Novel Two-Stage Process for Manufacturing Butadiene from Ethanol
2021
Dimian, Alexandre C. | Bezedea, Nicoleta Ilona | Bildea, Costin Sorin
Replacing petrochemicals with products obtained from renewable raw materials is a top challenge today. The paper deals with the design and simulation of a sustainable process for manufacturing butadiene from bioethanol with a capacity of 91,000 t/year. The two-stage process employs a selective CuO/Cr₂O₃ catalyst for ethanol dehydrogenation and recent yield-performant Ta₂O₅ catalyst for butadiene synthesis. The paper develops original flowsheets suitable for industrial implementation based on comprehensive kinetic models that provide a realistic description of the actual chemistry. The development of a complex separation system makes use of a systematic task-oriented methodology. Efficient separation methods are applied according to the chemical nature and physical properties of species for removing numerous impurities generated in reactions. The overall butadiene mass yield and carbon yield are 0.495 kg butadiene/kg ethanol (vs the maximum value 0.587) and 0.837, respectively. The catalyst productivity is 0.253 kg butadiene/kg cat·h. Substantial energy savings are achieved by heat recovery around the chemical reactors and by applying heat pumping for ethanol recovery and recycling. The sustainability analysis reveals low material intensity (0.227 kg waste/kg butadiene), moderate energy intensity (0.562 kW h/kg electrical energy and 15.8 MJ/kg thermal utilities), and low impact on the environment. The economic analysis pinpoints the possibility of achieving butadiene prices competitive with petrochemical products if the process is integrated in a biorefinery.
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