Assessing blame -- Prius catalytic converter theft

Indeed. And you notice CO₂, because it's the same stuff you exhale, and a high concentration of it makes you feel the air is stuffy and want to leave.

We haven't evolved to notice CO the same way. You don't see it or smell it or taste it, and you do turn kinda pink when it binds to your hemoglobin, but that's too late.

But my point was, this claim got made in this thread:

... and I don't think that's accurate. Even without any catalytic converter, most of what comes out of the engine is already CO₂ and H₂O. The catalyst is there to take care of what isn't.

 

7.1: Catalytic Converters - Chemistry LibreTexts.

 

It would be nice to hear what the percentages are of each. Do you have a resource that can help?

 

Nope.
If I wanted to foster a G2 or G3 from another state, I would just use a < $100 bolt-on solution and get on with my life.
Catco Catalytic Converters 2516 Catco Universal-Fit Catalytic Converters | Summit Racing

I live in a medium-small sized county (1000 mi2) with less than 60,000 souls aboard.
Our next human caused "bad air" day will be our first.
There are over 3100 counties in the US, and most of them look more like my county rather than those that have to worry about 'air quality.'
Remember.....LESS than 50 counties in the US have more than 1,000,000 souls.

If we accept the argument that the anthropogenic component of climate change is significant enough to risk government involvement, that's a different argument, isn't it?
How do catalytic converters mitigate AGW?

In other words.....
This is a 'local' thing.
If you can bolt a $100 onto a G2 or a G3 and meet federal emissions standards on free soil?
DO THAT.

Quite frankly?
I think that the most worthwhile thing that a $100 cat will do is to extinguish the CEL - and for that, it's probably worth it at the price.
Remember.
We're talking about freekin Priuses, not some 3/4 tonne, barely muffled trucks needing a ring job.
THAT'S WHY I stand by my assertion that most G2s and G3s inadequately maintained as they tend to be, will meet fairly measured federal minimums with a test pipe.
IYKYK.....

 

Indirectly as the Lambda self-tuning keeps the engine tuned close to an optimum fuel-air mixture. The improved efficiency reduces the AGW output per unit of fuel.

I well remember the previous technology, carburetors, and black arts needed to keep them working.

Bob Wilson

 

Carburetors are as far removed from modern closed-loop fuel injected engines as a flinch-lock musket is from an AGM-114 (Hellfire) missile, and that's an aside.
What does all of this have to do with OEM versus "federally compliant" catalytic converters??

 

I would prefer to see a formal study that measures the OEM vs compliant part performance. I've not followed the inspection technology but wonder if 'inspection' exhaust analyzers have enough fidelity to measure the relative effectiveness?

But mine is a casual curiosity as I no longer have a catalytic converter. Just bad air from local traffic with bad emissions.

Bob Wilson

 

Diesel and Gasoline Engine Exhausts - Diesel and Gasoline Engine Exhausts and Some Nitroarenes - NCBI Bookshelf

The major products of the complete combustion of petroleum-based fuels in an internal combustion engine are carbon dioxide (13%) and water (13%), with nitrogen from air comprising most (73%) of the remaining exhaust. A very small portion of the nitrogen is converted to nitrogen oxides and some nitrated hydrocarbons. Some excess oxygen may be emitted, depending on the operating conditions of the engine. Gasoline engines are designed to operate at a nearly stoichiometric ratio (air:fuel ratio, ≃14.6:1); diesel engines operate with excess air (air:fuel ratio, ≃25–30:1; Lassiter & Milby, 1978).

Incomplete combustion results in the emission of carbon monoxide, unburnt fuel and lubricating oil (Yamaki et al., 1986) and of oxidation and nitration products of the fuel and lubricating oil. These incomplete combustion products comprise thousands of chemical components present in the gas and particulate phases (Zaebst et al., 1988); some specific chemical species and classes found in engine exhausts are listed in Table 1. The concentration of a chemical species in vehicle exhaust is a function of several factors, including engine type, engine operating conditions, fuel and lubricating oil composition and emission control system (Johnson, 1988).​

The 13% CO₂ and 13% H₂O, with the 73% N, add up to 99%.

Table 3 in the reference above breaks down the remaining 1% of yucky stuff, some of which the catalyst mops up.

In this reference linked earlier,

7.1: Catalytic Converters - Chemistry LibreTexts

the money quote was here: "Without catalytic converters, vehicles release hydrocarbons, carbon monoxide, and nitrogen oxide." The quote is true—it's saying vehicles release those things, and they do—it's just not saying those are the only things coming out of the engine. Those are the things in the small fraction that's not already CO₂ and H₂O and N, because that small fraction accounts for all the worst human health and smog impacts, and is what the catalytic converter is there to mop up.

These days, it bears mentioning that the CO₂ that is already 13% of what's coming out of the engine, and that the catalyst turns some of the other stuff into more of, while benign in direct impact on human health, no longer seems quite so benign with climate taken into account.

 

For me, the money quote was a word in the second sentence, underlined for emphasis here:

"A catalytic converter is a device used to reduce the emissions from an internal combustion engine (used in most modern day automobiles and vehicles). Not enough oxygen is available to oxidize the carbon fuel in these engines completely into carbon dioxide and water; ..."

I.e. there is plenty of CO2 and H2O before the cat, but the fuel conversion to those is just not compete.

==================

The cat doesn't contribute to an engine's thermodynamic efficiency. If the combustion chamber was releasing just CO and HC, not any CO2 and H2O, I don't see how it is even theoretically possible to be achieving the 40% efficiencies that modern engines are reaching.

 

The Clean Air Act initially called for a 90% reduction of emissions, that is pollutants, from new cars. Tier 1 regulations went into affect later than 1975, so they are likely result in a greater reduction, but its values is what I found.

The total hydrocarbon limit was 0.41 g/mile back then. Assuming that value is set at 10% of what a nonregulated car emitted, the pre-emission control car was emitting 4.1 g/mile out the tailpipe. The CO limit was 3.4 g/mile, leading 34 g/mile non controlled. About 16 grams of that is carbon.

That's 20.1 g/mile of material from gasoline that didn't under go complete combustion to water and CO2. A car getting 15 to 20 mpg is using 140 to 190 grams of gas per mile.
Timeline of Major Accomplishments in Transportation, Air Pollution, and Climate Change | US EPA
https://dieselnet.com/standards/us/ld_t1.php

A catalytic convertor does not help much with global warming. Carbon burned in a car is going into the air. The cat is there to reduce the emissions that are immediately harmful. Some of those do have more warming potential than CO2. Methane is amoung the HC emissions, N2O is more than ten times as potent as methane. The cat helps by reducing the amount of those.
https://en.wikipedia.org/wiki/Global_warming_potential

 

Well heck I'm cutting my cat out then

 

I think your pee is around 95% water also, and only a few percent of stuff worth removing. So it's probably ok to cut out those kidneys too.

 

. . . replacing it with an after market 'cat' and selling the OEM part.

In your case, I approve. But I don't have a dog in that fight.

Bob Wilson

 

Oh no! Now we have gone and done it….

Why keep the cat?

“Carbon monoxide has 210 times greater affinity for haemoglobin than oxygen.”

from:

Carbon monoxide poisoning - PMC

Interesting tidbit, if I’m not mistaken:

CO2 has a greater affinity to hemoglobin than O2.

What does this all mean, clean air is IMPORTANT!

Don’t have the bright idea of buying O2 tanks, high concentrations of O2 can stop autonomic breathing. (We need our air just right. That’s right, pure O2 can kill you)…

 

Sadly I haven't found an aftermarket cat that can keep the Money Indicated Light off. Advice?