t-butyl alcohol in internal combustion engines

What would be the consequences of using 100% TBA in internal combustion engines?

It's got a RON of 105 and a MON of 95.

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Mike

[Only registered users see links. ] (Mike Darrett) wrote:


The first thing that comes to mind is that the fuel would turn solid
at 26C (m.p.).

Roger

It seems to me that you would have to re-jet the carburator, and there
would be some content of TBA emissions. The spark timing would have to
be adjusted, and optimal compression ratios would have to be
determined. Also, In my short experience in working with it, I noticed
that it tends to solidify at a impractically high temperature, at
least for automobiles.
The link you posted seems to relate to ether reaction products of
TBA, not TBA itself.-Jitney

[Only registered users see links. ] (Mike Darrett) wrote:


You wouldn't get very far on cold days, it's got a narrow liquid range,
melting point 25C, boiling point 84C. I haven't checked, but I think
the above octane values are blending octanes, not actual octanes.

TBA was permitted in US fuel up to ~2.7 when used as a 1:1 blend with
methanol, and the blend was used as an octane-enhancing additive. As
with most such additives, yes they will work in a suitable engine,
but the practical problems ( trying to achieve and maintain exhaust
emission limits and the need to keep the fuel liquid without generating
volatile emissions ) make pure TBA about as unattractive as pure MTBE.

Bruce Hamilton

Bruce Hamilton <[Only registered users see links. ].nz> wrote in message news:<[Only registered users see links. ]>. ..


Yes, completely forgot that t-buOH is solid at room temperature. I
vaguely recall our reaction engineering lab class involved the
kinetics of the dehydration of t-butyl alcohol... and yes it was a
mess to try and heat up the jug to pour into the rxn vessel.

Ok, how about isopropyl alcohol? I'm basically wondering if a
suitable alcohol can be found that will burn properly in unmodified
gasoline engines (no modifications to the compression ratio, for
instance). I'm guessing the ethers would suffer from possible
peroxide formation?

TIA

Mike

Mike Darrett ([Only registered users see links. ]) wrote:
: Bruce Hamilton <[Only registered users see links. ].nz> wrote in message news:<[Only registered users see links. ]>. ..
: > [Only registered users see links. ] (Mike Darrett) wrote:
: >
: > >What would be the consequences of using 100% TBA in internal combustion engines?
: > >It's got a RON of 105 and a MON of 95.
: > >[Only registered users see links. ]
: >
: > You wouldn't get very far on cold days, it's got a narrow liquid range,
: > melting point 25C, boiling point 84C. I haven't checked, but I think
: > the above octane values are blending octanes, not actual octanes.
: >
: > TBA was permitted in US fuel up to ~2.7 when used as a 1:1 blend with
: > methanol, and the blend was used as an octane-enhancing additive. As
: > with most such additives, yes they will work in a suitable engine,
: > but the practical problems ( trying to achieve and maintain exhaust
: > emission limits and the need to keep the fuel liquid without generating
: > volatile emissions ) make pure TBA about as unattractive as pure MTBE.
: >
: > Bruce Hamilton


: Yes, completely forgot that t-buOH is solid at room temperature. I
: vaguely recall our reaction engineering lab class involved the
: kinetics of the dehydration of t-butyl alcohol... and yes it was a
: mess to try and heat up the jug to pour into the rxn vessel.

: Ok, how about isopropyl alcohol? I'm basically wondering if a
: suitable alcohol can be found that will burn properly in unmodified
: gasoline engines (no modifications to the compression ratio, for
: instance). I'm guessing the ethers would suffer from possible
: peroxide formation?

Why not use ethanol? It is mandated as an oxygenator in some states
(especially in the northern plains). They usually make it 10%. It is an
oxygenator as well as an antiknocking agent. As an added bonus, it dries
out your fuel lines in the winter. In some service stations in the
Minneapolis area, they sell 85% ethanol gasoline. Most new cars can run
on 85% EtOH.

