阅读说明：本技术 以纳米金刚石为载体的非金属修饰铂系催化剂的制备方法 (Preparation method of non-metal modified platinum catalyst with nano-diamond as carrier ) 是由 魏伟胜 刘传亮 刘杰 郑辉东 王屹鸣 王皓月 汪义香 于 2021-03-11 设计创作，主要内容包括：本发明公开了一种以纳米金刚石为载体的非金属修饰铂系催化剂的制备方法。其是采用非金属前驱体溶液对纳米金刚石进行浸渍,然后在惰性气体下进行高温煅烧,再采用含铂前驱体溶液对其进行铂负载,最后进行还原,得到非金属硼-氮、硼-磷双修饰或硼-氮-磷三修饰的铂系催化剂。本发明所制备的催化剂在低碳烷烃脱氢催化反应中具有高活性以及高选择性,且相比金属修饰的Pt系催化剂,本发明所制备的非金属修饰的Pt系催化剂合成过程简单易行,并大大降低了制造成本,可为今后开发出高性能低碳烷烃脱氢催化剂提供新的引导方向。(The invention discloses a preparation method of a non-metal modified platinum catalyst taking nano-diamond as a carrier. The method comprises the steps of dipping the nano-diamond by adopting a non-metal precursor solution, then carrying out high-temperature calcination under inert gas, carrying out platinum loading on the nano-diamond by adopting a platinum-containing precursor solution, and finally carrying out reduction to obtain the non-metal boron-nitrogen, boron-phosphorus double-modified or boron-nitrogen-phosphorus triple-modified platinum-based catalyst. The catalyst prepared by the invention has high activity and high selectivity in the low-carbon alkane dehydrogenation catalytic reaction, and compared with a metal modified Pt catalyst, the non-metal modified Pt catalyst prepared by the invention has simple and easy synthesis process, greatly reduces the manufacturing cost, and can provide a new guide direction for developing a high-performance low-carbon alkane dehydrogenation catalyst in the future.)

1. A method for preparing a non-metal modified platinum catalyst with nano diamond as a carrier is characterized by comprising the following steps: dipping the nano-diamond by adopting a non-metal precursor solution, then calcining at high temperature under inert gas, carrying out platinum loading on the nano-diamond by adopting a platinum-containing precursor solution, and finally reducing to obtain the non-metal modified platinum-based catalyst;

the nonmetal is selected from at least one of boron, nitrogen and phosphorus, wherein the doping amount of boron is 0.1-10% of the weight of the catalyst, and the doping amounts of nitrogen and phosphorus are 0-10% of the weight of the catalyst; the loading amount of the platinum is 0.1-10% of the weight of the catalyst.

2. The method of claim 1, wherein: the precursor of boron is one or more of simple substance boron, boric acid, sodium metaborate, potassium metaborate and borax decahydrate;

the precursor of the nitrogen is one or more of ammonia gas, ammonium hydroxide, ammonium nitrate, ammonium chloride, melamine, dopamine hydrochloride and urea;

the phosphorus precursor is one or more of phytic acid, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, triethyl phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate.

3. The method of claim 1, wherein: the purity of the used nano diamond is 93-96.5%, and the particle size is 20-250 nm.

4. The method of claim 1, wherein: the inert gas is argon or nitrogen.

5. The method of claim 1, wherein: the high-temperature calcination is carried out at the temperature of 600-1500 ℃ for 0.1-10 h.

6. The method of claim 1, wherein: the platinum-containing precursor is platinum nitrate, chloroplatinic acid, potassium chloroplatinate, dichlorotetramine platinum or acetylacetone platinum.

7. The method of claim 1, wherein: the non-metal precursor solution or the platinum-containing precursor solution is prepared by adopting one or more of water, methanol, ethanol, formaldehyde and acetone as a solvent.

