CN109701522B - Preparation of supported ruthenium-based hydrogenation catalyst and application of supported ruthenium-based hydrogenation catalyst in catalytic hydrogenation of dimethyl terephthalate - Google Patents
Preparation of supported ruthenium-based hydrogenation catalyst and application of supported ruthenium-based hydrogenation catalyst in catalytic hydrogenation of dimethyl terephthalate Download PDFInfo
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Abstract
The invention provides a preparation method of a supported ruthenium-based hydrogenation catalyst and application of the supported ruthenium-based hydrogenation catalyst in catalytic hydrogenation of dimethyl terephthalate. The preparation method comprises the following steps: 1) preparing ruthenium tetroxide gas; 2) pretreating the porous carrier to pre-store the organic matter A in an internal pore channel of the porous carrier; 3) pouring the pretreated porous carrier into a reaction container, heating to 80-100 ℃, vacuumizing and degassing for 2-5 h, then closing vacuum, allowing ruthenium tetroxide gas to enter the reaction container to be mixed with the carrier under stirring, continuing stirring at constant temperature for 2-5 h, cooling to 0-5 ℃, closing and cooling, standing to room temperature, and taking out a catalyst precursor; 4) and (3) carrying out programmed temperature reduction on the catalyst precursor in methane/nitrogen to prepare the supported ruthenium-based hydrogenation catalyst. The invention provides the application of the catalyst in the catalytic hydrogenation reaction of dimethyl terephthalate, and the catalyst has the characteristics of small catalyst consumption, high conversion rate, good selectivity, high hydrogenation rate and good stability.
Description
(I) technical field
The invention relates to a hydrogenation catalyst, and preparation and application thereof, in particular to a preparation method of a supported ruthenium-based hydrogenation catalyst and application thereof in a dimethyl terephthalate catalytic hydrogenation reaction.
(II) technical background
The supported ruthenium-based catalyst is widely applied to the fields of ammonia synthesis, cyclohexanone preparation by benzene hydrogenation, sugar alcohol preparation by hydrogenation of glucose/xylose and the like. The noble metal ruthenium is loaded on the carrier, so that the specific surface area of the metal particles can be increased to improve the activity and the metal utilization rate of the catalyst, the interaction between the ruthenium particles and the carrier can be regulated, the crystalline phase and the electronic structure of the ruthenium metal particles can be regulated, and the requirements of different catalytic hydrogenation reactions can be met. The structural properties of the catalyst material are often closely related to the catalyst preparation process. The supported ruthenium-based catalyst is generally prepared by an impregnation method, an ion exchange method, a deposition-precipitation method, or the like. The impregnation method is the most common preparation method, and generally, the carrier is poured into a water-soluble precursor solution of ruthenium metal, ruthenium precursor ions are adsorbed on the surface and in the pore channels of the carrier, and after the impregnation and adsorption are balanced, the carrier is washed, dried, reduced and the like. The dipping method has simple and mature process, but the ruthenium metal has poor dispersibility, and the particle size and the distribution are not easy to regulate and control. The ion exchange method is to use an ion exchanger as a carrier and load ruthenium on the carrier by utilizing the exchange performance of ions, for example, Kumar and the like take ruthenium trichloride as a precursor and sodium MCM-41 as a carrier to prepare the Ru-MCM-41 catalyst. The ruthenium particles are dispersed more uniformly, but the method has limited application. The precipitation method is to immerse the carrier in the aqueous solution of the ruthenium metal precursor, fully stir until the ruthenium ions and the carrier are uniformly mixed, and uniformly deposit ruthenium on the surface of the carrier by regulating and controlling proper temperature and pH value and adding a precipitator. The method can effectively disperse ruthenium metal particles, but the utilization rate of the metal is not high.
In conclusion, the activity and selectivity of the existing ruthenium-based hydrogenation catalysts are still to be improved. Particularly, the ruthenium-based catalyst still does not make a great breakthrough in the reaction of generating 1, 4-cyclohexyl methyl phthalate by hydrogenating dimethyl terephthalate.
Disclosure of the invention
The first purpose of the invention is to provide a preparation method of a supported ruthenium-based hydrogenation catalyst, which can realize ultrahigh dispersion and high stability of metal on the surface of the catalyst, and enables ruthenium particles to be distributed on the outer surface layer of a carrier, and has the advantages of simple operation, high efficiency and economy.
