阅读说明：本技术 一种甲醇羰基化反应用双金属催化剂、其制备方法及应用 (Bimetallic catalyst for methanol carbonylation reaction, preparation method and application thereof ) 是由 邵守言 闫丰文 朱桂生 代松涛 黄志军 王忠华 袁国卿 刘玲 赵禄强 唐丽 于 2020-04-27 设计创作，主要内容包括：本发明一方面公开了一种甲醇羰基化反应用双金属催化剂,其具有如下式所示的结构式：<Image he="515" wi="700" file="DDA0002469877420000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>其中,m＝1,2,3,n＝0,1,2。本发明还公开了上述甲醇羰基化反应用双金属催化剂的制备方法及其在甲醇羰基化合成醋酸和醋酸酐中的应用。本发明提供的甲醇羰基化反应用双金属催化剂,由于配合物体系中同时存在锂、铑双金属体系,特殊的双金属协同作用使得催化剂表现出优良的催化活性和反应稳定性。(The invention discloses a bimetallic catalyst for methanol carbonylation reaction, which has a structural formula shown as the following formula:)

1. A bimetallic catalyst for methanol carbonylation reactions having the formula:

wherein m is 1, 2, 3, n is 0, 1, 2.

2. The bimetallic catalyst for methanol carbonylation according to claim 1, wherein: the catalyst is prepared by taking a pyridine-lithium compound shown as the following formula as a ligand and carrying out coordination reaction with dichlorotetracarbonyl dirhodium:

wherein m is 1, 2, 3, n is 0, 1, 2.

3. A method of preparing the bimetallic catalyst for methanol carbonylation reaction according to claim 2, comprising the steps of:

dissolving 1 molar part of pyridine-lithium compound in 50-200 molar parts of methanol, and stirring in an ice bath;

adding 0.5 molar part of dichloro tetracarbonyl dirhodium, and continuing stirring for 5-20 minutes;

adding a precipitator for precipitation, and filtering to obtain the bimetallic catalyst.

4. The method of claim 3, wherein the bimetallic catalyst is selected from the group consisting of: the precipitant is diethyl ether.

5. The use of the bimetallic catalyst for methanol carbonylation according to claim 1, in the synthesis of acetic acid by methanol carbonylation, wherein:

adding the bimetallic catalyst, methanol, a cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide, keeping the pressure of the carbon monoxide at 3-4 MPa,

stirring and reacting at the reaction temperature of 150-200 ℃ to obtain acetic acid;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 200-3000 PPm.

6. The use of a bimetallic catalyst for methanol carbonylation according to claim 5, in the synthesis of acetic acid by methanol carbonylation, wherein: the cocatalyst is methyl iodide, and the amount of the cocatalyst in the reaction system is 0.1-5 mol/L.

7. The use of the bimetallic catalyst for methanol carbonylation according to claim 1, in the synthesis of acetic anhydride by methanol carbonylation, wherein:

adding the bimetallic catalyst, methyl acetate, cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide to replace air in the pressure kettle, then continuously introducing the carbon monoxide, adding hydrogen, and keeping the pressure of the mixed gas of the carbon monoxide and the hydrogen at 3.5-4.5 MPa;

stirring and reacting at the reaction temperature of 170-200 ℃ to obtain acetic anhydride;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 400-2000 PPm.

8. The use of a bimetallic catalyst for methanol carbonylation according to claim 7, in the synthesis of acetic anhydride by methanol carbonylation, wherein: the catalyst promoter comprises methyl iodide, and the amount of the methyl iodide in the reaction system is 0.1-5 mol/L.

9. The use of a bimetallic catalyst for methanol carbonylation according to claim 8, in the synthesis of acetic anhydride by methanol carbonylation, wherein: the cocatalyst also comprises a pyridine-lithium compound shown as the following formula, the molar ratio of the pyridine-lithium compound to the bimetallic catalyst is 1-1000: 1,

wherein m is 1, 2, 3, n is 0, 1, 2.

10. The use of a bimetallic catalyst for methanol carbonylation according to claim 7, in the synthesis of acetic anhydride by methanol carbonylation, wherein: the volume content of the hydrogen is 1-10% based on the total volume of the carbon monoxide and the hydrogen.

