A DFT Study of the Adsorption and Dissociation of CO on Sulfur-Precovered Fe(100)

Abstract

Sulfur is known to be a poison to several catalytic reactions, e.g., the Fischer-Tropsch synthesis (FTS), in which it affects drastically the performance of both iron- and cobalt-based catalysts. However, despite the importance of this industrial process, little is known about what elementary steps are poisoned by sulfur. In the present article, we report, using density functional theory, the effect of sulfur on one of the most relevant reactions in the FTS: the dissociation of carbon monoxide over iron surfaces. We have studied the adsorption and dissociation of CO on Fe(100)-S-p(2 x 2) (theta(S) = 0.25 ML) and on Fe(100)-S-c(2 x 2) (theta(S) = 0.50 ML). We have found surface configurations that correlate well with the desorption features observed in temperature-programmed desorption mass spectroscopy. In addition, we have calculated the activation energy of CO dissociation on Fe(100)-S-p(2 x 2), which, interestingly, is very similar to the activation energy of CO dissociation on the sulfur-free Fe(100) surface. However, the sign of the reaction changes by the presence of sulfur; CO dissociation is highly exothermic on the sulfur-free Fe(100) surface, whereas on the Fe(100)-S-p(2 x 2) surface, it is slightly endothermic. Moreover, according to our results, the influence of sulfur in the CO dissociation seems to be short-ranged.

Quantum chemical and experimental investigations on inhibitory behavior of amino–imino tautomeric equilibrium of 2-aminobenzothiazole on steel corrosion in H2SO4 solution

“…8B). The resulting Fe-(N15 5C15 5N2) h 3 -type bond distances (2.26-2.30 Å ) confirm the presence of chemisorption with metal as the bond distances are within the reported range (2.00-2.90 Å ) [59][60][61]. The mechanism of inhibitor interaction with metal can be explained on the basis of the frontier orbital studies, and all low lying HOMO orbitals are a resultant derivative of the combination of orbitals of the metal with the inhibitor.…”

A Density Functional Theory Study on the Effect of Zero‐Point Energy Corrections on the Methanation Profile on Fe(100)

“…The relative positions of the metal atoms were fixed initially as those in the bulk, with an optimized lattice parameter of 2.8313 (the experimental value is 2.8665 ). [22,23] The reciprocal space of the p(22) unit cell was sampled with a (551) k-point grid automatically generated by using the Monkhorst-Pack method. [13] The calculated magnetic moment of bcc iron at the equilibrium lattice constant was 2.16 m B , in good agreement with the experimental value of 2.22 m B .…”

The Surface Chemistry of Water on Fe(100): A Density Functional Theory Study

“…[36] Oxygen is located 1.56 above the Fe surface at the top site, 1.39 above the bridge site and 0.67 above the hollow. [1][2][3][4][5][12][13][14][15][16][17] Interestingly, the vibrational frequencies (Table 1) identify all three adsorption sites as local minima on the potential energy surface. [4,15,17] Sulphur was found to be less strongly bound to the surface with an adsorption energy of À6.00 eV, also preferring the four-fold hollow site (z S = 1.03 ).…”