Moray S. Stark,* John R. Lindsay Smith, Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK STLE 2006: Calgary 7 th - 11 th May 2006 The Degradation of Hydrocarbons Base Fluids at Elevated Temperatures Department of Chemistry

Moray S. Stark,* John R. Lindsay Smith, Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK STLE 2006: Calgary 7 th - 11 th May 2006 The Degradation of Hydrocarbons Base Fluids at Elevated Temperatures

 Chemical Mechanisms of Base Fluid Oxidation  Viscosity Modelling of Oxidised Base Fluid Department of Chemistry The Degradation of Hydrocarbons Base Fluids at Elevated Temperatures

No. of Carbons XHVI™ 8.2 (average) 39 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

Traditional Alkane Oxidation Mechanism

Department of Chemistry Traditional Alkane Oxidation Mechanism

Department of Chemistry Traditional Alkane Oxidation Mechanism

Department of Chemistry Traditional Alkane Oxidation Mechanism

Department of Chemistry Traditional Alkane Oxidation Mechanism

Department of Chemistry Traditional Alkane Oxidation Mechanism

No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 Pristane 19 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 Pristane 19 Squalane30 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

Tertiary Carbons in Base-Fluids S. McKenna, M. Casserino, K. Ratliff, Comparing the Tertiary Carbon Content of PAO’s and Mineral Oils Presentation, STLE Annual Meeting, Houston, 2002

Tertiary Carbons in Base-Fluids S. McKenna, M. Casserino, K. Ratliff, Comparing the Tertiary Carbon Content of PAOs and Mineral Oils Presentation, STLE Annual Meeting, Houston, 2002

Bench-Top Reactors Department of Chemistry

time (min) Department of Chemistry Oxidation of Branched Alkanes : GC Analysis Pristane Oxidation: 1000 mbar O 2, 170 ºC, 20 minutes GC conditions: ZB-5 column, ºC, 6 ºC min -1 Product Identification: EI-MS and CI-MS

Department of Chemistry Oxidation of Branched Alkanes : Alcohols { e.g.

Department of Chemistry Oxidation of Pristane : Tertiary Alcohols

Department of Chemistry Oxidation of Pristane : Secondary Alcohols e.g. {

Department of Chemistry Oxidation Products : Alcohols, Pristan-2-ol

Department of Chemistry Oxidation Products : Alcohols, Pristan-6-ol

Department of Chemistry Oxidation Products : Secondary Alcohols e.g.

Department of Chemistry Oxidation Products : Ratio of Alcohols e.g.

Department of Chemistry Oxidation Products : Ratio of Alcohols e.g.

Department of Chemistry Formation of Alcohols

Department of Chemistry Formation of Alcohols

Department of Chemistry Formation of Volatile Products

Department of Chemistry Formation of Volatile Products + + RH

Department of Chemistry Formation of Volatile Products + + RH

+ Department of Chemistry Formation of Volatile Products + RH

Department of Chemistry Oxidation of Branched Alkanes : Pristanones e.g. {

Department of Chemistry Formation of Volatile Ketones and Alkanes

Department of Chemistry Formation of Volatile Ketones and Alkanes

Department of Chemistry Formation of Volatile Ketones and Alkanes +

Department of Chemistry Reactions of Alkyl Radicals

Department of Chemistry Reactions of Alkyl Radicals

Department of Chemistry Reactions of Alkyl Radicals

Department of Chemistry Reactions of Alkyl Radicals

Department of Chemistry Reactions of Alkyl Radicals

Department of Chemistry Formation of Volatiles : Lactones {

Department of Chemistry Formation of Volatiles : Lactones {

Paris Taxis Lubricant Viscosity Increase During Use Department of Chemistry

Viscosity Increase due to Lubricant Degradation Due to Formation of:  Polar Products Alcohols, Carboxylic Acids, etc.  Polymeric Products Dimers, Trimers, etc. of Base Fluid  Insoluble Products Aggregating Particles e.g. Soot, Micelles of Highly Polar Products Department of Chemistry

Viscosity Increase due to Lubricant Degradation Department of Chemistry Conditions : Pristane (tetramethylpentadecane) Oxidation in Flow Reactor Continuous O 2 flow, Sampling at 6 minutes, ºC

Viscosity Modelling : Effect of Polar Products  dodecane - docecanol model mixtures Department of Chemistry +

Viscosity Modelling : Effect of Polar Products  dodecane - docecanol model mixtures Department of Chemistry +

Viscosity Modelling : Effect of Polar Products  dodecane - docecanol model mixtures Department of Chemistry +

Viscosity Modelling : Effect of Polar Products  dodecane – carboxylic acid model mixtures  1:1 propanpoic acid: nonanoic acid Department of Chemistry

Viscosity Modelling : Effect of Polar Products  dodecane – carboxylic acid model mixtures  1:1 propanpoic acid: nonanoic acid Department of Chemistry

Viscosity Modelling : Effect of Polar Products Department of Chemistry  dodecane – carboxylic acid model mixtures  1:1 propanpoic acid: nonanoic acid

Conclusions  Chemical Mechanisms for Formation of  Polar Products  Volatile Products  Viscosity Increase during Lubricant Oxidation NOT due to Polar Oxidation Products Department of Chemistry Future Work  Quantify Polymeric Products  Examine Consequent Viscosity Change

Acknowledgements University of LeedsMartin Priest, Peter Lee University of YorkTrevor Dransfield ShellIan Taylor InfineumChris Booth, Simon Chung Financial Support Shell Global Solutions, Infineum, EPSRC Moray Stark

The Degradation of Hydrocarbons Base Fluids at Elevated Temperatures (Abstract for STLE 2006: Calgary 7th- 11th May 2006) The Degradation of Hydrocarbons Base Fluids at Elevated Temperatures (Abstract for Talk for STLE Annual Conference, Calgary, May 2006) Moray S. Stark*, John R. Lindsay Smith, Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK To help with the design of the next generation of lubricants, it is necessary to understand how they degrade during use as this partly determines their useful lifetime. As part of a wider study of this phenomenon, the degradation of structurally simpler analogues of hydrocarbon base fluids (branched alkanes squalane, C 30 H 62 and pristine, C 19 H 40 ) has been investigated under controlled laboratory conditions at temperatures representing sump to piston temperatures (100 to 230 C), and this work is reported here. Degradation products have been identified by GC-MS and quantified by GC and FTIR, with chemical mechanisms proposed to account for the formation of products such as carboxylic acids, alcohols, ketones and alkenes, mostly formed via radical attack on tertiary hydrogen atoms. The viscosity change occurring during the oxidation of these model base fluids has also been examined and work is reported on trying to identify which products cause the viscosity change observed. * Biography for Presenting Author The presenting author has a BSc and PhD in Physics, but has been working as a Chemist for longer than he can remember. The past few years have been spent specialising in the study of the oxidation mechanisms of hydrocarbon and ester lubricant base fluids and the effects that oxidation has on the rheology of lubricants.