1999, Volume 2, Issue 3+4
Composite Carbon - Copper with High Selectivity for Oxigen Removal
National Institute of Cryogenics and Isotope Separation, Rm. Valcea
Carbon molecular sieves (CMS) can be modified by copper compounds to selective sorbents for oxygen. Their preparation involves pyrolysis a suitable precursor, such as walnut shells followed by heating in a reducing gas. Through highly dispersed copper in carbon molecular sieves results derived composite with enhanced catalytical and oxygen sorption property. The results indicate that the molecular sieving properties of the copper modified CMS preparation are not significantly altered due to copper addition. Small changes in these properties are expected, but the addition of the metal oxides to the carbons is one of the approaches used in tailoring such properties. The adsorption of oxygen at near room temperature on the sorbents CMS; CMS-Cu-1; CMS-Cu-2 is conditioned by heating at 300°C and vacuum.
When temperature is significantly above room temperature, the physical adsorption for most gases on all the sorbents considered here is negligible. Howere the copper containing sorbents upon reduction can provide oxygen chemosorption sites. Oxygen chemosorption on reduced copper is given by the formation of copper oxide (CuO). The results obtained prove that the addition of copper enhanccs significantly the removal of oxygen from a gas mixture, such as N2-O2 or Ar-O2.
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