Preparation method and application of microenvironment-induced high-stability copper-based bifunctional catalyst

Abstract

The application discloses a preparation method and application of a microenvironment-induced high-stability copper-based bifunctional catalyst, and the preparation method comprises the following steps: 1) a chromium-modified hydroxyapatite carrier is prepared by adopting a cation exchange method; 2) a catalyst precursor is prepared by deposition precipitation; and 3) a chromium-modified hydroxyapatite loaded high-stability copper-based bifunctional nanometer catalyst is prepared by reduction. The catalyst prepared by the application has hydrogenation function and alkylation function, and can realize one-step synthesis of N-methyl aniline. In particular, the microenvironment-induced synthesis strategy can significantly enhance the stability of the copper-based catalyst, and the preparation method is simple, low in cost and easy to be applied in industrialization.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, and in particular to a method for preparing and applying a microenvironment-induced highly stable copper-based bifunctional catalyst. Background Technology

[0002] N-Methylaniline is a high-value-added fine chemical widely used in pharmaceuticals, pesticides, dyes, and other fields. Currently, the main industrial synthesis process uses nitrobenzene, hydrogen, and methanol as raw materials, involving a two-step reaction of hydrogenation and alkylation. Nitrobenzene is first hydrogenated to produce aniline, which is then methylated to obtain N-methylaniline. This process has high conversion efficiency but is cumbersome and costly. By cascading the hydrogenation and alkylation reactions in a series, a one-step synthesis of N-methylaniline can improve production efficiency and reduce costs, which has significant economic and social implications.

[0003] Currently, the catalysts used in the one-step synthesis of N-methylaniline are mainly noble metal-based catalysts (Pt / Pd / Rh / Ru / Ir, etc.), Raney nickel, and supported non-noble metal catalysts. The large-scale application of noble metal catalysts is limited by their high cost and low reserves. Raney nickel catalysts are highly flammable in air, posing safety concerns; furthermore, they are unsuitable for continuous production. Supported non-noble metal catalysts have attracted widespread attention due to their low cost, availability, and applicability to various scenarios. Among supported non-noble metal catalysts, copper-based catalysts exhibit excellent catalytic activity and selectivity in the one-step synthesis of N-methylaniline from nitrobenzene. However, in the above reaction, the copper active component is prone to agglomeration, reducing reaction activity. Therefore, the one-step synthesis of N-methylaniline suffers from the problem of poor stability of copper-based supported catalysts. Summary of the Invention

[0004] In view of the aforementioned defects or deficiencies in the existing technology, it is desirable to provide a method for preparing and applying a microenvironment-induced highly stable copper-based bifunctional catalyst. This technical solution prepares a chromium-modified hydroxyapatite support through a cation exchange reaction. Utilizing the strong interaction between the localized Cr-O microenvironment and copper, the stability of copper nanoparticles is enhanced, constructing a bifunctional catalyst that can perform both hydrogenation and alkylation. This achieves a highly efficient one-step synthesis of N-methylaniline, with simple operation, low cost, and ease of industrial production.

[0005] This invention provides a microenvironment-induced highly stable copper-based bifunctional catalyst and its preparation method, comprising the following steps:

[0006] 1) Preparation of chromium-modified hydroxyapatite (Cr-HAP);

[0007] 2) Copper nitrate solution was added dropwise to the Cr-HAP support dispersion. During the addition, the pH of the system was controlled to be 9 by using Na2CO3 solution. The reaction was continued by heating. After aging, filtration, washing, drying and calcination, the catalyst precursor was obtained.

[0008] 3) The catalyst precursor was reduced in a hydrogen atmosphere to obtain the target catalyst Cu / Cr-HAP.

[0009] Furthermore, in step 1), the preparation of the microenvironment-induced highly stable copper-based bifunctional nanocatalyst includes the following steps:

[0010] 11) By mass, dissolve 1 part of diammonium hydrogen phosphate and 3 parts of calcium nitrate tetrahydrate in 10-20 parts of deionized water. Under stirring, simultaneously add the above solutions dropwise to 3-4 parts of ammonia solution. Then continue the reaction in an 80°C water bath for 2-10 hours. After stopping stirring, age for 6-24 hours, filter, wash with water until neutral, dry, and calcine in a muffle furnace at 500°C to obtain HAP.

