CN114522703A

CN114522703A - Preparation method and application of NiO-X catalyst based on anionic surface modification

Info

Publication number: CN114522703A
Application number: CN202210184458.1A
Authority: CN
Inventors: 杜凯敏; 祁志福; 刘春红; 胡晨晖; 卓佐西; 雪小峰
Original assignee: Zhejiang Energy Group Research Institute Co Ltd
Current assignee: Zhejiang Energy Group Research Institute Co Ltd
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2022-05-24

Abstract

The invention relates to a preparation method of a NiO-X catalyst based on anionic surface modification, which comprises the following steps: preparing a NiO catalyst; preparing the anionic surface modified NiO-X catalyst. The beneficial effects of the invention are: addition of anionsThen, mixing and stirring for a long time, and adsorbing anions on the surface of the NiO catalyst to prepare the anion surface modified NiO-X catalyst; NiO shows stronger catalytic oxidation activity, the addition of the anion X plays a role in modifying the surface of the NiO, and the charge density of the surface of the NiO catalyst is improved on the basis of not changing the self structure of the NiO; the selectivity of propylene can be obviously improved under the condition of keeping the same activity of propane conversion rate, so that the yield of target products is improved. More excellent NiO-PO₄ ^3‑The catalyst can improve the propylene selectivity from 19% to more than 65% at about 10% propane conversion; the method has the advantages of simple process, mild conditions, good catalytic effect, good stability, environmental protection, energy conservation and good application prospect.

Description

Preparation method and application of NiO-X catalyst based on anionic surface modification

Technical Field

The invention relates to the technical field of catalysts, in particular to a preparation method and application of a NiO-X catalyst based on anionic surface modification.

Background

Propylene is the second major basic chemical raw material, has wide application, and downstream industries such as polypropylene, acrylonitrile and the like are very important chemical products. With the rapid development of the chemical industry, propylene is always in a state of short supply and short demand, and the main source of propylene is the traditional cracking and refining byproducts at present.

With the continuous development of shale gas in recent years, the yield of propane is increased, and the occupation ratio of new processes such as direct Propane Dehydrogenation (PDH) and the like in the propylene market is increased. Such as with Cr₂O₃The Catofin process and the FBD process which are active component catalysts, the Oleflex process which is an active component catalyst using Pt, the STAR process and the line process. The direct dehydrogenation process has the advantages that the selectivity of propylene is excellent, and the yield of propylene is considerable; however, because the reaction is limited by thermodynamic equilibrium, dehydrogenation needs to be carried out at a higher reaction temperature (> 600 ℃), the conversion rate is influenced by the reaction temperature, and the problem of carbon deposition deactivation of the catalyst is also brought at a high temperature. The selective oxidative dehydrogenation of propane is not limited by thermodynamics due to the exothermic reaction, and is theoretically more favorableHigh conversion rate can be realized at low temperature, and because of the introduction of oxygen, the problem of carbon deposition of the catalyst does not exist, the defect of direct dehydrogenation is overcome, and the method has better prospect; however, the selective oxidative dehydrogenation of propane has fewer catalysts, and the catalysts tend to be deeply oxidized rather than selectively oxidized, and how to improve the selectivity of propylene is always the challenge of the oxidative dehydrogenation process of propane.

In the selective oxidative dehydrogenation process of propane, how to improve the propylene selectivity of the catalyst is a difficult point and a hot point of research. Among transition metal oxides, NiO is one of metal oxides having high oxidation activity and having high propane conversion activity at low temperatures, and NiO is considered to be the metal oxide catalyst having the greatest prospect for oxidative dehydrogenation of propane.

The patent with the application number of CN105727984A discloses a nickel-molybdenum bimetallic oxide catalyst and a preparation method and application thereof, wherein the patent firstly synthesizes an SBA-15 molecular sieve, then uses the SBA-15 molecular sieve as a hard template, and carries out high-temperature treatment with nickel salt to obtain nickel oxide precursor powder, removes the SBA-15 hard template through a sodium hydroxide solution to obtain ordered mesoporous nickel oxide, and finally impregnates the mesoporous nickel oxide through molybdenum salt to finally obtain the nickel-molybdenum bimetallic oxide catalyst.

