Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 726-734
726
Meier. W. M. Z . Krist. 1981, 115, 439. Norton Co. Neth. Appl. 298606, Aug 10, 1965 (Chem. Abstr. 1988, 64, 4856s). Sand, M. L.; Coblenz, W. S.; Sand, L. B. Adv. Chem. Ser. 1971, 101, 127. Wolf, F.; Renning, J. East German Patent 83978, Aug 20, 1971 (Chem. Abstr. 1973, 78, 113434~).
Zhdanov, S.P. Adv. Chem. Ser. 1971,
No. 101, 20.
Received for review November 14, 1980 Revised manuscript received June 1, 1981 Accepted June 1, 1981
Gasohol, TBA, and MTBE Effects on Light-Duty Emissions Bruce B. Bykowski" Department of Emissions Research, Southwest Research Institute, San Antonio, Texas 78284
Robert J. Garbe Emission Control Technology Division, Environmental Protection Agency, Ann Arbor, Michigan 48 705
This article summarizes a report prepared for the Emission Control Technology Division, Environmental Protection Agency, Ann Arbor, Michigan. The report describes the laboratory testing of unleaded gasoline and gasoline mixtures containing ethanol, tert-butyl alcohol (TBA), and methyl teff-butyl ether (MTBE). Four different vehicles were employed in this study. Analytical procedures for the measurement of TBA and ethanol in exhaust and evaporative emissions were developed. Regulated and unregulated emission rates were determined during the entire Federal Test Procedure (FTP) for each vehicle using several gasoline blends. Exhaust emission rates of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NO,), individual hydrocarbons (IHC), and aldehydes are reported in grams per kilometer. Evaporative emissions of total hydrocarbons, TBA, and ethanol are reported in grams.
ethanol, TBA) in the exhaust.
Introduction The effect of ethanol, tert-butyl alcohol (TBA), and methyl tert-butyl ether (MTBE) on exhaust and evaporative emissions was evaluated with several base fuels. Four catalyst-equipped vehicles were set to manufacturers' specifications, and their fuel tanks were modified with thermocouples and drain plugs. They were tested with several fuels in an evaporative emission enclosure and over the dynamometer portion of the Federal Test Procedure (FTP). The vehicles included in the test plan were a 1978 Malibu, a 1978 Mustang, a 1978 Saab, and a 1979 Marquis. During each test, a number of regulated and unregulated emission tests were performed. Aldehydes, individual hydrocarbons, and the regulated emissions were measured on all FTP tests with all fuel blends. Ethanol and TBA were measured in the exhaust and evaporative emissions for their respective fuel blends. In general, the Marquis and Saab did not exhibit an increase in evaporative hydrocarbons, while the Mustang's evaporative emissions increased by a factor of 3. The Malibu evaporative emissions increased between 30 and 40%. The designs of the evaporative emission systems and location of the carburetor relative to engine heat probably caused the variations observed. The CO exhaust emissions were reduced between 15 and 40% when fuel blends were used. There was no significant change in the HC and NO, emissions between the base fuel and the fuel mixtures. The aldehydes and most individual hydrocarbons in the exhaust remained almost the same with the base fuel and fuel blends. No significant quantities of ethanol or TBA were observed in the exhaust. The catalyst efficiency is apparently sufficient to completely oxidize any partially oxidized components (i.e., aldehydes, 0196-4321/81/1220-0726$01,25/0
Preparations and Procedures The vehicles used in this study are described in Table I. The Saab was only used for a part of the study, and the Marquis was substitued to complete the investigation. The various fuels tested used base fuels that met the gasoline fuel specifications listed in the Federal Register (1977). The eight fuels evaluated in the research effort are summarized in Table 11, and their specifications are listed in Table 111. Regulated Emissions All vehicle fueling and emission tests were performed according to the procedures set forth in the Federal Register (1977). The evaporative emission losses (HC), and gaseous emissions of hydrocarbons (HC),carbon monoxide (CO), and oxides of nitrogen (NO,) were collected and analyzed using the procedures and equipment described in the gasoline Federal Test Procedure (FTP). The evaporative emission enclosure (SHED) and related equipment was constructed according to the requirements published in the Federal Register (1977). The running loss test portion of the evaporative emission test, which is optional, was not performed. The fueling of the vehicles employed a drum cooler to maintain a maximum fuel temperatuare of 14 "C. The tests were performed on a Clayton chassis dynamometer. A constant volume sampler (CVS) with a nominal capacity of 0.14 m3/s (300 CFM) was used. Unregulated Emissions Unregulated emissions measured in this study were aldehydes, individual hydrocarbons, ethanol, and tert-butyl 0
