Using the oxygenates. Oxygenates were used originally simply as an additive to
improve octane number. However, because of their oxygen content, they are now
added also to reduce carbon monoxide and hydrocarbon in the emission gases.
There are a number of oxygenates now used in gasoline manufacture; some of the
more common are given in Table 12.
The EPA has established limits for the use of each oxygenates in gasoline
blends. For example, MTBE may be blended up to 15 % vol subject to an overall
limit of 2.7 % wt oxygen content. The role of MTBE and other oxygenates in the
USA was discontinued in 2002 after it was discovered that underground storage
Table 10 A gasoline recipe prior to 1990
Component
% vol
Aromatics % vol Olefins % vol ON res clear ON ratio
Butane
3.75
0
0
92
3
LSR
12.5
10
2
69
8
Reformate
24.39 89
0
91
18
Lt crack naphthas
12.5
35
89
18
Hy crack naphthas
21.19 53
90
19
Alkylate
25.67
0
0
95
24
Total
100.00 31.0
12.0
90
SG at 60
F 0.7749
RVP 7.0 psig
Table 11 A gasoline recipe post 1996
Component
% vol
Aromatics % vol
Olefins % vol
ON res clear
ON ratio
Butane
1
0
0
92
0.9
LSR
15
0
0
69
10.0
Reformate
30
60
0
80
24.0
Cat naphthas
32
25
35
82
26.0
Alkylate
20
0
0
95
27.0
MTBE
2
0
0
110
2.1
Total
100
26
11.2
90.0
Table 12 Oxygenates commonly used in gasoline (except for ethanol, subject to phase out in the
USA)
Name
Formula
RON
RVP
psig
Oxygen
% wt
Water
solubility %
a
Methyl tertiary butyl
ether (MTBE)
(CH 3 ) 3 COCH 3
110–112
8
18
4.3
Ethyl tertiary butyl ether
(ETBE)
(CH 3 ) 3 COC 2 H 5 110–112
4
16
1.2
Tertiary-amyl methyl
ether (TAME)
(CH 3 ) 2 (C 2 H 5 )
COCH 3
103–105
4
16
1.2
Ethanol
C 2 H 5 OH
112–115 18
35
100
a
wt% soluble in water
Petroleum Products and a Refinery Configuration
75
improve octane number. However, because of their oxygen content, they are now
added also to reduce carbon monoxide and hydrocarbon in the emission gases.
There are a number of oxygenates now used in gasoline manufacture; some of the
more common are given in Table 12.
The EPA has established limits for the use of each oxygenates in gasoline
blends. For example, MTBE may be blended up to 15 % vol subject to an overall
limit of 2.7 % wt oxygen content. The role of MTBE and other oxygenates in the
USA was discontinued in 2002 after it was discovered that underground storage
Table 10 A gasoline recipe prior to 1990
Component
% vol
Aromatics % vol Olefins % vol ON res clear ON ratio
Butane
3.75
0
0
92
3
LSR
12.5
10
2
69
8
Reformate
24.39 89
0
91
18
Lt crack naphthas
12.5
35
89
18
Hy crack naphthas
21.19 53
90
19
Alkylate
25.67
0
0
95
24
Total
100.00 31.0
12.0
90
SG at 60
F 0.7749
RVP 7.0 psig
Table 11 A gasoline recipe post 1996
Component
% vol
Aromatics % vol
Olefins % vol
ON res clear
ON ratio
Butane
1
0
0
92
0.9
LSR
15
0
0
69
10.0
Reformate
30
60
0
80
24.0
Cat naphthas
32
25
35
82
26.0
Alkylate
20
0
0
95
27.0
MTBE
2
0
0
110
2.1
Total
100
26
11.2
90.0
Table 12 Oxygenates commonly used in gasoline (except for ethanol, subject to phase out in the
USA)
Name
Formula
RON
RVP
psig
Oxygen
% wt
Water
solubility %
a
Methyl tertiary butyl
ether (MTBE)
(CH 3 ) 3 COCH 3
110–112
8
18
4.3
Ethyl tertiary butyl ether
(ETBE)
(CH 3 ) 3 COC 2 H 5 110–112
4
16
1.2
Tertiary-amyl methyl
ether (TAME)
(CH 3 ) 2 (C 2 H 5 )
COCH 3
103–105
4
16
1.2
Ethanol
C 2 H 5 OH
112–115 18
35
100
a
wt% soluble in water
Petroleum Products and a Refinery Configuration
75