At present, most of regulation and control means for nickel oxide are concentrated on the aspects of impregnation loading, auxiliary agent doping and the like, and a regulation and control method for efficiently improving propylene selectivity by surface modification through self-adsorption of anions is not reported so far.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method and application of a NiO-X catalyst based on anionic surface modification.

The preparation method of the NiO-X catalyst based on the anionic surface modification comprises the following steps:

step 1, preparing a NiO catalyst: under stirring, adding H₂C₂O₄·2H₂O solution is added to Ni (CH) dropwise₃COO)₂·4H₂In O solution, and continuously stirring at room temperatureAfter a certain period of time, filtering the obtained solution, washing and drying a solid product obtained by filtering to obtain a precursor filter cake, and roasting the precursor filter cake to obtain a NiO catalyst; washing with water or ethanol;

step 2, preparing an anionic surface modified NiO-X catalyst: adding the NiO catalyst prepared in the step 1 into an anion X salt solution under the stirring condition, continuously stirring at room temperature for a set time, filtering the obtained solution, washing and drying a solid obtained by filtering, and roasting the solid to obtain an anion surface modified NiO-X catalyst; the anionic X salt solution is PO₄ ^3-、WO₄ ^2-、MoO₄ ^2-、SO₄ ^2-、B₄O₇ ^2-、SiO₃ ^2-Or CO₃ ^2-Sodium salt solution or potassium salt solution of (1).

Preferably, step 1 is H₂C₂O₄·2H₂O and Ni (CH)₃COO)₂·4H₂A molar ratio of O is 1 to 1.25, and Ni (CH)₃COO)₂·4H₂The concentration of the O solution is 0.1-0.4 mol/L.

Preferably, in step 1, H is added₂C₂O₄·2H₂O solution is added to Ni (CH) dropwise₃COO)₂·4H₂And (4) after the O solution is added, continuously stirring for 1-2 h at room temperature.

Preferably, in the step 1, drying the solid product obtained by filtering at 60-80 ℃ for 10-15 h to obtain a precursor filter cake; and then roasting the precursor filter cake for 2-4 h at 400-500 ℃.

Preferably, in step 2, the anion X salt solution is 0.01-0.04 mol/L PO₄ ^3-、WO₄ ^2-、MoO₄ ^2-、SO₄ ^2-Sodium salt solution or potassium salt solution of (1); the molar ratio of NiO to the anion X is 1 (0.5-2).

Preferably, the concentration of the anion X salt solution is 0.03-0.04 mol/L, and the molar ratio of NiO and the anion X is 0.5-1.

Preferably, in the step 2, the anion X salt solution added with the NiO catalyst is continuously stirred for 5-10 hours at room temperature, the obtained solution is filtered, the solid obtained by filtering is washed, and the solid is dried for 10-15 hours at the temperature of 60-80 ℃; and then roasting the dried solid for 2-4 hours at 400-500 ℃.

Preferably, in the step 2, the anion X salt solution added with the NiO catalyst is continuously stirred for 8-10 h at room temperature.

An application method of an anionic surface modified NiO-X catalyst comprises the following steps: the anion surface modified NiO-X catalyst is used in the reaction of preparing propylene by propane selective oxidative dehydrogenation.

The invention has the beneficial effects that:

after the anion is added, the anion is adsorbed on the surface of the NiO catalyst through long-time mixing and stirring, and the anion surface modified NiO-X catalyst is prepared; NiO shows stronger catalytic oxidation activity, the addition of the anion X plays a role in modifying the surface of the NiO, and the charge density of the surface of the NiO catalyst is improved on the basis of not changing the self structure of the NiO;

propylene is used as a product with an electron-rich structure, and the anionic surface modified NiO-X catalyst purposefully promotes the product propylene to be desorbed on the surface of the catalyst in time to a certain extent and inhibits the subsequent deep oxidation, so that the catalyst NiO-X shows excellent propylene selectivity in the propane selective oxidative dehydrogenation reaction;

