Study of the effect of Gd-doping ceria on the performance of Pt/GdCeO2/Al2O3 catalysts for the dry reforming of methane

Highly active and stable Ni dispersed on mesoporous CeO2-Al2O3 catalysts for production of syngas by dry reforming of methane

“…However, the intensity of this line starts to decrease when the sample is heated at 200 °C and it is no longer observed after reduction at 800 °C. According to the literature [13,31], the reduction of ceria-based materials leads to the shift of the lines characteristic to CeO2 to lower angles due to the conversion of Ce 4+ to Ce 3+ species but the intensities of these lines do not change. Therefore, what is causing the disappearance of the CeO2 lines during reduction?…”

Pt nanoparticles embedded in CeO2 and CeZrO2 catalysts for biogas upgrading: Investigation on carbon removal mechanism by oxygen isotopic exchange and DRIFTS

“…Furthermore, the use of transition metals as dopants promotes the oxygen mobility, permitting the participation of bulk oxygen species in the process. Fonseca et al [19] reported the impact of the presence of mixed oxide by studying the behavior of Pt/Al2O3 and Pt/CexGd1-xO2/Al2O3 in the dry reforming of methane. The formation of high amount of carbon observed on Pt/Al2O3 was avoided for Pt/Ce0.8Gd0.2O2 due to the presence of oxygen vacancies generated by the Ce 4+ reduction.…”

Exsolution of Metallic Ru Nanoparticles from Defective, Fluorite-Type Solid Solutions Sm2RuxCe2–xO7 To Impart Stability on Dry Reforming Catalysts

“…In addition, supported nanoparticles should ideally have a uniform and controlled size and be resistant to sintering under relevant operating conditions. This is yet a challenge for noble-metal-based DRM catalysts. − DRM catalysts are commonly prepared by depositing a precursor of the active metal on a metal oxide support via wetness impregnation followed by a reduction step to form supported metal nanoparticles. However, often, this method does not allow control of the dispersion and size of the nanoparticles and does not stabilize them against sintering with TOS. , Approaches to reduce sintering have included post-synthetic encapsulation or partial embedding of the active metal in a thin layer of oxides with high Tammann temperatures. , These strategies indeed improved the thermal stability of the DRM catalysts, however, at the expense of a reduced specific activity due to the partial blocking of active sites or an increased mass transfer resistance. − Recently, the so-called reductive exsolution (or reductive segregation) approach yielding highly dispersed supported metallic nanoparticles has been introduced. − This method exploits the exsolution of a late transition metal from a host oxide structure in a H 2 atmosphere and is typically applied to substituted perovskite ABO 3 phases where a late transition metal replaces the B site metal. , As a result, highly dispersed nanoparticles of the exsolved late transition metal can be obtained on the surface of the perovskite phase with a uniform size distribution, owing to the inherent homogeneity of the parent solid solution oxide. − ,,, An interesting feature of exsolved nanoparticles is their socketing in the perovskite surface, a manifestation of a strong interaction between the metal and the oxide support that could reduce the mobility of the active metal under harsh reaction conditions and limit sintering of the active phase. ,, Importantly, investigations by transmission electron microscopy of the metal phases, reductively exsolved from substituted perovskites, suggest that the entrapment of metallic nanoparticles in the bulk of a host material is a viable scenario, and it should be minimized or avoided to make all exsolved metal accessible for gas-phase catalysis. , To date, mostly perovskite structures have been utilized for the reductive exsolution, while other crystalline oxides, such as ceria-based materials with fluorite-related structures, have remained underexplored. − In general, these fluorite-related structu...…”