680 likes | 919 Views
The Degradation of Lubricants in Gasoline Engines. STLE Annual Meeting : Toronto 17 th - 20 th May 2004. John R. Lindsay Smith, Moray S. Stark, Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest
E N D
The Degradation of Lubricants in Gasoline Engines STLE Annual Meeting : Toronto 17th- 20th May 2004 John R. Lindsay Smith, Moray S. Stark, Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK R. Ian Taylor Shell Global Solutions, Shell Research Ltd., Chester, CH1 3SH, UK Simon Chung Infineum UK Ltd., Milton Hill, Abingdon, Oxfordshire, OX13 6BB, UK
The Degradation of Lubricants in Gasoline Engines Part 3: Chemical Mechanisms for the Oxidation of Branched Alkanes John R. Lindsay Smith,Moray S. Stark, Julian J. Wilkinson* Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK R. Ian Taylor Shell Global Solutions, Chester, CH1 3SH, UK Simon Chung Infineum UK Ltd., Milton Hill, Abingdon, Oxfordshire, OX13 6BB, UK Julian Wilkinson jjw102@york.ac.uk www.york.ac.uk/res/gkg
Aims • Identify products from micro-reactor oxidation. • Compare results to engine. • Use identified products to propose reaction mechanisms. • Ultimately, understand and predict viscosity increase
Chemical Mechanisms for the Oxidation of Branched Alkanes • Previous Work • Branched Alkanes as Base Fluid Models • Chemical Analyses • Reaction Mechanisms
Summary of oxidation ? Viscosity Increase
Traditional Model of Hydrocarbon Oxidation Alkyl radical Alkane
Traditional Model of Hydrocarbon Oxidation Alkane Alkyl radical Hydroperoxy radical
Traditional Model of Hydrocarbon Oxidation Alkane Alkyl radical Hydroperoxy radical Hydroperoxide
Traditional Model of Hydrocarbon Oxidation Hydroperoxide Alkoxy radical
Traditional Model of Hydrocarbon Oxidation Alcohol Alkoxy radical
Traditional Model of Hydrocarbon Oxidation Hydroperoxide Ketone
Ease of abstraction of H atom Primary: Difficult
Ease of abstraction of H atom Primary: Difficult Secondary: Moderately difficult
Ease of abstraction of H atom Primary: Difficult Secondary: Moderately difficult Tertiary: Easy
Ease of abstraction of H atom Primary: Difficult Secondary: Moderately difficult Allylic: Very easy Tertiary: Easy
Models of Hydrocarbon Base-Fluids No. of Carbons XHVI™ 8.2 (average) 39 (random example)
Models of Hydrocarbon Base-Fluids No. of Carbons XHVI™ 8.2 (average) 39 Trimethylheptane 10 (random example)
Trimethylheptane Oxidation : 100 – 120 °C D. E. Van Sickle, J. Org. Chem., 37, 755 1972
Trimethylheptane Oxidation : 100 – 120 °C D. E. Van Sickle, J. Org. Chem., 37, 755 1972
Trimethylheptane Oxidation : 100 – 120 °C D. E. Van Sickle, J. Org. Chem., 37, 755 1972
Models of Hydrocarbon Base-Fluids No. of Carbons XHVI™ 8.2 (average) 39 Trimethylheptane 10 Hexadecane 16 (random example)
Hexadecane Oxidation : 120 – 180 °C Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979
Hexadecane Oxidation : 120 – 180 °C Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979
Hexadecane Oxidation : 120 – 180 °C Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979
Hexadecane Oxidation : 120 – 180 °C Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979
Models of Hydrocarbon Base-Fluids No. of Carbons XHVI™ 8.2 (average) 39 Trimethylheptane 10 Hexadecane 16 Tetramethylpentadecane 19 (random example) (TMPD)
Models of Hydrocarbon Base-Fluids No. of Carbons XHVI™ 8.2 (average) 39 Trimethylheptane 10 Hexadecane 16 TMPD 19 Squalane 30 (random example)
Amount of Tertiary Carbons in a Range of Base Fluids McKenna et al. STLE Annual Meeting, Houston, 2002
Amount of Tertiary Carbons in a Range of Base Fluids McKenna et al. STLE Annual Meeting, Houston, 2002
Oxidation of TMPD Micro-reactor conditions: 1000 mbar O2, 200 ºC, 1 minute GC-MS conditions: ZB-5 column, 50-300 ºC, 6 ºC min-1 time (min) impurity
Oxidation of TMPD: Ketones Ketone (m/e = +14) time (min) impurity
Oxidation of TMPD: Ketones (m/e = +14) time (min)
Oxidation of TMPD: Alkanes Alkane time (min)
Oxidation of TMPD: Fragmentation + RH time (min)
Oxidation of TMPD: Fragmentation + time (min)
Oxidation of TMPD: Fragmentation + time (min)
Oxidation of TMPD: Alkenes time (min)
Possible Mechanisms of Alkene Formation Alcohol Acid Ester
Possible Mechanisms of Alkene Formation Alkene Acid Ester
Alkenes and viscosity increase Dimer (sludge precursor) • Alkenes could cause large viscosity increase.
Oxidation of TMPD: Alcohols Solvent (MeOH) time (min) Conditions: Carbowax column, 50-250 ºC, 4 ºC min-1
Alcohols and viscosity increase Weak interactions Alkanes
Alcohols and viscosity increase Strong interactions (Hydrogen bonding) • Alcohols may cause modest viscosity increase
Oxidation of Squalane Micro-reactor conditions: 1000 mbar O2, 200 ºC, 2 mins GC conditions: ZB-5 column, 50-300 ºC, 6 ºC min-1 Time (mins)
Products of Squalane Oxidation in Micro-Reactor: Ketones Time (mins)