Sustainable Chemistry and Engineering
Moderator: Wayne Ranbom, Director of Research and Development, Arkema, Inc.
Speakers: Elizabeth Papish, Assistant Professor and Graduate Advisor, Department of Chemistry, Drexel University
Brian Mullen, Principal Scientist, Segetis
Ivan Dmochowski, Associate Professor, Department of Chemistry, University of Pennsylvania
As sustainability becomes an economic necessity, fundamentally new chemical pathways must be developed using green and sustainable chemistry and engineering to minimize environmental impact. Following the principle of “better to prevent waste rather than clean up after,” researchers are developing new processes and products, as well as improving catalytic selectivity and efficiency in chemical reactions (which also provides cost savings).
Innovation Day 2011, Photograph by Conrad Erb
The 2011 breakout session on Sustainable Chemistry and Engineering approached the topic using three very different examples, though one theme in particular, biomimicry, threaded through each presentation. Presenters addressed questions about what we can learn from nature, how we can mimic biological processes, and how these processes can help save energy, reduce risk, and expand our applications for organic chemistry.
Elizabeth Papish, from the Department of Chemistry at Drexel University, reviewed her team’s current organometallic green-chemistry projects and anticipated research directions. The overall thrust is an attempt to mimic processes occurring in nature. The group studies the structure and function of important metalloenzymes, with an emphasis on catalysis, to form products with less energy input. They have focused on two of nature’s most common reactions: water oxidation and hydrogenation. In regard to water oxidation the team has had some success with placing iridium compounds in the ligands. Reactions are carried out in methanol—water solvent under mild conditions.
In reference to hydrogenation Papish discussed a number of model reactions under study in academic laboratories. One model in nature involves bacteria that produce hydrogen from organic compounds. She presented crystallographic data on several catalysts where metal ligand structures were modified to change electron density. An important objective is producing hydrogen with significantly lower energy input. Papish closed by stressing the important role experimentation plays in making new discoveries.
The session’s second speaker, Brian Mullen, gave an overview of the work currently pursued by his green-chemistry company, Segetis. Over the past few years at Segetis the interest has been on building new molecules from levulinic acid. Levulinic acid is of interest because it provides a new platform for creating levulinic ketals. The acid is itself a platform molecule from which many different derivatives can be created. Drawing on research done by the company’s founder, Segetis looked at the top twelve bio-based materials derived from nature and sought to translate those materials to the field of organic chemistry. Interested in making sure the company’s research included an adequate energy balance, Mullen described Segetis’s use of life-cycle analysis as a means to determine how much mass and energy are used from start to finish; results are often expressed as gallons of gasoline saved. For every gallon of product they make, Segetis saves two gallons of gas in terms of energy. In addition, for every ton of Segetis product the company saves seven tons of CO2 equivalence. Also of interest to Segetis is the registration of its products through the Toxic Substances Control Act and the REACH inventories for regulatory purposes. Segetis researchers have performed toxicology testing to assess risk to human health, such as carcinogenicity, aquatic toxicity, and eye and skin irritation. Mullen is confident based on the test results that they are succeeding in Segetis’s mission to design safer chemicals.
The session’s third speaker, Ivan Dmochowski, is a professor of chemistry at the University of Pennsylvania and is associated with its Penn Park Initiative. He began his remarks by noting the current blossoming of synthetic chemistry’s ability to control the assembly of molecules on the very small scale. Again, researchers have been looking to biological systems for answers, though bio-nanotechnology is still developing. There is a definite interest in discovering and understanding the transformations carried out in biological systems; according to a recent paper by David MacMillan (Princeton University) published in Nature, organic chemists are now able to synthesize small quantities of any known natural product given sufficient time and resources, though of course access to those resources is the ongoing challenge.
Dmochowski discussed the relationship between nanotechnology and energy consumption and conservation, where the nano fabrication processes used by the semiconductor industry are notoriously inefficient. He used the example of the desktop computer, which consumes four times more energy in its production than in the next few years when it sits on the desk. These realities provide the motivation to create low-tech fabrication processes, an area in which important advances have occurred in the last ten or so years.
Dmochowski went on to discuss how current problems can be approached through the development of new nano particles. He described several initiatives under way in Penn labs that might control feature sizes on nano particles:
- functionalizing proteins and binding nano particles to develop complex structures;
- making nano particles more bio-friendly by cloaking them in proteins;
- using vesicles for delivery of therapeutics;
- using bio-friendly porphyrins for drug delivery; and
- further pursuit of a project in the physics department to develop a $1,000 genome (the project involves passing DNA through specifically designed nanopores to determine molecular structure).
Dmochowski closed by stressing the current multidisciplinary nature of discovery. Collaboration, he said, is needed to bridge many of the gaps between disciplines.