Background
Polyether Amine (PEA), also known as Amine-Terminated Polyethers (Amine-Terminated Polyethers), is a compound with a polyoxyalkylene structure as a main chain and Amine groups at the ends as active functional groups. As the amido hydrogen at the tail end of the polyether amine has stronger reaction activity compared with the hydroxyl hydrogen at the tail end of the polyether amine, the polyether amine can react with various compounds, and the application range of the polyether amine in the industrial field is greatly widened. The polyether amines can be further classified into primary amine polyether amines and secondary amine polyether amines according to the number of substituted hydrogen atoms in the amine group, and the commercially common primary amine polyether amines include polyethylene oxide diamine, polypropylene oxide diamine, polyethylene oxide/polypropylene oxide diamine, and the like. By selecting different polyoxyalkyl structures, the properties of reactivity, toughness, viscosity, hydrophilicity and the like after amination are changed, and the current commercial polyether amine comprises a series of products with single function, double function and triple function and the molecular weight of 230 to 5000. The compounds are widely applied to the fields of epoxy resin curing agents, polyurethane (polyurea) industry, gasoline detergent dispersants and the like due to the excellent performance of the compounds. At present, the largest producers of the polyetheramines internationally are the Huntsman company in the United states and the BASF company in Germany, the Huntsman company and the BASF company occupy more than 90% of market share, the research and development of the polyetheramines in China is started later, and the products have larger gaps in terms of specifications, quantity and quality compared with the products abroad.
The main methods for synthesizing polyether amine include catalytic reduction amination, leaving group method, hydrolysis method and nitro end capping method, and currently, the catalytic reduction amination method is mainly used industrially, and the method is characterized in that the mixture of polyether, ammonia and hydrogen is directly subjected to catalytic reduction amination in the presence of a catalyst at a certain temperature and pressure to produce polyether amine. For polyethers of different structural distributions and molecular weights, the catalytic reductive amination method can be further divided into a batch autoclave reaction and a continuous fixed bed reaction. The continuous reaction has become a mainstream industrial process route due to the advanced process route, easy control, simple operation, high production efficiency, short production period and high product quality.
Patent CN104119239A discloses a method for producing small molecular weight polyetheramine by continuous method, which adopts a continuous method fixed bed process form, adopts a form of connecting 2-6 reactors in series, and reduces the influence of generated water on the catalyst and improves the conversion rate of the reaction by filling different raney metal catalysts and supported metal catalysts or catalysts with different nickel-cobalt contents. The temperature of each reactor is 180 ℃ and 240 ℃, the pressure is 11.5-19.5MPa, the molar ratio of hydroxyl contained in polyether to liquid ammonia is 1:20-80, and the molar ratio of hydroxyl contained in polyether to hydrogen is 1: 0.4-5.
The patent CN104693434A discloses a method for continuously synthesizing polyether amine by a fixed bed, which is characterized in that polyether polyol and liquid ammonia are uniformly mixed by spraying and then mixed with hydrogen, then the mixture is subjected to hydroamination reaction in a fixed bed reactor containing an activated framework nickel catalyst loaded with nickel, copper and lanthanum under the reaction conditions of the temperature of 130-280 ℃ and the pressure of 3.0-15.0MPa, the continuous discharge is carried out by gas-liquid separation, and the product is subjected to vacuum rotary evaporation, dehydration and deamination to obtain polyether amine.
The most key in the process of preparing the polyether amine is the selection and preparation of a catalyst, the most commonly used catalyst in the industry at present is a supported metal catalyst, most of which takes alumina as a carrier and takes heavy metals such as copper, chromium and nickel as main active ingredients of the catalyst.
Patent CN106957420A discloses a preparation method of an alumina supported catalyst, wherein the catalyst comprises 5-15% of nickel, 5-10% of cobalt, 2-10% of rhenium, 1-5% of molybdenum and 1-5% of rhenium, and the balance of carrier gamma-Al2O3。
Patent CN102336903A discloses a preparation method of raney nickel/aluminum catalyst, wherein the nickel content in the catalyst is 85-95%, and the aluminum content is 5-15%.
The above catalyst using alumina as a carrier generally has the problem of deactivation in the amination process, wherein water generated in the hydroamination reaction is a key factor causing the deactivation of the catalyst, and the deactivation rate is proportional to the amount of water generated, the root cause of which is that the carrier is subject to partial or complete crystal phase transition, i.e. rehydration phenomenon, when encountering water during the amination process, thereby causing the reduction or deactivation of the catalyst activity, low durability and reduced service life.
