have created an efficient and inexpensive nickel-based catalyst for the conversion of toxic 4-nitrophenol to 4-aminophenol.
“Paranitrophenol (4-nitrophenol) is either a reagent or a by-product in many organic synthesis reactions. It poses a serious environmental hazard. Paranitrophenol is usually converted into a much less toxic substance – paraaminophenol (4-aminophenol), which is often used in organic synthesis in the production of dyes and reducing agents, ”explained the head of the laboratory, Ayrat Dimiev.
Most of the catalysts needed for this reaction, according to the scientist, are based on precious metals such as platinum or palladium, so they are very expensive. The scientific community is now actively looking for cheap, but no less effective alternatives.
“Nickel has always been considered as a potential substitute for these precious metals in a number of reduction and hydrogenation reactions,” continues Ayrat Dimiev. “Usually, precious metals are replaced in the catalyst by 30-40% cheaper metal, and we have replaced them completely. The catalyst we have developed on the basis of nickel is several times cheaper than the traditional catalyst based on the use of precious metals ”.
But not only this allowed scientists to reduce the cost of the created catalyst.
“We have taken a new approach to catalyst synthesis. It allowed us to reduce the size of metal particles to an atomic scale, thus significantly increasing the concentration of active centers on the surface of the graphene substrate at the same metal content. Here we first came into contact with the recently actively developed field of single-atom catalysis – catalysis by single atoms, ”said Dimiev.
Each particle (atom) of a new generation catalyst created in KFU works as a separate catalyst, while in conventional catalysts consisting of metal nanoparticles, only atoms on the nanoparticle surface react in the reaction. This leads to an additional rise in the cost of the catalyst.
“The graphene oxide we used as a substrate played an important role in our development. This substance has a two-dimensional layered structure, which is evenly covered with oxygen-containing functional groups, says the first author of the article, a fifth-year student at the Chemistry Institute. AM Butlerova KFU Anna Svalova. “It is these oxygen groups of graphene oxide that we used to bind nickel and keep it on the surface at the atomic level in order to prevent the formation of larger metal nanoparticles”.
The catalyst has demonstrated its efficiency in the reduction of 4-nitrophenol to 4-aminophenol, and the KFU scientists were the first to show that this reaction can take place in a flow reactor, and not only in a flask.
The researchers are confident that the catalyst will work effectively in many reduction and hydrogenation reactions. The plans of the laboratory staff are to test it in the reactions taking place in hydrogen fuel cells.
Used materials from the article “Individual Ni Atoms on Reduced Graphene Oxide as Efficient Catalytic System for Reduction of 4-Nitrophenol”; Anna Svalova, Vasiliy Brusko, Elza Sultanova, Maria Kirsanova, Timur Khamidullin, Iskander Vakhitov, Ayrat M. Dimiev; Applied Surface Science Magazine, August 2021