Method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on basis of polyether pyridinium ionic liquid

Abstract

The invention relates to a method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on the basis of a polyether pyridinium ionic liquid. According to the method, a two-phase catalytic system is adopted, the catalytic system comprises a polyether pyridinium ionic liquid PPYILs with room temperature liquid-solid phase change characteristics, a rhodium catalyst, diphosphine ligands, a reaction substrate olefin and a reaction product aldehyde, a liquid / liquid two-phase hydroformylation reaction is performed at certain reaction temperature and under certain synthesis gas pressure, and the rhodium catalyst is recovered and cycled through simple two-phase separation after the reaction ends. The catalytic system has high catalytic activity, high selectivity, ultralong service life and very low rhodium catalyst loss amount, wherein the TOF value reaches 160-220 h<-1>; the area selectivity of normal aldehyde reaches 96%-98%; the catalytic cycle accumulated TON value is approximately 40,000; the rhodium catalyst loss amount is only 0.06%-0.2%.

Description

technical field [0001] The invention relates to the technical field of chemistry and chemical engineering, in particular to a method for preparing normal aldehyde with high selectivity by two-phase hydroformylation of olefins based on polyether pyridinium salt ionic liquid. Background technique [0002] The rhodium-catalyzed hydroformylation of olefins is a typical atom-economical reaction, and it is also a carbonylation reaction with more reports in the literature. It has become an ideal method for the preparation of high-carbon aldehydes / alcohols. Homogeneous hydroformylation has the advantages of high catalytic activity, good selectivity and mild reaction conditions, but the separation and recycling of rhodium catalysts has been the focus of attention in the field of homogeneous catalysis for a long time. [0003] In recent years, the liquid / liquid two-phase catalytic system with ionic liquid as the catalyst carrier has developed very rapidly, and has become one of the mo...

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Problems solved by technology

Homogeneous hydroformylation has the advantages of high catalytic activity, good selectivity and mild reaction conditions, but for a long time, the separation and recycling of rhodium catalysts has been the focus of attention in the field of homogeneous catalysis

[0004] However, an outstanding problem faced by the ionic liquid two-phase catalytic system is: how to effectively dissolve and load the rhodium-phosphine ligand complex catalyst in the ionic liquid, and effectively prolong the life of the rhodium catalyst while maintaining high catalytic activity and high selectivity. service life

[0006] Although the above studies have solved the immobilization problem of rhodium catalysts in ionic liquids to a certain extent, and can maintain higher catalytic activity and selectivity in a certain number of cycles (up to 10-15 times), so far, Among all the ionic liquid catalytic systems reported in the literature, there is no system that can simultaneously have high catalytic activity, high selectivity (including chemoselectivity and regioselectivity) and long service life. The main reasons are: first, a large number of ions The application of liquid increases the mass transfer resistance of substrate molecules, and the negative effects of ionic liquids (caused by various complex factors such as high viscosity and residual impurities) become more significant, resulting in a serious decline in catalytic activity and selectivity; Rhodium catalysts in ionic liquids may undergo oxidation, decomposition, clustering, or loss behavior, resulting in reduced stability and lifetime

[0007] Recently, based on a class of polyether alkylguanidine salt ionic liquids (ZL201210064537.5) with room temperature liquid-solid phase transition properties, we constructed a two-phase hydroformylation system for olefins. Due to this new type of functionalized ionic liquid It can effectively immobilize the Rh-TPPTS catalyst, and has a remarkable ability to stabilize the rhodium catalyst. The rhodium catalyst can be recycled up to 35 times, and the catalytic activity and selectivity remain unchanged. The cumulative TON value reaches 31188. However, this two-phase catalytic system The catalytic activity is low, and the TOF value is only 10-200h -1 , especially, from 1-octene to 1-tetradecene, with the increase of the carbon chain, the reaction rate drops sharply, and mass transfer becomes the key factor that inhibits the improvement of catalytic activity; in addition, the most prominent problem is that the system is The regioselectivity of aldehydes is poor, and the anisotropic ratio is only 2.0:1-2.4:1 (67-71% regioselectivity of aldehydes), and aldehydes have important applications in many fields

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