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Distributed hydrogen generation from liquid fuels has attracted increasing attention in the past years. Petroleum-derived fuels with already existing infrastructure benefit from high volumetric and gravimetric energy densities, making them an interesting option for cost competitive decentralized hydrogen production.In the present study, direct steam reforming of diesel and diesel blends (7 vol.% biodiesel) is investigated at various operating conditions using a proprietary precious metal catalyst. The experimental results show a detrimental effect of low catalyst inlet temperatures and high feed mass flow rates on catalyst activity. Moreover, tests with a desulfurized diesel–biodiesel blend indicate improved long-term performance of the precious metal catalyst. By using deeply desulfurized diesel (1.6 ppmw sulfur), applying a high catalyst inlet temperature (>800 °C), a high steam-to-carbon ratio (S/C = 5) and a low feed mass flow per open area of catalyst (11 g/h cm2), a stable product gas composition close to chemical equilibrium was achieved over 100 h on stream. Catalyst deactivation was not observed.

Sewage sludge can be disposed of by fermentation, incineration or gasification. Conversion of the resulting biogas, combustion heat or gasification gas into electricity is often employed. Since sewage sludge cannot be fermented completely and due to the significant heat requirements for drying it in the incineration plant or before the gasifier, the electrical output in all cases is very low. Consequently, this work seeks to investigate a combination of fermentation and gasification in which dried fermentation waste is converted in a gasifier. With the aim of combining these two biomass conversion processes with power generation in an efficient manner, a hybrid system consisting of a SOFC and a gas turbine is investigated. This combination of a biogas plant and a gasifier has the advantage that waste heat can be used as a heat source in drying the fermentation waste. Another advantage is the combined conversion of biogas and gasification gas in the SOFC. As steam from gasification gas is used for internal reforming of methane out of biogas at the anode of the SOFC, the complexity of the plant is reduced and the efficiency is increased. A configuration including a pressurized gasification process was identified as most efficient in terms of electrical output.

The partial catalytic dehydrogenation has been carried out with defined model components and model mixtures representing hydrocarbon groups and chemical composition of desulfurized Jet A-1 over 1.0 wt% Pt/Sn catalyst on γ-Al2O3 carrier. The hydrogen yield, cracking products and carbon deposit on the catalyst surface are studied in order to define suitable reaction conditions for a pressurized auxiliary power unit concept with gas conditioning for fuel cell systems. The results show that alkanes lead to high cracking rate and carbon deposit which can be suppressed with increased pressure up to 8 bar. The hydrocarbon group cycloalkanes represented by methylcyclohexane shows sufficient conversion of 32 wt% towards hydrogen evolution in model mixtures under pressurized conditions. The average hydrogen yield of the model mixture of 72 nl H 2 /kgfeed was achieved under defined reaction conditions of 425 °C catalyst bed temperature, 8 bar system pressure and 4 s of contact time on the catalyst.

Recently, liquid biofuels have attracted increasing attention as renewable feedstock for hydrogen production in the transport sector. Since the lack of hydrogen infrastructure and distribution poses an obstacle for the introduction of fuel cell vehicles to the market, it is reasonable to consider using liquid biofuels for on-board or on-site hydrogen generation. Biodiesel offers the advantage of being an environmentally friendly resource while also having high gravimetric and volumetric energy density.The present study constitutes an experimental investigation of biodiesel steam reforming, the main emphasis of which is placed on finding optimum operating conditions in order to avoid catalyst deactivation. Temperature was varied from 600 °C to 800 °C, pressure from 1 bar to 5 bar and the molar steam-to-carbon ratio from 3 to 5. Based on the experimental results, coke formation and sintering are identified as the main deactivation mechanisms. Initiation of catalyst deactivation primarily depends on catalyst inlet temperature and feed mass flow per open area of catalyst. By using a metallic based precious metal catalyst, applying low feed flow rates (31 g/h∙cm2) and a sufficiently high catalyst inlet temperature (>750 °C) coking can be minimized, thus avoiding catalyst deactivation. A stable product gas composition close to chemical equilibrium has been achieved over 100 h with a biodiesel conversion rate of 99%.

