A double non-noble metal catalyst Co-Ni / La2O3, a preparation method thereof and application of the catalyst in selective hydrogenation of m-xylylenediamine in a heterogeneous system

Abstract

The present application relates to a kind of double non-noble metal catalyst Co-Ni / La2O3 and its preparation method and the application of selective hydrogenation of m-xylylenediamine in heterogeneous system, belong to catalytic hydrogenation field, the Co-Ni loading of this catalyst is 5wt%, it is cobalt nitrate hexahydrate as cobalt source, nickel nitrate hexahydrate is nickel source, La2O3 is carrier, active metal Co, Ni is loaded on La2O3, reduction and passivation are prepared in tube furnace.The conversion rate of m-xylylenediamine reaches 100% under the conditions of catalyst 50mg, m-xylylenediamine 0.5g, hydrogen pressure 8MPa, temperature 180 DEG C, reaction 5h, and the selectivity of 1,3-cyclohexanedimethylamine reaches more than 70%.The preparation method is simple, low in cost, target product is high in selectivity, has excellent catalytic performance, and easy to separate and has industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalytic hydrogenation, specifically relating to a dual non-noble metal catalyst Co-Ni / La2O3 and its preparation method, as well as its application in the selective hydrogenation of m-phenylenediamine to 1,3-cyclohexanedimethylamine in a heterogeneous system. Background Technology

[0002] 1,3-Cyclohexanedimethylamine is widely used in the synthesis of desulfurizing agents, emulsifiers, and pesticides. It can be prepared from the hydrogenation of the benzene ring of aromatic amines. Noble metal catalysts are widely used in the hydrogenation of aromatic amines, but noble metals are expensive. Therefore, the development of non-noble metal-based catalysts with excellent catalytic performance is of great significance in practical industrial production and application.

[0003] Currently, the catalytic hydrogenation of phenylenediamine to cyclohexanediamine is the most atom-economical route, but most of the catalysts used are noble metal catalysts, namely Ru. Zhao et al. used 8.5 wt% Ru / C as a catalyst, isopropanol as a solvent, and no additives, achieving a 99.5% conversion of o-phenylenediamine and a 77.3% yield of 1,2-cyclohexanediamine at a reaction temperature of 160℃ and a pressure of 7 MPa. Wang Tao et al. from the Dalian Institute of Chemical Physics used 5 wt% Ru / C as a catalyst, isopropanol as a solvent, and sodium nitrite as an additive, achieving a 99.5% conversion of o-phenylenediamine and a 86.3% selectivity for 1,2-cyclohexanediamine at a reaction temperature of 170℃ and a pressure of 8 MPa, and the product selectivity remained above 85% even after five cycles. Lin Xue et al. used isopropanol as a solvent and lithium hydroxide as an additive. Experimental results showed that under conditions of 120℃ and 8 MPa, the conversion rate of p-phenylenediamine was 100%, and the selectivity for the product 1,4-cyclohexanediamine reached 92%, effectively suppressing the formation of the byproduct cyclohexylamine. Liu Qinglin et al. simultaneously employed catalyst activation at 500℃ and alkali treatment, finding that the performance of the treated Ru / C catalyst was significantly improved. Under conditions of 140℃ and 8 MPa, the conversion rate of p-phenylenediamine and the selectivity for 1,4-cyclohexanediamine were 100% and 90%, respectively.

