Researchers at the Korea Institute of Energy Research (KIER) have developed a new technology to decompose R134a refrigerant using industrial waste.
The technology has several potential environmental advantages: It would reduce greenhouse gas emissions, utilize a toxic industrial byproduct and be more energy efficient than existing HFC destruction methods.
At the KIER Hydrogen Composites Laboratory, Dr. Lee Shin-geun's research team successfully decomposed HFC R134a with 99% efficiency by using "red mud" as a catalyst.
Industrial waste red mud raw materials (left) Red mud catalyst made into pellets (right)
Red mud is a byproduct of aluminum production, containing iron, aluminum and silicon oxides, and is red in color. More than 200,000 tons are produced each year. Currently, most red mud is disposed of by landfill, but it is highly alkaline and contains heavy metals, which can pollute soil and water.
Traditionally, R134a is mainly treated by combustion and plasma methods, but combustion produces secondary pollution, while plasma methods require high temperatures, consume a lot of energy and increase equipment costs. To address these problems, the research team developed a catalytic decomposition technology that can operate at lower temperatures than plasma. They found that metal components such as iron and aluminum in red mud can interact with each other to form a powerful and stable refrigerant decomposition catalyst.
Red mud has a porous structure, a large surface area per unit mass and high thermal stability, which enables the reaction materials to flow efficiently and prevents physical and chemical deformation and damage to the catalyst. In addition, red mud can also serve as a support to provide an environment conducive to catalytic reactions and enhance the durability and activity of the catalyst.
In order to further enhance the decomposition effect, the research team used a simple heat treatment process to promote the interaction of calcium, silicon and aluminum components to form a composite material of tricalcium aluminate and calcium aluminum feldspar. This material is usually used to improve the strength of cement. It can enhance the binding force of catalyst particles and expand the reaction area, thereby improving the decomposition effect.
The hydrogen fluoride produced during the decomposition of R134a reacts with calcium oxide to form calcium fluoride. This chemically stable calcium fluoride forms a thin film on the catalyst surface, protecting the catalyst and preventing it from failing.
The catalyst developed by the research team maintained a high decomposition rate of more than 99% for 100 hours, showing excellent decomposition performance. Through a simple drying and crushing process, 1 kg of catalyst can be produced per hour, which is convenient for large-scale production.
Since the raw materials are recycled industrial waste, there is no cost, which can reduce waste disposal costs and create additional income.
Dr. Li Xingen said: "Red mud is a strong alkaline substance that will cause serious pollution when released into the environment, but there has been no suitable treatment and recycling technology. The catalyst manufacturing technology we developed can not only recycle waste and reduce environmental pollution, but also efficiently decompose refrigerants with a strong greenhouse effect."
