CN1978055B - Hydroformylation catalytic system and use - Google Patents

Abstract

The invention uses a rhodium compound as a oxo synthesis catalyst, a tin compound as a stabilizer, and a hydrocarbyl iodide as a cocatalyst to form a catalytic system for preparing acetic acid by carbonylation of methanol and carbonylation of methyl acetate to prepare acetic anhydride. In the methanol carbonylation reaction, the system can convert methanol into acetic acid at a high speed and high selectivity under relatively low temperature conditions; in the methyl acetate carbonylation reaction, the catalytic system can also stably catalyze methyl acetate Carbonylation to produce acetic anhydride.

Description

A kind of oxo synthesis catalytic system and application

technical field

The invention relates to a oxo synthesis catalytic system.

The present invention also relates to the application of the above catalyst system in the preparation of acetic acid and acetic anhydride by oxo synthesis.

Background technique

In the 1970s, Paulik et al. of Monsanto Company invented a homogeneous rhodium oxo catalyst (US 3769329), which opened up a new implementation path for carbon monoxide and methanol oxo synthesis to prepare acetic acid under the action of a catalyst. After continuous improvement and perfection, the oxo synthesis technology using rhodium as a catalyst has become the process production route with the largest output in the acetic acid industry.

In the current industrial production, rhodium square planar negative ion structure complex [Rh(CO) ₂ I ₂ ] ^- is often used as the catalytic active species. Although this type of catalyst structure pattern has good catalytic activity, it has the disadvantage of being easily converted into trivalent rhodium [Rh(CO) ₂ I ₄ ^] -anion complexes and generating precipitated RhI ₃ and losing activity, especially at temperature This is especially true at higher temperatures, especially at lower carbon monoxide partial pressures during catalyst separation cycles, but higher temperatures favor the reaction, and lower carbon monoxide partial pressures during separation are characteristic of the flash process. In addition, in order to increase the solubility of the catalyst in the acetic acid production process, it is necessary for the reaction system to maintain a higher water and hydroiodic acid content so as to maintain a higher reactivity of the system [EP55618, EP161874], but therefore accelerates the water gas reaction and consumes The raw material is carbon monoxide, and the strong corrosive reaction medium increases the requirements for equipment materials, and the large amount of water in the system also increases the complexity of the product post-treatment process.

For a long time, further improving the stability of [Rh(CO) ₂ I ₂ ] ^- as a catalytically active species in the reaction and reducing the water content in the reaction system has been one of the most important contents in the research of acetic acid catalysts for methanol carbonylation. Significant progress has been made. The more effective method is to use small molecules or polymer ligands containing nitrogen, phosphorus, oxygen, and sulfur functional groups to form complexes with Rh as catalyst precursors to improve the stability of rhodium active species and improve their catalytic activity. For example, the use of polymers as catalyst ligands (CN100750, US 5281359, US 6458996) enables the catalyst to maintain a high carbonylation activity while certain properties such as optimizing the proportion of the medium in the reaction system, especially the catalyst The thermal stability is also improved.

In a large number of various catalyst researches, the selection of active metals except rhodium, many transition metals such as iridium, ruthenium, nickel, cobalt have been studied, and progress is also made, wherein the iridium catalyst system (EP 849249; US 5672743) had the best effect, resulting in a great improvement in the reaction performance of the catalyst.

The research on improving the performance of the rhodium catalytic system by using a metal salt stabilizer has also achieved considerable results. For example, (EPAppl 0161874, 1985; JP 60-239434, 1985) improved the stability of the catalyst and accelerated the oxidative addition of MeI to a certain extent by adding an iodine salt with a higher content of alkali metal (lithium or sodium) Speed (the rate-controlling step of reaction), greatly reduced the water content in the acetic acid production process simultaneously, wherein the promoting effect of lithium iodide is particularly remarkable. Through the action of iodized salt, the same reactivity can be obtained at lower water content as that at high water content, which improves the utilization efficiency of CO. But in the catalytic reaction system that this kind of high iodine concentration produces acetic acid, may cause the concentration of residual iodine in the product acid to be higher, and then can cause the poisoning of catalyst (Applied Catalysis A: 221 (2001) 253-265). In addition to alkali metal iodide salts, good progress has been made in the research on other different types of catalyst accelerators (US 5922911) and transition metal salt stabilizers, such as (US 5218143) using LiI stabilizers supplemented by VI B group metal salts , that is, use low-valence molybdenum, chromium, tungsten acetate or iodine salt as co-stabilizer, or use Mo(CO) ₆ , W(CO) ₆ , Cr(CO) ₆ carbonyl compound as co-stabilizer, in Good results have also been obtained in the carbonylation of methanol to acetic acid.