[0004] 1,3-Cyclohexanedimethylamine (1,3-cyclohexanedimethylamine) is an important intermediate in organic and fine chemical industries, widely used in epoxy resins and composite materials. It is also a crucial raw material for the synthesis of isocyanates. The alicyclic isocyanates synthesized from 1,3-cyclohexanedimethylamine do not contain benzene rings, exhibiting relatively stable properties and can be used to prepare polyurethane products with excellent yellowing resistance. When used as an alicyclic amine curing agent, 1,3-cyclohexanedimethylamine offers advantages over alicyclic amines, such as a longer pot life and lighter color. Furthermore, its rigid alicyclic molecular structure provides excellent heat resistance, water resistance, chemical resistance, and mechanical properties. m-Phenylenediamine (m-phenylenediamine) is highly toxic; inhalation of its vapor can cause asthma and other respiratory illnesses. Skin absorption can lead to blood disorders and affect kidney and liver function. Therefore, developing a production process for 1,3-cyclohexanedimethylamine via hydrogenation of m-phenylenediamine is of significant research value. For example, Yang Yanmi et al. from Beijing University of Chemical Technology demonstrated excellent catalytic performance using Ru / Al₂O₃ as a catalyst. Under conditions of 5% Ru loading, a reaction temperature of 130 °C, a reaction pressure of 5 MPa, and tetrahydrofuran as solvent, the conversion of m-phenylenediamine reached 100%, and the selectivity for 1,3-cyclohexanedimethylamine reached 87.7%. With the catalyst modified by LiOH, the yield of 1,3-cyclohexanedimethylamine reached 97.9% under the same conditions. Kim et al., using 5 wt% Ru / C as catalyst, isopropanol as solvent, and sodium nitrate as additive, achieved a 100% conversion of m-phenylenediamine and a 90.6% yield of 1,3-cyclohexanedimethylamine at a reaction temperature of 120 °C and a pressure of 5.4 MPa.

[0005] Current research mainly focuses on using the noble metal Ru supported on activated carbon or alumina as a catalyst. Adding nitrates or treating the catalyst with alkali to create an alkaline environment improves the catalyst's activity and selectivity for cyclohexanediamine. While noble metal catalysts exhibit high reactivity, their high cost limits their industrial application. Therefore, developing non-noble metal catalysts for the hydrogenation of m-phenylenediamine is of great significance. Summary of the Invention

[0006] To address the aforementioned problems in existing catalytic hydrogenation technologies, the present invention aims to provide a dual non-noble metal catalyst, Co-Ni / La₂O₃, its preparation method, and its application in the selective hydrogenation of m-phenylenediamine in a heterogeneous system. This catalyst uses the basic oxide La₂O₃ as a support, loading non-noble metals Co and Ni, which possess strong hydrogenation properties. It enables the catalytic hydrogenation of m-phenylenediamine without any additives. The preparation method is low-cost, provides a fast catalytic hydrogenation rate, and is easily separated, thus possessing broad industrialization prospects.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] One of the objectives of this invention is to provide a dual non-noble metal catalyst Co-Ni / La2O3, wherein Co and Ni are supported on a La2O3 support, and the total loading of Co and Ni is 5 wt% of the catalyst, with Co:Ni = 1:1.

[0009] In the Co-Ni / La2O3 catalyst, the loading of Co and Ni is expressed as 5% in the following text, and its meaning is the same as that of 5 wt% as recorded in this text.

[0010] Preferably, in the above catalyst, the total loading of Co and Ni is 5 wt% of the catalyst, and the mass ratio of Co to Ni is 1:1.

[0011] Another object of the present invention is to provide a method for preparing the Co-Ni / La2O3 dual non-noble metal catalyst, the specific steps of which are as follows:

[0012] (1) Using La2O3 as a carrier, heat and stir it on a heating plate to make it heat evenly;

[0013] (2) Using nickel nitrate hexahydrate as the nickel source, cobalt nitrate hexahydrate as the cobalt source, and uniformly heated La2O3 as the support, an unreduced catalyst Co-Ni / La2O3 was prepared by impregnation method.

[0014] (3) The unreduced catalyst Co-Ni / La2O3 was placed in a tube furnace with a mixed H2 / Ar atmosphere for heating and reduction, and then cooled naturally to room temperature. After that, a mixed O2 / Ar gas was introduced for passivation to obtain the reduced catalyst Co-Ni / La2O3.

[0015] Preferably, in step (1), the temperature of the heating plate is 90°C.

[0016] Preferably, in steps (1) and (2), the mass ratio of La2O3, cobalt nitrate hexahydrate as cobalt source, and nickel nitrate hexahydrate is 1:0.1236:0.0951.

[0017] Preferably, in step (3), the heating temperature in the tubular furnace is 500°C and the heating time is 2 hours.

[0018] Preferably, in step (3), the volume fraction of H2 is 5% and the inlet time is 30 min.

