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

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

Ni-based nanocatalyst supported by halloysite and its preparation method and application

technical field

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

Background technique

Phthalate ester compounds are plasticizers that can greatly improve the flexibility and durability of plastic products; the use of phthalate ester compounds is huge, with the annual consumption reaching 8.4 million tons in 2014 alone , accounting for 70% of global usage. But phthalates are also one of the main chemicals that disrupt the endocrine system and cause cancer, obesity and reproductive problems. Therefore, researchers are working hard to develop new environmentally friendly and friendly plasticizers. Cyclohexanedicarboxylate compound, the hydrogenation product of phthalate, is an environmentally friendly plasticizer. Compared with ophthalmic plasticizers, its plasticizing performance is similar or better, and it can be used in It degrades in the natural environment, so many countries have approved its use in plastic industries such as toys, medical devices and food packaging.

Since phthalate has a benzyl ring structure and is connected with two electron-withdrawing groups-carboxyl, the hydrogenation reaction on the ring is difficult to occur. Therefore, how to use phthalate to prepare cyclohexanedi Carboxylate compounds are a key issue that needs to be addressed. Existing hydrogenation catalysts for phthalates need noble metals as the main catalytic active components, and the high cost limits their application in actual production. Therefore, it is of great significance in industrial production to design and prepare a cheap, efficient and stable new catalyst for the catalytic hydrogenation of phthalates to prepare cyclohexanedicarboxylates.

Nickel-based catalysts have received particular attention as low-cost alternatives to noble metal catalysts in catalytic hydrogenation to produce various intermediates. However, due to the inherent defects of the conventional method, the poor dispersion of nickel and the weak interaction with the support lead to the aggregation and sintering of nickel nanoparticles, thus limiting its further practical application. Therefore, improving the activity and stability in the preparation of Ni-based catalysts is still a challenging task.

Contents of the invention

One of the purposes of the present invention is to provide a halloysite-supported nickel-based nano-catalyst to solve the problems that the existing nickel-based supported catalyst is limited by the carrier, and the nickel particles of the active component are easy to agglomerate, have poor activity and short service life.

The second object of the present invention is to provide a method for preparing a halloysite-loaded nickel-based nanocatalyst, so as to obtain the nickel particle size of the active component, which is uniformly dispersed, high in activity, strong in selectivity and good in stability. based nanocatalysts.

The third object of the present invention is to provide the application of the aforementioned halloysite-supported nickel-based nano-catalyst in hydrogenation reaction.

One of the purpose of the present invention is to realize like this:

A nickel-based nanocatalyst supported by halloysite, the catalyst has magnetism, active component Ni is dispersed in the catalyst, and the particle diameter of the active component Ni is <1nm; the active component Ni is specifically nickel nanoparticles, Nickel nanoparticles are distributed inside and outside the halloysite tube; magnesium oxide is also distributed outside the halloysite tube; and there are holes (or holes) etched by fluoride ions on the surface of the halloysite.

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

The specific surface area of the nickel-based nano-catalyst supported by halloysite is >200m ² /g.

The pore volume of the halloysite-supported nickel-based nanocatalyst is >0.5 cm ³ /g.

The metal dispersion of the active component Ni in the halloysite-supported nickel-based nano-catalyst is greater than 0.5%.

The metal specific surface area of the active component Ni in the halloysite-supported nickel-based nano-catalyst is greater than 1.6m ² /g.

The nickel-based nanocatalyst supported by halloysite is prepared by the following method:

(a) ultrasonically dispersing the halloysite in N-methylpyrrolidone to obtain a uniformly dispersed halloysite solution;

(b) Add nickel inorganic salt, magnesium inorganic salt, precipitant and ammonium fluoride to the uniformly dispersed halloysite solution, carry out reflux reaction at 100-200°C, and separate solid-liquid, wash, dry, air After roasting under the atmosphere, the catalyst precursor is obtained;

(c) reducing the obtained catalyst precursor in a hydrogen atmosphere to obtain a halloysite-supported nickel-based nano-catalyst. After the reduction, a nickel element is formed on the halloysite tube, thus making the entire catalyst magnetic.

In step (a), the mass ratio of halloysite to N-methylpyrrolidone is 1:75-125, preferably 1:100; ultrasonically dispersing halloysite in N-methylpyrrolidone for 0.5-2h, preferably 1h.

In step (b), described precipitation agent is sodium hydroxide, potassium hydroxide or urea etc., preferably urea; The mass ratio of halloysite and the inorganic salt of nickel, the inorganic salt of magnesium, urea, ammonium fluoride is 1: 0.2～3:0.1～2:1～6:0.1～2, preferably 1:2.8～3:1.2～1.3:4.7～4.9:0.9～1.0, more preferably 1:2.91:1.25:4.8:0.96.

