Radiospectroscopic Study of Used Marine Oils

This work investigated the hydrocarbon degradation and depletion of the anti-wear additive zinc dialkyldithiophosphate (ZDDP) in several used marine motor oils using high-resolution nuclear magnetic resonance (NMR). The article presents research results showing that during engine operation a number of characteristics of motor oil change: degree of aromaticity, ratio of methyl/methylene groups, and composition of phosphorus-containing additives. The possibility of determining oil using the NMR spectrum lines of antiwear additives has been demonstrated. For anti-wear additives containing phosphorus, such as ZDDP and molybdenum dialkyldithiophosphate (MoDDP), ³¹P NMR has been found to provide both depletion rates and insight into the wear mechanism of the additives. The high efficiency of using the high-field NMR spectroscopy method for studying fresh and destruction of used marine motor oils has been demonstrated. ¹H, ¹³C and ³¹P NMR studies show the presence of changes in motor oil caused by the accumulation of products of its decomposition, degradation and decomposition of additives during engine operation. The ability of the NMR radiospectroscopy method to monitor additive depletion is analyzed, which is apparently one of the most difficult problems in used oil analysis. A characteristic feature of the NMR spectra of all used oils is line broadening caused by the presence of metal wear particles. It is characteristic that the broadening of the 13C NMR lines for waste oils is significantly less than the lines broadening in the NMR spectra of protons. In the 13C NMR spectrum of used oil, an increase in the intensity of the line from aromatic hydrocarbons is observed, i.e. as the degree of oil degradation increases, the content of aromatic compounds increases. The results of the study of fresh and used motor oils obtained in this work are new. They can be used to create a system for monitoring the quality of motor oils and for diagnosing engine malfunctions using used oil.

1. Edwards J. Applications of NMR Spectroscopy in Petroleum Chemistry // A Review of Applications of NMR Spectroscopy in the Petroleum Industry, Chapter 16 in “Spectroscopic Analysis of Petroleum Products and Lubricants”. — ASTM International. — 2011

2. Barnes A.M., Bartle K.D., and Thibon V.R.A. A Review of Zinc Dialkyldithiophosphates (ZDDPS): Characterisation and Role in the Lubricating Oil // Tribology International. — 2001 (34), 389—395

3. Hosonuma K., Yoshida K., and Matsunaga A. The Decomposition Products of Zinc Dialkyldithiophosphate in an Engine and Their Interaction with Diesel Soot // Wear. — 1985 (103), 297—309

4. Fuentes F., Heidema J., Ramasamy S., and Williams S. 31P NMR Analysis of Thermal Decomposition of Tributylmethylphosphonium Dimethylphosphate // Journal of Undergraduate Chemistry Research. — 2022 (21), no. 3, 81—83

5. Kiw Y.M., Schaeffer P., Adam P., etc. Ligand Exchange Processes between Molybdenum and Zinc Additives in Lubricants: Evidence from NMR (1H, 13C, 31P) and HPLC-MS Analysis // RSC Adv. — 2020 (10), 37962—37973

6. Greenall A., Neville A., Morina A., and Sutton M. Investigation of the Interactions between a Novel, Organic Anti-Wear Additive, ZDDP and Overbased Calcium Sulphonate // Tribology International. — 2012 (46), 52—61

7. Li Y.-R., Pereira G., Kasrai M., and Norton P.R. Studies on ZDDP Anti-Wear Films Formed Under Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR // Tribol. Lett. — 2007 (28), 319—328

8. Koryakina B.B., Shits E.Yu., Sedalishchev I.I. Eksperimental'nyj analiz resursa srabatyvaniya motornych masel dizel'nych dvigateley metodom NMR-spektroskopii vysokogo razresheniya // Khimiya v interesakh ustoychivogo razvitiya. — 2014, no. 5, 469—475 (in Russian)

9. Ferguson S., Johnson J., Gonzales D., etc. Analysis of ZDDP Content and Thermal Decomposition in Motor Oils Using NAA and NMR // Physics Procedia. — 2015 (66), 439—444

10. Sarpal A.S., Christopher J., Mukherjee S., etc. Study of Additive-Additive Interactions in a Lubricant System by NMR, ESCA, and Thermal Techniques // Lubrication Science. — 2005 (17), 319—345

11. Parekh K., Chen X., and Aswath P.B. Synthesis of Fluorinated ZDDP Compounds // Tribol. Lett. — 2009 (34), 141—153

12. Sinyavsky N. and Mershiev I. NMR Relaxometry Used Ship Oils // Journal of Eta Maritime Science. — 2022 (10), no. 3, 195—201

13. Wooton D. Using Nuclear Magnetic Resonance to Track Additive Depletion, Wooton Consulting; Dave Wooton, Noria Corporation, https://www.machinerylubrication.com/Read/764/nuclear-magnetic-resonance-additive

14. Marshall G.L. Characterization of Lubricants Using 31P Fourier Transform Nuclear Magnetic Resonance Spectroscopy // Applied Spectroscopy. — 1984 (38), no. 4, 522—526

15. Wolak A., Molenda J., Zając G., and Janocha P. Identifying and Modelling Changes in Chemical Properties of Engine Oils by Use of Infrared Spectroscopy // Measurement. — 2021 (186), 110141