1981 American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 727
Table I. Vehicle Description vehicle make Chevrolet year model body type serial number GVMR, kg (lb) engine displacement, L (in.7 engine family emission controls catalysts air pump EGR chassis dynamometer settings inertia, kg (lb) power, kW (hp) fuel tank capacity, L (gal) Table 11. Fuels Evaluated fuel code A
B C
D E
F G H
Saab
Mercury
1978 Malibu 2-dr lW27U82434207 2052 (4523) 5.00 (305) 810Y2V 8BCV
1978 Mustang I1 2-dr 8F02F187610 1857 (4095) 4.95 (302) 302 “D” (1x95)
Ford
1978 99 2 -dr 99781008246 1728 (3810) 1.98 (121) Bl2OCA
1979 Marquis 2-dr 9263H519763 2434 (5365) 5.75 (351) 5.8W “BV” (2TT95x95)
pelleted oxidation Yes Yes
monolith oxidation no Yes
3-way
no no
dual bed Yes no
1590 (3500) 8.0 (10.7) 68.5 (18.1)
1590 (3500) 9.2 (12.3) 62.5 (16.5)
1360 (3000) 8.4 (11.3) 54.9 (14.5)
2040 (4500) 8.9 (12.0) 71.9 (19.0)
description
EM-373-F ASTM unleaded gasoline, EPA No. 3 EM-374-F ASTM unleaded gasoline t 10% ethanol (mixed), EPA No. 4 EM-375-F ASTM summer grade unleaded gasoline t 10% ethanol (blended) EPA No. 6 EM-371-F Indolene, EEE clear EM-372-F Indolene + 1 0 % ethanol, EEE gasohol EM-389-F Indolene, EEE clear EM-385-F EM-389-F + 7% tert-butyl alcohol (TBA), mixed EM-386-F EM-389-F + 7% methyl tert-butyl ether (MTBE), mixed
alcohol. The aldehyde and individual hydrocarbon procedures were employed during the dynamometer run portion of the FTP. The ethanol and TBA procedures were used selectively during both the dynamometer run and the evaporative emission run. Aldehydes were measured using the 2,4-dinitrophenylhydrazine (DNPH) method (Dietzmann et al., 1979). This method consists of withdrawing a continuous sample of dilute exhaust and bubbling the sample through glass impingers containing DNPH in hydrochloric acid. Phenylhydrazone derivatives are formed and are eventually injected into a gas chromatograph using a flame ionization
detector for separation and identification. The term “individual hydrocarbons” is used to define the collection and analysis of the following compounds: methane, ethane, ethylene, acetylene, propane, propylene, benzene, and toluene. The individual hydrocarbon (IHC) procedure (Dietzmann et al., 1979) consists of collecting dilute sample in Tedlar (DuPont Co.) bags, and injecting samples from the bags into a four-column gas chromatograph for separation and identification. The tert-butyl alcohol (TBA) procedure was developed during this research effort in order to measure any TBA emissions due to the addition of TBA to base gasoline. During the dynamometer run portion of the FTP, a continuous sample of dilute exhaust was bubbled through glass impingers containing deionized water. During the evaporative emissions portion of the FTP, two samples were withdrawn from the SHED into Tedlar bags. One bag was collected during the first minute after the SHED door was sealed and the second bag was obtained during the minute prior to the end of the SHED test. High sample flow rates were employed to remove a relatively large sample from the SHED in a short time. The contents of the bag were then drawn through impingers at the same flow rate as the sample collected during the FTP. A sample from each impinger was injected into a gas chromatograph using a flame ionization detector for quantitative analysis. The ethanol procedure was also developed during this investigation in order to measure any ethanol emissions
Table 111. Fuel Specifications item code octane distillation range: IBP, “C 5% 10% 20% 30% 40% 50 % 60% 70% 80% 90% 95% end point RVP, kPa RVP, (psi) hydrocarbon composition olefins, % aromatics, % saturates, %
fuel EM-373-F 92.3
EM-374-F 94.8
EM-375-F 96.4
26 41 49 61 77 93 111 137 143 161 184 197 231 68.9 (10.0)
25 41 48 56 61 96 114 129 137 150 185 193 210 75.2 (10.9)
