%0 Journal Article
%T The Impact of CeO2 Loading on the Activity and Stability of PdO/¦Ã-AlOOH/¦Ã-Al2O3 Monolith Catalysts for CH4 Oxidation
%J Catalysts | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/catal9060557
%X This study reports on the activity and stability of PdO/¦Ã-AlOOH/¦Ã-Al 2O 3 monolith catalysts, promoted with varying amounts of CeO 2, for CH 4 oxidation. Although the beneficial effects of CeO 2 have been reported for powdered catalysts, this study used a cordierite (2MgO.2Al 2O 3.5SiO 2) mini-monolith (400 cells per square inch, 1 cm diameter ¡Á 2.5 cm length; ~52 cells), washcoated with a suspension of ¦Ã-Al 2O 3 combined with boehmite (¦Ã-AlOOH), followed by sequential deposition of Ce and Pd (0.5 wt.%) by wetness impregnation. The monolith catalysts¡¯ CH 4 oxidation activity and stability were assessed in the presence of CO, CO 2, H 2O and SO 2 at low temperature (¡Ü550 ¡ãC), relevant to emission control from lean-burn natural gas vehicles (NGVs). The CeO 2 loading (0 to 4 wt.%) did not significantly impact the adhesion and thermal stability of the washcoat, but CeO 2 reduced the inhibition of CH 4 oxidation by H 2O and SO 2. The catalyst activity, measured by temperature-programmed methane oxidation (TPO) in a dry feed gas with 0.07 vol.% CH 4, showed that adding CeO 2 to the ¦Ã-AlOOH/¦Ã-Al 2O 3 washcoat suppressed the activity of the catalysts; whereas, CeO 2 improved the catalyst activity when H 2O (2 and 5 vol.%) was present in the feed gas. Moreover, adding CeO 2 decreased catalyst deactivation that occurred in the presence of 10 vol.% H 2O and 5 ppmv SO 2 at 500 ¡ãC, measured over a 25 h time-on-stream (TOS) period. The highest catalyst activity and stability for CH 4 oxidation in the presence of H 2O was obtained by adding 2 wt.% CeO 2 to the washcoat. View Full-Tex
%U https://www.mdpi.com/2073-4344/9/6/557