Assessment of the environmental sustainability of solvent-less fatty acid ketonization to bio-based ketones for wax emulsion applications

The environmental and economic challenges currently faced by the wax market may be addressed by the use of sustainable bio-based alternatives. Hereto, ketonization of vegetable oils and animal fats is a potential clean reaction route towards ketone bio-waxes. In the presence of a heterogeneous TiO2 catalyst, palm fatty acid distillate (PFAD) and other commercial feedstock are selectively coupled to bio-waxes in a solvent-less liquid phase ketonization process. The resulting ketone bio-waxes show similar, if not better water repellence properties than the current benchmark paraffin waxes when tested as hydrophobization agents in aqueous wax emulsions for wood composite materials. Despite the efficient utilization of biomass carbon in accord with the prescribed Green Chemistry principles in the catalytic ketonization reaction, sustainable end products are not always guaranteed. Depending on the substrate and system scenario, the comparative life cycle assessment (LCA) shows significantly lower or higher carbon footprints in comparison to fossil paraffin. Cultivation of biomass feedstock, catalyst production and the end-of-life phase are identified as the three major hotspots in the life cycle, while the gate-to-gate impact of the proposed ketonization process design itself is rather limited. Advice is formulated to considerably improve LCA of ketone bio-waxes, achieving sustainable waxy products with appreciably lower CO2 footprints than the fossil paraffin waxes.