30 44 51 59 71 85 112 134 149 166 183 196 211 68.9 (10.0)
17.2 29.8 53.0
16.6 28.9 54.5
17.6 34.6 47.8
EM-371-F 96.5 27 43 55 71 87 99 107 114
EM-372-F 98.9
142 163 168 184 62.1 (9.0)
30 47 52 60 67 74 101 111 124 137 160 166 176 66.2 (9.6)
0.4 28.5 71.1
0.6 25.7 73.7
131
EM-389-F 97.0 27 44 56 75 92 101 108 114 126
134 162 170 193 62.7 (9.1) 0.5 30.0 69.5
728
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20,No. 4, 1981
't
co Figure 1. Malibu FTP and evaporative emissions.
from fuels containing ethanol. During both the dynamometer run and the SHED portion of the FTP, a continuous sample of either dilute exhaust or SHED contents was drawn into a Tedlar bag. A sample from the bag was injected into a gas chromatograph using a flame ionization detector for separation and quantification. Development of a procedure for the analysis of methyl tert-butyl ether (MTBE) was attempted without success. Inability to find a suitable trapping medium and the similarity of MTBE with other compounds in gasoline caused problems with collection, separation, and quantification. After a reasonable effort, this procedural development was discontinued. Results Malibu. The regulated emission results for each fuel with the Malibu are shown in Figure 1. The gaseous emissions from the dynamometer run indicated no significant changes in HC and NO, emissions for all eight fuels. The ethanol, TBA, and MTBE fuel mixtures did, however, reduce CO emissions between 20 and 40% compared to their respective base fuels. There was no significant difference in the HC evaporative emissions of the base fuel (Fuel A, EM-373-F) and the two ethanol blends (Fuel B, EM-374-F and Fuel C, EM-375-F). A noticeable difference was observed between the winter grade base fuel (Fuel D, EM-372-F) and the corresponding 10% ethanol blend (Fuel E, EM-372-F). The increase in the evaporative emissions was about 40% due to the ethanol in the winter grade fuel. A second batch of base fuel was used with the additives TBA and MTBE. The 7% TBA in the base fuel had essentially no effect on the evaporative emissions, but for the MTBE blend (Fuel H, EM-386-F), a 36% increase in evaporative emissions was observed. Aldehyde, individual hydrocarbon (IHC), and ethanol or TBA concentrations were measured during the dyna-
mometer portion of the FTP. The averages of the data runs are summarized in Table IV. The aldehyde emissions generally increased using the fuels containing ethanol, TBA, and MTBE. It should be noted, however, that the aldehyde data was somewhat scattered due to the observed (low) concentrations approaching the detection limits of the analytical method. There was no significant change in the individual hydrocarbons due to the ethanol, TBA, or MTBE, except that methane emission rates were about 20% lower with TBA and MTBE than with the corresponding base fuel. No ethanol or TBA was observed in the exhaust (MTBE measurements were not made). Ethanol evaporative emission rates typically ranged from 2 to 3 g/test. TBA evaporative emissions ranged from 3 to 7 g/test accounting for an estimated 15-25% of the evaporative hydrocarbons. It should be noted that the total hydrocarbon values obtained from the SHED are "as measured" and are not corrected for ethanol, TBA, or MTBE FID responses. Mustang. The average emission rate for the FTP exchaust and SHED emission is presented as the bar graph in Figure 2. As illustrated, essentially no change in the HC exchaust emissions was observed with the fuel blends. This was not the case where the NO, levels decreased slightly (about 15%) with the base fuel with ethanol. With TBA and MTBE, the NO, emissions increased by 10% relative to the base fuel. The CO emission rates decreased with all fuel blends, ranging from a 15-30% reduction. The average hydrocarbon evaporative emissions for each test fuel is presented in Figure 2. The HC evaporative emissions increased by a factor of 3 with the ethanol blends, doubled with the TBA blend, while increasing only slightly with the MTBE blend. The Mustang was the most sensitive to the fuel blend composition. During the dynamometer portion of the FTP, aldehyde and individual hydrocarbons were measured. Measure-
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 729 Table IV. Malibu Average Unregulated Emissions Results Average Aldehyde, mg/km
fuel
form.
