Dragomir B. Bukur

Fischer–Tropsch Synthesis: Differences Observed in Local Atomic Structure and Selectivity with Pd Compared to Typical Promoters (Pt, Re, Ru) of Co/Al2O3 Catalysts

Pd was examined as a promoter for Fischer–Tropsch synthesis, and its effects on cobalt oxide reduction and product selectivities relative to commonly used promoters (i.e., Pt, Re, and Ru) at atomically equivalent levels were compared. Pd was identified to promote cobalt oxide reduction to even lower temperatures than Pt and Ru. However, Pd addition deleteriously affected product selectivity, and a clear shift to favor light products was observed. XANES analysis of an activated model catalyst revealed that Pd was in the reduced state. Local atomic structure was examined by EXAFS. Unlike Pt, Re, and Ru promoters, where previous investigations by groups such as Dr. Guczi’s and ours have only observed coordination of the promoter with cobalt, Pd displayed both direct coordination to Co as well as other Pd atoms. The results suggest that this feature may be responsible for the measurably higher light gas selectivities observed.

Miniaturized calorimeter for thermal screening of energetic materials

The use of chip-scale calorimeters for research and development has increased during the last two decades. The high sensitivity of these devices allows their use for characterization of very small amounts of sample. However, the potential for using them for screening of highly energetic materials (i.e., explosives) has not been fully explored. In this paper, we present the design aspects of two chip-scale calorimeter prototypes based on thick silicon membranes for liquid and solid thermal characterizations. The ultimate goal of the proposed work is to produce a portable calorimeter that can be incorporated as a new approach for detection of highly energetic materials such as explosives based on the information obtained from the calorimeter. The concept of this application is that indirect detection via the determination of thermal energy released in exothermic reactions can be detected by chip-scale calorimetric sensors. Details about the calorimeter design using finite element analysis are presented along with the fabrication procedure of the proposed sensor. Finally, preliminary results that provide experimental validation of the device design are presented.

Modeling of Fischer-tropsch Product Distribution over Fe-based Catalyst

Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst Branislav Todic, Tomasz Olewski, Nikola Nikacevic, Dragomir B. Bukur* a Chemical Engineering Program, Texas A&M University at Qatar, PO Box 23874, Doha, Qatar b Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, Belgrade, Serbia c Artie McFerrin Department of Chemical Engineering, Texas A&M University, 3122 TAMU, College Station, TX 77843, USA dragomir.bukur@qatar.tamu.edu