The second purpose of the invention is to provide the application of the supported ruthenium-based hydrogenation catalyst in the catalytic hydrogenation reaction of dimethyl terephthalate, and the supported ruthenium-based hydrogenation catalyst has the characteristics of small catalyst dosage, high conversion rate, good selectivity, high hydrogenation rate and good stability.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the invention provides a preparation method of a supported ruthenium-based hydrogenation catalyst, which comprises the following steps:
1) preparing ruthenium tetroxide gas;
2) pretreatment of the porous carrier: soaking a porous carrier in a mixed solution containing an organic substance A for 1-2 hours, wherein the mixed solution is prepared from methanol or ethanol and the organic substance A according to the mass ratio of 0.5-5: 1, the organic substance A is an alcohol, ether or aldehyde organic compound which is dissolved in the methanol or ethanol and has a boiling point of more than 150 ℃, and then treating the organic substance A for 10-30 min at the temperature of 0-20 ℃ and the vacuum degree of-0.05 MPa to completely remove the methanol or the ethanol, so as to obtain a pretreated porous carrier; the purpose of the step is that the organic matter A is pre-stored in the inner pore canal of the porous carrier;
3) pouring the pretreated porous carrier into a reaction container, heating to 80-100 ℃, carrying out vacuum degassing for 2-5 h under the condition that the absolute pressure in the reaction container is 50-100 mm Hg, then closing the vacuum, enabling ruthenium tetroxide gas to enter the reaction container to be mixed with the carrier under stirring, controlling the flow rate of the ruthenium tetroxide gas to be adapted to the adsorption speed of the carrier so as to keep the absolute pressure in the reaction container between 50-100 mm Hg, continuing stirring at the constant temperature of 80-100 ℃ for 2-5 h, then reducing the temperature to 0-5 ℃ at the speed of 5-20 ℃/min, closing the temperature, cooling, standing to room temperature, and taking out a catalyst precursor;
4) carrying out temperature programming reduction on the catalyst precursor prepared in the step 3) in a methane/nitrogen mixed atmosphere, wherein CH is obtained4/N2CH in mixed gas4The volume content is 10-40%, and the temperature programming process is as follows: raising the temperature from-20 to-5 ℃ to 400 to 500 ℃ at a temperature raising rate of 1 to 5 ℃/min, and keeping the temperature for 1 to 5 hours to prepare the supported ruthenium-based hydrogenation catalyst.
According to the supported ruthenium-based hydrogenation catalyst, during the preparation process, the characteristic that ruthenium tetroxide is volatile is utilized, and the pre-dispersion of ruthenium on the outer surface of the carrier is realized by adopting a supporting mode that the volatile ruthenium tetroxide and a porous carrier with an internal pore channel pre-stored with an organic matter A are adsorbed and deposited; secondly, regulating the processes of deposition and crystallization on the carrier by regulating the sublimation and desublimation processes of the ruthenium tetroxide gas through temperature (firstly raising the temperature and then lowering the temperature) and vacuum degree, so as to achieve the accurate regulation and control of the size, crystalline phase and morphology of ruthenium particles; thirdly, the organic matter A prestored in the carrier pore channel plays a role in regulating and controlling the distribution of ruthenium metal in space on one hand, and can also quickly generate chemical reaction with ruthenium tetroxide to play a role in regulating and controlling the distribution of ruthenium metal on the other hand; finally, CH starting at subzero temperature4/N2The temperature programmed reduction in the atmosphere inhibits the easy agglomeration phenomenon in the crystal phase transformation process when the ruthenium oxide particles are reduced, and when the porous carrier is porous carbon, CH4Disproportionation reaction can also occur under the catalytic action of ruthenium particles to generate a graphitized carbon layer on the surface, and the strong interaction between ruthenium metal particles and the carrier is gradually reconstructed, so that the carrier (carbon material carrier) has anti-methanation performance. Under the combined action of the four factors, the catalyst with ultrahigh dispersion, high stability and an eggshell-like distribution structure of ruthenium on the surface of the carrier is formed.
