Discovering tomorrow

InnoVenton and The Downstream Chemicals Technology Station

"The direct hydrothermal liquefaction of micro algae in a continuous flow tubular reactor"

There has been considerable recent research activity investigating the utilization of micro algae to capture CO2 and the conversion of microalgal biomass to renewable liquid fuels by thermochemical methods. The conversion of microalgal biomass to liquid fuel material by direct hydrothermal liquefaction has an advantage in that the conversion may be carried out in water and thus eliminates the need to dry the microalgae feedstock. Despite this advantage and recent research efforts, few hydrothermal techniques have progressed beyond bench scale. The direct hydrothermal liquefaction of microalgal biomass under subcritical conditions provides a liquid water reaction medium with unusual properties and allows it to act as solvent, reactant and catalyst to produce crude bio oil. Previous researchers found that the isolated crude bio oils obtained from batch liquefaction studies typically have energy values of 30-40 MJ/kg and are composed mostly of higher molecular weight hydrocarbons and fatty acids.

In order to develop a method for the preparation of larger quantities of crude bio oil for further study and to evaluate if there is any significant difference in the composition of the isolated crude bio oil compared to that reported for small batch reactor systems, we have investigated the direct hydrothermal liquefaction of micro algae using a continuous flow tubular reactor. Results obtained with a 24m (3/8”o.d.) continuous flow tubular reactor show that the crude bio oil obtained had significantly lower energy value (17 MJ/Kg) and higher content of lower boiling point oxygenate compounds.

"Vapour phase dehydrogenation of cyclohexane under oxygen deficient conditions on microstructured reactors"

The study involved the oxidative dehydrogenation of cyclohexane in a microstructured reactor containing a wall coated iron-modified vanadium phosphate catalyst.

The study was approached by, first studying the properties and performance of various iron-modified vanadium phosphate catalyst for the oxidative dehydrogenation of cyclohexane. In so doing firm scientific basis for the interpretation of the performance of the wall coated catalysts was established. The catalyst study involved the use of advanced analytical techniques such as powder X-ray diffraction and others to characterize the behavior of the phosphate catalyst during short and long term reactions. A micro-structured reactor containing reaction channels of a few micrometers was coated with the desire catalyst and the said catalytic reactor was tested against a tubular fixed bed reactor for the oxidative dehydrogenation of cyclohexane. On running the dehydrogenation reaction under oxygen deficient conditions, it was for the first time established that the iron modified catalyst can seamlessly switch from oxidative dehydrogenation to normal dehydrogenation. On testing the two reactors cyclohexane conversion was more than twice to the one obtained on the fixed bed (20%) despite using five times less catalyst. The outcome clearly demonstrates the advantage of reaction intensification micro-structured reaction technology can provide.

 

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