Kiw Yu Min, Adam Pierre, Schaeffer Philippe, Thiébaut Benoît, Boyer Chantal, Obrecht Nicolas
University of Strasbourg, CNRS, Institut de Chimie de Strasbourg UMR 7177 F-67000 Strasbourg France
TotalEnergies Solaize Research Center BP22-69360 Cedex France.
RSC Adv. 2022 Aug 16;12(36):23083-23090. doi: 10.1039/d2ra03036e.
During engine tests, it has been observed that the combined use of molybdenum dithiocarbamates (MoDTC) and methylene-(dithiocarbamates) (MBDTC) in formulated engine oils resulted in better fuel efficiency, keeping the friction coefficient stable at low values for a longer period of time as compared to the same oil devoid of MBDTC. Therefore, the interactions between MBDTC and MoDTC have been investigated at the molecular level. The qualitative and quantitative evolution of MoDTC in two engine oils similarly formulated, but with and without MBDTC, were compared during engine tests using a specifically developed high performance liquid chromatography-mass spectrometry (HPLC-MS) analytical method. Parallel to the molecular study, the evolution of the friction coefficients of both lubricants as well as the evolution of the fuel consumption of the engine were determined. The combined use of MoDTC and MBDTC was shown to exhibit better fuel efficiency and to maintain a relatively low friction coefficient for longer periods of time as compared to the oil devoid of MBDTC. It could be determined that the enhanced performances observed were presumably related to an extension of the lifetime of MoDTC in the engine oil containing MBDTC. Since the MoDTC remaining at the end of the engine test in oil containing MBDTC exclusively bear ligands corresponding to the dithiocarbamate moieties of MBDTC, it can be concluded that the prolonged existence of MoDTC was due to the progressive replacement of the degraded dithiocarbamate ligands on MoDTC educts by those released from MBDTC during engine functioning. As a result, the concentrations of MoDTC could be maintained at a useful level for a longer period in the engine oil containing MBDTC, leading to better fuel consumption performances.
在发动机测试期间，人们观察到，在调配的发动机油中同时使用二硫代氨基甲酸钼（MoDTC）和亚甲基二硫代氨基甲酸盐（MBDTC）可提高燃油效率，与不含MBDTC的同一种油相比，能使摩擦系数在较低值保持更长时间的稳定。因此，已在分子层面研究了MBDTC与MoDTC之间的相互作用。在发动机测试期间，使用专门开发的高效液相色谱-质谱联用（HPLC-MS）分析方法，比较了两种配方相似但分别含有和不含MBDTC的发动机油中MoDTC的定性和定量变化。在进行分子研究的同时，还测定了两种润滑剂的摩擦系数变化以及发动机的燃油消耗变化。结果表明，与不含MBDTC的油相比，MoDTC和MBDTC同时使用表现出更好的燃油效率，并且能在更长时间内保持相对较低的摩擦系数。可以确定，观察到的性能提升可能与含MBDTC的发动机油中MoDTC的寿命延长有关。由于在发动机测试结束时，仅含MBDTC的油中剩余的MoDTC仅带有与MBDTC的二硫代氨基甲酸酯部分相对应的配体，因此可以得出结论，MoDTC的存在时间延长是由于在发动机运行过程中，MBDTC释放的配体逐渐取代了MoDTC反应物上降解的二硫代氨基甲酸酯配体。结果，在含MBDTC的发动机油中，MoDTC的浓度可以在更长时间内保持在有效水平，从而带来更好的燃油消耗性能。
