Preparation method of catalyst for synthesizing 1-octylene through selective oligomerization of ethylene

Abstract

The invention provides a preparation method of a catalyst for synthesizing 1-octylene through selective oligomerization of ethylene. The preparation method comprises the following steps: synthesizing a amino-containing molecular sieve; mixing the amino-containing molecular sieve, a solvent, an acid-binding agent and diphenylphosphine chloride, stirring for reaction, filtering, and recrystallizing to obtain a PNP ligand; and mixing the PNP ligand with a chromium source and a solvent, heating for reaction, filtering, washing and drying to obtain the supported heterogeneous catalyst with a structure shown in the formula (I). The synthesis of the amino-containing molecular sieve can make amino functional groups uniformly distributed on the carrier, then the PNP ligand is synthesized in situ through a reaction method of the amino-containing molecular sieve and the diphenylphosphine chloride, and the structure is more stable. The supported heterogeneous catalyst prepared by the method has the advantages that the active center of the catalyst is uniformly dispersed; and when the catalyst is applied to the ethylene selective oligomerization reaction, the catalytic activity is higher and can reach 10<6> g / (molCr.h), and the 1-octene selectivity is higher.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing a catalyst for ethylene selective oligomerization to synthesize 1-octene. Background technique [0002] 1-octene is an important organic chemical raw material, mainly used as comonomer of LLDPE, HDPE and POE, and also used as plasticizer, surfactant, lubricant, carboxylic acid, epoxy compound and rubber processing Raw materials for chemicals, etc. [0003] The non-selective oligomerization of ethylene is a traditional α-olefin production method with a wide distribution of products, among which the selectivity of 1-octene is 10% to 30%, and a separation method is required to obtain pure 1-octene. Ethylene selective oligomerization is a newly emerging technology for the production of 1-octene in recent years. The catalytic system is usually composed of ligands, chromium compounds, and cocatalysts. In 2004, Bollmann et al first reported the Cr(III)...

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Problems solved by technology

Patent CN101376113A discloses a kind of ethylene oligomerization heterogeneous catalyst supported by late transition metal on molecular sieve and its preparation method, and the catalyst system composed of it and methylaluminoxane cocatalyst is used for ethylene oligomerization reaction, but this method The active center of the prepared catalyst is unevenly distributed, especially when zeolite molecular sieve is used as the carrier. Due to the presence of aluminum hydroxyl groups and silicon-aluminum bridge hydroxyl groups, there is a certain acidity, which will lead to the polymerization of ethylene and increase the content of polyethylene wax in the by-product.

[0004] At present, most of the ethylene polymerization catalysts that have been reported are prepared by post-grafting of chemical bonds. The corresponding groups are difficult to distribute evenly on the carrier, and as the reaction proceeds, the post-grafted groups are easy to fall off.

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