Fractionation of kerosene by rectification leads to fuel fractions characterized by different proportions of iso-paraffins, n -paraffins, cyclic, dicyclic, aromatics and diaromatics. Fractions of progressively higher boiling point range are characterized by progressively higher average carbon chain length, as well as increasing content of sulfur containing molecules. Three fractions, corresponding to 5, 14 and 32 wt.% of the original kerosene and having boiling point ranges 140–150 °C; 150–160 °C; 160–170 °CM, respectively, containing predominantly C 8 –C 9 , C 9 –C 10 and C 10 , respectively, and 4, 12 and 24 ppm sulfur, respectively, were fed to a partial dehydrogenation reactor using a Pt–Sn/BaO–γ–Al 2 O 3 catalyst. A hydrogen productivity increase up to a factor 3 for the low-boiling point fraction compared to the original kerosene is observed. The catalyst durability is significantly increased due to lower sulfur and coke deposition on the catalyst for the low boiling point fraction. The fractionation of kerosene Jet A-1 fuel by rectification is a promising approach for the enhancement of durable hydrogen generation via partial dehydrogenation.

A new concept is proposed for combined fermentation (two-stage high-load fermenter) and gasification (two-stage fluidised bed gasifier with CO2 separation) of sewage sludge and wood, and the subsequent utilisation of the biogenic gases in a hybrid power plant, consisting of a solid oxide fuel cell and a gas turbine. The development and optimisation of the important processes of the new concept (fermentation, gasification, utilisation) are reported in detail. For the gas production, process parameters were experimentally and numerically investigated to achieve high conversion rates of biomass. For the product gas utilisation, important combustion properties (laminar flame speed, ignition delay time) were analysed numerically to evaluate machinery operation (reliability, emissions). Furthermore, the coupling of the processes was numerically analysed and optimised by means of integration of heat and mass flows. The high, simulated electrical efficiency of 42% including the conversion of raw biomass is promising for future power generation by biomass.

Vergleich hinsichtlich Kohlenstoffumsatz, energetischer Effizienz und Wasserstoffbedarf für verschiedene Biomass-to-Liquid-Prozesse jeweils mit und ohne Einsatz von zusätzlichem Wasserstoff aus erneuerbaren Energien.

Der Flugverkehr ist auf Energietrager mit einer hohen Energiedichte angewiesen, diese bieten vor allem flussige Kraftstoffe. Dafur ist die Konzeptionierung und Bewertung von nachhaltigen Herstellungsverfahren synthetischer Kraftstoffe notwendig. Als innovativer Ansatz wird ein „Power-to-Liquid“ Prozess analysiert, bei dem Synthesegas uber die reverse Wasser-Gas-Shift-Reaktion aus Elektrolysewasserstoff und CO2 generiert wird. Das Synthesegas wird im folgenden Fischer-Tropsch-Prozessschritt zu flussigen Kohlenwasserstoffen synthetisiert, die anschliesend zur Herstellung definierter Fraktionen aufbereitet werden. Die Prozessschritte werden zu einem Gesamtprozess verknupft und mittels Prozesssimulation in Aspen Plus abgebildet. Dabei wird zuerst eine Technologiestudie durchgefuhrt und basierend hierauf eine Technologieauswahl getroffen. Mit den Ergebnissen wird anhand der entwickelten Methodik der Gesamtprozess nach den technischen Kenngrosen Kohlenstoffumsatz und energetische Effizienz bewertet. Fur den Prozess ist eine energetische Effizienz von 65% und ein Kohlenstoffumsatz von 75% ermittelt worden. Die Warme- und Stoffintegration der einzelnen Prozesskomponenten bildet die Grundlage fur die energetische Optimierung. Der Einfluss verschiedener Betriebsbedingungen und Verschaltungsvarianten auf den Gesamtprozess wird mit Sensitivitatsanalysen untersucht.

toren, was zu einer deutlichen Erhohung der Cobalt-Dispersion fuhrt und somit die Aktivitat positiv beeinflusst. In einem weiteren Ansatz sollen bifunktionale, nanostrukturierte Kern-Schale-Katalysatoren hergestellt werden, um das breite Produktspektrum auf die interessanten flussigen Kraftstoffe einzugrenzen. Der aktuelle Stand der Arbeiten und die Moglichkeiten zur Kombination der Ansatze werden im Beitrag diskutiert.