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The purpose of the study was to synthesise a mixed oxide of nickel and silver for the epoxidation (selective oxidation) of ethylene, one of the most widely produced polymers for the chemical industry. Ethylene oxide is used to create compounds for the production of plastics, textiles and household chemicals. The normal reaction of ethylene production occurs at temperatures of 220 to 300 degrees Celsius and a pressure of 10 to 30 atmospheres, which is comparable to ocean pressures at a depth of 100 to 300 metres.
The scientists from the Institute of Catalysis SB RAS managed to reduce the reaction temperature and pressure down to room temperature and atmospheric pressure. For that purpose, the authors of the study used the aforementioned delafossite material. Initially, delafossite was a designation for a mineral that was discovered in Yekaterinburg in 1873 and named after the mineralogist Gabriel Delafosse. Afterwards, this mineral gave its name to an entire class of structurally similar compounds, one of which was used during the experiment by the Institute of Catalysis SB RAS researchers.
“We discovered oxygen species on the surface of the mixed oxide of silver and nickel that are capable of epoxidising ethylene at room temperature. These species occur in relation to the unusual states of silver and nickel on the surface of oxide particles. It is more expedient to carry out the reaction at room temperature compared to the current industrial process, as you can save on the heating system and high-pressure reactors. The potential for industrial use is definitely there,” Dmitry Svintsitskiy, one of the authors of the study and candidate of chemical sciences, is quoted as saying by the Institute of Catalysis SB RAS.
In the future, the scientists plan to study in more depth the use of compounds with delafossite structure as catalysts. “We will identify patterns and relationships between the structure, the surface state and the catalytic activity traced in mixed oxide systems. We need to know, which centres are active in these catalysts, what affects their properties and how stable they are,” the Institute of Catalysis SB RAS quotes Mr. Svintsitskiy as saying.
