Fischer-Tropsch Synthesis Catalyzed by Nano-Sized Iron. NATHAN HOULD (State University of New York - Stony Brook Stony Brook, NY 11793) DEVINDER MAHAJAN (Brookhaven National Laboratory, Upton, NY, 11973)

The Fischer-Tropsch (F-T) reaction is used commercially to synthesize clean liquid hydrocarbon fuels from synthesis gas (syngas). Syngas is a mixture consisting primarily of CO and H2 produced by coal gasification or steam reforming of natural gas (>90% CH4). The F-T syngas conversion is achieved with catalysts based on Fe, Co, and Ru. The aim of this project was to evaluate a nano-sized catalyst to ameliorate the prevalent problems with the F-T synthesis, those being low space time yield and product selectivity. This research utilized nano-particles of iron oxide (a-Fe2O3) to drive the F-T reaction and collected data to yield fundamental insight into the process mechanism. Catalyst phase and morphology and the subsequent reaction product slate and fractional conversion were comparatively analyzed to develop a superior F-T process. The catalyst was evaluated in the slurry phase at 0.73 MPa and 493 K with a custom built continuous flow process unit. This unit consisted of a 1 liter constant stirred tank reactor (CSTR) and had provisions for gas, liquid and slurry sampling. The product slate was analyzed with chromatographic methods developed to quantitatively identify aliphatic C5-C10 liquid hydrocarbons, C1-C5 gaseous hydrocarbons products, C1-C6 alcohols, and CO, H2, O2, N2, and CO2 gases. Analysis employing these methods was used to determine the extent of reaction and showed the nano-particles (3nm MPD) have a propensity to yield paraffins; the liquid phase products consisted of >30% C10+ hydrocarbons. Gas phase analysis shows that methane was 0.24% of reactor effluent and C2-C5 gaseous hydrocarbons were each <0.1% of reactor effluent. Mössbauer data were used to identify the phase of the catalyst. The initial phase of the catalyst was a-Fe2O3 and the quenched catalyst phase was a mixture of oxides and carbides that was predominantly magnetite (Fe3O4). It follows that the active catalyst phase is magnetite or the remaining carbide phase is highly active. A more detailed catalyst material analysis was conducted with transmission and scanning electron microscopy. Ultimately, this research shows F-T synthesis is subject to conversion constraints via pressure; therefore, the F-T process should be run at pressures >0.825Mpa to scale up to an advanced F-T process.

Resolving Electromigratory Issues Via Nanomaterial Implementations. CHRISTOPHER NACHMIAS (Georgia Institute of Technology Atlanta, GA 30332) ARLENE WU ZHANG (Brookhaven National Laboratory, Upton, NY, 11973)

Electromigration affects almost all integrated circuit and microelectronic device design, production, and functionality. This phenomenon occurs due to an overwhelming amount of current density passing through increasingly smaller conducting vias which comprise electronic devices. Causing cracks and voids in the connections and severely hindering operation, electromigration will continue to limit the various performance aspects of electronic devices unless a solution is realized. One such solution may be the use of nanotechnology, whether it is the popular nanotubes or emerging nanowires, in devices to curb the effects of electromigration. Nanotubes and nanowires have exhibited extraordinary conductive and electrical properties which make them a promising alternative to common copper and silicon devices today, despite some difficulties with utilizing these materials. Several materials were utilized to study and interpret the situation of electromigration issues at present and the possible implementation of nanomaterials. Extensive use of the proceedings within varying scientific and technological conferences discussing nanomaterials and microelectronic device fabrication were observed and analyzed. In accordance to these references, several online periodicals relating to the research field were observed as this is a developing technology and breakthroughs occur daily. Finally, discussion with others directly related to the research fields was conducted. Through the research, it was observed that, as stated previously, nanotubes and nanowires present themselves as viable alternatives to present microelectronic vias. Various methods exist to develop these materials, however harnessing their full capability is yet to have been achieved. Such considerations as the chemical orientation of these materials, their functional lifetime, and fabrication concerns are issues that are still open for further exploration and must be examined. It is clear that ultimately, to some extent some of the current means toward microelectronic circuit fabrication and development will have to progress in another direction due to limitations presented by electromigratory issues. The failure of the devices due to these issues is at the root of nanomaterial research and exploration to other alternatives as well. The benefits of using nanomaterials are overwhelming, however overcoming inherent difficulties associated with them may limit their time toward fruition as a common place implementation in the field.

