DEVELOPMENT OF A METHOD FOR THE ISOLATION OF HIGH-MOLECULAR-WEIGHT n-PARAFFIN HYDROCARBONS FROM SPENT “HEAVY HEXANE” IN POLYETHYLENE PRODUCTION
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Mansurov Bekhruz Akbarovich, Khayitov Ruslan Rustamjonovich
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The article presents a method for isolating high-molecular-weight normal paraffin hydrocarbons C₇-C₂₀ from spent “heavy hexane” — a technical stream generated when hexane is used as a solvent and catalyst carrier in polyethylene production. Existing separation techniques (rectification, solvent dewaxing, molecular-sieve adsorption, extraction-membrane methods, urea adduction) are compared by selectivity, energy intensity and equipment complexity, and the advantage of urea-methanol dewaxing is justified. A urea-methanol complex-formation procedure was developed and tested. GC-MS (NIST17) established a total n-paraffin content of 84.2% in the feedstock, with the target heavy fraction C₁₂-C₁₈ amounting to about 21.9%. Treatment of 248 mL of feedstock with 168 g of urea in 186 mL of methanol yielded 115 mL of n-paraffin concentrate (volumetric yield 46.4%); the urea:hydrocarbon ratio used (≈1:1) was 3-5 times below the recommended value, indicating a clear reserve for increasing extraction completeness. The prospects of using the concentrate as a natural cetane-improving diesel component are discussed.
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Authors
Mansurov Bekhruz Akbarovich, Khayitov Ruslan Rustamjonovich
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