Role of Surface Species Interactions in Identifying the Reaction Mechanism of Methanol Synthesis from CO₂Hydrogenation over Intermetallic PdIn(310) Steps

Abstract

Considerable attention has been paid to the development of new catalysts for methanol synthesis from CO 2 hydrogenation for a long period of time. The PdIn intermetallic catalyst was found recently to exhibit good stability and activity for methanol formation. We thus performed a theoretical study to understand the reaction mechanism of methanol synthesis on stepped PdIn(310), combining density functional theory (DFT) calculations and microkinetic analysis. On the basis of energetics obtained on clean PdIn(310), we found that the preferred reaction pathway for CH 3 OH generation proceeds through the COOH intermediate and further CO hydrogenation. However, microkinetic results suggested that the coverage of formate and carbon monoxide at the steady state is nearly one monolayer at the corresponding preferred adsorption site, that is, the In site for HCOO and the Pd site for CO, within the whole temperature range studied. Therefore, further studies were carried out to reveal the influence of coverage of preadsorbed formate and carbon monoxide on adsorption energies. It turned out that the differential adsorption energy of formate at the In site is comparable to that at the Pd site when the surface is covered by two formate at the In step-bridge site, indicating that it is possible for an additional formate to adsorb at either the Pd or In site under such condition. On this basis, we found with further DFT calculations and microkinetic analysis that the preferred reaction mechanism of methanol formation would change to the one including the HCOOH intermediate and the reaction prefers to happen at the Pd site, with two formate preadsorbing at the In step-bridge site at the same time. It was found that such changes can be attributed to the reduced barriers of elementary steps in this path introduced by the formate coverage effect. Therefore, it is imperative to carry out a theoretical study for surface reactions by combining DFT calculations and microkinetic analysis and to take the interactions between dominant surface species into account when identifying the mechanism under reaction conditions.

Theoretical Insights into the Formation Mechanism of Methane, Ethylene and Methanol in Fischer‐Tropsch Synthesis at Co2C Surfaces

“…This would result in the suppression of the competition between the methane and ethylene. That is why, we would have to include adsorbate‐adsorbate interactions in future studies on the selectivity of different reactions over Co 2 C, and approaches developed recently by our group can be used [16c,d,27] . For example, while we find that CO might be dominant on these surfaces at the steady‐state, further calculations of the energies of adsorbates and transition states would be performed in the presence of CO molecules on the surface, and MKM studies will also be carried out with these energies.…”

First-Principles-Based Microkinetic Modeling of Methane Steam Reforming with Improved Description of Product Desorption

“…33,34 BEEF-vdW, namely Bayesian error estimation functional with van der Waals correlation, 35 has extensive applications in computational surface catalysis studies. [3][4][5][7][8][9][10]36 The electron−ion interaction was described with the projected augmented wave (PAW) method. 37 The electronic plane-wave energy cutoff was set as 500 eV.…”

“…All the DFT calculations in this work were performed with the Vienna Ab-initio Simulation Package (VASP) , code using the BEEF-vdW exchange-correlation functional. , BEEF-vdW, namely Bayesian error estimation functional with van der Waals correlation, has extensive applications in computational surface catalysis studies. − ,− , The electron–ion interaction was described with the projected augmented wave (PAW) method . The electronic plane-wave energy cutoff was set as 500 eV.…”

Insights into the adsorption/desorption of CO2 and CO on single-atom Fe-nitrogen-graphene catalyst under electrochemical environment

“…Electrocatalytic CO 2 reduction reaction (CO 2 RR) is an attractive process to mitigate the greenhouse effect. This process can achieve zero-emission of pollutants and produce energy-dense fuels or value-added products, thus triggering broad interest and intensive research over it [1][2][3][4][5][6][7][8][9][10] . However, the application of CO 2 RR is limited by the low efficiency and high cost of using transitional metal as electrocatalysts.…”