Propane dehydrogenation catalyst, preparation method and application thereof
The propane dehydrogenation catalyst with two active sites, prepared by in-situ encapsulation and impregnation methods, solves the problems of low activity and easy deactivation of existing catalysts, and realizes efficient propylene production.
Patent Information
- Application Number
- CN202410580665.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-11
- Publication Date
- 2025-11-11
AI Technical Summary
Existing catalysts for the dehydrogenation of propane from carbon dioxide to propylene have low activity and are prone to deactivation, and their propane conversion and propylene selectivity are low, which limits the industrial application of this technology.
A first metal@molecular sieve was prepared by in-situ encapsulation, and Pt metal was loaded onto the surface of the molecular sieve by impregnation to form a propane dehydrogenation catalyst with two active sites, which was used to catalyze the carbon dioxide oxidation of propane dehydrogenation reaction.
It improves catalyst activity and propylene yield, reduces catalyst deactivation rate, and provides a green and economical solution for propylene production.
Smart Images
Figure CN120920046A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of dehydrogenation catalyst material preparation technology, and in particular relates to a propane dehydrogenation catalyst, its preparation method and its application. Background Technology
[0002] Propylene, as a key chemical raw material, plays a crucial role in chemical production. Its main uses include the production of high-value-added chemicals such as polypropylene, propylene oxide, and acrylonitrile. With the continued growth of the global economy, the demand for propylene is increasing at a rate of approximately 5% annually, currently reaching about 90 million tons worldwide. However, existing propylene production methods, primarily through naphtha cracking to produce ethylene with propylene co-production and catalytic cracking, cannot meet the ever-growing market demand.
[0003] While naphtha cracking for ethylene and propylene co-production is currently the most important method for propylene production, its limitations stem from the nature of the cracking process. Optimizing process conditions to increase propylene yield can negatively impact the production of other products. Furthermore, catalytic cracking for propylene production, although also an important route, similarly faces issues of efficiency and selectivity.
[0004] With the advent of the "shale gas revolution," abundant and inexpensive propane resources have provided new possibilities for propylene production. Although traditional direct propane dehydrogenation technology is theoretically feasible, its strong endothermic nature requires operation at temperatures above 550°C. Such conditions not only place higher demands on equipment but also lead to rapid catalyst deactivation and thermal decomposition of propylene, limiting the widespread application of this technology.
[0005] To address the aforementioned issues, propane oxidative dehydrogenation using CO2 as an oxidant has emerged as a promising alternative. This technology can be carried out under relatively mild conditions, effectively mitigating the limitations of thermodynamic equilibrium, and can convert CO2 into valuable chemicals, achieving resource utilization of CO2 and exhibiting environmentally friendly characteristics. However, currently reported catalysts for the oxidative dehydrogenation of propane to propylene using carbon dioxide generally exhibit low activity, are prone to deactivation, and result in low propylene yields, which has become a major obstacle to the industrial application of this technology.
[0006] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention
[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a propane dehydrogenation catalyst, a preparation method thereof, and its application, to solve the problems of low activity and easy deactivation of catalysts used for propane dehydrogenation by carbon dioxide oxidation in the prior art, as well as the problems of low conversion rate of propane and low selectivity of propylene in the dehydrogenation catalysts of the prior art.
[0008] To achieve the above and other related objectives, the present invention provides a method for preparing a propane dehydrogenation catalyst, the method comprising the following steps:
[0009] S1. The first metal@molecular sieve was prepared by in-situ encapsulation method;
[0010] S2. Stir and mix the Pt precursor aqueous solution and the non-precious metal precursor aqueous solution to obtain a metal precursor aqueous solution;
[0011] S3. The first metal@molecular sieve is added to the aqueous solution of the metal precursor as a support, stirred evenly at room temperature, and then vacuum dried at 50℃~120℃ to obtain the catalyst precursor.
[0012] S4. The catalyst precursor is placed in a hydrogen atmosphere at 200℃~700℃ for calcination to obtain a dehydrogenation catalyst.
[0013] Preferably, in step S1, the first metal@molecular sieve includes a first metal and a molecular sieve, wherein the first metal includes one of Co, Mn, V, and Cu, and the molecular sieve includes one of S-1, MCM-41, and Beta molecular sieve.
[0014] Preferably, the preparation method of the first metal@molecular sieve includes the following steps:
[0015] S11. Dissolve the template agent in deionized water, then add the silicon source and the first metal precursor solution, and stir evenly at room temperature to obtain the first gel solution;
[0016] S12. The first gel solution is crystallized at 80-230℃ for 24-72h, then centrifuged and washed, dried at 50-120℃, and then calcined at 200-700℃ to obtain the first metal@molecular sieve.