Template-Assisted Chemical Vapor Deposition (CVD) Growth of Carbon Nanotubes. STEVEN MUI (Columbia University New York, NY 10027) STANISLAUS WONG (Brookhaven National Laboratory, Upton, NY, 11973)

Carbon Nanotubes (CNTs), which are composed of cylindrical layers of graphene, can exhibit novel mechanical and electronic properties depending on their diameter, chirality, and assembly. In order to understand the potential functions and applications of carbon nanotubes that extend to both physical and biological sciences, fabricating a variety of carbon nanotube structures becomes necessary. Using the chemical vapor deposition (CVD) method with an alumina template, various gases, and catalysts, we can produce a number of CNT types, which can then be analyzed with a number of microscopic and spectroscopic techniques. In particular, we are interested in fabricating multi-walled carbon nanotubes (MWNTs). Using an alumina membrane that was placed in tube furnace, a gas mixture of 30% ethylene and 70% helium, heated at 670 C, was flowed over a 6h period to form MWNTs in the nanoscale pores of an alumina template. The alumina template was dissolved by immersing the membrane in 10M NaOH solution followed by centrifugation to remove the NaOH. The nanotubes were characterized by different microscopic and spectroscopic techiques, including SEM,TEM,AFM,UV-Vis and FTIR. The analyses show the presence of MWNTs as well as single walled nanotubes (SWNTs). Further purification protocols are necessary before additional forms of analysis can be used to verify the presence of MWNTs as well as single-walled carbon nanotubes (SWNTs). This work, involving the fabrication of a variety of CNT structural motifs, will contribute to further research involving electronic and biological applications of composite nanomaterials.

Weight Predictions for Infiltrated Kernel Nuclear Fuel. LINDA BLAKE (Seattle Pacific University Seattle, WA 98119) LYNNE ECKER (Brookhaven National Laboratory, Upton, NY, 11973)

Abstract Weight Predictions for Infiltrated Kernel Nuclear Fuel. LINDA BLAKE (Seattle Pacific University, Seattle, WA 98119) LYNNE ECKER (Brookhaven National Lab, Upton, NY 11973). Nuclear fuel capable of operating at higher temperatures will be vital for the next generation of nuclear reactors. Infiltrated Kernel Nuclear Fuel (IKNF) consists of graphite kernels infiltrated with uranium and coated with alternating carbon-containing layers to protect the kernel and contain fission products. For IKNF to be a viable process for a manufacturing facility, one needs to be able to control the amount of fuel in the kernels. Currently, Brookhaven has laboratory notebooks from previous IKNF experiments and is interested in completing development of the fuel fabrication technique. The purpose of this research was to review, develop, and verify a model that can be used to predict the weight gain (uranium loading) during the IKNF process. Data was extracted from the lab notebooks from the previous experiment and compared to the values obtained by a model. Also, experimental parameters were varied in order to determine which variables impact the uranium loading. The model correctly predicts trends in the data. Predictions for weight gain from the model were compared to the experimental data and found to match, or follow closely, the raw data curves. However, there are still unknown parameters that may significantly impact the quantitative predictions. Once new experimental data is available, the unknown parameters can be accounted for and integrated into the models. The ability to predict the weight gain contains numerous advantages. By controlling the number of infiltrations, one can control the amount of fuel in the kernels. It was demonstrated that enough uranium was infiltrated into the graphite that a viable commercial fuel was obtained. Also, the density control allows for ample space to remain available in the kernel to retain fission products. IKNF properties make it an excellent option for the VHTR. The developed models will assist in the next stages of this research.