Zinc-cobalt bimetal cyanide catalyst modified by mixed acid and preparation method thereof

Abstract

The invention provides a double-metal cyanide catalyst, a preparation method of the double-metal cyanide catalyst and a method for catalyzing polymerization reaction by the double-metal cyanide catalyst. Metal elements of the catalyst except impurities are only two metal elements, namely zinc and cobalt; the catalyst is obtained by carrying out a reaction on water-soluble metal salts of zinc and cobalt in a water-soluble solvent; the catalyst is modified by a mixed acid during synthesis, and the mixed acid comprises at least one organic acid and at least one water-soluble inorganic acid, wherein the water-soluble inorganic acid is selected from dilute sulfuric acid and diluted hydrochloric acid, and the pH value of the water-soluble inorganic acid is 0-5; the organic acid is selected fromany one or more of succinic acid, glutaric acid, phthalic acid, iminodiacetic acid, pyromellitic acid and butane tetracarboxylic acid, and the molar ratio of the water-soluble inorganic acid to the organic acid is 1:10-10:1. The catalyst provided by the invention has high activity and strong thermal stability, and can realize higher catalytic activity to polymerization reaction and higher selectivity to polymer products and polycarbonate chain links on a polymer main chain under the conditions of relatively lower catalyst concentration and higher initiator concentration.

Description

Technical field [0001] The invention relates to the field of chemistry, in particular to a zinc-cobalt double metal cyanide catalyst modified by mixed acid and a preparation method thereof. Background technique [0002] Double metal cyanide (Double metal cyanide, referred to as DMC) catalyst was first reported by General Tire Rubber Company in the 1960s. It was originally used to catalyze the ring-opening polymerization of epoxy compounds to prepare polyether polyols (such as figure 1 Shown) a type of catalyst. The polyether polyol prepared by DMC has the characteristics of low unsaturation, high molecular weight and narrow distribution, which is obviously better than the traditional KOH catalyst. Since the 1980s, DMC catalysts have gradually gained attention and applications in industry and scientific research. So far, low unsaturation, high molecular weight, narrow distribution polyether polyols prepared by DMC catalysts have become one of the main products of BASF, Bayer, Dow...

AI Technical Summary

Problems solved by technology

[0011] When industrially adopting zinc-cobalt DMC catalyst to synthesize polycarbonate polyether polyol (such as image 3 Shown) the existing problem is, in industry, when adding catalyst and the epoxy monomer mass ratio that adds will be ≤ 1 / 1000 (being 1000ppm, promptly 0.1wt%) when at least, overall production cost and the cost of catalyst residue are just Relatively low, there is economic value, otherwise, the catalyst has no application value due to the increase of production cost due to the excessive addition of catalyst

For polycarbonate polyether polyols with smaller molecular weight (number-average molecular weight 500-2000), the proportion of initiator that needs to be added is relatively high (generally 1 / 50-1 mole of epoxy monomer) / 90), under such conditions, most of the catalysts will lose their activity, or a very small number of catalysts will still maintain weak activity, but the reaction time will be greatly prolonged (more than 12 hours) to obtain the polymer, which is due to the fact that the reaction time is actually due to Higher proportion of initiator leads to deactivation of the catalyst, prolonging the activation process of the catalyst on the reactants (by hours)

It takes longer reaction time and more energy consumption, which increases the production cost

[0012] In addition, under the conditions of the above-mentioned higher ratio of initiator addition, the structural ratio of polycarbonate in the polycarbonate polyether polyol structure obtained by synthesis will be reduced (<50%), that is, the fixation of carbon dioxide rate reduction

Because the addition of a higher proportion of initiator will cause a large number of catalyst active sites to be quenched or occupied, the macroscopic manifestation is that the catalyst activity is reduced or even deactivated

The reduction of the carbon dioxide fixation rate indicates that the proportion of the low-cost carbon dioxide raw material in the polymer is reduced, which means that the proportion of the higher-cost epoxide is increased, which leads to an increase in the production cost of the polymer on the one hand, and on the other hand, is beneficial to energy saving and emission reduction. (Consumption of CO2) is also less effective

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