phosphorus emission index (pei) studies of zddp in engine oils escit meeting, 2006 august 8 at...

Phosphorus Emission Index (PEI) Studies Of ZDDP in Engine Oils

ESCIT Meeting, 2006 August 8At Toyota Technical Center

Ann Arbor, Michigan

Presented by: Ted Selby, Savant, Inc.

PEI as a measure of phosphorus volatility and catalyst response

Background of Present WorkThe PEI technique was developed from analysis of the volatiles from engine oils containing ZDDP using an instrument developed by Savant Labs and designed by the Tannas Co.

Temperature Sensorand Controller

Test Oil

Air Inlet

Vacuum Monitor

Noble MetalHeater & Insulation

Volatiles

Collection Vessel

Reaction FlaskTop & Bottom

Vacuum

Filter & Drain

Temperature Sensorand Controller

Test Oil

Air Inlet

Vacuum Monitor

Noble MetalHeater & Insulation

Volatiles

Collection Vessel

Reaction FlaskTop & Bottom

Vacuum

Filter & Drain

Background of Present Work (cont.)

1. Volatility of the engine oil in the Noack test, or

Using data from the Institute of Materials database on several thousand engine oils, it was found that there was no correlation between phosphorus volatility and

In first studies, the PEI protocol was applied for one hour at 250°C (approximately ring belt temperatures).

The Phosphorus Emission Index or PEI is a measure of phosphorus volatility from engine oil in milligrams/Liter.

2. Initial concentration of phosphorus

PEI = mgP / Loil


Following these initial studies, the question was raised by Ford Motor Co. as to whether PEI250 would correlate with catalyst deposition and exhaust gas characteristics.

Limited information from taxi fleet tests by Ford and Afton Chemical Co. showed such correlation ….




Correlation of PEIs of Three Fresh Taxi Fleet Engine Oils With Grams of Phosphorus on Catalyst

0

10

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30

40

50

0 5 10 15 20 25 30

Phosphorus on Catalysts, g

Ph

osp

ho

rus E

mis

sio

n I

nd

ex RO-133 (None)

RO-136 (Ca)RO-132 (Ca/Mg)

Expected Correlation

Correlation was based on four values and also showed effects of other additives in the oils ….

…. as well as the effects on emissions ….


Background of Present Work (cont.) Correlation of PEI with NOx / Mile.

Phosphorus Emission Index Of Fresh Taxi Oils vs. NOx/Mile

0

10

20

30

40

50

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

NOx/Mile, grams

Ph

osp

ho

rus

Em

issi

on

In

dex


Following these initial studies, the question was raised by Ford Motor Co. as to whether the PEI would correlate with catalyst deposition and exhaust gas characteristics.

More recently, cooperative work between the Savant Labs and ICL-PPLP has also shown information on the mechanism of ZDDP decomposition particularly for ….

Limited information from taxi fleet tests by Ford and Afton Chemical Co. showed such correlation.



Background of Present Work (cont.) 1. Different ZDDP chemistries using PEI250

Effect of Exposure Time on PEIs of Two ZDDPs In Modified Selby-Noack Tests

0

5

10

15

20

0 10 20 30 40 50 60

Exposure Time, min.

PE

I, m

g/L

Primary Alcohol ZDDP

Secondary Alcohol ZDDP


Background of Present Work (cont.) 2. Different temperatures (one hour exposure time)


Change in PEI Values with Temperature

0

20

40

60

80

100

150 175 200 225 250

Temperature, °C

PE

I, m

g/L

Oil 1 (SL, GF3, SAE 10W-30)

Oil 3 (SJ, CH4, SAE 10W-30)

Background of Present Work (cont.) 3. Different exposure time at a given temperature.


Effect of Exposure Time on PEI at 165°C For Oils 1 and 3 (up to 48 Hours)

0

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40

60

80

100

120

0 10 20 30 40 50 60

Exposure Time, hours

PE

I, m

g/L

Oil 1 SAE 10W-30 (GF3, API SL)

Oil 3 SAE 10W-30 (API SJ, CH4)

250°C equivalence250°C equivalence

On the basis of the foregoing time exposure work, PEI165 values were determined at 16 hours using a co-volatile SN75 base oil and this became an experimental protocol.

However, to meet any questions regarding this approach, PEI165-16 values of two GF-4 engine oils were determined with and without use of a co-volatile.

Recent Work

Results confirmed expectations that a co-volatile would not influence the value of PEI165-16 obtained ….


Since past information gathered with PEI250 had shown literally no correlation with base oil volatility, it was considered that the use of a co-volatile should not influence the volatilization of phosphorus.

Recent Work (cont.) No significant effect of a co-volatile on PEI165 values.


CD

PEI@250°C,1h, no diluent

PEI@165°C,16h, diluent in sample

PEI@165°C,16h, no diluent insample

PEI@165°C,16h, no diluent insample - repeat analysis

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60

Oils

PEI values

Study of PEI165, With and Without Co-Volatile SN75

26

52

28

25

8

13

5455

Lack of correlation between phosphorus content of the engine oil and phosphorus volatility was shown by a bench test (PEI250) which, in contrast, showed interesting correlation with catalyst deposition of limited field tests. Later, studies of different types of ZDDP showed clear differences between their decomposition mechanisms.

Summary of Background

More data was requested in applying this test method to engine, catalyst, and emission studies to further develop correlation and understanding of the causes and control of phosphorus volatility using engine operating temperatures.


Versatility of the PEI method permitted extending these studies to other temperatures and volatilization exposure intervals with the result that other characteristics of phosphorus volatility became evident using NMR methods.

As temperature is reduced at which information is sought from the PEI protocol, more attention must be paid to the assurance of gathering sufficient sample in the instrument’s Collector.

Considerable interest has developed in applying higher and lower PEI temperatures, especially in the normal to hard engine operating range. For the lower range, a PEI120 protocol was very recently developed and applied.

Present Work

For such lower temperature, it was anticipated that a fairly light hydrocarbon co-volatile would be required and analytical-grade kerosene was chosen.


Present Work (cont.)

It was thought to be of value to apply an extended 48-hour, 120°C technique (PEI120-48) that would provide opportunity to gain more information about phosphorus volatility.

The 48-hour technique was periodically interrupted for small, half-gram samples on which PEI120 values at several exposure periods could also be determined thus giving a PEI ‘time and decomposition scan’ at the temperature chosen. Both techniques worked well and will be again part of the effort to develop correlation with field tests. Very preliminary information is promising but requires study of precision of the new techniques.


First work at 120°C used the 16-hour protocol (PEI120-16), and gave sufficient sample for analysis., also led to a more extended 48-hour, 120°C technique.

Future WorkSuch preliminary work at 120°C may provide a higher level of PEI precision than at higher temperatures. However, this precision remains to be shown with replicate studies.

Correlation of the PEI protocols with engine data both on the dynamometer as well as in the field remains at a high level of interest for OEMs and additive suppliers.

The same may be said of coming work at temperatures of 150° to 165°C and the study of the decomposition products of such PEI analyses through NMR techniques.

Promising cooperative work with both OEMs and others is underway with correlative data that will, with hope, be soon available and directive regarding a bench test for phosphorus volatility.


From very recent studies the two temperatures of 120° and 150°-165°C have emerged as being of interest and specific PEI protocols developed for application to engine studies.

phosphorus emission index (pei) studies of zddp in engine oils escit meeting, 2006 august 8 at...

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