In order to solve the problem of catalyst deactivation, in patent CN107876098, activated carbon is used to replace alumina, and organic amine is used to modify the surface of activated carbon, so as to generate amide nitrogen groups, enhance the non-polarity of the surface of the carrier, and effectively solve the problem of water deactivation of the alumina carrier, but the catalyst still has the problems of high metal loading, non-uniform dispersion and metal loss, and the cost for preparing the catalyst is also high.
The above prior art catalytic reductive amination processes all suffer from the following drawbacks: the preparation of the catalyst is quite complicated whether a batch method or a continuous method is adopted, and the catalyst is easy to inactivate and break and has short service life. The production conditions are very strict, the high-temperature and high-pressure conditions of the amination reaction have higher requirements on equipment, the product selectivity is reduced, the conversion rate is reduced, and for small-molecule polyether, the conditions are particularly serious, so that the appearance color and luster are influenced, and the performance of downstream products is also influenced.
The present application was made based on this.
Disclosure of Invention
The invention aims to provide a supported catalyst for synthesizing polyetheramine, which overcomes the defect of poor hydration resistance of the existing hydroamination catalyst and has high activity and good selectivity.
In order to achieve one aspect of the above purpose, the following technical solutions are adopted in the present application:
a supported catalyst comprises an activated carbon carrier and a metal loaded on the carrier, wherein the loaded metal is platinum group metal palladium with the highest hydrogenation and dehydrogenation activity, the active component of the catalyst is metal palladium, and the content of the palladium is 0.4-0.6 wt% of the catalyst.
The content of the palladium is 0.45-0.55 wt%.
The specific surface area of the activated carbon is 1000-1300m2(ii)/g, average pore diameter of 200 and 300 nm; the activated carbon carrier is selected from wood charcoal and coconut shellOne of charcoal and coal-based charcoal.
A method of preparing a supported catalyst, the method comprising:
(1) pretreating the activated carbon carrier: performing acid leaching treatment on the selected coconut shell carbon in a 10-30% nitric acid solution, filtering, washing and drying, then roasting in an inert atmosphere, cooling to obtain an acid-treated carrier, wherein the roasting temperature is 200-400 ℃, and the roasting time is 3-5 hours, so as to obtain activated carbon;
(2) impregnation and adsorption of metal salt solutions: according to the content composition of the catalyst, immersing the activated carbon carrier prepared in the step (1) into a hydrochloric acid solution of palladium chloride, adding a sodium hydroxide solution for aging after the adsorption reaches a balance, and neutralizing with hydrochloric acid to convert palladium chloride into palladium hydroxide to be deposited on the inner hole and the surface of the carrier; then drying, and finally roasting in a muffle furnace for 2-4h at the temperature of 200-300 ℃ to obtain the palladium hydroxide loaded active carbon carrier;
(3) and (3) reduction of the catalyst: immersing the activated carbon carrier obtained in the step (2) into HCHO solution for reduction at the temperature of 90 ℃, and then injecting hydrogen for reduction when the temperature is reduced to 30-50 ℃; then filtering, washing and drying are carried out to obtain the 0.5 percent palladium-carbon catalyst.
The method for synthesizing polyether amine by using polyether polyol to carry out hydroamination reaction comprises the following specific steps: adopts a continuous fixed bed process, and the space velocity of polyether polyol is 0.2h-1-2.0h-1Under the condition, introducing ammonia with the molar weight of 5-20 times and hydrogen with the molar weight of 0.5-10 times of that of polyether polyol, and carrying out hydroamination reaction under the action of a supported catalyst, wherein the reaction temperature is 160-200 ℃ and the reaction pressure is 6-10 MPa.
The polyether polyol contains one of EO or PO or EO/PO skeleton and has an average molecular weight of 200-.
The catalyst with reduced activity needs to be recovered after multiple hydroammonation reactions, and is firstly incinerated and concentrated to remove carbon and organic matters, so that the palladium slag is prepared.
The preparation method of the palladium slag comprises the following steps: burning the waste catalyst in a muffle furnace for 4-6h, controlling the temperature at 400 ℃ for 300-.
