The formation of carbon surface oxygen complexes by oxygen and ozone. The effect of transition metal oxides

✍ Scribed by G. Mul; J.P.A. Neeft; F. Kapteijn; J.A. Moulijn

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 140 KB
• Volume: 36
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/s0008-6223(97)00209-1

✦ Synopsis

Various surface oxygen complexes (SOCs) have been identified by DRIFT spectroscopy on the surface of carbon black (Printex-U ) after partial non-catalytic conversion in 10% O 2 in Ar and ozone. An in situ DRIFT analysis of the oxidation of fullerene C 60 showed the formation of similar functionalities and validated the use of C 60 as a carbon black model compound for DRIFT spectroscopic studies, although C 60 is more reactive towards oxygen than carbon black. Ex situ DRIFT analyses of partially converted catalyst/carbon black mixtures and in situ analyses of catalytic fullerene C 60 oxidation, revealed that several transition metal oxides (Cr 2 O 3 , MoO 3 , V 2 O 5 and CuO) promote the formation of SOCs. Fe 2 O 3 and Co 3 O 4 do not enhance the formation of SOCs in 10% O 2 in Ar and prevent the formation of SOCs on carbon black samples in ozone. Reaction of carbon black with oxygen associated with metal oxides (carbothermic reduction) does not yield SOCs. Apparently, lattice oxygen is not directly involved in the catalytic formation of these complexes. Indications for chemical interactions between metal oxides and either carbon black or C 60 , such as M-O-C bonds, have not been found. Spill-over of activated oxygen from the Cr 2 O 3 , MoO 3 , V 2 O 5 and CuO surfaces onto the carbon black surface is likely to explain the catalytic formation of SOCs.