Propane dehydrogenation catalyst suitable for in-situ Joule heating and preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly discloses a propane dehydrogenation catalyst suitable for in-situ Joule heating and a preparation method and application thereof.The catalyst comprises a conductive foam substrate and a catalytic layer coated on the substrate, the catalytic layer comprises a composite metal oxide carrier Mg (M) (Al) O and an active center intermetallic compound PtM dispersed on the carrier, m in the carrier and the active center is Zn, In, Ga or Y. The preparation method comprises the following steps: 1) preparing a hydrotalcite precursor MgAlM-LDHs, and impregnating and loading a Pt precursor solution on the hydrotalcite precursor to obtain a precursor of a catalyst layer; the preparation method comprises 1) preparing a catalyst layer, 2) coating a substrate with the precursor slurry of the catalyst layer to obtain a precursor of the catalyst, and 3) carrying out roasting and reduction treatment on the precursor of the catalyst to obtain the catalyst.The catalyst keeps high propylene selectivity and activity in a Joule heating propane dehydrogenation reaction, and the propylene yield can be improved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a propane dehydrogenation catalyst suitable for in-situ Joule heating and its preparation method, and the application of the catalyst in propane dehydrogenation to propylene. Background Technology

[0002] Strongly endothermic reactions are widespread in many important chemical processes. In strongly endothermic reactions such as dehydrogenation of low-carbon alkanes and dry reforming of methane, continuous and timely energy supply is required to maintain high-temperature reaction conditions, thereby achieving economically feasible conversion rates. Therefore, energy supply efficiency plays a crucial role in ensuring reaction efficiency. Traditional heating typically utilizes the heat generated by the combustion of fossil fuels to heat the reactor. Heat is gradually transferred to the inner catalyst bed through radiation and conduction, first heating the outer wall of the reactor. This method has inherent drawbacks such as heat transfer lag, large temperature gradients, and low energy utilization, severely restricting the efficient execution of strongly endothermic reactions. Therefore, how to timely supply energy to the active sites of strongly endothermic reactions to overcome the heat transfer bottleneck and improve reaction efficiency has become a key challenge that urgently needs to be addressed in the chemical industry.

[0003] In recent years, novel heating systems such as in-situ resistance heating, microwave heating, electromagnetic induction heating, and photothermal synergy have been widely reported, providing new ideas for powering strongly endothermic reactions. Among them, in-situ resistance heating technology can directly supply energy to the catalyst, and its advantages such as precise heating, low energy consumption, and fast temperature response have attracted widespread attention. Furthermore, during in-situ resistance heating, the current flowing through the catalyst simultaneously introduces an electric field effect, which affects the catalytic reaction performance and its mechanism of action. Currently, researchers have conducted extensive research on the performance enhancement mechanism of strongly endothermic reactions through in-situ resistance heating, revealing that reaction performance can be enhanced by increasing the heating rate, altering the adsorption / desorption intensity of reactants / products, promoting the hopping of surface protons, and regulating surface oxygen species. However, how to construct a suitable in-situ resistance heating system remains a core research challenge in this field. Summary of the Invention

[0004] In response to the above situation, the inventors of this invention have discovered that adjusting the resistance, pore structure, and metal-support interaction of the substrate material can be the main direction for regulating the thermal and electric fields and improving the catalytic activity of the catalyst. Based on this, the purpose of this invention is to provide a propane dehydrogenation catalyst suitable for in-situ Joule heating, its preparation method, and its application. This catalyst exhibits high activity and excellent propylene selectivity in the propane dehydrogenation reaction catalyzed by in-situ Joule heating, and the catalytic system achieves high propylene yield with low energy consumption.

[0005] A first aspect of the present invention provides a propane dehydrogenation catalyst suitable for in-situ Joule heating, the catalyst comprising a conductive foam substrate and a catalyst layer coated on the substrate, the catalyst layer comprising a composite metal oxide support Mg(M)(Al)O and an active center intermetallic compound PtM dispersed on the support, wherein M in the support and the active center is Zn, In, Ga or Y.

[0006] A second aspect of the present invention provides a method for preparing the above-described propane dehydrogenation catalyst suitable for in-situ Joule heating, the method comprising the following steps: 1) Prepare hydrotalcite precursor MgAlM-LDHs by impregnating the hydrotalcite precursor with Pt precursor solution to obtain the precursor of the catalyst layer; 2) The precursor slurry of the catalyst layer is coated onto the substrate to obtain the catalyst precursor; 3) The precursor of the catalyst is calcined and reduced to obtain the catalyst.

[0007] The third aspect of the present invention provides the application of the above-described propane dehydrogenation catalyst suitable for in-situ Joule heating in the production of propylene from propane dehydrogenation, wherein the energy supply for propane dehydrogenation is in-situ Joule heating.

[0008] Compared with the prior art, the present invention has the following beneficial effects: In the catalyst of this invention, the foam substrate possesses both semiconductor and conductor properties, enabling rapid heating with the application of a weak current, thus providing a highly efficient thermal response guarantee for the propane dehydrogenation reaction. Simultaneously, the foam substrate exhibits a macroporous structure, providing abundant attachment sites for the precursor of the catalyst layer, thereby promoting the formation of a tightly bonded interface structure between the foam substrate and the catalyst layer. This structural design allows for the creation of a localized high-temperature environment in the catalytic microregion, significantly enhancing the dehydrogenation activity of the catalyst. Furthermore, when current flows through the catalyst, in addition to constructing the thermal field required for the reaction, an electric field is simultaneously introduced, further enhancing the dehydrogenation activity through a thermo-electric synergistic effect. It is noteworthy that M in the composite metal oxide support... Existing in a monodisperse form, this morphology can effectively anchor the intermetallic compound PtM, significantly suppressing the aggregation of active sites, thereby greatly improving the structural stability of the catalyst.

