CN103223347B - Method for synthesis of silica loaded nickel-platinum catalyst by ultrasonic spray pyrolysis - Google Patents

Abstract

A method for synthesizing a silica-supported nickel-platinum catalyst by ultrasonic spray pyrolysis, step 1, preparation of a soluble compound solution containing metallic nickel-platinum; step 2, atomization of a soluble compound solution containing metallic nickel-platinum; step 3, tetrachloride Vaporization of silicon dioxide; step 4, pyrolysis reaction between atomized metal nickel platinum droplets and silicon tetrachloride vapor to generate nano-scale silicon dioxide, and at the same time, soluble compounds containing active nickel platinum form catalyst particle loading at high temperature On nano-silica; step five, catalyst collection and drying; the present invention solves the problem of expensive silica carrier and complex loading process, has simple synthesis process, and the obtained nano-silica-loaded nickel-platinum catalyst has high activity , good dispersion.

Description

Method for Synthesizing Silica-supported Nickel-Platinum Catalyst by Ultrasonic Spray Pyrolysis

technical field

The invention belongs to the technical field of catalyst preparation, and in particular relates to a method for synthesizing a silica-loaded nickel-platinum catalyst by an ultrasonic spray pyrolysis method.

Background technique

Nano-scale silica has a huge specific surface area, suitable pore structure distribution, good mechanical strength and chemical inertness, and can be used as a catalyst carrier. Silica-supported nickel-platinum metal catalysts can be used to catalyze various reactions such as hydrogenation, dehydrogenation, and hydrocracking.

The preparation of silica-supported active metal catalysts is currently mostly using the impregnation method, that is, the carrier silica is immersed in a solution containing active components and fully contacted, and then filtered, dried, roasted and activated to obtain the catalyst. The catalyst prepared by the impregnation method, the loaded active components are mainly distributed on the surface of the carrier, the distribution is uniform, and the utilization rate is high, which is very suitable for the preparation of noble metal catalysts such as Ni and Pt. Directly using shaped nano-silica as a carrier, although complex processes such as carrier molding and pretreatment are omitted, nano-scale silica is relatively expensive as a high-end nano-product.

The ultrasonic spray pyrolysis method uses ultrasonic waves to spray the solution, and undergoes pyrolysis reaction with another substance at high temperature. Due to the oscillating and dispersing effect of ultrasonic waves, the particle size of the ejected solution is about 5 μm, and reacts with high-temperature gas to synthesize nanomaterials with small aggregation, good dispersion, and high specific surface area. The principle of synthesizing nano-silica supported metal nickel and platinum by ultrasonic spray pyrolysis is that the soluble compound solution containing active metal nickel and platinum is ultrasonically oscillated and sprayed, and pyrolyzed with the silicon dioxide precursor at high temperature. Synthesis of Nano-Silica Supported Nickel-Platinum Catalysts. In the reaction, the polysilicon waste silicon tetrachloride (SiCl ₄ ) is used to replace the traditional tetraethyl silicate (TEOS) as the precursor of silicon dioxide, which can reduce the cost and realize the reuse of resources. There are no relevant patents and research reports at home and abroad on the method of synthesizing nano-silica-supported nickel-platinum catalysts by ultrasonic spray pyrolysis.

Contents of the invention

In order to overcome the defects of the above-mentioned prior art, the object of the present invention is to provide a method for synthesizing silica-supported nickel-platinum by ultrasonic spray pyrolysis in view of the shortcomings of the impregnation method, such as the expensive nano-silica catalytic carrier and the complicated carrier molding process. The catalyst method solves the problems of expensive silicon dioxide carrier and complex loading process, has the advantages of simple synthesis process, and the obtained nanometer silicon dioxide loaded nickel-platinum catalyst has high activity and good dispersibility.

