CN107999061B - Preparation method and application of efficient catalyst for preparing aldehyde by olefin hydroformylation - Google Patents

Abstract

The invention provides a preparation method of a high-efficiency catalyst for preparing aldehyde by olefin hydroformylation, wherein the catalyst is a supported catalyst and consists of a carrier and an active center, the carrier is a magnesium silicate nanotube with huge specific surface area, and the active center is nano metal rhodium; the preparation method of the catalyst comprises the following steps: and (3) dipping the active center precursor on a carrier by adopting a dipping method, and then drying and reducing to obtain the heterogeneous catalyst. Active center Rh in the present invention⁰The method is different from the traditional reduction method and is directly obtained by low-temperature calcination under protective gas. Compared with the traditional homogeneous catalyst, the catalyst provided by the invention has the characteristics of good catalytic performance, easy separation, prolonged service life and recycling use in the liquid phase reaction of preparing aldehyde by olefin hydroformylation, and has wide industrial application value.

Description

Preparation method and application of efficient catalyst for preparing aldehyde by olefin hydroformylation

Technical Field

The technical scheme of the invention relates to the field of preparation methods of supported catalysts, and particularly relates to a preparation method of a high-efficiency catalyst for preparing aldehyde by olefin hydroformylation.

Background

The hydroformylation reaction, also called OXO reaction, is one of the most important reactions in the chemical homogeneous catalysis industry at present, and the chemical reaction process is to generate aldehyde with one more carbon atom by the addition of olefin, carbon monoxide and hydrogen under certain conditions of catalyst, temperature and pressure. The hydroformylation aldehyde product is a key raw material and an important organic synthesis intermediate for preparing chemical products such as various solvents, plasticizers, surfactants and the like. In addition, chiral products can be synthesized from hydroformylation of asymmetric olefins, which is valuable in the synthesis of pharmaceuticals, pesticides, and natural products. High regioselectivity control of functionalized olefin hydroformylation is one of the hotspots in the research field, and the electronic effect and the stereo effect of the ligand are modulated to realize the regulation and control of the normal and isomeric ratio and chirality of the product aldehyde.

For hydroformylation catalytic reaction systems, an important technical problem is the separation of the catalyst from the product and the prevention of loss of active components. Currently, the olefin hydroformylation reaction is mainly based on a homogeneous catalytic system in industry. Although the olefin hydroformylation homogeneous catalysis system has the advantages of high catalytic activity, good selectivity, mild reaction condition and the like; however, the dissolution of the transition metal complex catalyst used in the catalytic reaction into the hydroformylation product and the organic solvent used in the reaction causes difficulties in separating the product from the transition metal complex catalyst, particularly the separation of the metal complex catalyst from the high boiling product, which may result in the annual loss of several million euros in a hydroformylation plant using an Rh-based catalyst at an energy yield of 400kt/a, although only 1 ppm of Rh is carried away per kg of product. Such as rhodium-tertiary phosphine method (US Pat.3527809, US Pat. 4247486, US Pat.5105018) of united carbon (UCC) company and mitsubishi chemical synthesis company, etc., the catalyst has higher activity, selectivity and milder reaction conditions, but the product aldehyde and the catalyst are in a uniform liquid phase, and the separation of the product from the catalyst and the recovery of the catalyst generally adopt distillation or reduced pressure distillation (such as US patent No. 4528403), which is not suitable for catalysts which are easily decomposed by heating, especially for hydroformylation of high carbon olefins, the boiling point of the product aldehyde is higher, and the method of separating the catalyst by distillation often causes problems of product polymerization, catalyst decomposition and deactivation, etc. The water-soluble rhodium-phosphine compound catalyst is easy to separate from a product, the process flow is simple, but due to the fact that the mass transfer efficiency of two-phase reaction is low, such as US Pat.4248802, the addition of a phase transfer agent can cause the separation problem, and even emulsification can be caused to increase the difficulty of phase separation.

The heterogeneous catalyst has the advantages of easy separation and easy recovery when the metal nanoparticles are immobilized on the carrier, but the activity and selectivity in the hydroformylation reaction are low, thereby greatly hindering the industrial application. The technical scheme disclosed in CN10144475A adopts haloalkyl trimethylsilane and lithium diphenylphosphine as coupling agents to immobilize the rhodium complex on the mesoporous molecular sieve or nano-silica, the catalyst active group prepared by the method is firmly immobilized and not easy to run off, and the catalyst and the product can be well separated, but the catalyst activity is lower, resulting in low conversion rate of olefin.

Therefore, it is necessary to develop a new hydroformylation catalyst having high activity and high selectivity, and having good stability, which is suitable for industrial application. The magnesium silicate nanotubes (MgSNTs) have higher Specific Surface Area (SSA) and one-dimensional tubular structure, can effectively disperse and support metal active components, improve the reaction activity and stability of the catalyst, and can overcome the defect that the catalyst and a product are difficult to separate in a homogeneous system.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: provides a preparation method of a high-efficiency catalyst for preparing aldehyde by olefin hydroformylation. The method takes magnesium silicate nanotubes as a carrier and adopts an impregnation-reduction method to prepare the olefin hydroformylation catalyst with high reaction activity and stability. So as to overcome the defect that the catalyst and the product are difficult to separate in the traditional homogeneous system; so as to overcome the defects of lower catalyst activity and the like.

