CN111151283A

CN111151283A - Nitrogen-cobalt co-doped porous carbon loaded sulfur-zinc-cobalt catalytic material and preparation method and application thereof

Info

Publication number: CN111151283A
Application number: CN202010042075.1A
Authority: CN
Inventors: 刘又年; 安平; 张广吉; 王立强; 唐飞鹰
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-01-15
Filing date: 2020-01-15
Publication date: 2020-05-15
Anticipated expiration: 2040-01-15
Also published as: CN111151283B

Abstract

The invention discloses nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material and its preparation method and application. Nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material consisting of protein-metal ion (Zn)²⁺/Co²⁺) The complex is obtained after pyrolysis and acid washing. Nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material having high-efficiency active center (CoN)_xAnd Co_xZnS) and a unique porous structure, has higher efficiency in the catalytic hydrogenation reaction of nitro compounds, good selectivity and mild condition(90℃、5bar H₂) In particular at normal temperature and pressure (25 ℃, 1bar H)₂) Can realize catalytic hydrogenation of nitro compound, so that nitro compound can be efficiently and selectively catalytically converted into corresponding amine compound, and the catalytic material can be used for catalyzing CO and H₂S poisoning exhibits significant tolerance. In addition, the catalytic material has simple synthesis method and wide application prospect in the technical field of catalytic hydrogenation.

Description

Nitrogen-cobalt co-doped porous carbon loaded sulfur-zinc-cobalt catalytic material and preparation method and application thereof

Technical Field

The invention relates to a catalytic material, in particular to a nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material (CoN)_x-Co_xZnS @ NPCs), and to the use of protein-zinc/cobalt ions (Zn)²⁺/Co²⁺) Construction of nitrogen-cobalt Co-doped porous carbon loaded Co by network precursor_xZnS catalytic material method and Co-loaded porous carbon Co-doped with nitrogen and cobalt_xThe application of ZnS catalytic material in the selective hydrogenation of nitro compound under mild condition belongs to the field of heterogeneous catalytic material technology.

Background

Amines and their derivatives are important bulk chemicals and industrial intermediates for the production of pharmaceuticals, pigments, agrochemicals, dyes and fine chemicals. The reduction of nitro compounds provides an extremely important route to amine production, and catalytic hydrogenation reactions using hydrogen as the reducing agent are receiving increasing attention because they are environmentally friendly, economical, and produce few by-products. Noble metal (e.g., Pd, Pt, Au) catalysts are the most active and most used catalysts. However, the high price severely restricts the large-scale popularization in industrial production. In addition, noble metal catalysts are susceptible to trace amounts of CO or H₂Poisoning of S, these gases often take part in H₂In the production or hydrogenation reaction of (a). In addition, noble metal catalyst systems typically have poor hydrogenation selectivity. de-NO₂In addition, other unsaturated functional groups, such as-C ═ C-, -CHO, -C ≡ C-, -CN, and the like, may also be reduced. Thus, low cost, high performance, CO/H resistance₂The S-substituted hydrogenation catalyst is an ideal choice for nitro compound reduction.

Recently, Beller and coworkers reported FeO supported on N-doped carbon_xOr CoO_xShows lower catalytic activity andhigh selectivity, and therefore, there is an increasing effort to develop non-noble metal catalysts supported on heteroatom-doped carbon for catalytic hydrogenation. However, most of the reported catalysts have poor catalytic activity, far lower than commercially available noble metal catalysts (e.g., Pd-Pt/C: 90-200 deg.C, 6bar H)₂；Pd/Al₂O₃:250～350℃，7bar H₂Etc.), harsh reaction conditions are also often required.

Currently, some studies have developed a porous carbon doped with N (i.e., Co-N) by pyrolyzing a cobalt phthalocyanine/silica composite followed by acid treatment_xCo-N with/C-800-AT) as carrier_xA catalyst. As active centre, Co-N_xIs highly efficient and can be realized under mild conditions (110 ℃, 3.5bar H)₂) Selective hydrogenation of nitro compounds, even at 40 ℃ and 1bar H₂The following is also possible. Unfortunately, precursors are expensive and the preparation process is complicated, which makes scale-up difficult both for production and practical use. Therefore, the prior art urgently needs a non-noble metal catalyst with high activity and low cost, and can catalyze the hydrogenation of nitro compounds under mild reaction conditions.