[0011] 12) Disperse 1 part HAP into 4-10 parts deionized water by mass, add 0-2 parts chromium nitrate nonahydrate while stirring, continue the reaction for 2-12 hours, stop stirring, filter, wash with water, and dry to obtain Cr-HAP.

[0012] Furthermore, in step 2), the heating temperature is 50-80℃ and the aging time is 6-24h.

[0013] Furthermore, in step 2), the calcination temperature is 400-700℃, and the holding time is 2-12h.

[0014] Furthermore, in step 3), the reduction temperature is 300-500℃ and the holding time is 1-8h.

[0015] In addition, the present invention also provides the application of a microenvironment-induced highly stable copper-based bifunctional nanocatalyst in the one-step synthesis of N-methylaniline.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] This invention designs a bifunctional catalyst that combines hydrogenation and alkylation functions. Of particular note is the development of a method that significantly enhances the stability of copper-based nanocatalysts, greatly extending the catalyst's lifespan in the one-step synthesis of N-methylaniline. Compared to existing technologies, this invention first prepares a chromium-modified hydroxyapatite support via a cation exchange reaction. Utilizing the strong interaction between the localized Cr-O microenvironment within the chromium-modified hydroxyapatite support and the copper component, the aggregation of the copper component during the catalytic reaction is suppressed, significantly improving catalyst stability. Therefore, this invention possesses outstanding substantive features and significant advancements, making it particularly suitable for the one-step green synthesis of N-methylaniline. Furthermore, the catalyst preparation method in this invention is simple, low-cost, and easy to scale up for mass production.

[0018] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0019] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0020] Figure 1 This is a schematic diagram of a highly stable copper-based bifunctional catalyst induced by the Cr-O microenvironment in the Cr-HAP support.

[0021] Figure 2 Cu for Example 1 and Comparative Examples 1-4 10 / Cr-HAP, Cu 10 / HAP, Cu 10 / Zn-HAP, Cu 10 / Co-HAP and Cu 10 XRD pattern of / Ni-HAP;

[0022] Figure 3 Cu for Example 1 and Comparative Examples 1-4 10 / Cr-HAP, Cu 10 / HAP, Cu 10 / Zn-HAP, Cu 10 / Co-HAP and Cu 10 H2-TPR spectrum of / Ni-HAP;

[0023] Figure 4 Cu from Example 1 10 Cyclic stability results of / Cr-HAP in the one-step synthesis of N-methylaniline;

[0024] Figure 5 Cu for Comparative Example 1 10 Cyclic stability results of / HAP in the one-step synthesis of N-methylaniline;

[0025] Figure 6 Cu for Comparative Example 2 10 Cyclic stability results of Zn-HAP in the one-step synthesis of N-methylaniline;

[0026] Figure 7 Cu for Comparative Example 3 10 Cyclic stability results of / Co-HAP in the one-step synthesis of N-methylaniline;

[0027] Figure 8 Cu for Comparative Example 4 10 Cyclic stability results of Ni-HAP in the one-step synthesis of N-methylaniline;

[0028] Figure 9 Cu for Example 5 10 Cyclic stability results of Cr5 / HAP in the one-step synthesis of N-methylaniline;

[0029] Figure 10 Cu for Example 6 10 Cyclic stability results of / Cr-Al2O3 in the one-step synthesis of N-methylaniline;

[0030] Figure 11 Cu for Comparative Example 1 10 Cyclic stability results of Cr5 / Al2O3 in the one-step synthesis of N-methylaniline;

[0031] Figure 12 Cu for Example 7 10 Cyclic stability results of / Cr-SiO2 in the one-step synthesis of N-methylaniline;

[0032] Figure 13 Cu for Comparative Example 1 10 Cyclic stability results of Cr5 / SiO2 in the one-step synthesis of N-methylaniline;

[0033] Figure 14 Cu for Example 8 10 Cyclic stability results of / Cr-TiO2 in the one-step synthesis of N-methylaniline;

[0034] Figure 15 Cu for Comparative Example 1 10 Cyclic stability results of Cr5 / TiO2 in the one-step synthesis of N-methylaniline. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example 1

[0038] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-HAP.