8. The method of claim 1, wherein: the platinum load is treated by ultrasonic wave and then stirred and dipped.

9. The method of claim 1, wherein: the reduction is carried out by adopting a reducing agent or reducing atmosphere hydrogen; the reducing agent is selected from any one of ethylene glycol, C1-C3 carboxylic acid and C1-C3 sodium carboxylate.

10. The application of the non-metal doped platinum catalyst prepared by the method of claim 1 in the dehydrogenation reaction of light alkane, which is characterized in that: the temperature of the dehydrogenation reaction is 500-650 ℃, the pressure is 0.1-0.5 MPa, and the reaction time is 0.1-20 h.

Technical Field

The invention belongs to the field of preparation of low-carbon alkane dehydrogenation catalysts, and particularly relates to a preparation method of a non-metal modified platinum-based catalyst with nano-diamond as a carrier.

Background

With the shale gas revolution in the United states, the price of propane on the market is gradually reduced, and compared with the traditional method for producing propylene by naphtha cracking and petroleum catalytic cracking, the method for directly dehydrogenating propane to prepare propylene has a great development prospect. The conventional propane direct dehydrogenation catalyst is a chromium-based catalyst, but is gradually replaced by a platinum-based catalyst due to environmental pollution problems of chromium metal. The direct dehydrogenation of propane to propylene is a reversible reaction with increased number of molecules and strong heat absorption, so low pressure and high temperature are reaction conditions favorable for the reaction. In addition to the tendency of platinum metal agglomeration caused by such high temperature reaction conditions, the deep cracking of propane not only reduces the selectivity of propylene but also generates carbon deposits to cover active centers, and these adverse factors all result in the reduction of the catalytic performance of the platinum-based catalyst.

The platinum catalyst usually uses molecular sieve and alumina as carriers, and adds a proper amount of auxiliary agent to improve the catalytic performance, and these catalysts have been used in industrial production. However, the molecular sieve and the alumina have strong acidity, which is easy to cause deep cracking of propane and further reduce the activity of the catalyst. In order to avoid the above problems, carbon materials have been increasingly studied as platinum-based catalyst supports. The highly graphitized carbon material can change the physical and chemical properties of the platinum metal, thereby improving the catalytic activity and propylene selectivity thereof.

Nano diamondAs a carbon material carrier, not only can defect sites fix platinum metal under the action of high temperature, but also the generated graphite carbon can generate electron transfer, thereby improving the electron density of the platinum metal, promoting the desorption of propylene and preventing deep dehydrogenation. Zhang et al (J. Zhang, X. Cai, K. -H. Wu, et al, Nanodiamond-Core-Reinforced, Graphene-Shell-Immobilized Platinum Nanoparticles as a high Active Catalyst for the Low-Temperature dehydration of n-butyl, Chemcatchem, 10 (2018) 520-524.) load Platinum on a Platinum-carrying substrate with sp²/sp³The carbon-hybridized nano-diamond carrier has higher catalytic activity in catalyzing dehydrogenation of n-butane than that of platinum loaded on alumina. Wang et al (R. Wang, X. Sun, B. Zhang, et al. Hybrid nanocarbon as a catalyst for direct conversion of propane: formation of an active and a selective core-shell sp²/sp³nanocomposite structure, Chemistry, 20 (2014) 6324-6331) nanodiamonds not loaded with any metal were treated in an inert gas atmosphere under different high temperature conditions for a certain period of time, and were found to exhibit the best catalytic activity in the direct dehydrogenation reaction of propane after being treated at 1100 ℃.