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

In step (b), the temperature is raised to 300-700° C. at a heating rate of 1-10° C./min, and calcined for 1-10 hours.

In step (c), the reduction temperature is 350-600°C, preferably 450°C; the reduction time is 1-3h, preferably 2h.

The present invention is that two of purpose are realized like this:

The preparation method of the nickel-based nano-catalyst supported by aforesaid halloysite comprises the steps:

(a) ultrasonically dispersing the halloysite in N-methylpyrrolidone to obtain a uniformly dispersed halloysite solution;

(b) Add nickel inorganic salt, magnesium inorganic salt, precipitant and ammonium fluoride to the uniformly dispersed halloysite solution, carry out reflux reaction at 100-200°C, and separate solid-liquid, wash, dry, air After roasting under the atmosphere, the catalyst precursor is obtained;

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

In step (a), the mass ratio of halloysite to N-methylpyrrolidone is 1:0.5-2, preferably 1:1; ultrasonically dispersing halloysite in N-methylpyrrolidone for 0.5-2h, preferably 1h.

Specifically, in step (a), halloysite and N-methylpyrrolidone with a mass ratio of 1:1 were used in a beaker and ultrasonically dispersed for 1 hour to obtain a uniformly dispersed halloysite solution.

In step (b), the precipitation agent includes 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 1:0.2 ~3:0.1~2:1~6:0.1~2, preferably 1:2.8~3:1.2~1.3:4.7~4.9:0.9~1.0, more preferably 1:2.91:1.25:4.8:0.96.

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

In step (b), the temperature is raised to 300-700° C. at a heating rate of 1-10° C./min, and calcined for 1-10 hours.

In step (c), the reduction temperature is 350-600°C, preferably 450°C; the reduction time is 1-3h, preferably 2h.

The present invention is that object three is achieved in this way:

The aforementioned nickel-based nano-catalyst supported by halloysite is used in hydrogenation reaction, especially in the reaction of phthalate hydrogenation to generate cyclohexane dicarboxylate.

In the hydrogenation of phthalate to generate cyclohexanedicarboxylate, the reaction substrates can be dioctyl phthalate (DOP), dimethyl phthalate (DMT), phthalate Any one of compounds such as dibutyl formate (DBP), the solvent used can be selected from methanol, ethanol, isopropanol, n-hexane, tert-butanol, ethyl acetate, 1,4-dioxane, etc. A mixture of any one or two or more of them in any proportion.

Preferably, NiMg/0.96F-HNT is used as catalyst in the hydrogenation of phthalate to generate cyclohexane dicarboxylate with nickel-based nano-catalyst, and n-hexane, catalyst and DOP are sequentially added to the autoclave , add hydrogen pressure to 5MPa, and react at 423K for 4h under 400r/min stirring condition to obtain dioctyl 1,2-cyclohexanedicarboxylate (DEHHP).

The catalyst provided by the invention has excellent activity, comparable to that of noble metal catalysts. In the hydrogenation of phthalate to generate cyclohexanedicarboxylate, the conversion rate of dioctyl phthalate is 99%, and the selectivity of dioctyl 1,2-cyclohexanedicarboxylate is also high. 99%; and because the catalyst is magnetic, after each reaction, simple magnetic separation and cleaning by an external magnetic field can be used in subsequent reactions. The catalyst can be used continuously for 9 times, the catalytic performance remains unchanged, and it has excellent recycling performance and good stability.

The invention utilizes the unique long tubular structure of halloysite to effectively confine nickel nanoparticles in its tube, which improves the stability of the catalyst. At the same time, fluorine ions can make holes on the surface of halloysite, increasing the contact between nickel nanoparticles and the substrate. Exposure to _H2 increases activity. Adding a magnesia promoter, a new active center is formed at the interface between nickel and magnesia, which improves the hydrogen adsorption capacity of the catalyst and further improves the activity; moreover, the addition of magnesia makes the nickel more dispersed and improves the dispersion. It improves the problems of uneven distribution, large particle size, easy agglomeration and loss of nickel nanoparticles, the active component of general nickel-based nanocatalysts.

The preparation method of the present invention is simple, low in cost, good in repeatability, and can be recycled for many times, and has wide industrial application prospects.

Description of drawings

Figure 1 is the XRD spectrum of the catalyst precursor 1 (curve b) prepared in Example 1 and the catalyst precursor 1 (curve a) prepared in Comparative Example 1.

