Silicon microreactors have been coated with mixed-metal Fe-Co Fischer-Tropsch catalysts in alumina sol-gel for conversion of syngas (CO + H 2 ) to higher alkanes. Characterization of the nanocatalysts using scanning electron microscopy, energy-dispersive X-ray, atomic force microscopy, and Brunauer-Emmett-Teller surface area measurements, packaging, and the reaction results from a mass spectrometer at controlled temperatures (200-260 °C) and pressure (1 atm) with varying H 2 :CO ratios from 1:1 to 10:1 are described. The catalyst does not adequately infiltrate the 5-µm channels; it coats nicely the 25-µm channels. The initial results are consistent with a lower conversion of CO (∼32%) in a 5-µm-channel reactor and a higher conversion (∼52%) in a 25-µm-channel reactor. The selectivity to propane (∼80%) is not affected by the width of the microchannels. The activity of the sol-gel-encapsulated catalyst before and after the reactions is estimated from its magnetic properties using a vibrating sample magnetometer.
We have been investigating conversion of syngas (CO: H 2 ) to higher alkanes [Fischer-Tropsch (F-T) Process] in 5 µm and 25 µm channel microreactors coated with sol-gel encapsulated Fe/Co-nanocatalysts. These nano-metal-catalysts were incorporated into the sol-gel matrix by two methods: 1) metal nitrate solutions; 2) metal oxide nanoparticles. Characterization of these catalysts containing Co and Fe in alumina and silica sol-gel has been carried out by several techniques. The surface area measurements by BET method show an average specific surface area of 285 m 2 /g for alumina and 300 m 2 /g for silica sol-gel encapsulated catalysts. In order to optimize the sol-gel preparation and deposition in the microchannels, the elemental composition of sol-gel encapsulated catalyst was examined by EDX. The SEM and AFM images of the reactors before and after deposition of the catalysts have also been studied. Hydrogenation-reduction efficiency of the activated Fe-Co catalysts and the level of poisoning after the reaction were estimated using a vibrating sample magnetometer (VSM). The result suggests more efficient reduction in the case of the nano-particle metal oxides compared to that derived from metal nitrate solutions. In overall, 85% of the catalyst is poisoned after 25 hrs of catalytic reaction. The surface area and the syngas conversion results indicate that silica sol-gel matrix may be a better catalyst support. For alumina sol-gel support, higher conversion of syn-gas is observed with 25 µm microreactor channels. For silica sol-gel, syngas conversion as high as 73% has been achieved by adding Ru as a promoter to the Fe/Co catalyst mixture.
Osteoblast viability, proliferation, protein expression and mineralization were studied on bare, micro-and nanoporous silicon (Si) substrates. Micro-and nano-porous-Si substrates were prepared by anodic etching of silicon in ethanolic hydrofluoric acid and characterized using scanning electron and atomic force microscopies. Mouse osteoblasts were cultured on these substrates and cellular response to these surfaces was assessed using the Live/Dead Cell Viability assay and the MTT assay for cell proliferation. Osteoblast functionality was assessed using immunohistochemistry for bone protein specific markers. Osteoblasts grew well on micro-and nanoporous silicon substrates over the twenty-one day experimental period supporting the assessment that these are suitable cell supportive surfaces. Cell proliferation rates on bare and nanoporous silicon were similar initially, however, nanoporous silicon displayed enhanced cell proliferation, in comparison to bare silicon, after 14 days in culture. Immunocytochemical assays, using bone specific markers, showed positive reactions for osteonectin and osteopontin expression on all substrates with staining intensity increasing over the 21-day experimental period. Calcium mineral deposits were quantified using the Alizarin Red histochemical assay and nanoporous silicon induced the highest level of calcium mineral production in comparison to bare and microporous silicon. The data supports the potential use of nanoporous silicon as a surface implant coating for dental and orthopedic applications. The ability to dope (and then release) drugs or growth factors from the silicon nanopores offers the potential for a multifunctional implant surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.