阅读说明：本技术 一种原位硫掺杂介孔碳负载钯金属催化剂及其制备方法与应用 (In-situ sulfur-doped mesoporous carbon-supported palladium metal catalyst and preparation method and application thereof ) 是由 张群峰 周媛 张超杰 马磊 卢春山 丰枫 吕井辉 李小年 于 2019-08-30 设计创作，主要内容包括：本发明提供了一种原位硫掺杂介孔碳负载钯金属催化剂及其制备方法与应用,本发明采用直接水热碳化与煅烧进一步碳化的方法直接获得所需载体材料,使得硫能掺入到碳材料的骨架,以更稳定的形式存在；硫掺杂活性炭负载贵金属催化剂中,掺杂所产生的大量缺陷更有利于钯金属纳米粒子与载体的稳定结合,硫与金属之间的强烈的相互作用保证了催化剂的高度稳定性,使得金属纳米颗粒在加氢反应过程中不易团聚和流失,有利于延长催化剂寿命；本发明所述催化剂在卤代硝基苯的选择性加氢反应中,可使得卤代硝基苯完全转化,卤代苯胺选择性可达99.9％,并且使用条件温和、稳定性好,催化剂用量少,催化剂使用寿命长。(the invention provides an in-situ sulfur-doped mesoporous carbon-supported palladium metal catalyst, and a preparation method and application thereof, wherein the required carrier material is directly obtained by a method of direct hydrothermal carbonization and calcination for further carbonization, so that sulfur can be doped into a framework of a carbon material and exists in a more stable form; in the sulfur-doped active carbon supported noble metal catalyst, a large number of defects generated by doping are more beneficial to the stable combination of palladium metal nanoparticles and a carrier, and the strong interaction between sulfur and metal ensures the high stability of the catalyst, so that the metal nanoparticles are not easy to agglomerate and run off in the hydrogenation reaction process, and the service life of the catalyst is prolonged; the catalyst of the invention can completely convert the halogenated nitrobenzene in the selective hydrogenation reaction of the halogenated nitrobenzene, the selectivity of the halogenated aniline can reach 99.9 percent, and the catalyst has mild use condition, good stability, less catalyst consumption and long service life.)

1. An in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst is characterized by being prepared by the following method:

(1) Preparing sulfur-doped activated carbon: dissolving glucose in deionized water, adding a sulfur-containing precursor, carrying out hydrothermal reaction at 180-300 ℃ for 20-50 h, then cooling to room temperature, filtering, carrying out vacuum drying on a filter cake at 40-80 ℃ for 8-15 h to obtain a primarily carbonized in-situ doped carbon material, and then heating to 400-800 ℃ in an inert gas atmosphere, and roasting for 2-8 h to obtain an in-situ sulfur doped carbon material;

The sulfur-containing precursor is KHSO₃、NaHSO₃One or a mixture of two of them in any proportion;

The mass ratio of the sulfur-containing precursor to glucose in terms of sulfur element is 0.02-0.15: 1;

(2) Loading of noble metal: mixing the obtained in-situ sulfur-doped carbon material with a noble metal precursor aqueous solution, carrying out ultrasonic treatment for 2-10 min to obtain a uniform dispersion system, and drying at 40-80 ℃ for 8-15 h to obtain the in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst;

The noble metal precursor is chloropalladate, sodium chloropalladate or palladium acetate.

2. The in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst of claim 1, wherein in the step (1), the mass ratio of the sulfur-containing precursor to glucose in terms of elemental sulfur is 0.05-0.1: 1.

3. The in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst of claim 1, wherein in the step (2), the concentration of the noble metal precursor aqueous solution is 0.001-0.01 g/mL.

4. The in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst of claim 1, wherein the noble metal loading in the resulting catalyst is 0.02 to 1 wt% based on the mass of the support.

5. The use of the in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst of claim 1 in a reaction for preparing halogenated aromatic amines by liquid-phase catalytic hydrogenation of halogenated aromatic nitro compounds.