[0017] Preferably, the silicon source in step S11 includes one or a combination of fumed silica, silica gel, sodium silicate, and tetraethoxysilane.
[0018] Preferably, in step S11, the first metal precursor solution is prepared from a nitrate or chloride salt of a first metal, wherein the first metal includes one of Co, Mn, V, and Cu.
[0019] Preferably, the template agent in step S11 includes one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, and hexadecyltrimethylammonium bromide.
[0020] Preferably, the Pt precursor aqueous solution in step S2 includes an aqueous solution of chloroplatinic acid or dinitrosodiaminoplatinum.
[0021] Preferably, the non-precious metal precursor in step S2 is a non-precious metal nitrate or chloride salt, wherein the non-precious metal includes one or a combination of Ni, Sn, Zn, Fe, and In.
[0022] Preferably, the mass ratio of Pt to non-precious metal in the aqueous solution of the metal precursor in step S2 is 1:1 to 1:4.
[0023] Preferably, the Pt loading in the dehydrogenation catalyst obtained in step S4 is 0.2 wt% to 1 wt%.
[0024] The present invention also provides a dehydrogenation catalyst prepared by the above-described method for preparing propane dehydrogenation catalyst.
[0025] In addition, the present invention also provides an application of a dehydrogenation catalyst, which is applied in the dehydrogenation reaction of propane oxidation to olefins by carbon dioxide, wherein the dehydrogenation catalyst is prepared by the above-described method for preparing propane dehydrogenation catalyst.
[0026] Preferably, the volume ratio of propane to carbon dioxide in the dehydrogenation reaction is 1:(1-7).
[0027] Preferably, the dehydrogenation reaction is carried out at a temperature of 400–600°C, and the propane space velocity is 1–20 h⁻¹. -1 .
[0028] As described above, the propane dehydrogenation catalyst, preparation method, and application of the present invention have the following beneficial effects:
[0029] This invention first encapsulates one active site within a molecular sieve framework using an in-situ encapsulation method, and then loads another active site, Pt metal, onto the surface of the molecular sieve using an impregnation method, thereby forming a propane dehydrogenation catalyst with two active sites. This dehydrogenation catalyst has a low noble metal loading and is used as a dehydrogenation catalyst in the catalytic oxidation of propane by carbon dioxide. Propane undergoes a dehydrogenation reaction to produce propylene and hydrogen, while carbon dioxide undergoes a reverse water-gas reaction to produce carbon monoxide and water. The two active sites of the dehydrogenation catalyst are responsible for activating propane and carbon dioxide, respectively, promoting the forward shift of the reaction equilibrium. This dehydrogenation catalyst exhibits excellent catalytic activity and propylene yield, while reducing the catalyst deactivation rate, providing a new solution for the greening and economicalization of propylene production. Attached Figure Description
[0030] Figure 1 The diagram shows the preparation process of the propane dehydrogenation catalyst of the present invention.
[0031] Figure 2The image shown is the XRD pattern of the propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.5% V@S-1) prepared in Example 13 of this invention.
[0032] Figure 3 The image shown is a SEM image of the propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.5% V@S-1) prepared in Example 13 of this invention. Detailed Implementation
[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0034] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.
[0035] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.
[0036] This invention provides a method for preparing a propane dehydrogenation catalyst, the method comprising the following steps:
[0037] S1. The first metal@molecular sieve was prepared by in-situ encapsulation method;
[0038] S2. Stir and mix the Pt precursor aqueous solution and the non-precious metal precursor aqueous solution to obtain a metal precursor aqueous solution;
[0039] S3. The first metal@molecular sieve is added to the aqueous solution of the metal precursor as a support. After stirring evenly at room temperature, it is vacuum dried at 50℃~120℃ (e.g., 50℃, 70℃, 90℃, 100℃, 110℃, 120℃, etc.) to obtain the catalyst precursor.
[0040] S4. The catalyst precursor is placed in a hydrogen atmosphere at 200℃~700℃ (e.g., 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, etc.) for calcination to obtain the dehydrogenation catalyst.
[0041] Specifically, in a specific embodiment of the present invention, an active site (first metal) is first encapsulated in the molecular sieve framework by an in-situ encapsulation method. Then, using the first metal@molecular sieve as a carrier, another active site, Pt metal, is loaded onto the surface of the molecular sieve by an impregnation method, thereby forming a propane dehydrogenation catalyst with two active sites.