In order to achieve the above object, technical scheme of the present invention is:

The method for the synthesis of silicon dioxide-supported nickel-platinum catalyst by ultrasonic spray pyrolysis method comprises the following steps:

Step 1. Preparation of a soluble compound solution containing metallic nickel and platinum: the active metal is nickel, platinum or a combination of the two in any proportion, and a soluble compound solution containing metallic nickel and platinum with a mass concentration of 0.2 to 2% is prepared;

Step 2. Atomization of the soluble compound solution containing metallic nickel and platinum: use an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, and the atomization rate is 0.4mL/min, and the soluble compound solution containing metallic nickel and platinum Atomized into droplets with an average particle size of 5 μm and sprayed into the pyrolysis reactor;

Step 3, vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride is first purified through distillation equipment, then silicon tetrachloride is heated to more than 60 ℃ for vaporization, and by carrier gas Bring out;

Step 4: The atomized metal nickel-platinum droplets and silicon tetrachloride vapor undergo a pyrolysis reaction: the silicon tetrachloride vapor and the atomized nickel-platinum droplets are sprayed into the pyrolysis reactor, and the silicon tetrachloride gas The molar ratio of the nickel and platinum droplets is 1:10 to 1:50, and the reaction is carried out at a temperature of 200 to 500 ° C. The silicon tetrachloride gas and the micron-sized droplets undergo a hydrolysis reaction to form nano-sized silicon dioxide. The remaining water in the droplet is evaporated to dryness, and at the same time, the soluble compound containing active nickel and platinum forms catalyst particles at high temperature and supports them on the nano-silica.

Step 5. Catalyst collection and drying: the nickel-platinum catalyst powder supported by nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product.

Advantage of the present invention:

(1) Using the ultrasonic spray pyrolysis method, the preparation of nano-silica carrier and the loading of active components can be realized in one step. The process is simple, and the obtained catalyst has high activity and good dispersion.

(2) The silicon dioxide precursor uses silicon tetrachloride, a by-product of polysilicon, to replace the commonly used ethyl orthosilicate, so as to reduce costs and realize resource reuse.

(3) Catalysts with different catalytic efficiencies can be obtained by changing the concentration of the soluble chemical component solution containing nickel and platinum.

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments.

Embodiment one

The method for synthesizing silica-supported nickel-platinum catalyst by ultrasonic spray pyrolysis method specifically comprises the following steps:

Step 1. Preparation of soluble compound solution containing active metal: Dissolve Ni(OH) ₂ in 0.4 mol/L hydrochloric acid solution to form NiCl ₂ solution, ensuring that the mass fraction of nickel is 1%.

Step 2. Atomization of NiCl ₂ solution: Use an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, and the atomization rate is 0.4mL/min to atomize the NiCl ₂ solution into droplets with an average particle size of 5 μm into the pyrolysis reactor.

Step 3, the vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator to vaporize after being purified by distillation equipment, silicon tetrachloride injection speed is 0.2mL/min.

Step 4, NiCl ₂ liquid droplets and silicon tetrachloride vapor generation pyrolysis reaction: silicon tetrachloride vapor and NiCl ₂ liquid droplets are sprayed into pyrolysis reactor, the mol ratio of silicon tetrachloride gas and nickel-platinum liquid droplet is 1:10～1:50, react at 300°C, silicon tetrachloride gas and micron-sized droplets undergo a hydrolysis reaction to generate nano-sized silicon dioxide, the remaining water in the droplets is evaporated to dryness, and NiCl ₂ at high temperature The formation of Ni catalyst particles loaded on the nano-silica.

Step 5. Catalyst collection and drying: Nano silica-supported Ni catalyst powder is deposited in the collector, and the powder is taken out and dried at 200°C for 2 hours to obtain the product.

The catalyst was tested and characterized. The BET specific surface area was 245m ² /g, the total pore volume was 0.18mL/g, and the XRF data showed that the mass percentage of nickel/silicon dioxide was 22%.

Embodiment two

The method for synthesizing silica-supported nickel-platinum catalyst by ultrasonic spray pyrolysis method specifically comprises the following steps:

Step 1. Preparation of soluble compound solution containing active metal: Dissolve chloroplatinic acid (H ₂ PtCl ₆ ) in pure water to ensure that the mass fraction of platinum is 1%.

Step 2. Atomization of the H ₂ PtCl ₆ solution: using an ultrasonic nebulizer with a power of 200W and a transducer frequency of 1.7MHz, the atomization rate is 0.4mL/min, and the H ₂ PtCl ₆ solution is atomized into an average particle size of 5 μm droplets are sprayed into the pyrolysis reactor.

Step 3, the vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator to vaporize after being purified by distillation equipment, silicon tetrachloride injection speed is 0.2mL/min.

