Catalytic Biorefining of Ethanol from Wine Waste to Butanol and Higher Alcohols: Modeling the Life Cycle Assessment and Process Design

Homologation of bioethanol to butanol and higher alcohols by means of Guerbet reaction was performed with a novel ruthenium based bifunctional catalyst under homogeneous conditions in the presence of a basic cocatalyst. Reaction screening demonstrated that the new catalyst shows conversions and selectivity comparable with some of ruthenium based bifunctional catalysts recently reported in the literature. The reaction occurs in pure ethanol as well as in ethanol from wine waste furnished by CAVIRO distillery with up to 46% conversion of ethanol and an overall selectivity to higher alcohols of 91% and a minor carbon loss. Based on the laboratory results, an industrialization study was carried out in order to propose a viable technological solution. The experimental data consistency was verified, and the results were up-scaled to design a reactor working in a batch or, potentially, semibatch operation mode. Further analysis of the overall process, together with the introduction of dedicated figures of merit have allowed the estimation of the process performance both in mass and energetic terms, and the outcome was integrated into a life cycle analysis. Although preliminary, the multidisciplinary approach has converged toward complementary results; more specifically, the adoption of the base cocatalyst NaOEt has showed similar performance in terms of specific alcohols production and energy demand compared to the NaOH case. Moreover, this last case proves to be better from an environmental perspective (LCA).