Nanostructured perovskite-based oxidation catalysts for improved environmental emission control

Abstract

Global concerns over environmental pollution have resulted in increasingly stringent regulations to control the levels of critical air pollutants, such as, carbon monoxide (CO), nitrogen oxide species (NOx), volatile organic compounds (VOC) and particulate matter (PM). These pollutants are removed by heterogeneous catalysis and the platinum group metals (PGM) remain the catalysts of choice but this situation is now complicated by the requirement for higher performance at lower costs while the PGM are experiencing escalating prices. A solution to this problem is the use of nanostructured perovskite-based Nanoxite™ catalysts engineered with unique structural features and high surface areas that enable higher catalytic efficiency at lower temperatures without sacrificing durability performance. In fact, Nanoxite is a “catalytic washcoat” product in that it simultaneously functions as the emission control catalyst while providing the bulk of the washcoat. As a result, both the PGM level and the amount of conventional washcoat materials are simultaneously reduced. Each powder particle possesses a hierarchical structure where larger micron sized particles hold the < 40 nanometer size perovskite grains. This desired arrangement facilitates easy powder handling and eliminates reactivity typically associated with discrete Nanograin materials. These perovskite-based catalyst formulations are applicable to both diesel engine and stationary emission control with respect to CO / VOC oxidation and the management of NOx and PM.