Role of lattice oxygen in methane activation on Ni-phyllosilicate@Ce1-xZrxO2 core-shell catalyst for methane dry reforming: Zr doping effect, mechanism, and kinetic study

Sandwich structured core-shell Ni-Phyllosilicate@Ce1-xZrxO2 catalysts with high coke resistance and activity are reported for DRM. Optimal Zr loading (x = 0.05 +/- 0.1) in the Ce1-xZrxO2 shell is observed to significantly increase the intrinsic activity for DRM. Extensive catalyst characterization using HRTEM, XRD, TPR, O-2-TPD, XPS, EXAFS and CO pulse chemisorption indicates that the enhancement in DRM activity upon Zr doping can be attributed to the increase in lattice oxygen mobility of the ceria-zirconia shell and stronger metal-support interaction with Ni. It is inferred from a rigorous kinetic and mechanism study that the lattice oxygen of Ce1-xZrxO2 not only participates in the oxidation of carbonaceous reaction intermediates but also facilitates the rate determining step of C-H bond dissociation of CH4 on Ni by an oxygen-mediated dissociation pathway. The involvement of lattice oxygen in methane activation and dissociation manifests in the higher DRM activity of the Zr-doped catalyst with maximum oxygen storage capacity.

Automated summary

Sandwich structured core-shell Ni-Phyllosilicate@Ce1-xZrxO2 catalysts with optimal Zr loading in the Ce1-xZrxO2 shell are found to greatly enhance the intrinsic activity for DRM due to increased lattice oxygen mobility of the ceria-zirconia shell and stronger metal-support interaction with Ni. Involvement of lattice oxygen in methane activation and dissociation contributes to the higher DRM activity of the Zr-doped catalyst with maximum oxygen storage capacity, as inferred from rigorous kinetic and mechanism studies.