The Division of Chemistry supports David Rogow of the University of California - Berkeley as an American Competitiveness in Chemistry Fellow. Dr. Rogow will work with Prof. Jeffrey Long to synthesize a series of metal-organic framework (MOF) materials using high-throughput synthesis methods. In particular, the research will focus on developing materials which can efficiently and selectively adsorb carbon dioxide. In addition, materials will be incorporated into polymer membranes for development of MOF/polymer composite membranes for gas processing applications. Additional work will be carried out in collaboration with scientists at the Advanced Light Source of the Lawrence Berkeley National Laboratory, to conduct in-situ, x-ray diffraction studies of these materials, in order to explore the details of the ways in which carbon dioxide is incorporated into these materials. For his plan for broadening participation, the PI will work with at-risk youth in an area Job Corps Program (Treasure Island Job Corps) as well as other Job Corps programs on the West Coast (San Jose, Wolf Creek, Tongue Point, and others).
Research like that of Dr. Rogow is aimed at developing better materials for carbon dioxide removal from gas streams. Results from research like that supported here will lead to better methods for carbon dioxide separation and removal, which can significantly impact efforts at reducing the emission of carbon dioxide into the atmosphere. The efforts at broadening participation being pursued by Dr. Rogow are aimed at encouraging young people, especially those from groups underrepresented in the sciences, to consider pursuing higher education in science and technology areas.
Carbon dioxide (CO2) is recognized as the most important greenhouse gas; although it has less global warming potential compared with other gases such as methane, it is released in the greatest amount, number of sources and frequency, since it is the major end product of combustion. Globally, the vast majority of our energy comes from the combustion of fossil fuels. One strategy that could greatly reduce the amount of CO2 released into the atmosphere is to trap the CO2 from large stationary point sources such as the smokestacks of coal-fired electricity generation plants followed by sequestration in geological formations. The current technology that is closest to implementation in industry for applications in selective CO2 absorption is based on aqueous amine solutions. While highly selective for CO2, these solutions are prone to degradation and so have a limited cycle life. They also require large amounts of thermal energy to remove the absorbed CO2 and regenerate the material to its absorbent state, since new chemical bonds between CO2 and amines are formed upon absorption. Other materials that may offer advantages over amines include porous solids such as zeolites and activated carbons. Higher chemical and thermal stability, as well as lower energy requirements for regeneration, make solid porous materials attractive alternatives to the amine solutions. The nature of the gases interacting with the internal surfaces of porous solids is also different; it is termed adsorption since it is not a chemical reaction, as with amines, but a physical attraction to the chemical environment on the pore wall surfaces of the material. Metal-organic frameworks (MOFs) are a new class of highly porous solid materials composed of metal nodes connected by organic linker molecules. The beauty in MOF chemistry is the ability of the synthetic chemist to select the different structural components and thereby tailor the properties of the material to the intended application. In this context, MOFs can be tuned to be selective for CO2 by installing chemical groups on the internal surfaces of the material that interact attractively with CO2. In this work, MOFs containing amine groups on the pore walls were designed, where the amine groups were tethered to the organic linker molecule prior to synthesis of the MOFs. The design also allows for so called "open metal sites" in the MOFs, which interact strongly with CO2, polarizing the molecule and binding it to these sites. These features have been shown to increase the selectivity of a MOF for CO2 over other gases in a flue gas mixture, which mostly consists of nitrogen (N2), which is not very polarizable, along with much smaller amounts of oxygen, water vapor, and various trace gases. Work at the Advanced Light Source (ALS), a particle accelerator that produces high-intensity X-rays, at Lawrence Berkeley National Laboratory (LBNL), the partner organization in this program, focused on the commissioning of a new experimental setup that makes it possible to observe gas molecules inside of the MOF structures by X-ray crystallography. The observation of CO2 and other gases interacting with the open metal sites in MOFs are of particular interest. These experiments provide detailed information about the physical forces that lead to strong binding interactions, including bond distances, angles, and chemical composition. The insights gained from these experiments are expected to lead to the design of new MOFs that will show ideal performance as CO2 capture materials. In order to encourage economically disadvantaged and at risk young people to pursue higher education, in particular Science Technology Engineering and Mathematics (STEM) fields, presentations were given to students in the Job Corps program. The focus of the talks was the experience of the PI during and after attending the Job Corps program, and how that help eventually led to earning a PhD in chemistry. Also discussed were the statistics of minorities in Science, Technology, Engineering and mathematics (STEM) fields and how the numbers do not represent the percentage of those demographics in society; that this means essentially that we are missing out on a large talent pool here in the US. Information about scholarships, local colleges and universities, and how to get started in higher education, was provided for the students.