Step 4, pyrolysis reaction of H ₂ PtCl ₆ droplets and silicon tetrachloride vapor: silicon tetrachloride vapor and H ₂ PtCl ₆ droplets are sprayed into the pyrolysis reactor, silicon tetrachloride gas and nickel platinum droplets The molar ratio is 1:10 to 1:50, and the reaction is carried out at 300°C. Silicon tetrachloride gas undergoes hydrolysis reaction with micron-sized droplets to generate nano-sized silicon dioxide. The remaining water in the droplets is evaporated to dryness, and H ₂ PtCl ₆ forms Pt catalyst particles at high temperature to be loaded on the nano-sized silicon dioxide.

Step 5. Catalyst collection and drying: the Pt catalyst powder loaded on nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product.

The catalyst was tested and characterized: the BET specific surface area was 275m ² /g, the total pore volume was 0.37mL/g, and the mass percentage of platinum/silicon oxide was 24% as measured by XRF.

Embodiment three

The method for synthesizing silica-supported nickel-platinum catalyst by ultrasonic spray pyrolysis method specifically comprises the following steps:

Step 1. Preparation of a soluble compound solution containing active metal: a NiCl ₂ solution with a mass fraction of Ni of 0.5% and a solution of H ₂ PtCl ₆ with a mass fraction of Pt of 0.5% were prepared.

Step 2. Atomization of the mixed solution containing Ni/Pt active components: using an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, the atomization rate is 0.4mL/min, and the Ni/Pt active solution is atomized into The droplets with an average particle size of 5 μm are sprayed into the pyrolysis reactor.

Step 3, the vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator to vaporize after being purified by distillation equipment, silicon tetrachloride injection speed is 0.2mL/min.

Step 4, Ni/Pt active solution droplets and silicon tetrachloride vapor pyrolysis reaction: silicon tetrachloride vapor and Ni/Pt active solution droplets are sprayed into the pyrolysis reactor, silicon tetrachloride gas and nickel platinum The molar ratio of the droplets is 1:10～1:50, and the reaction is carried out at 300°C. The silicon tetrachloride gas and the micron-sized droplets undergo a hydrolysis reaction to form nano-sized silicon dioxide, and the remaining water in the droplets is evaporated to dryness. , NiCl ₂ /H ₂ PtCl ₆ forms nickel-platinum catalyst particles supported on nano-silica at high temperature.

Step 5. Catalyst collection and drying: the nickel-platinum catalyst powder supported by nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product.

The catalyst was tested and characterized: the BET specific surface area was 230m ² /g, and the total pore volume was 0.53mL/g.

Claims (4)

