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Ding K.,University of California at Santa Barbara | Zhang A.,Gas Reaction Technologies Inc. | Stucky G.D.,University of California at Santa Barbara
ACS Catalysis | Year: 2012

Propane oxidative dehydrogenation is a promising candidate for on-purpose propylene production. However, in oxidative dehydrogenation the propylene yield is limited by the simultaneous oxidization of propane to multiple oxygenated byproducts. We show that a small amount of I 2 is highly effective in catalyzing the dehydrogenation of propane into propylene, using dibromomethane (DBM), a byproduct of the activation of methane by bromine, as the oxidant. Single-pass "C 3H 6+C 3H 7X" (X = Br, I; C 3H 7X can be easily converted to C 3H 6 and HX) yields of up to 80% can be easily achieved, with the highly selective conversion of DBM to methyl bromide, which is readily converted into either high-market-value petrochemicals or liquid fuels. Bearing in mind that the formation of DBM is one of the major undesirable byproducts in the bromine-mediated gas-to-liquid technology, our findings create a win-win situation. On the one hand, this approach is promising for developing a low-cost, on-purpose propylene technology using natural gas as a feedstock. On the other hand, DBM is shown to be a useful reactant for the industrial application of the bromine-mediated gas-to-liquid technology. © 2012 American Chemical Society. Source

Ding C.,University of California at Santa Barbara | Soni G.,University of California at Santa Barbara | Bozorgi P.,University of California at Santa Barbara | Piorek B.D.,SpectraFluidics Inc. | And 3 more authors.
Journal of Microelectromechanical Systems | Year: 2010

A novel 3 cm ×3 cm × 600μm-thick Ti-based flat heat pipe is developed for Thermal Ground Plane (TGP) applications. The Ti-based heat pipe architecture is constructed by laser welding two microfabricated titanium substrates to form a hermetically sealed vapor chamber. The scalable heat pipes' flat geometry facilitates contact with planar heat sources, such as microprocessor chip surfaces, thereby reducing thermal contact resistance and improving system packaging. Fluid transport is driven by the wicking structure in the TGP, which consists of an array of Ti pillars that are microfabricated from a titanium substrate using recently developed high-aspect-ratio Ti processing techniques. The hydrophilic nature of the Ti pillars is increased further by growing ∼200-nm hairlike nanostructured titania of the pillar surfaces. The resulting super hydrophilic wick offers the potential to generate high wicking velocities of ∼27.5 mm/s over distances of 2 mm. The experimental wetting results show a diffusive spreading behavior that is predicted by Washburn dynamics. The maximum effective thermal conductivity of a heat pipe is directly related to the speed of capillary flow of the working fluid through the wick and is measured experimentally in the first-generation device to be k = 350W/mċK. A dummy TGP with a cavity volume of ∼170μL was used to test the hermiticity level of the laser packaging technique. The device gave a 0.067% of water loss based on ∼60μL of charged water at 100 °C in air for over a year. © 2010 IEEE. Source

Ding K.,University of California at Santa Barbara | Derk A.R.,University of California at Santa Barbara | Zhang A.,Gas Reaction Technologies Inc. | Hu Z.,University of California at Santa Barbara | And 4 more authors.
ACS Catalysis | Year: 2012

CH 3Br, like CH 3OH in the Methanol-To-Gasoline process, can be readily directly converted to petrochemicals and liquid fuels. CH 3Br can be obtained in high yields by the direct bromination of methane using relatively low reaction temperatures and pressure, but with the formation of dibromomethane (DBM) as a primary side product. Here, we report that DBM can be highly selectively converted to higher hydrocarbons and methyl bromide via a catalytic hydrodebromination process. Silica-supported palladium carbide shows a high selectivity for the conversion of DBM to higher hydrocarbons, mainly light olefins. Silica-supported ruthenium has a high selectivity for the conversion of DBM to methyl bromide, which can then be converted to fuels or light olefins. These reactions offer pathways to increase the overall useful product yield of the methane bromination reaction, thus taking an important step toward the potential industrial application of bromine mediated Gas-To-Liquid technology. © 2012 American Chemical Society. Source

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