A Theoretical Investigation on the Dynamic Behavior of Molybdenum Dithiocarbamate Molecule in the Engine Oil Phase

Abstract

We investigated the decomposition reaction mechanism of a molybdenum dithiocarbamate (MoDTC) molecule using computational chemistry methods: density functional theory and hybrid quantum chemical/classical molecular dynamics methods. The density functional theory results showed that the linkage isomerization reaction of the MoDTC preferentially takes place than its direct decomposition reaction. During a hybrid quantum chemical/classical molecular dynamics simulation, the linkage isomer of MoDTC was observed and subsequently bond weakening of its MoO was also observed in the polyalphaolefine phase. From these results, we proposed a new decomposition reaction pathway of the MoDTC molecule: it first forms its linkage isomer as the intermediate in the engine oil phase then decomposes into molybdenum disulfide and monothiocarbamic acid molecules on the rubbing nascent surfaces.

Tribocatalytic behaviour of a TiO2 atmospheric plasma spray (APS) coating in the presence of the friction modifier MoDTC: a parametric study

“…7 For the reduction reaction of MoDTC to occur (from Mo +V to Mo +IV), a reducing agent seems to be needed in the form of negatively charged particles (ions, electrons, free radicals) or additives (electron donor). 11,14 The change in the oxidation state of Mo is also needed in order to lower the energy barriers leading to a linkage isomer of the MoDTC that has been identied as a good candidate to be easily decomposed to MoS 2 . We theoretically studied a possible reaction pathway for reduction of MoDTC to the linkage isomer (LI MoDTC).…”

Nano-MoS2 and Graphene Additives in Oil for Tribological Applications

“…Variation of friction coefficient with the oxygen concentration in the film[42].Onodera et al[43] drew similar conclusions by simulating single sheet MoS 2 lubrication with computational chemistry methods. They proposed that the excellent tribological properties of MoS 2 sheets was attributed to the increase of coulombic repulsion energies between the two sulphur layers reacting with the iron surfaces as shown in the Fig.…”

Molecular evidence for sulfurization of molybdenum dithiocarbamates (MoDTC) by zinc dithiophosphates: a key process in their synergetic interactions and the enhanced preservation of MoDTC in formulated lubricants?

“…Step II of this mechanism presents some analogies with the rearrangement reaction proposed by several authors to play a role in the tribochemical formation of MoS 2 from MoDTC or in the thermo-oxidative degradation of MoDTC. 27,49,50 It involves an exchange between a sulfur atom from the ligand and an oxygen atom on the MoDTC core. Another possible mode of formation of 2S-MoDTC could be the sulfurization of MoDTC by H 2 S resulting from the thermal decomposition of ZnDTP complexes described by Dickert and Rowe (1967) 51 and Spikes (2004).…”