Disclosure of Invention

The invention aims to provide a preparation method of a non-metal doped platinum catalyst taking nano-diamond as a carrier, which adopts different non-metal precursors to modify the nano-diamond, then carries out platinum loading, and can show high catalytic activity, high selectivity and good stability when the obtained catalyst is applied to dehydrogenation catalytic reaction of low-carbon alkane.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a non-metal modified platinum catalyst with nano-diamond as a carrier comprises the steps of dipping the nano-diamond by adopting a non-metal precursor solution, then carrying out high-temperature calcination under inert gas, carrying out platinum loading on the nano-diamond by adopting a platinum-containing precursor solution, and finally carrying out reduction to obtain the non-metal modified platinum catalyst; the nonmetal is selected from at least one of boron, nitrogen and phosphorus, wherein the doping amount of boron is 0.1-10% of the weight of the catalyst, and the doping amounts of nitrogen and phosphorus are 0-10% of the weight of the catalyst; the loading amount of the platinum is 0.1-10% of the weight of the catalyst.

The precursor of boron is one or more of simple substance boron, boric acid, sodium metaborate, potassium metaborate and borax decahydrate; the precursor of the nitrogen is one or more of ammonia gas, ammonium hydroxide, ammonium nitrate, ammonium chloride, melamine, dopamine hydrochloride and urea; the phosphorus precursor is one or more of phytic acid, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, triethyl phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate.

The purity of the used nano diamond is 93-96.5%, and the particle size is 20-250 nm.

The inert gas is argon or nitrogen.

The high-temperature calcination is carried out at the temperature of 600-1500 ℃ for 0.1-10 h.

The platinum-containing precursor is platinum nitrate, chloroplatinic acid, potassium chloroplatinate, dichlorotetramine platinum or acetylacetone platinum.

The non-metal precursor solution or the platinum-containing precursor solution is prepared by adopting one or more of water, methanol, ethanol, formaldehyde and acetone as a solvent.

The platinum load is prepared by firstly adopting ultrasonic treatment for 0.5-10h at normal temperature and then stirring for 0.5-10h for impregnation.

The reduction is carried out by adopting a reducing agent or reducing atmosphere hydrogen; the reducing agent is selected from any one of ethylene glycol, C1-C3 carboxylic acid and C1-C3 sodium carboxylate.

The nonmetal-doped platinum-based catalyst prepared by the method can be used for dehydrogenation of low-carbon alkane, the temperature of the dehydrogenation is 500-650 ℃, the pressure is 0.1-0.5 MPa, and the reaction time is 0.1-20 h.

The invention has the following remarkable advantages:

the invention adopts the nano diamond carbon material as the carrier, can effectively overcome the problem of deep cracking of propane caused by strong acidity of the molecular sieve and the alumina carrier, improves the selectivity of the product propylene, and can obviously change the physical and chemical properties of platinum metal so as to improve the catalytic performance of the platinum metal.

Compared with a metal auxiliary agent, the nonmetal auxiliary agent used in the invention can reduce the manufacturing cost of the catalyst and solve the problem of metal pollution, is simple and easy to operate, has high activity and high selectivity, and can provide a new reference direction for the low-carbon alkane dehydrogenation catalyst.

Drawings

FIG. 1 is an X-ray diffraction pattern of the catalysts obtained in examples 1 to 3 and comparative example 4.

Detailed Description

The invention adopts a nano diamond carbon material with the particle size of 20-250 nm and the weight of 93-96.5 wt% as a platinum catalyst carrier, and the nano diamond carbon material is applied to dehydrogenation catalytic reaction of low-carbon alkane through non-metal modification. The method for modifying the nano-diamond by the nonmetal comprises the following steps: the nano-diamond is firstly impregnated by adopting a corresponding non-metal precursor solution, then is calcined at high temperature under inert gas, and then is loaded and reduced by platinum. The non-metal modification adopts boron-nitrogen and boron-phosphorus double modification and boron-nitrogen-phosphorus triple modification.

The present invention will be described in further detail with reference to examples, but the present invention is not limited thereto.

The preparation method of the precursor solution of boron, nitrogen and phosphorus comprises the following steps: preparing a boron-containing solution by using boric acid as a boron precursor and absolute ethyl alcohol as a solvent, wherein the concentration of boron is 5 mg/mL; preparing a nitrogen-containing solution by using melamine as a nitrogen precursor and formaldehyde as a solvent, wherein the concentration of nitrogen is 5 mg/mL; and (3) preparing a phosphorus-containing solution by using ammonium dihydrogen phosphate as a phosphorus precursor and deionized water as a solvent, wherein the concentration of phosphorus is 5 mg/mL.

