CN115532265A

CN115532265A - Halloysite-loaded nickel-based nano catalyst and preparation method and application thereof

Info

Publication number: CN115532265A
Application number: CN202211156447.9A
Authority: CN
Inventors: 白国义; 李文炅; 吴清瑶
Original assignee: Hebei University
Current assignee: Hebei University
Priority date: 2022-09-22
Filing date: 2022-09-22
Publication date: 2022-12-30
Anticipated expiration: 2042-09-22
Also published as: CN115532265B

Abstract

The invention provides a halloysite-loaded nickel-based nano catalyst and a preparation method and application thereof. The catalyst has magnetism, active component Ni is dispersed in the catalyst, and the particle size of the active component Ni is less than 1nm. The catalyst provided by the invention has excellent activity and can be compared favorably with a noble metal catalyst. In the reaction of hydrogenating phthalic acid ester to cyclohexane diformate, the conversion rate of dioctyl phthalate is 99 percent, and the selectivity of 1, 2-dioctyl cyclohexane diformate is also 99 percent; and because the catalyst has magnetism, after each reaction, the catalyst can be applied in subsequent reactions through simple magnetic separation and cleaning by an external magnetic field. The catalyst can be continuously used for 9 times, the catalytic performance is kept unchanged, and the catalyst has excellent recycling performance and good stability. The preparation method is simple, low in cost, good in repeatability, capable of being recycled for multiple times, and wide in industrial application prospect.

Description

Halloysite-loaded nickel-based nano catalyst and preparation method and application thereof

Technical Field

The invention relates to the field of catalytic materials, in particular to a halloysite-loaded nickel-based nano catalyst and a preparation method and application thereof.

Background

The phthalate compound is a plasticizer which can greatly improve the flexibility and durability of plastic products; the usage amount of the phthalate ester compound is huge, and the usage amount in only 2014 year reaches 840 ten thousand tons, which accounts for 70 percent of the global usage amount. However, phthalate esters are also one of the main chemicals that destroy endocrine systems, resulting in cancer, obesity and reproductive problems, and thus, researchers have been working on developing novel environmentally friendly plasticizers. Cyclohexane dicarboxylate, a hydrogenation product of phthalate, is an environmentally friendly plasticizer, has similar or superior plasticizing properties to phthalate plasticizers, and is degradable in the natural environment, and thus, many countries have approved it for use in the plastic industry such as toys, medical devices, and food packaging.

Because the phthalic acid ester has a benzyl ring structure and is connected with two electron-withdrawing groups, namely carboxyl, the hydrogenation reaction on the ring is difficult to occur, and therefore, how to prepare the cyclohexane dicarboxylic acid ester compound by adopting the phthalic acid ester is a key problem to be solved. The existing hydrogenation catalyst for phthalate needs to use noble metal as a main catalytic active component, so that the cost is high, and the application of the catalyst in actual production is limited. Therefore, the design and preparation of the novel catalyst which is low in price, high-efficiency and stable and is used for preparing the cyclohexanedicarboxylic ester by the catalytic hydrogenation of the phthalic ester have great significance in industrial production.

Nickel-based catalysts have received particular attention as low cost alternatives to noble metal catalysts in the catalytic hydrogenation production of various intermediates. However, the poor dispersion of nickel and the weak interaction with the support cause aggregation and sintering of nickel nanoparticles, due to inherent defects of the conventional method, thereby limiting further practical applications thereof. Thus, improving activity and stability in the preparation of nickel-based catalysts remains a challenging task.

Disclosure of Invention

The invention aims to provide a halloysite-loaded nickel-based nano catalyst to solve the problems that the existing nickel-based supported catalyst is limited by a carrier, and the nickel particles as an active component are easy to agglomerate, poor in activity and short in service life.

The second purpose of the invention is to provide a preparation method of the halloysite-loaded nickel-based nano catalyst, so as to prepare the nickel-based nano catalyst with small particle size, uniform dispersion, high activity, strong selectivity and good stability of an active component nickel particle.

