DFT Prediction of Enhanced Reducibility of Monoclinic Zirconia upon Rhodium Deposition

Doping induced phase stabilization and electronic properties of alkaline earth metal doped zirconium (IV) oxide: A first principles study

The role of divalent dopant cations such as Ca and Mg in phase stabilization of ZrO2 has been demonstrated experimentally, with Mg emerging as a crucial dopant ion because of its ability to enhance the photocatalytic properties of ZrO2. To provide a theoretical basis for these experimental observations, the modifications of the crystal and electronic structure of the monoclinic phase of zirconia, m-ZrO2, upon doping with Mg have been studied at the atomic level using Density Functional Theory method. Additionally, the effect of dopant ionic radius on the electronic properties has been demonstrated by doping with Ca, which is isoelectronic with Mg. On 6.25 % doping, a structural distortion of the monoclinic crystal structure towards a tetragonal structure is observed. Additionally, the Density of States of doped m-ZrO2 exhibits the characteristics of t-ZrO2 in the Zr d orbitals in the unoccupied states and O unoccupied states emerge upon creation of an O vacancy in Mg/Ca doped m-ZrO2. The calculated band gap of m-ZrO2 is 3.6 eV. Upon doping there is a shift of the Fermi energy towards the valence band maximum.

Features of the Catalytic Cracking of Propane with a Step-Wise Change PrxYb2−xZr2O7

In this paper, the features of catalytic cracking of propane with a step-wise change in the composition of the catalyst from Pr2Zr2O7 to Yb2Zr2O7 were considered. For the research, samples of catalysts Pr2Zr2O7, (Pr0.75Yb0.25)2Zr2O7, (Pr0.5Yb0.5)2Zr2O7, (Pr0.25Yb0.75)2Zr2O7 and Yb2Zr2O7 were synthesized and analyzed. Analysis of the results from catalytic experiments showed that for the catalyst (Pr0.25Yb0.75)2Zr2O7, at a temperature of 700 °C, the conversion of propane reaches values of 100%, but for Yb2Zr2O7, this indicator decreases to 84%. The selectivity for ethylene is consistently reduced from 85% to 28% in several catalysts (Pr0.75Yb0.25)2Zr2O7 > Pr2Zr2O7 > (Pr0.5Yb0.5)2Zr2O7 >(Pr0.25Yb0.75)2Zr2O7 > Yb2Zr2O7. An increase in the number of surface adsorption centers leads to a predominant rupture of the C–C bond in the propane molecule with the formation of ethylene. When ytterbium ions are introduced into the catalyst, the amount of ethylene in the reaction products decreases, but the selectivity for propylene increases in the series Pr2Zr2O7 < (Pr0.75Yb0.25)2Zr2O7 < (Pr0.5Yb0.5)2Zr2O7 < Yb2Zr2O7 < (Pr0.25Yb0.75)2Zr2O7, which is associated with a decrease in the binding energy of carbon atoms in propane with the catalytic center during adsorption.

Understanding and controlling the formation of surface anion vacancies for catalytic applications

Systematic computational efforts aimed at calculating surface anion vacancy formation energies as important descriptors of catalytic performance are summarized.

More than a support: the unique role of Nb2O5 in supported metal catalysts for lignin hydrodeoxygenation

How does Nb2O5 in supported catalysts affect the hydrodeoxygenation of lignin? This article discusses the effects of Nb2O5 in detail, including the promotion of C–O bond cleavage, the improvement of water resistance and the enhancement of durability.

Propane dehydrogenation: catalyst development, new chemistry, and emerging technologies

This review describes recent advances in the propane dehydrogenation process in terms of emerging technologies, catalyst development and new chemistry.

First-principles insight into CO hindered agglomeration of Rh and Pt single atoms on m-ZrO2

Kinetic and thermodynamic stability of single-atom and nanocluster catalysts is addressed under reaction conditions within a DFT-parametrised multi-scale thermodynamic framework combining atomistic, non-equilibrium, and nanothermodynamics.