Process Analysis of Biodiesel Production – Kinetic Modeling, Simulation, and Process Design

Techno-Economic Analysis of Interesterification for Biodiesel Production

“…Following the simulation work of Casas et al, 61 the UNIQUAC thermodynamic model was chosen for all units except those processing pure water, which used steam tables. According to Margarida et al, 22 the most important parameters to verify for components that are not readily available in the Aspen Plus database are the molecular weight (MW), critical temperature (T C ), critical pressure (P C ), normal boiling point (T B ), and acentric factor (ω). For FAME and triolein, the values of T C , P C , T B , and ω are sourced from Peŕez-Cisneros et al 62 For the intermediates DAMG and MADG, the MW and structure of the molecules were entered into Aspen Plus and used to estimate the UNIFAC r and q parameters with the Bondi method.…”

“…20−22 Typically, alkaline-catalyzed transesterification reactions are faster than acid-catalyzed ones, with acid catalysts requiring reaction times on the order of hours, compared to minutes in the case of alkaline catalysts, for comparable conversions. 20,22,23 However, alkaline catalysts are sensitive to water and free fatty acid contaminants common in waste oil which can poison the catalyst and promote saponification. 20,22 Therefore, the TG feed to a reactor loaded with an alkaline catalyst must be purified, contributing to elevated feedstock costs in alkaline-catalyzed biodiesel plants.…”

“…20,22,23 However, alkaline catalysts are sensitive to water and free fatty acid contaminants common in waste oil which can poison the catalyst and promote saponification. 20,22 Therefore, the TG feed to a reactor loaded with an alkaline catalyst must be purified, contributing to elevated feedstock costs in alkaline-catalyzed biodiesel plants.…”

“…Interesterification can be catalyzed with homogeneous or heterogeneous catalysts or conducted non-catalytically under supercritical conditions. Non-catalytic interesterification has been explored by several authors, , but the relatively high temperatures required can lead to undesirable effects, such as thermal degradation of the biodiesel. , Homogeneous catalysts provide relatively fast reaction rates; however, compared to heterogeneous catalysts, homogeneous catalysts require costly and energy-intensive downstream separations to remove the dissolved catalyst and tend to be more difficult to reuse. − Typically, alkaline-catalyzed transesterification reactions are faster than acid-catalyzed ones, with acid catalysts requiring reaction times on the order of hours, compared to minutes in the case of alkaline catalysts, for comparable conversions. ,, However, alkaline catalysts are sensitive to water and free fatty acid contaminants common in waste oil which can poison the catalyst and promote saponification. , Therefore, the TG feed to a reactor loaded with an alkaline catalyst must be purified, contributing to elevated feedstock costs in alkaline-catalyzed biodiesel plants.…”