Alcohol Octane

8/12/2019 Alcohol Octane

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Overview

~ Background

~ Objectives

~ Methodology

~ Results

~ Conclusions


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Background - Pressures on refiners

~ Vehicle manufacturers are

demanding higher octane

unleaded gasoline

~ Use of oxygenates is an

alternative to reduce carbon

monoxide emissions

~ January 2006 total Pb phase

out in SA oxygenates to

cater for octane deficit


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Background - Sasols Experience with Oxygenates

~ Experience with alcohol 8-12

vol % in gasoline 1981-2001

~ Experience with alcohol below

2 vol % in gasoline since

2000

~ Experience with TAME since

introduction of unleaded

gasoline in the South African

market in 1996

~ Have previously shown that

there are synergistic effects

when blending alcohol and

ether in same gasoline blend(ISAF XIV, Thailand, 2002)


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Physical and Chemical Properties

Oxygenate Ethanol MtBE TAME

Chemical Formula C2H60

CH3CH2-0H

C5H120

CH3-O-C(CH3)3

C6H140

C2H5C(CH3)2-O-CH3

Chemical Structure

Molecular Weight 46.07 88.15 102.18

Density, kg/l 0.789 0.740 0.764

Composition, weight

%

Carbon 52.2 68.1 70.5

Hydrogen 13.1 13.7 13.8

Oxygen 34.7 18.2 15.7

Boiling

Temperature, C

77-79 54-56 85-87

Research OctaneNumber

129 116 112

Motor Octane

Number

96 101 99

Reid Vapour

Pressure, kPa

15.86 53.78 10.34

Flash Point, C 12 -28 -11

Water Solubility(g/100mL) Miscible105.1


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Background - Ethers vs. Ethanol

~ Maximum allowable: 15 vol. % vs. 10 vol. % -

3.7 mass% O2

~ Traditionally ethers transported in gasoline via

pipeline ethanol cannot be handled in multi-

product pipelines~ Ethanol blends are not sent through pipeline

systems because they may pick up water and

other impurities in transit.

~ Sasol has successfully transported alcohol

blended in gasoline via pipeline since 1998

~ Gasoline RVP: MTBE & TAME very similar to

gasoline ethanol increases RVP

~ Refiners must reduce lighter components in

summertime to reduce VOCs

vs


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Objectives

~ The objective of this blending study was to verify/quantify the

possible octane benefits of using fuel alcohol (EtOH) and the

ethers (MTBE and TAME) as co-oxygenates in unleaded

gasoline blending.

~ This study comprises the blending octane properties of 95/5

Sasol Fuel Alcohol (SFA) (95% ethanol and 5% propanol)

produced by the Sasol Synfuels facility, and TAME and MTBE

over a concentration range of 3% and 1 10% respectively.


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Methodology - Octane Synergies

~ Synthetic and Petroleum derived unleaded gasoline containing 3volume percentage Sasol Fuel Alcohol (SFA) were used as base fuels

~ Ether (MTBE and TAME) was added, at increasing addition rates by

volume, to determine the effect of the oxygenates on the octanenumbers (RON and MON)

~ As a reference, gasoline blends with no oxygenates were used and the

ethers were added in same ratios as mentioned above

~ Octane ratings of the blends were determined as per ASTM standardtest methods

~ The blending octane of the oxygenates was determined using linearequations


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Results - Blending Research Octane Number

105

110

115

120

125

130

TAME in FT Base MTBE in FT Base TAME in Pet Base MTBE in Pet Base

0 vol% SFA

3 vol% SFA

~The increase of the BRON when SFA is added petroleum based

gasoline is significantly higher if compared with FT based gasoline


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Results - Blending Motor Octane Number

94

96

98

100

102

104

106

108

110


0 vol% SFA

3 vol% SFA

~The addition of SFA reduce the BMON of both TAME and MTBE

for FT base gasoline


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Results - RON Gain in F-T Base Gasoline

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1 % MTBE 3% MTBE 6% MTBE 10% MTBE 1% TAME 3% TAME 6%TAME 10% TAME

Ether Content

w/o SFA With 3-vol% SFA

Base RON = 88.5


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Results - RON Gain in Petroleum Base Gasoline

0

1

2

3

4

5

6

7

1 % MTBE 3% MTBE 6% MTBE 10% MTBE 1% TAME 3% TAME 6%TAME 10% TAME

Ether Content

w/o SFA With 3-vol% SFA

Base RON = 90.8


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Results Ave Delta in Blending Research Octane Number

0

2

4

6

8

10

12

14



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Results Ave Delta in Blending Motor Octane Number

-6

-5

-4

-3

-2

-1

0

1

2

3

4

TAME in FT Base MTBE in FT Base TAME in CO Base MTBE in CO Base


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Discussion

~ The research octane number gain with the addition of ether in

a base gasoline, which contains alcohol, is higher than with a

base gasoline that does not contain any alcohol.

~ The blending octane values of the ethers in the crude oilbased material are higher than the corresponding values in

the Fischer-Tropsch derived material.

~ This may be attributed to differences in olefin content between

the two base fuels without alcohol.


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Conclusions

~ The blending octane ethers compares very well with that of

the values given in literature.

~ Even the addition of low concentrations of alcohol to the

unleaded base fuel has a significant effect on the octanenumber of the resulting gasoline-oxygenate blend.

~ The gain in octane with the addition of ether is higher with a

base fuel containing alcohol.

~ The composition of the base fuel appear to have significanteffect on the blending octane number of the oxygenates, i.e.

high olefin content affects lower blending octane of

oxygenates and vice versa


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Questions?


18/18

Background - Properties of commonly used Oxygenates

Alcohol Octane

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