Disclosure of Invention

Aiming at the defects of the hydrogenation catalyst in the prior art, the invention aims to provide a Co-nitrogen doped porous carbon loaded Co for hydrogenation of nitro compounds, which has high active site exposure, high efficiency and good selectivity_xZnS catalytic material (CoN)_x-Co_xZnS @ NPCs) that can effect hydrogenation of nitro compounds under mild conditions, e.g., at temperature<Hydrogen pressure at 100 deg.C<The high-efficiency hydrogenation of the nitro compound is realized under the condition of 5bar, and particularly, the hydrogenation effect is better under the room temperature condition.

The second purpose of the present invention is to provide a method for preparing the CoN, which is simple in operation, environment-friendly and low in cost_x-Co_xA method for preparing a ZnS @ NPCs non-noble metal catalytic material.

It is a third object of the present invention to provide CoN_x-Co_xApplication of ZnS @ NPCs catalyst to nitrateThe selective hydrogenation method of the base compound has the advantages of good selectivity, high hydrogenation efficiency, low use cost and the like.

In order to realize the technical purpose, the invention provides nitrogen-cobalt Co-doped porous carbon loaded Co_xThe preparation method of the ZnS catalytic material comprises the steps of dissolving and dispersing zinc salt, cobalt salt and sulfur-containing protein into water, carrying out freeze drying and pyrolysis, and carrying out acid washing on a pyrolysis product to obtain the ZnS catalytic material.

The invention mainly uses protein-metal ion (Co)²⁺/Zn²⁺) Performing pyrolysis on the complex, and performing acid treatment to obtain Co-nitrogen doped porous carbon loaded Co_xZnS catalyst (CoN)_x-Co_xZnS@NPCs)。

The common carbon supported catalyst in the prior art has poor hydrogenation performance mainly due to low activity of an active center and low exposure degree of the active center, and is embedded_xDoped porous carbon, and CoN with high hydrogenation activity imparted by sulfur-fixed metal ions in sulfur-containing protein_xAnd Co_xZnS active center, thereby obtaining the catalytic material with high hydrogenation activity.

Preferably, the zinc salt is a common easily soluble zinc salt, specifically at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc bromide and zinc acetate.

Preferably, the cobalt salt is a common soluble cobalt salt, and specifically, the cobalt salt is at least one of cobalt chloride, cobalt bromide, cobalt nitrate and cobalt sulfate.

Preferably, the sulfur-containing protein is a common sulfur-containing protein, such as at least one of bovine serum albumin, ovalbumin, casein, and keratin.

In a preferable scheme, the mass ratio of the cobalt salt to the sulfur-containing protein is 0.5: 10-3: 10; most preferably 1.75: 10.

In a preferred embodiment, the mass ratio of the zinc salt to the sulfur-containing protein is 0.5:1 to 1.5:1, and most preferably 1: 1.

In a preferred embodiment, the pyrolysis conditions are: and pyrolyzing for 1-3 h at 400-1200 ℃ in a protective atmosphere. The preferred pyrolysis temperature is 700-950 ℃. The protective atmosphere may be nitrogen or a common inert gas.

In a preferred embodiment, the acid washing conditions are as follows: and (3) placing the pyrolysis product in 0.5-1.5M HCl aqueous solution, and stirring for 4-12 h at the temperature of 40-120 ℃. Most preferably, the pyrolysis product is placed in 1M aqueous HCl and stirred for 8h at a temperature of 80 ℃.

The invention provides nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material obtained by any one of the above-mentioned preparation methods.

In a preferred embodiment, the nitrogen-cobalt Co-doped porous carbon supports Co_xThe ZnS catalyst has a loose porous structure, micropores with the aperture of 1-2 nm and mesopores with the aperture of 2-14 nm, and the specific surface area is 800m²g^-1～1200m²g^-1Total pore volume of 0.40cm³g^-1～0.90cm³g^-1。

The invention also provides nitrogen-cobalt Co-doped porous carbon loaded Co_xThe application of the ZnS catalytic material in catalyzing the hydrogenation reaction of nitro compounds.