[0019] Preferably, in step (3), the volume fraction of O2 is 0.5% and the introduction time is 30 min.

[0020] The method for selective hydrogenation catalysis of m-phenylenediamine in a heterogeneous system using the dual non-noble metal catalyst Co-Ni / La2O3 of the present invention comprises the following specific steps:

[0021] (1) Select a stainless steel reactor;

[0022] (2) Weigh the prepared catalyst Co-Ni / La2O3 into the reactor, then weigh m-phenylenediamine and dissolve it in tert-butanol solvent. After ultrasonic dispersion, put the mixture into the reactor.

[0023] (3) After sealing the reactor, flush it three times with hydrogen gas at a pressure of 1.0 MPa, maintain the hydrogen pressure at 1.0 MPa at room temperature, and check the airtightness of the reactor.

[0024] (4) Heat the reactor to 180°C and continue to introduce hydrogen gas to 8.0 MPa. Maintain the temperature and pressure inside the reactor for 3-5 hours.

[0025] (5) After the reaction is complete, wait for the reactor to cool to room temperature, open the gas valve, release hydrogen gas until the pressure is 0, and the reaction process is complete.

[0026] The present invention also aims to provide the application of the dual non-noble metal catalyst Co-Ni / La2O3 in the selective hydrogenation catalysis of m-phenylenediamine in a heterogeneous system, wherein the catalyst exhibits a selectivity for 1,3-cyclohexanedimethylamine greater than 70% when the conversion of m-phenylenediamine is 100%.

[0027] By employing the above-described technology, the beneficial effects of the present invention compared to the prior art are as follows:

[0028] 1) The catalyst of the present invention is prepared by impregnation method, using non-precious metals as the active phase, which greatly reduces the cost of raw materials, and the preparation process is simple, energy-saving, green and environmentally friendly.

[0029] 2) The catalyst prepared by this invention has high catalytic performance when the total loading is 5%. Specifically, under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 5 h reaction time and 50 mg catalyst, the selectivity for 1,3-cyclohexanedimethylamine reaches more than 70% when the conversion rate of 0.5 g m-phenylenediamine is 100%. Attached Figure Description

[0030] Figure 1 These are X-ray diffraction analysis diagrams of the catalysts prepared in different embodiments of the present invention;

[0031] As can be seen from the figure, compared with the JCPDS standard data of lanthanum oxide, elemental cobalt and elemental nickel, the characteristic peaks of lanthanum oxide are obvious, but no obvious characteristic diffraction peaks of Co and Ni are detected. This is because the loading of Co and Ni in the catalyst is low and the dispersion of the loaded metal is high.

[0032] Figure 2This is a scanning electron microscope image of the catalyst prepared in Example 1 of the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0034] This invention uses different proportions of Co and Ni loaded on La2O3 as examples, and Co and Ni loaded on different oxide supports as comparative examples. The specific preparation process is as follows.

[0035] (1) Using 1g of La2O3 as a carrier, heat and stir it on a 90℃ heating plate to make it heat evenly;

[0036] (2) Using 0.1236 g of cobalt nitrate hexahydrate as the cobalt source and 0.0951 g of nickel nitrate hexahydrate as the nickel source, they were mixed and dissolved in 2 mL of pure water. The unreduced catalyst Co-Ni / La2O3 was prepared by impregnation. The cobalt-nickel precursor Co-Ni / La2O3 mixture was added dropwise to the dry La2O3 support and stirred until it was completely added and dried.

[0037] (3) The unreduced catalyst Co-Ni / La2O3 was placed in a tube furnace under an H2 / Ar atmosphere for heating and reduction. The heating rate of the tube furnace was 5℃ / min, the heating temperature of the tube furnace was 500℃, the heating time was 2h, the volume fraction of H2 in the mixed gas was 5%, the introduction time was 2h, and after naturally cooling to room temperature, a mixed gas of O2 / Ar was introduced for passivation. The volume fraction of O2 was 0.5%, the introduction time was 30min, and Co-Ni / La2O3 was obtained.