[0042] As an example, in step S1, the first metal@molecular sieve includes a first metal and a molecular sieve. The first metal includes one of Co, Mn, V, and Cu, and the molecular sieve includes one of S-1, MCM-41, and Beta molecular sieve.
[0043] As an example, the preparation method of the first metal@molecular sieve in step S1 includes the following steps:
[0044] S11. Dissolve the template agent in deionized water, then add the silicon source and the first metal precursor solution, and stir evenly at room temperature to obtain the first gel solution;
[0045] S12. The first gel solution is crystallized at 80-230℃ for 24-72h, then centrifuged and washed, dried at 50-120℃, and then calcined at 200-700℃ to obtain the first metal@molecular sieve.
[0046] Specifically, the temperature for the first gel liquid crystallization can be any value within the range of 80℃, 100℃, 150℃, 200℃, 220℃, 230℃, etc., and the crystallization time can be any value within the range of 24h, 36h, 48h, 60h, 72h, etc.; deionized water or anhydrous ethanol is used for washing, and the drying temperature can be any value within the range of 50℃, 60℃, 80℃, 100℃, 120℃, etc.; after drying, calcination is performed, and the calcination temperature can be any value within the range of 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, etc.
[0047] As an example, the silicon source in step S11 includes one or a combination of fumed silica, silica gel, sodium silicate, and tetraethoxysilane.
[0048] As an example, the first metal precursor solution in step S11 is prepared from a nitrate or chloride salt of a first metal, wherein the first metal includes one of Co, Mn, V, and Cu.
[0049] Preferably, the Co precursor solution is a cobalt nitrate complex [Co(NH2CH2CH2NH2)](NO3)2, the Cu precursor solution is [Cu(NH2CH2CH2NH2)](NO3)2, the V precursor solution is a vanadate solution, and the Mn precursor solution is manganese nitrate.
[0050] As an example, the template agent in step S11 includes one of tetrapropylammonium hydroxide (TPAOH), tetraethylammonium hydroxide (TEAOH), and hexadecyltrimethylammonium bromide (CTAB).
[0051] As an example, the Pt precursor in step S2 includes an aqueous solution of chloroplatinic acid or dinitrosodiaminoplatinum.
[0052] As an example, in step S2, the non-precious metal precursor is a non-precious metal nitrate or chloride salt, wherein the non-precious metal includes one or a combination of Ni, Sn, Zn, Fe, and In, and the non-precious metal is equivalent to an additive in the catalyst system.
[0053] As an example, in step S2, the mass ratio of Pt to non-precious metal in the aqueous solution of the metal precursor is 1:1 to 1:4.
[0054] Specifically, in step S2, the mass ratio between Pt and non-precious metals in the aqueous solution of the metal precursor can be any value within a range such as 1:1, 1:2, 1:3, 1:4, etc.
[0055] As an example, the Pt loading in the dehydrogenation catalyst obtained in step S4 is 0.2 wt% to 1 wt%.
[0056] Specifically, the loading of Pt in the dehydrogenation catalyst obtained in step S4 may include any value within the range of 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt%, 1wt%, etc.; the dehydrogenation catalyst includes Pt metal, a first metal@molecular sieve, and a non-precious metal, wherein the first metal@molecular sieve serves as a support, and Pt is loaded on the support. In a specific embodiment of the present invention, the loading of Pt refers to the mass ratio between Pt and the first metal@molecular sieve.
[0057] The present invention also provides a propane dehydrogenation catalyst, which is prepared by the above-described method for preparing propane dehydrogenation catalyst.
[0058] In addition, the present invention also provides an application of a dehydrogenation catalyst, wherein the dehydrogenation catalyst prepared by the above-described method for preparing propane dehydrogenation catalyst is applied to the dehydrogenation reaction of propane to olefins by carbon dioxide oxidation.
[0059] Specifically, this dehydrogenation catalyst is a propane dehydrogenation catalyst with two active sites. In the carbon dioxide oxidation of propane dehydrogenation reaction, propane undergoes a dehydrogenation reaction to produce propylene and hydrogen, while carbon dioxide undergoes a reverse water gas reaction to produce carbon monoxide and water. The two active sites of the dehydrogenation catalyst are responsible for activating propane and carbon dioxide, respectively, promoting the forward shift of the reaction equilibrium. This dehydrogenation catalyst exhibits excellent catalytic activity and propylene yield, while reducing the catalyst deactivation rate.