acet.
EM-373-F EM-374-F EM-375-F EM-371-F EM-372-F EM-389-F EM-385-F EM-386-F
1.51 1.12 1.71 0.93 1.72 0.56 1.59 0.84
0.34 0.50 0.59 0.06 0.54
methyl ethyl acetone” isobutyl. ketone 0.09 0.28 0.03 0.06 0.08 0 0.19 0.13
0
0.37 0.06
0 0 0 0 0 0 0 0
croton.
0.06 0.03 0.06 0.12 0.10 0 0 0
hexan.
benzene
total
0.11 0 0.06 0.16 0.17 0 0 0
0.08 0 0 0 0.31 0.43 0.41 0.81
2.19 1.92 2.45 1.33 2.92 1.01 2.61 1.90
Average Individual Hydrocarbon, mg/km fuel
methane
ethylene
ethane
acetylene
propane
propylene
benzene
toluene
EM-373-F EM-374-F EM-37 5-F EM-371-F EM-372-F EM-389-F EM-38 5-F EM-386-F
46.96 45.64 44.00 43.31 38.38 57.98 45.24 45.18
19.99 21.66 20.91 10.44 10.69 12.57 10.89 11.13
10.00 10.36 10.19 9.73 10.05 8.90 9.67 9.72
2.40 2.73 3.64 1.16 2.77 1.99 1.49 1.74
4.16 1.41 1.68 1.80 2.05 1.96 2.11 2.15
3.34 4.13 3.79 4.08 3.27 5.02 4.17 4.35
6.95 6.06 7.55 2.94 2.24 5.29 4.04 3.45
7.59 8.32 8.49 8.10 7.97 26.76 20.71 19.98
fuel EM-372-F EM-372-F EM-372-F EM-374-F EM-374-F EM-375-F EM-375-F EM-385-F EM-385-F EM-385-F
date 11-29-78 11-30-78 12-1-78 11-12-7 8 11-13-78 11-15-78 11-20-78 5-14-79 5-15-79 5-25-79
component ethanol ethanol ethanol ethanol ethanol ethanol ethanol TBA TBA TBA
DBL 1.45 1.60 0.96 1.77 1.67 1.88 1.51 0.65 0.19 0.40
evaporative, g HSL total 1.61 3.06 1.61 3.21 1.44 0.48 1.14 2.91 0.48 2.15 0.32 2.20 0.43 1.94 0.06 0.71 0.06 0.25 0.45 0.05
FTP, g/km 0 0 0 0 0 0 0 0 0 0
” Includes acrolein and propanol. ments for TBA and ethanol were made also when fuels containing these components were used. The data are averaged and summarized in Table V. The low concentration of aldehydes observed caused some scatter as seen before. Generally the total aldehydes increased using fuels containing ethanol and TBA. Fuel H, MTBE mixture, may have reduced total aldehydes by forming less formaldehyde as the data indicated. The individual hydrocarbons remained fairly consistent within each group of base fuel and mixtures. Again, there was no significant change in the individual hydrocarbons due to the ethanol, TBA and MTBE. The only exception was methane, which was reduced by about 20% with TBA and MTBE. Ethanol and tert-butyl alcohol were not detected in the exhaust. The oxidation catalyst on this vehicle probably oxidized any unburnt alcohols. Table V also contains the evaporative alcohol emissions. The results are repeatable for each fuel tested and indicate that most of the alcohol evaporative losses occur during the hot soak portion of the SHED test. During the hot soak portion, which occurs immediately after the dynamometer run, the vehicle’s engine is hot. The carburetor fuel bowl on this vehicle is very close to the intake manifold. This position could cause a fuel with a lower boiling point, such as the alcohol mixture, to boil out more readily than the base fuel. The ethanol evaporative emission rates were about 6 g/test for the summer grade ethanol blends accounting for about 25% of the total HC evaporative emission. The ethanol evaporative emission rate increased to 11 g/test with the winter grade fuel accounting 65% of the hydrocarbons (on an as-measured basis with no FID response
