Low temperature NH3 selective catalytic reduction of NOx over CeOx-biochar catalyst prepared by air oxidation

A highly efficient CeO x -BC 0.6 (BC: biochar. 0.6: mass ratio of Ce/(BC + Ce)) catalyst was prepared by air oxidation for low temperature NH 3 selective catalytic reduction of NO x . The catalytic performance, characterization and reaction mechanism of the CeO x -BC 0.6 were investigated. The results showed that NO x conversion and N 2 selectivity of CeO x -BC 0.6 catalyst obtained by calcining in air were above 90 % at 150–300 °C and 100,000 h −1 . The surface oxygen groups, acid sites and oxygen vacancies were generated by air oxidation treatment, which promoted the adsorption and activation of reactants. NH 3 and NO x were adsorbed on the catalyst surface in the form of NH 4 + , NH 3 + , nitrite and nitrate adspecies. The redox cycles of ketonic carbonyl/phenol (C O/C–OH) pairs and Ce 4+ /Ce 3+ pairs were responsible for the activation of NH 3 and NO x . NH 2 NO and NH 4 NO 2 were the main active intermediates. The reaction of NH 3 selective catalytic reduction of NO x over CeO x -BC 0.6 mainly followed Eley-Rideal mechanism. These results will promote the understanding of mechanism of NH 3 selective catalytic reduction of NO x for biochar-based catalyst prepared by air oxidation.