Life cycle assessment of a process for paracetamol flow synthesis from bio-waste derived β-pinene

The synthesis of functional molecules from bio-waste feedstocks with retention of key structural molecular motifs is a potentially effective strategy to replace conventional fossil-based synthesis routes. In this work we are focusing on the synthesis of functional molecules from terpenes, a class of underutilised bio-waste molecules generated, for instance, as a by-product of Kraft paper pulping. Recent literature studies demonstrated a possible pathway for a continuous flow synthesis of paracetamol from β-pinene. While this process is currently not of commercial interest, the available literature synthesis demonstrates the technical feasibility of such chemical conversion as well as several new chemical transformations. However, the environmental efficiency of the proposed flow synthesis was not determined. Here, we perform a life cycle assessment to quantify the environmental impacts of a potential industrial-scale paracetamol manufacture from bio-waste β-pinene. For this purpose, scaled-up process models of continuous paracetamol manufacture were developed in Aspen Plus and a complete life cycle inventory was estimated. A GWP of 58 kg CO2-eq./kg product was predicted, and key impact contributing aspects of the designed process were identified through a hotspot analysis. A comparative feedstock analysis showed that β-pinene derived from Kraft pulping waste can be a cleaner feedstock than the benchmark feedstock benzene. The obtained LCA results represent highly conservative estimates, given the early design stage, and thus promise to surpass standard industry practises, once optimised. The results presented in this study can serve as a basis for comparison against conventional paracetamol production LCA datasets.