The influence of impurities on the acid-catalyzed reaction of glycerol with acetone

The acid-catalyzed reaction of glycerol with acetone was studied in the presence of impurities that might be present in the crude glycerin of biodiesel production. These are mainly methanol, water and sodium chloride, in different amounts. The results indicated that methanol has minor effect on the glycerol conversion, whereas the concomitant addition of water and sodium chloride produces a drastic decrease of the conversion. The nature of the acid catalyst also affects the conversion in the presence of impurities. Amberlyst-15™ acid resin is more sensible to the water content than zeolite Beta. The results of the glycerol adulteration with different contaminants were compared with the reaction using a crude glycerin from a Brazilian biodiesel industrial plant.

► We studied the effect of added impurities in the reaction of glycerol with acetone.
► Water and NaCl present in the medium have the major impact on the conversion.
► Amberlyst-15™ resin is more affected by the presence of water than zeolite Beta.
► Water may facilitate the diffusion of the NaCl into the pores.