Elucidation of water promoter effect of proton conductor in wgs reaction over pt-based catalyst: An operando drifts study

A conventional Pt/CeO2/Al2O3 catalyst physically mixed with an ionic conductor (Mo-or Eu-doped ZrO2) was tested at high space velocity (20,000 h−1 and 80 L h−1 gcat−1) under model conditions (only with CO and H2O) and industrial conditions, with a realistic feed. The promoted system with the ionic conductor physically mixed showed better catalytic activity associated with better water dissociation and mobility, considered as a rate-determining step. The water activation was assessed by operando diffuse reflectance infrared fourier transformed spectroscopy (DRIFTS) studies under reaction conditions and the Mo-containing ionic conductor exhibited the presence of both dissociated (3724 cm−1) and physisorbed (5239 cm−1) water on the Eu-doped ZrO2 solid solution, which supports the appearance of proton conductivity by Grotthuss mechanism. Moreover, the band at 3633 cm−1 ascribed to hydrated Mo oxide, which increases with the temperature, explains the increase of catalytic activity when the physical mixture was used in a water gas shift (WGS) reaction.Ministerio de Ciencia, Innovación y Universidades ENE2015-66975-C3-2-R, RTI2018-096294-B-C

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

Proton conductors Mo-Eu-Zr mixed oxide systems were synthesized and further mixed with a conventional Pt/CeO/AlO 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 h 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. [MoO] to [MoO] clusters nucleates at low Mo contents resulting in a α-MoO layer on increasing its content. In presence of H, 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

Highly dispersed Rh single atoms over graphitic carbon nitride as a robust catalyst for the hydroformylation reaction

International audienceRhodium-catalysed hydroformylation, effective tool in bulk and fine-chemical synthesis, predominantly uses soluble metal complexes. For that reason, the metal leaching and the catalyst recycling are still the major drawbacks of this process. Single-atom catalysts have emerged as a powerful tool to combine the advantages of both homogeneous and heterogeneous catalysts. Since using an appropriate support material is key to create stable, finely dispersed, single-atom catalysts, here we show that Rh atoms anchored on graphitic carbon nitride are robust catalysts for the hydroformylation reaction of styrene