[0038] The application of the catalyst prepared above in the catalytic hydrogenation of m-phenylenediamine was tested, and the performance testing steps are as follows:

[0039] Performance testing was conducted in a 100mL stainless steel reactor. 50mg of the catalyst Co-Ni / La2O3 was weighed into the reactor, along with 0.5g of m-phenylenediamine and 30mL of tert-butanol. The m-phenylenediamine was dissolved in the tert-butanol and ultrasonically dispersed until homogeneous. The mixture was then placed into the reactor. After sealing the reactor, it was flushed three times with hydrogen gas (1MPa). The hydrogen pressure was increased by 1MPa at room temperature, and the airtightness was checked. After checking the airtightness, the magnetic rotation speed was adjusted to 500rpm, and the reactor temperature was raised to 180℃. Hydrogen gas was then introduced until the pressure reached 8MPa, and timing began. After 3 hours of reaction, the reactor was allowed to cool to room temperature. The gas valve was then opened to release hydrogen gas until the pressure reached 0MPa.

[0040] After filtering the reaction solution, 0.4 μL was injected into the gas chromatograph using a microsyringe. The gas chromatograph parameters were set as follows: hydrogen flow rate 40–60 mL / min, air flow rate 260–300 mL / min, and carrier gas flow rate 2–4 mL / min. The injection temperature was set to 280.0 °C, the column furnace temperature to 150.0 °C, and the FID temperature to 280.0 °C. Using n-dodecane as an internal standard, the conversion rate of the catalyst to m-phenylenediamine and the selectivity for 1,3-cyclohexanedimethylamine were calculated by gas chromatography.

[0041] Example 1: Application test of 5% Co-Ni / La2O3 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0042] The Co-Ni / La2O3 catalyst of Example 1, wherein the loading of Co and Ni is 5% of the catalyst and the ratio of Co to Ni is 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0043] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 72%, and the conversion rate of 1,3-cyclohexanedimethylamine was 71.3%.

[0044] Example 2: Application test of 3% Co-Ni / La2O3 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0045] The Co-Ni / La2O3 catalyst of Example 2, wherein the loading of Co and Ni is 3% of the catalyst and the ratio of Co to Ni is 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0046] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 32.7%, and the conversion rate of 1,3-cyclohexanedimethylamine was 28.6%.

[0047] Example 3: Application test of 7% Co-Ni / La2O3 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0048] The Co-Ni / La2O3 catalyst of Example 3, wherein the loading of Co and Ni is 7% of the catalyst and the ratio of Co to Ni is 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine:

[0049] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 99.9%, and the conversion rate of 1,3-cyclohexanedimethylamine was 32.6%.

[0050] Example 4: Application test of 5% Co-Ni / La2O3 (Co:Ni = 1:0.5) in the catalytic hydrogenation of m-phenylenediamine

[0051] The Co-Ni / La2O3 catalyst of Example 4, wherein the loading of Co and Ni is 5% of the catalyst and the ratio of Co to Ni is 1:0.5, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0052] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 99.9%, and the conversion rate of 1,3-cyclohexanedimethylamine was 32.6%.

[0053] Example 5: Application test of 5% Co-Ni / La2O3 (Co:Ni = 1:2) in the catalytic hydrogenation of m-phenylenediamine

[0054] The Co-Ni / La2O3 catalyst of Example 5, wherein the loading of Co and Ni is 5% of the catalyst and the ratio of Co to Ni is 1:2, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0055] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 90.8%, and the conversion rate of 1,3-cyclohexanedimethylamine was 51.6%.

[0056] Application test of 1:5% Co-Ni / TiO2 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0057] The rutile TiO2 catalyst Co-Ni / TiO2 of Comparative Example 1, with a loading of 5% for metals Co and Ni, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0058] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g p-chloronitrobenzene, the catalyst conversion rate was 24.8%, and the selectivity for 1,3-cyclohexanedimethylamine was 10.2%.

[0059] Application test of 2:5% Co-Ni / CeO2 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0060] The CeO2-supported Co-Ni / CeO2 catalyst of Comparative Example 2, wherein the loading of metallic Co and Ni is 5% and the Co:Ni = 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0061] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 99.9% and the selectivity of m-phenylenediamine was 31.6%.

