[barsikjal]

http://www.gizmag.com/noxcat-catalys...m_medium=email

Diesel engines are a classic example of good news and bad news. The good news is that diesel engines are much more fuel efficient than petrol engines. The bad news is that they belch out some pretty nasty emissions like nitric oxide and nitrogen dioxide. The good news is that catalytic converters can scrub those out. The bad news is that last Friday the platinum needed by the converters is selling for US$1,473.10 an ounce. Now the good news is that a team at Nanostellar in Redwood, California, has developed a mineral catalyst that outperforms platinum at a fraction of the cost.
Platinum is an excellent catalyst, though it does have a few problems. One of the biggest at the moment is that a violent labor dispute in South Africa sent the price skyrocketing. Also, with the World Health Organization classifying diesel exhaust as a carcinogen, the potential demand for platinum for catalytic converters for hundred of millions of vehicles far outstrips supply. The Nanostellar team, led by Dr. Kyeongjae “K.J.” Cho, professor of materials science and engineering and physics at UT Dallas and co-founder of Nanostellar, determined that a mineral catalyst would be a cheaper alternative.

<font color="#333333">Reporting their findings in the August 17 issue of Science, Cho relates that computer modelling showed that mullite was a cost-effective substitute. Mullite is a silicate mineral discovered on the Isle of Mull, Scotland in 1924. It’s rare in nature, but a synthetic version is produced commercially for use in various porcelains, such as crucibles and heating balls. It has a very high melting point of 1840 C (3344 F) and as a mixed-phase oxide mineral it makes a very attractive catalyst. In addition, laboratory tests indicate that converters using mullite would have 45 percent lower emissions than with platinum.

[TpDoctorOneTp]

Interesting news, thanks for that.

[mortgrhhh]

Mullite

Interestingly it can also be found at Burning Mountain Wingan as a result of the fire remelting Kaolin clays.

Pulled straight from Wikipedia (the source of all information)

Mullite is present in the form of needles in porcelain.

It is produced artificially during various melting and firing processes, and is used as a refractory material, due to its high melting point of 1840°C.

In 2006 researchers at University College London and Cardiff University discovered that potters in the Hesse region of Germany since the late Middle Ages had used mullite in the manufacture of a type of crucible (known as Hessian crucibles), that were renowned for enabling alchemists to heat their crucibles to very high temperatures.

The formula for making it (using kaolinitic clay and then firing it at temperatures above 1100 °C) was kept a closely guarded secret.

Mullite morphology also is important for its application. in this case, there are two common morphologies for mullite. One is a platelet shape with low aspect ratio and the second is a needle shape with high aspect ratio. If the needle shape mullite can form in a ceramic body during sintering, it has an effect on both the mechanical and physical properties by increasing the mechanical strength and thermal shock resistance. The most important condition relates to ceramic chemical composition. If the silica and alumina ratio with low basic materials such as sodium and calcium is adjusted, the needle shape mullite forms at about 1400 °C and the needles will interlock. This mechanical interlocking causes the porcelain to have high mechanical strength.

So. Cheap, easily made from plentiful raw materials, already manufactured, sounds good.

[Abraham]

With 45% more efficiency, what would the difference in global diesel emissions become?
45% less, presumably.

[Psymoussy]

Someone more intelligent and a better scientist and/or teacher than I am could explain how to look more than just superficially at the popular press and track the sources to the actual findings report, but I am none of those so all I'll talk about is the reference and its abstract.


DOI: 10.1126/science.1225091

Mixed-Phase Oxide Catalyst Based on Mn-Mullite (Sm, Gd)Mn2O5 for NO Oxidation in Diesel Exhaust

Oxidation of nitric oxide (NO) for subsequent efficient reduction in selective catalytic reduction or lean NOx trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used platinum (Pt)–based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn2O5 are an efficient substitute for the current commercial Pt-based catalysts. Under laboratory-simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability, and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120°C with conversion maxima of ~45% higher than that achieved with Pt. Density functional theory and diffuse reflectance infrared Fourier transform spectroscopy provide insights into the NO-to-NO2 reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.

[offinoNem]

45% less, presumably.

didn't think that out at all, did I?

[drislerfottor]

Interesting reading. Thanks.

