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Biodiesel is a sustainable and renewable fuel generated from renewable resources, including vegetable oil or animal fats. It is thought to be a non-toxic fuel that degrades gradually and causes no harm to the environment. In the present study, a non-conventional supercritical method for industrial biodiesel production is investigated. The non-conventional method refers to a single-step interesterification reaction between triglycerides and methyl acetate resulting in methyl esters of fatty acids and triacetin as a secondary product. Process flowsheet modeling, using CHEMCAD chemical engineering software, was used as an investigation tool. The production capacity was set to 25,000 kg/h biodiesel. Methyl acetate requested in the biodiesel production is produced from methanol esterification with acetic acid using an intensified reactive distillation unit. Methanol, in turn, is obtained using synthetic gas derived from biomass as a raw material, the process representing a new method at the industrial level to solve problems related to the energy that is required, storage and disposal of residual materials, and pollution through the release of pollutants into the air. The methanol synthesis process is similar to the one based on natural gas, consisting of three main steps, namely: (i) synthesis gas production, followed by (ii) methanol production, and (iii) methanol purification. Acetic acid is an essential chemical product, generated in the proposed approach by a sustainable method with low energy consumption and low air emissions, more exactly methanol carbonylation. All the processes previously mentioned: (i) biodiesel production, (ii) methyl acetate production, (iii) acetic acid production, and (iv) methanol production were modeled and simulated, leading to the desired biodiesel productivity (e.g., 25,000 kg/h) with the obtained purity being higher than 99%. Relevant discussions regarding the design assumptions used, the simulation and validation results, as well as other technical issues (i.e., electricity and thermal energy consumption) for the system being simulated, are provided, leading to the conclusion that the proposed route is well suited for the desired application and can deliver significant results. The simulation outcomes have provided confidence in the feasibility and effectiveness of the chosen process design, making it a viable option for further development and implementation.
Petrescu et al. (Sun,) studied this question.