Technical Field

The invention relates to the technical field of carbonylation synthesis of acetic acid and acetic anhydride, in particular to a bimetallic catalyst for carbonylation synthesis of acetic acid from methanol and carbonylation synthesis of acetic anhydride from methyl acetate, and a preparation method and application of the catalyst.

Background

The invention of Paulik et al (US 3769329) of Monsanto company in the early 70 th century is that methanol and carbon monoxide are carbonylated under the action of homogeneous rhodium catalyst to prepare acetic acid, and this invention opens up a new important technological route for the oxo synthesis of methanol. On the basis of this, the subsequent Halcon (BE 819455) Ealtman, Ajinamoto (Japan Kokai 50-30,820), Showa Denko (Japan Kokai 50/47,922), BP (B.Von Schlotheim, chem.Industrie 1994, 9/89.80) and Hoechst (DE 2450965) will be identical [ Rh (CO ]₂I₂]^-The research of the active species of the catalyst in the form of negative ion structure for preparing acetic anhydride by carbonylation of methyl acetate has made a breakthrough.

With continued improvement and sophistication, the use of homogeneous rhodium as a catalyst for the carbonylation of methanol and methyl acetate has become the world's most important process route for the production of acetic acid and acetic anhydride. The catalyst has high activity and good selectivity, and is an obvious advantage of the catalyst; however, the instability of such catalysts, which tend to form precipitates of trivalent rhodium, especially at higher temperatures which favor the reaction, or even when the partial carbon monoxide pressure in the flash-separated part is reduced, is well recognized.

The design of catalyst structures and the improvement of reaction systems have been the subject of intense research for a long time, and a large number of research papers and patent patents are published every year. Much research has centered around the choice of catalyst ligands; or with non-rhodium metal active species; or different additives are added into the reaction system, and the activity and stability of the existing catalyst are improved by selecting the novel additive, so that the aim is to obtain a novel catalyst system which is superior to the existing industrial catalyst.

In the selection of the catalyst ligands, many attempts have been made to use phosphine-containing compounds as ligands, for example, in J.Rankin et al, by [ RhCl (CO) (PEt)₃)₂]The complex reacts at 150 ℃ at a reaction rate STY (mol AcOH/L.h) of [ Rh (CO ]₂Cl₂]₂5.0 (STY-space-time yield) to 9.2(chem. Commun.1997, 1835); c.a Carral et al selected bidentate phosphine complexes whose STY reached 13.7(chem.commun.2000, 1277); c.m. thomas et al, TON (conversion number) 732(chem.eur.j., 2002.8, 3343), a catalytic rate for the carbonylation of methanol to acetic acid with a phosphine rhodium complex; freixa et al, the catalytic rate of the cis phosphine rhodium dicarbonyl complex, TON, reached 902(Angew. chem. int. Ed, 2005, 44, 4305). The study of the coordination of nitrogen-containing compounds is still the focus of the catalyst research, such asPanriaj et al prepared monodentate rhodium azomethide complexes that reached a TON of 1382 at 150 ℃.

In the research of novel catalysts, the addition of an auxiliary agent in a reaction system is an effective method for improving the carbonylation rate. The research of this kind is to improve the performance of the catalyst by adding inorganic salt promoter into the reaction system, wherein the successful example is Hoechst Celanese company, which develops the oxo synthesis process with low water content in the beginning of 20 th century 80 by improving Monsanto process, and the technological advantages of the process are very obvious, and the patent application is US 5001259, EP 055618. Lithium iodide is also the most important catalyst promoter in the reaction system for preparing acetic anhydride by carbonylation of methyl acetate. Joseph R.Zoeller etalcatal.Today, 1992, 13.73-91, et al, reported an acetic anhydride catalysis system from Eastman corporation, discussed the effect of lithium iodide in the reaction, and proposed the reaction mechanism of methyl acetate carbonylation catalyzed by a Li-Rh co-catalysis system.