The invention also aims to provide the application of the halloysite-supported nickel-based nano-catalyst in hydrogenation reaction.

One of the objects of the present invention is achieved by:

a halloysite-supported nickel-based nano catalyst has magnetism, wherein an active component Ni is dispersed in the catalyst, and the particle size of the active component Ni is less than 1nm; the active component Ni is nickel nano-particles which are distributed in the tube and outside the tube of the halloysite; magnesium oxide is also distributed outside the halloysite pipe; pores (or holes) etched by fluorine ions also exist on the surface of the halloysite.

In the halloysite-supported nickel-based nano catalyst, the content of an active component Ni is 25-30 wt%.

The specific surface area of the halloysite-loaded nickel-based nano catalyst>200m ² /g。

Pore volume of the halloysite-supported nickel-based nanocatalyst>0.5cm ³ /g。

The metal dispersity of an active component Ni in the halloysite-loaded nickel-based nano catalyst is more than 0.5%.

The metal specific surface area of an active component Ni in the halloysite-loaded nickel-based nano catalyst>1.6m ² /g。

The halloysite-loaded nickel-based nano catalyst is prepared by the following method:

(a) Ultrasonically dispersing halloysite in N-methyl pyrrolidone to obtain a uniformly dispersed halloysite solution;

(b) Adding inorganic salt of nickel, inorganic salt of magnesium, precipitator and ammonium fluoride into the halloysite solution which is uniformly dispersed, carrying out reflux reaction at 100-200 ℃, and carrying out solid-liquid separation, washing, drying and roasting in air atmosphere to obtain a catalyst precursor;

(c) And reducing the obtained catalyst precursor in a hydrogen atmosphere to obtain the halloysite-loaded nickel-based nano catalyst. After reduction, a nickel simple substance is formed on the halloysite tube body, so that the whole catalyst has magnetism.

In the step (a), the mass ratio of the halloysite to the N-methylpyrrolidone is 1; the halloysite is ultrasonically dispersed in N-methyl pyrrolidone for 0.5 to 2 hours, preferably 1 hour.

In the step (b), the precipitant is sodium hydroxide, potassium hydroxide or urea, preferably urea; the mass ratio of halloysite to inorganic salts of nickel, inorganic salts of magnesium, urea and ammonium fluoride is 1.

In step (b), the inorganic salt of nickel is an inorganic salt common to those skilled in the art, preferably a nitrate salt of nickel; the inorganic salt of magnesium is common to those skilled in the art, preferably the nitrate salt of magnesium.

In the step (b), the temperature is raised to 300-700 ℃ at the temperature raising rate of 1-10 ℃/min, and the roasting is carried out for 1-10 h.

In the step (c), the reduction temperature is 350-600 ℃, preferably 450 ℃; the reduction time is 1 to 3 hours, preferably 2 hours.

The second purpose of the invention is realized as follows:

the preparation method of the halloysite-loaded nickel-based nano catalyst comprises the following steps of:

(c) And reducing the obtained catalyst precursor in a hydrogen atmosphere to obtain the halloysite-loaded nickel-based nano catalyst.

Specifically, in the step (a), the mass ratio of 1: and (3) putting the halloysite 1 and N-methylpyrrolidone in a beaker, and performing ultrasonic dispersion for 1 hour to obtain a uniformly dispersed halloysite solution.

In step (b), the precipitating agent comprises sodium hydroxide, potassium hydroxide or urea, preferably urea; the mass ratio of halloysite to inorganic salts of nickel, inorganic salts of magnesium, urea and ammonium fluoride is 1.

The third purpose of the invention is realized by the following steps:

the halloysite-supported nickel-based nano catalyst is applied to hydrogenation reaction, particularly to the reaction of hydrogenation of phthalic acid ester to cyclohexane diformate.

