Effect of Potassium on Methanol Steam Reforming on the Cu(111) and Cu(110) Surfaces: A DFT Study

Abstract

The potassium (K) additive is of great importance in improving the efficiency of catalytic reactions in numerous industrial reaction processes. In this work, density functional theory calculations are carried out to investigate the reaction mechanism as well as selectivity and activity of the methanol steam reforming (MSR) reaction on pure and K-added Cu(111) and Cu(110) surfaces. Our results suggest that the K adatom can improve the selectivity of MSR toward CO 2 by stabilizing the weakly adsorbed H 2 CO species and enabling it to react with OH to yield H 2 COOH followed by continuous dehydrogenation into CO 2 and activity of MSR by favoring the rate-limiting steps for H 3 CO, H 2 O, and H 3 COH dehydrogenation. It is found that there are two key factors contributing to K promotion effects: one is the direct K−O bonding interaction that would stabilize nearly all oxygenates including H 2 CO species and the stabilized oxygenates of transition states (TSs) result in the lower dissociation barriers of key steps on both Cu surfaces; the other is the indirect interaction between K and adsorbates mediated by added surface electrons donated by K, which would affect the magnitude of interaction energies between two fragments of TSs and thus energy barriers of key steps. The fact that more electrons are donated from K to Cu(111) than to the Cu(110) surface and further to the TS complexes would result in the stronger promotion effect of K on the MSR reaction over Cu(111) compared with Cu(110). Our results emphasize the essence of the promotion effect of alkali additives on complex reaction systems.

A DFT study on methanol decomposition over single atom Pt/CeO2catalysts: the effect of the position of Pt

“…35,46 And the dominant path on the catalyst model is the same as that on the Pt 1 /CeO 2 catalyst for methanol dehydrogenation (CH 3 OH → CH 3 O* → CO*) by DRIFTS spectroscopy. 45…”

“…35,46 And the dominant path on the catalyst model is the same as that on the Pt 1 /CeO 2 catalyst for methanol dehydrogenation (CH 3 OH -CH 3 O* -CO*) by DRIFTS spectroscopy. 45 The E eff a value is calculated to further evaluate the activity of the catalysts. According to eqn (3), a smaller E eff a value ensures a higher activity.…”

“…In recent years, there have been a lot of experimental and theoretical research studies on the MD reaction mechanism over a variety of catalysts (Ru-based complexes, 37 CeO 2 carriers, [38][39][40] Pt(111), 25,41 Pd(111), Ni(111), 42 Rh(100), 43 Ru(0001), 44 Cu(111), Cu(100), 45 etc.). A comparison of previous work on the mechanism of MD reactions over CeO 2 -supported catalysts is listed in Table S10 (ESI †).…”

DFT Study on Reaction Mechanism of Methanol Steam Reforming on MoS2(100)

“…eV. This energy barrier is smaller than the maximum barrier of the optimal reaction path on Cu(111) [47], and is smaller than that on non-noble metal catalysts such as Cu and Zn[48, 49,47]. Moreover, the by-products that may be produced by the reaction on the surface are carbon, methane, and the reaction path of the by-products is:…”

Unveiling the Origin of Alkali Metal (Na, K, Rb, and Cs) Promotion in CO2 Dissociation over Mo2C Catalysts

“…Alkali metals are very good promoters for CO 2 conversion [ 21 , 22 , 23 ]. For example, CO 2 activation was accelerated in K-modified CuxO/Cu (111) catalysts due to the geometric and electronic effects introduced by K [ 24 ].…”