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Processes for separating waxes of different melting points from a room temperature amorphous or liquid hydrocarbon mixture in an energy conservative manner by selectively causing precipitation of crystallized waxes are disclosed. The processes involve the use of a selected co-solvent totally miscible with light and intermediate hydrocarbons from a group consisting of acetone, ketene, propanone, 2-propanone, methanol, ethanol, isopropanol, N-propanol, acetic acid, formic acid, and propionic acid or combinations thereof as a precipitating agent. Hydrocarbon mixtures, especially those with elevated pour points are first diluted by solvents such as toluene and/or methyl ethyl ketone which must be free of any significant quantity of the aforesaid co-solvents. The diluted hydrocarbon mixture at above 50° F is mixed with one or more of such selected co-solvents in a ratio preferably between 1:1 and 10:1 by weight to the heavy hydrocarbon content of the mixture; five minutes or more without artificial cooling is allowed to permit crystallization of waxes which are removed in solid form by a physical process such as filtering, settling, or the like. By controlling the amount and nature of the selected co-solvent and by including or excluding water or brine with the co-solvent, valuable waxes of high melting point may be selectively separated, or all waxes may be removed indiscriminately. Performing the separation process in several stages of adding co-solvent and/or water permits selecting out more valuable high melting point waxes first before succeeding stages reduce the wax content of the remaining liquid hydrocarbon to minimal values to enhance its value.


Chemical Engineering

Patent Number

US5196116; CA2060929 (C); NL195057 (C)

Application Filed



University of Arkansas (Little Rock, AR) Diversified Petroleum Recovery, Inc. (North Little Rock, AR)


Michael D. Ackerson, Department of Chemical Engineering

Seyed-Hamid Arabshahi, Department of Chemical Engineering

Robert E. Babcock, Department of Chemical Engineering