Asphaltenes removal from distillation residues

Such synthetic bitumen lends itself to a variety of modifications and uses. Steam distillation under vacuum, a universal practice in asphalt processing, would remove volatiles and the nonvolatile residue could be air-blown to asphalt. The residue from distillation, if pitch-like, could be fluted with a nonvolatile oil and excessive asphaltene constituents could be precipitated by solvent refining. 

Feedstocks. Feedstocks for the oil-fumace process are heavy fuel oils. Preferred oils have high aromaticity, are free of suspended solids, and have a minimum of asphaltenes. Suitable oils are catalytic cracker residue (once residual catalyst has been removed), ethylene cracker residues, and distilled heavy coal tar fractions. Other specifications of importance are freedom from solid materials, moderate to low sulfur, and low alkali metals. The ability to handle such oils in tanks, pumps, transfer lines, and spray nozzles is also a primary requirement. 

Asphalt A sohd residue left after distillation has removed aU other compounds from petroleum. The residue is composed of asphaltenes. 

Most coal liquids are composed of similar major chemical species, which may differ in exact composition. Liquid sulfur dioxide can be used to extract all the aromatic species of the coal liquid, free of saturated hydrocarbons and ash percursors. After removing the SO2 by degassing, distillation under reduced pressure can yield all the phenols and aromatic from the S02-solu-bles of the coal liquid. The residue, which is similar to GPC -fraction 2 of the S02 solubles, can be called coal asphaltenes. 

Refiners prepare lube base stocks from residual oils by removing asphaltenes, aromatics, and waxes. Lube base stocks are hydrofinished, blended with other distillate streams for viscosity adjustment, and compounded with additives to produce finished lubricants. 

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