Innovation in Catalytic Converters
Published on : Saturday 30-11-2019
How innovative use of Rajasthani clay improves the performance of catalytic converters for automobiles.
In a significant discovery, a team comprising Prof Rakesh K Sharma and his student Devika Laishram have developed a patented non-rare earth, non-noble metal based catalytic converter using Rajasthani Clay. The catalytic converter is developed by clever use of Iron-Nickel-Cobalt nanoparticles incorporated in Rajasthani clay. The metal oxides work as oxygen reservoir and could completely oxidise NOx, COx, and hydrocarbons at lower than 300°C temperature.
Background
Automobile industry is facing more and stricter emissions regulations in an effort to reduce the amount of harmful air pollutants released into the environment. These are particularly related to NOx, COx, and soot along with particulate matter. Currently, one method of reducing harmful emissions is a three-way catalytic (TWC) converter that reduces harmful NOx to N2 and O2, oxidises CO to CO2, and oxidises residual hydrocarbons to CO2 and water. However, it requires the use of the rare-earth elements Cerium (Ce) and Palladium, which increases the price of the device, besides the materials also facing supply constraints of late. These expensive metals make the catalyst converter one of the costliest part of the car with price ranging from $1000-$1500. Each catalytic converter has about 5-7gm of pure Palladium, which costs around $60 per gram, which makes it more expensive than gold. Despite that cost, the performance of catalytic converter goes down with time, mostly in 8-10 years, while the approved life of a car is about 15 years.
The research team led by Prof Sharma has been working on finding an alternate solution by understanding the catalytic converter deactivation and looking for a cheaper solution for the same. His team has found that with time, Palladium particles spread over Ceria undergo surface oxidation and decompose in smaller particles due to high temperature oxidation process (>320 degrees). So there were three challenges: reduction of temperature, replacement of Palladium and Cerium with non-noble metals, and re-design the converter to prevent metal deactivation. The Fe-Ni-Co cooperative nano-particles were used in the isolated Nanospheres (work as single site catalyst) where Hafnia-Rajasthani clay was used as oxygen reservoir. The catalytic performance was found to be better than conventional converter at <300 degrees. The primary part of work has been published in the reputed American Chemical Society Journal on Hafnia catalysed soot oxidation (ACS Sustainable Chem. Eng. 2018, 6, 9, 11286-11294). The clay/Hafnia has been patented and under review for publication.
Innovator
Prof Rakesh K Sharma is PhD from IISc Banaglore (2007) and a postdoc from the Ohio State University. He has been working on clay based catalysts for the last 10 years at IIT Jodhpur. He has published more than 50 papers and has 10 patents on his name. His research area is heterogeneous catalysis with specific focus on environmental remediation and bio-fuel. He is former Head of Department of Chemistry at IIT Jodhpur and is currently Dean(A) – Research & Development.