Preferably, the preparation of the ruthenium tetroxide gas in step 1) of the present invention is carried out at a temperature of not higher than 100 ℃ in an anhydrous atmosphere. Specifically, ruthenium tetroxide gas is prepared by the following method:
1-a) mixing ruthenium, potassium hydroxide and potassium nitrate according to a molar ratio of 1: 2-2.5: 3-3.5, and roasting at 650 ℃ until the mixture is melted for 1 hour; then cooling to 50-80 ℃, adding a proper amount of hot water, and stirring until the solid is completely dissolved;
Ru+3KNO3+2KOH＝＝K2RuO4+3KNO2+H2O
1-b) pouring the prepared solution into a reaction container, dripping a proper amount of oxidizing solution, wherein the oxidizing solution is 15-30 wt% of hydrogen peroxide, 5-15 wt% of sodium chlorate or 3-10 wt% of perchloric acid, heating to 50-80 ℃, reacting for about 30 minutes, and slowly adding a proper amount of sulfuric acid solution, wherein golden yellow ruthenium tetroxide gas is generated;
K2RuO4+NaClO+H2SO4＝＝RuO4+K2SO4+NaCl+H2O
more preferably, the dosage of the oxidizing solution in the step 1-b) is 1-1.5: 1.
preferably, the amount of the sulfuric acid solution used in the step 1-b) is 5-10: 1.
preferably, the organic substance a in step 2) is one of ethylene glycol and its polymer, diphenyl ether, anisole, benzaldehyde, and p-carboxybenzaldehyde.
The support in step 3) of the present invention may be any porous catalyst support material. Preferably, the carrier is selected from porous carbon or alumina, wherein the porous carbon carrier can be activated carbon, mesoporous carbon, other synthetic carbon materials synthesized according to the methods reported in the literature, and the like.
Preferably, the loading amount of ruthenium in the catalyst is 0.1-5 wt%. The loading of the catalyst is controlled by the ratio of ruthenium to support added.
On the other hand, the invention provides an application of the supported ruthenium-based hydrogenation catalyst in a reaction of catalyzing dimethyl terephthalate to be hydrogenated to generate 1, 4-cyclohexyl methyl phthalate, and the application specifically comprises the following steps: putting dimethyl terephthalate, a solvent and the supported ruthenium-based hydrogenation catalyst into a high-pressure hydrogenation reaction kettle, sealing the reaction kettle, replacing air, filling hydrogen, starting stirring, and carrying out catalytic hydrogenation reaction under the conditions that the temperature is 80-180 ℃ and the hydrogen pressure is 3.0-8.0 MPa; and (3) monitoring the pH value of the hydrogenation liquid on line in real time before and during the reaction, ensuring that the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and carrying out real-time adjustment by linking an alkaline assistant to obtain the 1, 4-methyl cyclohexyl dicarboxylate after full reaction. Generally, in the reaction process, after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of reactants in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate.
Preferably, the solvent is ethyl acetate, methanol, ethanol, THF or DMF, preferably THF or ethyl acetate. The ratio of the solvent to the reactant is 100:10 to 100(ml/g), preferably 100:10 to 20 (ml/g).
Preferably, the alkaline auxiliary agent is plant alkali, preferably concentrated juice of tea leaves, barley leaves, soybean stems and the like.
Preferably, the mass ratio of the dimethyl terephthalate to the supported ruthenium-based hydrogenation catalyst is 100:1 to 5.
Preferably, the hydrogenation temperature is 100-150 ℃, and the hydrogen pressure is 4.0-6.0 MPa.
Compared with the prior art, the invention has the beneficial effects that:
1) the preparation method of the supported ruthenium-based hydrogenation catalyst utilizes A) volatility of ruthenium tetroxide, B) space-time particle distribution regulation of high boiling point alcohol, ether and aldehyde organic matters, C) temperature and vacuum degree to regulate sublimation and desublimation of ruthenium tetroxide gas and D) CH starting at subzero temperature4/N2The method of temperature programming reduction in atmosphere, anchoring of the new carbon layer and the like constructs the ultra-high dispersion and high stability of ruthenium on the surface of the carrierThe catalyst is in an eggshell-like distribution structure. And when the porous carrier is activated carbon, the carrier also has methanation resistance. The preparation method takes ruthenium metal as a starting material, and has the advantages of low cost, simple preparation process, convenient operation and high metal utilization rate.
