Simulation of an Interesterification Biodiesel Production Plant

Growing concern regarding automobile emissions and transportation energy demands has increased the viability of biodiesel production for commercial use. Biodiesel commonly consists of fatty acid methyl esters (FAME) and is typically produced from triglycerides (TG) via a transesterification reaction with methanol. However, this reaction produces glycerol as a byproduct in quantities that are quickly surpassing the market need. Alternatively, the interesterification of TG with methyl acetate (MA) produces FAME and triacetin (TA). Unlike glycerol, TA is an effective fuel additive and does not need to be separated from the FAME mixture. TA can also be sold separately from the biodiesel as a plasticizer and gelatinizing agent for polymers and explosives. Interesterification occurs in three reversible reactions that require an excess of MA, or a high methyl acetate to oil molar ratio (MAOMR), to facilitate FAME production. Typically, heterogeneous or homogenous, acid or base catalysts are used. Investigating interesterification is important considering its potential technical and economic advantages compared to transesterification. This work simulates a preliminary process model for an interesterification biodiesel production plant with a target production rate of 50,000 metric tons per year. The model was created in three stages: (1) modeling intermediate compounds in Aspen Plus; (2) obtaining and verifying published kinetic parameters using a heterogenous base catalyst; and (3) investigating separation techniques for biodiesel purification. This simulation will inform an ongoing techno-economic analysis of the biodiesel production plant.