Weighing the palladium slag, adding concentrated hydrochloric acid 9 times and concentrated nitric acid 3 times of the weight of the palladium slag into a flask, and heating and reacting in a water bath at 70-80 ℃ to completely dissolve palladium to obtain a palladium solution.
Slowly adding ammonia water dropwise into the solution while stirring, stopping adding when pH reaches 8.5-9, heating in 70-75 deg.C water bath, stirring for 30min, standing, and filtering; then dropwise adding an ammonium chloride solution while stirring, stopping dropwise adding when the pH value reaches 1-2, standing, filtering, washing the precipitate for multiple times by deionized water to obtain yellow crystals, drying the obtained yellow crystals, and roasting and deaminating the yellow crystals at the temperature of 600 ℃ in a muffle furnace to obtain powdery palladium chloride.
Compared with the prior art, the invention has the following advantages:
(1) the activated carbon is used as a carrier instead of alumina, so that the problem that the alumina carrier partially or completely changes the crystal phase when meeting water in the amination process, namely, the rehydration phenomenon is avoided, and the catalytic activity and the service life of the catalyst are improved.
(2) Research finds that the catalyst is applied to the reaction of preparing polyether amine by polyether polyol, particularly the reaction of preparing polyether amine with small molecular weight (such as D230/T403 and the like), and the excellent activity is shown, and the prepared polyether amine not only has high conversion rate and high primary amine content, but also has good color and luster and high product quality.
(3) Compared with the traditional Raney nickel catalyst, the palladium-carbon catalyst has the advantages of simple preparation process, lower cost, difficult poisoning, mild catalytic reaction conditions, easy regeneration, reutilization and resource saving.
Detailed Description
The present invention will be further described with reference to specific examples so that those skilled in the art can better understand the present invention and can practice the present invention, but the examples are not intended to limit the present invention.
In the following examples, the hydroxyl number was measured by the following method: the molecular weight was calculated by referring to GB/T12008.3-2009.
Method for determining total amine number: titrating the product by adopting 0.5mol/L hydrochloric acid solution, and calculating the total amine value of the product through the volume of the consumed hydrochloric acid.
Amination conversion ═ total amine value/hydroxyl value × 100%
Method for determining secondary/tertiary amine value: and mixing and stirring the product and salicylaldehyde with equal mass for 2 hours, titrating the product by adopting 0.5mol/L hydrochloric acid solution, and calculating the sum of secondary amine and tertiary amine values of the product according to the volume of consumed hydrochloric acid.
Primary amine selectivity ═ (total amine number-secondary/tertiary amine number)/total amine number × 100%
In the following examples, the chemicals used are of analytical purity and the amounts referred to are mass amounts unless otherwise specified.
Example 1: preparation and application of 0.4% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of coconut shell charcoal (4-8 meshes, specific surface area 1000 m)2Per g, average pore diameter of 200nm) is treated in 30 percent dilute nitric acid solution for 3 hours, filtered and washed to be neutral, baked at 200 ℃ for 3 hours in argon atmosphere and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.55g of palladium chloride for 8 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 3 hours at 300 ℃ to obtain the activated carbon carrier loaded with palladium hydroxide. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 10 hours when the temperature is reduced to 30 ℃. Then filtering, washing and drying are carried out to obtain the 0.4 percent palladium carbon catalyst.
Evaluation of catalyst: taking the preparation of polyether amine D230 by hydrogenating and aminating polyether polyol PPG-230 (with a bifunctional group and a molecular weight of 230) to prepare polyether amine D230 as an example, a continuous method fixed bed process is adopted for evaluation, wherein before reaction, a catalyst is placed into a reactor, hydrogen with the molar weight 8 times of PPG-230 is introduced, the temperature is increased to 200 ℃, the pressure is increased to 10MPa, after a system is stabilized, PPG-230 and liquid ammonia with the molar weight 8 times are pumped into the reactor by a pump, and the airspeed of PPG-230 is 2.0h-1After a certain period of reaction time, the reaction mixture is filtered. Vacuum-pumping and distilling to obtain polyetherAmine products. By chemical analysis, the reaction conversion rate is 90%, and the primary amine selectivity is 92%.