[0060] As an example, the volume ratio of propane to carbon dioxide in the dehydrogenation reaction is 1:(1-7).
[0061] Specifically, the volume ratio between propane and carbon dioxide in the dehydrogenation reaction can be any value within a range such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc.
[0062] As an example, the dehydrogenation reaction temperature is 400–600 °C, and the propane space velocity is 1–20 h⁻¹. -1 .
[0063] Specifically, the reaction temperature for the dehydrogenation reaction can range from 400℃, 450℃, 500℃, 550℃, 600℃, etc., and the propane space velocity can be up to 1 h⁻¹. -1 3h -1 5h -1 10h -1 15h -1 20h -1 Values within any range.
[0064] To better understand the propane dehydrogenation catalyst, preparation method, and application of this invention, specific embodiments are described below. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.
[0065] Example 1
[0066] This embodiment provides a method for preparing a propane dehydrogenation catalyst, the method comprising the following steps:
[0067] S1. The first metal@molecular sieve (Cu@S-1) was prepared by in-situ encapsulation method;
[0068] S11. Dissolve 20g of tetrapropylammonium hydroxide (TPAOH) in 10g of water, then add 17g of tetraethoxysilane (TEOS), stir at room temperature for 2h, then add 5g of Cu metal with a mass concentration of 1wt% Cu precursor solution ([Cu(NH2CH2CH2NH2)](NO3)2) and continue stirring for 4h to obtain the first gel solution;
[0069] S12. The first gel solution is crystallized at 180℃ for 72h, then centrifuged and washed, dried at 80℃, and then calcined at 500℃ for 2h to obtain a first metal@molecular sieve with a first metal loading of 0.8wt% (denoted as: 0.8%Cu@S-1).
[0070] S2. Mix 1g of Pt in a 0.5wt% aqueous solution of chloroplatinic acid and 1g of Sn in a 0.5wt% aqueous solution of tin tetrachloride to obtain an aqueous solution of the metal precursor (wherein, the mass ratio of Pt to Sn is 1:1).
[0071] S3. Add 1g of the first metal@molecular sieve as a support to 2g of the metal precursor aqueous solution, stir at room temperature for 3h, and dry overnight in a vacuum drying oven at 80℃ to obtain the catalyst precursor.
[0072] S4. The catalyst precursor is placed in a tube furnace and calcined in a hydrogen atmosphere at 300°C to obtain the dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 0.8%Cu@S-1).
[0073] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.8% Cu@S-1), which is prepared in this embodiment. The loading of Pt in the propane dehydrogenation catalyst is 0.5 wt%, that is, the mass ratio of Pt to Cu@S-1 is 0.5 wt%.
[0074] Example 2
[0075] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S2, 1 g of chloroplatinic acid aqueous solution with a mass concentration of 0.5 wt% and 1 g of zinc nitrate aqueous solution with a mass concentration of 0.5 wt% are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein the mass ratio of Pt to Zn is 1:1). Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.5%Pt-0.5%Zn / 0.8%Cu@S-1).
[0076] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Zn / 0.8% Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0077] Example 3
[0078] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S2, 1 g of chloroplatinic acid aqueous solution with a mass concentration of 0.5 wt% and 1 g of ferric nitrate aqueous solution with a mass concentration of 0.5 wt% are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein the mass ratio of Pt to Fe is 1:1). Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.5%Pt-0.5%Fe / 0.8%Cu@S-1).
[0079] This embodiment also provides a propane dehydrogenation catalyst (0.5%Pt-0.5%Fe / 0.8%Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5wt%.
[0080] Example 4
[0081] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S2, 1 g of chloroplatinic acid aqueous solution with a mass concentration of 0.5 wt% and 1 g of indium nitrate aqueous solution with a mass concentration of 0.5 wt% are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein the mass ratio of Pt to In is 1:1). Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.5%Pt-0.5%In / 0.8%Cu@S-1).
[0082] This embodiment also provides a propane dehydrogenation catalyst (0.5%Pt-0.5%In / 0.8%Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5wt%.
[0083] Example 5
[0084] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is as follows: In step S2, 1g of chloroplatinic acid aqueous solution with a mass concentration of 0.5wt% for Pt and 2g of tin tetrachloride aqueous solution with a mass concentration of 0.5wt% for Sn are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein, the mass ratio of Pt to Sn is 1:2); In step S3, 1g of the first metal@molecular sieve is added as a support to 3g of the aqueous solution of the metal precursor, stirred at room temperature for 3h, and dried overnight in a vacuum drying oven at 80℃ to obtain the catalyst precursor; Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.5%Pt-1%Sn / 0.8%Cu@S-1).
