MTBE.... HYPOCRISY 
Author Message
 MTBE.... HYPOCRISY


:> I think you are right.  I seem to recall that MTBE burns at something
:> like 2000 degrees F.  So no way is it burning in car engines.

: Once again: MTBE is not a catalyst, it is a source of oxygen. For it to
: release that oxygen, it MUST break down. Go back and check elementary
: chemistry, and stop making up "facts".

This is from memory, but I recall reading reports that not all
MTBE is used up in practice, due to incomplete combustion
(which occurs in just about every conventional gasoline based
motor).  Some passes through, and some is transformed
in combination with other chemicals into yet other
organic compounds, including known carcinogens.
Catalytic elements may catch some of this but not all.
Also, some card don't have catalytic elements.

Some of the byproducts have yet to be studied in detail,
or even completely identified.  They are complex
molecules, there are many of them produced,
and full studies probably aren't practical.
The chemistry is complex, not elementary, involving
organic chemical combinations at high temperatures
producing other organic chemicals, which have to be
analyzed for biological side effects, both short
and long term, direct and indirect.

A lab may be able to produce complete combustion, but
with cars, we are dealing with real world phenomena,
not lab experiments.  No amount of regulation and fines
will be enough to make cars emulate the lab environment.

Again, from memory, but don't believe me, check it
out for yourself.

-s (non-chemist but chemically "conservative")

: John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
:              | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

[ all deleted ]

Quote:
>Again, from memory, but don't believe me, check it
>out for yourself.

A modern internal combustion engine has high combustion
efficiency, thus most of the fuel is burned ( >98% ),
but it has a low thermal efficiency, meaning that it
only converts about 20-40% of the available energy
into useful work, and that's under optimal conditions
for SI engines.

But even 2% can produce a lot of undesirable products,
so various techniques, including exhaust catalysts, are
used. Oxygenate combustion emissions are different to
typical hydrocarbon combustion products in reactivity,
hence the problems determining whether oxygenates
reduce pollution.  

MTBE, like other oxygenates, is essentially pre-used
hydrocarbon fuel, but it has a high octane rating
because of the mechanisms that occur as it decomposes
and burns, so although it yields less energy per mass,
it enables engines to use conditions that improve
engine efficiency over using lower octane rating fuels.

I suggest that you obtain some of the references
on engine design and efficiency in the Gasoline FAQ
( available in rec.autos.tech or most Usenet FAQ sites ),
before posting on this topic again.

           Bruce Hamilton



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:




>:> I think you are right.  I seem to recall that MTBE burns at something
>:> like 2000 degrees F.  So no way is it burning in car engines.

(cut)

John, you are apparently referring to the adiabatic flame temperature of
burning MTBE.  If you care to research this topic a bit, you will most
likely find that the adiabatic flame temperature of normal gasoline (non
RFG) is at least this high, and probably somewhat higher.

How do I know?  Typical RFG gasoline blends contain upwards of 15 vol% MTBE.
If MTBE couldn't be burned in your auto's engine, you would see noticeable
amounts dripping out of your tailpipe!



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:





> >:> I think you are right.  I seem to recall that MTBE burns at something
> >:> like 2000 degrees F.  So no way is it burning in car engines.

> (cut)

> John, you are apparently referring to the adiabatic flame temperature of
> burning MTBE.  If you care to research this topic a bit, you will most
> likely find that the adiabatic flame temperature of normal gasoline (non
> RFG) is at least this high, and probably somewhat higher.

Please watch your attributions. I wrote none of the material to which you
replied, and I never claimed that MTBE is not consumed in car engines.
Indeed, it MUST be consumed to work, releasing its oxygen atom to oxidize
the CO (forming CO2) and then allowing the methyl and butyl radicals to
recombine into pentane--a hydrocarbon commonly found in all gasoline.

Quote:
> How do I know?  Typical RFG gasoline blends contain upwards of 15 vol% MTBE.
> If MTBE couldn't be burned in your auto's engine, you would see noticeable
> amounts dripping out of your tailpipe!

You are preaching to the wrong person.

--
John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:

> This is from memory, but I recall reading reports that not all
> MTBE is used up in practice, due to incomplete combustion
> (which occurs in just about every conventional gasoline based
> motor).  Some passes through, and some is transformed
> in combination with other chemicals into yet other
> organic compounds, including known carcinogens.
> Catalytic elements may catch some of this but not all.
> Also, some card don't have catalytic elements.

Yes, MTBE and ETBE simply trade one type of emmissions
for another. This is why I hate it when they say its
for cleaner air. Cleaner in one respect, dirtier in
others.

The oxygenate is basically there to trick the engine
into running leaner, so of course there will be left
over oxygenate.



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:

> The oxygenate is basically there to trick the engine
> into running leaner, so of course there will be left
> over oxygenate.

