Boosting water activation determining-step in WGS reaction on structured catalyst by Mo-doping

• Published in: Catalysis today 2022-01, Vol.383, p.193-204
• Main Authors: García-Moncada, Nuria, Jurado, Lole, Martínez-Tejada, L. Marcela, Romero-Sarria, Francisca, Odriozola, José Antonio
• Format: Article
• Language: English
• Subjects: Mo-doped mixed oxide; Proton conductor; Pt catalyst; Water activation; WGS
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2020.06.003

[Display omitted] •Mo- Eu-doped ZrO2 acts as proton conductor increasing the WGS catalyst’ activity.•The structuration of the catalyst leads to higher conversions.•Structured catalysts demonstrate the promoter effect is caused by proton conductor.•Promoted WGS catalysts very promising for H2 technology mobile devices. Proton conductors Mo-Eu-Zr mixed oxide systems were synthesized and further mixed with a conventional Pt/CeO2/Al2O3 catalyst to develop a highly efficient water-gas-shift (WGS) catalyst. The designed catalyst, once structured, allows reach the equilibrium conversion at medium temperatures (∼350 °C) at 80 L·g−1 h−1 space velocity. The ability of the proton conductor to maintain an elevated water concentration at the metal-support interface by Grotthuss’ mechanism boosts the catalytic activity in WGS reaction. The Mo-containing proton conductor is extensively characterized allowing to establish the formation of molybdenum oxide phases nucleating on top of the Eu sites in Eu-Zr oxide solid solution. [MoO4]2− to [Mo7O24]6− clusters nucleates at low Mo contents resulting in a α-MoO3 layer on increasing its content. In presence of H2, Mo-bronzes are formed from ∼200 °C enhancing water concentration at the surfaces and boosting the catalytic activity in the WGS reaction. These results pave the way for developing lower volume WGS reactors.