IFE Brage (Institute for Energy Technology)
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Fischer-Tropsch synthesis over an alumina-supported cobalt catalyst in a fixed bed reactor – Effect of process parameters
Get PDFFischer-Tropsch synthesis has been investigated over a commercial type cobalt-based catalyst (20 %Co/0.5 %Re/γ-Al2O3) by varying the H2/CO ratio (2.55–1.12), CO conversion (15–75 %), reaction temperature (210 °C, 230 °C), and by adding water to the syngas. The experiments were conducted in a fixed bed reactor with the main purpose of obtaining experimental data to be used in the development and fitting of a mechanistic model. A positive effect of water on the catalyst activity was found for experiments with a H2/CO ratio higher than 1.7. Water was found to always increase the C5+ selectivity regardless of the H2/CO ratio. Increasing conversion led to increased C5+ selectivity. The selectivity to CO2 was significantly enhanced at higher conversions (high water partial pressure), particularly with the lowest H2/CO = 1.12, interpreted as the emergence of water-gas shift activity. Re-oxidation of cobalt, probably limited to small cobalt particles, is proposed as the main deactivation mechanism caused by water while a steeper deactivation curve was found for higher temperature, indicating that sintering also may play a role.publishedVersio
Spherical Micelles with Nonspherical Cores: Effect of Chain Packing on the Micellar Shape
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Interactions between Asphaltenes and a Model Demulsifier in Bulk and at an Interface Studied by Small-Angle Neutron Scattering (SANS) and Neutron Reflectometry
Get PDFThis article describes neutron reflectometry to probe the structure of the asphaltene layer adsorbed onto a hydrophilic silicon surface and the interactions between asphaltenes and a model demulsifier (pluronic). To start with, asphaltene nanoaggregation is studied in bulk by small-angle neutron scattering (SANS). In pure toluene, asphaltenes form nanoaggregates with sizes that are found to moderately increase when heptane is added. Then, the structure of the asphaltene layer onto a silicon surface is determined by neutron reflectometry. It is first shown that conclusive results on the structure of the adsorbed asphaltene layer can only be determined by varying the scattering length density of the solvent, i.e., by measuring reflectivity curves in various mixtures of D- and H-toluene and by simultaneously fitting all the data sets. The asphaltene layer can be successfully modeled using a single layer; a two-layer model always converges with the second layer having zero thickness. This layer has a thickness of 51 Å, with a low solvation close to the silicon surface (estimated ≈29%). The solvation increases with distance from the silicon oxide layer, reaching finally a value of 91%. Small-angle neutron scattering data indicate that the thickness is close to twice the radius of gyration of asphaltene nanoaggregates in solution. This result indicates that the extent of the asphaltene layer is linked to its self-associative properties in bulk. Finally, using the results obtained by contrast matching to constrain the fitting, the influence of a model demulsifier (pluronic PE 8100) on the asphaltene layer is investigated. In the presence of pluronic, the layer does not protrude as far into the bulk (thickness is reduced) and becomes rougher due to the partial incorporation of pluronic.publishedVersio
Electrical and Magnetic Behavior of GdOH Thin Films: A Search for Hydrogen Anion Superconductivity
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Potential for replacing fossil energy by local PV energy for field and transport work in Norwegian farming
Get PDFEn har i denne studien undersøkt potensialet for å erstatte fossilt drivstoff med elektrisk energi fra batterier og/eller hydrogenbrenselceller i traktorarbeidet på norske gårder. Dette ble gjort med utgangspunkt i seksten små og store modellgårder på Østlandet, i Trøndelag og i Rogaland. Disse var korngårder med og uten husdyr, og melkeproduksjonsbruk. Det årlige dieselforbruket i alle traktordrevne arbeidsoperasjoner ble beregnet og videre tidfestet og fordelt gjennom året. For alle brukstyper var det høye topper med mye traktorarbeid knyttet til pløying og/eller spredning av husdyrgjødsel om våren og til innhøsting og pløying om høsten...publishedVersio
