Porous Metal Oxide Based Nanocomposite Catalysts for the Selective Conversion of Harmful NO_x to Valuable NH₃

Abstract

The soft-templating approach with the self-assembly of amphiphilic organic molecules is introduced as our methodology for synthesizing mesoporous metal oxides, e.g., alumina (Al₂O₃) and titania (TiO₂). Our efficient optimization of the synthetic conditions based on the common spin-coating process leading to fast evaporation of solvents has generalized a smart synthetic method combined with a temperature-controllable scalable spray-drying process for recovering porous metal oxide powders with high specific surface area. To illustrate the use of mesoporous metal oxides as catalyst supports, the chemical composition of nanocomposite catalysts was surveyed for synthesizing gaseous ammonia (NH₃) through the hydrogenation of solid-state nitrogen oxides (NO_x). The porous metal oxide based nanocomposite catalysts were prepared by one-pot doping of noble metal catalyst and subsequent impregnation of additional component for the storage of NO_x. The reaction process was designed for the selective synthesis of NH₃ by an alternate gas-switching operation between storage of NO_x and reduction by H₂.