[0085] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-1% Sn / 0.8% Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0086] Example 6
[0087] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is as follows: In step S2, 1g of chloroplatinic acid aqueous solution with a mass concentration of 0.5wt% for Pt and 3g of tin tetrachloride aqueous solution with a mass concentration of 0.5wt% for Sn are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein, the mass ratio of Pt to Sn is 1:3); In step S3, 1g of the first metal@molecular sieve is added as a support to 4g of the aqueous solution of the metal precursor, stirred at room temperature for 3h, and dried overnight in a vacuum drying oven at 80℃ to obtain the catalyst precursor; Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.5%Pt-1.5%Sn / 0.8%Cu@S-1).
[0088] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-1.5% Sn / 0.8% Cu@S-1), which was prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0089] Example 7
[0090] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S2, 1 g of chloroplatinic acid aqueous solution with a mass concentration of 0.2 wt% and 1 g of tin tetrachloride aqueous solution with a mass concentration of 0.2 wt% are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein the mass ratio of Pt to Sn is 1:1). Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.2%Pt-0.2%Sn / 0.8%Cu@S-1).
[0091] This embodiment also provides a propane dehydrogenation catalyst (0.2% Pt-0.2% Sn / 0.8% Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.2 wt%.
[0092] Example 8
[0093] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S2, 1 g of Pt in a 0.2 wt% aqueous solution of chloroplatinic acid and 1 g of Sn in a 0.5 wt% aqueous solution of tin tetrachloride are stirred and mixed to obtain an aqueous solution of the metal precursor (wherein the mass ratio of Pt to Sn is 1:2.5). Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.2%Pt-0.5%Sn / 0.8%Cu@S-1).
[0094] This embodiment also provides a propane dehydrogenation catalyst (0.2% Pt-0.5% Sn / 0.8% Cu@S-1), which was prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.2 wt%.
[0095] Example 9
[0096] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is as follows: In step S2, 1g of chloroplatinic acid aqueous solution with a mass concentration of 0.2wt% for Pt and 4g of tin tetrachloride aqueous solution with a mass concentration of 0.2wt% for Sn are stirred and mixed to obtain an aqueous solution of metal precursor (wherein, the mass ratio of Pt to Sn is 1:4); In step S3, 1g of the first metal@molecular sieve is added as a support to the above 5g aqueous solution of metal precursor, stirred at room temperature for 3h, and dried overnight in a vacuum drying oven at 80℃ to obtain the catalyst precursor; Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, the dehydrogenation catalyst is obtained (denoted as: 0.2%Pt-0.8%Sn / 0.8%Cu@S-1).
[0097] This embodiment also provides a propane dehydrogenation catalyst (0.2% Pt-0.8% Sn / 0.8% Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.2 wt%.
[0098] Example 10
[0099] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is as follows: In step S2, 1g of chloroplatinic acid aqueous solution with a mass concentration of 1wt% for Pt and 1g of tin tetrachloride aqueous solution with a mass concentration of 1wt% for Sn are stirred and mixed to obtain a metal precursor aqueous solution (wherein, the mass ratio of Pt to Sn is 1:1); In step S3, 1g of a first metal@molecular sieve is added as a support to the above 2g metal precursor aqueous solution, stirred at room temperature for 3h, and dried overnight in a vacuum drying oven at 80℃ to obtain the catalyst precursor; Other methods and steps are the same as in Example 1 and will not be repeated here. Finally, a dehydrogenation catalyst is obtained (denoted as: 1%Pt-1%Sn / 0.8%Cu@S-1).
[0100] This embodiment also provides a propane dehydrogenation catalyst (1%Pt-1%Sn / 0.8%Cu@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 1wt%.
[0101] Example 11
[0102] This embodiment provides a method for preparing a propane dehydrogenation catalyst, which differs from that in Example 1 in that: in step S1, the first metal@molecular sieve (Co@S-1) is prepared using an in-situ encapsulation method; in step S11, 20g of tetrapropylammonium hydroxide (TPAOH) is dissolved in 10g of water, then 17g of tetraethoxysilane (TEOS) is added, and after stirring at room temperature for 2h, 5g of [unspecified substance] is added. A Co precursor solution with a Co metal mass concentration of 2 wt% ([Co(NH2CH2CH2NH2)](NO3)2) was stirred for 4 h to obtain a first gel solution; S12 involves crystallizing the first gel solution at 180 °C for 72 h, then centrifuging and washing it, drying it at 80 °C, and calcining it at 500 °C for 2 h to obtain a first metal@molecular sieve with a first metal loading of 1.5 wt% (denoted as: 1.5%Co@S-1); other methods and steps are different from those in Example 1 and will not be repeated here to obtain a dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 1.5%Co@S-1).
