Butadiene from biomass, a life cycle perspective to address sustainability in the chemical industry

In the past few decades, innovative approaches such as Green Chemistry and Green Engineering have come out in order to set the basic principles for a more sustainable chemical industry. However, researchers also need a more scientific and quantitative tool to address the sustainability behind the application of those principles. Therefore, a multi-criteria approach based on life cycle thinking was proposed to investigate the production of 1,3-butadiene. Five indicators were selected to address sustainability: the Cumulative Energy Demand, the carbon footprint, the water depletion, a midpoint-oriented analysis method and an economic index. The use of renewable feedstock was evaluated in comparison with the traditional fossil-based route from naphtha. Two alternative pathways which use bio-ethanol were considered - the Lebedev and Ostromisslensky processes - evaluating the possibility to locate the plant in three different regions (the EU, Brazil and the US). Detailed analysis reveals how the use of bio-based feedstock leads to a significantly lower consumption of fossil sources, despite the higher exploitation of renewable resources leading to larger water withdrawals. Moreover, the assessment of the global warming potential reveals how bio-routes are far from able to be considered carbon-neutral. In addition, the ReCiPe single-score was used, showing greater sustainability of the Lebedev process compared with the traditional way. On the other hand, the two-step pathways (Ostromisslensky) result in the worst scores. An economic evaluation was also applied. The index reveals how the direct conversion into 1,3-butadiene seems more suitable than the two-step method, particularly in the case of production in the US.