Short-path distillation, also called molecular distillation, is a separation technology that has developed rapidly in recent years. It can solve the separation problems of substances with heat sensitivity and high boiling point. It is called distillation, but the principle is different. Ordinary distillation relies on the difference in boiling point, while molecular distillation relies on the molecular mean free path. What is free course? It is the straight-line distance between a molecule and another molecule in two successive collisions (a rough understanding means how far the molecule can travel by thermal motion). The mean free path is a statistically average result.
Molecular distillation is used in the fields of petrochemicals, food, medicine, flavors and fragrances and fine chemicals, especially in the separation and purification of heat-sensitive materials. For example, the extraction of refined fish oil. The EPA and DHA in fish oil (this thing is called brain gold, and many infant products contain this ingredient) are mainly extracted from marine fish oil. The molecularly distilled fish oil product has good color and low peroxide value. . In addition, the extraction of pigments, vitamins, and volatile essential oils all use molecular distillation. In the petrochemical industry, it can be used for the refining treatment of synthetic lubricating oil base oil, as well as for oil analysis, and is used in the deep drawing field of vacuum distillate. In the field of medicine, it is used for the purification of drugs or intermediates (for example, the purification of methyl 4-methoxyacetoacetate, the key intermediate of anti-HIV-1 drug dulutvir).
The combination of molecular distillation technology and other advanced technologies can solve more practical problems. However, the mechanism research on the internal fluid mechanics and mass transfer and heat transfer process of molecular distillation apparatus is not comprehensive enough. Further research should be conducted to establish corresponding mathematical models to provide theoretical basis for molecular distillation technology to solve practical problems. At the same time, we should vigorously develop low-cost, high-throughput molecular distillation equipment, so that molecular distillation technology can achieve large-scale industrial applications.