[oranowdenda]

http://www.transportation.anl.gov/en..._catalyst.html

"Another type of technology is ammonia-selective catalytic reduction, using a material called urea as the ammonia source," Marshall said. "Ammonia is toxic, and unless all of it is converted during the process, whatever remains could be released to the atmosphere. While some European diesel manufacturers are taking the urea approach, U.S. diesel manufacturers are looking for alternatives." Since a system using the new catalyst would not require an onboard urea storage tank and uses the onboard diesel fuel as the reductive material, the new catalyst is considered safer and more energy-efficient.

[rXpX]

> The bad news is that they belch out some pretty nasty emissions like nitric oxide and nitrogen dioxide

By appropriate choice of combustion conditions, it's possible to avoid both VOCs and oxides of nitrogen in diesel engines. My understanding is that these are now no longer a problem in the latest diesels.

> With 45% more efficiency, what would the difference in global diesel emissions become?

Not 45% less, 0% less. This is a difference in capital cost, nothing to do with quality of emissions.

[unlomarma]

> The bad news is that they belch out some pretty nasty emissions like nitric oxide and nitrogen dioxide

By appropriate choice of combustion conditions, it's possible to avoid both VOCs and oxides of nitrogen in diesel engines. My understanding is that these are now no longer a problem in the latest diesels.

> With 45% more efficiency, what would the difference in global diesel emissions become?

Not 45% less, 0% less. This is a difference in capital cost, nothing to do with quality of emissions.

Well that's not what they said:

In addition, laboratory tests indicate that converters using mullite would have 45 percent lower emissions than with platinum.

[Pa33anger]

Ah, but does that statement refer to quality of emissions though,

[mtvlover571]

For many years diesels have had the luxury of being able to emit large quantities of NOx and particulate (Black smoke). They are now having to reduce diesel particulate and NOx to almost immeasurable levels. The Diesel particulate has been reduced to almost nothing with the addition of a diesel particulate soot trap incorperated into the exhaust system.

The NOx is the hard one. There are a variety of ways they are trying to deal with this. One of the most common methods is to keep the combustion temperatures below 1371°C where NOx form. This can be achieved by recycling exhaust gasses into the combustion chamber, quenching the combustion temperatures. This has always been a problem due to the large amount of carbon build-up in the intake manifold and the engine. Another common method is to inject “Add-Blue” (Urea) into the exhaust.

This breaks down into ammonia before entering a “Selective Catalyst Reduction” converter where the NOx is almost eliminated. Before this however the exhaust gasses still pass through a catalytic converter to reduce the NOx as much as possible. The cost of these has always been an issue due to the cost of Platinum Palladium and Rhodium. There has been a black market for these converters where the converters are removed from the vehicles and sold for their precious metals.

I was under the impression that this new catalyst would be more cost effective than the conventional converters allowing them to be larger and possibly reducing the amount of “Add Blue” which is about 4% in comparison to the diesel burnt.

[LsrSRVxR]

For many years diesels have had the luxury of being able to emit large quantities of NOx and particulate (Black smoke). They are now having to reduce diesel particulate and NOx to almost immeasurable levels. The Diesel particulate has been reduced to almost nothing with the addition of a diesel particulate soot trap incorperated into the exhaust system.

The NOx is the hard one. There are a variety of ways they are trying to deal with this. One of the most common methods is to keep the combustion temperatures below 1371°C where NOx form. This can be achieved by recycling exhaust gasses into the combustion chamber, quenching the combustion temperatures. This has always been a problem due to the large amount of carbon build-up in the intake manifold and the engine. Another common method is to inject “Add-Blue” (Urea) into the exhaust.

This breaks down into ammonia before entering a “Selective Catalyst Reduction” converter where the NOx is almost eliminated. Before this however the exhaust gasses still pass through a catalytic converter to reduce the NOx as much as possible. The cost of these has always been an issue due to the cost of Platinum Palladium and Rhodium. There has been a black market for these converters where the converters are removed from the vehicles and sold for their precious metals.

I was under the impression that this new catalyst would be more cost effective than the conventional converters allowing them to be larger and possibly reducing the amount of “Add Blue” which is about 4% in comparison to the diesel burnt.

FWIW it's 'Adblue' and it's not very good.

[KaterinaNJq]

FWIW it's 'Adblue' and it's not very good.

OK, thanks Bill