Patent GB-717750-A (GB)
Title: Production of lubricating oil from petroleum wax
IPC: C10M101/02
Filed: 1951-02-07
Abstract: Hydrocarbon oils of very high viscosity index, low bromine number and low Couradson carbon value are made by contacting a chlorinated petroleum wax consisting predominantly of monochlorinated wax molecules with a silica-alumina catalyst at above 550 DEG  F., but below the temperature at which appreciable cracking occurs and preferably in the range 575-725 DEG  F. for a time sufficient to remove substantially all of the chlorine from the chlorinated wax as hydrogen chloride and to produce a substantially saturated oil.  "A substantially saturated oil" is one in which the molar unsaturation does not exceed 20 per cent.  The chlorinated wax may be made by chlorination to produce a wax of less than 16 per cent chlorine content, preferably 6-12 per cent, or by adsorption fractionation of a chlorinated wax using e.g. silica gel, silica-alumina gel or alumina gel.  The wax for chlorination may be slack wax, crude scale wax or a highly refined wax.  Waxes of molecular weight above about 350 lead to higher yields of oil and are preferred to lower molecular weight waxes.  This difference in yield is illustrated in an experiment in which waxes containing about 21 and 29 carbon atoms per molecule are used.  Chlorination is usually effected at 100-250 DEG F. although if the wax is free of dissolved oxygen and the chlorination is conducted in the absence of air temperatures up to 300 DEG  F. may be used.  Dehydrochlorinatio experiments were effected with the following catalysts it being observed that the silica-alumina catalysts were markedly inferior: an acid-treated Montmorillinite clay which may be dehydrated, Florida clay, silica gel, alumina gel, activated charcoal and a diatomaceous silicon dioxide, at least 5 per cent, preferably 8-13 per cent, of catalyst should be used.  Dewaxing may be performed either immediately following chlorination or preferably immediately after dehydrochlorination.  Dehydrochlorination should be effected for sufficient time to give a product of 0 to 4 bromine number.  The oils are good lubricants at low temperatures and viscosity-temperature curves are provided.  In examples (1) crude scale wax is chlorinated to 8 per cent, a chlorinated wax fraction separated by reheating and treated with 10 per cent of either Florida clay at 500 DEG  F. for 4 hours or "Filtrol" (Registered Trade Mark) clay at 650 DEG  F. for about 2 hours, tables of characteristics of the oils thus obtained being provided; (2) illustrates the inferior nature of an oil chlorinated to 25 per cent and dehydrochlorinated at 600 DEG  F. compared with a similar oil chlorinated to 8 per cent, dehydrochlorinated at 600 DEG  F. and dewaxed, "Filtrol" clay being used in each case for dehydrochlorination; and in (3) slack wax is chlorinated to 9 per cent and treated with 15 per cent "Filtrol" clay at 640 DEG  F. for about 3 hours, dewaxed and vacuum distilled.  In a fourth illustration chlorinated wax fractions are obtained by fractional adsorption of chlorinated waxes with silica gel, treated with "Filtrol" clay at 600 DEG  F. and the products dewaxed and their characteristics noted, it being observed that the oils obtained from monochlorinated fractions are superior to those obtained from polychlorinated fractions.  Specification 694,488 is referred to.