Computationally Exploring Confinement Effects in the Methane-to-Methanol Conversion Over Iron-Oxo Centers in Zeolites

Abstract

Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to methanol. Here we study this reaction over Fe-oxo sites in the zeolite SSZ-13. By comparing calculations for the fully periodic structure and a cluster for two different methods, the standard van der Waals corrected semi-local density functional PBE-D2 and ACFDT-RPA, a method where correlation is calculated fully non-locally, we find that it is actually the confining environment in the zeolite that reduces the barrier for this reaction by more than 50 % and that the two applied methods lead to qualitatively different results.

Identifying promising metal–organic frameworks for heterogeneous catalysis via high‐throughput periodic density functional theory

“…An appropriate choice of where to artificially terminate the MOF unit cell is often not immediately obvious, and this approach is therefore not amenable to HT screening of MOFs with widely varying topologies. Finite cluster models also inherently introduce artificial boundary effects that have the potential to influence charge delocalization and pore‐based confinement effects . The use of periodic DFT to represent the full crystallographic unit cell naturally resolves these issues, and most implementations of periodic DFT are well‐suited for massively parallel calculations that can be used to treat the larger number of atoms in each simulation.…”

Metal dimer sites in ZSM-5 zeolite for methane-to-methanol conversion from first-principles kinetic modelling: is the [Cu–O–Cu]2+motif relevant for Ni, Co, Fe, Ag, and Au?

“…There have been many attempts to determine the active sites in metal ion-exchanged zeolites. 11,13,[17][18][19][20]22,24,27,28,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] For Cu-exchanged zeolites, a [Cu-O-Cu] 2+ motif has been put forth as a possible candidate for the active site. This complex was identified by a UV-vis spectroscopic signature at around 22 700 cm −1 , and the appearance of this signature correlated with the methane-to-methanol conversion.…”

Homogenous Meets Heterogenous and Electro‐Catalysis: Iron‐Nitrogen Molecular Complexes within Carbon Materials for Catalytic Applications

“…Though strictly speaking not a materials characterisation method, increasingly sophisticated systems increasingly rely on supporting understanding of characterisation techniques by computational modelling. This is none the least relevant for catalytic reactions, including single‐site catalysts, an area that has undergone a tremendous amount of progress thanks to method development, increased computational power . Computationally assessing catalytic activity by relating it to descriptors instead of calculating the activation energies of elementary reaction steps in heterogeneous catalytic reactions has been significantly relying on screening linear free energy relationships (LFERs), or linear scaling relations .…”