Selective oxidation of methane to formaldehyde: comparison of the role of promoters in hydrocarbon rich and lean conditions

Active oxygen in selective oxidation catalysis

“…Similar products, although with a lower selectivity, were observed over the same type catalysts for the oxidation of CH 4 and C 2 H 6 with O 2 [34,35].…”

“…In addition to selective oxidation of methane and ethane with O 2 over V 2 O 5 and MoO 3 oxides mentioned earlier [34,35], of particular interest are recent studies on oxidehydrogenation of propane carried out jointly by two research groups of Bell and Iglesia [87][88][89][90][91][92][93][94][95]. These works present a thorough investigation of the reaction mechanism over supported V 2 O 5 , MoO 3 , WO 3 and Nb 2 O 5 oxides.…”

“…Therefore, the authors [17,[25][26][27][28][29][30][31][32][33][34][35] concluded that their formation in catalytic reactions also proceeds due to O À radicals.…”

Kinetics of the partial oxidation of methane to formaldehyde on silica catalyst

“…Then, as a consequence of marked differences in the reactivity of the silica samples, the addition of promoters might have either a positive or negative effect on the activity of the carrier. In particular, while V O pro- 2 5 Ž motes the reactivity of any silica samples Spencer and Pereira, 1989;Kennedy et al, 1992;Kartheuser et al, 1993;Parmaliana et al, 1993Parmaliana et al, , 1994Parmaliana et al, , 1995aKoranne et al, 1993Koranne et al, , . 1994Arena et al, 1995 . MoO enhances the performance 3 Ž of sol-gel and pyrolitic samples Spencer and Pereira, 1987;Sun et al, 1992;Mauti and Mims, 1993;Parmaliana et al, .…”

“…Parmaliana and Arena, 1997 . Although the many attempts to shed light on the nature of the active sites and reaction mechanism, the role of the cata-Ž . lyst lattice oxygen ions LOI in the CH activation and 4 Ž HCHO formation processes is still controversial Kennedy et al, 1992;Kartheuser et al, 1993;Mauti and Mims, 1993;Koranne et al, 1993Koranne et al, , 1994Parmaliana et al, 1993Parmaliana et al, , 1995aFaraldos et al, 1996;Arena et al, 1994Arena et al, , 1997Herman et al, . Ž 1997 .…”