Disclosure of Invention

The invention aims to provide a bimetallic catalyst for methanol carbonylation reaction, which has high efficiency and good stability in the carbonylation synthesis, a preparation method and application aiming at the defects of the prior art.

In one aspect, the present invention provides a bimetallic catalyst for methanol carbonylation reaction having a formula as shown below:

wherein m is 1, 2, 3, n is 0, 1, 2.

Alternatively, the bimetallic catalyst for methanol carbonylation reaction according to the present invention is formed by coordination reaction of a pyridine-lithium compound represented by the following formula as a ligand with dichlorotetracarbonyldirhodium:

wherein m is 1, 2, 3, n is 0, 1, 2.

In another aspect, the present invention provides a method for preparing the above bimetallic catalyst for methanol carbonylation, comprising the steps of:

dissolving 1 molar part of pyridine-lithium compound in 50-200 molar parts of methanol, and stirring in an ice bath;

adding 0.5 molar part of dichloro tetracarbonyl dirhodium, and continuing stirring for 5-20 minutes;

adding a precipitator for precipitation, and filtering to obtain the bimetallic catalyst.

Alternatively, according to the preparation method of the bimetallic catalyst for methanol carbonylation reaction of the present invention, the precipitant is diethyl ether.

In another aspect, the present invention further provides an application of the above bimetallic catalyst for methanol carbonylation reaction in the synthesis of acetic acid by methanol carbonylation, wherein the application is as follows:

adding the bimetallic catalyst, methanol, a cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide, keeping the pressure of the carbon monoxide at 3-4 MPa,

stirring and reacting at the reaction temperature of 150-200 ℃ to obtain acetic acid;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 200-3000 PPm.

Optionally, according to the application of the bimetallic catalyst for methanol carbonylation reaction in the synthesis of acetic acid through methanol carbonylation, the cocatalyst is methyl iodide, and the usage amount of the cocatalyst in a reaction system is 0.1-5 mol/L.

In another aspect, the present invention further provides an application of the above bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, wherein the application is as follows:

adding the bimetallic catalyst, methyl acetate, cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide to replace air in the pressure kettle, then continuously introducing the carbon monoxide, adding hydrogen, and keeping the pressure of the mixed gas of the carbon monoxide and the hydrogen at 3.5-4.5 MPa;

stirring and reacting at the reaction temperature of 170-200 ℃ to obtain acetic anhydride;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 400-2000 PPm.

Optionally, according to the application of the bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, the cocatalyst comprises methyl iodide, and the amount of the methyl iodide in the reaction system is 0.1-5 mol/L.

Optionally, according to the application of the bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, the cocatalyst also comprises a pyridine-lithium compound shown as the following formula, the molar ratio of the pyridine-lithium compound to the bimetallic catalyst is 1-1000: 1,

wherein m is 1, 2, 3, n is 0, 1, 2.

Optionally, according to the application of the bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, the volume content of hydrogen is 1-10% based on the total volume of carbon monoxide and hydrogen.

According to the bimetallic catalyst for methanol carbonylation provided by the invention, because a lithium and rhodium bimetallic system exists in a complex system at the same time, the catalyst shows excellent catalytic activity and reaction stability due to the special bimetallic synergistic effect.

Detailed Description

The invention is further described below with reference to specific embodiments.

In one aspect, the present invention provides a bimetallic catalyst for methanol carbonylation reaction having a formula as shown below:

wherein m is 1, 2, 3, n is 0, 1, 2. The catalyst takes rhodium as an active species, the rhodium active species and a pyridine-lithium compound form a monodentate coordination structure with the structure, and the catalyst shows excellent catalytic activity and reaction stability due to the special bimetallic synergistic effect of a lithium and rhodium bimetallic system in a complex system.

Preferably, the catalyst is prepared by a coordination reaction of a pyridine-lithium compound shown as the following formula and dichlorotetracarbonyl dirhodium as a ligand:

wherein m is 1, 2, 3, n is 0, 1, 2.

The catalyst selects a pyridine-lithium compound with good stabilizing effect in the oxo synthesis as a ligand, forms a relatively stable structural form with rhodium carbonyl dichloride tetracarbonyl dirhodium, and introduces lithium metal ions to form a bimetallic system, thereby greatly improving the catalytic effect.

