Selective catalytic conversion of biomass-derived furanic compounds: Design of solid catalysts and structure-performance relations

The depletion of nonrenewable fossil fuels and emergent environmental issues make the sustainable production of useful biofuels and chemicals from renewable biomass resources highly attractive and crucial. In line with this, the aim of this thesis was to develop efficient catalytic systems with heterogeneous catalysis to valorize biomass-derived furanic compounds into biofuels and other chemicals by acetalization, hydrogenation, reductive etherification, and aldol condensation.
Aluminum phosphates (APO-5s) and metal-modified APO-5s with suitable pore size and specific adsorption of the C=O moiety of aldehydes were developed as catalysts for furfural (FF) conversion. Weakly acidic APO-5(Al/P = 1) efficiently catalyzed FF acetalization in ethylene glycol, while more acidic APO-5(Al/P = 1.5) catalyzed catalytic transfer hydrogenation (CTH) and subsequent etherification of FF in 2-propanol (Chapter 3). Alkali earth metals (Mg, Ca, Sr, and Ba) were further introduced to tune the acidity/basicity of the acidic APO-5(Al/P = 1.5) catalyst, which additionally suppressed the subsequent etherification after CTH to improve the selectivity of CTH (Chapter 4). On the other hand, Pd nanoparticles supported on APO-5(Al/P = 1.5) selectively catalyzed reductive etherification of FF with formic acid as a hydrogen donor due to the bifunctional properties of the catalyst (Chapter 5). Moreover, the introduction of Zr into APO-5 enhanced the C=O adsorption of FF and created suitable acidic and basic sites which promoted the aldol condensation of FF with cyclohexanone (Chapter 6). Finally, KIT-6-templated mesoporous CuNiOx exhibited excellent performance in hydrogenation of FF under moderately mild reaction conditions as a result of the co-catalysis of active sites (Cu+ species and CuNi alloy phases) (Chapter 7).
Overall, the thesis work introduces new approaches to obtain heterogeneous catalyst systems with tuned reactivity for valorizing biomass-derived FF into attractive biofuel-additives and commodity chemicals of industrial interest.