The structure of Co species in novel active and selective Co/MCM41 catalyst in the COProx reaction prepared by supercritical CO2 reactive deposition

A.V. BOIX; ASPROMONTE, SOLEDAD G.; ALONSO, ESTHER; J.M. RAMALLO LOPEZ; M. MIZRAHI

Campinas

Congreso; 27th Annual Users Meeting; 2017

CNPEM-LNLS

The deposition of catalytically active sites on supports with high dispersion is an important and effective strategy for Synthesis the design of catalysts. Conventional methods such as impregnation techniques often generate agglomerations or large particles with broad size distribution in the mesopores and/or on the external surface of the porous catalyst. The incipient wetness impregnation (IWI) method allows a good control on metal loading but a poor control on metallic dispersion.1, 2 Thus, it is important to study and analyze different ways to introduce the active phase in the mesoporous support.An interesting method for incorporating active phases on catalyst supports is the reactive deposition using supercritical fluids (SCFRD). It is a promising method to deposit nanoparticles and films on inorganic porous supports, polymer substrates and carbon nanotubes.3, 4 This process involves the dissolution of an organometallic precursor in a supercritical fluid (SCF), the impregnation of the substrate by exposure to this solution, and the subsequent decomposition of the precursor. CO2 is the most commonly used supercritical fluid (scCO2) for aterialsynthesis because it is non-toxic, non-reactive, nonflammable and inexpensive. Under supercritical conditions, CO2 as a solvent has intermediate properties between gases and liquids. The gas-like diffusivity and viscosity of scCO2 arefavorable for rapid diffusion and permeation into mesoporous substrates, whereas the liquid-like density allows the dissolution of a wide range of organometallic precursors. The zero surface tension of scCO2 allows a better penetration and wetting of pores than liquid solvents and avoids the pore collapse which can occur on certain structures. The simple removal from the substrate by controlled decompression is performed without leaving any residue on the support.5, 6The goal of the present study is to investigate and compare the catalytic properties of the cobalt-MCM41 catalysts prepared by methods (i) template-ionic exchange (TIE), (ii) incipient wet impregnation (IWI) and (iii) supercritical CO2 reactive deposition (SCFRD) in the total and preferential CO oxidation in reductive atmosphere to purify H2 streams.