Example 2: preparation and application of 0.45% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of coconut shell charcoal (4-8 meshes, specific surface area 1100 m)2Per g, average pore diameter of 250nm) is treated in 30 percent dilute nitric acid solution for 4 hours, filtered and washed to be neutral, baked at 250 ℃ for 4 hours in argon atmosphere, and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.62g of palladium chloride for 9 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 4 hours at 350 ℃, so as to obtain the activated carbon carrier loaded with palladium hydroxide. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 13h when the temperature is reduced to 40 ℃. Then filtering, washing and drying are carried out to obtain the 0.45 percent palladium carbon catalyst.
Evaluation of catalyst: taking the preparation of polyether amine D230 by hydrogenating and aminating polyether polyol PPG-230 (with a bifunctional group and a molecular weight of 230) to prepare polyether amine D230 as an example, a continuous method fixed bed process is adopted for evaluation, wherein before reaction, a catalyst is placed into a reactor, hydrogen with the molar weight 8 times of PPG-230 is introduced, the temperature is increased to 200 ℃, the pressure is increased to 10MPa, after a system is stabilized, PPG-230 and liquid ammonia with the molar weight 8 times are pumped into the reactor by a pump, and the airspeed of PPG-230 is 2.0h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 92% and the primary amine selectivity is 93%.
Example 3: preparation and application of 0.5% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of coconut shell charcoal (4-8 meshes, specific surface area 1200 m)2Per g, average pore diameter of 300nm) is treated in 30 percent dilute nitric acid solution for 4.5 hours, filtered and washed to be neutral, baked at 300 ℃ for 5 hours in argon atmosphere, and naturally cooled. According to the content composition of the catalyst, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.71g of palladium chloride for 10 hours by adopting an immersion precipitation method until the adsorption reaches the balanceAnd then adding a sodium hydroxide solution for aging, neutralizing with hydrochloric acid, drying, and roasting at 400 ℃ for 5 hours to obtain the palladium hydroxide-loaded activated carbon carrier. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 18h when the temperature is reduced to 50 ℃. Then filtering, washing and drying are carried out to obtain the 0.5 percent palladium carbon catalyst.
Evaluation of catalyst: taking the preparation of polyether amine D230 by hydrogenating and aminating polyether polyol PPG-230 (with a bifunctional group and a molecular weight of 230) to prepare polyether amine D230 as an example, a continuous method fixed bed process is adopted for evaluation, wherein before reaction, a catalyst is placed into a reactor, hydrogen with the molar weight 8 times of PPG-230 is introduced, the temperature is increased to 200 ℃, the pressure is increased to 10MPa, after a system is stabilized, PPG-230 and liquid ammonia with the molar weight 8 times are pumped into the reactor by a pump, and the airspeed of PPG-230 is 2.0h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion was 93% and the primary amine selectivity was 95%.
Example 4: preparation and application of 0.55% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of coconut shell charcoal (4-8 meshes, specific surface area 1300 m)2Per g, average pore diameter of 250nm) is treated in 30 percent dilute nitric acid solution for 5 hours, filtered and washed to be neutral, baked at 350 ℃ for 5 hours in argon atmosphere and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.76g of palladium chloride for 11 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 6 hours at 500 ℃ to obtain the activated carbon carrier loaded with palladium hydroxide. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 20 hours when the temperature is reduced to 40 ℃. Then filtering, washing and drying are carried out to obtain the 0.55 percent palladium-carbon catalyst.
Evaluation of catalyst: taking the polyether glycol PPG-230 (difunctional group with molecular weight of 230) to prepare the polyether amine D230 by hydroamination as an example, the evaluation is carried out by adopting a continuous method fixed bed process, namely the catalyst is firstly added before the reactionPutting the reagent into a reactor, introducing hydrogen with the molar weight 8 times of PPG-230, raising the temperature to 200 ℃, raising the pressure to 10MPa, and pumping PPG-230 and liquid ammonia with the molar weight 8 times into the reactor after a system is stabilized, wherein the space velocity of PPG-230 is 2.0h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 94% and the primary amine selectivity is 97%.
Example 5: preparation and application of 0.6% palladium-carbon catalyst
Preparing a catalyst: 50g of coal charcoal (4-8 meshes, specific surface area 1300 m) is weighed2Per g, average pore diameter of 250nm) is treated in 30 percent dilute nitric acid solution for 5 hours, filtered and washed to be neutral, baked at 350 ℃ for 5 hours in argon atmosphere and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.84g of palladium chloride for 12 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 6 hours at 500 ℃ to obtain the activated carbon carrier loaded with palladium hydroxide. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 20 hours when the temperature is reduced to 40 ℃. Then filtering, washing and drying are carried out to obtain the 0.6 percent palladium carbon catalyst.