In a preferred scheme, nitrogen-containing cobalt Co-doped porous carbon is loaded with Co_xIntroducing hydrogen into a mixed solution system of the ZnS catalytic material, sulfide and nitro compound in alcohol and water to perform catalytic hydrogenation reaction. Wherein the sulfide may be Na₂S, thioethylene glycol or KSCN, the sulfide primarily serving to donate H₂S。

In a preferred embodiment, the conditions of the catalytic hydrogenation reaction are as follows: h₂The pressure is less than or equal to 5bar, the temperature is less than or equal to 100 ℃, and the time is 1.5-4.5 h. Better hydrogenation effect can be achieved under the condition of room temperature and the hydrogen pressure below 5 bar.

In a preferred embodiment, the catalytic hydrogenation reaction may be selected from the group consisting of EtOH, MeOH, and MeOH/H₂And (4) O solvent.

CoN provided by the invention_x-Co_xThe preparation method of the ZnS @ NPCs catalytic material specifically comprises the following steps:

10g of bovine serum albumin was dissolved in 20mL of redistilled water, and then 1.75g of CoCl was added₂·6H₂O is mixed in the solution and stirred magnetically for 1 h. Then dissolving zinc chloride in a certain mass ratio in water. The two solutions were mixed and stored for 1h at room temperature under magnetic stirring. The resulting pink protein complex was freeze-dried for 24 hours to give a pale blue solid. The mass ratio of the zinc salt to the bovine serum albumin is adjusted within the range of 0.5-1.5: 1. The lyophilized solid is then ground to a powder and then incubated at 5 deg.C for a period of min^-1The powder was pyrolyzed to 800 ℃ and flowing nitrogen (40mL min) at 800 ℃^-1) Keeping the atmosphere for 2h, and then naturally cooling to room temperature. The obtained solid is automatically ground into carbon powder by agate mortar, then added into 1M HCl aqueous solution, stirred vigorously for 8h at 80 ℃, the obtained black dispersion is filtered on an organic microporous membrane, washed by deionized water until the pH is neutral, and then absolute ethyl alcohol is used. The filtered solid was dried overnight in a vacuum drying chamber at 40 ℃. To obtain CoN_x-Co_xZnS@NPCs。

Compared with the prior art, the technical scheme of the invention brings effective results that:

(1) CoN provided by the invention_x-Co_xThe ZnS @ NPCs catalyst has a layered porous structure, the introduction of Zn is favorable for dispersing nano particles, the well-dispersed nano particles are contacted and finally removed by acid to form a uniformly-distributed pore structure, and the formation of a large number of micropores and mesopores is favorable for mass transfer in the reaction process, so that the hydrogenation efficiency of the catalytic material can be improved.

(2) CoN provided by the invention_x-Co_xThe ZnS @ NPCs catalyst has good dispersibility and high-efficiency Co sites, the catalytic activity of the catalyst is greatly improved, and acid treatment can remove large nanoparticles and cause more pores, so that more active sites are exposed, and the catalyst is favorable for the dynamics of the catalyst.

(3) CoN provided by the invention_x-Co_xThe ZnS @ NPCs catalyst has the ability to combat CO and inorganic/organic sulfur poisoning. High activity is maintained even in the presence of high concentrations of CO or S-containing species, in contrast to commercial Pd/C in phaseThe activity is extremely low under the same condition.

(4) CoN provided by the invention_x-Co_xThe ZnS @ NPCs catalyst has a wide range and good universality when being used for hydrogenation of nitro compounds, particularly, nitrobenzene derivatives can be subjected to high-selectivity hydrogenation, and substrates such as alkyl substituted compounds, halogenated compounds, fused ring compounds, unsaturated compounds and the like can be subjected to catalytic hydrogenation to generate corresponding amine compounds with high conversion rate and selectivity.

(5) CoN provided by the invention_x-Co_xThe ZnS @ NPCs catalyst has stronger durability, the porosity and the structure of the catalyst are not obviously changed after eight times of operation, the dispersity of Co, Zn, C, N and S is good, and the higher catalytic activity is still maintained.

(6) CoN provided by the invention_x-Co_xCompared with a noble metal catalyst, the ZnS @ NPCs catalyst has the advantages of mild catalytic reaction conditions, low use cost, wide application range and strong toxicity resistance.

(7) CoN provided by the invention_x-Co_xThe preparation method of the ZnS @ NPCs catalyst is simple, easy to operate, environment-friendly and applicable to industrialization, and adopts nontoxic and cheap raw materials, does not need large-scale complex devices.