2) The active site structure of the supported ruthenium-based hydrogenation catalyst is particularly suitable for the reaction of generating 1, 4-cyclohexyl methyl diformate by hydrogenating dimethyl terephthalate, the reaction is concentrated outside catalyst particles, the mass transfer influence is greatly reduced, and the supported ruthenium-based hydrogenation catalyst has the advantages of high activity, high selectivity, high hydrogenation rate, high stability, long service life and low unit consumption cost.
3) The catalytic hydrogenation process of the invention uses plant alkali, and is safe and nontoxic.
(IV) description of the drawings
FIG. 1 is a schematic diagram of a catalyst preparation apparatus used in the present invention, wherein 1-valve, 2-air tube, 3-funnel, 4-fractionation tube, 5-valve, 6-funnel, 7-valve.
Fig. 2 is a TEM image of the catalyst prepared in example 8.
(V) detailed description of the preferred embodiments
The technical solution of the present invention is illustrated by the following specific examples, but the scope of the present invention is not limited thereto:
examples catalyst preparation was carried out in an apparatus as shown in fig. 1, comprising two three-necked flasks (a, B) and a fractionating tube.
One opening of the three-mouth flask A is connected with an air pipe 2 with a valve 1, one end of the air pipe is opened in the air steel cylinder, and the other end of the air pipe is inserted below the liquid level; the second opening of the three-mouth flask A is connected with a funnel 3 with a valve and is used for dropwise adding reaction liquid such as oxidizing solution, sulfuric acid and the like; the third port of the three-port flask A is connected with a fractionating pipe 4.
One port of the three-port flask B is connected with the other opening of the fractionating pipe 4 through a pipe with a valve 5; the remaining two ports of the three-necked flask B, one connected to a vacuum device 7 and one as a carrier addition port 6.
Example 1
Preparing ruthenium-based hydrogenation catalyst with 5 percent of ruthenium loading. The specific process is as follows:
1) ruthenium, potassium hydroxide and potassium nitrate are mixed according to a molar ratio of 1: 2.1: 3.2, and roasting at 650 ℃ until the mixture is molten for 1 hour. Then cooling to 80 ℃, adding a proper amount of hot water, and stirring until the solid is completely dissolved.
2) The solution prepared above was poured into a three-necked flask a, and a 15 wt% sodium hypochlorite solution was dropped through a funnel, the amount of the substance of sodium hypochlorite being 1.5 times as much as ruthenium. Then, the temperature is raised to 80 ℃, the mixture is stirred, and concentrated sulfuric acid solution with the amount of 5 times that of ruthenium substances is slowly added from a funnel after the reaction is carried out for about 30 minutes, and golden yellow ruthenium tetroxide gas is generated.
3) The activated carbon (3sw, particle size:250-300mesh, N) was weighed to give a 5% loading2-BET:980m2g-1,ash content:<3 percent) of the raw materials are soaked in a mixed solution of ethylene glycol and ethanol with the mass ratio of 5:1 for 1h, and then dried for 30min at the temperature of 20 ℃ and the vacuum degree of-0.05 MPa. Then, the activated carbon was poured into a three-necked flask B, and the vacuum apparatus was turned on, and the absolute pressure was set at 100mm Hg while the temperature was raised to 100 ℃ and degassed for 5 hours. And (3) closing the vacuum, opening the magnetic stirring, and slowly opening a valve to allow the ruthenium tetroxide gas to enter the three-neck flask B after being separated by the fractionating tube 3 and to be mixed with the carrier. The speed of ruthenium tetroxide gas is controlled by controlling the speed of sulfuric acid dropping in the step 2), so that the ruthenium tetroxide gas is adapted to the adsorption speed of the carrier, and the absolute pressure in the container is maintained at 100mm Hg. Stirring is continued for 5h at constant temperature of 100 ℃. Then the temperature was decreased to 5 ℃ at a rate of 20 ℃/min. Closing the temperature, cooling, standing to room temperature, and taking out for later use.