factors applied). Those tests with the TBA indicate that the TBA accounts for essentially all of the SHED HC evaporative emissions. Saab. Figure 3 illustrates comparison of the average emission rate for HC, CO, and NO, from FTP and HC from SHED tests. There were no significant changes in the HC and NO, FTP emission rates due to the ethanol, whereas there was a definite decrease (approximately 10-20%) in CO emission with both ethanol blends. HC evaporative emissions were essentially unaffected by the ethanol fuel blends. The SHED HC evaporative results were conflicting in that one ethanol blend increased HC emissions, one was lower, and one was equal to the comparable base fuel. Individual hydrocarbon (IHC), aldehyde, and ethanol emissions were measured during each dynamometer run. The data for each fuel have been averaged and are listed in Table VI. As discussed previously, and especially in this case, the aldehyde emissions were very low and near the detection limits of this analytical method. They did not indicate any definite trends. IHC results showed that methane was 20% lower with Fuel E (EM-371-F)then with base fuel F (EM-373-F). No changes in methane emission rates were observed with Fuels A, B, and C (EM-373-F, EM-374-F, and EM-375-F). The remaining individual hydrocarbons were only slightly affected or showed no definite trends. No ethanol was observed in the exhaust. The evaporative ethanol emissions are also listed in Table VI. The repeatability for each ethanol fuel mixture was good. Fuel C (EM-375-F) and fuel E (EM-373-F) exhibited similar results on both portions of the evaporative test. Fuel B (EM-374-F) emitted approximately a
730
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20,No. 4, 1981
1980
7
Emissions Standards
L
Fuel EM-373-F EM-374-F EM-375-F 3 = EM-371-F E = EM-372-F F = EM-389-F G = EH-385-F il = EM-3d6-F A =
5
B = C =
4 E
I 1 I
I
Y \ F
I
I
U
I
a
x3
I I
n
I
2 E
I
g 2 6
I
I
t
1
L
l " l A
B
C
D
E
F
G
-
H
a
c
A
B
C
D
E
F
ti
I I
A
~
I
HC
I
CE
F
G
H
SHED
NO,
Figure 2. Mustang total FTP emissions. 1335 E : o i s s i o n s Standards
-
t:.
Fuel
A = EM-373-F 3 = EM-374-F C = EM-375-F D = EM-371-F E = EM-372-F
n
A
b
c
HC
D
L
~
L
C
co
Figure 3. SAAB FTP and evaporative emissions.
J
E
A
B
L
3
NO,
L
' '
A
E
C
D
SHED
E
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 731 Table V. Mustang Average Unregulated Emissions Results Average Aldehyde, mglkm
fuel
form.
acet. -
acetone a
isobuty.
methyl ethyl ketone
EM-373-F EM-374-F EM-375-F EM-371-F EM-372-F EM-389-F EM-385-F EM-386-F
1.36 1.34 2.15 1.43 1.47 1.39 2.27 0.44
0.17 1.06 2.02 0 0.91 0.25 0.34 0.03
0.04 0.41 0.34 0.06 0.10 0.08 0.16 0
0 0 0.06 0 0 0.10 0.19 0
0.04 0.10 0.06 0.16 0.06 0.06 0 0
croton. 0 0 0
0 0 0 0.03 0.12
hexan.