[0062] Application test of 3:5% Co-Ni / SiO2 (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0063] The SiO2-supported Co-Ni / CeO2 catalyst of Comparative Example 3, wherein the loading of metals Co and Ni is 5% and the Co:Ni = 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0064] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 12.6% and the selectivity of m-phenylenediamine was 9.5%.

[0065] Application test of 4:5% Co-Ni / MgO (Co:Ni = 1:1) in the catalytic hydrogenation of m-phenylenediamine

[0066] The MgO2-supported Co-Ni / MgO2 catalyst of Comparative Example 4, wherein the loading of metal Co and Ni is 5% and the Co:Ni = 1:1, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0067] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 78.3% and the selectivity of m-phenylenediamine was 26.7%.

[0068] Application test of 5:5% Co / La2O3 in the catalytic hydrogenation of m-phenylenediamine

[0069] The Co / La2O3 catalyst supported on Co in Comparative Example 5, wherein the Co loading was 5%, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0070] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 20.5% and the selectivity of m-phenylenediamine was 27.7%.

[0071] Application test of Ni / La2O3 (comparative ratio 6:5%) in the catalytic hydrogenation of m-phenylenediamine

[0072] The Ni / La2O3 catalyst, with a Ni loading of 5%, supported on La2O3 in Comparative Example 6, was tested in the catalytic hydrogenation of m-phenylenediamine.

[0073] Under the reaction conditions of 8 MPa hydrogen pressure, 180 °C temperature, 3 h reaction time, 50 mg catalyst, and 0.5 g m-phenylenediamine, the catalyst conversion rate was 99.9% and the selectivity of m-phenylenediamine was 45.4%.

[0074] By comparing the effects of different supports on catalytic performance, the performance and parameters of the products were obtained, and the optimal performance of the products was determined. Table 1 shows the results and comparative cases of catalyst products obtained under different support conditions.

[0075] Table 1: Effect of different supported catalysts on the hydrogenation of m-phenylenediamine

[0076]

[0077] The amount of catalyst was 5%, and the ratio of Co to Ni was 1:1. The catalyst was 50 mg, the amount of m-phenylenediamine was 0.5 g, the amount of tert-butanol was 30 mL, the temperature was 180 °C, the hydrogen pressure was 8 MPa, the reaction time was 3 h, and the catalyst reducing atmosphere was 5% H2 / Ar.

[0078] As can be seen from Table 1, different supports have a significant impact on the activity. Using La2O3 as a support can significantly improve the activity of the catalyst and the selectivity for m-phenylenediamine.

[0079] By studying the effects of different element loadings on the catalytic performance of catalysts, the performance and parameters of the products were obtained through testing, and the optimal performance of the products was determined through analysis. Table 2 shows the results and comparative cases obtained by testing the performance of catalyst products with different element loadings.

[0080] Table 2: Effect of different metal loading on catalyst activity

[0081]

[0082] Reaction conditions: Co:Ni = 1:1, catalyst 50mg, m-phenylenediamine 0.5g, tert-butanol 30mL, temperature 180℃, hydrogen pressure 8MPa, reaction time 3h.

[0083] As shown in Table 2, although the conversion rate of m-phenylenediamine is high when the metal loading is 7%, a large number of byproducts are generated, and the selectivity of 1,3-cyclohexanedimethylamine is low. Therefore, a loading of 5% is considered the optimal loading.

[0084] By studying the effect of the Co / Ni loading ratio on the catalytic performance of the catalyst, the performance and parameters of the product were obtained, and the optimal performance of the product was determined through analysis. Table 3 shows the performance results of catalyst products with different Co / Ni loading ratios.

[0085] Table 3: Effect of different Co:Ni ratios on catalyst activity

[0086]

[0087] Reaction conditions: catalyst loading of 5%, catalyst 50mg, m-phenylenediamine 0.5g, tert-butanol 30mL, temperature 180℃, hydrogen pressure 8MPa, reaction time 3h.

[0088] As can be seen from Table 3, the yield of 1,3-cyclohexanedimethylamine is higher when Co:Ni = 1:1.

