Multiscale Modeling Approach to Biomass Valorization: Solvent Effects
With the depletion of conventional fossil fuels not only the need for alternative energy sources increases, but also the need for alternative ways to make platform chemicals rises. Biomass valorization, therefore, is of growing importance. It encompasses a wide range of aqueous reactions. One example is the conversion of cellulose to platform chemicals: First cellulose can be hydrolyzed to D-glucose, and then transformed to a large range of platform chemicals (see Figure 1). Water, however, is not – like most solvents – an inert spectator, but its unique ability to form hydrogen bonds ensures that water plays an active role in the chemistry of its solutes .
The key objective of my research is the elucidation of the effect of water (and other solvents) on the mechanisms of important reaction steps involved in the conversion of D-glucose to platform chemicals. In order to explicitly incorporate solvent molecules in my calculations I use a multiscale modeling approach. In this study the multiscale method of choice are adaptive QM/MM methods [2,3,4]. While standard QM/MM methods assume a fixed definition of the QM and MM region, the adaptive QM/MM schemes allow for diffusion of solvent molecules by re-assigning atoms to the QM or MM region every single time-step. These adaptive QM/MM techniques are coupled to metadynamics and other rare-events techniques in order to map free energy profiles for the reactions
Figure 1: Biomass conversion processes for which computational studies of solvent and catalytic effects are of value. The processes range from the conversion of small molecules (blue and green) towards those involving complex networks of polymers (yellow). This study is focused on the processes in the blue field.
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