[0039] 2.62 g Cr-HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. The sample was then placed in a reduction furnace and heated to 300℃ at a rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain a highly stable copper-based bifunctional nanocatalyst Cu induced by the microenvironment. 10 / Cr-HAP.

[0040] Comparative Example 1

[0041] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. Under stirring, the above solutions were simultaneously added dropwise to 10 mL of ammonia water, and then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered and washed with deionized water until the pH value was 7. The mixture was then transferred to an oven and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support.

[0042] 2.62 g HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / HAP.

[0043] Comparative Example 2

[0044] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of zinc nitrate hexahydrate solution (0.09 M) was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Zn-HAP.

[0045] 2.62 g Zn-HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Zn-HAP.

[0046] Comparative Example 3

[0047] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of cobalt nitrate hexahydrate solution (0.1 M) was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Co-HAP.

[0048] 2.62 g of Co-HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a rate of 5 °C / min, and held at this temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Co-HAP.

[0049] Comparative Example 4

[0050] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of nickel nitrate hexahydrate solution (0.1 M) was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Ni-HAP.

[0051] 2.62 g of Ni-HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a rate of 5 °C / min, and held for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Ni-HAP.

[0052] Cu in Example 1 10 / Cr-HAP and Cu in Comparative Examples 1-4 10 / HAP, Cu 10 / Zn-HAP, Cu 10 / Co-HAP, Cu 10 / Ni-HAP underwent XRD testing, and the results are as follows: Figure 1 As shown in the figure, the modification with Cr metal did not change the structure of the hydroxyapatite support; compared with other metals, the modification with Cr metal can significantly reduce the grain size of the reduced copper nanoparticles.

[0053] Cu in Example 1 10 / Cr-HAP and Cu in Comparative Examples 1-4 10 / HAP, Cu 10 / Zn-HAP, Cu 10 / Co-HAP, Cu 10 / Ni-HAP underwent H2-TPR testing, and the results are as follows Figure 2 As shown in the figure, compared with other metals (Zn / Co / Ni), Cr modification can significantly reduce the reduction temperature of Cu. This may be because the modification of the hydroxyapatite support with Cr metal creates a local Cr-O microenvironment, which, through its strong interaction with copper species, induces the preparation of copper components with smaller grain sizes, thereby reducing the reduction temperature.

[0054] The Cu in Example 1 was examined 10 / Cr-HAP and Cu in Comparative Examples 1-4 10 / HAP, Cu 10 / Zn-HAP, Cu 10 / Co-HAP, Cu 10 The stability of / Ni-HAP in the one-step synthesis of N-methylaniline was shown in the following results. Figure 3 As shown in the figure. It can be seen from the figure that Cu 10 After four cycles, the activity of / HAP decreased significantly, and the loading of other metals (Zn / Co / Ni) did not improve its stability; Cr modification enabled the catalyst to be stably cycled 13 times. These results indicate that Cr metal modification can significantly enhance the stability of supported Cu-based nanocatalysts, enabling a highly efficient one-step synthesis of N-methylaniline.

[0055] Example 2

[0056] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-HAP.

[0057] 5.62 g HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. The material was then placed in a reduction furnace and heated to 300°C at a rate of 10°C / min under a 10% H2 / Ar atmosphere. The temperature was then maintained for 2 hours to obtain a highly stable copper-based bifunctional nanocatalyst Cu5 / Cr-HAP induced by the microenvironment.

[0058] Example 3

[0059] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-HAP.

[0060] 1.62 g HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.1405 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. The sample was then placed in a reduction furnace and heated to 300℃ at a rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain a highly stable copper-based bifunctional nanocatalyst Cu induced by the microenvironment. 15 / Cr-HAP.

[0061] Example 4

[0062] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. While stirring, 10 mL of ammonia water was added dropwise to the above solutions simultaneously. The mixture was then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered, washed with deionized water until the pH reached 7, transferred to an oven, and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support. 2.22 g of HAP was dispersed in 30 mL of deionized water. While stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was complete, the reaction was continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-HAP.

