By Gary Thomas
A new Metal Organic Framework has been created that could potentially revolutionise the process of refining gasoline, which could in turn lower gas prices at the pump.
Exciting new family
Metal Organic Frameworks (MOFs) are an exciting new family of materials that are
crystalline compounds of metal ions linked to rigid organic molecules, creating a stable porous structure – a little like a sponge with microscopic holes.
Different organic molecules and metals give rise to different pore sizes and shapes, meaning the properties of the material can be altered. Potential uses for MOFs include catalysis, gas storage and, in this case, gas separation.
High octane gasolines
Gasoline, or petrol, is a common fraction of crude oil and is best known across the world as fuel for cars. Premium blends of gas are predominantly high octane gasolines, and tend to cost more than regular gas.
Costly and time consuming
The reason for this higher price is that the molecules used for the premium blends are harder to separate out.
The issue arises because some high octane isomers have very similar boiling points to low octane isomers, meaning that the separation of gasoline via heating can be relatively costly and time-consuming.
High-octane gas has its benefits, but due to the difficulties in seperating hydrocarbon isomers, it is often relatively expensive.
The newly synthesized material offers an alternative route. Due to its chemical formula of Fe2(bdp)3, the structure of the MOF is such that the when gasoline is passed through the material, the lowest-octane isomers are not allowed through, sticking to the side of the material like wet paper.
I asked Matt Hudson, Postdoctoral fellow at the NIST Center for Neutron Research (NCNR), to sum up how the MOF can stop low-octane isomers.
(It is) Physical adsorption (binding) between the low-octane isomers and MOF" said Hudson "but at energies much lower than chemical bonds which makes it cycleable."
The key benefits of the new material, according to Hudson, are "Large energy and cost savings versus cryogenic distillation separations as this separates HCs at higher temperatures" and "Much better Low vs. High octane separation potential than current separations via Zeolite 5A."
The team working on the project included scientists from the National Institute of Standards and Technology (NIST) and other leading Universities.
The material itself was first synthesized in the laboratory of Jeffrey Long, professor of chemistry at the University of California, Berkeley.
Separate research was conducted at the NIST Center for Neutron Research (NCNR) using neutron powder diffraction to understand why the MOF had the right structure for the job.
About the potential benefits of the new material, Matthew Hudson a postdoctoral fellow at the NCNR said: "It's easier to separate the isomers with higher octane ratings this way rather than with the standard method, making it more efficient."
"And based on the lower temperatures needed, it's also far less energy-intensive, meaning it should be less expensive."
The findings have been published in the May 24th 2013 edition of the journal Science.
A move away from energy-intensive refining
As the work on this new material is still at a research stage, there are a lot of steps that must be taken before it can be commercialized. For instance, whether the material can be produced on a large scale remains to be seen.
Furthermore, the cost of integrating this new technology into operational refineries needs to be weighed against the benefits of doing so.
However, in essence a move away from energy-intensive oil refining process can only be a good thing in the long run, both environmentally and economically.
Original Source: National Institute of Standards and Technology (NIST)