4) Sample prepared in step 3) is in CH440% by volume of CH4/N2In the mixed atmosphere, the temperature is raised from minus 10 ℃ to 500 ℃ at the heating rate of 5 ℃/min, and the temperature is kept for 5 h. And obtaining the supported ruthenium-based hydrogenation catalyst.
Examples 2 to 11 are examples of catalysts prepared according to the preparation process of example 1 using different preparation conditions, as detailed in table 1. Among these, the synthetic carbon preparation method of example 8 is from Liu, J.et.extension Soft stock method to the preparation of monodisperse carbon-formaldehyde resin polymer and carbon spheres, Angewandte Chemie 50, 5947-; alumina, 200-600 meshes, specific surface area 600, pore volume 0.52, produced by Wenzhou refined alumina Co., Ltd; mesoporous carbon of-600 m2(iv)/g, Jiangsu Xiancheng nanometer materials science and technology limited.
Comparative example 1
The preparation method of the conventional carbon-supported ruthenium catalyst comprises the following steps: transferring 10mL of ruthenium trichloride solution with the concentration of 0.05g/mL into 50mL of deionized water, and adjusting the pH value of the ruthenium trichloride solution to be 0.8 by hydrochloric acid; then, 10g of the activated carbon which is dried and dehydrated in vacuum and is prepared in the same way as the activated carbon in the embodiment 2 is soaked in ruthenium liquid, fully stirred and soaked for 6 hours at the temperature of 80 ℃, and the pH value is adjusted to 8-10 by using 5 wt% of sodium hydroxide solution; after 1 hour, 2.5mL of hydrazine hydrate was added dropwise and reduced at 35 ℃ for 2 hours. Then cooling to room temperature, filtering the reaction system, washing the filter cake to be neutral by using deionized water, and drying and dehydrating for 4 hours at 110 ℃ to obtain the supported ruthenium catalyst with the load of 5 percent.
Comparative example 2
The carrier was not pretreated with a glycol/ethanol mixture, and the rest of the procedure was the same as in example 1.
Comparative example 3
No sulfuric acid is used in step 2). The rest of the procedure was the same as in example 6.
Comparative example 4
The absolute pressure in the flask in step 3) is above 100mm Hg. The rest of the procedure was the same as in example 1.
Comparative example 5
No procedure cooling process is performed in step 3). The rest of the procedure was the same as in example 1.
Comparative example 6
CH is not used in step 3)4By reduction, but with H2And (4) reducing. The rest of the procedure was the same as in example 1.
Examples 12 to 20 are examples in which the catalyst prepared by the above-mentioned preparation method is applied to a reaction of hydrogenating dimethyl terephthalate to produce methyl 1, 4-cyclohexyldicarboxylate.
The preparation method using plant alkaloid in the following examples is: respectively mixing tea leaves, barley young leaves and soybean stems with water according to a mass ratio of 1: 1, juicing by using a juicer, carrying out filter pressing, concentrating the obtained filtrate, concentrating at 50 ℃ under vacuum of-0.06 to-0.1 MPa until no water is evaporated out to obtain concentrated juice, and storing in a light-shielding inert atmosphere.
Example 12
100g of dimethyl terephthalate, 200ml of THF and 5g of the ruthenium-based hydrogenation catalyst of example 1 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at 100 ℃ and a hydrogen pressure of 4.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of the tea leaves is linked to adjust in real time. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3h, the conversion rate is 100 percent, and the selectivity is 99.4 percent.
Example 13
100g of dimethyl terephthalate, 100ml of THF and 1g of the ruthenium-based hydrogenation catalyst of example 6 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at 120 ℃ under a hydrogen pressure of 6.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 4h, the conversion rate is 100 percent, and the selectivity is 99.4 percent.
Example 14
100g of dimethyl terephthalate, 1000ml of THF and 3g of the ruthenium-based hydrogenation catalyst of example 3 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at 120 ℃ and a hydrogen pressure of 4.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the hydrogenation liquid is adjusted in real time by linking the concentrated juice of the soybean stems. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3h, the conversion rate is 100 percent, and the selectivity is 99.2 percent.
Example 15
100g of dimethyl terephthalate, 500ml of ethyl acetate and 1g of the ruthenium-based hydrogenation catalyst of example 7 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at a temperature of 150 ℃ and a hydrogen pressure of 5.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 2.5h, the conversion rate is 100 percent, and the selectivity is 99.2 percent.