the anion X salt solution selected by the invention is a corresponding Na salt or K salt solution, the more the modification is performed on the same anion, the greater the selectivity improvement is, but the upper limit of saturated adsorption modification exists, so that the salt concentration and the molar ratio of the anion X to NiO are not as high as possible, and comprehensive consideration is required. The catalyst needs to be fully washed after being fully stirred and modified, otherwise, the excessive salt solution remained on the surface can form load coverage of active sites, so that the overall activity of the catalyst is greatly reduced;

the invention can obviously improve the selectivity of propylene under the condition of keeping the same activity of propane conversion rate, thereby improving the yield of target products. Relatively excellent NiO-PO₄ ^3-The catalyst can improve the propylene selectivity from 19% to more than 65% at about 10% propane conversion; the method has the advantages of simple process, mild conditions, good catalytic effect, good stability, environmental protection, energy conservation and the like, and has better application prospect.

Drawings

FIG. 1 is a performance curve (propylene selectivity at a certain propane conversion) of propylene produced by selective oxidative dehydrogenation of propane using the anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9;

fig. 2 is an XRD spectrum of the anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9;

FIG. 3 is a Zeta potential diagram of the anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for a person skilled in the art, several modifications can be made to the invention without departing from the principle of the invention, and these modifications and modifications also fall within the protection scope of the claims of the present invention.

Comparative example 1

Preparation of NiO catalyst: under stirring, according to H₂C₂O₄·2H₂O and Ni (CH)₃COO)₂·4H₂The molar ratio of O to H is 1:1₂C₂O₄·2H₂O solution is added to Ni (CH) dropwise₃COO)₂·4H₂And (3) continuously stirring the solution in the O solution for 1h at room temperature, filtering and washing the obtained solution, drying the solution for 12h at the temperature of 60 ℃ to obtain a light green precursor filter cake, and roasting the precursor filter cake for 2h at the temperature of 500 ℃ to obtain the NiO catalyst.

The NiO catalyst prepared by the preparation method is used for carrying out reaction evaluation on the preparation of propylene by propane selective oxidative dehydrogenation.

Example 1

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

PO₄ ^3-Surface modified NiO-0.6PO₄ ^3-Preparation of the catalyst: adding NiO catalyst to 0.03mol/L of Na under stirring₃PO₄In solution, NiO and anion PO therein₄ ^3-Is 1:0.6, continuously stirring for 10h at room temperature, filtering and washing the obtained solution, drying for 12h at 60 ℃, roasting for 2h at 500 ℃ to obtain the PO base₄ ^3-Surface modified NiO-0.6PO₄ ^3-A catalyst.

PO prepared by the preparation method₄ ^3-Surface modified NiO-0.6PO₄ ^3-And (3) evaluating the reaction of preparing propylene by selective oxidative dehydrogenation of propane by using the catalyst.

Example 2

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

PO₄ ^3-Surface modified NiO-1.2PO₄ ^3-Preparation of the catalyst: NiO catalyst was added to 0.035mol/L Na with stirring₃PO₄In solution, NiO and anion PO therein₄ ^3-At room temperature for 10h, filtering and washing the obtained solution, drying at 60 ℃ for 12h, and roasting at 500 ℃ for 2h to obtain the PO base₄ ^3-Surface modified NiO-1.2PO₄ ^3-A catalyst.

PO prepared by the preparation method₄ ^3-Surface modified NiO-1.2PO₄ ^3-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 3

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

PO₄ ^3-Surface modified NiO-1.8PO₄ ^3-Preparation of the catalyst: the NiO catalyst was added to 0.04mol/L Na with stirring₃PO₄In solution, NiO and anion PO therein₄ ^3-At a molar ratio of 1:1.8, continuously stirring at room temperature for 10h, filtering, washing, and oven drying at 60 deg.CRoasting for 2 hours at 500 ℃ for 12 hours to obtain the PO base₄ ^3-Surface modified NiO-1.8PO₄ ^3-A catalyst.

