One can explain based on energy gap of a particular metal ion and activation energy required to carry out particular organic transfermations.

The pure CeO2 is known to be poorly thermostable and undergoes rapid sintering under high temperatures, this greatly decreasing its oxygen storage capacity. Generaly,

Cerium oxide (CeO2) exhibits a strong absorption in the UV range originated from the charge-transfer transition between the O 2p and Ce 4f states in O2- and Ce4+.The charge-transfer transition of Ce4+ions  overlaps with the 4f1 → 5d1 transition of Ce3+ions .

Cerium oxide (CeO2)  shows photocatalytic response mainly based on two fea-tures: due to its low redox potential a Ce ion can easily pass fromCe4+to Ce3+and, secondly, due to its high capacity to store oxygen.

In the heterogenious photocatalysis, the formation of localized states within the band gap owing to oxygen vacancies and increase Ce3+ions.

Cs ions can be exchanged with heteropoly acids it acts as strong solid acid catalysts in dehydration and etherificaion and esterification reactions. Cs ions supported on heteropoly acids its surface area increases and surface acidity increases. Cs exchanged heteropoly acids acts as heterogeneous catalysts.

Three mixed nonstoichiometric oxides :CuO-CeO2;Ce0.5Zr0.5O2 and nMnOx-(1-n)CeO2 are used as catalysts due to three reasons

1. They satisfy the primary conditions of being the heterogeneous catalysts due to their highly porous nature and thus can redily adsorb the gases-especially O2 in their empty interstitial sites. The high porocity asise from the very large difference in their radii[Cu^2=0.72 and Ce^4=0.94; Mn^3=0.66 Ce^4=0.94 and Zr^4=0.80 and Ce^4=0.94A].

2. The other essential condion is that the contituent metal/s should show variable oxidation states which should not differ largely in their energies. In addition, at least one of the oxidation states should be stable.Cerium can form both Ce(III) and Ce(IV) which differ by energy=3547-1949=1598kJ/mol* and Ce(IV) with 4f^0 outermost configuration is very stable.

3. The additional quality of such mixed heterogeneous catalyst is possibility of presence of easy exchange of energies due to CTML, CTLM and from one metal ion to another metal ion.

*It may look strange to find that the third and fourth ionization enrgy difference is found to be least in cerium among their corresponding values for all the 14 lanthanides

I attach a file for your kind perusal to prove the point[Zoom200].

you can check one of our publication:

https://www.researchgate.net/publication/244110812_NO_x_storage_and_reduction_properties_of_PtCe_x_Zr_1_x_O_2_mixed_oxides_Sulfur_resistance_and_regeneration_and_ammonia_formation

BR,

Article NOx storage and reduction properties of Pt/CexZr1− xO2 mixed...