1. the method for ultrasonic spray pyrolysis synthetic silica supported nickel-platinum catalyst, is characterized in that, comprises the following steps: Step 1. Preparation of a soluble compound solution containing nickel and platinum: the active metal is nickel, platinum or a combination of the two in any proportion, and a soluble compound solution containing nickel and platinum with a mass concentration of 0.2-2% is prepared; Step 2. Atomization of the soluble compound solution containing metallic nickel and platinum: use an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, and the atomization rate is 0.4mL/min, and the soluble compound solution containing metallic nickel and platinum Atomized into droplets with an average particle size of 5 μm and sprayed into the pyrolysis reactor; Step 3, vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride is first purified through distillation equipment, then silicon tetrachloride is heated to more than 60 ℃ for vaporization, and by carrier gas Bring out; Step 4: The atomized metal nickel-platinum droplets and silicon tetrachloride vapor undergo a pyrolysis reaction: the silicon tetrachloride vapor and the atomized nickel-platinum droplets are sprayed into the pyrolysis reactor, and the silicon tetrachloride gas The molar ratio of the nickel and platinum droplets is 1:10 to 1:50, and the reaction is carried out at a temperature of 200 to 500 ° C. The silicon tetrachloride gas and the micron-sized droplets undergo a hydrolysis reaction to form nano-sized silicon dioxide. The remaining water in the drop is evaporated to dryness, and at the same time, the soluble compound containing active nickel and platinum forms catalyst particles at high temperature and is loaded on the nano-silica; Step 5. Catalyst collection and drying: the nickel-platinum catalyst powder supported by nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product. 2. the method for ultrasonic spray pyrolysis synthetic silica supported nickel-platinum catalyst according to claim 1, is characterized in that, comprises the following steps: step 1, the preparation of the soluble compound solution containing active metal: Ni(OH ) ₂ is dissolved in the hydrochloric acid solution of 0.4mol/L, forms NiCl ₂ solution, the mass fraction that guarantees nickel is 1%; Step 2. Atomization of NiCl ₂ solution: Use an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, and the atomization rate is 0.4mL/min to atomize the NiCl ₂ solution into droplets with an average particle size of 5 μm into the pyrolysis reactor; Step 3, vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator after being purified by distillation equipment and vaporizes, silicon tetrachloride injection speed is 0.2mL/min; Step 4, NiCl ₂ liquid droplets and silicon tetrachloride vapor generation pyrolysis reaction: silicon tetrachloride vapor and NiCl ₂ liquid droplets are sprayed into pyrolysis reactor, the mol ratio of silicon tetrachloride gas and nickel-platinum liquid droplet is 1:10～1:50, react at 300°C, silicon tetrachloride gas and micron-sized droplets undergo a hydrolysis reaction to generate nano-sized silicon dioxide, the remaining water in the droplets is evaporated to dryness, and NiCl ₂ at high temperature Forming Ni catalyst particles supported on nano-silica; Step 5. Catalyst collection and drying: Nano silica-supported Ni catalyst powder is deposited in the collector, and the powder is taken out and dried at 200°C for 2 hours to obtain the product. 3. the method for the synthesis of silicon dioxide supported nickel-platinum catalyst by ultrasonic spray pyrolysis according to claim 1, is characterized in that, step 1, the preparation of the soluble compound solution containing active metal: chloroplatinic acid (H ₂ PtCl ₆ ) dissolved in pure water, ensuring that the mass fraction of platinum is 1%; Step 2. Atomization of the H ₂ PtCl ₆ solution: using an ultrasonic nebulizer with a power of 200W and a transducer frequency of 1.7MHz, the atomization rate is 0.4mL/min, and the H ₂ PtCl ₆ solution is atomized into an average particle size of 5μm droplets are sprayed into the pyrolysis reactor; Step 3, vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator after being purified by distillation equipment and vaporizes, silicon tetrachloride injection speed is 0.2mL/min; Step 4, pyrolysis reaction of H ₂ PtCl ₆ droplets and silicon tetrachloride vapor: silicon tetrachloride vapor and H ₂ PtCl ₆ droplets are sprayed into the pyrolysis reactor, silicon tetrachloride gas and nickel platinum droplets The molar ratio is 1:10～1:50, and the reaction is carried out at 300°C. The silicon tetrachloride gas and the micron-sized droplets undergo a hydrolysis reaction to generate nano-sized silicon dioxide. The remaining water in the droplets is evaporated to dryness, and the H ₂ PtCl ₆ forms Pt catalyst particles supported on nano-silica at high temperature; Step 5. Catalyst collection and drying: the Pt catalyst powder loaded on nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product. 4. the method for synthesizing silicon dioxide supported nickel-platinum catalyst by ultrasonic spray pyrolysis method according to claim 1, is characterized in that, step 1, the preparation of the soluble compound solution containing active metal: preparation Ni massfraction is 0.5% NiCl ₂ solution and Pt mass fraction are 0.5% H ₂ PtCl ₆ solution; Step 2. Atomization of the mixed solution containing Ni/Pt active components: using an ultrasonic atomizer with a power of 200W and a transducer frequency of 1.7MHz, the atomization rate is 0.4mL/min, and the Ni/Pt active solution is atomized into The droplets with an average particle size of 5 μm are sprayed into the pyrolysis reactor; Step 3, vaporization of silicon tetrachloride: adopt polysilicon by-product silicon tetrachloride as raw material, silicon tetrachloride enters evaporator after being purified by distillation equipment and vaporizes, silicon tetrachloride injection speed is 0.2mL/min; Step 4, Ni/Pt active solution droplets and silicon tetrachloride vapor pyrolysis reaction: silicon tetrachloride vapor and Ni/Pt active solution droplets are sprayed into the pyrolysis reactor, silicon tetrachloride gas and nickel platinum The molar ratio of the droplets is 1:10～1:50, and the reaction is carried out at 300°C. The silicon tetrachloride gas and the micron-sized droplets undergo a hydrolysis reaction to form nano-sized silicon dioxide, and the remaining water in the droplets is evaporated to dryness. , NiCl ₂ /H ₂ PtCl ₆ forms nickel-platinum catalyst particles supported on nano-silica at high temperature; Step 5. Catalyst collection and drying: the nickel-platinum catalyst powder supported by nano-silica is deposited in the collector, and the powder is taken out and dried at 200° C. for 2 hours to obtain the product.