Fig. 2 is the XRD spectrogram of the catalyst NiMg/0.96F-HNT (curve b) prepared in Example 1 and the catalyst NiMg/OF-HNT (curve a) prepared in Comparative Example 1.

Fig. ₃ is the N adsorption-desorption curve of the catalyst NiMg/0.96F-HNT prepared in Example 1.

Fig. 4 is a pore size distribution diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1.

Fig. ₅ is the N adsorption-desorption curve of the catalyst NiMg/OF-HNT prepared in Comparative Example 1.

6 is a pore size distribution diagram of the catalyst NiMg/OF-HNT prepared in Comparative Example 1.

7 is a SEM image of the catalyst NiMg/0.96F-HNT prepared in Example 1.

Fig. 8 is the SEM image of the catalyst NiMg/OF-HNT prepared in Comparative Example 1.

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

10 is a TEM image of the catalyst NiMg/OF-HNT prepared in Comparative Example 1.

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

Fig. 12 is the H ₂ -TPR diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 (curve b) and the catalyst NiMg/OF-HNT prepared in Comparative Example 1 (curve a).

13 is the H ₂ -TPD diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 (curve b) and the catalyst NiMg/OF-HNT prepared in Comparative Example 1 (curve a).

14 is the 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 the XPS spectrum of the catalyst NiMg/0.96F-HNT prepared in Example 1.

16 is the H ₂ -TPD diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst Ni/0.96F-HNT prepared in Comparative Example 2.

detailed description

The present invention will be further elaborated below in conjunction with the examples, and the following examples are only for illustration and do not limit the protection scope of the present invention in any way.

The processes 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 all analytically pure or chemically pure, and all of them are commercially available or prepared by methods well known to those of ordinary skill in the art. The following examples have all achieved the object of the present invention.

Example 1

Solution A was obtained by sonicating halloysite (HNT) (1.00 g) in 100 mL (ie 100 g) of NMP (N-methylpyrrolidone) for one hour. Then Ni(NO ₃ ) ₂ ·6H ₂ O (2.91g), Mg(NO ₃ ) ₂ ·6H ₂ O (1.25g), CH ₄ N ₂ O (4.80g) and NH ₄ F (0.96g) The mixture was dissolved in 100 mL of deionized water to obtain solution B. Afterwards, solution A and solution B were mixed and heated to reflux at 100° C. for 5 hours. The precipitate was washed with deionized water, freeze-dried, and calcined at 500° C. in air for 2 h to obtain catalyst precursor 1 . Afterwards, it was reduced at 450 °C for 2.5 h in H ₂ atmosphere to obtain the catalyst NiMg/0.96F-HNT.

Comparative example 1

Solution A was obtained by sonicating HNT (1.00 g) in 100 mL NMP for one hour. Then a mixture of Ni(NO ₃ ) ₂ ·6H ₂ O (2.91 g), Mg(NO ₃ ) ₂ ·6H ₂ O (1.25 g), CH ₄ N ₂ O (4.80 g) was dissolved in 100 mL of deionized water, Solution B is obtained. Then, solution A and solution B were mixed and heated to reflux at 100° C. for 5 hours. The precipitate was washed with deionized water, freeze-dried, and calcined at 500° C. in air for 2 h to obtain catalyst precursor 1 . Afterwards, it was reduced at 450°C for 2.5 h in H ₂ atmosphere to obtain the catalyst NiMg/OF-HNT.

Comparative example 2

Solution A was obtained by sonicating HNT (1.00 g) in 100 mL NMP for one hour. Then a mixture of Ni(NO ₃ ) ₂ ·6H ₂ O (2.91 g), CH ₄ N ₂ O (4.80 g) and NH ₄ F (0.96 g) was dissolved in 100 mL of deionized water to obtain solution B. Then, solution A and solution B were mixed and heated to reflux at 100° C. for 5 hours. The precipitate was washed with deionized water, freeze-dried, calcined in air at 500°C for 2h, and reduced in _H2 atmosphere at 450°C for 2.5h 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 characterized by wide-angle XRD diffraction, and their XRD spectra are shown in FIG. 1 . It can be seen from the figure that the intensity of the diffraction peak at 12.1° decreases gradually with the increasing amount of fluoride ions added, which indicates that the addition of fluoride ions is beneficial to the formation of mesopores.

The catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst NiMg/OF-HNT prepared in Comparative Example 1 were characterized by wide-angle XRD diffraction, as shown in FIG. 2 . It can be seen from the figure that there is a weak Ni characteristic peak around 2θ=44.5°, which is due to the highly dispersed Ni particles on the surface of the support and some Ni particles enter the halloysite tubes. The rest of the diffraction peaks are characteristic peaks of halloysite. It is worth noting that after the addition of ammonium fluoride, the diffraction peaks of elemental nickel become shorter and wider, indicating that the addition of fluoride ions is beneficial to the dispersion of nickel nanoparticles. 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 element nickel in the catalyst NiMg/0.96F-HNT prepared after adding fluoride ions is the smallest.

The catalyst NiMg/0.96F-HNT prepared by embodiment 1 and the catalyst NiMg/0F-HNT prepared by comparative example 1 were tested by chemical adsorption instrument and nitrogen adsorption-desorption, and the results are shown in Table 1 and Shown in Figures 3-6.

Table 1 Physicochemical properties of different catalysts

According to the test results in Table 1, the specific surface area, pore volume and hydrogen adsorption capacity (232.6m ² g ^-1 , 0.69cm ³ g ^-1 and 1.61m ³ g ^-1 ) of NiMg/0.96F-HNT are higher than those of NiMg/0F -HNT (39.7m ² g ^-1 , 0.14cm ³ g ^-1 and 0.48m ³ g ^-1 ) catalysts, indicating that fluoride ions etched the silicon dioxide on the surface of halloysite to form holes. The metal specific surface area and metal dispersion of the catalyst NiMg/0.96F-HNT are also significantly higher than those of NiMg/0F-HNT, indicating that the NiMg/0.96F-HNT catalyst has more active sites, the active sites are more dispersed, and the hydrogen adsorption capacity is high. Higher activity.

It can be seen from Figures 3 to 6 that the presence of Type III adsorption curves in the two catalysts indicates that there is a macroporous structure in the catalysts, which is consistent with the natural structure of halloysite.

7 to 8 are SEM images of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst NiMg/OF-HNT prepared in Comparative Example 1. It can be seen from the figure that the two catalysts basically retain the long straight tube structure of halloysite. After adding fluoride ions, debris appears around the long straight tube structure, which proves that the fluoride ions etched the halloysite tubular structure. Pores are created that cause nickel inside the tube to spill out of the tube or halloysite to fall off the tube structure.

9 to 10 are TEM images of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst NiMg/OF-HNT prepared in Comparative Example 1. It can be seen from the figure that when no fluoride ions are added, the catalyst NiMg/0F-HNT completely retains the halloysite long straight tube structure, and the Ni particles are evenly distributed inside and outside the halloysite tube, and there is no hole on the halloysite surface , but after adding fluoride ions, holes appeared in halloysite, which confirmed that fluoride ions successfully made holes in halloysite.

Fig. 11 is a Mapping diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1. It can be seen from the figure that the elements aluminum and silicon are the constituent elements of halloysite, which confirms that the long straight tube is halloysite. Most of the element magnesium is distributed outside the halloysite tube, but the element nickel is distributed both inside and outside the halloysite tube. This shows that the in-situ growth of Ni nanoparticles in the halloysite tube effectively limits the agglomeration and growth of Ni nanoparticles, and at the same time produces a strong interaction with the carrier, inhibits the loss and agglomeration of active components, and improves the activity and stability of the catalyst. .

FIG. 12 is the H ₂ -TPR diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst NiMg/OF-HNT prepared in Comparative Example 1. FIG. As shown in the figure, there are mainly two reduction peaks. The peak at 320-465°C indicates that there is only a small amount of free NiO on the surface of the catalyst, while the peak at 480-590°C indicates that most of the Ni in the catalyst is strongly interacted by the support. NiO reduction obtained. When ammonium fluoride is added, the interaction between the catalyst metal and the support is stronger, and the stability of the catalyst is better. This proves that there is a strong interaction between the support and the active components in the NiMg/0.96F-HNT catalyst, which can inhibit the agglomeration and loss of Ni particles during the reaction process to a certain extent and improve the stability of the catalyst.

Fig. 13 is the H ₂ -TPD diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst NiMg/OF-HNT prepared in Comparative Example 1. It can be seen from the figure that the curves of the two catalysts both show two main peaks between 50-200°C and 300-650°C, which indicates that both catalysts have two forms of hydrogenation active centers. Among them, the desorption peak in the lower temperature range is attributed to the hydrogen adsorbed on the highly dispersed Ni nanoparticles, and the desorption peak in the higher temperature range is attributed to the hydrogen adsorbed on the poorly dispersed Ni nanoparticles. The desorption peak area in the temperature range represents the number of hydrogenation active sites. After the addition of fluoride ions, the catalyst NiMg/0.96F-HNT not only has a larger desorption peak in the lower temperature range, but also the total peak area is significantly larger than that of the NiMg/0F-HNT catalyst. It shows that the Ni nanoparticles of NiMg/0.96F-HNT have the smallest particle size and the best dispersion, which leads to a stronger hydrogen adsorption capacity than the catalyst NiMg/0F-HNT. The chemical adsorption capacity of hydrogen improves the activity of the catalyst.