[0063] 1.12 g Cr-HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.1405 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. The sample was then placed in a reduction furnace and heated to 300℃ at a rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain a highly stable copper-based bifunctional nanocatalyst Cu induced by the microenvironment. 20 / Cr-HAP.

[0064] Example 5

[0065] 9.44 g of Ca(NO3)2·4H2O and 3.17 g of (NH4)2HPO4 were dissolved in 50 mL of deionized water and stirred until dissolved. Under stirring, the above solutions were simultaneously added dropwise to 10 mL of ammonia water, and then placed in an 80 °C water bath and stirred for 4 h. After stirring was stopped, the mixture was aged for 12 h, then filtered and washed with deionized water until the pH value was 7. The mixture was then transferred to an oven and dried at 120 °C for 4 h. The dried precursor was then transferred to a muffle furnace and calcined at 500 °C for 4 h at a heating rate of 5 °C / min to obtain the HAP support.

[0066] 2.22 g HAP was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate and 1.15 g chromium nitrate nonahydrate were dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The obtained sample was then transferred to an oven and dried at 120°C for 4 hours. Finally, the dried sample was transferred to a muffle furnace and heated to 500°C at a rate of 5°C / min, and held for 4 hours to obtain the catalyst precursor. This precursor was then placed in a reduction furnace and heated to 300°C at a rate of 10°C / min under a 10% H₂ / Ar atmosphere, and held for 2 hours to obtain Cu. 10 Cr5 / HAP catalyst.

[0067] Example 6

[0068] 2.22 g of Al2O3 was dispersed in 30 mL of deionized water. Under stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was completed, the reaction continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-Al2O3.

[0069] 2.62 g of Cr-Al₂O₃ was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a rate of 5 °C / min, and held at this temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Cr-Al2O3 catalyst.

[0070] Comparative Example 1

[0071] 2.22 g of Al₂O₃ was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate and 1.15 g of chromium nitrate nonahydrate were dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na₂CO₃ solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na₂CO₃ solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The obtained sample was then transferred to an oven and dried at 120°C for 4 hours. Finally, the dried sample was transferred to a muffle furnace and heated to 500°C at a rate of 5°C / min, and held for 4 hours to obtain the catalyst precursor. This precursor was then placed in a reduction furnace and heated to 300°C at a rate of 10°C / min under a 10% H₂ / Ar atmosphere, and held for 2 hours to obtain Cu. 10 Cr5 / Al2O3 catalyst.

[0072] Example 7

[0073] 2.22 g SiO2 was dispersed in 30 mL of deionized water. Under stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was completed, the reaction continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-SiO2.

[0074] 2.62 g Cr-SiO2 was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. 12 wt% Na2CO3 solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na2CO3 solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Cr-SiO2 catalyst.

[0075] Comparative Example 1

[0076] 2.22 g of SiO2 was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate and 1.15 g of chromium nitrate nonahydrate were dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na2CO3 solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na2CO3 solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The obtained sample was then transferred to an oven and dried at 120°C for 4 hours. Finally, the dried sample was transferred to a muffle furnace and heated to 500°C at a rate of 5°C / min, and held for 4 hours to obtain the catalyst precursor. This precursor was then placed in a reduction furnace and heated to 300°C at a rate of 10°C / min under a 10% H₂ / Ar atmosphere, and held for 2 hours to obtain Cu. 10 Cr5 / SiO2 catalyst.

[0077] Example 8

[0078] 2.22 g TiO2 was dispersed in 30 mL of deionized water. Under stirring, 27 mL of 0.1 M chromium nitrate nonahydrate solution was slowly added. After the addition was completed, the reaction continued for 4 h, aged for 12 h, filtered, washed with water, and dried to obtain Cr-TiO2.

[0079] 2.62 g of Cr-TiO2 was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g of copper nitrate trihydrate was dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na2CO3 solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH of the solution to 9. Subsequently, solutions A and B were added dropwise to the above solution, and the pH was maintained at around 9 by adding Na2CO3 solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, and then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH value reached 7. The resulting sample was then transferred to an oven and dried at 120 °C for 4 h. Finally, the dried sample was transferred to a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 4 h to obtain the catalyst precursor. It was then placed in a reduction furnace and heated to 300℃ at a heating rate of 10℃ / min under a 10% H2 / Ar atmosphere, and held for 2 hours to obtain Cu. 10 / Cr-TiO2 catalyst.