benzene
0.12 0.10 0.13 0.19 0.17 0 0 0
0.28 1.28 1.28 0.31 0.47 1.59 1.40 0.19
total 1.96 4.39 6.06 2.18 3.18 2.62 4.38 1.09
Average Individual Hvdrocarbon. melkm fuel
methane
ethylene
ethane
acetylene
propane
propylene
benzene
toluene
EM-373-F EM-374-F EM-375-F EM-371- F EM-372-F EM-389-F EM-385-F EM-386-F
49.92 56.83 50.18 43.54 46.32 58.17 45.37 46.20
32.87 36.29 35.51 16.75 15.74 23.19 20.10 14.98
22.47 23.93 21.50 24.07 24.65 20.64 19.61 17.00
1.70 3.17 1.55 3.06 1.70 2.57 1.59 2.09
4.89 4.54 13.55 6.23 6.77 4.66 5.16 3.95
14.48 11.81 11.72 11.37 11.07 28.30 12.71 9.82
16.22 16.75 16.41 10.29 6.81 21.46 11.99 10.13
13.80 21.94 18.70 25.91 22.31 72.03 59.13 53.25
evaporative, g fuel
date
component
EM-372-F EM-372-F EM-374-F EM-374-F EM-375-F EM-375-F EM-385-F EM-385-F
11-29-78 11-30-78 11-12-78 11-13-78 11-14-78 11-15-78 5-14-79 5-15-79
etha no1 ethanol ethanol ethanol ethanol ethanol TBA TBA
DBL 0.01 0.12 0.06 0.05 0.06 0.09 0 0
HSL
total
FTP, g/km
5.42 6.39 11.50 9.47 9.38 8.04 1.10 1.32
5.43 6.51 11.56 9.52 9.44 8.13 1.10 1.32
0 0 0 0 0 0 0 0
Includes acrolein and propanol.
-.
7
198d L.ussion Standards
-
"24
-22
4
/u
5
..-
Fuel
-.20
F = EM-389-F G = EM-385-F H = EM-386-F
-18
I I I
4--
-16
I
OI
I
-14
;
I t I
-.12
5 2
I I
-.lo
I E
c 3--
--
J1 Y Y
&
2--
VI
wE b
+!
I
P
I vi m
c 1-.
U
43:
I
4
I I I
t
2
I I
0
HC Figure 4. Marquis FTP and evaporative emissions.
co
2 w
I I
a [r
-&
I I
--
wE
5
u
SHED
732
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981
Table VI. Saab Average Unregulated Emissions Results Average Aldehyde, mg/km
fuel
form
acet.
EM-373-F EM-374-F EM-374-F EM-371-F EM-372-F
0.23 0.17 0.35 0.19 0.21
0.19 0.18 0.04 0.19 0.23
acetonea isobuty. 0.03 0.14 0.03 0.09 0.04
methyl ethyl ketone
0 0 0 0 0
croton. hexan.
__ __
0.08 0.06 0.06 0.16 0.12
-_ _-
__
benzene
total
0.17 0.08 0.09 0.22 0.19
0.28 0.08 0 0.41 0.10
0.98 0.60 0.82 1.25 0.89
Average Individual Hydrocarbon, mg/km fuel
methane
ethylene
ethane
acetylene
propane
propylene
benzene
toluene
EM-373-F EM-374-F EM-37 5-F EM-371-F EM-372-F
33.04 30.34 30.64 20.41 16.41
15.37 14.20 16.50 9.46 7.91
5.59 4.60 4.94 3.18 2.73
2.61 2.68 3.20 1.90 1.82
1.15 0.78 1.40 0.31 0.60
6.42 5.81 6.03 6.60 5.45
15.19 11.89 14.29 7.55 6.36
9.88 9.34 12.46 12.21 10.11
evaporative, g fuel
date
component
DBL
HSL
total
FTP., -. elkm
EM-372-F EM-37 2 -F EM-374-F EM-375-F EM-375-F
11-30-78 12-1-78 11-21-78 11-15-78 11-16-78
ethanol etha no1 ethanol ethanol etha no1
0.40 0.53 0.22 0.32 0.27
0.55 0.68 0.14 0.68 0.86
0.95 1.21 0.36 1.00 1.13
0 0 0 0 0
a Includes acrolein and propanol.