[0103] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 1.5% Co@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0104] Example 12
[0105] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Embodiment 1 is that: in step S1, an in-situ encapsulation method is used to prepare the first metal@molecular sieve (Mn@S-1); in step S11, 20g of tetrapropylammonium hydroxide (TPAOH) is dissolved in 10g of water, and then 17g of tetraethoxysilane (TEOS) is added. After stirring at room temperature for 2h, 5g of a 3% Mn precursor solution (Mn(NO3)2) is added and stirring continues. After 4 hours, the first gel solution was obtained; S12 involves crystallizing the first gel solution at 180°C for 72 hours, then centrifuging and washing it, drying it at 80°C, and then calcining it at 500°C for 2 hours to obtain a first metal@molecular sieve with a first metal loading of 2.5 wt% (denoted as: 2.5%Mn@S-1); other methods and steps are different from those in Example 1 and will not be repeated here, to obtain a dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 2.5%Mn@S-1).
[0106] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 2.5% Mn@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0107] Example 13
[0108] This embodiment provides a method for preparing a propane dehydrogenation catalyst, which differs from that in Example 1 in that: in step S1, the first metal@molecular sieve (V@S-1) is prepared using an in-situ encapsulation method; in step S11, 20g of tetrapropylammonium hydroxide (TPAOH) is dissolved in 10g of water, then 17g of tetraethoxysilane (TEOS) is added, and after stirring at room temperature for 2h, 5g of a V precursor solution with a mass concentration of 0.8% (NaVO3) is added and stirring continues for 4 hours. h, to obtain the first gel solution; S12 is to crystallize the first gel solution at 180°C for 72 h, then centrifuge and wash it, dry it at 80°C, and then calcine it at 500°C for 2 h to obtain the first metal@molecular sieve with a first metal loading of 0.5 wt% (denoted as: 0.5%V@S-1); other methods and steps are different from those in Example 1, and will not be repeated here, to obtain the dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 0.5%V@S-1).
[0109] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.5% V@S-1), which is prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0110] See Figure 2The image shows the XRD pattern of the propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.5% V@S-1) prepared in this embodiment. As can be seen from the image, the diffraction peaks of the dehydrogenation catalyst correspond completely to those of pure S-1 molecular sieve, and there are no characteristic diffraction peaks of the metal. This is because the amount of metal used in the preparation process is very small, making it difficult to form large-particle crystals. In addition, the molecular sieve has a large specific surface area, and the loaded metal is highly dispersed on the surface of the molecular sieve.
[0111] See Figure 3 The image shows the SEM spectrum of the propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 0.5% V@S-1) prepared in this embodiment. As can be seen from the image, the dehydrogenation catalyst presents a uniform hexagonal block with a size of about 150 nm, which is almost identical to the microstructure of pure S-1 molecular sieve, indicating that the introduction of metal did not affect the microstructure of the material.
[0112] Example 14
[0113] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S1, an in-situ encapsulation method is used to prepare the first metal@molecular sieve (Cu@Beta), specifically:
[0114] S11, 10g NaOH and 15g TEAOH solution were dissolved in 7g deionized water. 3g Cu precursor solution with a mass concentration of 1wt% ([Cu(NH2CH2CH2NH2)](NO3)2) was added to the above solution. After stirring for 20 minutes, 1g pure silicon BEA crystal seed was added and stirred evenly. Then 14g fumed silica was added to obtain the first gel solution.
[0115] S12. After aging the first gel solution overnight, it is dried at 100°C for 24 hours to obtain a dry gel. The dry gel and 0.5 g of deionized water are sealed in a stainless steel autoclave with a Teflon liner and crystallized at 150°C for 72 hours. After washing and drying, it is calcined in air at 550°C for 6 hours to obtain a first metal@molecular sieve with a first metal loading of 1 wt% (denoted as: 1% Cu@Beta).
[0116] Other methods and steps differ from those in Example 1 and will not be repeated here, resulting in a dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 1%Cu@Beta).
