A method for evaluating the activity of a rhodium-containing catalyst working solution

Abstract

The present application belongs to the field of catalyst activity evaluation, and particularly relates to a kind of activity evaluation method of rhodium-containing catalyst working solution.The method is realized by the following steps: weighing a certain volume of rhodium catalyst working solution, adding to a high-pressure reaction kettle, then adding triphenylphosphine, olefin and solvent, and immediately sealing the kettle; nitrogen is first introduced into the reaction kettle for replacement, then heated, the stirring is opened, and synthesis gas is introduced, the reaction is timed, after a certain time, the synthesis gas is turned off, the kettle is opened after being cooled to room temperature, the working solution is taken out, introduced into gas chromatography, and the area normalization method is used to calculate the olefin conversion rate and normal isomer ratio of the working solution.The present application simulates the reaction process of rhodium catalyst working solution in a high-pressure reaction kettle, limits the amount of reactants, judges the catalytic ability of rhodium catalyst in the reaction system after a certain time, has low requirement on equipment, is convenient and fast, simple and effective, and has high accuracy of test results.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst activity evaluation, and particularly relates to a method for evaluating the activity of a rhodium-containing catalyst working solution. BACKGROUND

[0002] Rhodium compounds are used as noble metal homogeneous catalysts in important chemical processes such as hydroformylation, hydrogenation, and carbonyl synthesis. Most of the large-scale alcohol carbonylation (mainly butanol / octanol) devices of domestic and foreign petroleum chemical enterprises adopt a low-pressure propylene hydroformylation process. The core of the process is a rhodium catalyst. The process uses propylene and synthesis gas as raw materials to generate mixed butyraldehyde under the action of the rhodium catalyst. The n-butyraldehyde is converted into octyraldehyde (EPA) through a condensation reaction, and the EPA is converted into octanol through hydrogenation. The mixed butyraldehyde is hydrogenated to produce butanol. The carbonylation unit is the core of the butanol / octanol production device. In the reaction process, a homogeneous complex rhodium phosphine catalyst system is used, with rhodium atoms as active centers and triphenylphosphine as a ligand. When an excess of triphenylphosphine is added under certain conditions, the n-iso ratio of the product can be increased to more than 20:1. However, the precious metal rhodium is scarce and has a complex manufacturing process, and the price is very high. In normal production, a small part of the catalyst is taken away with the product, and its activity gradually decreases with the extension of the production cycle and the accumulation of poisons until it is completely deactivated and cannot be used. The designed service life is about 1.5 years.

[0003] Therefore, timely evaluation of the rhodium-containing catalyst working solution in the reactor can directly reflect the activity of the rhodium catalyst, so that the rhodium catalyst in the system can be supplemented or regenerated and recovered in time.

[0004] The existing evaluation method is mainly completed through a parr micro-reactor. A certain mass of rhodium catalyst working solution is weighed, a certain amount of triphenylphosphine, 1-octene, and a solvent are added, synthesis gas is introduced under a certain temperature and pressure, and the temperature, pressure, and synthesis gas consumption rate are tested with respect to the reaction time. However, this method has high requirements for equipment, needs to be customized according to different reaction types, is expensive, and has certain limitations. SUMMARY

[0005] In view of the deficiencies of the existing evaluation method, the present application provides a method for evaluating the activity of a rhodium-containing catalyst working solution. The evaluation method is simple and easy to implement, and overcomes the deficiencies of the existing method, such as high cost and high requirements for equipment.

[0006] The technical scheme adopted by the present application to achieve the above-mentioned purpose is as follows:

[0007] The present application provides a method for evaluating the activity of a rhodium catalyst working solution, comprising the following steps:

[0008] (1) take a certain volume of rhodium catalyst working solution, add to the high pressure reactor, then add triphenylphosphine, olefin and solvent, immediately seal the reactor;

[0009] (2) first introduce nitrogen into the reactor for displacement, then heat, open the stirring, introduce synthesis gas, start the reaction, after a certain time, close the synthesis gas, cool to room temperature, open the reactor, take out the working solution, introduce gas chromatography, calculate the olefin conversion rate and normal isomer ratio of the working solution by area normalization method.

[0010] Further, in step (1), the concentration of rhodium in the rhodium catalyst working solution after dilution is 100-500 ppm.

[0011] Further, in step (1), the mass ratio of triphenylphosphine to rhodium is 50:1-150:1.

[0012] Further, in step (1), the volume ratio of the rhodium catalyst working solution to olefin is 3:1-3; the olefin is liquid normal olefin with a boiling point higher than room temperature; the solvent is butyl aldehyde.