The technical scheme adopted by the invention for solving the problem is as follows:

a preparation method of a high-efficiency catalyst for preparing aldehyde by olefin hydroformylation comprises the following steps:

(1) taking 3.5 parts of rhodium trichloride aqueous solution with the concentration of 0.002 g/ml water for later use;

(2) putting 1g of magnesium silicate nanotube into a flask, and adding 20-50 ml of deionized water for later use;

(3) adding the solution prepared in the step (1) into the flask in the step (2) under the stirring condition, and stirring at normal temperature for 6-24 hours;

(4) centrifuging the mixture obtained in the step (3), and drying the mixture for 12-36 hours in an air atmosphere at the temperature of 333-353K;

(5) transferring the obtained powder into a tubular furnace, and calcining under a protective atmosphere at 573K at a heating rate of 10K/min for 2-4 hours to obtain a product, namely a magnesium silicate nanotube-loaded rhodium catalyst;

(6) after the catalytic reaction is finished, centrifuging the reaction solution, washing with ethanol for 3 times, and drying to obtain a recyclable catalyst;

the protective atmosphere in the step (5) of the technical scheme can be nitrogen, argon and CO₂。

The invention has the following advantages:

1. the magnesium silicate nanotube loaded rhodium catalyst obtained by the method is provided. The magnesium silicate nanotube has higher specific surface area and pore volume, and is beneficial to the exposure of catalytic active sites and the diffusion of a substrate. As shown in FIG. 3, rhodium nanoparticles are uniformly distributed on the surface and inside of magnesium silicate nanotubes, and the size of the metal active center is uniform and is about 1-3 nm.

2. The method adopted by the invention is simple and effective, has less process steps, and Rh⁰The catalyst is directly obtained by a low-temperature calcination method, is green and environment-friendly, and has low cost.

3. The raw materials of magnesium nitrate, sodium silicate, sodium hydroxide and rhodium chloride adopted by the invention are common chemical reagents, and are cheap and easy to obtain.

4. The catalyst prepared by the invention is suitable for mass production and can be used for industrial mass production.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a representation of nitrogen adsorption and pore size distribution of the support material described in example 1;

FIG. 2 is an XRD spectrum of a magnesium silicate nanotube supported rhodium catalyst in example 1, wherein (A) is a product before being supported and (B) is a product after being supported.

FIG. 3 is a TEM spectrum of the magnesium silicate nanotube-supported rhodium catalyst of example 1, wherein (A) is the product before supporting and (B) is the product after supporting.

FIG. 4 shows XPS measurements of the rhodium nanoparticles as active centres for the catalyst obtained in example 1.

Detailed Description

Example 1

(1) Dissolving 0.0009mol of rhodium trichloride in a flask containing 100ml of water to prepare a rhodium trichloride aqueous solution for later use;

(2) dispersing 1g of magnesium silicate nanotubes into a flask containing 10ml of water for later use;

(3) adding 6.5ml of the solution prepared in the step (1) into the flask in the step (2) under the stirring condition, and carrying out immersion stirring reaction for 6 hours;

(4) then, centrifugally separating the mixture obtained in the step (3), and drying the mixture for 12 hours in an air atmosphere at the temperature of 333K;

(5) transferring the obtained powder into a tubular furnace, calcining the powder in a nitrogen atmosphere at 573K, at a heating rate of 10K/min for 2 hours to obtain a product of about 1g of magnesium silicate nanotube-supported rhodium catalyst;

(6) weighing a certain amount of the obtained catalyst, reaction substrates of vinyl acetate and solvent of toluene, adding the catalyst, the reaction substrates of vinyl acetate and solvent of toluene into a high-pressure reaction kettle for a catalytic experiment, and calculating the catalytic activity of the catalyst according to gas phase data.

According to TEM test, the product is magnesium silicate nanotube structure with rhodium nanoparticles with uniform size dispersed on the surface and inside.

Example 2

The temperature of 573K in step (5) in example 1 was changed to 523K. The other steps are the same as in example 1. The product obtained was the same as in example 1.

Example 3

The temperature at 573K in step (5) in example 1 was changed to 623K. The other steps are the same as in example 1. The product obtained was the same as in example 1.

Example 4

The immersion stirring in step (3) in example 1 was changed to immersion stirring for reaction for 24 hours, and the other steps were the same as in example 1. The product obtained was the same as in example 1.

Example 5

The temperature of 333K in step (4) in example 1 was changed to 353K. The other steps are the same as in example 1. The product was obtained as in example 1.

Example 6

The drying time in step (4) in example 1 was changed to 36 hours, and the other steps were the same as in example 1. The product obtained was the same as in example 1.

Example 7

The calcination time in step (5) in example 1 was set to 4 hours, and the other steps were the same as in example 1. The product obtained was the same as in example 1.