[0117] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / 1% Cu@Beta), which was prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0118] Example 15
[0119] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Example 1 is that in step S1, an in-situ encapsulation method is used to prepare the first metal@molecular sieve (Cu@MCN-41), specifically:
[0120] S11. Dissolve 20g of CTAB in water, stir gently with a magnetic force until the solution is clear, then add 5g of Cu precursor solution with a mass concentration of 1wt% ([Cu(NH2CH2CH2NH2)](NO3)2) and continue stirring for 1h. This solution is called solution A. Dissolve 17g of sodium silicate in 20g of distilled water and slowly add it to solution A. Continue stirring for about 1h to obtain the first gel solution.
[0121] S12. Adjust the pH of the first gel solution to about 10 with hydrochloric acid solution. At this point, it becomes a white gel. Then, pour it into a stainless steel reactor and crystallize it at 100°C for 36 hours. After cooling to room temperature, filter it with a Buchner funnel, wash away the surfactant foam with distilled water, dry it for 12 hours, and then calcine it in a muffle furnace at 500°C for 6 hours to obtain a first metal@molecular sieve with a first metal loading of 0.5 wt% (denoted as: 0.5% Cu@MCM-41).
[0122] Other methods and steps differ from those in Example 1 and will not be repeated here, resulting in a dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 0.5%Cu@MCN-41).
[0123] This embodiment also provides a propane dehydrogenation catalyst (0.5% Pt-0.5% Sn / Cu@MCN-41), which was prepared in this embodiment, and the Pt loading in the propane dehydrogenation catalyst is 0.5 wt%.
[0124] Example 16
[0125] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Embodiment 1 is that in step S4, the catalyst precursor is placed in a tube furnace and calcined in a hydrogen atmosphere at 500°C to obtain the dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 0.8%Cu@S-1).
[0126] Example 17
[0127] This embodiment provides a method for preparing a propane dehydrogenation catalyst. The difference between this method and that of Embodiment 1 is that in step S4, the catalyst precursor is placed in a tube furnace and calcined in a hydrogen atmosphere at 700°C to obtain the dehydrogenation catalyst (denoted as: 0.5%Pt-0.5%Sn / 0.8%Cu@S-1).
[0128] Application Example 1
[0129] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Examples 1-17 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 3 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:1:5. After the gas mixture was passed through the dehydrogenation catalyst bed, the products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 1.
[0130] Table 1 shows the propane conversion and propylene selectivity of the propane dehydrogenation catalysts prepared in Examples 1-17 when applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide.
[0131]
[0132]
[0133] Application Example 2
[0134] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 20 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:1:5. After the gas was mixed, it passed through the dehydrogenation catalyst bed. The products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0135] Application Example 3
[0136] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 10 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:1:5. After the gas was mixed, it passed through the dehydrogenation catalyst bed. The products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0137] Application Example 4
[0138] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 1 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:1:5. After the gas was mixed, it passed through the dehydrogenation catalyst bed. The products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0139] Application Example 5
[0140] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 3 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:2:5. After the gas was mixed, it passed through the dehydrogenation catalyst bed. The products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0141] Application Example 6
[0142] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 3 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:3:5. After the gas mixture was passed through the dehydrogenation catalyst bed, the products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0143] Application Example 7
[0144] This application example provides an application of a dehydrogenation catalyst. The propane dehydrogenation catalyst prepared in Example 1 is applied to the dehydrogenation reaction of propane oxidation to olefins using carbon dioxide. Specifically, the dehydrogenation catalyst is loaded into the middle of a quartz tube with an inner diameter of 6 mm, with a loading amount of 0.15 g. The temperature of the fixed bed is 550 °C, and the propane space velocity is 3 h⁻¹. -1 The dehydrogenation reaction was carried out in an N2 atmosphere. The volume ratio of the reaction gas composition C3H8, CO2, and N2 was 1:7:5. After the gas mixture was passed through the dehydrogenation catalyst bed, the products of the fixed-bed reactor were analyzed by online gas chromatography (GC) to obtain the propane conversion rate and propylene selectivity. The specific results are shown in Table 2.
[0145] Table 2 shows the propane conversion and propylene selectivity results when the propane dehydrogenation catalyst prepared in Example 1 was applied to the dehydrogenation reaction of propane to olefins by carbon dioxide oxidation in Examples 2-7.