Formally, the carbonylation of methanol to acetic acid is very similar to the carbonylation of methyl acetate to acetic anhydride, but there are still big differences between the two reaction systems [Catal.Today 18 (1993) 325-354]. The driving force ΔG ⁰ of the synthesis of acetic anhydride reaction is much smaller than that of methanol carbonylation to acetic acid, which is the thermodynamic reason that it is difficult to realize the carbonylation of methyl acetate into acetic anhydride, and the higher the CO pressure, the more favorable the reaction[ Catal. Today 1992, 13:73-91].

In addition, the reaction of synthesizing acetic anhydride needs to be carried out under the condition that the system is substantially anhydrous, and needs to add a large amount of iodized salt promoters or other promotors except methyl iodide, such as iodonium salts of quaternary amines, quaternary phosphines or alkali metals and Other transition metal additives. Alkali metal salts, especially lithium iodide, pyridine and phosphine can stabilize the catalytically active species [Rh(C0) ₂ I ₂ ] ^- anion; CO/H ₂ mixed gas needs to be introduced into the system to make it deactivated by oxidation at high temperature Rh ^III is reduced to the Rh ^I active state, etc., and at least one or two transition metals need to be added as a joint catalyst [Applied Homogeneous: Catalysis with Organometallic Compounds, Vol.1, VCH, New York, 1996, 116]. Gerhard Luft and Manfred Schrod studied the carbonyl synthesis of acetic anhydride from methyl acetate in the presence of organic compounds containing nitrogen and phosphine and methyl iodide. The results showed that Rh had the highest activity, Ru and Pd were low-activity transition metals, and Pt, Os, Ni has the lowest activity, and its catalytic activity sequence is: Rh>Ir>Ru>Pd>Pt>Os>Ni [J.Mol.Catal., 1983, 20:175]. Although people have done detailed research on the carbonylation of transition metal methyl acetate such as Rh, Pd, Ru, Ni, and Co to synthesize acetic anhydride, only the rhodium catalyst system has better catalytic efficiency and has been applied to industrial production. On the basis of the continuous development of methanol carbonylation to acetic acid and methyl acetate carbonylation to acetic anhydride, BP applied the rhodium catalyst system in 1988 to realize the industrialization of the carbonylation of methyl acetate/water mixture to co-produce acetic acid and acetic anhydride Production [Applied Homogeneous: Catalysis with Organometallic Compounds, Vol. 1, VCH, New York, 1996, 123].

Contents of the invention

The object of the present invention is to provide a catalytic system for oxo synthesis.

In order to achieve the above object, the oxo synthesis catalyst system provided by the present invention is made up of catalyst, promoter and stabilizer, wherein the catalyst is a rhodium compound, the promoter is methyl iodide, and the stabilizer is an inorganic or organotin compound; in the reaction system, The concentration of the catalyst is 200-2000ppm in terms of rhodium, the concentration of the promoter is 200-3000ppm in terms of lithium, and the concentration of the stabilizer is 200-2000ppm in terms of tin.

The oxo synthesis catalytic system, wherein the rhodium compound is: RhCl ₃ , RhBr ₃ , RhI ₃ , Rh(OAc) ₂ , [Rh(CO) ₂ Cl] ₂ , [Rh(CO) ₂ Br] ₂ or [Rh (CO) ₂ I] ₂ .

The oxo synthesis catalyst system, wherein the inorganic tin compounds are: SnX, SnX ₂ , SnX ₄ ; wherein X=Cl, Br, I and other inorganic acid radicals or oxygen group elements.

The oxo catalyst system, wherein the inorganic tin compound is: SnCl ₂ , SnCl ₄ , SnBr ₂ , SnBr ₄ , SnI ₂ , SnI ₄ , pertinyl sulfate, stannous sulfate or tin sulfide.

The oxo synthesis catalyst system, wherein the organotin compound is: tetrahydrocarbyl tin compound, its expression is R ₄ Sn, trihydrocarbyl tin compound, its expression is R ₃ SnX, dihydrocarbyl tin compound, its expression is R ₂ SnX ₂ or a hydrocarbon tin compound, its expression is RSnX ₃ ; R in the expression is a hydrocarbon group, and X is an inorganic or organic acid radical, oxygen or a halogen element.

In the oxo synthesis catalytic system, the hydrocarbon group is an alkyl group or an aryl group.

The above catalytic system provided by the present invention can be applied in the oxo synthesis reaction to prepare acetic acid and acetic anhydride.

