Co/MCM41 catalyst in the COProx reaction prepared by supercritical CO2 reactive deposition

JOSÉ RAMALLO LÓPEZ; SOLEDAD ASPROMONTE; ESTHER ALONSO; ALICIA BOIX; MARTÍN MIZHARI

MICROPOROUS AND MESOPOROUS MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 239 p. 147 - 157

1387-1811

Co/MCM41 catalyst with 4.3 wt % Co (Co/sc) has been prepared by supercritical CO2 reactive deposition (?scfrd?) and characterized by different physicochemical techniques. This synthesized methodwas compared with others conventional methodologies such as template-ion exchanged (Co/tie) and incipient wet impregnation (Co/iwi) with similar cobalt content. All the samples were studied as catalystson the CO total oxidation (COTox) and preferential oxidation of CO on H2-rich streams (COProx). Incorporating cobalt with supercritical CO2 leads to a catalyst which produces values of CO conversion similarto those obtained by conventional methods such as incipient wetness impregnation (Co/iwi) or template-ion exchanged (Co/tie). It has been possible to identify different cobalt species present in catalystsdepending on their synthesis methods by Temperature-Programmed Reduction (TPR), X-ray Photoelectronic (XPS), Laser Raman (LRS) and X-ray Absorption (XANES/EXAFS) spectroscopic studies. Allsamples containing a main cobalt species of cobalt (II) coordinated with Si tetrahedral sites form part of mesoporous structure and lesser extent, cobalt orthosilicate on the surface. In addition, Co3O4 speciesdispersed over the MCM41 support were detected for the Co/iwi and Co/sc catalysts.Thus, the combination of Co3O4 nanoparticles and Co(II) sites interacting with the siliceous structure, highly dispersed on the surface and inside the mesoporous support obtained by the ?scfrd? methodresulted in a more active and selective catalyst for the COProx reaction.