In the reaction of hydrogenating phthalate to produce cyclohexane diformate, the reaction substrate may be any one of dioctyl phthalate (DOP), dimethyl phthalate (DMT), dibutyl phthalate (DBP), etc., and the solvent may be any one or mixture of more than two of methanol, ethanol, isopropanol, n-hexane, tert-butanol, ethyl acetate, 1, 4-dioxane, etc. in any proportion.

Preferably, in the reaction of generating cyclohexanedicarboxylic acid ester by hydrogenating phthalic acid ester, the nickel-based nano catalyst takes NiMg/0.96F-HNT as a catalyst, n-hexane, the catalyst and DOP are sequentially added into a high-pressure reaction kettle, the hydrogenation pressure is 5MPa, and 423K is reacted for 4 hours under the stirring condition of 400r/min to obtain 1, 2-dioctyl cyclohexanedicarboxylate (DEHHP).

The catalyst provided by the invention has excellent activity and can be compared favorably with a noble metal catalyst. In the reaction of hydrogenating phthalic acid ester to cyclohexane diformate, the conversion rate of dioctyl phthalate is 99 percent, and the selectivity of 1, 2-dioctyl cyclohexane diformate is also 99 percent; and because the catalyst has magnetism, after each reaction, the catalyst can be applied in subsequent reactions through simple magnetic separation and cleaning by an external magnetic field. The catalyst can be continuously used for 9 times, the catalytic performance is kept unchanged, and the catalyst has excellent recycling performance and good stability.

The invention effectively limits the nickel nano particles in the tube by utilizing the unique long tubular structure of the halloysite, improves the stability of the catalyst, and simultaneously, fluorine ions can carry out pore-forming on the surface of the halloysite to increase the nickel nano particles, the substrate and H ₂ Thereby increasing activity. Then adding a magnesium oxide accelerant to form a new active center on the interface of the nickel and the magnesium oxide, thereby improving the hydrogen adsorption capacity of the catalyst and further improving the activity; in addition, the addition of magnesium oxide makes nickel more dispersed, improves the dispersibility, and solves the problems of uneven distribution, large particle size, easy agglomeration and loss of nickel nanoparticles of the active component of the common nickel-based nano catalyst.

The preparation method is simple, low in cost, good in repeatability, capable of being recycled for multiple times, and wide in industrial application prospect.

Drawings

Fig. 1 is an XRD spectrum of the catalyst precursor 1 prepared in example 1 (curve b) and the catalyst precursor 1 prepared in comparative example 1 (curve a).

FIG. 2 is an XRD spectrum of the catalyst NiMg/0.96F-HNT prepared in example 1 (curve b) and the catalyst NiMg/0F-HNT prepared in comparative example 1 (curve a).

FIG. 3 is the N of the catalyst NiMg/0.96F-HNT prepared in example 1 ₂ Adsorption-desorption curve.

FIG. 4 is a graph of the pore size distribution of the catalyst NiMg/0.96F-HNT prepared in example 1.

FIG. 5 is N of the catalyst NiMg/0F-HNT prepared in comparative example 1 ₂ Adsorption-desorption curve.

FIG. 6 is a pore size distribution diagram of the catalyst NiMg/0F-HNT prepared in comparative example 1.

FIG. 7 is an SEM image of the catalyst NiMg/0.96F-HNT prepared in example 1.

FIG. 8 is an SEM image of the catalyst NiMg/0F-HNT prepared in comparative example 1.

FIG. 9 is a TEM image of the catalyst NiMg/0.96F-HNT prepared in example 1.

FIG. 10 is a TEM image of the catalyst NiMg/0F-HNT prepared in comparative example 1.

FIG. 11 is a Mapping chart of the catalyst NiMg/0.96F-HNT prepared in example 1.

FIG. 12 is the H for the catalyst NiMg/0.96F-HNT prepared in example 1 (curve b) and the catalyst NiMg/0F-HNT prepared in comparative example 1 (curve a) ₂ -a TPR map.