..-
A I?
___
-.
= Malliiu =
!.!ustanq
C = Saat
3 = Marquis
11: i I:
T ii;i
... ... ...' *.' ... ..
'..a a..', a'.'
... ... .. :v.* ... ... ... ... ... ... ... ... ... ... .'... ...'..
--I..*...
I
I.*. ' ..
.*A.
.e...a.
I,
i,
Figure 5. Carbon monoxide emission rate summary for all types of test fuels.
third of the ethanol emissions as Fuels C (EM-375-F)and E (EM-372-F). Fuels C and E are similar to one another as far as evaporative emissions are concerned, but dissimilar in the area of exhaust emissions. The fuel specifications support this observation in that both Fuels C and
E have identical initial boiling points but a large variance in hydrocarbon composition. Marquis. Average CO, HC, and NO, FTP emissions and SHED evaporative emissions are illustrated in Figure 4. CO emissions were reduced 30-40% with both the TBA
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20,
No. 4, 1981 733
Table VII. Marquis Average Unregulated Emissions Results Aldehyde, mg/km
fuel EM-389-F EM-385-F EM-386-F
form. 0.73 1.03 1.00
acet. 0.02 0 0
acetonea 0.09 0 0
methyl ethyl ketone 0.07 0 0
isobutv. 0.10 0.03 0
croton. 0.04 0 0.09
hexan. 0 0 0
benzene 0.78 0 0.03
total 1.37 1.06 1.12
Individual Hydrocarbon, mg/km fuel
methane
ethylene
ethane
acetylene
propane
propylene
benzene
toluene
EM-389-F EM-385-F EM-386-F
48.72 41.45 41.79
3.09 2.36 2.83
3.33 3.64 3.48
3.19 1.65 2.30
1.41 0.94 0.72
1.91 1.18 1.43
3.94 2.21 2.49
14.42 9.54 11.37
evaporative, g fuel EM-385-F EM-385-F a
date 5-14-79 5-15-79
compound TBA TBA
DBL 0 0
HSL 0.047 0.055
total 0.047 0.055
FTP, g/km 0 0
Includes acrolein and propanol.
Figure 6. Hydrocarbon evaporative emission summary for all types of test fuels.
and MTBE fuel blends. There was no effect on the NO, emissions with the fuel blends, while only a slight decrease in HC emissions was observed. The TBA and MTBE had no effect on the HC evaporative emissions. Individual hydrocarbon, aldehyde, and TBA emissions were also measured during the dynamometer run. Table VI1 lists the average for the data. Again, the aldehyde emissions are low and the data inconclusive. The individual hydrocarbon results indicate trends previously seen on the other vehicles. Methane emissions were reduced approximately 20% with Fuels G and H, while the other
hydrocarbons remained fairly constant. The exhaust did not contain any measurable amounts of TBA. The evaporative TBA emissions are also listed in Table VII. Results indicate that all the TBA measured came from the hot soak portion of the test. This vehicle exhibited the lowest evaporative emissions, both TBA and HC, of all the vehicles evaluated in this study. Discussion The results of this research effort indicated that fuel mixtures containing ethanol, tert-butyl alcohol (TBA), and
134
Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 734-740
methyl tert-butyl ether affected regulated exhaust and evaporative emissions in the same general manner for the vehicles tested. Little or no effect on HC or NO, emission rates was observed with any of the aforementioned fuel supplements. Carbon monoxide emission rates were reduced significantly with all fuel blends on all four test vehicles. This reduction is summarized as a bar graph in Figure 5. An earlier study (Brinkman et al., 1975) on noncatalyst vehicles indicated similar trends. A comparison of the evaporative hydrocarbons for the various test fuels is summarized in Figure 6. Of the four test cars in the program, the fuel blends had the least effect on the Saab and Marquis. The Mustang and the Malibu showed increased evaporative emissions with two of the three fuel blends. No increase was observed in the unregulated emissions measured in the exhaust. Significant amounts of fuel additives (i-e., ethanol, TBA, or MTBE) in the evaporative emissions were observed on some tests. In general, the test-to-test variability of evaporative emissions is considerably greater than for exhaust emis-
sions. This scatter is due in part to the design and location of the specific HC evaporative emission control system. Use of fuels studied in this project should not interfere with meeting Federal Emissions Standards for gaseous emissions generated on the dynamometer portion of the FTP by the vehicles tested. Depending on the evaporative system of the vehicle, the ability of the test vehicles to meet the HC Evaporative Emission Standard was affected in some cases.