[0080] Comparative Example 1

[0081] 2.22 g TiO2 was dispersed in 30 mL of deionized water, denoted as solution A. 1.14 g copper nitrate trihydrate and 1.15 g chromium nitrate nonahydrate were dissolved in 40 mL of deionized water, denoted as solution B. A 12 wt% Na2CO3 solution was denoted as solution C. Solution C was added dropwise to 300 mL of deionized water at 60 °C to adjust the pH to 9. Then, solutions A and B were added dropwise to the above solution, and the pH was maintained at approximately 9 by adding Na2CO3 solution. After the addition was complete, the reaction solution was stirred in a 60 °C water bath for 4 h, then aged for 12 h after stirring was stopped. The solution was then filtered and washed with deionized water until the pH reached 7. The obtained sample was then transferred to an oven and dried at 120°C for 4 hours. Finally, the dried sample was transferred to a muffle furnace and heated to 500°C at a rate of 5°C / min, and held for 4 hours to obtain the catalyst precursor. This precursor was then placed in a reduction furnace and heated to 300°C at a rate of 10°C / min under a 10% H₂ / Ar atmosphere, and held for 2 hours to obtain Cu. 10 Cr5 / TiO2 catalyst.

[0082] In the description of this specification, the terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0083] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a microenvironment-induced highly stable copper-based bifunctional catalyst, characterized in that, Includes the following steps: 1) Chromium-modified hydroxyapatite (Cr-HAP) was prepared by cation exchange. 2) Copper nitrate solution was added dropwise to the Cr-HAP support dispersion. During the addition, the pH of the system was controlled to be 9 by using Na2CO3 solution. The reaction was continued by heating. After aging, filtration, washing, drying and calcination, the catalyst precursor was obtained. 3) The catalyst precursor was reduced in a hydrogen atmosphere to obtain the target catalyst Cu / Cr-HAP.

2. The method for preparing the microenvironment-induced highly stable copper-based bifunctional catalyst according to claim 1 utilizes the strong interaction induced by the Cr-O microenvironment localized in Cr-HAP to improve the stability of copper nanoparticles.

3. The method for preparing a highly stable copper-based bifunctional catalyst induced by a microenvironment according to claim 1, characterized in that, In step 1), the preparation of the Cr-HAP support includes the following steps: 11) By mass, dissolve 1 part of diammonium hydrogen phosphate and 3 parts of calcium nitrate tetrahydrate in 10-20 parts of deionized water. Under stirring, simultaneously add the above solutions dropwise to 3-4 parts of ammonia solution. Then continue the reaction in an 80°C water bath for 2-10 hours. After stopping stirring, age for 6-24 hours, filter, wash with water until neutral, dry, and calcine in a muffle furnace at 500°C to obtain HAP. 12) Disperse 1 part HAP into 4-10 parts deionized water by mass, add 0-2 parts chromium nitrate nonahydrate while stirring, continue the reaction for 2-12 hours, stop stirring, filter, wash with water, and dry to obtain Cr-HAP.

4. The method for preparing a microenvironment-induced highly stable copper-based bifunctional catalyst according to claim 1, characterized in that, In step 2), the heating temperature is 50-80℃ and the aging time is 6-24h.

5. The method for preparing a microenvironment-induced highly stable copper-based bifunctional catalyst according to claim 1, characterized in that, In step 2), the calcination temperature is 400-700℃ and the holding time is 2-12h.

6. The method for preparing a microenvironment-induced highly stable copper-based bifunctional catalyst according to claim 1, characterized in that, In step 3), the reduction temperature is 300-500℃ and the holding time is 1-8h.

7. A microenvironment-induced highly stable copper-based bifunctional catalyst prepared by the preparation method according to any one of claims 1-6.

8. The application of a microenvironment-induced highly stable copper-based bifunctional catalyst as described in claim 7 in the one-step synthesis of N-methylaniline via catalytic hydrogenation-alkylation.

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