The preparation method of the precursor solution of the platinum comprises the following steps: the platinum-containing solution is prepared by taking chloroplatinic acid hexahydrate as a platinum precursor and absolute ethyl alcohol as a solvent, wherein the concentration of platinum is 5 mg/mL.

Example 1:

taking 0.5g of nano-diamond with the particle size of about 50nm, adding 5mL of boron-containing solution, 5mL of nitrogen-containing solution and 5mL of water, magnetically stirring for 1h, raising the temperature to 110 ℃, stirring to dry, and drying at 110 ℃ overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the load capacity of boron, the load capacity of nitrogen and the load capacity of platinum in the obtained catalyst are respectively marked as A, wherein the load capacity of boron is 5wt%, the load capacity of nitrogen is 5wt% and.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions indicated above, and the performance data within 10h of the reaction are shown in Table 1.

Table 1 performance data for the catalyst prepared in example 1 in propane dehydrogenation

Example 2:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of boron-containing solution, 5mL of phosphorus-containing solution and 5mL of formaldehyde; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the obtained catalyst has the load capacity of 5wt% of boron, 5wt% of phosphorus and 5wt% of platinum and is marked as B.

0.2g of the catalyst prepared above was taken and packed in a microreaction device as a volume fraction of propane5 percent of mixture of propane and nitrogen is used as reaction raw material, the temperature is 600 ℃, the pressure is 0.1MPa, and the propane feeding mass space velocity is 1.8h^-1The dehydrogenation reaction was carried out under the conditions specified in (1), and the performance data within 10h of the reaction are shown in Table 2.

Table 2 performance data for the catalyst prepared in example 2 in propane dehydrogenation

Example 3:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of boron-containing solution, 5mL of nitrogen-containing solution and 5mL of phosphorus-containing solution; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, and reduction is carried out for 1h under the atmosphere of hydrogen at 580 ℃, wherein the load capacity of boron in the obtained catalyst is 5wt%, the load capacity of nitrogen is 5wt%, the load capacity of phosphorus is 5wt%, and the load capacity of platinum is 5wt%, which is marked as C.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions specified in (1), and the performance data within 10h of the reaction are shown in Table 3.

Table 3 performance data for the catalyst prepared in example 3 in the propane dehydrogenation reaction

Comparative example 1:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of boron-containing solution, 5mL of formaldehyde and 5mL of water; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the load capacity of boron and the load capacity of platinum in the obtained catalyst are respectively 5wt% and marked as D.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and the conversion of propane was 23.32% and the selectivity of propylene was 89.05% at 0.1 hour of the reaction.

Comparative example 2:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of absolute ethyl alcohol, 5mL of nitrogenous solution and 5mL of water; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the obtained catalyst has the nitrogen loading of 5wt% and the platinum loading of 5wt%, and is marked as E.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and 0.1 hour of the reaction, the conversion of propane was 16.52% and the selectivity of propylene was 77.86%.

Comparative example 3:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of absolute ethyl alcohol, 5mL of phosphorus-containing solution and 5mL of formaldehyde; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3g of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the load capacity of phosphorus and the load capacity of platinum in the obtained catalyst are respectively 5wt% and marked as F.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and the conversion of propane was 16.50% and the selectivity of propylene was 87.34% at 0.1 h.