Drawings

FIG. 1 shows NPC, Co @ NPC, ZnS @ NPC and CoN prepared in examples 1, 2, 3 and 4 of the present invention_x-Co_xX-ray diffraction (XRD) pattern of ZnS @ NPC-Y catalyst: CoN_x-Co_xIn ZnS @ NPC-Y catalyst, green curve: CoN_x-Co_xZnS @ NPC-0.5; purple curve: CoN_x-CoxZnS @ NPC-1; yellow curve: CoN_x-Co_xZnS@NPC-3。

FIG. 2 shows Co @ NPC, ZnS @ NPC, CoN prepared in examples 1, 2, 3 and 4 of the present invention_x-Co_xZnS@NPC-0.5，CoN_x-Co_xZnS @ NPC-1 and CoN_x-Co_xRaman spectral images of ZnS @ NPC-3 catalyst.

FIG. 3 is an image of a Transmission Electron Microscope (TEM) and a high transmission electron microscope (HRTEM) of Co @ NPC prepared in example 1 of the present invention.

FIG. 4 shows CoN prepared in example 4 of the present invention_x-Co_xThe conversion and yield distribution diagram of the ZnS @ NPC-3 catalyst for catalyzing and hydrogenating nitrobenzene is as follows: nitro compound 0.25mmol, catalyst 20mg, solvent (water/methanol ═ 1:1)6ml, 90 ℃, 3H, H ₂5 bar; the conversion and selectivity of the reaction (in parentheses) were determined by high performance liquid chromatography.

FIG. 5 shows CoN prepared in example 4 of the present invention_x-Co_xRecoverability profile of ZnS @ NPC-3 catalyst.

FIG. 6 shows CoN prepared in example 4_x-Co_xThe conversion rate and the selectivity of a ZnS @ NPC-3 catalyst for catalytic hydrogenation of a nitro compound into a corresponding amine compound; reaction conditions are as follows: nitro compound 0.25mmol, catalyst 20mg, solvent (water/methanol ═ 1:1)6ml, 90 ℃, 3H, H ₂5 bar; the conversion and selectivity of the reaction (in parentheses) were determined by high performance liquid chromatography.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples, but the scope of the present invention is not limited to the following examples.

Example 1

Preparation of Co @ NPC: 10g of bovine serum albumin was dissolved in 20mL of redistilled water, and then 1.75g of CoCl was added₂·6H₂O is mixed in the solution and stirred magnetically for 1 h. The resulting protein complex was freeze-dried for 24 hours to give a solid. The lyophilized solid is then ground to a powder and then incubated at 5 deg.C for a period of min^-1The powder was pyrolyzed to 800 ℃ and flowing nitrogen (40mL min) at 800 ℃^-1) Keeping the atmosphere for 2h, and then naturally cooling to room temperature. The obtained solid is automatically ground into carbon powder by agate mortar, then added into 1M HCl aqueous solution, stirred vigorously for 8h at 80 ℃, the obtained black dispersion is filtered on an organic microporous membrane, washed by deionized water until the pH is neutral, and then absolute ethyl alcohol is used. The filtered solid was dried overnight in a vacuum drying chamber at 40 ℃.

Example 2

CoN_x-Co_xPreparation of ZnS @ NPC-0.5: 10g of bovine serum albumin was dissolved in 20mL of redistilled water, and then 1.75g of CoCl was added₂·6H₂O is mixed in the solution and stirred magnetically for 1 h. Then dissolving zinc chloride in a certain mass ratio in water. The two solutions were mixed and stored for 1h at room temperature under magnetic stirring. The resulting pink protein complex was freeze-dried for 24 hours to give a pale blue solid. The mass ratio of the zinc salt to the bovine serum albumin is 0.5/1. The lyophilized solid is then ground to a powder and then incubated at 5 deg.C for a period of min^-1The powder was pyrolyzed to 800 ℃ and flowing nitrogen (40mL min) at 800 ℃^-1) Keeping the atmosphere for 2h, and then naturally cooling to room temperature. The obtained solid is automatically ground into carbon powder by agate mortar, then added into 1M HCl aqueous solution, stirred vigorously for 8h at 80 ℃, the obtained black dispersion is filtered on an organic microporous membrane, washed by deionized water until the pH is neutral, and then absolute ethyl alcohol is used. The filtered solid was dried overnight in a vacuum drying chamber at 40 ℃.