When catalyzing methanol carbonylation to produce acetic acid, the reactant methanol or product acetic acid are used as solvents in the reaction system; when catalyzing methyl acetate carbonylation to produce acetic anhydride, the reaction system uses acetic acid, reactant methyl acetate and product acetic anhydride as solvents.

When catalyzing carbonylation to prepare acetic acid, the reaction temperature is 150-180°C, and the pressure of carbon monoxide is 3.0-5.0Mpa; when catalytic carbonylation is used to prepare acetic anhydride, the reaction temperature is 150-220°C, and the pressure of carbon monoxide is 4.0-6.0Mpa, in which hydrogen and carbon monoxide The partial pressure ratio is 2-10%.

The invention improves the stability of the catalyst and simultaneously improves its catalytic activity to a certain extent by adding a stabilizer with excellent performance. In particular, the simplification of the catalytic system can be achieved while improving the stability of the active species. The catalytic system can not only catalyze the carbonylation of methanol to acetic acid at a high speed and high selectivity under relatively mild conditions, but also stably catalyze the carbonylation of methyl acetate to acetic anhydride.

The novel inorganic and organic tin compound additive provided by the invention can significantly improve the catalytic performance, especially the stability, of the catalytic system with rhodium as the active species. The reason for this is not bound by any existing theoretical explanation, but is perhaps related to some interaction between the catalytically active species and the stabilizer atom (or its carbonyl compound).

The main features of the catalytic system provided by the invention are:

① The system can efficiently catalyze the carbonylation reaction of methanol to generate acetic acid without adding additional water.

② Even if water is formed during the above reaction process, only a very small amount of water gas reaction with CO occurs, and there is no detectable water gas reaction in the system (<0.03mol% CO ₂ is generated in a small number of experiments). The reaction temperature is low, and the acetic acid can be obtained by keeping the temperature below 160°C, with high reactivity and good selectivity.

③ The system can stably catalyze the carbonylation of methyl acetate into acetic anhydride without adding additives such as quaternary amines, quaternary phosphines and transition metal salts.

④ For the reaction system of carbonylation of methyl acetate to acetic anhydride, maintaining a certain hydrogen content in the reaction system is conducive to the formation of acetic anhydride. Usually, when the reaction is carried out in a closed reactor, the hydrogen content in the reactor is kept at 0.1~ Between 0.5MPa, the mixed gas of CO and _H2 is fed to the continuous reaction device, and the hydrogen content is between 1 and 10%.

⑤ In the reaction system of the catalyst catalyzing methanol carbonylation to prepare acetic acid and catalyzing methyl acetate carbonylation to acetic anhydride in the present invention, the content of acetic acid is between 30% and 80% (Wt) of the reaction medium. Acetic acid is an excellent solvent, which can not only make the chemical compatibility between the main components in the reaction system better, but also increase the solubility of the catalyst in the reaction medium, and also significantly induce and promote the carbonylation reaction Therefore, it is conducive to the improvement of the catalytic reaction rate.

6. In the reaction system of the present invention, the catalyst catalyzes the carbonylation of methanol to prepare acetic acid, and catalyzes the carbonylation of methyl acetate to synthesize acetic anhydride. No complicated catalyst precursor pretreatment is required. The formation of the catalytic system is simple and rapid, and the catalytic process is convenient and easy. OK.

Detailed ways

Example 1

Add 0.150g of [Rh(CO) ₂ Cl] ₂ , 0.79mol of methanol, 1.12mol of acetic acid, 0.20mol of methyl iodide, and 0.5g of stannous iodide into the autoclave; heat up to 160°C after introducing CO, and stir at 500°C rpm, the reaction pressure was maintained at 5.0 MPa, and the reaction time was 18 minutes. The conversion rate of methanol was 89.1%, and the space-time yield of acetic acid was 21.2mol AcOH/(L·h).

Example 2

Add 0.160 g of Rh(OAc) ₂ , 0.79 mol of methanol, 1.12 mol of acetic acid, 0.20 mol of methyl iodide, and 0.5 g of tin iodide into the autoclave; after introducing CO, the temperature is raised to 150° C., and the stirring speed is 500 rpm. The reaction pressure was maintained at 4.0 MPa, and the reaction time was 20 min. The conversion rate of methanol was 92.0%, and the space-time yield of acetic acid was 19.8 mol AcOH/(L·h).

