Beneficial effect of adding γ‐AlOOH to the γ‐Al2O3 washcoat of a PdO catalyst for methane oxidation

다국어 초록 (Multilingual Abstract)

The beneficial effect of adding γ‐AlOOH to the γ‐Al2O3 washcoat of a ceramic cordierite (2MgO · 2Al2O3 · 5SiO2) monolith, used to support a PdO catalyst, is reported for methane oxidation in the presence of water at low temperature (<500°C). The mini‐monolith (400 cells per square inch (CPI), 1 cm diameter × 2.54 cm length; ~52 cells) was washcoated using a suspension of γ‐Al2O3 plus boehmite (γ‐AlOOH), followed by calcination and then deposition of Pd by wet impregnation. An optimum solid content of 25 wt% in the washcoat suspension was used to obtain a ~25 wt% washcoat on the monolith. The presence of γ‐AlOOH enhanced the thermal and mechanical stability of the washcoat, provided that the γ‐AlOOH content was <8 wt%. Temperature‐programmed methane oxidation (TPO) showed that the addition of γ‐AlOOH to the γ‐Al2O3 washcoat decreased the catalyst activity. However, when H2O (2 vol% and 5 vol%) was present in the feed gas, the γ‐AlOOH improved the catalyst activity and stability. A γ‐AlOOH content of ~5 wt% in the washcoat was determined to provide the highest catalyst activity and stability for CH4 oxidation in the presence of water.
γ‐AlOOH to the washcoat improves the activity of the PdO catalyst for CH4 oxidation in the presence of water (5 vol% H2O)