[0146] project Propane conversion rate / % Propylene selectivity / wt% Application Example 2 45.64 98.67 Application Example 3 50.87 96.38 Application Example 4 62.89 92.68 Application Example 5 57.3 95.42 Application Example 6 54.93 92.86 Application Example 7 46.96 91.35
[0147] In summary, this invention first encapsulates one active site within a molecular sieve framework using an in-situ encapsulation method, and then loads another active site, Pt metal, onto the surface of the molecular sieve using an impregnation method, thereby forming a propane dehydrogenation catalyst with two active sites. This dehydrogenation catalyst has a low noble metal loading and is used as a dehydrogenation catalyst in the catalytic oxidation of propane by carbon dioxide. Propane undergoes dehydrogenation to produce propylene and hydrogen, while carbon dioxide undergoes a reverse water-gas reaction to produce carbon monoxide and water. The two active sites of the dehydrogenation catalyst are responsible for activating propane and carbon dioxide, respectively, promoting the forward shift of the reaction equilibrium. This dehydrogenation catalyst exhibits excellent catalytic activity and propylene yield, while simultaneously reducing the catalyst deactivation rate, providing a new solution for the greening and economicalization of propylene production. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.
[0148] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for preparing a propane dehydrogenation catalyst, characterized in that, The preparation method includes the following steps: S1. The first metal@molecular sieve was prepared by in-situ encapsulation method; S2. Stir and mix the Pt precursor aqueous solution and the non-precious metal precursor aqueous solution to obtain a metal precursor aqueous solution; S3. The first metal@molecular sieve is added to the aqueous solution of the metal precursor as a support, stirred evenly at room temperature, and then vacuum dried at 50℃~120℃ to obtain the catalyst precursor. S4. The catalyst precursor is placed in a hydrogen atmosphere at 200℃~700℃ for calcination to obtain a dehydrogenation catalyst.
2. The method for preparing the propane dehydrogenation catalyst according to claim 1, characterized in that: In step S1, the first metal@molecular sieve includes a first metal and a molecular sieve. The first metal includes one of Co, Mn, V, and Cu, and the molecular sieve includes one of S-1, MCM-41, and Beta molecular sieve.
3. The method for preparing the propane dehydrogenation catalyst according to claim 2, characterized in that: The preparation method of the first metal@molecular sieve includes the following steps: S11. Dissolve the template agent in deionized water, then add the silicon source and the first metal precursor solution, and stir evenly at room temperature to obtain the first gel solution; S12. The first gel solution is crystallized at 80-230℃ for 24-72h, then centrifuged and washed, dried at 50-120℃, and then calcined at 200-700℃ to obtain the first metal@molecular sieve.
4. The method for preparing the propane dehydrogenation catalyst according to claim 3, characterized in that: Step S11 includes one or a combination of the following conditions: The silicon source includes one or a combination of fumed silica, silica gel, sodium silicate, and tetraethoxysilane. The first metal precursor solution is prepared from a nitrate or chloride salt of a first metal, wherein the first metal includes one of Co, Mn, V, and Cu. The template agent includes one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, and hexadecyltrimethylammonium bromide.
5. The method for preparing the propane dehydrogenation catalyst according to claim 1, characterized in that: Step S2 includes one or a combination of the following conditions: The Pt precursor aqueous solution includes an aqueous solution of chloroplatinic acid or dinitrosodiaminoplatinum; The non-precious metal precursor is a nitrate or chloride salt of a non-precious metal, wherein the non-precious metal includes one or a combination of Ni, Sn, Zn, Fe, and In. The mass ratio of Pt to non-precious metal in the aqueous solution of the metal precursor is 1:1 to 1:
5.
6. The method for preparing the propane dehydrogenation catalyst according to claim 1, characterized in that: The Pt loading in the dehydrogenation catalyst obtained in step S4 is 0.2 wt% to 1 wt%.
7. A dehydrogenation catalyst prepared by the method for preparing a propane dehydrogenation catalyst according to any one of claims 1 to 6.
8. The application of a dehydrogenation catalyst, characterized in that: The dehydrogenation catalyst is applied in the dehydrogenation reaction of propane to olefins by carbon dioxide oxidation, wherein the dehydrogenation catalyst is prepared by the preparation method of propane dehydrogenation catalyst according to any one of claims 1 to 6.
9. The application of the dehydrogenation catalyst according to claim 8, characterized in that: In the dehydrogenation reaction, the volume ratio of propane to carbon dioxide is 1:(1-7).
10. The application of the dehydrogenation catalyst according to claim 8, characterized in that: The dehydrogenation reaction is carried out at a temperature of 400–600 °C, and the propane space velocity is 1–20 h⁻¹. -1 .