Unprecedented propane-SCR-NOx activity over template-free synthesized Al-rich Co-BEA* zeolite

An Al-rich Co-BEA* 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-NOx were compared to that of Si-rich Co-BEA* (Si/Al 11.3). The high population of AlSiAl sequences in Al-rich BEA* with AlO4- 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 AlO4-. The high concentration and density of these Co-oxo species in Al-rich Co-BEA* facilitates extra-ordinarily high SCR-NO 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 NOx streams, exceeding that previously reported for metal ion/oxo zeolite catalysts, with a high selectivity to molecular nitrogen and efficient utilization of propane. (C) 2015 Elsevier Inc. All rights reserved.