Examples 8 to 9

The nitrogen gas in the step (5) in example 1 was changed to argon gas and CO₂The other steps are the same as in example 1. The product obtained was the same as in example 1.

Example 10

The catalyst obtained in example 1 was reacted, centrifuged and recovered, washed with ethanol 3 times, and vacuum dried at 50 ℃ for 2 hours. Example 10 was obtained.

Example 11

The catalyst obtained in example 10 was reacted, centrifuged and recovered, washed with ethanol 3 times, and vacuum dried at 50 ℃ for 2 hours. Example 11 was obtained.

Example 12

The catalyst obtained in example 11 was reacted, centrifuged and recovered, washed with ethanol 3 times, and vacuum dried at 50 ℃ for 2 hours. Example 12 was obtained.

Example 13

The reaction substrate in step (6) in example 1 was changed to cyclohexene, the solvent was changed to tetrahydrofuran, and the other steps were the same as in example 1. Example 13 was obtained.

Example 14

The reaction substrate in step (6) in example 1 was changed to acrylamide, the solvent was changed to 35ml of toluene and 35ml of tetrahydrofuran, and the other steps were the same as in example 1. Example 14 was obtained.

Evaluation the above catalyst catalyzed hydroformylation of olefins in a GS-0.25 type autoclave. In particular toThe experimental steps are as follows: 5ml of the reaction substrate, 0.4g of the catalyst and 65ml of the reaction solvent were placed in an autoclave, which was then closed. Firstly, a certain amount of CO gas is introduced to replace the air in the kettle, and the air is charged and discharged twice. After the replacement is finished, filling CO and H with total pressure of 6 volume ratio 1: 1₂. And after the pressure is stable, starting the heating device and the stirring device. When the temperature is close to 100 ℃, the heating voltage is reduced, and the reaction is carried out under the set constant temperature condition. And stopping the reaction after the preset reaction time is reached, and cooling the reaction kettle to room temperature. The gas in the reaction kettle is discharged, the high-pressure kettle is opened in a fume hood, the reaction mixed liquid is taken out (after the catalyst and the reaction liquid are separated by centrifugal treatment), and a reaction sample is qualitatively analyzed by 6C-MS and quantitatively analyzed by Shimadzu GC-2014. The specific chromatographic conditions were as follows: the injector temperature was 255 ℃ and the detector temperature was 260 ℃ with a SE-30 capillary column. The temperature programming strip comprises: the initial temperature is 100 ℃, the temperature is maintained for 3min, then the temperature is raised to 150 ℃ at the speed of 10 ℃/min, and then the temperature is raised to 250 ℃ at the speed of 25 ℃/min, and the temperature is maintained for 5 min.

TABLE 1 olefin hydroformylation Performance of novel magnesium silicate nanotubes Supported rhodium catalysts

Catalyst numbering	Conversion rate%	Total selectivity of aldehyde produced%	Branch to straight
				Example 1	100	80.02	100∶0
Example 10 (first)Second circulation)	95	73.20	100∶0
				Example 11 (second cycle)	88.4	70.68	100∶0
Example 12 (third cycle)	70.36	72.12	100∶0
				Example 13	100	82.81	-
Example 14	30.26	26.54	25∶75

From the results in the table, the novel supported catalyst for the hydroformylation of olefins provided by the invention has the advantages of simple preparation method, simple reaction process and device, stable reaction performance, high yield, good catalyst recycling result, capability of effectively solving the problems of metal component loss or ligand loss, difficult catalyst recycling and the like in the prior art, and wide industrial application prospect, and can be used for reaction in a conventional high-pressure autoclave reactor.

The present invention has been described in detail above, but the present invention is not limited to the specific embodiments described herein. It will be understood by those skilled in the art that other modifications and variations may be made without departing from the scope of the invention. The scope of the invention is defined by the appended claims.

Claims (1)

1. A preparation method of an aldehyde catalyst by olefin hydroformylation comprises the following steps:

(1) taking 3.5 parts of rhodium trichloride aqueous solution with the concentration of 0.002 g/ml water for later use;

(2) putting 1g of magnesium silicate nanotube into a flask, and adding 20-50 ml of deionized water for later use;

(3) adding the solution prepared in the step (1) into the flask in the step (2) under the stirring condition, and stirring at normal temperature for 6-24 hours;

(4) centrifuging the mixture obtained in the step (3), and drying the mixture for 12-36 hours in an air atmosphere at the temperature of 333-353K;

(5) transferring the obtained powder into a tubular furnace, calcining in a protective atmosphere at 573K, at a heating rate of 10K/min for 2-4 hours to obtain a product, namely a magnesium silicate nanotube-loaded rhodium catalyst, wherein rhodium nanoparticles are uniformly distributed on the surface and inside of the magnesium silicate nanotube and have the size of 1-3 nanometers;

(6) after the catalytic reaction is finished, centrifuging the reaction solution, washing with ethanol for 3 times, and drying to obtain a recyclable catalyst;

the protective atmosphere in the step (5) is nitrogen, argon and CO₂。

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