Most modern kitchen ovens are "self cleaning" but if you are old enough, you may remember ovens that did not have this feature, and which required lots of scrubbing, often with caustic - hopefully if you know someone who used to do this they wore gloves, as I recall my mother doing when I was a child. It was a very messy business, oven cleaning, and I would imagine that a good many people were actually injured doing it.
Aren't we lucky, with all our swell new technology.
The way self cleaning ovens work is that they are coated with ceria, which is CeO2, the oxide of a lanthanide metal.
The lanthanide metals are of increasing economic importance owing to the bourgeois wind power/hybrid car/electric car fantasy that has become so popular as we push ourselves toward oblivion, with 2011 promising to be a record year for dangerous fossil fuel waste dumping in Earth's atmosphere, despite all that wonderful stuff we hear about the wind power/hybrid car/electric car fantasy.
(There isn't, by the way, enough neodymium - another lanthanide - on the planet to make this fantasy any more real than a ride at Disneyland, but don't worry, be happy.)
Happily for those might have otherwise felt the need to hire someone to clean their ovens, cerium is one of the more common lanthanides, and we are in no danger of a shortage of self cleaning ovens, although it is possible we will face a shortage of dangerous natural gas and electricity to run the ovens.
Anyhow. The paper from the primary scientific literature I will discuss tonight in this brief throwaway diary - which I leave for myself as a kind of "sticky note," and not because it will otherwise mean a hill of beans - is in the relatively new journal, a Wiley publication, ChemSusChem, which is dedicated to sustainable chemistry.
Here's the abstract and a link to the article if you have access to a subscribing library:
Ceria as a Thermochemical Reaction Medium for Selectively Generating Syn Gas or Methane from Water or Carbon Dioxide.
By the way, this scheme does not for the record violate the second law of thermodynamics. It requires significant heat, which the author's claim - playing to popular delusion "could" come from solar thermal energy reactors.
It won't. Nothing will happen except ever increasing dangerous fossil fuel waste dumping. It's over. We're cooked.
As for the journal itself, there is no such thing as "sustainable" by the way, since humanity will get what it deserves, owing to its rapid embrace - the link is just one example out of many - fear, ignorance and superstition.
(Um...um...um...no, Virginia, 35S is, um, not a fission product. One of the fun things that anti-nukes like to do is to point up their ignorance right in the text, although this doesn't prevent other ignorant people from believing them. Sometimes reading this stuff is like watching a TV show with Pat Robertson explaining the origins of the universe.)
Anyway, here's some excerpts from the paper:
To enable the transition away from a fossil-fuel-based energy economy, it is essential to address, in addition to energy extraction from sustainable resources, the problem of energy storage. We pursue in this work a storage strategy that relies on the capacity of selected nonstoichiometric metal oxides to uptake and release oxygen. Specifically, doped cerium oxide (ceria), a relatively abundant material,[1] is cycled between MO2 and MO2-δ (where M represents both cerium and the dopant) using thermal energy as the input, ideally derived from solar heating, and the changes in oxidation state are utilized to produce a chemical fuel...
There will be no "transition away from a fossil-fuel-based economy, by the way, not while there are still rocks to frack, and not before this planet's atmosphere begins to uncomfortably resemble that of the Venutian atmosphere.
But to continue with the paper:
We demonstrate not only H2 generation by this strategy, but also direct and rapid production of high-energy-density fuels compatible with the existing energy infrastructure. In particular, we selectively generate syngas (CO+H2 ; a chemical feedstock that can be converted to liquid fuels) using CO2 in addition to H2O as inputs, and, when the ceria is treated with a base-metal catalyst, we directly produce CH4. Beyond fuel generation, the effective conversion of CO2 into useful chemical
feedstocks represents a potential carbon mitigation strategy.
Here's a description of the material they used:
We selected 15% samarium-doped ceria (SDC) to serve as a test-bed for ceria-based fuel production, because the thermodynamics of reduction are well characterized.[16] Hence, the value of oxygen nonstoichiometry, δ, in the chemical formula Sm0.15Ce0.85O1.925 - δ is known for a given temperature and oxygen partial pressure. We examined the fuel production halfcycle using porous SDC, pretreated at 1500 8C for 24h, to simulate possible deactivation resulting from sintering and then lightly reduced the material to a specified δ, value (typically 0.05 for experimental convenience).
The authors were able to produce syn gas of a particularly desirable composition, 2:1 H2 to CO at 13.1% thermal efficiency.
We're saved!
Just kidding...
Have a nice day tomorrow.