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 . It can be seen from the figure that there are diffraction peaks of nickel element after the reduction of the two catalysts, indicating that the active components in the two catalysts are nickel simple substance, and the Ni at 44.5° in the NiMg/0.96F-HNT catalyst The characteristic peak is lower, which shows that the addition of magnesium can promote the dispersion of Ni.

The XPS spectrum of the catalyst NiMg/0.96F-HNT prepared in Example 1 is shown in Figure 15. The Mg2p spectrum of the catalyst is left-right symmetrical, indicating that magnesium exists only in the form of magnesium oxide, and no magnesium oxide characteristics can be observed in the XRD spectrum The reason for the peak may be due to too dispersed MgO.

16 is the H ₂ -TPD diagram of the catalyst NiMg/0.96F-HNT prepared in Example 1 and the catalyst Ni/0.96F-HNT prepared in Comparative Example 2. It can be seen from the figure that the catalyst NiMg/0.96F-HNT has two forms of hydrogenation active centers, and Ni/0.96F-HNT has one form of hydrogenation active centers. Among them, the desorption peak in the lower temperature range is attributed to the hydrogen adsorbed on the highly dispersed Ni nanoparticles, and the desorption peak in the higher temperature range is attributed to the hydrogen adsorbed on the poorly dispersed Ni nanoparticles. The desorption peak area in the temperature range represents the number of hydrogenation active sites. The catalyst NiMg/0.96F-HNT not only has larger desorption peaks in the lower temperature range, but also the total peak area is significantly larger than that of the catalyst Ni/0.96F-HNT. It shows that the Ni nanoparticles of NiMg/0.96F-HNT have the smallest particle size and the best dispersibility, resulting in stronger hydrogen adsorption capacity than the catalyst Ni/0.96F-HNT, which shows that magnesium oxide can be beneficial to the dispersion of Ni and improve the hydrogen absorption of the catalyst. Adsorption capacity, thereby improving catalyst activity.

Example 2

The catalysts prepared in Example 1 and Comparative Examples 1-2 were used to carry out the hydrogenation reaction of DOP.

The hydrogenation reaction of DOP is carried out in a stainless steel reactor equipped with mechanical stirring and electric heating system. The specific operation steps are as follows: add 3.0mL of dioctyl phthalate, 0.05g of catalyst, and 60mL of n-hexane into a 100mL reactor in sequence, then fill the reactor with hydrogen three times to replace the air in the reactor, and then add Press down to 2.0MPa or 5.0MPa, set the temperature to 150°C, and react for 4h under the condition of stirring at 400rpm. After the reaction was completed and dropped to room temperature, it was separated, and the obtained product was analyzed by an Agilent 7820A gas chromatograph equipped with a hydrogen flame ion detector, and its structure was identified by Agilent 5975C GC-MS. The results are shown in Table 2.

Table 2 Comparison of catalytic performance of different catalysts

in,

^a : Reaction conditions: 3.0mL DOP, 0.05g catalyst, 60mL n-hexane, 150°C, 2.0MPa H ₂ , 400rpm, 4h;

^b : Reaction conditions: 3.0mL DOP, 0.05g catalyst, 60mL n-hexane, 150°C, 5.0MPaH ₂ , 400rpm, 4h.

Example 3

The recycling performance of the catalyst NiMg/0.96F-HNT was studied by taking DOP catalytic hydrogenation as DEHHP reaction.

Add 3.0mL of dioctyl phthalate, 0.05g of catalyst, and 60mL of n-hexane into a 100mL reactor in sequence, then fill the reactor with hydrogen three times to replace the air in the reactor, and then pressurize it to 5.0MPa with hydrogen, And the temperature was set to 150° C., and the reaction was performed for 4 hours under the condition of stirring at 400 rpm. After the completion of each reaction, the catalyst is recovered by simple magnetic separation through an external magnetic field (magnet), and after being washed with n-hexane, it can be used in the subsequent DOP hydrogenation reaction. The results show that the NiMg/0.96F-HNT catalyst can be used continuously for 9 times, the conversion rate of DOP is kept above 99%, and the selectivity of DEHHP is kept at 99%, which proves that it has excellent recycling performance.

Claims (10)

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.

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