High-temperature combustion of CH4 over PdO/Al2O3: kinetic measurements in a structured annular reactor

An Experimental and Kinetic Modelling Study for Methane Oxidation over Pd-based Catalyst: Inhibition by Water

“…Compared with T 50 obtained under dry conditions, the increase was as dramatical as 98 and 181 °C for the heating and cooling cases. The reaction rate for the methane oxidation (R1, Table 2) contained an inhibition term for water, in a similar way as was shown in the study by Groppi et al [22,23] and Fernández et al [24]. This term provided an immediate effect of water and only depended on water concentration without changing over time.…”

“…The model also contains a water inhibition term in the same way as the pseudo LHHW model that Groppi et al [22,23] have described. However, this model could not account for the slow deactivation observed during transient experiments.…”

“…There are also a few kinetic models available for methane oxidation in the presence of water vapour. For methane oxidation most commonly the Langmuir-Hinshelwood-Hougen-Watson (LHHW) type of the rate equations is used in literature [22][23][24][25][26][27][28]; however, Mars-van Krevelen (MVK) based equations can also be used to describe mechanism of methane oxidation [29,30]. The oxidation of CH 4 over PdO is strongly inhibited by H 2 O, with a negative reaction order (−1) [15].…”

“…The oxidation of CH 4 over PdO is strongly inhibited by H 2 O, with a negative reaction order (−1) [15]. Groppi et al [22,23] used a pseudo LHHW kinetic model R w = K r C CH 4 ∕ 1 + K H 2 O C H 2 O to describe methane oxidation over PdO/Al 2 O 3 . The model could adequately describe the steady state conversion of methane when varying methane and water concentrations.…”

EFFECTS OF H2O AND CO2DILUTION ON THE CATALYTIC AND GAS-PHASE COMBUSTION OF METHANE OVER PLATINUM AT ELEVATED PRESSURES

“…Previous works have investigated experimentally the effect of water on the Pd (Ciuparu and Pfefferle, 2001;Groppi et al, 2001;Ibashi et al, 2003;Kikuchi et al, 2002;van Giezen et al, 1999) and to a lesser extent on the Pt reactivity (Gelin et al, 2003;Urfels et al, 2004) during the complete oxidation of methane. The impact of CO 2 was also addressed in some of the Pd studies (Ibashi et al, 2003;van Giezen et al, 1999).…”