Ceramic / Platinum / Oxidation

[Loster]

I've searched about making a fuel cell and came across interesting stuff! ..
I'm not sure if it can be usefull in H2 production, but something makes me think that it is important .. .

Maybe it has to do with the stuff AlaskaStar was talking about . . .

Hint : .. Surface Area ..

So a car catalytic converter is made up of a Ceramic *honeycomb* plated with a platinum layer ... (- It is what I was looking for to make a fuel cell -) ..

Well to my surprise, these words reminded me of AlaskaStar talking about a special catalyser that has a large surface area ...

Ceramic Honeycomb == Large surface Area ; Ceramic == Catalyst and mentionned by Thrival I think ; Catalytic Converter == Catalytic/Oxidant process..

There are many coincidences so I had to bring it here ..

I'm not an expert in chemistry! .. I have very limited knowledge.. I know that there is an oxidation process taking place in a catalytic converter that will "burn" Nox and CO2 of the exhaust ...

An Oxidant is precisely what?! ..

Definition :

Substances that have the ability to oxidize (Commonwealth English oxidise) other substances are said to be oxidative and are known as oxidizing agents, oxidants or oxidizers. Put in another way, the oxidant removes electrons from the substance. Oxidants are usually chemical substances in high oxidation numbers (e.g. H2O2, MnO4-, CrO3, OsO4) or highly electronegative substances that can gain one or two extra electrons by oxidizing a substance (O2, O3, F2, Cl2, Br2).

What will happen if we take an electron from a mollecule of water!????

The Oxidization Catalyst
The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example:

2CO + O2 => 2CO2


I may be totally wrong with all this, hope not ..


AlaskaStar refered to a catalyst that has been used in a cell..
Ceramic is used in a PEM fuel cell ..

Solid Oxide Fuel Cells

Diagram: How a Solid Oxide Fuel Cell (SOFC) works. An AFC consists of a non-porous metal oxide electrolyte (typically zirconium oxide) sandwiched between an anode (negatively charged electrode) and a cathode (positively charged electrode). The processes that take place in the fuel cell are as follows: 1. Hydrogen fuel is channeled through field flow plates to the anode on one side of the fuel cell, while oxygen from the air is channeled to the cathode on the other side of the cell. 2. At the cathode, a catalyst causes electrons from the electrical circuit to combine with oxygen to create negatively charged oxygen ions. 3. The negatively charged oxygen ions flow through the electrolyte to the anode. 4. At the anode, the catalyst causes the hydrogen to react with the oxygen ions forming water and free electrons. 5. The negatively charged electrons cannot flow through the electrolyte to reach the positively charged cathode, so they must flow through an external circuit, forming an electrical current. 6. At the cathode, the electrons combine with oxygen to create negatively charged oxygen ions, and the process repeats.Solid oxide fuel cells (SOFCs) use a hard, non-porous ceramic compound as the electrolyte. Since the electrolyte is a solid, the cells do not have to be constructed in the plate-like configuration typical of other fuel cell types. SOFCs are expected to be around 50-60 percent efficient at converting fuel to electricity. In applications designed to capture and utilize the system's waste heat (co-generation), overall fuel use efficiencies could top 80-85 percent.

Solid oxide fuel cells operate at very high temperatures—around 1,000°C (1,830°F). High temperature operation removes the need for precious-metal catalyst, thereby reducing cost. It also allows SOFCs to reform fuels internally, which enables the use of a variety of fuels and reduces the cost associated with adding a reformer to the system.

SOFCs are also the most sulfur-resistant fuel cell type; they can tolerate several orders of magnitude more sulfur than other cell types. In addition, they are not poisoned by carbon monoxide (CO), which can even be used as fuel. This allows SOFCs to use gases made from coal.

High-temperature operation has disadvantages. It results in a slow startup and requires significant thermal shielding to retain heat and protect personnel, which may be acceptable for utility applications but not for transportation and small portable applications. The high operating temperatures also place stringent durability requirements on materials. The development of low-cost materials with high durability at cell operating temperatures is the key technical challenge facing this technology.

Scientists are currently exploring the potential for developing lower-temperature SOFCs operating at or below 800°C that have fewer durability problems and cost less. Lower-temperature SOFCs produce less electrical power, however, and stack materials that will function in this lower temperature range have not been identified.


Links .:
http://www.eere.energy.gov/hydrogenandf ... types.html
http://auto.howstuffworks.com/catalytic-converter2.htm
http://en.wikipedia.org/wiki/Redox#Oxid ... ing_agents
http://www.answers.com/topic/oxidation

[Loster]

Oh well maybe it has nothing to do with alaskastar after all ..

But still interesting ..