Unprecedented propane–SCR-NO x activity over template-free synthesized Al-rich Co-BEA ∗ zeolite

• Published in: Journal of catalysis 2015-12, Vol.332, p.201-211
• Main Authors: Sazama, Petr, Mokrzycki, Lukasz, Wichterlova, Blanka, Vondrova, Alena, Pilar, Radim, Dedecek, Jiri, Sklenak, Stepan, Tabor, Edyta
• Format: Article
• Language: English
• Subjects: Catalysis; Chemical synthesis; Propane; Zeolites
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2015.10.007

Display Omitted * Al-rich compared to Si-rich Co-BEA[low * ] provides extraordinarily high SCR activity. * The most active site is [Co(III)O]+ attached to one AlO4 - of AlSiAl sequence. * High density of [Co(III)O]+ causes synergism in SCR-NO x . * 12 times increased reaction rate and 5 times higher TOFCo for Al-rich Co-BEA[low * ] . * The Al-rich Co-BEA[low * ] exceeds previously reported catalysts for C3H8-SCR-NO x . An Al-rich Co-BEA[low * ] zeolite (Si/Al 4.2, Co/Al 0.5) was prepared by organotemplate-free hydrothermal synthesis and [Co(II)(H2O)6]2+ ion exchange. The structure of the Co species and their activity in C3H8-SCR-NO x were compared to that of Si-rich Co-BEA[low * ] (Si/Al 11.3). The high population of AlSiAl sequences in Al-rich BEA[low * ] with AlO4 - facing different channels, contrary to their absence in Si-rich BEA[low * ] , results in dehydrated Co-BEA[low * ] in easily reducible counter-ion [Co(III)O]+ species attached to one AlO4 - . The high concentration and density of these Co-oxo species in Al-rich Co-BEA[low * ] facilitates extra-ordinarily high SCR-NO x rate even under water vapor up to 10vol.%, twelve-times outperforming Si-rich Co-BEA[low * ] . The five-to-six times increased TOF and easier reducibility suggest a synergetic redox effect of water-resistant Co-oxo species. The Al-rich Co-BEA[low * ] provides the highest reaction rate at conditions of wet NO x streams, exceeding that previously reported for metal ion/oxo zeolite catalysts, with a high selectivity to molecular nitrogen and efficient utilization of propane.