Method for preparing linear alpha-olefin

Abstract

The invention discloses a method for preparing linear alpha-olefin. The method comprises the following steps of: introducing catalytic solution and ethylene into a first reactor and reacting at the temperature of between 30 and 120 DEG C and under the pressure of 0.1 to 3 MPa for 1 to 40 min to prepare a first mixed material flow of first linear alpha-olefin, the ethylene and the catalytic solution; introducing the first mixed material flow and the ethylene into a second reactor and reacting at the temperature of between 40 and 90 DEG C and under the pressure of 0.5 to 4 MPa for 5 to 120 min to prepare a second mixed material flow of second linear alpha-olefin, the ethylene and the catalytic solution; performing gas-liquid separation on the second mixed material flow to obtain the ethylene and a liquid-phase product; cycling the separated ethylene to the first reactor or the second reactor for continuous reaction; and performing distillation separation on the liquid-phase product to prepare the linear alpha-olefin. The method has the advantages of mild reaction condition, simple operation and suitability for industrialized production.

Description

technical field [0001] The invention relates to the field of preparation of olefins, in particular to a method for preparing linear alpha-olefins. Background technique [0002] Linear alpha-olefins refer to C with double bonds at the ends of the molecule 4 The above linear olefins are an important petrochemical raw material. It has a wide range of applications in the preparation of high-grade detergents, high-grade alcohols, high-grade lubricating oils, surfactants and oil additives. C 4 ~C 8 The linear α-olefin is mainly used as a comonomer of linear low density polyethylene (LLDPE), which can improve the machinability, heat resistance, flexibility, transparency, etc. of polyethylene; C 6 ~C 10 C 7 ~C 11 Straight-chain alcohol is an important plasticizer intermediate, mainly used in polyvinyl chloride materials for outdoor appliances, wall coatings, automotive decorations, wire and cable materials and accessories; 11 ~C 14 The linear α-olefins are used as raw mater...

AI Technical Summary

Problems solved by technology

Both US Patent US 2004 / 0111002 and Chinese Patent No. CN 1330612C disclose the method of using this type of iron-based catalyst to carry out ethylene oligomerization in an improved plug-flow tubular reactor with a reaction temperature of 40-120°C; Compared with the continuous stirred tank reactor, the average concentration of α-olefins along the length of the reactor in the modified plug-flow reactor is much lower than that of the continuous stirred tank reactor, and the impurity content of the non-linear α-olefins formed less, which is conducive to the production of relatively pure α-olefins; compared with unimproved plug flow reactors, this method can use lower ethylene pressure, thereby reducing investment costs, but the reaction pressure in this method also needs to be maintained Above the bubble point of ethylene, it is ensured that all components (including ethylene) remain in the liquid phase, so that there is only a single liquid phase in the reactor, and the product distribution range of the resulting α-olefin is narrow

[0008] It can be seen that the existing methods for the preparation of linear α-olefins use one-step reaction or carry out a second reaction on the primary product to obtain the target product. Most of the reaction conditions are harsh, such as tending to operate at high temperature and / or high pressure, and the operation process is relatively complicated. , will increase the investment cost and operating cost of the production unit, and at the same time, the content of each component in the linear α-olefin product cannot be flexibly adjusted within a wide range

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