Dewaxing of oils by dilution chilling - using solvent mixt. contg. methylene chloride

摘要

Dewaxing of petroleum oil stocks (esp. lubricating stocks) is carried out by passing the waxy oil through a multistage chilling zone while injecting a cold dewaxing solvent into at least some of the stages and maintaining a high agitation rate to give substantially instantaneous mixing. The pptd. wax is then sepd. from the oil-solvent mixt. and the oil is recovered from the mixt. The improvement comprises using a solvent consisting of a mixt. of (a) CH2Cl2 and (b) acetone, methylethylketone (MEK) and/or MeOH. The solvent contains >=20 (pref. 20-85) wt.% CH2Cl2. Compared with similar processes using MEK/MIBK or MEK/toluene as solvent, the process has a lower solvent requirement, gives higher dewaxed oil yields and filtration rates, and requires less energy for solvent evapn.