QNRF Newsletter Archive

From theory to practice: chemistry team shows way to more efficient gas processing

The basic nickel dithiolene unit.
A lot of preparation goes into the things we have come to take for granted as petroleum byproducts - namely, plastics. The energy-intensive methods employed to transform oil from the ground into, say, your standard disposable cup involve key chemicals called olefins, also known as alkenes.

“Olefins are incredibly important building blocks,” said Ed Brothers, Assistant Professor of Chemistry at Texas A&M University at Qatar. “In other words we build just about everything that we make out of the oil that we don’t burn from these olefins.”

Olefins, in essence, must be refined, and this process to date has cost extractors and the environment dearly.

“Between three and five percent of the world’s energy usage each year is in the refining of olefins, from petrochemical feed stocks, and what my work is focused on is coming up with a method that is much less energy intensive for the same result.”

Dr Brothers is a chemical theoretician - his work involves modeling molecules to test how they will react in different environments and in the presence of other molecules.

“If I can draw the molecule, I can predict its behavior. And so what we’ve tried to do is build from some experimental work that was done in 2006 and construct an explanation or rationalization for the behavior that has been seen experimentally,” Dr Brothers explained. “We can then modify the molecules that have been used previously to make them more friendly and efficient for the process.”

Brothers' work is a continuation of and collaboration with a well-known chemist Professor Michael Hall, of Texas A&M University in the College Station, Texas, who is also a principal investigator on the project. It also stems from early experimental findings by Wang and Stiefel — their work was “basically the starting block in the big puzzle until we got the QNRF support to look at the problem and actually put some post docs on it with some time and effort. And now we’ve resolved it. Without the QNRF funding, I don’t know that anyone would have actually had the time to investigate this and actually solve this mechanism,” Dr Brothers said.

Paraphrasing a quote by Paul Dirac, one of the founders of quantum physics, Brothers explained that every problem in chemistry is just a problem in applied mathematics. For the past 50 years, people have developed computer programs to model chemistry and very accurately portray molecules and the way that they interact.

The proposed Wang-Stiefel route.
“We took these well-developed methods and applied them to really interesting systems,” Dr Brothers said. “Basically we draw a molecule's 3D structure, and we hand it off to the computer program where it employs a series of approximations.”

The programs are able to predict molecular interactions and produce information about the physical and energetic properties of chemical interactions and structures — how they look at how much energy the reactions “cost.”

“That’s basically our investigations, because if we can find a chemical process where the energy gap between what we have now and what we would like to have to be similar to room temperature, or similar to the temperature at which the reaction takes place, we can say that it’s probable that the reaction will actually occur,” Brothers said. “We can actually get the computer to spit out real, physical chemical information — the energies, the geometries and so forth.”

Brothers and his team researched in particular how olefins bind to and are released by nickel dithiolene—the interlocking of their atoms. Through application of theory, they were able to predict the binding of the olefin to nickel and its surrounding ring structure — “for some binding motifs there’s no evidence of that existing before we did the theoretical work,” Dr Brothers said.

“Our theoretical work predicted the existence of a molecule that no experimentalist had seen, and which was subsequently found,” Dr Brothers said. “That’s the kind of stuff that makes a really good day for a theoretician.”

The team is now working to increase the efficiency to the processing of olefins — “what we are working on now is actually developing various metal containing complexes that do things similar to nickel dithiolene with respect to binding olefins, just better. And we’re hoping either this year or next year to get some experimental confirmation.”

Although the application of the team’s work is years away, Dr Brothers said that major impacts in the field of olefin processing could potentially be seen within a decade.

“It’s been a really great experience,” he said. “QNRF has been incredibly generous both to my research and TAMUQ in general. I am publishing in better journals right now in Qatar, than I was at Penn State or Rice University as a grad student and a post-doc. I was in the Journal of the American Chemical Society; JACS is the highest-impact chemical journal in the world, and we are able to get research entirely funded by QNRF in that journal. I think that is a pretty major accomplishment. So in that respect working at QNRF has been really wonderful. The generosity, the facilities and more indirectly the computational facilities that they have provided are world class.”

NPRP 08-446-1-074
Computational Investigation of the Reactions of Olefins with Nickel Dithioloenes

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