--
--
William "Dave" Thweatt
Robert E. Welch Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
[Only registered users see links. ]
[Only registered users see links. ]

In article <bpu1ur$g49$[Only registered users see links. ].edu> [Only registered users see links. ] (William David Thweatt) writes:
<Mike Darrett ([Only registered users see links. ]) wrote:
<: Bruce Hamilton <[Only registered users see links. ].nz> wrote in message news:<[Only registered users see links. ]>. ..
<: > [Only registered users see links. ] (Mike Darrett) wrote:
<: >
<: > >What would be the consequences of using 100% TBA in internal combustion engines?
<: > >It's got a RON of 105 and a MON of 95.
<: > >[Only registered users see links. ]
<: >
<: > You wouldn't get very far on cold days, it's got a narrow liquid range,
<: > melting point 25C, boiling point 84C. I haven't checked, but I think
<: > the above octane values are blending octanes, not actual octanes.
<: >
<: > TBA was permitted in US fuel up to ~2.7 when used as a 1:1 blend with
<: > methanol, and the blend was used as an octane-enhancing additive. As
<: > with most such additives, yes they will work in a suitable engine,
<: > but the practical problems ( trying to achieve and maintain exhaust
<: > emission limits and the need to keep the fuel liquid without generating
<: > volatile emissions ) make pure TBA about as unattractive as pure MTBE.
<: >
<: > Bruce Hamilton
<
<
<: Yes, completely forgot that t-buOH is solid at room temperature. I
<: vaguely recall our reaction engineering lab class involved the
<: kinetics of the dehydration of t-butyl alcohol... and yes it was a
<: mess to try and heat up the jug to pour into the rxn vessel.
<
<: Ok, how about isopropyl alcohol? I'm basically wondering if a
<: suitable alcohol can be found that will burn properly in unmodified
<: gasoline engines (no modifications to the compression ratio, for
<: instance). I'm guessing the ethers would suffer from possible
<: peroxide formation?
<
<Why not use ethanol? It is mandated as an oxygenator in some states
<(especially in the northern plains). They usually make it 10%. It is an
<oxygenator as well as an antiknocking agent. As an added bonus, it dries
<out your fuel lines in the winter. In some service stations in the
<Minneapolis area, they sell 85% ethanol gasoline. Most new cars can run
<on 85% EtOH.

And it has the additional advantage of those billyuns and billyuns
of tiny buggies floating about just waiting to make it for you
for (essentially) free.


-- cary

"Mike Darrett" <[Only registered users see links. ]> wrote in message
news:d945119c.0311232218.3dd6c280@posting.google.c om...
news:<[Only registered users see links. ]>. ..
engines?

For the first time you've used the word "unmodified" so the answer is NO!

Alcohols are "low energy" (having oxygen in the molecule) and need serious
modifications to air/fuel ratios. I don't think you'll get the right octane
ratings with the lower alcohols. Volatility (lack of) can be a problem too.

Barry Hunt

[Only registered users see links. ] (Mike Darrett) wrote:

Not really. Think of any liquid, and somebody has probably
tried it in an engine - either as a fuel or an additive.

I have some reports about engines running on 100% MTBE, and
DME has also been used. The economic problems shouldn't be
neglected, that's why many of the oxygenates are used as
additives, rather than fuels.

It's quite possible to run oxygenate fuels in unmodified
( if no change in the compression ratio is the metric ),
as we ran 99% methanol ( 1% water to inhibit light metal
corrosion ), 85% ethanol, and some C3 and C4 alcohols
in engines with the major modification being the addition
of a special carburettor and changing the ignition timing
map.

If you don't want to change anything, and you want the
fuels to be compatible with older vehicles, you are stuck
at about 20% oxygenates, as the ignition timing and fuel-
air ratios have to be adjusted to optimise combustion.

The alcohols that have been approved as additives are
usually those that are readily available and can improve
a desirable fuel property - that tend to restrict them
to C1 - C4 size.

There are some vehicles around that are flexible fueled
( FFV ) and some can run on high oxygenate fuels ( up to
99% MeOH, 99% EtOH ).

The fundamental disadvantages of oxygenates remain,
namely oxygen that can't contribute energy and the
cosolvent effect when dissolution in water occurs.


Bruce Hamilton

This got me thinking:

there is a correlation between anti-knock efficiency of
octane-boosting additives and their capability to form stabilized
(=lazy) radicals. Tetraethyl-led, branched alkanes, TBME etc.

If scavenging the radicals in the chain-reaction of the combustion
process is the way to get octane number iboosted, then one can perhaps
use common radical scavengers known from organic synthesis, food
industry, polymer processing. For example, tert-butylated
hydroxytoluene is cheap, non-toxic and highly efficient as a
scavenger. Only a tiny bit would suffice and it would not extract into
groundwater from leaking fuel storage tanks.


Bruce Hamilton <[Only registered users see links. ].nz> wrote in message news:<[Only registered users see links. ]>. ..