Techno-economic feasibility of industrial production of biofuels by glycerol etherification reaction with isobutene or tert-butyl alcohol assisted by vapor-permeation membrane

Abstract

A preliminary evaluation of the techno-economic feasibility of an industrial glycerol etherification process for bio-additives production has been carried out. The attention has been focused on the etherification reaction in presence of isobutylene (IB) or tert-butanol (TBA) in a batch reactor, catalyzed by an optimized heterogeneous system. Specifically, the Hyflon-based catalyst resulted more efficient and selective to desired products than commercial resin, limiting the competitive reactions of IB oligomerization and byproduct formation. In case of IB, a mixture of poly-ethers, suitable as oxygenated additives for diesel engines, containing very low amount of mono-tert-butylethers (<2wt.%) was obtained in a single step. This allowed a simplification of the process without the need of separation units and a lower production cost with respect to other reference processes. When TBA was used and water was formed as byproduct, a permeoselective membrane was exploited improving the glycerol conversion and enhancing the poly-ethers productivity by continuous water removal. In fact, very high poly-ethers yield (>85%) was achieved under optimized reaction conditions. The analysis of the whole process demonstrated the techno-economic sustainability of the proposed routes, leading to a production price of glycerol poly-ethers of 1,14USD/kg and 2,38USD/kg, by using IB or TBA respectively.