Example 3

CoN_x-Co_xPreparation of ZnS @ NPC-1: 10g of bovine serum albumin was dissolved in 20mL of redistilled water, and then 1.75g of CoCl was added₂·6H₂O is mixed in the solution and stirred magnetically for 1 h. Then dissolving zinc chloride in a certain mass ratio in water. The two solutions were mixed and stored for 1h at room temperature under magnetic stirring. The resulting pink protein complex was freeze-dried for 24 hours to give a pale blue solid. The mass ratio of the zinc salt to the bovine serum albumin was 1/1. The lyophilized solid is then ground to a powder and then incubated at 5 deg.C for a period of min^-1The powder was pyrolyzed to 800 ℃ and flowing nitrogen (40mL min) at 800 ℃^-1) Keeping the atmosphere for 2h, and then naturally cooling to room temperature. The obtained solid is automatically ground into carbon powder by agate mortar, then added into 1M HCl aqueous solution, stirred vigorously for 8h at 80 ℃, the obtained black dispersion is filtered on an organic microporous membrane, washed by deionized water until the pH is neutral, and then absolute ethyl alcohol is used. The filtered solid was dried overnight in a vacuum drying chamber at 40 ℃.

Example 4

CoN_x-Co_xPreparation of ZnS @ NPC-3: 10g of bovine serum albumin was dissolved in 20mL of redistilled water, and then 1.75g of CoCl was added₂·6H₂O is mixed in the solution and stirred magnetically for 1 h. Then dissolving zinc chloride in a certain mass ratio in water. The two solutions were mixed and stored for 1h at room temperature under magnetic stirring. The resulting pink protein complex was freeze-dried for 24 hours to give a pale blue solid. The mass ratio of the zinc salt to the bovine serum albumin was 3/1. The lyophilized solid is then ground to a powder and then incubated at 5 deg.C for a period of min^-1The powder was pyrolyzed to 800 ℃ and flowing nitrogen (40mL min) at 800 ℃^-1) Keeping the atmosphere for 2h, and then naturally cooling to room temperature. The obtained solid is automatically ground into carbon powder by agate mortar, then added into 1M HCl aqueous solution, stirred vigorously for 8h at 80 ℃, the obtained black dispersion is filtered on an organic microporous membrane, washed by deionized water until the pH is neutral, and then absolute ethyl alcohol is used. The filtered solid was dried overnight in a vacuum drying chamber at 40 ℃.

Example 5

CoN prepared in example 4_x-Co_xThe ZnS @ NPC-3 catalyst can be used for hydrogenation of nitro compounds. Nitrobenzene (0.25mmol), catalyst CoN, was charged to a 25mL stainless steel autoclave filled with a magnetically stirred polytetrafluoroethylene liner_x-Co_xZnS @ NPC-3(20mg), 5mL of a mixture of water and methanol (volume ratio 1: 1). Subsequently, the autoclave was purged 5 times with hydrogen and finally pressurized to 5bar, placed in a stirrer hot plate apparatus, preheated at 90 ℃ and after 3 hours, the remaining gas was carefully released and the autoclave was naturally cooled at room temperature. The reaction mixture was filtered on a nylon syringe filter (pore size 0.22 μm), the catalyst was separated, and the filtrate was extracted with ethyl acetate. The ethyl acetate phase was concentrated under reduced pressure and the reaction was analyzed by high performance liquid chromatography.

Example 6

CoN prepared in example 4_x-Co_xThe ZnS @ NPC-3 catalyst can be used for catalytically hydrogenating nitro compounds into corresponding amine compounds with high conversion rate and selectivity, including alkyl substituted compounds and halogenated compoundsA condensed ring compound, an unsaturated compound, etc. The specific reaction conditions are as follows: nitro compound 0.25mmol, catalyst 20mg, solvent (water/methanol ═ 1:1)6ml, 90 ℃, 3H, H ₂5 bar; the procedure is as in example 5. For normal substrates including ester, amide, hydroxyl, alkyl, carboxyl, ether and thioether substituted nitro compounds, conversion rates approach 100% and selectivity to the corresponding amine compound is between 99.0% and 99.9%; for the hydrogenation of halogenated nitro compounds, the conversion rate is up to 100%, the selectivity is up to 99.9%, and dehalogenation is not needed; for nitro compounds containing other unsaturated compounds (such as aldehydes, cyano, alkynes and ketones), the nitro group is selectively reduced to the corresponding amino compound (conversion up to 100%, selectivity between 99.2% and 99.9%) without affecting the unsaturated group. In addition, for substrates containing fused rings, the corresponding products can be obtained with high conversion and high selectivity (up to 100% conversion, with selectivity between 98.8% and 99.9%). Finally, for some substrates of relatively large molecular volume, they can be efficiently hydrogenated to amine products (up to 100% conversion and up to 99.9% selectivity) due to their unique hierarchical pore structure, enabling rapid mass transfer. The selectivity and yield of the amine product converted from the specific nitro compound are shown in fig. 5.

