SU1734816A1 - Method of preparing rhodium-containing catalyst - Google Patents

Abstract

The invention relates to catalytic chemistry, in particular the preparation of a rhodium-containing catalyst, which can be used in hydrogenation, hydroformylation and isomerization processes. The goal is to simplify the way. The process is carried out by treating polyvinyl chloride or a haloid-containing polystyrene with a phosphating agent, an alkali metal diphenyl phosphide, used as lithium diphenylphosphide prepared from triphenylphosphine, followed by decomposition of the resulting phenyl lithium with tertiary chloride, and fixing it with the help of the partition to get the help, and you can use the item to get the help, and you can use the body to apply the key, and you can use the partition to create a polymethylocente solution using a polyvinyl chloride solution. give birth to carbonyls. In this case, the number of stages of preparation of the JV with

Description

The invention relates to the field of petrochemical synthesis, more specifically to a method for producing homogeneous rhodium catalysts. Rhodium phosphine complexes are used as effective catalysts for the hydrogenation, hydroformylation and isomerization of olefins.

The most known and widely used in industry for the catalysis of these reactions are cobalt carbonyls, cobalt and rhodium phosphine complexes. The latter have the highest activity in the indicated reactions.

However, in processes involving the use of high molecular weight olefins (C and above) as the feedstock, considerable difficulties arise with the separation of the catalytic complex from the reaction products.

This problem can be solved by fixing transition metal complexes on the surface of solid inorganic or organic carriers. However, in this case, such advantages of homogeneous catalysis as high catalyst activity are lost. In addition, heat removal is difficult in heterogeneous catalysis, which can lead to catalyst destruction.

The use of soluble polymeric phosphines as ligands of the rhodium complex has been found to produce a catalyst that is easily separated from the reaction products due to differences in molecular weights.

Closest to the invention is a method for the preparation of a polymer soluble catalyst, which consists in using rhodium VI as ligands.

WITH

00

about

complex of modified polytyrene or polyvinyl chloride.

Original polystyrene to obtain igandan is subjected to chloromethylation.

{CH -Sn}; -LaSMASN.SSCH / - O-L-CH t-CHiOH

I j / h

(0)

C-NlSS. ft)

Then phosphinate using potassium diphenyl phosphide as the phosphinating agent, obtained by the reaction

RRpz + 2K -KPPh2 + PhK

in dioxane for 7 hours at boiling. The resulting solution is treated with a chloromethylated polymer (1) dissolved in dioxane (the polymer contains 3.3% chlorine). By using stoichiometric amounts of potassium diphenyl phosphide, a polymer is obtained containing 2.59% chlorine and 0.45% phosphorus. Complete replacement of chlorine is achieved by using an excess of potassium diphenyl phosphide.

In the case of polyvinyl chloride, the starting polymer is also treated with a mixture of potassium diphenylphosphide and phenyl potassium.

  CRF -

4sn-sn) {sn4-sn} ъ

Ppb

The resulting polystyrene or polyvinyl chloride ligands are purified by precipitation in methanol and drying.

HRh (CO) (PPP) h - rhodium phosphine complex or acetylacetonate complex Rh (CO) a (acac) is used as the source of rhodium for the preparation of the catalyst.

For the application of rhodium onto the polymer, the carrier is dissolved in dioxane or benzene and HRh (CO) (PPhH3) 3 or Rh (CO) 2 (acac) is added to the resulting solution in an inert atmosphere. The mixture is kept at room temperature for 17-25 hours in an inert atmosphere, after which the catalyst is purified by repeated reprecipitation from benzene (dioxane) to methanol or by membrane filtration.

The resulting catalysts are active in the reactions of hydroformylation of hexene-1 at 100 ° C and 10 MPa (CO / H2 1/1). In 17 hours, using a complex based on polystyrene and Rh (CO) 2 (acac) hexene-1, it is quantitatively converted into a mixture of heptanals. Under the same conditions, using a complex based on polyvinyl chloride, 90% conversion of hexene-1 is achieved, and up to 60% n-heptanal is formed. The products are separated from the catalyst by membrane filtration.

A disadvantage of the known method of polymer catalyst is its multistep, use in the synthesis of hard-to-reach chloromethyl ether, explosive metallic potassium. The aim of the invention is to simplify the method.

This is achieved by a method of preparing a rhodium-containing catalyst, comprising processing of polyvinyl chloride or a halide-containing catalyst.

0 polystyrene phosphinating agent, which is used as lithium diphenylphosphide, obtained from triphenylphosphine, followed by decomposition of the resulting phenyl lithium tertiary

5 chloride butyl, and fixing rhodi on the polymer directly in the reaction of carbonyl rhodium.

Example 1. Preparation of a ligand for a rhodium catalyst based on polystyrene.

A 250 ml 3-necked flask, pre-purged with argon, equipped with an effective stirrer and cooler, is loaded with a solution

5 diphenylphosphide lithium in tetrahydrofuran, obtained in a known manner from 7.5 g of triphenylphosphine, 0.41 g of metallic lithium and 2.6 g of tertiary butyl chloride. After that from the dropping funnel

0 serves a solution of brominated polystyrene (4.1 g) in 30 ml of tetrahydrofuran. Bromine content in polystyrene 15.7%. The mixture is kept at 20–25 ° C and stirred for 12–15 h. Unreacted organic lithium is decomposed with distilled water (50 ml), after which the reaction mass is placed in a separatory funnel where the aqueous layer is separated; the polymer from the organic layer is precipitated by

0 addition of 2 times the amount of hexane. The selected polymer is dried under vacuum (1-2 mm. Hg. Art.) At 70-80 ° C for 5 hours. The resulting product (4.0 g) contains 4.4% phosphorus and 2.8% bromine.

