The use of mixtures of methyl ethyl ketone and methyl isobutyl ketone as dewaxing solvent and the dehydration of such mixtures by distillation

Abstract It has been found that anhydrous mixtures of methyl ethyl ketone with methyl isobutyl ketone can be used as very effective dewaxing solvents. Such a mixture containing 70% methyl isobutyl ketone gives a performance essentially equivalent to that obtained with the much more expensive, yet, up until now, technically preferred methyl n‐propyl ketone. For the same dewaxed oil pour point, dry mixtures of methyl ethyl ketone and methyl isobutyl ketone (and also as described previously methyl n‐propyl ketone) do not require as low filtering temperatures yet give higher filter rates than the widely employed mixtures of methyl ethyl ketone and aromatics. The continuous dehydration of mixtures of methyl ethyl ketone and methyl isobutyl ketone by distillation is also described. This operation is complicated by the fact that methyl ethyl ketone forms a binary, homogeneous azeotrope with water. The process which is described is rather unusual in that it combines some of the features of extractive distillation and also some of those of azeotropic distillation.