PO prepared by the preparation method₄ ^3-Surface modified NiO-1.8PO₄ ^3-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 4

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

WO₄ ^2-Surface modified NiO-1.8WO₄ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂WO₄In solution, NiO and anion WO₄ ^2-At a molar ratio of 1:1.8, continuously stirring at room temperature for 10h, filtering and washing the obtained solution, drying at 60 ℃ for 12h, and roasting at 500 ℃ for 2h to obtain the WO-based catalyst₄ ^2-Surface modified NiO-1.8WO₄ ^2-A catalyst.

WO prepared by the preparation method₄ ^2-Surface modified NiO-1.8WO₄ ^2-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 5

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

MoO₄ ^2-Surface modified NiO-1.8MoO₄ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂MoO₄In solution, NiO and anion MoO₄ ^2-The molar ratio of the organic solvent to the organic solvent is 1:1.8, the obtained solution is filtered and washed after being continuously stirred for 10 hours at room temperature, dried for 12 hours at the temperature of 60 ℃, and roasted for 2 hours at the temperature of 500 ℃ to obtain the MoO-based organic solvent₄ ^2-Surface modified NiO-1.8MoO₄ ^2-A catalyst.

MoO prepared by the preparation method₄ ^2-Surface modified NiO-1.8MoO₄ ^2-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 6

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

SO₄ ^2-Surface modified NiO-1.8SO₄ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂SO₄In solution, NiO and anion SO₄ ^2-At a molar ratio of 1:1.8, continuously stirring at room temperature for 10h, filtering, washing, drying at 60 deg.C for 12h, and calcining at 500 deg.C for 2h to obtain the final product₄ ^2-Surface modified NiO-1.8SO₄ ^2-A catalyst.

SO prepared by the preparation method₄ ^2-Surface modified NiO-1.8SO₄ ^2-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 7

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

B₄O₇ ^2-Surface modified NiO-1.8B₄O₇ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂B₄O₇In solution, NiO and anion B₄O₇ ^2-At a molar ratio of 1:1.8, continuously stirring at room temperature for 10h, filtering and washing the obtained solution, drying at 60 ℃ for 12h, and roasting at 500 ℃ for 2h to obtain the base B₄O₇ ^2-Surface modified NiO-1.8B₄O₇ ^2-A catalyst.

B prepared by the preparation method₄O₇ ^2-Surface modified NiO-1.8B₄O₇ ^2-And (3) evaluating the reaction of preparing propylene by selective oxidative dehydrogenation of propane by using the catalyst.

Example 8

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

SiO₃ ^2-Surface modified NiO-1.8SiO₃ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂SiO₃In solution, NiO and anion SiO₃ ^2-The molar ratio of (1: 1.8) is kept stirring for 10h at room temperature, the obtained solution is filtered and washed, dried for 12h at 60 ℃, and roasted for 2h at 500 ℃ to obtain the SiO-based catalyst₃ ^2-Surface modified NiO-1.8SiO₃ ^2-A catalyst.

SiO prepared by the preparation method₃ ^2-Surface modified NiO-1.8SiO₃ ^2-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

Example 9

NiO catalyst the NiO catalyst prepared in comparative example 1 was used.

CO₃ ^2-Surface modified NiO-1.8CO₃ ^2-Preparation of the catalyst: adding NiO catalyst to 0.04mol/L Na under stirring₂CO₃In solution, NiO and anion CO₃ ^2-The molar ratio of (1: 1.8) is kept stirring for 10h at room temperature, the obtained solution is filtered and washed, dried for 12h at 60 ℃, and roasted for 2h at 500 ℃ to obtain the catalyst based on CO₃ ^2-Surface modified NiO-1.8CO₃ ^2-A catalyst.

CO prepared by the preparation method₃ ^2-Surface modified NiO-1.8CO₃ ^2-The catalyst is used for carrying out the reaction evaluation of preparing the propylene by the selective oxidative dehydrogenation of the propane.

The particle size of the anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9 is shown in table 1 below, the XRD spectra of the anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9 are shown in fig. 2, the Zeta potentials of the anionic surface-modified catalysts prepared in comparative example 1 and examples 1 to 9 are shown in fig. 3, and the catalytic performances of the NiO catalyst and the anionic surface-modified NiO-X catalyst for propane selective oxidative dehydrogenation to propylene are shown in table 2 below.

