Hydroxylated nickel species-loaded silicon-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a hydroxylated nickel species-loaded silicon-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. According to the invention, Ni is loaded on a specific silicon-based carrier, so that the hydroxylated nickel species loaded silicon-based catalyst with high catalytic activity and stability is obtained. The Ni metal in the obtained catalyst is uniformly and dispersedly distributed in the silicon-based carrier, and for a methane dry reforming reaction, the catalyst can maintain high catalytic activity of at least 170 hours at the reaction temperature of 750 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a silicon-based catalyst loaded with nickel hydroxylate species and a preparation method and application thereof. Background Art

[0002] Dry reforming of methane (DRM) is a very promising reaction that can convert two major greenhouse gases, CH4 and CO2, into valuable syngas CO and H2. Syngas is an important industrial intermediate that can be used to synthesize valuable energy chemicals such as olefins, alkanes and liquid hydrocarbons. Ni-based catalysts are the preferred catalysts for DRM reactions due to their high catalytic activity and cost-effectiveness.

[0003] Since the DRM reaction is a strong thermodynamic endothermic reaction, the reactants can only be activated well at higher temperatures. However, Ni-based catalysts are often prone to carbon deposition and sintering at high temperatures of 600-800°C due to their strong CH bond breaking ability, which leads to catalyst deactivation, and this phenomenon is more serious at low loadings (<1%). In order to avoid sintering and carbon deposition, optimizing the catalyst support material is considered to be an effective method to provide stable and efficient DRM catalysts.

[0004] Silicon-based supports are ideal supports for Ni-based catalysts for methane dry reforming. They can provide rich pore structures to anchor metal particles and inhibit metal particle aggregation. Although a lot of research has been done in this field, commonly used silicon-based supports still have a series of problems in practical applications. Usually, the preparation of supported catalysts adopts the method of impregnating the support with a metal precursor solution. However, the active metal Ni in the catalyst prepared by the impregnation method using ordinary commercial silicon-based supports is still extremely prone to sintering, thereby reducing the utilization rate of the active metal and rapidly deactivating during the reaction. Summary of the invention

[0005] The object of the present invention is to provide a silicon-based catalyst loaded with nickel hydroxylate species, and a preparation method and application thereof. By loading Ni on a specific silicon-based carrier, a silicon-based catalyst loaded with nickel hydroxylate species with high catalytic activity and stability is obtained. In the obtained catalyst, Ni metal is uniformly and dispersedly distributed in the silicon-based carrier, and for a methane dry reforming reaction, the catalyst can maintain a high catalytic activity for at least 170 hours at a reaction temperature of 750°C.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing a silicon-based catalyst loaded with nickel hydroxylate species, comprising the following steps:

[0008] Using Ni 2+ The silicon-based carrier is impregnated with a solution of A, the silicon-based carrier is taken out and dried after impregnation, calcined A, and then reduced to obtain the silicon-based catalyst loaded with nickel hydroxylate species;

[0009] The silicon-based carrier is a self-supporting five-membered ring high-silicon zeolite, and the preparation steps include:

[0010] Tetrabutylammonium hydroxide is dissolved in water, and ethyl orthosilicate is added. After mixing evenly, a solvent thermal reaction is carried out. The obtained solid product is dried and calcined to obtain the self-supporting five-membered ring high-silicon zeolite.

[0011] The specific silicon-based carrier provided by the present invention - self-supporting five-membered ring high-silicon zeolite, can form hydroxylated nickel species during the impregnation process. This nickel species is not prone to sintering and carbon deposition during the catalytic process, thereby maintaining good stability. In addition, on the self-supporting five-membered ring high-silicon zeolite carrier, the nickel species can maintain a smaller particle size, thereby obtaining good activity.

[0012] Preferably, the Ni-containing 2+ Ni in solution 2+ The usage ratio of the silica-based carrier is 1-3 mmol:1 g.

[0013] The silicon-based catalyst loaded with nickel hydroxylate species provided by the present invention requires less nickel metal, and a high-performance catalyst can be prepared with a low nickel loading amount, so the catalyst cost is lower and is more suitable for industrial production and market promotion and application.

[0014] Preferably, the Ni-containing 2+ Ni in solution 2+ The concentration is 0.5~3mol / L.

[0015] Preferably, the calcination A is carried out at a temperature of 500 to 600° C. and for a time of 5 to 6 hours.

[0016] Optionally, the reduction is carried out in a hydrogen atmosphere or a mixed atmosphere containing hydrogen, and the reduction temperature is 700-800°C.

[0017] Preferably, the molar ratio of the tetrabutylammonium hydroxide to the ethyl orthosilicate is 0.3-0.4:0.8-1.2.

[0018] Preferably, the temperature of the solvent thermal reaction is 110-120° C. and the time is 45-50 hours.

[0019] Preferably, the calcination B is carried out at a temperature of 500 to 600° C. and for a time of 54 to 6 hours.

