Biomass is a renewable feedstock which holds great potential to satisfy our future need for fuels and chemicals. Noble metal based catalysts have been investigated extensively, also for biomass based conversions because of their activity and stability. However, their availability is limited so there is a need for developing non-noble metal based catalysts such as Ni or Cu.
Highlight of the past year
Last year we studied the hydrothermal conversion of C6 polyols (sorbitol) and sugars (glucose) with a Ni/AC catalyst (Fig. 1) in alkaline anaerobic conditions. It has been shown before that under these conditions Ni is stable. We investigated the role of the base comparing KOH and Ca(OH)2.
Lactic acid was the main reaction product obtained in the liquid phase at 150ºC in inert atmosphere for the two feedstocks when using KOH as a base. However, a wide range of other oxygenated products was also obtained to a lesser extent (such as glyceric acid, glycolic acid, formic acid or ethylene glycol).
The type of base played a key role on the selectivity (Fig.2). Ca(OH)2 resulted in a higher LA yield compared to KOH. The presence of divalent cations enhances the selective formation of lactic acid during alkaline hydrolysis and decreases the total amount of other reaction products, because it affects the position where the C-C cleavage of the feed molecule (preferentially C3-C4 scission) occurs.
Type of student projects envisioned
Some sub-projects for bachelor and master students are available at the moment. The projects are highly experimental, i.e. catalyst synthesis, characterization and testing. Therefore students need good lab skills. In addition there is one project available in which modelling (process design and sustainability analysis) plays a more important role.