Obtenção da configuração otima do processo de destilação extrativa do etanol utilizando os solventes glicerol e dipropilenoglicol

Abstract

Given the growing concerns about environmental issues and the continuous search for new sources of renewable energy, anhydrous ethanol plays a prominent role in sustainable development and in addressing energy challenges linked to the dependence on fossil fuels. Considered a symbol of innovation, anhydrous ethanol is produced through physicochemical and biological processes, with particular emphasis on the unit operations used in the separation of water and alcohol. One of the main challenges in separation processes, especially distillation, arises from the fact that the alcohol-water mixture forms an azeotrope, making it difficult to separate the two compounds. In this context, extractive distillation emerges as a viable alternative to overcome this challenge, enabling the production of anhydrous ethanol with higher purity and efficiency. Given this issue, the present study aims to optimize the extractive distillation process of ethanol using glycerol and dipropylene glycol as solvents, with the goal of improving energy efficiency and obtaining a product that meets the minimum technical specification of 99.3 %w ethanol required by the National Agency of Petroleum, Natural Gas, and Biofuels. To achieve this, a computational simulation was carried out using the free software DWSIM and the NRTL thermodynamic model, where variables such as the number of theoretical stages, reflux ratio, solvent composition, and operating pressure were analyzed. The results indicated that the configuration with the best separation efficiency was an extractive distillation column with 22 stages, with the ethanol feed introduced at the twelfth stage and the solvent entering at the fourth stage. Additionally, the best results were obtained by adding a solvent mixture composed of 70% glycerol and 30% dipropylene glycol. Under these operating conditions, it was possible to obtain anhydrous ethanol with an alcohol content of 99.31 %w and reduce energy consumption by 17.84%, demonstrating the effectiveness and feasibility of the process. Therefore, the efficacy of extractive distillation using glycerol and dipropylene glycol as a promising and sustainable alternative for ethanol purification is evident, providing not only higher ethanol purity but also a significant reduction in environmental impact and operational costs, contributing to the economic and environmental viability of the process.