In another aspect, the present invention provides a method for preparing the above bimetallic catalyst for methanol carbonylation, comprising the steps of:

dissolving 1 molar part of pyridine-lithium compound in 50-200 molar parts of methanol, and stirring in an ice bath;

adding 0.5 molar part of dichloro tetracarbonyl dirhodium, and continuing stirring for 5-20 minutes;

adding a precipitator for precipitation, and filtering to obtain the bimetallic catalyst.

In the above preparation method, the lithium pyridine-compound may be one or a mixture of more than one of lithium 2-picolinate, lithium 4-picolinate, lithium 2, 4-pyridinedicarboxylate, lithium 2, 4, 6-pyridinetricarboxylate, lithium 2-pyridineacetate, lithium 4-pyridineacetate, lithium 2, 4-pyridinediacetate, lithium 2, 4, 6-pyridinetriacetate, lithium 2-pyridinepropionate, lithium 4-pyridinepropionate, lithium 2, 4-pyridinedipropionate, and lithium 2, 4, 6-pyridinetripropionate.

In the above preparation method, ethers may be used as the precipitant, petroleum ether and diethyl ether are preferably used, and diethyl ether is most preferably used. The amount of the precipitant is generally used in excess relative to the reaction product.

The bimetallic catalyst for methanol carbonylation provided by the invention can be applied to methanol carbonylation to synthesize acetic acid and acetic anhydride. Therefore, the invention also provides the application of the bimetallic catalyst for the methanol carbonylation reaction in the synthesis of acetic acid and acetic anhydride by methanol carbonylation.

The application of the bimetallic catalyst for the methanol carbonylation reaction in the synthesis of acetic acid by methanol carbonylation is as follows:

adding the bimetallic catalyst, methanol, a cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide, keeping the pressure of the carbon monoxide at 3-4 MPa,

stirring and reacting at the reaction temperature of 150-200 ℃ to obtain acetic acid;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 200-3000 PPm.

In the application of the bimetallic catalyst for methanol carbonylation reaction in the synthesis of acetic acid by methanol carbonylation, the cocatalyst is methyl iodide, and the amount of the cocatalyst in a reaction system is 0.1-5 mol/L.

The application of the bimetallic catalyst for the methanol carbonylation reaction in the synthesis of the acetic anhydride by the methanol carbonylation is as follows:

adding the bimetallic catalyst, methyl acetate, cocatalyst and acetic acid into a pressure kettle;

introducing carbon monoxide to replace air in the pressure kettle, then continuously introducing the carbon monoxide, adding hydrogen, and keeping the pressure of the mixed gas of the carbon monoxide and the hydrogen at 3.5-4.5 MPa; the volume content of the hydrogen is preferably 1-10% by taking the total volume of the carbon monoxide and the hydrogen as a reference;

stirring and reacting at the reaction temperature of 170-200 ℃ to obtain acetic anhydride;

wherein the dosage of the bimetallic catalyst in the reaction system is calculated by rhodium, and the rhodium content is 400-2000 PPm.

In the application of the bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, the cocatalyst comprises methyl iodide, and the amount of the methyl iodide in the reaction system is 0.1-5 mol/L.

Preferably, in the application of the bimetallic catalyst for methanol carbonylation reaction in methanol carbonylation synthesis of acetic anhydride, the cocatalyst also comprises the pyridine-lithium compound, and the molar ratio of the pyridine-lithium compound to the bimetallic catalyst is 1-1000: 1, preferably 1-400: 1, and more preferably 1-200: 1. Different from the common carbonylation reaction, the invention adds the pyridine-lithium ligand as an accelerant or a stabilizing agent into the reactor, further introduces lithium salt as a cocatalyst, increases the efficiency and stability of the reaction system, and improves the catalytic effect.

In order to specifically describe the present invention, the applicant illustrated the present bimetallic catalyst for methanol carbonylation reaction and the preparation method thereof by the following examples. It should be understood that the following specific examples are illustrative of specific implementations of the invention only and are not to be construed as limiting the scope of the invention.