NPC, Co @ NPC, ZnS @ NPC, CoN prepared in examples 1, 2, 3 and 4 as shown in the diffraction Pattern (XRD) of FIG. 1_x-Co_xIn the ZnS @ NPC-Y catalyst, except NPC, a 25.2-degree peak can be detected in the XRD patterns of all samples, and the (002) surface of graphite carbon is indexed. In the XRD pattern of Co @ NPC, peaks at 44.3 ℃ and 51.9 ℃ were observed, which were ascribed to the (111) and (200) crystallographic planes of metallic Co. All CoN_x-Co_xThe ZnS @ NPC-Y samples all have similar XRD lines, and the peaks at 28.57 DEG, 33.12 DEG, 47.53 DEG, 56.40 DEG, 69.15 DEG and 76.78 DEG can all be assigned to Zn_0.975Co_0.025The (111), (200), (220), (331) and (400) crystal planes of S. In contrast, ZnS @ NPC has the same CoN_x-Co_xZnS @ NPC-Y has a similar XRD line, but the peaks show a slight blue shift, which is very consistent with the PDF card of ZnS. Furthermore, in CoN_x-Co_xThe x-ray diffraction pattern of ZnS @ NPC-Y showed no Co presence, indicating that these samples were not acid treated with large Co particles.

As shown in the Raman spectrum of FIG. 2, Co @ NPC, ZnS @ NPC, CoN prepared in examples 1, 2, 3 and 4_x-Co_xZnS@NPC-0.5,CoN_x-Co_xZnS @ NPC-1 and CoN_x-Co_xThe Raman spectra of the ZnS @ NPC-3 catalyst all showed two distinct peaks, the D band (about 1340 cm)^–1) And G belt (about 1587 cm)^–1) Due to the disordered and graphitic nature of the carbon structure, respectively. Intensity ratio of D/G (i.e. I)_D/I_G) The degree of defect of the carbon matrix can be characterized. Apparently, CoN_x-Co_xZnS@NPC-0.5,CoN_x-Co_xZnS @ NPC-1 and CoN_x-Co_xZnS @ NPC-2I_D/I_GThe values are higher than Co @ NPC (1.00, 0.99, 1.01 vs. 0.96). With the increase of Zn content in the precursor, I_D/I_GSlightly increased. This indicates that high Zn content favors the crushing process, leading to more defective structures.

Embodiment 2-4 preparation of nitrogen-cobalt Co-doped porous carbon loaded Co_xThe ZnS catalyst has a loose porous structure and simultaneously has micropores with the aperture of 1-2 nm and mesopores with the aperture of 2-14 nm. And, the specific surface area (S) of the sample_BET) And total volume (V)_total) The sequence of (A) is as follows: CoN_x-Co_xZnS@NPC-3(1109.8m²g^-1，0.81cm³g^-1)>CoN_x-Co_xZnS@NPC-1(951.1m²g^-1，0.61cm³g^-1)>CoN_x-Co_xZnS@NPC-0.5(810.5m²g^-1，0.48cm³g^-1). While sample Co @ NPC (240.5 m)²g^-1，0.15cm³g^-1)。

The Co @ NPC catalyst prepared in this example 1 (i.e., in the absence of Zn) is shown in the Transmission Electron Microscope (TEM) and high transmission electron microscope (HRTEM) images of FIG. 3²⁺In the case of (a) shows a dense structure without a significant pore structure. Furthermore, in Co @ NPC, it can be observed that the catalyst is composed of a carbon matrixEncapsulated nanoparticles of size 2nm indicate that acid treatment cannot completely remove Co particles because they tend to aggregate and intercalate into the dense carbon matrix.

