Hier ein paar Infos zu aktuellen und möglichen zukünftigen Anwendungen bzw. Eigenschaften. Aus den ersten Links geht hervor, dass es aktuell keine Alternative zu Rhodium gibt, um die Stickstoffemissionen eines Autos deutlich zu reduzieren (Teslafahrer sind da anderer Meinung), in europäischen Städten ist der Verkehr für 50-75% der Stickstoffbelastungen verantwortlich, moderne Katalysatoren bringen -90% NOx:
http://www.easterncatalytic.com/education/tech-tips/catalyst-basics-platinum-palladium-...
Rhodium, currently the most expensive of the three, has by far the highest activity for the removal of NOx from the exhaust. In addition, it has significant activity for the oxidation of HC and CO and very good resistance to the poisons present in the exhaust stream. Its primary drawback is its high cost.
Most catalytic converters today consist of some combination of palladium and rhodium. With current precious metal prices, this gives a good trade-off between cost and performance. While efforts continue to find cheaper alternatives to the precious metals, the tightening aftermarket and OEM emission standards make it likely that they will remain the key components of catalytic converters in the future.
http://www.sciencedirect.com/science/article/pii/S0926337303002698
From the experiments, it was concluded that a combination of platinum and rhodium is required to achieve good NOx storage and reduction performance.
http://www.ncbi.nlm.nih.gov/books/NBK100035/#!po=6.57895
Today's catalytic converters still contain some rhodium, because, as Lambert said, there is no acceptable substitute for rhodium when it comes to NOx reduction.
https://en.m.wikipedia.org/wiki/Rhodium
http://www.tandfonline.com/doi/abs/10.1080/01614949408009468
Rhodium shows some advantages over the other platinum metals in the reduction of nitrogen oxides to nitrogen and oxygen.
https://de.m.wikipedia.org/wiki/Rhodium
Die wichtigsten Anwendungsbereiche des Rhodiums sind Fahrzeugkatalysatoren. Es dient darin als Katalysator zur Reduktion von Stickstoffmonoxid zu elementarem Stickstoff. Würde stattdessen Platin oder Palladium eingesetzt, würden verstärkt Ammoniak und Distickstoffmonoxid entstehen.
Hier Infos zu weiteren Anwendungsmöglichkeiten:
http://www.erneuerbareenergien.de/neue-brennstoffzelle-wandelt-alkohole-und-zucker-in-c...
Anders als die etablierten Alkohol-Brennstoffzellen arbeitet die metallorganische Brennstoffzelle (organometallic fuel cell, OMFC) nach einem völlig anderen Prinzip - mit einem speziellen molekularen Komplex des Metalls Rhodium, der als Anoden-Katalysator fungiert.
http://www.rsc.org/chemistryworld/2013/04/solar-concentrator-syngas-methane-power-stati...
US researchers are developing a system that could boost the efficiency of gas-fired power plants while reducing their greenhouse emissions. The device use solar energy to convert methane into more energy rich syngas, thereby allowing power plants to use around 20% less natural gas to produce the same amount of electricity.
...
The solar concentrator produces high temperatures that drives the reaction of steam and methane flowing inside the microchannels into syngas – a mixture of carbon monoxide and hydrogen. A rhodium catalyst reduces the activation energy and speeds up this reaction.
...
He also envisages further applications including for manufacturing facilities that combust natural gas in order to produce process heat, and processing facilities that utilise syngas for other purposes, such as the production of synthetic transportation fuels.
http://pubs.acs.org/doi/abs/10.1021/am405293e
Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region.
http://www.hindawi.com/journals/jnm/2014/287493/
The Rhodium doped TiO2/HCP exhibited enhanced photocatalytic activity and can be considered as a potential photocatalyst in wastewater treatment.
Noch ein Überblick zu den Eigenschaften:
http://www.lenntech.com/periodic/elements/rh.htm
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2933823/
Recently, several Rh and Ru complexes have been shown to exhibit oxygen-independent
light-induced anticancer activity. For example, Barton et al. have shown that several
octahedral RhIII complexes with extended diimine ligands, bind only weakly to
DNA in the absence of light but on photoactivation bind to DNA and cleave the DNA
backbone with high specificity for mismatched DNA.
Aus 2013, ca. 85% des Angebots geht in Katalysatoren:
http://www.forbes.com/sites/kitconews/2013/07/25/focus-rhodium-slides-due-to-ample-supp...
...last fall, Honda Motor Co. said it developed a new auto catalyst that reduces rhodium use by 50% and was using it in its 2013 Accord, with the technology to be sequentially adapted to other Honda models as well.
Haben wir Chemiker an Bord, die sich beruflich damit beschäftigen?
Beste Grüße,
Jens