6. The application of claim 5, wherein the method of applying is:

Before reaction, the catalyst is firstly added in H₂reducing for 1-4 h at 50-200 ℃ in the atmosphere, mixing the reduced catalyst with halogenated aromatic nitro compound (I) and ethanol, stirring and reacting for 4-6 h at the temperature of 80-100 ℃ and the hydrogen pressure of 0.5-3 MPa, and then carrying out post-treatment on the reaction liquid to obtain halogenated aromatic amine (II);

The mass ratio of the halogenated aromatic nitro compound (I) to the catalyst is 100: 0.1 to 3;

The post-treatment method comprises the following steps: after the reaction is finished, cooling the temperature of the reaction liquid to room temperature, filtering to obtain a filter cake which is the catalyst, and drying and recycling in vacuum for reuse; rectifying or distilling the filtrate to obtain a target product;

In the formula (I) or (II),

R₁、R₂、R₃、R₄、R₅Each independently is: -H, -CH₃、-CH₂CH₃、-OH、-NH₂、-OCH₃、-COOCH₃、-NHCH₂CH₃or-N (CH)₃)₂And R is₁、R₂、R₃、R₄、R₅Is halogen, said halogen being-F, -Cl or-Br.

(I) technical field

The invention relates to an in-situ sulfur-doped carbon material-supported palladium catalyst, a preparation method thereof and application thereof in a liquid phase hydrogenation reaction of halogenated nitrobenzene.

(II) background of the invention

The halogenated aniline is an extremely important organic intermediate and has wide application in the fields of medicines, dyes and the like. The selective hydrogenation of halogenated nitrobenzene is the main process for the preparation of halogenated anilines. The traditional preparation method of halogenated aniline comprises a metal reduction method, an electrolytic reduction method, a sodium sulfide reduction method, a hydrazine hydrate reduction method and the like. Because the traditional preparation methods have the defects of more three wastes, large energy consumption and unsatisfactory product quality, the catalytic hydrogenation process which is relatively advanced and more environment-friendly in recent years is widely concerned. The supported noble metal Pd catalyst has the advantages of good catalytic activity, environmental friendliness, simple preparation process and relatively low price, and represents a great advantage in industrial production. However, the traditional Pd/C catalyst has the problems of poor selectivity, poor stability and the like in the reaction of preparing the halogenated aromatic amine by selectively hydrogenating the halogenated aromatic nitro compound. Therefore, the method for solving the problems of over-high activity, poor selectivity, easy loss or agglomeration of the Pd/C catalyst has important significance for the industrial production of the halogenated arylamine.

Based on the background, the invention provides a method for in-situ synthesis of a sulfur-doped carbon material and loading of palladium metal through hydrothermal carbonization and calcination to prepare the in-situ sulfur-doped carbon material loaded noble metal catalyst. Due to the interaction between the incorporated sulfur atoms and the metal nanoparticles, the metal is not only better dispersed, but also can be stably attached to the support surface. The catalyst can reach the selectivity of more than or equal to 99.9 percent in the reaction of preparing the halogenated aromatic amine by selectively hydrogenating the halogenated aromatic nitro compound while keeping the complete conversion of the halogenated aromatic nitro compound.

Disclosure of the invention

The invention aims to provide an in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst, a preparation method thereof and application thereof in selective hydrogenation reaction of halogenated nitrobenzene. The preparation method is simple and convenient to operate, green and environment-friendly, and the palladium can be uniformly anchored on the surface of the sulfur-doped carbon material. The prepared catalyst can efficiently convert the halogenated nitrobenzene into the halogenated aniline, has high activity and excellent selectivity, and can effectively perform dehalogenation side reaction. In the application experiment, the catalyst shows good stability and can be recycled for multiple times.