FIG. 13 is H for the catalyst NiMg/0.96F-HNT prepared in example 1 (curve b) and the catalyst NiMg/0F-HNT prepared in comparative example 1 (curve a) ₂ -TPD map.

FIG. 14 is an XRD spectrum of the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst Ni/0.96F-HNT prepared in comparative example 2.

FIG. 15 is an XPS spectrum of the catalyst NiMg/0.96F-HNT prepared in example 1.

FIG. 16 is H for the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst Ni/0.96F-HNT prepared in comparative example 2 ₂ -TPD map.

Detailed Description

The invention is further illustrated by the following examples, which are given by way of illustration only and are not intended to limit the scope of the invention in any way.

Procedures and methods not described in detail in the following examples are conventional methods well known in the art, and the reagents used in the examples are either analytically or chemically pure and are either commercially available or prepared by methods well known to those of ordinary skill in the art. The following examples all achieve the objects of the present invention.

Example 1

Solution A was obtained by sonicating Halloysite (HNT) (1.00 g) in 100mL (i.e., 100 g) of NMP (N-methylpyrrolidone) for one hour.Then adding Ni (NO) ₃ ) ₂ ·6H ₂ O(2.91g)、Mg(NO ₃ ) ₂ ·6H ₂ O(1.25g)、CH ₄ N ₂ O (4.80 g) and NH ₄ A mixture of F (0.96 g) was dissolved in 100mL of deionized water to give solution B. Thereafter, solution A and solution B were mixed and heated under reflux at 100 ℃ for 5 hours. Washing the precipitate with deionized water, freeze-drying, and calcining at 500 ℃ in air for 2h to obtain a catalyst precursor 1. Then at H ₂ Reducing for 2.5h at 450 ℃ in the atmosphere to obtain the catalyst NiMg/0.96F-HNT.

Comparative example 1

Solution A was obtained by sonication in 100mL of NMP for one hour of HNT (1.00 g). Then adding Ni (NO) ₃ ) ₂ ·6H ₂ O(2.91g)、Mg(NO ₃ ) ₂ ·6H ₂ O(1.25g)、CH ₄ N ₂ A mixture of O (4.80 g) was dissolved in 100mL of deionized water to give solution B. Then, solution A and solution B were mixed and heated at 100 ℃ under reflux for 5 hours. Washing the precipitate with deionized water, freeze-drying, and calcining at 500 ℃ in air for 2h to obtain the catalyst precursor 1. Then at H ₂ Reducing for 2.5h at 450 ℃ in the atmosphere to obtain the catalyst NiMg/0F-HNT.

Comparative example 2

Solution A was obtained by sonication in 100mL of NMP for one hour of HNT (1.00 g). Then adding Ni (NO) ₃ ) ₂ ·6H ₂ O(2.91g)、CH ₄ N ₂ O (4.80 g) and NH ₄ A mixture of F (0.96 g) was dissolved in 100mL of deionized water to give solution B. Then, solution A and solution B were mixed and heated under reflux at 100 ℃ for 5 hours. Washing the precipitate with deionized water, freeze drying, calcining at 500 deg.C in air for 2h ₂ Reducing for 2.5h at 450 ℃ in the atmosphere to obtain the catalyst Ni/0.96F-HNT.

The catalyst precursor 1 prepared in example 1 and the catalyst precursor 1 prepared in comparative example 1 were subjected to wide-angle XRD diffraction characterization, and XRD spectrograms thereof are shown in fig. 1. As can be seen from the figure, the diffraction peak at 12.1 ° gradually decreased in intensity with increasing addition amount of fluorine ion, indicating that the addition of fluorine ion favors the formation of mesopores.

The catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1 were subjected to wide-angle XRD diffraction characterization, as shown in FIG. 2. As can be seen from the figure, a weak Ni characteristic peak appears in the vicinity of 2 θ =44.5 ° because Ni particles are highly dispersed at the surface of the support and part of the Ni particles enter the halloysite tube. The rest diffraction peaks are all characteristic peaks of halloysite. It is worth noting that the diffraction peak of the simple substance nickel is shorter and wider after the ammonium fluoride is added, which indicates that the addition of the fluorinion is beneficial to the dispersion of the nickel nano particles. In addition, the metal particle size of elemental Ni in the catalyst was calculated according to the Scherrer equation, as shown in table 1. The particle size of the element nickel in the catalyst NiMg/0.96F-HNT prepared after the fluorinion is added is the minimum.

The main physicochemical properties of the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1 were measured by a chemical adsorption apparatus and nitrogen adsorption-desorption, and the results are shown in table 1 and fig. 3 to 6.

TABLE 1 physicochemical Properties of the different catalysts

According to the test results of Table 1, niMg/0.96F-HNT specific surface area, pore volume and hydrogen adsorption amount (232.6 m) ² g ^-1 、0.69cm ³ g ^-1 And 1.61m ³ g ^-1 ) Are all higher than NiMg/0F-HNT (39.7 m) ² g ^-1 、0.14cm ³ g ^-1 And 0.48m ³ g ^-1 ) Catalyst, indicating that fluorine ions etch silicon dioxide on the halloysite surface to form pores. The specific metal surface area and the metal dispersion degree of the catalyst NiMg/0.96F-HNT are also obviously higher than those of the NiMg/0F-HNT, which shows that the NiMg/0.96F-HNT catalyst has more active sites, more dispersed active sites, high hydrogen adsorption capacity and higher catalyst activity.

It can be seen from fig. 3-6 that the presence of type iii adsorption curves in both catalysts indicates that the catalysts both have macroporous structures, which are consistent with the natural structure of halloysite.

FIGS. 7 to 8 are SEM images of the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1. As can be seen, these two catalysts substantially retained the long straight tube structure of the halloysite, and after addition of fluoride ions, debris appeared around the long straight tube structure, demonstrating that etching of the halloysite tubular structure by fluoride ions creates pores that lead to nickel spills out of the tube or the halloysite falls off the tube structure.

FIGS. 9 to 10 are TEM images of the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1. As can be seen from the figure, when fluorine ions are not added, the catalyst NiMg/0F-HNT completely keeps the structure of the halloysite long straight tube, ni particles are uniformly distributed in and out of the halloysite tube, and no holes are formed on the surface of the halloysite, but after the fluorine ions are added, holes are formed on the halloysite, which confirms that the fluorine ions successfully form holes on the halloysite.

FIG. 11 is a Mapping chart of the catalyst NiMg/0.96F-HNT prepared in example 1. As can be seen from the figure, the elements aluminum and silicon are constituent elements of halloysite, and it is confirmed that the long straight tube is halloysite. Most of the element magnesium is distributed outside the halloysite tube, but the element nickel is distributed outside the halloysite tube. The result shows that the nickel nano particles grown in situ in the halloysite tube effectively limit the agglomeration and growth of the Ni nano particles, and simultaneously generate stronger interaction with the carrier, inhibit the loss and agglomeration of active components, and improve the activity and stability of the catalyst.

FIG. 12 is the H of the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1 ₂ -a TPR map. As shown in the figure, there are mainly two reduction peaks, the peak at 320-465 ℃ indicates that there is only a small amount of free NiO on the surface of the catalyst, and the peak at 480-590 ℃ indicates that most of the Ni in the catalyst is obtained by the reduction of NiO with strong interaction of the support. When ammonium fluoride is added, the interaction between the catalyst metal and the carrier is stronger, and the stability of the catalyst is better. This proves that strong interaction force exists between the carrier and the active component in the NiMg/0.96F-HNT catalyst, thereby inhibiting the agglomeration and loss of Ni particles in the reaction process to a certain extent and improving the stability of the catalyst.

