Pd/SrFeTi O as Environmental Catalyst: Purification of Automotive Exhaust Gases.

Environmental catalysts are required to operate highly efficiently under severe conditions in which they are exposed to reductive and oxidative atmospheres at high temperatures. This study demonstrates that SrFeTi O-supported Pd catalysts exhibit high catalytic activities for NO reduction with CH and CO in the presence of O, which is a model reaction for the purification of automotive exhaust gases. Catalytic activity is enhanced with increasing Ti content, and the highest activity is observed for Pd/SrFeTiO among the examined catalysts. The state of the loaded Pd species can be controlled by the Fe/(Fe + Ti) ratio in SrFeTi O, and highly active PdO nanoparticles are properly anchored on SrFeTiO. The Ti-rich Pd/SrFeTiO shows significantly higher catalytic activity and is more thermally stable than the conventional Pd/AlO, which has a high surface area. Since Fe-rich SrFeTi O has the high oxygen storage capacity, its response capabilities to atmospheric fluctuations were evaluated by changing the oxygen concentration during NO reduction. As a result, Fe-rich Pd/SrFeTiO retains its high NO-reduction activity for longer times even under oxidative conditions, when compared to SrFeO or Ti-rich Pd/SrFeTi O. The oxygen storage properties of Pd/SrFeTiO allow it to effectively act as an oxygen buffer for NO reduction. These properties ensure that the SrFeTi O support, with both high thermal stability and oxygen storage capacity, is a very useful environmental-catalyst material.