[0013] Further, in step (2), the reaction temperature is 70-80℃; the stirring speed is 500rpm-1500rpm.

[0014] Further, in step (2), the synthesis gas is composed of CO:H2 with a volume ratio of 1:1, and the concentration is 50%-100%.

[0015] Further, in step (2), the reaction conditions are: pressure 1-2MPa, reaction time 0.5-3h.

[0016] Further, in step (2), the gas chromatography conditions are: chromatographic column type: KB-FFAP30m*0.32mm*1um, injection port heater temperature: 300℃, column oven temperature: initial 50℃, hold for 4min, programmed temperature rise 15℃ / min, final temperature 230℃, hold for 15min; chromatographic column flow rate: 1.2ml / min, split ratio: 30:1, detector: FID heater: 300℃, H2: 30ml / min, Air: 400ml / min, tail blow flow nitrogen: 25ml / min.

[0017] Further, in step (2), the formula used in the area normalization method is:

[0018] ;

[0019] In the formula:

[0020]

[0021] The present application is to test the activity and normal-isomer ratio of rhodium catalyst by the conversion amount of olefins in the reaction process with synthesis gas under the action of rhodium catalyst in the working solution.

[0022] The present application uses the area normalization method to calculate the conversion rate and normal-isomer ratio of the working solution according to the peak area or peak area ratio of 1-hexene or other normal olefins, n-heptanal or other normal aldehydes, and isoheptanal or other isomer aldehydes, so as to obtain the catalytic activity of the working solution.

[0023] The catalytic activity of the rhodium catalyst working solution not only needs to be compared with different reaction degrees of the working solution, but also needs to be compared with the catalytic activity of the newly prepared qualified rhodium catalyst. The activity test process of the rhodium catalyst is basically the same as the above process. The test process is to weigh 0.04g of solid rhodium catalyst, 2-6g of triphenylphosphine, and dilute to 30mL with toluene or butyraldehyde, and then add 20mL of 1-hexene or other liquid normal olefins with a boiling point higher than room temperature into a 100mL high-pressure reaction kettle, immediately seal the kettle, and replace it with nitrogen for 2-5 times. Start heating, the temperature is raised to 70-80℃, the synthesis gas is introduced, the stirring is started, wherein the composition of the synthesis gas is CO:H2 with a volume ratio of 1:1, the concentration is 50%-100%, the pressure is controlled at 1-2MPa, and the stirring speed is 500rpm-1500rpm. The reaction time is 0.5-3h. After the reaction is completed, the synthesis gas, temperature control system and stirring system are turned off, the reaction kettle is cooled, and after being cooled to room temperature, the kettle is opened, the working solution after reaction is taken out, and is introduced into a gas chromatograph. The peak area or peak area ratio of 1-hexene or other normal olefins, n-heptanal or other normal aldehydes, and isoheptanal or other isomer aldehydes is calculated according to the above formula, so as to obtain the catalytic activity of the working solution.

[0024] Compared with the prior art, the present application has the following effects:

[0025] The present application simulates the reaction process of the rhodium catalyst working solution in the high-pressure reaction kettle, limits the amount of reactants, and judges the catalytic ability of the rhodium catalyst in the reaction system after a certain time. The equipment requirement is not high, it is convenient and fast, simple and effective, and the test result has high accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The gas chromatogram of the working solution after reaction of the present application. DETAILED DESCRIPTION

[0027] The content of the present application will be further described in detail below in combination with specific examples and comparative examples.

[0028] Example 1

[0029] Take rhodium concentration of 426 ppm of working solution A 18.8 mL, dilute to 30 mL with butyl aldehyde, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 3 times. Start heating, when the temperature rises to 80℃, introduce the synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 2h.

[0030] Example 2

[0031] Take rhodium concentration of 426 ppm of working solution A 18.8 mL, dilute to 30 mL with butyl aldehyde, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 3 times. Start heating, when the temperature rises to 80℃, introduce the synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 2h.

[0032] Example 3

[0033] Take rhodium concentration of 426 ppm of working solution A 18.8 mL, dilute to 30 mL with butyl aldehyde, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 3 times. Start heating, when the temperature rises to 80℃, introduce the synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 2h.

[0034] Example 4

[0035] Take rhodium concentration of 426 ppm of working solution A 18.8 mL, dilute to 30 mL with butyl aldehyde, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 2-5 times. Start heating, when the temperature rises to 80℃, introduce the synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 1h.

[0036] Example 5

[0037] Take rhodium concentration of 557 ppm of working solution B 14.4 mL, dilute with butyl aldehyde to 30 mL, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 2-5 times. Start heating, when the temperature rises to 80℃, introduce synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 1 h.