Example 3

Add 0.330 g of RhBr ₃ , 0.72 mol of methanol, 1.12 mol of acetic acid, 0.20 mol of methyl iodide, and 0.5 g of tin tetrabromide into the autoclave; after introducing CO, the temperature is raised to 150 ° C, the stirring speed is 500 rpm, and the reaction pressure is kept 3.5Mpa, the reaction time is 21min. The conversion rate of methanol was 90.2%, and the space-time yield of acetic acid was 18.5mol AcOH/(L·h).

Example 4

Add [Rh(CO) ₂ I] ₂ 0.210g, methanol 0.79mol, acetic acid 1.12mol, iodomethane 0.15mol, dibutyltin diacetate 0.5g into the autoclave; after feeding CO, heat up to 180°C, stirring at 500°C rev/min, the reaction pressure is maintained at 3.0Mpa, and the reaction time is 15min. The conversion rate of methanol was 63.3%, and the space-time yield of acetic acid was 17.4mol AcOH/(L·h).

Example 5

Add 0.225 g of [Rh(CO) ₂ Br] ₂ , 0.53 mol of methyl acetate, 0.52 mol of acetic acid, 0.23 mol of methyl iodide, and 0.030 mol of lithium iodide into the autoclave. Tarotin iodide 0.5g; After passing in hydrogen gas at 0.1MPa, pass in CO, raise the temperature to 150°C, keep the reaction pressure at 4.0MPa, stir at 500 rpm, and react for 20min. The conversion rate of methyl acetate was 24.6%, and the space-time yield of acetic anhydride was 4.0 mol/L·h.

Example 6

0.30 g of RhI ₃ , 0.53 mol of methyl acetate, 0.52 mol of acetic acid, 0.23 mol of methyl iodide, 0.030 mol of lithium iodide, and 1.0 g of tin iodide were added to the autoclave. After feeding hydrogen at 0.2 MPa, feed CO, raise the temperature to 170°C and keep the total reaction pressure at 4.5 MPa, the stirring speed is 500 rpm, the reaction time is 17 min, the conversion rate of methyl acetate is 33.5%, and the space-time yield of acetic anhydride is 6.5 mol /L·h.

Example 7

0.20 g of Rh(OAc) ₂ , 0.53 mol of methyl acetate, 0.52 mol of acetic acid, 0.23 mol of methyl iodide, 0.030 mol of lithium iodide, and 1.5 g of tin iodide were added to the autoclave. After feeding hydrogen at 0.5 MPa, feed CO, raise the temperature to 190°C and keep the total reaction pressure at 5.5 MPa, the stirring speed is 500 rpm, the reaction time is 15 min, the conversion rate of methyl acetate is 40.3%, and the space-time yield of acetic anhydride is 8.5 mol /L·h.

Example 8

0.15 g of RhCl ₃ , 0.53 mol of methyl acetate, 0.52 mol of acetic acid, 0.23 mol of methyl iodide, 0.030 mol of lithium iodide, and 1.5 g of stannous iodide were added to the autoclave. After introducing hydrogen gas at 0.3 MPa, CO was introduced, the temperature was raised to 180° C., the total reaction pressure was maintained at 6.0 MPa, the stirring speed was 500 rpm, and the reaction time was 20 minutes. The conversion rate of methyl acetate was 48.7%, and the space-time yield of acetic anhydride was 7.8mol/L·h.

Example 9

0.25 g of RhI ₃ , 0.53 mol of methyl acetate, 0.52 mol of acetic acid, 0.23 mol of methyl iodide, 0.030 mol of lithium acetate, and 0.5 g of dibutyltin diacetate were added to the autoclave. After introducing hydrogen gas at 0.3 MPa, CO was introduced, the temperature was raised to 220° C., the total reaction pressure was maintained at 5.0 MPa, the stirring speed was 500 rpm, and the reaction time was 18 minutes. The conversion rate of methyl acetate was 46.7%, and the space-time yield of acetic anhydride was 8.2mol/L·h.

Claims (1)

1. the application of hydroformylation catalytic system in the reaction of catalytic methylester acetate oxo-acetic anhydride is characterized in that, adds catalyst RhCl in autoclave pressure ₃0.15g, methyl acetate 0.53mol, acetic acid 0.52mol, co-catalyst iodomethane 0.23mol, co-catalyst lithium iodide 0.030mol, stabilizing agent stannous iodide 1.5g; After feeding hydrogen 0.3MPa, feed CO, be warming up to 180 ℃, keep reaction gross pressure 6.0MPa, 500 rev/mins of mixing speeds, reaction time 20min, the methyl acetate conversion ratio that obtains is 48.7%, the aceticanhydride space-time yield is 7.8mol/Lh.