Inside a small, neat lab, tucked away inside the engineering building at Rutgers University in New Jersey, a researcher is trying to use cheap and renewable sources in order to upgrade them to new useful products and fuels.
Prof. George Tsilomelekis, Ph.D, is a chemical engineer. He’s been working with several spectroscopic techniques for the past 15 years, particularly vibrational spectroscopy. That includes both Raman, and infrared spectroscopy.
His job is to understand how molecules interact with each other, but most importantly how molecules interact with surfaces. His studies focus primarily on how these surfaces (catalysts) can upgrade these molecules to something more valuable with end-use.
Tsilomelekis is an Assistant Professor of Chemical and Biochemical Engineering. Among the projects he oversees relates to the conversion and upgrade of cheap biomass. In particular, his focus is on using non-edible biomass that does not compete with food resources in an effort to produce bio-based chemicals and fuels in an economic efficient manner.
To do this he uses catalysts, substances that aid chemical reactions. These materials provide the required functionality (active sites) that promotes chemical reactions but also can have high surface areas through pores to help “accommodate” all the different molecules resulting from the biomass.
“Through a rational design of these catalytic materials, we can convert these molecules to useful chemicals, to value-added chemicals,” he said. “It can be a solvent, a fuel, or just a fuel additive that can improve the quality of existing fuels. It can also be a polymer precursor.”
Right now, the world relies on getting most of these materials from petroleum and many times, this requires energy-intensive processes.
“What we really tried to do is to use alternative and renewable sources such as biomass or natural gas” he said. “For instance, natural gas contains a lot of methane but also ethane, propane etc.” Imagine, Tsilomelekis said, if you could take methane and upgrade it to value-added chemicals. “The shale gas revolution during the last years, provide a great opportunity to use these very cheap natural gas sources. This can be a game changer in the field and now we can use these raw materials to explore new research avenues towards getting all the important compounds that we usually get from petroleum.”
“What I'm working right now is to use ethane and propane (components of natural gas) and upgrade it to ethylene and propylene,” he said.
His goal is to take these cheap raw sources and upgrade them through interactions with catalysts to products that are more valuable.
Back in 2002, his instructors would talk about chemical reactions and reactors, but he wanted to understand them in first place to design them better.
“What I always wanted to do is to understand exactly what is happening inside the catalytic reactors,” he said. “So, spectroscopy for me is my eyes and my senses inside the reactors. I'm trying to see what are the fundamental steps during a catalytic reaction. If I see it, I know how it works. And if I know how it works, I can go back and modify the catalytic material the way that I want. This will help me get better materials or design better materials with better properties.”
Tsilomelekis is from Greece, a small village at the base of a mountain range. A pronounced Greek accent accompanies his fluent English. His thick black hair is pulled back in a bun, and he sits in front of a large flat screen monitor. It’s better for viewing spectra.
What Tsilomelekis is working on is pure basic research. But hopefully someday it will be adopted on a large scale by industry to make more energy efficient processes towards the production of value-added products.
Spectroscopy plays a fundamental role essentially as a “sensor” to understand the individual steps involved in all these chemical processes. One step can be as simple as measuring the concentration of a compound in solution and as complex as understanding the interaction of molecules with surface sites inside pores in a very fast manner. The first can tell us for instance how glucose is depleted inside a bioreactor during a metabolic reaction. The second is more relevant to catalysis but we have to combine it with other techniques.
To study these catalytic reactions, Tsilomelekis utilizes more than one spectroscopic techniques.
“We have, for instance, Raman spectroscopy or infrared spectroscopy that can give us information about the structural changes of this material,” he said. “But at the same time, we measure the product distribution with other analytical techniques, like gas chromatography or mass spectrometry. This is the field of Operando spectroscopy where materials are investigated under real operating conditions. When we combine these, we can build structure-reactivity relationships, which means now that I see how the material changes during reaction. Then, we look whether these changes are correlated with better product distribution or better product yields.”
Tsilomelekis’ go-to instrument in his lab is a HORIBA LabRAM HR Evolution, a confocal Raman microscope that lets him observe catalytic reaction via measuring vibrational spectra.
“Now I can screen many different catalysts very, very fast,” he said. “And then I can find which catalyst is best or how I can modify them to be more selective. I can even now get information on how to change the reaction conditions based on this fundamental understanding to avoid for catalyst deactivation”
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