High-performance CeO2/halloysite hierarchical catalysts with promotional redox property and acidity for the selective catalytic reduction of NO with NH3

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-06, Vol.390, p.124251, Article 124251
• Main Authors: Chen, Liang, Wang, Qiaoli, Wang, Xiaoxiang, Cong, Qiliang, Ma, Heyao, Guo, Tianjiao, Li, Sujing, Li, Wei
• Format: Article
• Language: English
• Subjects: Acidity; CeO2; Halloysite; NH3-SCR; Oxygen vacancy
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.124251

[Display omitted] •CeO2/HAT owns enhanced oxygen vacancies and Brønsted acidity due to defect-riched nano-ceria and Al-OH riched HAT.•CeO2/HAT inhibits NH3 over-oxidation via an occupation/release of oxygen vacancies (vo) and hydroxyls (–OH).•Both Eley-Rideal and Langmuir-Hinshelwood mechanisms exist in the NH3-SCR reaction over CeO2/HAT.•CeO2/HAT has renewable activity after SO2/H2O treatment as Brønsted acidity increasing via CeO2 sulfuration. Earth-abundant and environmental-friendly ceria with excellent redox ability, rich surface oxygen vacancies and high oxygen storage capacity was wildly used as catalysts for NH3-SCR. A high-performance deNOx catalyst based on CeO2 decorated halloysite (HAT) synthesized via a conventional solvothermal method was originally designed and developed in this work. The CeO2/HAT exhibited a high NOx removal efficiency of > 95% and N2 selectivity of > 98% over a wider temperature range (275–400 °C) under a high gas hourly space velocity of 177,000 h−1. As revealed by XPS and LT-ESR, HAT fabrication contributed to the enrichment of active oxygen species and vacancies according to the hydroxyl-riched octahedral sheet (Al-OH) groups as well as the defect-riched nano-ceria synthesized via the constrained effects of steric hindrance. The enriched oxygen vacancies led to the reducibility strengthen of ceria, benefiting NH3 activation and avoiding the over-oxidation. In situ DFRITS demonstrated that HAT fabrication resulted in the great enrichment of Brønsted acidity and a rapid reactivity of NH3-intermediates, leading to the high NOx removal efficiency and N2 selectivity even at high temperatures.