Evaluation of catalyst: taking trimethylolpropane polyether (trifunctional group, molecular weight 424) hydroamination to prepare polyetheramine T-403 as an example, adopting a continuous fixed bed process for evaluation, namely putting a catalyst into a reactor before reaction, introducing hydrogen with 10 times of molar weight of trimethylolpropane polyether, raising the temperature to 200 ℃, raising the pressure to 10MPa, and pumping the trimethylolpropane polyether and liquid ammonia with 15 times of molar weight into the reactor through a pump after a system is stable, wherein the airspeed of the trimethylolpropane polyether is 1.5h-1After a certain period of reaction time, the reaction mixture is filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 95% and the primary amine selectivity is 97%.
Example 6: preparation and application of 0.6% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of apricot hull charcoal(4-8 mesh, specific surface area 1200 m)2Per g, average pore diameter 300nm) is treated in 30 percent dilute nitric acid solution for 4.5 hours, filtered and washed to be neutral, baked at 350 ℃ for 4 hours in argon atmosphere, and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.84g of palladium chloride for 12 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 5 hours at 400 ℃ to obtain the activated carbon carrier loaded with palladium hydroxide. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 15h when the temperature is reduced to 50 ℃. Then filtering, washing and drying are carried out to obtain the 0.6 percent palladium carbon catalyst.
Evaluation of catalyst: taking glycol polyether (difunctional group with molecular weight of 600) hydroamination to prepare polyether amine ED-600 as an example, a continuous method fixed bed process is adopted for evaluation, namely, before reaction, a catalyst is placed into a reactor, hydrogen with the molar weight of 8 times of that of the glycol polyether is introduced, the temperature is increased to 190 ℃, the pressure is increased to 9MPa, after a system is stabilized, the glycol polyether and liquid ammonia with the molar weight of 8 times are pumped into the reactor by a pump, and the airspeed of the glycol polyether is 2h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 94% and the primary amine selectivity is 96%.
Example 7: preparation and application of 0.6% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of wood charcoal (4-8 meshes, specific surface area 1100 m)2Per g, average pore diameter of 200nm) is treated in 30 percent dilute nitric acid solution for 4.5 hours, filtered and washed to be neutral, baked at 350 ℃ for 5 hours in argon atmosphere and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed in hydrochloric acid solution containing 0.84g of palladium chloride for 12 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 4.5 hours at 300 ℃ to obtain the activated carbon carrier loaded with palladium hydroxide. Then immersing the palladium hydroxide-loaded activated carbon carrier obtained in the step into the solution at the temperature of 90 DEG CReducing in HCHO solution, cooling to 50 deg.C, injecting hydrogen gas, and reducing for 10 h. Then filtering, washing and drying are carried out to obtain the 0.6 percent palladium carbon catalyst.
Evaluation of catalyst: taking the preparation of polyether amine M2070 by hydroamination of methanol polyether (monofunctional group, molecular weight is 2070) as an example, a continuous fixed bed process is adopted for evaluation, namely, before the reaction, a catalyst is placed in a reactor, hydrogen with 10 times of molar weight of methanol polyether is introduced, the temperature is increased to 170 ℃, the pressure is increased to 7MPa, after a system is stabilized, ethylene glycol polyether and liquid ammonia with 10 times of molar weight are pumped into the reactor by a pump, and the airspeed of the methanol polyether is 1h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 92% and the primary amine selectivity is 94%.
Example 8: preparation and application of 0.6% palladium-carbon catalyst
Preparing a catalyst: weighing 50g of coconut shell charcoal (4-8 meshes, specific surface area 1200 m)2Per g, average pore diameter 300nm) is treated in 30 percent dilute nitric acid solution for 4.5 hours, filtered and washed to be neutral, baked at 350 ℃ for 4 hours in argon atmosphere, and naturally cooled. According to the content composition of the catalyst, an impregnation precipitation method is adopted, the activated carbon carrier is immersed into hydrochloric acid solution containing 0.84g of palladium chloride for 12 hours, after adsorption is balanced, sodium hydroxide solution is added for aging, then hydrochloric acid is used for neutralization, then drying is carried out, and roasting is carried out for 5 hours at 400 ℃, so as to obtain the palladium hydroxide-loaded activated carbon carrier. And then, immersing the obtained palladium hydroxide-loaded activated carbon carrier into an HCHO solution for reduction at the temperature of 90 ℃, and injecting hydrogen for reduction for 15h when the temperature is reduced to 50 ℃. Then filtering, washing and drying are carried out to obtain the 0.6 percent palladium carbon catalyst.