Literature Cited Brinkman, N. D.; GabpauJos, N. E.;Jackson, M. W. “Exhaust Emissions, Fuel Economy and Driveability of Vehicles Fueled with AlcohoKjasoline Blends”, Paper 750120, presented at SAE Engineering Congress, Detroit, Mlch., Feb 1975. Dietzmann. H. E., et al. “Analytical Procedures for Characterizlng Unregulated Pollutant Emissions from Motor Vehicles”; Envlronmental Science Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, N.C., Feb 1979. Fed. Regist. June 28, 1977, 42, No. 124, Part 111.
Received for review April 13, 1981 Accepted August 13,1981
Phosphoric Acid Systems. 2. Catalytic Conversion of Fermentation Ethanol to Ethylene Donald E. Pearson,’ Robert D. Tanner,’2 I. Daniel Plcclotto,2Jason S. Sawyer,‘ and James H. Cleveland, Jr.’ Departments of Chemistry and Chemical Engineering, Vanderbitt University, Nashville, Tennessee 37235
A bottleneck in the development of an economical chemicaVfermentation process for converting starch and cellulose into ethanol for a fuel is the separation of the alcohol from water. Recently, it has been demonstrated that the energy required for recovery by distillation can be reduced tenfold if the ethanol concentration in the recovered product is allowed to drop from 100% to 80% (by weight). One method proposed to complete the separation of water, expending rile energy, is to chemically react the microbhlly derived alcohol. It is suggested that a liquid phase catalyzed process be developed to convert the alcohol to an easily separated gas, such as ethylene, at temperatures ranging between 160 and 300 O C . The effect of process conditions such as temperature and agitation of the mixture on the rate, the yield, the water recovery, and the number of regenerations of the proposed acid catalyst is reported.
Introduction An alternative to conventional separation processes, such as distillation (Bojnowskiand Hanks, 1979),crystallization (Heist, 1979),or extraction (Hanson, 1979) for the removal of fermentation-derivedethanol from water is to chemically react the alcohol into desirable hydrocarbon products. When the original fermentation solution is pre-concentrated to around 80% by weight alcohol, a liquid polyphosphoric acid catalyzed reaction can yield ethylene (a gas) at temperatures between 150 and 300 “ C . Use of only one fractionation stage, following the suggestion of Ladisch and Dyck (1979), minimizes both energy and capital expenditures. The ethylene is easily separable from the polyphosphoric acid-alcohol-water reaction mixture: the ethylene gas evolves directly and only requires gaseous water removal for purification. At higher temperatures, Department of Chemistry Department of Chemical Engineering 0196-4321/81/1220-0734$01.25/0
the gaseous water product is also carried with the ethylene, and almost completely removed from the ethylene by passing the mixture through room temperature water. The process development, described in this paper, is both qualitative: e.g., more vigorous mixing enhances the rate of reaction, and quantitative: the effect of temperature on the reaction rate, product mix, and yield can all be described in terms of classical kinetic models. As a gasoline substitute, “ethanol fuel production now amounts to 60 million gallons per year (4000barrels per day), and is expected to reach 300 million gallons per year (20000 barrels per day) by 1982” (DOE, 1979). “Unsubsidized, fermentation ethanol currently sells for $1.20 to $1.50 per gallon. By employing advanced technology in large-scale plants, it should be possible to produce ethanol and sell it profitably at $1.00 per gallon” (DOE, 1979). In Brazil, the alcohol is being considered as raw material for chemicals now derived from imported petroleum. These chemicals include acetaldehyde, acetic acid, buta0 1981 American Chemical Society