As shown in fig. 1 to fig. 3, by the catalyst preparation method of the present invention, the physical structure (XRD crystal phase, particle size, etc.) of the catalyst itself is not significantly affected and changed, and on the basis of not changing the structure itself, the charge density on the surface of the catalyst can be increased, and the timely desorption of the electron-rich structure product on the surface of the catalyst can be specifically promoted, so as to increase the selectivity of the corresponding product. Therefore, in the reaction of preparing propylene by selective oxidative dehydrogenation of propane, compared with NiO, the catalyst NiO-X has the advantage that the propylene selectivity is obviously improved.

Table 1 table of particle size of anionic surface-modified catalysts prepared in comparative example 1 and examples 3 to 9

TABLE 2 catalytic Performance of propane-selective oxydehydrogenation to propene over NiO catalyst and anionic surface-modified NiO-X catalyst

Claims

1. A preparation method of a NiO-X catalyst based on anionic surface modification is characterized by comprising the following steps:

step 1, preparing a NiO catalyst: under stirring, adding H₂C₂O₄·2H₂O solution is added to Ni (CH) dropwise₃COO)₂·4H₂In the O solution, continuously stirring at room temperature for a set time, filtering the obtained solution, washing and drying a solid product obtained by filtering to obtain a precursor filter cake, and then adding the precursor filter cakeRoasting to obtain NiO catalyst;

step 2, preparing an anionic surface modified NiO-X catalyst: adding the NiO catalyst prepared in the step 1 into an anion X salt solution under the stirring condition, continuously stirring at room temperature for a set time, filtering the obtained solution, washing and drying a solid obtained by filtering, and roasting the solid to obtain an anion surface modified NiO-X catalyst; the anionic X salt solution is PO₄ ^3-、WO₄ ^2-、MoO₄ ^2-、SO₄ ^2-、B₄O₇ ^2-、SiO₃ ^2-Or CO₃ ^2-Sodium salt solution or potassium salt solution of (2).

2. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 1, which is characterized in that: step 1H₂C₂O₄·2H₂O and Ni (CH)₃COO)₂·4H₂A molar ratio of O is 1 to 1.25, and Ni (CH)₃COO)₂·4H₂The concentration of the O solution is 0.1-0.4 mol/L.

3. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 1, which is characterized in that: in step 1, H is₂C₂O₄·2H₂O solution is added to Ni (CH) dropwise₃COO)₂·4H₂And (4) after the O solution is added, continuously stirring for 1-2 h at room temperature.

4. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 1, which is characterized in that: drying the solid product obtained by filtering at the temperature of 60-80 ℃ for 10-15 h to obtain a precursor filter cake in the step 1; and then roasting the precursor filter cake for 2-4 h at 400-500 ℃.

5. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 1, which is characterized in that: in step 2, an anionic X salt solutionPO of 0.01-0.04 mol/L₄ ^3-、WO₄ ^2-、MoO₄ ^2-、SO₄ ^2-Sodium salt solution or potassium salt solution of (1); the molar ratio of NiO to the anion X is 0.5-2.

6. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 5, which is characterized in that: the concentration of the anion X salt solution is 0.03-0.04 mol/L, and the molar ratio of NiO to the anion X is 0.5-1.

7. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 1, which is characterized in that: continuously stirring the anion X salt solution added with the NiO catalyst for 5-10 h at room temperature, filtering the obtained solution, washing the solid obtained by filtering, and drying for 10-15 h at 60-80 ℃; and then roasting the dried solid for 2-4 hours at 400-500 ℃.

8. The method for preparing the NiO-X catalyst based on the anionic surface modification of claim 7, which is characterized in that: and 2, continuously stirring the anion X salt solution added with the NiO catalyst for 8-10 h at room temperature.

9. A method of using the anionic surface modified NiO-X catalyst made by the method of any of claims 1 to 8, characterized in that: the anion surface modified NiO-X catalyst is used in the reaction of preparing propylene by propane selective oxidative dehydrogenation.