GB827433A - Refining petroleum wax by contact filtration - Google Patents

Abstract

Petroleum waxes are refined by contacting them at 150 DEG to 450 DEG F. with a molecular sieve having a pore size of 10 to 15 . The wax may be a paraffin or microcrystalline wax and it is preferably de-oiled to an oil content of less than 1% with a solvent such as propane or M.E.K. The Specification includes a summary of the conventional methods of extracting waxes from petroleum oils and de-oiling waxes including chilling, solvent de-waxing of oils, sweating, solvent de-oiling of waxes, H2SO4 treatment or mild hydrogenation (600 DEG F., 200 p.s.i.g.) and percolation through adsorbent clay. The contacting is preferably conducted at 300 DEG to 400 DEG F. for 5 to 60 minutes using a 13 sieve. Used sieves may be regenerated by washing with solvents, e.g. hexane, secondary butyl acetate and M.E.K. mixed with toluene, but regeneration by heating at 700-800 DEG F. for 1 to 10 hours with a regenerative gas consisting of nitrogen containing less than 2 vol. per cent each of oxygen and water, less than 0.7 vol. per cent of SO2 and minor amounts of carbon dioxide is preferred. Examples of the treatment with a 13 sieve of paraffin wax extracted from a lubricating oil extract which had been de-oiled by sweating and acid treated demonstrate: (1) the relative effectiveness of (1) 5% and 20% wt. of the sieve and conventional adsorbents at 300 DEG C.; (2) 20% wt. of the sieve and conventional adsorbents at 400 DEG C.; (3) 5% wt. of fresh, solvent regenerated, and heat regenerated sieve at 300 DEG F.; and (4) 5% wt. of the sieve at 300 DEG and 400 DEG F. Preparation of the sieves.-The sieves used are zeolites which may be synthetic. A 13 sieve may be prepared by reacting a sodium silicate of high Na:Si ratio, e.g. sodium metasilicate, with a sodium aluminate having a Na:Al ratio between 1:1 and 3:1 in proportions to give a Si:Al ratio of at least 3:1, preferably between 4:1 and 10:1. The resultant precipitate is heated (as a homogeneous paste) at 180-215 DEG F. for about 200 hours, filtered, water-washed, dried and calcined at 700 DEG to 900 DEG F.