Researchers have tried to increase the efficiency of various catalyst particles by dispersing them on carbon nanofiber/nanotube (CNTs) catalyst supports, due to the availability of higher specific surface areas of these tubular carbon nanomaterials. Success has not been notably achieved. In evaluating CNTs as supports for Fischer-Tropsch catalysts, PIs Kanchan Mondal and Saikat Talapatra of Southern Illinois University and Mauricio Terrones of Pennsylvania State University observed that the CNTs themselves perform better than conventional catalysts, exhibiting an order of magnitude more activity with three orders of magnitude less iron content. It was thought that this was due to some uniqueness in the residual iron from the CNT synthesis, but subsequent extraction of the residual Fe resulted in still another order of magnitude improvement in activity. This is a potentially dramatic change in the nature of CNT catalysis. One of the aims of this proposal is to investigate the role of CNTs themselves as catalysts in heterogeneous catalysis, especially FT catalysis. Other significant factors such as their curved carbon surfaces (offering higher adsorption potential to the adsorbate gases near its vicinity), surface defects and functionalization have been primarily over looked as to their possible contribution to heterogeneous catalysis. The PIs propound an excellent series of questions related to catalysis on CNTs that they intend to address, and to then creatively adjust synthesis and treatment processes to optimize the CNT catalytic performance.
The educational aspects of this project are interesting in that the undergraduate and graduate students will be exposed to a truly cross-cutting and multi-disciplinary research effort about the use of nanommaterials in heterogeneous catalysis. The potential tie-in to renewable fuels and energy is an added plus in the educational experience.
The key research goals of this multidisciplinary collaborative research were to understand the catalytic characteristics of as-produced CNTs. Acting as excellent catalysts for FT synthesis, and to design targeted synthetic routes to enhance these characteristics that would result in an activity enhancement of this new breed of catalyst for FT synthesis. In particular, we were able to: a) synthesize various architectures of CNTs with selected surface properties: b) discover strategic ways to functionalize these CNT architectures selected species for enhancing and maximizing the FT synthesis activity? c) systematically investigate the physical and chemical properties of the CNT catalyst surface? d) correlate the surface properties with the obtained activity towards CO conversion and product spectrum during FT synthesis? e) theoretical investigations of the effect of surface properties – curvature, functional groups, defects, metal sites, etc. on the activity of CNTs towards CO hydrogenation. Presentations of the research and publications were published. In addition to the research activities, the project was also successful in the broad impact since we organized summer activities each year together with the Penn State MRSEC program. The Terrones group organized a modules on "Graphene and Carbon Nanotubes" during the Science Leadership Camps at Penn State in which High School Students participated. In addition, the project co-supported REU students working in the Terrones group in which URM actively participated.