CoN prepared in example 4, as shown by the transformation and yield profiles of FIG. 4_x-Co_xWhen the ZnS @ NPC-3 catalyst is used for catalyzing and hydrogenating nitrobenzene, the yield of aminobenzene is increased along with the prolonging of reaction time, and the yield of phenylhydroxylamine in the catalytic hydrogenation reaction is very small. Furthermore, during the catalytic hydrogenation only phenylhydroxylamine was detected and no azobenzene was found, indicating that the catalytic hydrogenation follows a "direct route" mechanism rather than a condensation route.

As shown in the recoverable chart of FIG. 5, CoN produced in this example 4_x-Co_xThe ZnS @ NPC-3 catalyst still keeps higher catalytic activity (C: 99.7%, S: 99.1%) after eight runs, and embodies CoN_x-Co_xThe durability of the ZnS @ NPC-3 catalyst in hydrogenation reactions.

By way of example, the above examples demonstrate a novel cobalt nitride Co-doped porous carbon supported Co_xZnS catalyst (CoN)_x-Co_xZnS @ NPCs) and its use for the selective hydrogenation of nitro compounds under mild conditions. The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all equivalent changes and modifications made in the claims of the present invention should be covered by the present invention, and the protection scope of the present invention is as shown in the claims of the present application.

Claims

1. Nitrogen-cobalt Co-doped porous carbon loaded Co_xThe preparation method of the ZnS catalytic material is characterized by comprising the following steps: dissolving and dispersing zinc salt, cobalt salt and sulfur-containing protein into water, freeze-drying and pyrolyzing, and acid-washing a pyrolysis product to obtain the catalyst.

2. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 1_xThe preparation method of the ZnS catalytic material is characterized by comprising the following steps:

the zinc salt is at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc bromide and zinc acetate.

The cobalt salt is at least one of cobalt chloride, cobalt bromide, cobalt nitrate and cobalt sulfate;

the sulfur-containing protein is at least one of bovine serum albumin, ovalbumin, casein and keratin.

3. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 1 or 2_xThe preparation method of the ZnS catalytic material is characterized by comprising the following steps:

the mass ratio of the cobalt salt to the sulfur-containing protein is 0.5-3: 10;

the mass ratio of the zinc salt to the sulfur-containing protein is 0.5: 1-1.5: 1.

4. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 1 or 2_xThe preparation method of the ZnS catalytic material is characterized by comprising the following steps: the pyrolysis conditions are as follows: and pyrolyzing for 1-3 h at 400-1200 ℃ in a protective atmosphere.

5. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 1_xThe preparation method of the ZnS catalytic material is characterized by comprising the following steps: the pickling conditions are as follows: and (3) placing the pyrolysis product in 0.5-1.5M HCl aqueous solution, and stirring for 4-12 h at the temperature of 40-120 ℃.

6. Nitrogen-cobalt Co-doped porous carbon loaded Co_xZnS catalytic material, characterized in that: the preparation method of any one of claims 1 to 5.

7. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 6_xZnS catalytic material, characterized in that: the nitrogen-cobalt Co-doped porous carbon loaded Co_xThe ZnS catalyst has a loose porous structure, micropores with the aperture of 1-2 nm and mesopores with the aperture of 2-14 nm, and the specific surface area is 800m²g^-1～1200m²g^-1Total pore volumeIs 0.40cm³g^-1～0.90cm³g^-1。

8. The nitrogen-cobalt Co-doped porous carbon loaded Co of claim 6 or 7_xThe application of the ZnS catalytic material is characterized in that: the method is applied to catalyzing hydrogenation reaction of nitro compounds.

9. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 8_xThe application of the ZnS catalytic material is characterized in that: co loaded with nitrogen-containing cobalt Co-doped porous carbon_xIntroducing hydrogen into a mixed solution system of the ZnS catalytic material, sulfide and nitro compound in alcohol and water to perform catalytic hydrogenation reaction.

10. The nitrogen-cobalt Co-doped porous carbon loaded Co according to claim 9_xThe application of the ZnS catalytic material is characterized in that: the conditions of the catalytic hydrogenation reaction are as follows: h₂The pressure is less than or equal to 5bar, the temperature is less than or equal to 100 ℃, and the time is 1.5-4.5 h.