Catalytic Activity and Stability over Nanorod-Like Ordered Mesoporous Phosphorus-Doped Alumina Supported Palladium Catalysts for Methane Combustion

Abstract

Nanorod-like phosphorus-doped ordered mesoporous γ-alumina (OMA), which has abundant ordered pore channels in the nanorods, was rapidly synthesized through a modified sol–gel strategy without use of any mineral acids. Highly dispersed Pd-based catalysts were synthesized by taking as-obtained phosphorus-doped OMA materials as carriers for methane combustion. The crystallization temperature of γ-Al2O3 was increased by phosphorus doping. The surface acidity properties of γ-Al2O3 were modified upon phosphorus incorporation, which had a significant effect on catalyst activities, and this influence was much more conspicuous for the supports calcined at high temperature. The incorporation of phosphorus adjusted the distribution of palladium active species and the reducibility of catalysts, synergistically affecting the low-temperature catalytic performance. Pd/6P-OMA catalyst demonstrated enhanced low-temperature catalytic properties and stability in the 13-cycle stability and long-term stability tests. During the reaction cycles, the total CH4 conversion temperature for Pd/6P-OMA catalyst was as low as 345 °C, which could be reduced to 321 °C via hydrogen reduction treatment. In comparison with the catalyst without dopant, the Pd/6P-OMA catalyst also exhibited higher hydrothermal stability in the presence of excess water vapor in the feed.

Dehydrogenation of 2-[(n-Methylcyclohexyl)Methyl]Piperidine over Mesoporous Pd-Al2O3 Catalysts Prepared by Solvent Deficient Precipitation: Influence of Calcination Conditions

“…The declines in the BET surface area and pore volume and increase in the pore size can be explained by the growth of alumina particles. A similar trend was noted in earlier literature [23]. Notably, the capillary condensation shifted toward higher relative pressures as the calcination temperature increased, suggesting an enlargement in the pore size due to development of Al 2 O 3 particles.…”

Synthesis of a Highly Stable Pd@CeO2 Catalyst for Methane Combustion with the Synergistic Effect of Urea and Citric Acid

“…In contrast, the noble metal catalysts, especially the supported palladium catalysts, 14,15 exhibit high catalytic activity for methane complete combustion. 16,17…”

Pd-Nanoparticles@layered double hydroxide/reduced graphene oxide (Pd NPs@LDH/rGO) nanocomposite catalysts for highly efficient green reduction of aromatic nitro compounds

“…6–9 Recently, solid matrices supported Pd NPs have been probed as an encouraging approach for the fabrication of robust and durable heterogeneous catalysts with superior advantages over their homogeneous counterparts. 10 Various solid matrices such as carbon, 11 graphene, 12 zeolites, 13 alumina, 14 silica, 15 and layered materials have been employed for the fabrication of highly stable size-controlled metal NPs. Among all, layered double hydroxides (LDHs) offer a high surface area, rich intercalation chemistry and flexible compositional diversity in the synthesis of size-controlled Pd NPs.…”