Example 16
100g of dimethyl terephthalate, 500ml of ethyl acetate and 2g of the ruthenium-based hydrogenation catalyst of example 8 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at 130 ℃ and a hydrogen pressure of 4.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3h, the conversion rate is 100 percent, and the selectivity is 99.3 percent.
Example 17
100g of dimethyl terephthalate, 500ml of ethyl acetate and 1g of the ruthenium-based hydrogenation catalyst of example 9 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at 100 ℃ and a hydrogen pressure of 4.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3.5h, the conversion rate is 100 percent, and the selectivity is 99.2 percent.
Example 18
100g of dimethyl terephthalate, 500ml of ethyl acetate and 5g of the ruthenium-based hydrogenation catalyst of example 3 were put into a high-pressure hydrogenation reactor, the reactor was closed, hydrogen was introduced after air replacement to start stirring, and catalytic hydrogenation was carried out at a temperature of 110 ℃ and a hydrogen pressure of 4.5 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3.5h, the conversion rate is 100 percent, and the selectivity is 99.1 percent.
Example 19
100g of dimethyl terephthalate, 500ml of ethyl acetate and 3g of the ruthenium-based hydrogenation catalyst of example 6 were placed in a high-pressure hydrogenation reactor, the reactor was closed, air was replaced and hydrogen was introduced to start stirring, and catalytic hydrogenation was carried out at a temperature of 140 ℃ and a hydrogen pressure of 5.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 3h, the conversion rate is 100 percent, and the selectivity is 99.0 percent.
Example 20
100g of dimethyl terephthalate, 500ml of ethyl acetate and 4g of the ruthenium-based hydrogenation catalyst of example 6 were put into a high-pressure hydrogenation reactor, the reactor was closed, hydrogen was introduced after air replacement to start stirring, and catalytic hydrogenation was carried out at a temperature of 150 ℃ and a hydrogen pressure of 4.0 MPa. Before and during the reaction, the pH value of the hydrogenation liquid is monitored on line in real time, the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and the concentrated juice of barley leaves is linked for real-time adjustment. And after hydrogen is not absorbed, sampling and analyzing on line, and stopping the reaction after the content of the reactant in the hydrogenation liquid is 0 to obtain the 1, 4-cyclohexyl methyl dicarboxylate. The reaction time is 2.5h, the conversion rate is 100 percent, and the selectivity is 99.4 percent.
Comparative example 7
The pH of the hydrogenated liquid was adjusted without using an alkaline substance, and the rest was the same as in example 14. The reaction time was 270 minutes, the conversion 98% and the selectivity 92.2%.
Comparative example 8
The pH of the hydrogenation solution was adjusted using sodium hydroxide solution as in example 14. The reaction time was 80 minutes, the conversion was 100% and the selectivity was 94.3%.
Comparative example 9
The pH of the hydrogenation solution was adjusted to 7.1 using a phytoalkan tea solution as in example 14. The reaction time was 100 minutes, the conversion was 96%, and the selectivity was 96.2%.
TABLE 2 results of catalytic performances of comparative examples 1-6 under the reaction conditions of example 14
| Examples | Catalyst and process for preparing same | Reaction time h | Conversion rate% | Selectivity% |
| 21 | Comparative example 1 | 5.5 | 92 | 92.1 |
| 22 | Comparative example 2 | 5.8 | 93 | 91.1 |
| 23 | Comparative example 3 | 5.5 | 94 | 92.3 |
| 24 | Comparative example 4 | 6.5 | 94 | 92.1 |
| 25 | Comparative example 5 | 6.0 | 91 | 92.2 |
| 26 | Comparative example 6 | 6.8 | 93 | 92.6 |
Example 27
Comparative example 6 after the catalyst was used mechanically for 10 times under the reaction conditions of example 14, the carrier activated carbon skeleton collapsed, and there was a significant loss of quality due to methanation. The catalytic performance is obviously reduced, the conversion rate is only 10 percent and the selectivity is 83.4 percent when the reaction lasts for 240 min.
Example 28
The results of the catalyst application experiment of example 14 are shown in table 3.
