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The Degradation of Hydrocarbons Base Fluids
at Elevated Temperatures
STLE 2006: Calgary 7th- 11th May 2006
Moray S. Stark,* John R. Lindsay Smith, Julian J. Wilkinson
Department of Chemistry, University of York, York YO10 5DD, UK
Department of Chemistry
The Degradation of Hydrocarbons Base Fluids
at Elevated Temperatures
STLE 2006: Calgary 7th- 11th May 2006
Moray S. Stark,* John R. Lindsay Smith, Julian J. Wilkinson
Department of Chemistry, University of York, York YO10 5DD, UK
mss1@york.ac.uk www.york.ac.uk/res/gkg
The Degradation of Hydrocarbons Base Fluids
at Elevated Temperatures
Chemical Mechanisms of Base Fluid Oxidation
Viscosity Modelling of Oxidised Base Fluid
Department of Chemistry
Models of Hydrocarbon Base-Fluids
No. of Carbons
(random example)
XHVI™ 8.2 (average) 39
Department of Chemistry
Models of Hydrocarbon Base-Fluids
No. of Carbons
(random example)
XHVI™ 8.2 (average) 39
Hexadecane 16
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
O
O
.
+ O2
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
O
O
.
+ O2
H
O O
O O
+
.
RH + R
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
O
O
.
+ O2
H
O O
O O
+
.
RH + R
H
O
O O
+ HO
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
O
O
.
+ O2
H
O O
O O
+
.
RH + R
H
O
O O
+ HO
H
O O
+ RH + R
.
Department of Chemistry
Traditional Alkane Oxidation Mechanism
. .
+ ROO + ROOH
O
O
.
+ O2
H
O O
O O
+
.
RH + R
H
O
O O
+ HO
H
O O
+ RH + R
.
H
O
O O
+ H2O
Department of Chemistry
Models of Hydrocarbon Base-Fluids
No. of Carbons
(random example)
XHVI™ 8.2 (average) 39
Hexadecane 16
Department of Chemistry
Models of Hydrocarbon Base-Fluids
No. of Carbons
(random example)
XHVI™ 8.2 (average) 39
Hexadecane 16
Pristane 19
Department of Chemistry
Models of Hydrocarbon Base-Fluids
No. of Carbons
(random example)
XHVI™ 8.2 (average) 39
Hexadecane 16
Pristane 19
Squalane 30
Department of Chemistry
Tertiary Carbons in Base-Fluids
25
20
tertiary C (%)
15
10
5
0
hydrocracked
Group I
isodewaxed
Group II
PAO
Group III
Group III
range
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
25
20
tertiary C (%)
15
10
5
0
Squalane
hydrocracked
Group I
isodewaxed
Group II
Pristane
PAO
Group III
Group III
range
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
Oxidation of Branched Alkanes : GC Analysis
Pristane Oxidation: 1000 mbar O2, 170 ºC, 20 minutes
GC conditions: ZB-5 column, 50-340 ºC, 6 ºC min-1
Product Identification: EI-MS and CI-MS
time (min)
Department of Chemistry
Oxidation of Branched Alkanes : Alcohols
e.g.
OH
{
Department of Chemistry
Oxidation of Pristane : Tertiary Alcohols
OH
OH
Department of Chemistry
Oxidation of Pristane : Secondary Alcohols
e.g.
OH
{
Department of Chemistry
Oxidation Products : Alcohols, Pristan-2-ol
100
Concentration (10 mol dm )
-3
OH
80
-3
60
40
20
0
0 20 40 60 80
Time (min)
Department of Chemistry
Oxidation Products : Alcohols, Pristan-6-ol
100
Concentration (10 mol dm )
-3
OH
80
-3
60 OH
40
20
0
0 20 40 60 80
Time (min)
Department of Chemistry
Oxidation Products : Secondary Alcohols
100
Concentration (10 mol dm )
-3
OH
80
-3
60 OH
40
e.g.
20 OH
0
0 20 40 60 80
Time (min)
Department of Chemistry
Oxidation Products : Ratio of Alcohols
100 tertiary
3. 4
Concentration (10 mol dm )
-3
OH
secondary
80
-3
60 OH
40
e.g.
20 OH
0
0 20 40 60 80
Time (min)
Department of Chemistry
Oxidation Products : Ratio of Alcohols
100 per tertiary H
15
Concentration (10 mol dm )
-3
OH
per secondary H
80
-3
60 OH
40
e.g.
