With increasing supply and decreasing price, from the economic point of view, it is important to utilize crude glycerol, the main by-product of biodiesel production, to produce high value-added chemicals.  The purification of crude glycerol is the first step for its utilization.  However, owing to the wide variety of triglycerides, alcohols, catalysts and separation processes used in biodiesel production, the composition of crude glycerol from different biodiesel production methods varies widely. Therefore, glycerol purification processes are also necessarily different for the various crude glycerol feed stocks. In the present work, by simple procedures, two crude glycerol samples obtained from different biodiesel production methods were experimentally upgraded to >95 wt % purity. The purification procedures were also simulated using Aspen Plus software, along with revised UNIFAC model and its parameters regressed from phase equilibrium data in literature, with good match with the experiments.  Using the same model, two other glycerol purification processes in the literature were also simulated and compared with our separation processes. We demonstrate that, as compared to alternative processes, our simple procedures work well for the purification of two crude glycerol samples investigated experimentally.  Further, this work also provides useful data and guidelines for crude glycerol purification processes, including pure component parameters, binary parameters, separation methods and separation sequences, based on different vegetable oils or animal fats as biodiesel feed stocks, different catalysts used in esterification or/and transesterification, and resulting different crude glycerol compositions.

Experimental and simulation study of crude glycerol purification from different feed stocks in biodiesel production

246th National Meeting (2013)

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