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The cost of CO2 mitigation for the chemical industry is not small. I was struck by your earlier comments about some of the oxidative reactions using air. You pointed out that in reaction with butane, you have to avoid the explosive limit, and you can produce a lot of CO2 by accident if you don't avoid the combustion limits. Have you thought about using carbon dioxide-oxygen mixtures rather than air in these kinds of reactions?

Leo Manzer: CO2 often is recycled in some of these processes. It is not specifically mixing CO2 and oxygen. That will change the flammability envelope significantly, I think. We have not done this. It may be an opportunity for somebody to look at.

Olaf Walter, Forschungszentrum Karlsruhe (Germany): Oxidations are always a target for increasing selectivity. In recent years, there also have been investigations using microreactors for heterogeneous oxidations, which may increase selectivity, often by avoiding hot spots on the catalysts.

A second technique, also in the same direction, might be the use of supercooling carbon dioxide as a solvent, where you have a one-phase system in the oxidation. This is then a homogeneous reaction, and a catalyst may not be needed. I think we should point out that there is the potential of still further optimization of these processes.

Richard Alkire, University of Illinois: It is very exciting to hear of the need for new chemistry and also new processing. In chemical engineering at least, that has dropped away from the academic side over the years. In my opinion, in the earlier part of the century, chemical engineers in academics actually participated in the invention of new processes. When I think of the deemphasis over the years on the academic side coupled with the reduced industrial research investment, it seems to me that there is the potential for a serious disconnect which may already exist. If I think of trying to do chemical engineering as running across the street at any other university, I can imagine having difficulty engaging in conversation that might be helpful in the way you suggest is needed.

Yet you have mentioned certain research areas in which academics could make contributions. Could you say exactly what the interesting chemistry or engineering is that is needed here? Also, do you have any thoughts on how to engage that part in a useful way?

Leo Manzer: First, you have to have funding available in both chemistry and chemical engineering so that you have enough people available to discuss things with each other. This is the most important part of the process. Consider DuPont's work on the oxidation of butane to maleic anhydride. We worked on this for 15 years. In that situation, chemistry and chemical engineering were completely integrated with folks constantly talking together.

The engineering aspects of running an oxidation reactor in an anaerobic mode like that with lots of butane around, was very complicated. This is one of the biggest issues. If people actually do look at developing some of these other processes, it is scale-up that will be most difficult. The scale issues are incredibly complicated. There is a real opportunity where the funding is available for engineers and chemists to get together to work jointly on these projects. I don't know how to make this happen except to have money available to support your research programs and those of others. I mean, without the people there to do the research, it will never happen.

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