(314e) Study of Fusel Oil Valorization Alternatives in Bioethanol Production

Fusel oil is a byproduct of biomass fermentation in the industrial bioethanol production. It is a mixture of higher alcohols, mainly composed by isoamyl and other short-chain alcohols. Bioethanol industry is rapidly growing and fusel oil production too. Also, in countries where bioethanol is produced in large scale, byproduct utilization has become in an important issue in making the global process less polluting, more profitable and closer to the concept of biorefinery. Fusel oil has been considered as a low-value material that some ethanol producers burn to produce energy, however it can be used as a cheap and renewable source for the production of biosolvents, extractants, flavoring agents, medicinal and plasticizers. Colombian bioethanol industry produces currently around 1100 t per year of fusel oil and it is expected that this production continues growing because bioethanol is used as additive for gasoline in percentages established by local politics that stimulates the biofuels production.

Analysis and conceptual design of different alternatives to produce value-added products from fusel oil is presented. In the initial steps, experimental work in phase equilibrium and esterification kinetics of alcohols mixture found in fusel oil is made. From the experimental results, parameters for the calculation of phase equilibrium and reaction kinetics were obtained and used into the design step. A conceptual design was performed with the construction of residual curves maps (RCM), including and without including the chemical reaction effects, by means of process simulation in Aspen Plus platform. In this way, various technological alternatives are proposed for the separation of alcohols contained in fusel oil and for the production of isoamyl esters (acetate, propionate, benzoate, butyrate, among others). Finally, pilot plant facilities were constructed in order to study and validate the results of the fusel oil separation (one conventional distillation column) and reactive distillation (two reactive distillation columns) steps.