No, actually it is there to oxidize the CO into CO2. It works best in cars
that cannot be "tricked" (i.e. have no computerization in the engines). It
is an undesired side effect that cars with computerized combustion
controls will sense the lowered available energy and actually run richer,
lowering gas mileage.

--
John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Tue, 25 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:



>> The oxygenate is basically there to trick the engine
>> into running leaner, so of course there will be left
>> over oxygenate.

>No, actually it is there to oxidize the CO into CO2.

No. It is there to provide octane rating and it does
not, in itself oxidise CO to CO2 - a claim that you
have now made at least twice. Please don't spread
such misinformation.

From the Gasoline FAQ, available at most Usenet FAQ sites

[ begin extract ]

Oxygenates that are added to gasoline function in two ways. Firstly they
have high blending octane, and so can replace high octane aromatics
in the fuel. These aromatics are responsible for disproportionate amounts
of CO and HC exhaust emissions. This is called the "aromatic substitution
effect". Oxygenates also cause engines without sophisticated engine
management systems to move to the lean side of stoichiometry, thus reducing
emissions of CO ( 2% oxygen can reduce CO by 16% ) and HC ( 2% oxygen can
reduce HC by 10%) [17], and other researchers have observed similar
reductions also occur when oxygenates are added to reformulated gasolines
on older and newer vehicles, but have also shown that NOx levels may
increase, as also may some regulated toxins [18,19,20].

However, on vehicles with engine management systems, the fuel volume will be
increased to bring the stoichiometry back to the preferred optimum setting.
Oxygen in the fuel can not contribute energy, consequently the fuel has less
energy content. For the same efficiency and power output, more fuel has to
be burnt, and the slight improvements in combustion efficiency that
oxygenates provide on some engines usually do not completely compensate for
the oxygen.

There are huge number of chemical mechanisms involved in the pre-flame
reactions of gasoline combustion. Although both alkyl leads and oxygenates
are effective at suppressing knock, the chemical modes through which they
act are entirely different. MTBE works by retarding the progress of the low
temperature or cool-flame reactions, consuming radical species, particularly
OH radicals and producing isobutene. The isobutene in turn consumes
additional OH radicals and produces unreactive, resonantly stabilised
radicals such as allyl and methyl allyl, as well as stable species such as
allene, which resist further oxidation [21,22].

[ End extract ]

        Bruce Hamilton



Wed, 26 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:

> No. It is there to provide octane rating and it does
> not, in itself oxidise CO to CO2 - a claim that you
> have now made at least twice. Please don't spread
> such misinformation.

Did you bother to actually read what you quoted? If not, read it
again--this time for content as to why MTBE is used as an octane booster
(knock retardant) over the many other available compounds.

Note the part about reducing CO and HC emissions.

Thanks.

--
John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Wed, 26 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:


>> This is from memory, but I recall reading reports that not all
>> MTBE is used up in practice, due to incomplete combustion
>> (which occurs in just about every conventional gasoline based
>> motor).  Some passes through, and some is transformed
>> in combination with other chemicals into yet other
>> organic compounds, including known carcinogens.
>> Catalytic elements may catch some of this but not all.
>> Also, some card don't have catalytic elements.

>Yes, MTBE and ETBE simply trade one type of emmissions
>for another. This is why I hate it when they say its
>for cleaner air. Cleaner in one respect, dirtier in
>others.

Bravo!  A person who is probably not an industry insider realizes that RFG
is not the savior of mankind.


Wed, 26 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY
My sincere apologies, John.  When others have done this to me, I didn't like
it any more than you do.

I think (I'm sure I'll hear about it if I'm wrong) that I should have
attributed this to "zombie", but I may be wrong.  It is apparent to me,
after close inspection of the headers in the message below, that there was
some cutting, with little indication of such.

Quote:







>> >:> I think you are right.  I seem to recall that MTBE burns at something
>> >:> like 2000 degrees F.  So no way is it burning in car engines.

>> (cut)

>> John, you are apparently referring to the adiabatic flame temperature of
>> burning MTBE.  If you care to research this topic a bit, you will most
>> likely find that the adiabatic flame temperature of normal gasoline (non
>> RFG) is at least this high, and probably somewhat higher.

>Please watch your attributions. I wrote none of the material to which you
>replied, and I never claimed that MTBE is not consumed in car engines.
>Indeed, it MUST be consumed to work, releasing its oxygen atom to oxidize
>the CO (forming CO2) and then allowing the methyl and butyl radicals to
>recombine into pentane--a hydrocarbon commonly found in all gasoline.

>> How do I know?  Typical RFG gasoline blends contain upwards of 15 vol%
MTBE.
>> If MTBE couldn't be burned in your auto's engine, you would see
noticeable
>> amounts dripping out of your tailpipe!

