Professor Toru Murayama at Tokyo Metropolitan University (Tokyo, Japan; www.haruta-masatake.ues.tmu.ac.jp), in collaboration with Chugoku Electric Power Co., Inc., has developed a vanadium oxide catalyst that removes oxides of nitrogen (NOx) from fluegas generated by the combustion of heavy fuel oil and coals. The developed V2O5 catalyst has a high specific-surface area of 40 m2/g, which enables the deNOx reaction to take place at a temperature of around 150°C. This is considerably lower than the 400°C required by existing catalysts (0.5–2 wt.% V2O5, with surface areas of 2.5 m2, deposited on a TiO2 system). The lower temperature operation is also expected to enable the catalyst to have a longer lifetime, thereby lengthening the time required for changeout. Conventional catalysts operating at the higher temperatures need to be changed every 2–4 years, which costs several million dollars per changeout, says Murayama.
The new catalyst is fabricated to have a large surface area by calcination of ammonium metavanadate precursor with oxalic acid. The catalyst is composed solely of V2O5, and shows a 90% selectivity for the reduction of NOx. It is suitable for low-temperature deNOx of fluegas when poisons, such as sulfur dioxide, have first been removed. So far the researchers have demonstrated that the catalytic performance is unchanged after treating fluegas for 7 days. They are now planning to perform durability testing at a coal-fired power plant through 2021, with commercial applications by 2024. Besides power plants, the catalyst may also be suitable for treating the exhaust from incinerators, as well as helping ships to meet the tighter international-maritime regulations.