Alkali-resistant and aging-tolerant NO_x reduction over self-regulated anti-poisoning catalysts for biodiesel vehicle exhaust purification

Maintaining the ammonia selective catalytic reduction efficiency of catalysts in the co-presence of alkaline metals and high-temperature water vapor among biodiesel vehicle exhaust purification remains a great challenge at present. Here, alkali-resistant and aging-tolerant NO_x reduction over self-regulated anti-poisoning catalysts for biodiesel vehicle exhaust purification had been innovatively demonstrated. TiO₂ pillared natural montmorillonite clays with adequate alkaline metal trapping sites and thermal-stable layered silicate framework was applied to support CeO₂ and WO₃ to obtain a novel NH₃-SCR catalyst that demonstrated outstanding alkaline resistance even under the superimposed effects of hydrothermal aging. It was revealed that Si-O-Si sites among the montmorillonite support could effectively trap the alkaline metal poisons into the layered framework of montmorillonite clays, which can prevent the active component from being damaged and preserve the distinctive layered structure in the presence of high-temperature steam, thus exhibiting remarkable alkaline metal resistance and stronger hydrothermal stability than commercial V₂O₅-WO₃/TiO₂ catalysts. This work paves a way for the development of low temperature and high efficiency denitrification catalysts with alkaline metal resistance and hydrothermal aging tolerance for biodiesel vehicle exhaust purification.