Method for producing elemental N-alkanes

Abstract

The invention relates to the field of chemical engineering, and discloses a method for producing elemental N-alkanes. The method comprises the following steps of a pretreatment step, namely sequentially putting raw materials into a main fractionation tower and a stabilizer, and carrying out distillation under the effects of certain pressure and temperature to obtain stable distillate; and a distillation step, namely putting the stable distillate into fractionation towers, carrying out fractionation under the effects of certain pressure and temperature to obtain elemental N-alkanes, wherein the number of the fractionation towers is 2N-1; the variety number of the obtained elemental N-alkanes is N; and N is an integer of 1-6. The production technology of the elemental N-alkanes is simple and feasible, a product is convenient and fast to separate, the equipment investment is reduced and the energy consumption is reduced.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for producing elemental normal alkanes. Background technique [0002] The main method for the production of existing C5-C10 elemental normal alkanes is: using naphtha as raw material, separating normal alkanes and non-normal alkanes in naphtha through molecular sieve adsorption, using 5A molecular sieve as adsorbent, and using low-level normal alkanes Paraffins, ammonia, hydrogen or water vapor are used as desorbents, and the selective adsorption performance of 5A molecular sieves is used to separate normal paraffins in naphtha in industry to obtain high-purity normal paraffins. Elemental n-paraffins are obtained by rectification. [0003] In this production process, the existing pressure swing adsorption extraction process for high-purity n-hexane products adopts a four-tower heating and pressure swing adsorption process to realize the desorption of the adsorbent n-hex...

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Problems solved by technology

[0005] The existing technology generally uses petroleum products as raw materials. The composition of petroleum is complex, containing aromatics, cycloalkanes, S, N, O, etc., and the characteristics of molecular sieves. The production of simple n-alkanes requires that the raw materials do not contain sulfur. The pretreatment process is complicated, the process is long, and the investment is large

In addition, the desorbent commonly used in the production process is a small molecule gas, which requires a low subsequent condensation temperature, even below zero, a high condensation pressure, large energy consumption and equipment investment. Additional problems such as regeneration difficulties

Furthermore, the composition of petroleum distillate raw materials is complex, and the boiling points of different components overlap more, and the boiling points of normal and non-normal components are similar (such as the boiling point of n-hexane is 68.7°C, and the boiling point of methylcyclopentane is 71.8°C, the difference between the two is only 3.1°C), and the content of isomeric components is high, it is difficult to separate by rectification, and the energy consumption is high, so it is impossible to produce a series of simple n-paraffins by simpler methods

It is necessary to separate normal paraffins from other non-normal hydrocarbons first, and then use rectification to obtain high-purity simple normal paraffins. The process is complicated

At the same time, in the first step of separating normal alkanes and other non-normal hydrocarbons, a large amount of energy is consumed in the process of adsorption and desorption, which reduces the economical efficiency of the entire device.

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