[0089] This study investigated the effect of catalytic reaction time on the catalytic performance of the catalyst during the reaction of xylene, and analyzed and determined the optimal performance of the product. Table 4 shows the effect of different catalytic reaction times on the catalyst performance, and the results of the performance evaluation.

[0090] Table 4: Effect of reaction time on catalytic activity

[0091]

[0092] Reaction conditions: 50 mg of 5% Co-Ni / La2O3 catalyst (Co:Ni = 1:1), 0.5 g of m-phenylenediamine, 30 mL of tert-butanol, temperature 180℃, hydrogen pressure 8 MPa, reducing atmosphere 5% H2 / Ar.

[0093] As can be seen from Table 4, with the extension of reaction time, m-phenylenediamine is completely converted in 5 hours, and the selectivity of 1,3-cyclohexanedimethylamine is >70% when completely converted.

[0094] The effect of the volume fraction of hydrogen in the reducing atmosphere on the catalytic reaction of xylene was studied, and the optimal reaction performance of the product was determined. Table 5 shows the results of the effect of different reducing atmospheres on the catalytic reaction.

[0095] Table 5: Effect of different reducing atmospheres on catalyst activity

[0096]

[0097] Reaction conditions: catalyst loading of 5%, Co:Ni = 1:1, catalyst 50mg, m-phenylenediamine 0.5g, tert-butanol 30mL, temperature 180℃, hydrogen pressure 8MPa, reaction time 3h.

[0098] As can be seen from Table 5, a reducing atmosphere of 5% H2 / Ar resulted in a higher conversion rate of m-phenylenediamine and a higher selectivity for 1,3-cyclohexanedimethylamine, which may be attributed to the milder reducing atmosphere resulting in smaller catalyst particle size after reduction.

[0099] The above description is only a partial embodiment of the present invention and is not intended to limit the present invention. Any equivalent changes and modifications made based on the content of this invention are within the protection scope of this invention.

Claims

1. The application of a dual non-noble metal catalyst Co-Ni / La2O3 in the selective hydrogenation of m-phenylenediamine in a heterogeneous system, characterized in that, The catalyst exhibits a selectivity greater than 70% for 1,3-cyclohexanedimethylamine at a conversion rate of 100%; and in this catalyst, Co and Ni are supported on La2O3, with the total loading of Co and Ni being 3-7 wt% of the catalyst, and the mass ratio of Co:Ni being 1:0.5-2.

2. The application according to claim 1, characterized in that, The total loading of Co and Ni is 5 wt% of the catalyst, and the mass ratio of Co to Ni is 1:

1.

3. The application according to claim 1, characterized in that, The specific steps for using this catalyst are as follows: (1) Using La2O3 as a carrier, heat and stir it on a heating plate to make it heat evenly; (2) Using cobalt nitrate hexahydrate as the cobalt source and nickel nitrate hexahydrate as the nickel source, they were mixed and dissolved in pure water. The unreduced catalyst Co-Ni / La2O3 was prepared by impregnation. The cobalt-nickel precursor mixture was added dropwise to the dry support and stirred evenly until all the mixture was added and dried. (3) The unreduced catalyst Co-Ni / La2O3 was placed in a tube furnace under H2 / Ar atmosphere for heating and reduction. After naturally cooling to room temperature, a mixture of O2 / Ar gas was introduced for passivation to obtain Co-Ni / La2O3.

4. The application according to claim 3, characterized in that, In step (1), the temperature of the heating plate is 90 ℃.

5. The application according to claim 3, characterized in that, In steps (1) and (2), the mass ratio of La2O3, cobalt nitrate hexahydrate as the cobalt source, and nickel nitrate hexahydrate is 1:0.1236:0.0951.

6. The application according to claim 3, characterized in that, In step (3), the heating rate of the tubular furnace is 5 °C / min.

7. The application according to claim 3, characterized in that, In step (3), the reduction temperature of the tubular furnace is 500℃ and the heating time is 2 h.

8. The application according to claim 3, characterized in that, In step (3), the volume fraction of H2 in the mixed gas is 5%, and the introduction time is 2 h.

9. The application according to claim 3, characterized in that, In step (3), the volume fraction of O2 in the mixed gas is 0.5%, and the introduction time is 30 min.

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