[0038] Example 6

[0039] Take rhodium concentration of 512 ppm of working solution C 15.6 mL, dilute with butyl aldehyde to 30 mL, then add to 100 mL high pressure reactor, add 20 mL 1-hexene, 4 g triphenylphosphine to the reactor, immediately seal the reactor, replace with nitrogen for 2-5 times. Start heating, when the temperature rises to 80℃, introduce synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 1 h.

[0040] Comparative Example 1

[0041] Take solid rhodium catalyst 0.04 g, triphenylphosphine 4 g, dissolve and dilute with toluene to 30 mL, add to 100 mL high pressure reactor together with 20 mL 1-hexene, immediately seal the reactor, replace with nitrogen for 3 times. Start heating, when the temperature rises to 80℃, introduce synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 2 h.

[0042] Comparative Example 2

[0043] Take solid rhodium catalyst 0.04 g, triphenylphosphine 4 g, dissolve and dilute with toluene to 30 mL, add to 100 mL high pressure reactor together with 20 mL 1-hexene, immediately seal the reactor, replace with nitrogen for 3 times. Start heating, when the temperature rises to 80℃, introduce synthetic gas with concentration of 100%, volume ratio of 1:1, control the pressure at 2 MPa, open the stirring, stirring speed is 1000 rpm, reaction time is 1 h.

[0044] Effect Example

[0045] After the above reaction, turn off the synthetic gas, temperature control system, stirring system, cool down the reactor, when it reaches room temperature, open the reactor, take out the working solution after reaction, introduce into the gas chromatograph, use area normalization method to calculate the peak area ratio of 1-hexene, n-heptanal, isoheptanal, calculate the conversion rate and normal iso ratio of working solution according to the formula, thus obtain the catalytic activity of working solution. The results of the above examples and comparative examples are shown in Table 1.

[0046] Table 1

[0047]

[0048] Although the foregoing describes the specific embodiments of the present application, it is not intended to limit the scope of the present application, and those skilled in the art should understand that various modifications or variations can be made to the technical solutions of the present application without departing from the scope of the present application, and such modifications or variations are still within the scope of the present application.

Claims

1. A method for evaluating the activity of a rhodium-containing catalyst working solution, characterized in that, Includes the following steps: (1) Weigh a certain volume of rhodium catalyst working solution, add it to the high-pressure reactor, then add triphenylphosphine, olefin and solvent, and immediately seal the reactor; (2) First, nitrogen gas is introduced into the reactor for replacement, then the temperature is raised, the stirring is turned on, the synthesis gas is introduced, the reaction time is started, after a certain reaction time, the synthesis gas is turned off, the reactor is cooled to room temperature, the working solution is taken out, and gas chromatography is introduced. The olefin conversion rate and the normal-iso ratio of the working solution are calculated using the area normalization method. In step (1), the volume ratio of the rhodium catalyst working solution to the olefin is 3:1-3; the olefin is a liquid n-olefin with a boiling point higher than room temperature; and the solvent is butyraldehyde. In step (2), the gas chromatography conditions are as follows: column type: KB-FFAP30m*0.32mm*1um, injector heater temperature: 300℃, column oven temperature: initial 50℃, hold for 4min, programmed temperature increase 15℃ / min, final temperature 230℃, hold for 15min; column flow rate: 1.2ml / min, split ratio: 30:1, detector: FID, heater: 300℃, H2: 30ml / min, Air: 400ml / min, tail purge nitrogen flow rate: 25ml / min; In step (2), the formula used in the area normalization method is: （1） （2） In the formula: —Peak area or peak area percentage of olefins; —Peak area or peak area percentage of normal aldehydes; —Peak area or peak area percentage of isomeric aldehydes.

2. The activity evaluation method according to claim 1, characterized in that, In step (1), the concentration of rhodium in the working solution of the rhodium catalyst is 100-500 ppm.

3. The activity evaluation method according to claim 1, characterized in that, In step (1), the mass ratio of triphenylphosphine to rhodium is 50:1-150:

1.

4. The activity evaluation method according to claim 1, characterized in that, In step (2), the reaction temperature is 70-80℃; the stirring speed is 500rpm-1500rpm.

5. The activity evaluation method according to claim 1 or 4, characterized in that, In step (2), the synthesis gas is composed of CO:H2 in a volume ratio of 1:1 and has a concentration of 50%-100%.

6. The activity evaluation method according to claim 5, characterized in that, In step (2), the reaction conditions are: pressure 1-2 MPa, reaction time 0.5-3 h.

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