doi:10.1038/nindia.2015.56 Published online 29 April 2015
By varying the temperature of a constant flow of ammonia gas, researchers have synthesized an efficient solid-base catalyst that can absorb carbon dioxide, a greenhouse gas that contributes to global warming1. This catalyst is a silica oxynitride (SBA-15-oxynitride) and is potentially useful in industrial processes for synthesizing fine chemicals and petrochemicals.
Previous studies had attempted to make silica oxynitrides by changing the temperature and adding methyl groups. But, such modifications destroyed the catalysts’ structures and greatly reduced their surface area, rendering them useless as catalysts.
To make an efficient solid-base catalyst, the researchers added amine groups to silica oxynitrides by heating silica oxynitrides to temperatures of 500, 700, 900 and 1,200 degrees Celsius under a flow of ammonia gas (300 millilitres per minute).
The scientists found that the nitrogen content of the silica oxynitrides increased with increasing reaction temperature. However, they observed that an increase in temperature did not necessarily enhance the catalytic activity of the catalyst ― silica oxynitrides synthesized at 700 degrees Celsius showed the highest catalytic activity, surpassing those of catalysts produced at higher temperatures.
“This technique will help researchers to chemically manipulate various active sites in silica oxynitrides, producing highly active, superior solid-base catalysts for various industries,” says lead researcher Vivek Polshettiwar from Tata Institute of Fundamental Research, Mumbai.
1. Singh, B. et al. SBA-15-Oxynitrides as a solid-base catalyst: effect of nitridation temperature on catalytic activity. Angew. Chem. Int. Ed. 54, 1– 6 (2015)