Saturday, August 25, 2007

Oxidation and fuel combustion burning catalyst

There is a good catalyst for diesel fuels which supports complete burning and what more, it works better in environment containing water vapour, and even better for us, it consumes (reduces) any nitrogen oxides it finds! It is Ceric Oxide CeO2.

It can be bought in industrial quantities in China and in Canada, the Canadians have few interesting things, like Ceric oxide with Surface area = 70-90 m3/g - or even better nanometric powder with particle pize: D50 = 10~100 nm. That surely is interesting.

The chinese site has Ceric Oxide ground for optical glass polishing, like CERIMAX 1003 - 0.6-5.0 micron powder or even better (it's not that bad to be used in certain nozzle types) .

What could be interesting is Cerium Chloride. Cerium requires only low activation energy for most reactions, like 150-250°C and Cerium Chloride is soluble in water. I thing that mixing Cerium chloride with ammonium nitrate could lead to rapid decomposition and perharps a detonation even at low total mass of the nitrate. You should be very careful and wash your hands before working with ammonium nitrate not to bring even Cerium traces into it! The last thing you could possibly want is to have ammonium nitrate that has a tendency to decompose!

In USA you can buy Ceric oxide here, as a polishing agent, price 49$ per kilogram! If you want ceric oxide particles of the right size and premixed into diesel fuel, buy ENVIROX which is designed exactly for use in diesel fuels.

In Europe, you canj buy Cerium oxide at UKGE they are rather cheap and have other polishing and grinding media too. I can recommend anyone to view the annopowders under microscopes here at Kemco International as they have some very fine catalyst powder with bulk density of 0.25grams/cm3! That is 28.4 times less than solid a piece. Surface area is 55 - 95 m2/g among the highest. Their complete nanomaterials list is here. [a note: imagine a small glass full of this powder - only 3.5% of it is the ceric oxide, the rest is air. If you pour fuel over it, you get close to 100% 'coverage' with only 3.5% of CeO2 content by volume. It means the aggregates have good distribution of their active surface, not located in certain 'hotspots'. When properly used, this kind of catalyst may prove the most effective one, because it is most evenly distributed. High-temperature gasoline engines which produce a lot of nitrous oxides would be happy to have this catalyst in their fuel. Well, the DDR (East Germany of communist era) used them (illegally?) in their racing cars and won some competitions too :) Not sure if they used any nano-technology as we call it today, but just a little catalyst adds a lot in efficiency.]

The last company to mention is NanoScale, their Ceric oxide is here. It is not as perfect catalyst as the one from Kemco, but they have a complete pricelist online and you can order directly with a credit card! They ARE costly but it is nice to have 500 square meters of surface area in one gram of TiO2!

Another nanoparticle 'megashop': NanoArmor, great catalog.

Did I forget Engis(uk) Ltd? Oh yeah, the offer the finest non-nano ceric oxide polishing powder. It is Unicer 636 - You have to contact them by e-mail here, they sell it in 1 or 25kg packings. The Unicer 636 has "AVERAGE PARTICLE SIZE 0.6 – 0.7 μm". This is good for forming polishing slurries, because the powder does not separate fast, or at all. For mixing into liquid fuels it is very useful - passes trough the fuel filters! But I would still hesitate to mix it into solution of sugar and KNO3. But in case it would not self-incinerate during processing, it would give the second best result after the nanopowders.

I may post a fourth update to this article later.

Fourth update!

I dug up important information about many catalysts on a chinese university webpage.
It is a list of NOx decomposition catalysts sorted by their activity. This should serve as an additive aid to catalyst consideration, since CeO2 serves as a carbon "burninator" too. By combining some catalysts together we may get fast-burning solid substances that would hardly burn without the catalysts!

For rocket motor, I would like to try nano-powder of CeO2 plus some ordinary powder of Cu2O. The copper(IV) oxide might add instability and rapid pressure growth (lots of released oxygen), so my theory is to balance it with CeO2 so that it will burn the carbohydrate fuel evenly.

Nitrous Oxide Catalysts

List of reported N2O decomposition catalysts exceeds 200. [1-33]

According to Amphlett [3], the activity of metal oxides for nitrous oxide decomposition decreases in the following order:

CoO > CuO > NiO > MgO > Ce2O > CaO > BeO > Al2O3 > ZnO > TiO2, Fe2O3

According to Trapnell [4], the results of activity of metal oxides for nitrous oxide decomposition reported by three different groups in the following order:

CuO > MgO > Al2O3 > ZnO > CdO > TiO2 > Cr2O3 > Fe2O3 (by Schwab and co-wokers)

CoO > CuO > NiO > MgO > CeO2 > CaO > Al2O3 > ZnO > Fe2O3 (Schmid and Keller)

Cu2O > CuO > ZnO > Cr2O3 (by Dell, Stone and Tiley)

According to Clark [5], the activity of metal oxides for nitrous oxide decomposition decreases in the following order:

Cu2O > CoO > Mn2O3 > NiO > CuO > MgO > CaO > Ce2O > Al2O3 > ZnO > CdO > TiO2 > Cr2O3 > Fe2O3 > Ga2O3

According to Kapteijn the activity of zeolite catalysts decreases in the following order [6]:

Rh, Ru > Pd > Cu > Co > Fe > Pt > Ni > Mn

Plainly exciting, some scientists claim "The preparation and activity of copper zinc oxide catalysts for ambient temperature carbon monoxide oxidation". Carbon monoxide burning at room temperature. Well, we might add a bit of the zinc oxide to the catalyst too. (In car engines this is very important, in rocket science a bit less)

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