TABLE 3 results of the experiment for applying the catalyst of example 14
Examples 29 to 38
The effects of the catalysts prepared in examples 1-2 and 4-11 on the reaction conditions of example 14 are shown in Table 4:
TABLE 4 reaction Effect of the catalysts prepared in examples 1-11 under the application conditions of example 14
Claims (9)
1. A preparation method of a supported ruthenium-based hydrogenation catalyst comprises the following steps:
1) preparing ruthenium tetroxide gas;
2) pretreatment of the porous carrier: soaking a porous carrier in a mixed solution containing an organic substance A for 1-2 hours, wherein the mixed solution is prepared from methanol or ethanol and the organic substance A according to the mass ratio of 0.5-5: 1, the organic substance A is an alcohol, ether or aldehyde organic compound which is dissolved in the methanol or ethanol and has a boiling point of more than 150 ℃, and then treating the organic substance A for 10-30 min at the temperature of 0-20 ℃ and the vacuum degree of-0.05 MPa to completely remove the methanol or the ethanol, so as to obtain a pretreated porous carrier; the carrier is selected from porous carbon or alumina;
3) pouring the pretreated porous carrier into a reaction container, heating to 80-100 ℃, carrying out vacuum degassing for 2-5 h under the condition that the absolute pressure in the reaction container is 50-100 mm Hg, then closing the vacuum, enabling ruthenium tetroxide gas to enter the reaction container to be mixed with the carrier under stirring, controlling the flow rate of the ruthenium tetroxide gas to be adapted to the adsorption speed of the carrier so as to keep the absolute pressure in the reaction container between 50-100 mm Hg, continuing stirring at the constant temperature of 80-100 ℃ for 2-5 h, then reducing the temperature to 0-5 ℃ at the speed of 5-20 ℃/min, closing the temperature, cooling, standing to room temperature, and taking out a catalyst precursor;
carrying out temperature programming reduction on the catalyst precursor prepared in the step 3) in a methane/nitrogen mixed atmosphere, wherein CH is obtained4/N2CH in mixed gas4The volume content is 10-40%, and the temperature programming process is as follows: heating from-20 to-5 ℃ to 400 to 500 ℃ at a heating rate of 1 to 5 ℃/min, and keeping the temperature for 1 to 5 hours to prepare the supported ruthenium-based hydrogenation catalyst.
2. The method of claim 1, wherein: the organic matter A in the step 2) is one of ethylene glycol and a polymer thereof, diphenyl ether, anisole, benzaldehyde and p-carboxybenzaldehyde.
3. The method of claim 1, wherein: the loading amount of ruthenium in the catalyst is 0.1-5 wt%.
4. The application of the supported ruthenium-based hydrogenation catalyst prepared by the preparation method according to claim 1 in catalyzing the reaction of hydrogenating dimethyl terephthalate to generate methyl 1, 4-cyclohexyldicarboxylate comprises the following specific applications: putting dimethyl terephthalate, a solvent and the supported ruthenium-based hydrogenation catalyst into a high-pressure hydrogenation reaction kettle, sealing the reaction kettle, replacing air, filling hydrogen, starting stirring, and carrying out catalytic hydrogenation reaction under the conditions that the temperature is 80-180 ℃ and the hydrogen pressure is 3.0-8.0 MPa; and (3) monitoring the pH value of the hydrogenation liquid on line in real time before and during the reaction, ensuring that the pH value of the hydrogenation liquid in the kettle is kept at 7.5-8.0, and carrying out real-time adjustment by linking an alkaline assistant to obtain the 1, 4-methyl cyclohexyl dicarboxylate after full reaction.
5. The use of claim 4, wherein: the solvent is ethyl acetate, methanol, ethanol, THF or DMF, and the ratio of the solvent to the reactant is 100ml: 10-100 g.
6. The use of claim 4, wherein: the alkaline auxiliary agent is plant alkali.
7. The use of claim 6, wherein: the plant alkaloid is concentrated juice of tea, barley leaves or soybean stems.
8. The use of claim 4, wherein: the mass ratio of the dimethyl terephthalate to the supported ruthenium-based hydrogenation catalyst is 100:1 to 5.
9. The use of claim 4, wherein: the hydrogenation temperature is 100-150 ℃, and the hydrogen pressure is 4.0-6.0 MPa.
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