Interaction Study of Oxygen and Iron-Sulfur Clusters Based on the Density Functional Theory

Abstract

For the petrochemical industry, the spontaneous burning of iron sulfide compounds has been a major issue. In this study, XRD characterization of samples of iron sulfide compounds with spontaneous combustion tendency revealed that amorphous FeS was the primary constituent of the samples. A molecular simulation was used to build an amorphous FeS cluster model, and the density functional theory was used to examine the adsorption and reactivity characteristics of Fe4S4 clusters with O2. Different adsorption structures are generated by considering different adsorption sites and the electronic characteristics of each adsorption structure are evaluated. The results show that O2 prefers to adsorb around Fe atoms and has repulsion with S atoms, and the adsorption energy is maximum when two O atoms are co-adsorbed around Fe atoms, which is 198.13 kJ/mol. After adsorption charge, oxygen is in the superoxide state. The calculation of the reaction path divides the reaction process into different stages and considers different reaction routes. A thorough evaluation of the energy barriers and reaction energies of the two exothermic reactions leads to the conclusion that reaction path 1 is the optimal reaction path, and the reaction can release a total of 582.76 kJ/mol of heat. According to calculations, dimeric sulfur S2 must absorb a large part amount of energy in order to conduct the oxidation process. However, because S2 is present in the Fe4S4 reaction system, it may start the oxidation reaction by absorbing heat from the system and releasing 470.94 kJ/mol of heat. As a result, we conclude that this spontaneous exothermic reaction is a major cause of iron sulfide compounds spontaneous combustion. The thermal oxidation of the dimeric sulfur S2 generated in the reaction system releases heat that aggregates with the heat from the Fe4S4 cluster’s oxidation reaction system, eventually causing spontaneous combustion as a result of the heat’s continual buildup. In this study, we explore the reason for the extremely easy oxidation and spontaneous burning of iron sulfide compounds from a microscopic perspective to provide a theoretical foundation for the prevention and control of iron sulfide compound spontaneous combustion in the petrochemical sector.

Insight into the Fe atom–FeS cluster synergistic catalysis mechanism for the oxygen evolution reaction in NiS2-based electrocatalysts

“…28,38 Moreover, the NiS 2 (001) slab model was proved to be accurate enough to simulate the surface properties according to the available simulations and experiments, and an 8-atom FeS cluster model was created which determined its structure to be reasonable. [39][40][41][42] The vacuum region of 15 Å was separated to avoid interactions between the periodic images, with periodic slab models of seven layers. In addition, the first Brillouin zone was sampled with a 2 va 2 Â 1 Monkhorst-Pack k-point mesh 43 and the energy cutoff for the plane-wave basis set was 400 eV.…”

Effects of Pyrrhotite on the Combustion Behavior and the Kinetic Mechanism of Pyrite-Pyrrhotite Mixture Powders in the Air

“…Moreover, Fe 1− x S and FeSO 4 were converted to Fe 2 O 3 , resulting in the formation of a large amount of SO 2 and SO 3 at 470-525 °C, which occurred before obtaining the reaction temperature in [43]. Te reaction equations are shown in Equations ( 4) and (5). Te occurrence of diferent phases may be related to the heating rate [50,51].…”

“…Iron sulfde minerals play a key role in geochemistry, marine systems, oil storage and transportation, and environmental management [1][2][3][4][5]. As iron sulfde minerals, pyrite (FeS 2 ) is widely applied to sulfuric acid production, metallurgy, and other industries [6,7], whereas pyrrhotite (Fe 1− x S) has practical application values in biomedicine, magnetic material manufacturing, water treatment, and battery processing, among other felds [8,9].…”

Density Functional Theory Investigation of the Sulfur–Iron Compound Formation Mechanism in Petrochemical Facilities

“…Hydrogen sulfide gas can be dissolved in water and crude oil. Hydrogen sulfide gas may exist in the processes of oil extraction, transportation, processing, and refining. − Petroleum and petrochemical plant facilities and their oxidation products can be corroded by hydrogen sulfide to form iron sulfide compounds. − Iron sulfide compounds can spontaneously combust and release a lot of heat at room temperature in contact with air and then ignite the surrounding combustible materials and induce fire and explosion accidents. − Therefore, the study of the formation mechanism of different sulfur–iron compounds is an important component of the study of the spontaneous combustion of corrosion products in petroleum and petrochemical facilities. The formation process of iron sulfides is very complicated.…”