>You are preaching to the wrong person.

>--
>John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
>             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407




Wed, 26 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:

> Wrong, it puts oxygen in the fuel to make sure there is excess oxygen
> pressent to better ensure complete combustion. That means lean. Notice
> how an engine meters air and fuel separately. Thusly when oxygen is
> in the fuel it is being tricked into running lean. The oxygen is in
> the cylinder at the time of combustion it doesnt oxidize the CO etc
> after combustion, it prevents the formation of the CO and there being
> left over HC by having more oxygen in the combustion chamber.

I thought that is what I said. CO is a product of incomplete combustion.
CO2 is the result of complete combustion. I never said that anything took
place AFTER combustion. Just exactly how does the excess oxygen prevent
the formation of CO if it doesn't carry the reaction to completion?
Frankly, I'm not quite sure why you are arguing with me.

Quote:
> The cars that are BEST tricked are the ones without computer controls.
> They do not have oxygen sensors to measure the additional oxygen in
> the exhaust stream and therefore run leaner. Their mixture is controlled
> by mechanical settings and thusly cannot automatically compensate.
> Computer controlled cars sense the excess oxygen and adjust by using
> a richer mixture. They do not sense 'energy' in the fuel.

You cannot "trick" something that has no logic or intelligence. If you
change the nature, amount, and ratio of reactants, you get different
products of reaction. There is no trickery about it.

--
John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Wed, 26 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:



>> No. It is there to provide octane rating and it does
>> not, in itself oxidise CO to CO2 - a claim that you
>> have now made at least twice. Please don't spread
>> such misinformation.
>Did you bother to actually read what you quoted? If not, read it
>again--this time for content as to why MTBE is used as an octane booster
>(knock retardant) over the many other available compounds.

Yes, I wrote it.

It clearly references the literature that refutes your claim that
the purpose of the oxygen in MTBE is to oxidise the CO to CO2.
None of the literature of the literature I have read makes that
claim, if you have a reference, provide it. I've provided some
in the FAQ that describe the mechanism of oxygenate additives.

The MTBE also forms species in the preflame soup that react with
other species in that soup, mostly from the hydrocarbons, and
a very small portion may react with CO, but so will other species
and oxygen sources. There are hundreds of reactions and species
proceeding in the combustion chamber and the oxygen from MTBE
is not mainly responsible for converting CO to CO2, that oxygen will
pre{*filter*}ly be supplied by the intake air. Nor does the MTBE
oxygen have a special affinity for CO, and fuel oxygenates
can also produce much higher carbonyl emissions than
hydrocarbons because they also can feed those reaction pathways.

Just because the CO emissions from a vehicle are reduced
when a fuel is modified doesn't mean that the oxygen from MTBE
effected that change. Emissions can also be reduced by changing
the hydrocarbon profile or stoichiometry alone. Making an
engine lean can reduce CO and HC, because the combustion
temperature changes ( usually increases, often creating NOx
problem, but by using oxygenates that temperature increase is
reduced ), the ratio and type of species in the soup changes, and
different reaction pathways may be followed.

MTBE was added initially added to commercial gasoline to provide
octane, in Italy in 1974. The emissions reductions were less
significant initially ( in fact several studies showed no reductions,
other than the aromatic substitution effect  - one reason why the oil
industry was initally loathe to move to oxygenates ), until the
hydrocarbon fraction was optimised to ensure the soup inside the
combustion chamber produced minimal regulated emissions.

           Bruce Hamilton    



Thu, 27 Sep 2001 03:00:00 GMT
 MTBE.... HYPOCRISY

Quote:

> Yes, I wrote it.

Ah, then it must be gospel.

Nothing like backing up yourself with yourself. The wonders of the
Internet: everyone is an expert.

--
John Higdon  |    P.O. Box 7648   | +1 408 264 4115  |      FAX:
             | San Jose, CA 95150 | +1 500 FOR-A-MOO |+1 408 264 4407



Thu, 27 Sep 2001 03:00:00 GMT
 
 [ 26 post ]  Go to page: [1] [2]

 Relevant Pages 

1. MTBE and amalgam

2. 60Minutes/MTBE/Death

3. Xanax and hypocrisy (was: Maximum dose of Xanax)

4. Pro-Tobacco Hypocrisy

5. Hypocrisy abounds among foes of medical marijuana

6. OT - Hypocrisy

7. THE PRESIDENT OF HYPOCRISY -- From the Halls of Montezuma to the Killing Fields of Iraq

8. Hypocrisy abounds in sci.psychology.psychotherapy

9. THE FAUCI FILES: Toni The Confessor's Vaccine Patent Hypocrisy


 
Powered by phpBB® Forum Software