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Average Molecular Structure of Gasoline Engine Combustion Chamber Deposits Obtained by Solid-State 13 C, 31 P, and 1 H Nuclear Magnetic Resonance Spectroscopy
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Abstract
Combustion chamber deposits (CCDs) have been the subject of much research aimed at understanding their role in driveabilty and emissions performance in SI engines. Correlations have been drawn between CCDs and octane requirement increase (ORI). In order to gain a better understanding of the complex structural chemistry of these carbonaceous deposits a large number of these deposits, generated in several SI engines, have been investigated by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. 13C NMR methodologies developed for the study of coal were used to obtain structural and molecular parameters for each of the deposits. These parameters provide an “average molecule” description which defines the average building block of the polymeric backbone of CCDs. These parameters were then correlated with CCD weight and thickness measurements, ORI and cleanliness ratings, and fuel composition. 31P NMR was used to investigate the phosphorus chemistry of oxidized anti-wear agents, originating in the lubricant, which become incorporated into the CCDs. 1H NMR spectral and relaxation data reveals the higher mobility of aliphatic regions of the deposit, with aromatic regions appearing to be motionally restricted, yielding evidence for sample heterogeneity. The overall view that one obtains is that the CCDs are formed via free radical and oxidative product condensation reactions, which polymerize together the heavier aromatic components of the fuel. The degree of polymerization and contraction of the CCD structure towards a “graphite-like” structure is dependent on the fuel used and the severity of the combustive/oxidative environment.
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Edwards, J. and Choate, P., "Average Molecular Structure of Gasoline Engine Combustion Chamber Deposits Obtained by Solid-State 13C, 31P, and 1H Nuclear Magnetic Resonance Spectroscopy," SAE Technical Paper 932811, 1993, https://doi.org/10.4271/932811.Also In
References
- Kalghatgi G.T. “Deposits in Gasoline Engines - A Literature Review,” SAE Paper No. 902105
- Bitting B. Geschwendtner F. Kohlhepp W. Kothe M. Testroet C.J. Ziwica K.H. “Intake Valve Deposits -Fuel Detergency Requirements Revisited,” SAE Paper No. 872117
- Ghetting J.A. “Performance Robbing Aspects of Intake Valve and Port Deposits,” SAE Paper No. 872116
- Benson J.D. ‘Some factors Which Affect Octane Requirement Increase,” SAE Paper No. 750933
- Alquist H.E. Holman G.E. Wimmer D.B. “Some Observations of Factors Affecting ORI,” SAE Paper No. 750932
- Eng K.D. Carlson C.A. Hayden T.E. Sung R.L. “Engine Test Procedures to Evaluate Octane Requirement Increase and Intake System Cleanliness,” SAE Paper No. 892122
- “Chemistry of Combustion Chamber Deposits,” Ebert Lawrence B. Plenum Press New York & London 1985
- Solomon P.R. Fletcher T.H. Pugmire R.J. “Progress in Coal Pyrolysis” Fuel 72 587 1993
- Haenel M.W. “Recent Progress in Coal Structure Research,” Fuel 71 1211 1991
- Solum M.S. Pugmire R.J. Grant D.M. “ 13 C Solid-State NMR of Argonne Premium Coals,” Energy & Fuels 3 187 1989
- Pan V.H Maciel G.E. “The Analysis of Three Representative Premium Coals by 13 C Nuclear Magnetic Resonance” Fuel 72 451 1993
- Bunting B.G. “An Analysis of Intake Valve Deposits From Gasolines Containing Polycyclic Aromatics,” SAE Paper No. 912378
- Megnin M.K. Cobb J.M. Eng K.D. “Development of a Gasoline Additive Screening Test for Intake Valve Stickiness and Deposit Levels” SAE Paper No. 892121
- Pines A. Gibby M.G. Waugh J.S. J. Chem. Phys. 56 1776 1972
- Schaefer J. Stejskal E.O. Buchdahl R. Macromolecules 8 291 1975
- Opella S J. Frey M.H. Amer. J. Chem. Soc. 101 5854 1979
- Murphy P.D. Cassady T.J. Gerstein B.C. Fuel 61 1233 1982
- Mehring M. “High Resolution NMR Spectroscopy in Solids” Diehl P. Fluck E. Kosfeld R. NMR -Basic Principles and Progress 11 Springer Verlag New York 1976
- Botto R.E. Wilson R. Winans R.E. Energy & Fuels 1 173 1987
- Choate P.J. Edwards J.C. “Relationship Between Combustion Chamber Deposits and SI Engine Performance” SAE Paper No. 932812