Comparative example 4:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of absolute ethyl alcohol, 5mL of deionized water and 5mL of formaldehyde; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; then 0.3G of ground sample is taken, 3mL of absolute ethyl alcohol solution of chloroplatinic acid and 7mL of absolute ethyl alcohol are added, magnetic stirring is carried out for 1h, ultrasonic treatment is carried out for 3h, stirring is carried out for 3h, then the temperature is adjusted to 110 ℃, stirring is carried out until the mixture is dry, drying is carried out at 80 ℃ overnight, reduction is carried out for 1h under the hydrogen atmosphere at 580 ℃, and the load capacity of platinum in the obtained catalyst is 5wt%, which is marked as G.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and 0.1 hour of the reaction, the conversion of propane was 12.90% and the selectivity of propylene was 89.88%.

Comparative example 5:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of boron-containing solution, 5mL of formaldehyde and 5mL of water; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; and then taking 0.3g of ground sample, adding 10mL of absolute ethyl alcohol solution, magnetically stirring for 1H, carrying out ultrasonic treatment for 3H, then stirring for 3H, then adjusting the temperature to 110 ℃, stirring to dry, drying at 80 ℃ overnight, and reducing for 1H at 580 ℃ in a hydrogen atmosphere, wherein the load amount of boron in the obtained catalyst is 5wt%, and is marked as H.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and 0.1 hour of the reaction, the conversion of propane was 8.08% and the selectivity of propylene was 86.91%.

Comparative example 6:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of nitrogenous solution, 5mL of ethanol and 5mL of water; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; and then taking 0.3g of ground sample, adding 10mL of absolute ethyl alcohol solution, magnetically stirring for 1h, carrying out ultrasonic treatment for 3h, then stirring for 3h, then adjusting the temperature to 110 ℃, stirring to dry, drying at 80 ℃ overnight, and reducing for 1h at 580 ℃ in a hydrogen atmosphere, wherein the loading amount of nitrogen in the obtained catalyst is 5wt%, and is marked as I.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and the conversion of propane was 5.32% and the selectivity of propylene was 84.21% at 0.1 hour.

Comparative example 7:

taking 0.5g of nano-diamond with the particle size of about 50nm, and adding 5mL of phosphorus-containing solution, 5mL of ethanol and 5mL of formaldehyde; magnetically stirring for 1h, heating to 110 deg.C, stirring to dry, and drying at 110 deg.C overnight; transferring the dried sample into a tubular furnace, calcining at the high temperature of 1100 ℃ for 4h in the nitrogen atmosphere, and fully grinding the calcined sample; and then taking 0.3g of ground sample, adding 10mL of absolute ethyl alcohol solution, magnetically stirring for 1h, carrying out ultrasonic treatment for 3h, then stirring for 3h, then adjusting the temperature to 110 ℃, stirring to dry, drying at 80 ℃ overnight, and reducing for 1h at 580 ℃ in a hydrogen atmosphere, wherein the load amount of phosphorus in the obtained catalyst is 5wt%, and is marked as J.

Taking 0.2g of the catalyst prepared above, filling the catalyst in a micro-reactor, taking a mixture of propane and nitrogen with the volume fraction of propane of 5% as a reaction raw material, and feeding propane at the temperature of 600 ℃, the pressure of 0.1MPa and the mass space velocity of propane for 1.8h^-1The dehydrogenation reaction was carried out under the conditions of (1) and the conversion of propane was 7.56% and the selectivity of propylene was 90.21% in 0.1 hour of the reaction.

The catalytic performance of the catalyst obtained in the comparative example and the catalyst obtained in the comparative example for directly dehydrogenating to prepare propylene can be found that the effect of re-loading platinum on the nano-diamond modified by boron-nitrogen and boron-phosphorus double modification and boron-nitrogen-phosphorus triple modification is better than that of re-loading platinum on the nano-diamond modified by boron, nitrogen and phosphorus single modification.

The XRD patterns of the catalysts obtained in comparative example and comparative example 4 revealed that boron-nitrogen and boron-phosphorus double-modified and boron-nitrogen-phosphorus triple-modified nanodiamond re-supported platinum introduced new active species and some specific structures, such as P = O group, BN structure and PtP, compared to unmodified directly supported platinum₂Species, etc., which may be the main cause of a large increase in catalyst performance.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.