FIG. 13 is H for the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst NiMg/0F-HNT prepared in comparative example 1 ₂ -TPD map. As can be seen from the figure, the curves for both catalysts show two main peaks between 50-200 ℃ and 300-650 ℃, which indicates the presence of both forms of hydrogenation active centers for both catalysts. Wherein the desorption peak at the lower temperature range is attributed to hydrogen adsorbed on the highly dispersed Ni nanoparticles, the desorption peak at the higher temperature range is attributed to hydrogen adsorbed on the Ni nanoparticles with poor dispersion, and the desorption peak areas at different temperature ranges represent the number of such hydrogenation active sites. After the fluorine ions are added, the catalyst NiMg/0.96F-HNT has larger desorption peak in a lower temperature range, and the total peak area is obviously larger than that of the NiMg/0F-HNT catalyst. The Ni nano particles of NiMg/0.96F-HNT have the smallest particle size and the best dispersity, so that the hydrogen adsorption capacity is stronger than that of the catalyst NiMg/0F-HNT, and the chemical adsorption capacity of hydrogen is effectively improved and the activity of the catalyst is improved after the ammonium fluoride is added to etch the surface of halloysite.

The catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst Ni/0.96F-HNT prepared in comparative example 2 were characterized by wide-angle XRD diffraction, as shown in FIG. 14. As can be seen from the figure, diffraction peaks of nickel element exist after the reduction of the two catalysts, which indicates that the active components in the two catalysts are nickel simple substances, wherein the characteristic peak of Ni at 44.5 ℃ in the NiMg/0.96F-HNT catalyst is lower, which indicates that the addition of magnesium has an effect of promoting the dispersion of Ni.

The XPS spectrum of the NiMg/0.96F-HNT catalyst prepared in example 1 is shown in FIG. 15, the spectrum of Mg2p of the catalyst is symmetrical, magnesium exists only in the form of magnesium oxide, and the reason why the characteristic peak of magnesium oxide is not observed in the XRD spectrum is probably because the magnesium oxide is too dispersed.

FIG. 16 is the H for the catalyst NiMg/0.96F-HNT prepared in example 1 and the catalyst Ni/0.96F-HNT prepared in comparative example 2 ₂ -TPD map. As can be seen from the figure, the catalyst NiMg/0.96F-HNT has two forms of hydrogenation active centers, and the catalyst Ni/0.96F-HNT has one form of hydrogenation active centers. Wherein the peak at lower temperature range is due to adsorptionHydrogen attached to highly dispersed Ni nanoparticles, the desorption peak at the higher temperature range is attributed to hydrogen adsorbed to Ni nanoparticles with poor dispersion, and the desorption peak areas at different temperature ranges represent the number of such hydrogenation active sites. The catalyst NiMg/0.96F-HNT not only has larger desorption peak in a lower temperature range, but also has a total peak area obviously larger than that of the catalyst Ni/0.96F-HNT. The Ni nano particles of NiMg/0.96F-HNT have the smallest particle size and the best dispersity, so that the hydrogen adsorption capacity is stronger than that of the catalyst Ni/0.96F-HNT, which shows that the magnesium oxide can be beneficial to the dispersion of Ni and improve the hydrogen adsorption capacity of the catalyst, thereby improving the activity of the catalyst.

Example 2

The hydrogenation of DOP was carried out by using the catalysts prepared in example 1 and comparative examples 1 to 2, respectively.

The hydrogenation of DOP was carried out in a stainless steel reactor equipped with mechanical stirring and an electrical heating system. The specific operation steps are as follows: 3.0mL of dioctyl phthalate, 0.05g of catalyst and 60mL of n-hexane were sequentially added to a 100mL reaction vessel, then three times of hydrogen was charged to displace air in the reaction vessel, and then the reaction vessel was pressurized to 2.0MPa or 5.0MPa with hydrogen, set at 150 ℃ and reacted for 4 hours with stirring at 400 rpm. After the reaction was completed and cooled to room temperature, it was separated, and the resulting product was analyzed by Agilent 7820A gas chromatograph equipped with a hydrogen flame ionization detector, and its structure was identified by Agilent 5975C GC-MS, the results of which are shown in Table 2.