5 EXAMPLE 2. Preparation of a ligand for a polyvinyl chloride based rhodium catalyst.

In a 250 ml flask with a capacity of 250 ml, purged with argon., Put a solution of polyvinyl chloride (4 g) in 50 ml of tetrahydrofuran and

process the polymer with a solution of diphenylphosphide lithium in tetrahydrofuran, prepared from 1.98 g lithium, 37.8 gtriphenylphosphine and 7 g tertiary butyl chloride. The mixture was kept under stirring at a temperature of 20-25 ° C for 12 hours, after which the polymer was isolated and dried, as in Example 1. The resulting product contains 10.6% phosphorus and 2.5% chlorine. The degree of substitution of chlorine for phosphine groups is 56%; on phenyl groups - 30%.

Example 3 (comparative). Preparation of phosphated polyvinyl chloride without decomposition of phenyllithium.

To 125 ml of tetrahydrofuran, in which 10 g of polyvinyl chloride (MM 150,000) is dissolved, slowly, with stirring and cooling (15-20 ° C) under argon atmosphere, 80 ml of a solution of lithium diphenylphosphide and phenyl lithium in tetrahydrofuran are added.

This solution is obtained by reacting 42 g of triphenylphosphine and 2.21 g of lithium metal, as in Example 1, after the reaction, the addition of tertiary butyl chloride is not produced. The polymer is isolated in the usual way. The resulting product contains 8.7% phosphorus and 1.08% chlorine. The degree of substitution of chlorine for phosphine groups is 41%; on phenyl groups of 54%.

Example 4. Hydroformylation of dodecene-1 on a rhodium catalyst fixed on phosphinated polystyrene soluble in the reaction medium.

A 350 cm3 autoclave is charged with a solution of 1.37 g of phosphated polystyrene containing 4.4% phosphorus and 2.8% bromine in 30 ml of benzene, and also a solution of Rh4 (CO) i2 (0.047 g) in 95 ml of benzene, after which 25 ml (19.0 g) dodecene-1 is added to the mixture. The autoclave is flushed with carbon monoxide and in it carbon monoxide creates a pressure of 0.2 MPa, after which it is heated to 90 ° C. Upon reaching the working temperature, the pressure of carbon monoxide is adjusted to 0.5 MPa and hydrogen is fed into the reaction mixture, bringing it to the working (1.00 MPa).

The progress of the reaction is judged by the pressure drop in the graduated buffer, from which synthesis gas (CO / H2 1/1) is fed into the autoclave as the reaction proceeds.

Chromatographically determined that in 120 minutes, the conversion of the olefin is 91%. 68.1% tride-feed was detected in the products; 20.8% 2-methyldodecanal} and 2.1% dodecane (on the initial olefin). The catalyst is separated from the reaction products using an average cellulose acetyl membrane membrane.

pore diameter of 250 A, treated for 3 hours 0.02 n. NaOH solution. The analysis of the filtrate shows the absence of rodi compounds. A decrease in the catalytic activity of the system over 5 cycles of operation is not observed.

The dodecene-1 is hydrogenated with the catalyst obtained. The hydrogen pressure is 2.0 MPa, the temperature is 90 ° C. Converse

olefin for 6 hours is 62.5%.

Example 5. Hydroformylation of 1-hexene on a rhodium catalyst fixed on the phosphinated solution dissolved in the reaction medium.

polyvinyl chloride.

A solution of phosphated polyvinyl chloride (1.99 g) containing 10.6% of phosphorus and 2.5% of chlorine in 30 ml of benzene and a solution of 0.235 g of Rh4 (CO) i2 in

95 ml of benzene, as well as 25 ml (16.8 g) of hexene-1. The reaction conditions are the same as in Example 4. For 8 hours, the conversion of the olefin is 89%. In the reaction products found 52.4% 2-methylhexenal and 35.6%

heptanal, as well as 0.9% hexane (on the initial slafin).

The data presented in the examples confirm that the method of phosphating polystyrene with lithium diphenyl phosphide, obtained from triphenylphosphine and metallic lithium, followed by decomposition of the resulting phenyl lithium with tertiary outil chloride, improves the selectivity of the phosphine reaction.

The absence of rhodium compounds in the reaction products that passed through the membrane confirms the possibility of obtaining a catalyst directly in the reaction medium from Rh4 (CO) i2 and a phosphated polymer,

which reduces the number of stages for the preparation of a soluble rhodium catalyst fixed to the polymer.

Claims (1)

The method of preparing a rhodium-containing catalyst, comprising treating polyvinyl chloride or halo-containing polystyrene with an alkali metal diphenylphosphide phosphine agent and attaching a rhodium to a polymer from a rhodium compound, characterized in that, in order to simplify the method, a crystal is used as a phosphorus agent from a rhodium compound, characterized in that it is used to put a ray on the phosphorus agent. lithium obtained from triphenylphosphine, followed by decomposition of the resulting phenyl lithium with tertiary butyl chloride, and fixing the rhodium on the polymer is carried out directly in the reaction of carbonyl rhodium. X