[0020] The second technical solution of the present invention is to provide a silicon-based catalyst loaded with nickel hydroxylate species prepared according to the preparation method of the silicon-based catalyst loaded with nickel hydroxylate species.

[0021] The second technical solution of the present invention is to provide an application of the above-mentioned silicon-based catalyst loaded with nickel hydroxylate species in catalytic methane dry reforming.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The method for preparing the silicon-based catalyst loaded with nickel hydroxylate species provided by the present invention has high repeatability and good universality. After a simple impregnation method, a high-performance silicon-based catalyst loaded with nickel hydroxylate species can be prepared.

[0024] The silicon-based catalyst loaded with nickel hydroxylate species provided by the present invention effectively solves the problem that the metal is easily sintered and deactivated during a high-temperature reaction when using an ordinary silicon-based carrier.

[0025] The silicon-based catalyst loaded with nickel hydroxylate species provided by the invention can be used as a methane dry reforming catalyst, and has high catalytic activity and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 TEM images of the catalysts prepared in Examples 1 to 3 of the present invention, wherein A and D are TEM images of the Ni / SPP catalyst, B and E are TEM images of the Ni / SiO2 catalyst, and C and F are TEM images of the Ni / SBA-15 catalyst.

[0027] Figure 2 This is the infrared spectrum of the raw material SPP and the prepared Ni / SPP catalyst in Example 1 of the present invention.

[0028] Figure 3 It is the conversion rate of the methane dry reforming reaction catalyzed by each catalyst precursor prepared in Examples 1 to 3 of the present invention after reduction, wherein A is the conversion rate of methane and B is the conversion rate of carbon dioxide. DETAILED DESCRIPTION

[0029] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0030] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] Unless otherwise specified, the "room temperature" in the present invention refers to a temperature of 20±10°C.

[0034] The preparation steps of the self-supporting five-membered ring high silica zeolite (SPP) used in the embodiment of the present invention are as follows:

[0035] 13 g of tetrabutylammonium hydroxide solution (concentration of 25 wt.%, containing 12.5 mmol of tetrabutylammonium hydroxide) was mixed with 15.5 g of deionized water, and after stirring for 10 min, 8.32 g of tetraethyl orthosilicate (40 mmol) was added, and then the mixture was continuously stirred for 6 h. The obtained transparent solution was transferred to a stainless steel autoclave and treated at a constant temperature of 115°C for 48 h. After the constant temperature was completed, the material was taken out and centrifuged and washed 3 times, and then dried in an oven at 80°C. Finally, the sample was heated to 550°C at a rate of 10°C / min and calcined for 5 h to obtain SPP.

[0036] Example 1

[0037] 0.248 g of nickel nitrate (1.4 mmol) was added to 1.5 mL of deionized water, dissolved, added to 1 g of SPP carrier powder, stirred evenly, and then placed in an oven at 80 ° C for 12 hours. After drying, the temperature was raised from room temperature to 550 ° C in a muffle furnace at 10 ° C / min and maintained for 5 hours. The sample was annealed to room temperature to obtain a Ni / SPP catalyst precursor, and then reduced at 750 ° C, H2 / Ar (H2: 10 vol%) mixed atmosphere for 1 hour to obtain a Ni / SPP catalyst.

[0038] Example 2

[0039] 0.248g nickel nitrate (1.4mmol) was added to 1.5mL deionized water, dissolved and added to 1g commercial SiO2 carrier powder, stirred evenly, and then placed in an 80℃ oven for drying for 12h. After drying, the temperature was raised from room temperature to 550℃ in a muffle furnace at 10℃ / min and maintained for 5h. The sample was annealed to room temperature to obtain a Ni / SiO2 catalyst precursor, and then reduced at 750℃ in a H2 / Ar (H2: 10vol%) mixed atmosphere for 1h to obtain a Ni / SiO2 catalyst.

[0040] Example 3

[0041] 24 g of Pluronic P123 triblock polymer (PEO-PPO-PEO, Aldrich) was dissolved in a mixture of distilled water (650 mL) and hydrochloric acid (140 mL), and stirred at room temperature for 30 min until P123 was completely dissolved. Then, 55 mL of tetraethyl orthosilicate (TEOS) was added drop by drop under continuous stirring, and stirring was continued for 24 h. Then, the mixture was placed in an oven at 90 ° C for 24 h, the reaction product was filtered, washed, and dried at 80 ° C for 24 h. Finally, the temperature was raised to 550 ° C at a rate of 1 ° C / min and calcined for 6 h to obtain SBA-15.

[0042] 0.248g nickel nitrate (1.4mmol) was added to 1.5mL deionized water, dissolved and added to 1g SBA-15 carrier powder, stirred evenly, and then placed in an 80℃ oven for drying for 12h. After drying, the temperature was raised from room temperature to 550℃ in a muffle furnace at 10℃ / min and maintained for 5h. The sample was annealed to room temperature to obtain a Ni / SBA-15 catalyst precursor, and then reduced at 750℃ in a H2 / Ar (H2: 10vol%) mixed atmosphere for 1h to obtain a Ni / SBA-15 catalyst.

