Fuel Ethers increase Refining Flexibility and Gasoline Production
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The high all round octane of fuel ethers is higher compared to aromatics and ethanol (see below table). This provides refiners with significant flexibility as they can readily substitute for the other high octane components a refiner has to make such as reformate, alkylate and isomerate. If fuel ethers are used in combination with these components then it is possible to produce larger quantities of gasoline.
It is no longer possible to blend light olefins in their pure form due to their high volatility. Ethers provide the possibility of blending light olefins in gasoline. This is one of the reasons for their widespread use in the expanding markets in Asia. By way of an example, the use of 10 % MTBE increases gasoline production by 12.5 %. Likewise access to a high octane blending component is particularly valuable during refinery outages and distribution system disturbances when additional supplies are needed most.
|
|
Motor Octane
Number (MON) |
Research Octane
Number (RON) |
Blending
Vapour
Pressure (kPa) |
Boiling
Point
(°C) |
Sensitivity
(RON-MON) |
|
ETBE
MTBE
TAME
TAEE |
103
101
98
98 |
119
118
112
112 |
28
55
17
7 |
73
55
86
101 |
16
17
14
14 |
|
Benzene
Toluene
P-Xylene
Ethanol |
88
93
98
96 |
106
114
120
130 |
11
4
1
200/138* |
80
111
138
78 |
18
21
22
34 |
| EU Petrol |
85 |
95 |
60 |
26-230 |
|
* 5 and 10% respectively in petrol: derived from Abengoa data
Many refineries have FCC and steam crackers which produce mixed C4 and C5 olefinic streams. These highly reactive and volatile materials were historically added to gasoline. The progressive tightening of the EU fuel quality standards has effectively made this impossible. However, they can be included if they are converted into ethers or bio-ethers.
Thus another attraction of fuel ethers is that they take two substances which could not individually be used in gasoline and turn them into a product with almost perfect blending properties for gasoline.