The technical scheme of the invention is as follows:

An in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst is prepared by the following method:

(1) preparing sulfur-doped activated carbon: dissolving glucose in deionized water, adding a sulfur-containing precursor, carrying out hydrothermal reaction at 180-300 ℃ for 20-50 h, then cooling to room temperature (20-30 ℃), filtering, carrying out vacuum drying on a filter cake at 40-80 ℃ for 8-15 h to obtain a primarily carbonized in-situ doped carbon material, and then carrying out in an inert gas (N)₂He or Ar), heating to 400-800 ℃, and roasting for 2-8 h to obtain an in-situ sulfur-doped carbon material;

the sulfur-containing precursor is KHSO₃、NaHSO₃One or a mixture of two of them in any proportion;

the mass ratio of the sulfur-containing precursor to glucose in terms of sulfur element is 0.02-0.15: 1, preferably 0.05 to 0.1: 1;

(2) loading of noble metal: mixing the obtained in-situ sulfur-doped carbon material with a noble metal precursor aqueous solution, carrying out ultrasonic treatment (ultrasonic power is 150W and ultrasonic frequency is 28KHz) for 2-10 min to obtain a uniform dispersion system, and drying at 40-80 ℃ for 8-15 h to obtain the in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst;

the concentration of the noble metal precursor aqueous solution is 0.001-0.01 g/mL;

The noble metal precursor is chloropalladic acid, sodium chloropalladate or palladium acetate, and preferably chloropalladic acid;

In the catalyst, the loading amount of the noble metal is 0.02-1 wt%, preferably 0.05-0.1 wt% based on the mass of the carrier;

In the present invention, the noble metal can be considered as the whole load, and the amount of the noble metal precursor to be added can be selected by those skilled in the art according to the required load amount.

The in-situ sulfur-doped mesoporous carbon supported palladium metal catalyst can be applied to the reaction of preparing halogenated arylamine by liquid-phase catalytic hydrogenation of halogenated aromatic nitro compounds.

Specifically, the application method comprises the following steps:

Before reaction, the catalyst is firstly added in H₂Reducing for 1-4 h at 50-200 ℃ in the atmosphere, mixing the reduced catalyst with halogenated aromatic nitro compound (I) and ethanol, stirring and reacting for 4-6 h at the temperature of 80-100 ℃ and the hydrogen pressure of 0.5-3 MPa, and then carrying out post-treatment on the reaction liquid to obtain halogenated aromatic amine (II);

the mass ratio of the halogenated aromatic nitro compound (I) to the catalyst is 100: 0.1 to 3, preferably 100: 0.2 to 1.5;

The post-treatment method comprises the following steps: after the reaction is finished, cooling the temperature of the reaction liquid to room temperature, filtering to obtain a filter cake which is the catalyst, and drying and recycling in vacuum for reuse; rectifying or distilling the filtrate to obtain a target product;

in the formula (I) or (II),

R₁、R₂、R₃、R₄、R₅each independently is: -H, -CH₃、-CH₂CH₃、-OH、-NH₂、-OCH₃、-COOCH₃、-NHCH₂CH₃or-N (CH)₃)₂And R is₁、R₂、R₃、R₄、R₅Is halogen, said halogen being-F, -Cl or-Br.

Compared with the prior art, the invention has the following advantages:

(1) the preparation method of the in-situ sulfur-doped carbon material supported palladium catalyst adopts a method of direct hydrothermal carbonization and calcination for further carbonization, and the method can directly obtain the required carrier material, so that sulfur can be doped into the framework of the carbon material and exists in a more stable form;

(2) The ultrasonic auxiliary method can realize the high dispersion of the noble metal palladium

(3) In the sulfur-doped active carbon supported noble metal catalyst, a large number of defects generated by doping are more beneficial to the stable combination of palladium metal nanoparticles and a carrier, and the strong interaction between sulfur and metal ensures the high stability of the catalyst, so that the metal nanoparticles are not easy to agglomerate and run off in the hydrogenation reaction process, and the service life of the catalyst is prolonged;

(4) The catalyst can completely convert the halogenated nitrobenzene in the selective hydrogenation reaction of the halogenated nitrobenzene, and the selectivity of the halogenated aniline can reach 99.9 percent;

(5) The catalyst of the invention has mild use condition, good stability, less catalyst consumption and long service life.

(IV) detailed description of the preferred embodiments

the present invention is further illustrated by the following specific examples, but the scope of the invention is not limited thereto.