[0043] (1) Transmission electron microscopy experiment

[0044] After the image benchmark was calibrated by the probe forming spherical distortion corrector, the aberration-corrected high-angle annular dark-field scanning transmission electron micrograph (HAADF-STEM) was obtained. The equipment model was JEOL JEM-F200.

[0045] The TEM images of the catalysts prepared in Examples 1 to 3 are shown in Figure 1 , where A and D are TEM images of Ni / SPP catalyst, B and E are TEM images of Ni / SiO2 catalyst, and C and F are TEM images of Ni / SBA-15 catalyst.

[0046] from Figure 1It can be seen that the nickel particles on the Ni / SPP catalyst prepared in Example 1 of the present invention are evenly dispersed and have the smallest particle size.

[0047] (2) Pyridine infrared experiment

[0048] Pyridine was adsorbed on the raw material SPP or the prepared Ni / SPP catalyst of Example 1 at 150°C for 0.5 h. The final spectrum of the adsorbed saturated sample was between 4000 and 1200 cm -1 The infrared spectrum was scanned between the infrared bands with a spectral resolution of 4 and 32 scans were performed on a BrukerVERTEX 70 spectrometer. Figure 2 .

[0049] Depend on Figure 2 It can be seen that the Ni / SPP catalyst has a peak at 3742 cm -1 There is an obvious inverted peak at 1576 cm -1 A small shoulder peak appears at the α-H2O2 interface, indicating that Ni-OH forms a hydrogen bond with the support. This structure greatly increases the stability of the material.

[0050] (3) Application of catalytic methane dry reforming

[0051] The DRM catalytic tests were carried out in a fixed-bed quartz reactor (5 mm inner diameter) at atmospheric pressure;

[0052] In the experiment, 0.06 g of the Ni / SPP catalyst precursor, Ni / SiO2 catalyst precursor or Ni / SBA-15 catalyst precursor prepared in each embodiment was pressed into pellets, and then pellets with a size between 40 and 60 meshes were selected and loaded into the center of the reaction tube; then, at 750°C, H2 / Ar (H2: 10 vol%) mixed gas was introduced at a flow rate of 30 mL / min for 1 hour of in-situ reduction to obtain metallic active sites; after the reduction treatment was completed, the gas flow was switched to N2 for 10 minutes of purge to remove the residual H2 / Ar mixed gas; then, the methane dry reforming reaction test was carried out in the CH4-CO2 reaction gas (V CH4 :V CO2 :V N2 =1:1:1), with a total gas flow rate of 60 mL / min (GHSV 60000 mL·h -1 ·gcat -1 The gas composition was measured by two online gas chromatographs (GC, Fuli 9790II), which were equipped with one FID and two TCD detectors.

[0053] The conversion rate of the methane dry reforming reaction catalyzed by the catalyst precursors prepared in Examples 1 to 3 of the present invention after reduction is shown in FIG. Figure 3 , where A is the conversion rate of methane and B is the conversion rate of carbon dioxide.

[0054] from Figure 3 It can be seen that the Ni / SPP catalyst prepared by the technical solution of the present invention can maintain stable high activity when catalyzing methane dry reforming reaction.

[0055] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a silicon-based catalyst loaded with nickel hydroxylate species, characterized in that: The following steps are involved: Using Ni 2+ The silicon-based carrier is impregnated with a solution of A, the silicon-based carrier is taken out and dried after impregnation, calcined A, and then reduced to obtain the silicon-based catalyst loaded with nickel hydroxylate species; The silicon-based carrier is a self-supporting five-membered ring high-silicon zeolite, and the preparation steps include: Tetrabutylammonium hydroxide is dissolved in water, and ethyl orthosilicate is added. After mixing evenly, a solvent thermal reaction is carried out. The obtained solid product is dried and calcined to obtain the self-supporting five-membered ring high-silicon zeolite.

2. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The Ni-containing 2+ Ni in solution 2+ The usage ratio of the silica-based carrier is 1-3 mmol:1 g.

3. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The Ni-containing 2+ Ni in solution 2+ The concentration is 0.5~3mol / L.

4. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The calcination temperature of A is 500-600° C. and the calcination time is 5-6 hours.

5. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The reduction is carried out in a hydrogen atmosphere or a mixed atmosphere containing hydrogen, and the reduction temperature is 700-800°C.

6. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The molar ratio of the tetrabutylammonium hydroxide to the tetraethyl orthosilicate is 0.3-0.4:0.8-1.

2.

7. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 110-120° C. and the time is 45-50 hours.

8. The method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to claim 1, characterized in that: The calcination temperature of B is 500-600° C. and the calcination time is 54-6 hours.

9. A silicon-based catalyst loaded with nickel hydroxylate species obtained according to the method for preparing a silicon-based catalyst loaded with nickel hydroxylate species according to any one of claims 1 to 8.

10. Use of the silicon-based catalyst loaded with nickel hydroxylate species according to claim 9 in catalytic dry reforming of methane.

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