Role of the Zn atomic arrangements in enhancing the activity and stability of the kinked Cu(2 1 1) site in CH3OH production by CO2 hydrogenation and dissociation: First-principles microkinetic modeling study

Title
Role of the Zn atomic arrangements in enhancing the activity and stability of the kinked Cu(2 1 1) site in CH3OH production by CO2 hydrogenation and dissociation: First-principles microkinetic modeling study
Authors
함형철조덕연이민우이관영
Keywords
DFT; CH3OH; Cu-Zn
Issue Date
2019-05
Publisher
Journal of catalysis
Citation
VOL 373-350
Abstract
In this work, we unravel the beneficial role of the Zn ensemble (in particular, an a single Zn atom) in the sixfold-coordinated kinked (Cu-vacant) site of the stepped Cu(2  1  1) surface for enhancing the reactivity and durability of catalyst in the CH3OH production from CO2 and H2. For such purpose, by using the density functional theory (DFT) and microkinetic modeling methods, we systematically calculate the catalytic properties (activation energy barrier, turn of frequency (TOF), and rate constant), physical properties (cohesive and formation energy) and electronic structures (local density of state, and local charge distribution) of the different defective Cu sites [such as the stepped, kinked, Zn-substituted stepped Cu(2  1) surfaces] and the different Zn ensembles [dimer, and linear ensemble]. First, our DFT calculations exhibit that the Zn atoms at the sevenfold-coordinated site of the Cu(2  1) surface tend to be isolated and acts as the modifier to suppress the loss of Cu atoms from the stepped Cu(2  1) surface. Second, we find that the catalysis of CH3OH synthesis strongly depends on the type of defects at the Cu(2  1) surface. In particular, the single Zn atom-substituted (sevenfold-coordinated) stepped site in the Cu(2  1) surface is found to have the superior catalytic activity (TOF  =  3.07  ×  10− 5  s− 1 @ P  75  bar and T  523  K) toward the CH3OH formation compared to the traditionally-known active Cu(2  1) surface (TOF  2.73  7  1). In contrast, the sixfold-coordinated kinked site is determined to largely slow down the rate of CH3OH production (TOF  3.34  15  1). The increased catalysis in the Zn-associated stepped site is related to the signi
URI
http://pubs.kist.re.kr/handle/201004/69324
ISSN
0021-9517
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