Evaluation of catalyst: taking the preparation of polyether amine D230 by hydrogenating and aminating polyether polyol PPG-230 (with a bifunctional group and a molecular weight of 230) to prepare polyether amine D230 as an example, a continuous method fixed bed process is adopted for evaluation, wherein before reaction, a catalyst is placed into a reactor, hydrogen with the molar weight 8 times of PPG-230 is introduced, the temperature is increased to 200 ℃, the pressure is increased to 10MPa, after a system is stabilized, PPG-230 and liquid ammonia with the molar weight 8 times are pumped into the reactor by a pump, and the airspeed of PPG-230 is 2.0h-1After a certain period of reaction time, the reaction mixture was filtered. And (4) vacuumizing and distilling to obtain a polyether amine product. By chemical analysis, the reaction conversion rate is 96%, and the primary amine selectivity is 98%.
The influence of different catalyst preparation conditions and application conditions on the synthesis effect of polyetheramine is shown in tables 1 and 2.
After the catalyst is continuously operated for 800 hours by adopting the 0.6 percent palladium-carbon catalyst in the example 8, the activity and the selectivity of the catalyst are kept unchanged, the reaction conversion rate is 96 percent, the selectivity of primary amine is 98 percent, and the catalyst basically does not generate the rehydration phenomenon.
Comparative example 1:
the difference from example 8 is that the catalyst prepared according to the method of preparation of the catalyst in the example of patent US5352835A, 19.9% Ni-7.6% Cu/theta-Al2O3The catalyst has the advantages that after the catalyst is continuously operated for 200 hours, the activity is obviously reduced, the reaction conversion rate is 90.5 percent, and the primary amine selectivity is 98 percent. By X-ray derivative spectroscopy using boehmite peak to theta-Al2O3The integrated intensity of the peaks estimates the degree of rehydration of the alumina component to be 25%. It can be seen that the present invention has excellent hydration resistance and the stability of the catalyst of the present invention is significantly superior to the alumina-supported catalysts of the prior art.
Example 9: catalyst recovery
The catalyst of example 8 was run further and when the catalyst was run continuously for 2500h, the catalyst activity began to decrease significantly, with a reaction conversion of 88.5% and a primary amine selectivity of 92% which needed to be recovered. The waste catalyst is burned for 5 hours at 400 ℃ in a muffle furnace, the temperature is increased to 900 ℃, and the burning is continued for 5 hours, so that 1.2g of palladium slag is obtained. The obtained palladium residue was added to 10.8g of concentrated hydrochloric acid and 3.6g of concentrated nitric acid, and heated in a water bath at 75 ℃ to completely dissolve palladium. Then slowly adding a small amount of ammonia water into the solution while stirring, stopping adding when the pH reaches 8.8, heating in a water bath at 75 ℃ and stirring for 30min, standing and filtering. Then, ammonium chloride solution is added dropwise while stirring, the dropwise addition is stopped when the pH value reaches 2, the mixture is kept stand, filtered, and the precipitate is washed with deionized water for multiple times. And finally, drying the obtained yellow crystal, roasting for 4 hours in a muffle furnace at the temperature of 600 ℃, and deaminating to obtain powdery palladium chloride.
Examples 1 to 8 were collated to give tables 1 and 2.
TABLE 1 influence of different catalyst preparation conditions on the synthesis of polyetheramine D230
TABLE 2 influence of different catalyst application conditions on the Synthesis of polyetheramines
As can be seen from tables 1 and 2, the higher the palladium content in the catalyst, the higher the catalytic activity of the catalyst, the higher the polyether conversion rate and the primary amine selectivity, and meanwhile, compared with polyether with a larger molecular weight, the catalyst is more suitable for catalyzing the hydroamination reaction of polyether polyol with a small molecular weight, and multiple experiments show that under the same conditions, the raw material ratio of hydrogen to polyether is 8:1, the raw material ratio of liquid ammonia to polyether is 8:1, and the polyether space velocity is 2h-1The temperature is 200 ℃, the pressure is 10MPa, and the reaction efficiency is optimal.