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

• DOI: 10.1016/j.jcat.2015.10.007
• Publication Date: 2015-11-12T18:33:34Z
• Authors: Petr Sazama; Lukasz Mokrzycki; Blanka Wichterlova; Alena Vondrova; Radim Pilar; Jiri Dedecek; Stepan Sklenak; Edyta Tabor
• Keywords: Propane

Abstract An Al-rich Co-BEA ∗ zeolite (Si/Al 4.2, Co/Al 0.5) was prepared by organotemplate-free hydrothermal synthesis and [Co(II)(H 2 O) 6 ] 2+ ion exchange. The structure of the Co species and their activity in C 3 H 8 –SCR-NO x were compared to that of Si-rich Co-BEA ∗ (Si/Al 11.3). The high population of AlSiAl sequences in Al-rich BEA ∗ with AlO 4 − facing different channels, contrary to their absence in Si-rich BEA ∗ , results in dehydrated Co-BEA ∗ in easily reducible counter-ion [Co(III)O] + species attached to one AlO 4 − . The high concentration and density of these Co-oxo species in Al-rich Co-BEA ∗ facilitates extra-ordinarily high SCR-NO x rate even under water vapor up to 10 vol.%, twelve-times outperforming Si-rich Co-BEA ∗ . 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 ∗ 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.