20 OH
0
0 20 40 60 80
Time (min)
Department of Chemistry
Formation of Alcohols
O
O H .
O
Department of Chemistry
Formation of Alcohols
O
O H .
O
+ RH + R.
O. O
H
Department of Chemistry
Formation of Volatile Products
O
O H .
O
+ RH + R.
O. O
H
O + .
O.
Department of Chemistry
Formation of Volatile Products
O
O +
+ RH
Department of Chemistry
Formation of Volatile Products
O
+ O
+ RH
Department of Chemistry
Formation of Volatile Products
O
O + .
+ RH
Department of Chemistry
Oxidation of Branched Alkanes : Pristanones
e.g.
O
{
Department of Chemistry
Formation of Volatile Ketones and Alkanes
40
Concentration (10 mol dm )
-3
30 O
-3
20
10
0
0 20 40 60 80
Time (min)
Department of Chemistry
Formation of Volatile Ketones and Alkanes
40
Concentration (10 mol dm )
-3
30 O
-3
20
10
0
0 20 40 60 80
Time (min)
Department of Chemistry
Formation of Volatile Ketones and Alkanes
40
Concentration (10 mol dm )
-3
30 O
-3
O
+
20
10
0
0 20 40 60 80
Time (min)
Department of Chemistry
Reactions of Alkyl Radicals
+ RH + .
R
.
Department of Chemistry
Reactions of Alkyl Radicals
+ RH + R .
.
+ O2 O
O .
Department of Chemistry
Reactions of Alkyl Radicals
+ RH + R .
.
+ O2 + RH
O
O . O
O
H
Department of Chemistry
Reactions of Alkyl Radicals
+ RH + R .
.
+ O2 + RH
O
O . O
O
H O
H + H2O
Department of Chemistry
Reactions of Alkyl Radicals
+ RH + R .
.
+ O2 + RH
O
O . O
O
H O
H + H2O
O
OH
Department of Chemistry
Formation of Volatiles : Lactones
O O
O O
{
Department of Chemistry
Formation of Volatiles : Lactones
O O
- H2O
O
O O
OH OH
{
Department of Chemistry
Lubricant Viscosity Increase During Use
Paris Taxis
15
Vk100 (cSt)
10
5
Oil Change Oil Change
0
0 10 20 30 40 50 60
Distance (1000 km)
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
120
3.04
100
Viscosity increase (%)
Viscosity (cSt)
80 2.64
60
2.24
40
1.84
20
0 1.44
140 160 180 200 220
Temp ºC
Conditions : Pristane (tetramethylpentadecane) Oxidation in Flow Reactor
Continuous O2 flow, Sampling at 6 minutes, 150 - 210 ºC
Department of Chemistry
Viscosity Modelling : Effect of Polar Products
dodecane - docecanol model mixtures
+
OH
700
600 8
Viscosity (cSt)
Viscosity (%)
500
6
400
300 4
200
2
100
0 0
0 20 40 60 80 100
Alcohol/Alkane (%)
Department of Chemistry
Viscosity Modelling : Effect of Polar Products
dodecane - docecanol model mixtures
+
OH
700
600 8
Viscosity (cSt)
Viscosity (%)
500
6
400
300 4
200
2
100
0 0
0 20 40 60 80 100
Alcohol/Alkane (%)
Department of Chemistry
Viscosity Modelling : Effect of Polar Products
dodecane - docecanol model mixtures
+
OH
110 1.5
Viscosity (cSt)
Viscosity (%)
105
1.4
100
95 1.3
0 2 4 6 8 10
Alcohol/Alkane (%)
Department of Chemistry
Conclusions
Chemical Mechanisms for Formation of
Polar Products
Volatile Products
Viscosity Increase during Lubricant Oxidation
NOT due to Polar Oxidation Products
Future Work
Quantify Polymeric Products
Examine Consequent Viscosity Change
Department of Chemistry
Acknowledgements
University of Leeds Martin Priest, Peter Lee
University of York Trevor Dransfield
Shell Ian Taylor
Infineum Chris Booth, Simon Chung
Financial Support
Shell Global Solutions, Infineum, EPSRC
Moray Stark mss1@york.ac.uk www.york.ac.uk/res/gkg
