Search

The influence of Si doping of high specific-surface-area Ru/TiO 2 catalysts with similar structural properties on the CO 2 reduction reaction was systematically investigated by kinetic measurements, combined with microscopic and spectroscopic methods for ex situ and in situ / operando catalyst characterization. While for undoped Ru/TiO 2 a high-temperature treatment (350 °C) in reaction atmosphere results in a pronounced change of the selectivity from methanation to CO formation via the reverse water-gas shift (RWGS) reaction, CH 4 formation is stabilized by Si doping of the catalyst support. For doping levels around 8 wt%, almost 100% CH 4 selectivity is maintained. Comprehensive catalyst characterization is employed to identify trends in the physical and chemical properties with increasing Si doping and thus physical reasons responsible for the distinct differences in catalyst performance and stability. This work opens a route for improving the stability and selectivity of Ru/TiO 2 catalysts in the CO 2 hydrogenation reaction, a highly relevant application. [Display omitted] • High-surface-area (SSA) Ru/TiO 2 catalysts are highly active for CO 2 hydrogenation. • High-SSA Ru/TiO 2 catalysts are 100% selective for methane formation. • This high selectivity breaks down after temperature excursions during reaction. • Si doping stabilizes selectivity of high-SSA Ru/TiO 2 catalysts for CO 2 methanation. • Catalyst characterization reveals complex origin of the thermal stabilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au loading/particle size affects performance of Au/ZnO catalysts for CO 2 reduction. • Selectivity for methanol formation increases with Au particle size. • Partial overgrowth of the Au NPs during reaction. • Formation of O-vacancies during reaction. • r Overgrowth/vacancy formation increases/decreases with Au loading and particle size. Methanol synthesis by CO 2 reduction is an important approach for energy storage. Aiming at a reduction of the catalyst mass in technical applications, we have investigated the influence of increasing Au loading on the performance of Au/ZnO in methanol and CO formation from CO 2 reduction. Using the same type of ZnO support, increased Au loading resulted also in a pronounced increase in Au particle size. The Au-mass-normalized reaction rate for methanol formation and TOF decrease with increasing Au loading/particle size, while the selectivity for methanol formation increases. CO adsorption monitored by in situ FTIR revealed a pronounced decrease of the accessible Au surface area during reaction, independent of the Au loading, pointing to a partial encapsulation of the Au nanoparticles by a partly reduced ZnO x , as described by SMSI effects. Possible reasons responsible for these effects and Au loading/size effects therein are discussed, strategies for future work are outlined. [ABSTRACT FROM AUTHOR]