The liquid paraffins obtained from urea-dewaxing process generally contain aromatic hydrocarbons in the range of 3~10%.When these paraffins are used for the manufacture of detergent or plasticizer

the content of aromatics must be reduced to a permissible level. Preliminary work has shown that a fixed bed recycle adsorption process appears to be a promising technique for the removal of aromatics from the straight-run kerosine and the liquid paraffins. In order to find out the relationship between the operation conditions and the product qualities and provide basic data for pilot plant experiments

a series of tests have been carried out. In the present tests

two kinds of feed were used. One was the liquid paraffin produced from the pilot plant of saturated aqueous urea solution dewaxing (in which the paraffin-urea complex is formed in spherical clusters)

boiling range

210~260℃

content of aromatics

3~5%

and the other was the liquid paraffin produced from the polit plant of isopropyl alcohol-urea dewaxing

boiling range

210~260℃

content of aromatics

8~10%. The adsorbent was the silica gel manufactured by the Hai Yang Chemical Works

Tsingtao

China. The liquid carrier was 90~120℃ naphtha. The desorbent was technical grade benzene. The results of the texts indicate that the optimum conditions for the liquid paraffins with 3~10% aromatics are as follows. Wt. of feed/Wt. of silica gel= 2.68 -0.172 C0 (C0= aromatics in the feed

wt. %). Volume of both liquid carrier and desorbent is 70~100% of the void volume of the silica gel bed

which is equivalent to 1.0~1.5ml./gr. of silica gel. Under these conditions

when the content of aromatics of the treated liquid paraffins is less than 1%

product recovery may be held at 93~95%. The purity of the by-product aromatic concentrates is relatively high and the refractive index (nD20) can be maintained above 1.5000.