Main Technologies for the Production of Anhydrous Ethanol in Brazil

Distillation is a separation technique widely used to promote the separation of components of a mixture that have different degrees of volatility. The incessant search for improvements has influenced the economic success of the processes, since distillation requires a certain energy efficiency. On the other hand, minimizing this consumption is one of the challenges. In addition, the worldwide importance of ethanol as a renewable fuel has encouraged efforts to improve production technologies. For these reasons, the three main processes for obtaining anhydrous ethanol in Brazil are discussed in this study. The azeotropic distillation despite using toxic substance and requiring high energy demand, has the lowest cost of implantation, being the most widespread and well-developed technology in the industry. In turn, extractive distillation uses low volatility and less toxic adsorbent, generating little contamination of the product with the solvent and less consumption of utilities in the process. On the other hand, the production of anhydrous ethanol by adsorption with molecular sieves uses zeolites, which allows to obtain a product free of contaminants, and can serve more demanding markets. It also has the lowest operating and utility costs, but requires the largest investment, being a robust technology with satisfactory industrial results. As a result, the choice of the process requires a detailed study of the particularities of each unit, especially taking into account the cost-benefit ratio. However, for new units producing anhydrous ethanol, there is a tendency to use selective adsorption, due to the low operating cost, high product purity, simplicity of the process and less demand for human resources.