The role of palladium salt precursors in Pd-PdO/CeO2 catalysts prepared by dry milling for methane oxidation

Pd/CeO2 Catalysts Prepared by Solvent-free Mechanochemical Route for Methane Abatement in Natural Gas Fueled Vehicles

“…It is possible that the evaluated catalyst is affected to a greater extent by aging under a rich/lean oscillating regime compared to the conventional IW samples, but a negative effect of the washcoating process cannot be excluded; catalytic performance of 4PdCe1473M might be influenced by the preparation and coating process, which involves a series of oxidative steps shown to be detrimental for these catalytic materials. 36 An optimized washcoating procedure should be appropriately tuned for this catalytic system. Nevertheless, improving the aging resistance of the milled samples would be necessary for the sample preparation technique to have practical importance.…”

“…The methane conversion curves recorded at high space velocity (≈480 000 h −1 ) reported in Figure 4 clearly point out that the highest methane oxidation activity is obtained by 1PdCe1473M. Indeed, as reported in our previous work, 36 the combination of Pd(OAc) 2 milled on low surface area ceria (calcined at 1473 K, ∼4 m 2 /g surface area) simultaneously ensures low temperature methane activation and a negligible activity drop at temperatures above 900 K. This was attributed to a specific Pd 0 /Pd 2+ arrangement stabilized on the ceria surface, promoting surface oxygen mobility and resulting in higher methane oxidation reaction rate compared to IW samples where Pd 2+ /Pd 4+ in addition to low amounts of Pd 0 species were found by AP-XPS. 38 The trend confirms the results of activity tests performed under ideal reaction conditions and lower space velocity (0.5% CH 4 , 2% O 2 in He, GHSV ≈ 180 000 h −1 , Figure S2).…”

“…Indeed, as reported in a previous work, an oxidizing pretreatment in air negatively affects the methane oxidation performance of Pd/ CeO 2 milled samples. 36 The activity of the 4PdCe1473M coated monolith was compared to reference 4PdCe873IW and 4PdAl873IW counterparts under methane oxidation and steam reforming conditions, before and after synthetic aging. The performance of degreened samples is shown in Figure 8 panels a and c for methane oxidation and steam reforming, respectively.…”

“…[31][32][33][34] We previously reported a novel solvent-free mechano-chemical route for the synthesis of highly active methane oxidation Pd/CeO2 catalysts starting from either metallic Pd nanopowders or Pd salts. 35,36 The developed synthesis procedure resulted in catalytic materials with a peculiar coreshell morphology, displaying enhanced methane oxidation activity at low and high temperature and improved stability in the presence of excess steam. The enhanced reactivity is strongly dependent on the synthesis approach 37 and can be ascribed to highly dispersed Pd/PdO species in close interaction with ceria, embedded in an amorphous shell structure that likely contributes to their stability throughout reaction.…”

Monometallic Cerium Layered Double Hydroxide Supported Pd-Ni Nanoparticles as High Performance Catalysts for Lignin Hydrogenolysis

“…Afterwards, the impregnated support is dried overnight at 105 • C under air to allow the water to evaporate. Finally, the dried catalyst is calcined at 500 • C (heating at 10 • C/min) for 4 h under air, converting the metal nitrates into their respective metal oxides [47,48]. The catalysts are denoted as PdNi-Ce-LDH-xxx where 'xxx' indicates the calcination temperature of the Ce-LDH support, prior to metal impregnation, as described in Section 2.1.1.…”