Biomass is considered to be a new and sustainable feedstock for chemicals and fuels. Biomass upgrading over zeolitic catalysts has been shown to be a viable route for the production of para-xylene. Para-xylene is currently produced in refineries from oil and is used as an anti-knock additive in fuels or is oxidized to terephtalic acid for the production of for example poly therephtalate. With the expected replacement of fossil resources with biomass in the future, biomass is seen as the new feedstock for the production of para-xylene. During biomass upgrading over zeolites, para-xylene is produced via the Diels-Alder Cycloaddition of furanic compounds and alkenes that are produced in-situ during biomass upgrading.
The Diels-Alder Cycloaddition is one of the most well studied and widely used reactions in organic chemistry. It is known that the reactivity of the substrates in this reaction is determined by their electronic structure. More specifically, the relative energy levels of the HOMO of the diene and the LUMO of the dienophile are important. Their relative difference is referred to as the HOMOdiene-LUMOdienophile energy gap. This energy gap can be related to the activation barrier: the smaller the energy gap, the lower the activation barrier and the faster the reaction.
The main goals in this research are:
Obtaining fundamental knowledge about the influences of the environment, i.e. which comes about by the properties of zeolites, on the electronic structure of reactants during the DAC reaction
- To establish the relationship between zeolite acidity and the shifts in molecular energy levels resulting in a change of the HOMOdiene-LUMOdienophile energy gap
- To clarify how the microporous structure of zeolites influences the HOMOdiene-LUMOdienophile energy gap
- To elucidate the role of the zeolite framework and active sites on the stabilization of the transition state