Stable and Active Mixed Zr–Ce Oxides for Catalyzing the Gas Phase Oxidation of HCl

Synthesis and Physicochemical Characterization of Ce1−xGdxO2−δ: A Case Study on the Impact of the Oxygen Storage Capacity on the HCl Oxidation Reaction

“…No broadening and no shifting of the band position is observed. This result is in agreement with the results from (Ce 0.9 Zr 0.1 )O 2 with a Zr content of 10 at % . Ceria–gadolinia solid solutions show the cubic fluorite structure without significant changes.…”

Electrospun ceria-based nanofibers for the facile assessment of catalyst morphological stability under harsh HCl oxidation reaction conditions

“…Unlike the pure and the 10% Zr-doped CeO 2 nanofibers, all other compositions of Zr-doped CeO 2 nanofibers were morphologically stable even under "harsh" feed composition as indicated by their unchanged appearance in SEM images before and after the reaction and also by XRD. According to extended Raman and XRD studies [42], the crystallographic structures of the Ce x Zr 1-x O 2 fibers agree with those expected of the bulk solid solutions [43] and with the corresponding phase diagram [44]. The structure of the Ce x Zr 1-x O 2 fibers (x<0.9) is basically not affected by the reaction; no sign of chloride formation is discernible in XRD.…”

“…5. From the time-dependent catalytic and stability data, it is clear that the activity is stable after an induction period of about 30 h for all Ce x Zr 1-x O 2 fibers [42]. Unlike the pure and the 10% Zr-doped CeO 2 nanofibers, all other compositions of Zr-doped CeO 2 nanofibers were morphologically stable even under "harsh" feed composition as indicated by their unchanged appearance in SEM images before and after the reaction and also by XRD.…”

“…These conditions can even affect the catalyst itself: chlorination of the catalyst (possibly with subsequent chloride evaporation) is known to be the cause of the loss of activity in some Deacon catalysts [17,45]. On the one hand, cerium trichloride that forms under certain conditions during the operation of cerium dioxide HCl oxidation catalysts [25,42] is not volatile at the temperature used in the experiments (703 K). On the other hand, cerium trichloride is inactive in the Deacon reaction [17,19], and its formation should therefore be avoided.…”

“…To evaluate the influence of temperature on the chlorination of CeO 2 under HCl oxidation conditions, we compare two pure ceria nanofiber samples (synthesized as described in [42]) after 60 h of operation under "harsh" feed composition at 703 K. One of the two samples was put through the "inert thermal transient", the other through the "reactive" one. In addition to the "reactive transient", the second sample was also used for activation energy measurement in the same experiment; thus, after 60 h of constant temperature two downward temperature sweeps with brief returns to 703 K were performed (please refer to Fig.…”