Separation method of n-heptane

Abstract

The invention belongs to the field of chemical medicament manufacturing, and relates to a separation method of n-heptane, which comprises the following steps: carrying out counter-current extractive distillation on straight-run naphtha and an extraction agent in an extractive distillation tower, and condensing a gas phase at the top of the extractive distillation tower to obtain an intermediate product rich in n-heptane; the intermediate product is cooled and then sequentially enters a two-stage vacuum rectification system to be subjected to two-stage vacuum rectification purification, and an n-heptane crude product is obtained; the n-heptane crude product passes through a fixed bed adsorber filled with a modified molecular sieve, residual sulfide and olefin substances in the n-heptane crude product are removed, and an n-heptane product is obtained; the modified molecular sieve is obtained by sequentially carrying out aluminum nitrate impregnation, silica sol loading and disodium hydrogen phosphate modification treatment on a molecular sieve. The method provided by the invention comprises extractive distillation, two-stage vacuum distillation and molecular sieve adsorption refining, each stage plays a role in separating specific impurities, and the purity and process economy of the n-heptane product are remarkably improved.

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