TABLE 2 comparison of the catalytic performances of the different catalysts

Wherein, the first and the second end of the pipe are connected with each other,

^a : reaction conditions are as follows: 3.0mL DOP,0.05g catalyst, 60mL n-hexane, 150 ℃ and 2.0MPa H ₂ ，400rpm，4h；

^b : the reaction conditions are as follows: 3.0mL of LDOP,0.05g of catalyst, 60mL of n-hexane, 150 ℃ and 5.0MPaH ₂ ，400rpm，4h。

Example 3

The recycling performance of the catalyst NiMg/0.96F-HNT is researched by using the reaction of catalytic hydrogenation of DOP as DEHHP.

3.0mL of dioctyl phthalate, 0.05g of catalyst and 60mL of n-hexane were sequentially added to a 100mL reaction vessel, then three times of hydrogen was charged to displace air in the reaction vessel, and then the reaction vessel was pressurized to 5.0MPa with hydrogen, set at 150 ℃ and stirred at 400rpm for 4 hours. After each reaction, the catalyst is simply magnetically separated and recovered through an external magnetic field (magnet), and can be reused in the subsequent DOP hydrogenation reaction after being cleaned by n-hexane. The results show that: the NiMg/0.96F-HNT catalyst can be continuously used for 9 times, the DOP conversion rate is kept above 99%, the DEHHP selectivity is kept at 99%, and the excellent recycling performance is proved.

Claims

1. A halloysite-supported nickel-based nano catalyst is characterized in that nickel nano particles are distributed in and out of a halloysite tube, magnesium oxide is also distributed out of the halloysite tube, and holes etched by fluorine ions are also formed in the surface of the halloysite.

2. The halloysite-supported nickel-based nanocatalyst of claim 1 wherein the nickel nanoparticles have a particle size of less than 1nm.

3. The halloysite-supported nickel-based nanocatalyst of claim 1, wherein the nickel nanoparticles are present in an amount of 25 to 30wt%.

4. A method for preparing the halloysite-supported nickel-based nanocatalyst according to claim 1, which is characterized by comprising the following steps:

a. ultrasonically dispersing halloysite in N-methylpyrrolidone to obtain a halloysite solution with uniform dispersion;

b. adding inorganic salt of nickel, inorganic salt of magnesium, precipitator and ammonium fluoride into the halloysite solution which is uniformly dispersed, carrying out reflux reaction at 100-200 ℃, and carrying out solid-liquid separation, washing, drying and roasting in air atmosphere to obtain a catalyst precursor;

c. and reducing the obtained catalyst precursor in a hydrogen atmosphere to obtain the halloysite-loaded nickel-based nano catalyst.

5. The preparation method of the halloysite-supported nickel-based nanocatalyst as claimed in claim 4, wherein in the step a, the mass ratio of the halloysite to the N-methylpyrrolidone is 1-75, and the ultrasonic dispersion time is 0.5-2 h.

6. The method for preparing the halloysite-supported nickel-based nano catalyst according to claim 4, wherein in the step b, the mass ratio of halloysite to inorganic salts of nickel, inorganic salts of magnesium, a precipitating agent and ammonium fluoride is (1-0.2-3).

7. The method for preparing the halloysite-supported nickel-based nano-catalyst according to claim 4, wherein in the step b, the roasting process specifically comprises the following steps: heating to 300-700 ℃ at the heating rate of 1-10 ℃/min, and roasting for 1-10 h.

8. The method for preparing the halloysite-supported nickel-based nanocatalyst according to claim 4, wherein in the step c, the reduction temperature is 350-600 ℃, and the reduction time is 1-3 hours.

9. Use of the halloysite-supported nickel-based nanocatalyst of claim 1 in hydrogenation reactions.

10. Use according to claim 9, wherein the hydrogenation reaction is a phthalate hydrogenation reaction to form cyclohexanedicarboxylic acid esters.