[0009] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0010] Figure 1 The image shows the XRD pattern of the catalyst prepared in Example 1 of this invention. Detailed Implementation

[0011] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0012] According to a first aspect of the present invention, the present invention provides a propane dehydrogenation catalyst suitable for in-situ Joule heating, the catalyst comprising a conductive foam substrate and a catalyst layer coated on the substrate, said catalyst layer comprising a composite metal oxide support Mg(M)(Al)O and an active center intermetallic compound PtM dispersed on the support, wherein M in the support and the active center is Zn, In, Ga or Y.

[0013] In this invention, the substrate can be foamed silicon carbide, foamed carbon, foamed copper, or foamed aluminum. The porosity of the substrate can be 30-120 ppi, preferably 50-120 ppi, and more preferably 90 ppi. The shape of the foam substrate can be selected as needed, for example, it can be a cylinder with a diameter of 6-12 mm and a length of 10-50 mm, preferably a cylinder with a diameter of 8 mm and a length of 20 mm.

[0014] According to the present invention, the content of Pt can be 0.1-0.5 wt%, preferably 0.3 wt%, based on the total weight of the catalyst, and the content of M can be 0.1-10 wt%, preferably 3-8 wt%, more preferably 4 wt%.

[0015] In this invention, the particle size of the intermetallic compound PtM can be 0.5-3 nm.

[0016] According to a second aspect of the present invention, the present invention provides a method for preparing the above-described propane dehydrogenation catalyst suitable for in-situ Joule heating, the method comprising the following steps: 1) Prepare hydrotalcite precursor MgAlM-LDHs by impregnating the hydrotalcite precursor with Pt precursor solution to obtain the precursor of the catalyst layer; 2) The precursor slurry of the catalyst layer is coated onto the substrate to obtain the catalyst precursor; 3) The precursor of the catalyst is calcined and reduced to obtain the catalyst.

[0017] This invention employs a preparation process of "first loading Pt onto hydrotalcite, and then coating the Pt-loaded hydrotalcite onto a foam substrate." By utilizing the inherent high specific surface area of ​​hydrotalcite and the monodisperse additive M, efficient dispersion of the PtM active component can be achieved, thereby forming a uniformly structured catalyst precursor. After the precursor is loaded onto the foam substrate through coating, it can form a stable bond with the substrate, significantly improving the catalyst's loading stability and structural integrity.

[0018] In step 1) of this invention, the Pt precursor solution can be loaded using the initial wet impregnation method, with the mixture being shaken evenly during the impregnation process, and then dried at 100-130℃ for 1-5 hours to obtain the precursor of the catalyst layer.

[0019] According to the present invention, in step 2), the coating is carried out by spin coating. While the substrate is rotating, the precursor slurry of the catalyst layer is dropped onto the substrate surface to form a thin film layer, and then dried to obtain the catalyst precursor.

[0020] Specifically, the spin coating method includes: first, fixing the foam substrate on the vacuum adsorption rotating stage of a spin coater, ensuring the substrate is centered and stable; then, adding a Pt-loaded hydrotalcite precursor solution dropwise onto the surface of the foam substrate; starting the equipment to make the substrate rotate at high speed with the rotating stage, using centrifugal force to rapidly spread and uniformly adhere the precursor solution on the substrate surface, while excess solution is thrown off under centrifugal force, ultimately forming a uniform thin film layer on the substrate surface. The spin coating time is generally 20-40 minutes, followed by drying at a temperature of 100-130℃ for 1-3 hours.

[0021] In this invention, the calcination conditions include: calcination at 600-800℃ for 2-4 hours in a N2 atmosphere, with a heating rate of 1-10℃ / min, preferably 5℃ / min, and an N2 flow rate of 10-60mL / min, preferably 40mL / min.

[0022] According to the present invention, the conditions for reduction treatment include: reduction at 600-800°C for 2-4 h in an H2 atmosphere, with an H2 flow rate of 10-60 mL / min, preferably 40 mL / min.

[0023] According to a third aspect of the present invention, the present invention provides the application of the above-described propane dehydrogenation catalyst suitable for in-situ Joule heating in the production of propylene from propane dehydrogenation, wherein the energy supply for propane dehydrogenation is in-situ Joule heating.

[0024] The in-situ Joule heating in this invention can be achieved using conventional methods in the prior art. For example, a specific voltage is applied to the conductive catalyst by a DC power supply. When current flows through the catalyst, its own resistance converts electrical energy into heat energy, thereby achieving rapid in-situ heating.

[0025] In this invention, the conditions for propane dehydrogenation can be conventionally selected according to existing technology. Preferably, the reaction temperature for propane dehydrogenation is 300-550℃, and the reaction pressure is atmospheric pressure.

[0026] According to the present invention, the reaction feed can be C3H8, Ar and H2, with a molar ratio of C3H8∶H2∶Ar = 2∶1∶4; the propane mass hourly space velocity is 2-50 h⁻¹. -1 The catalyst dosage is 0.01-0.3g.

[0027] The substances and parameters not limited in this invention can be selected according to existing technology, which is a conventional technical means in this field.

[0028] The present invention will be further described below with reference to embodiments. However, the invention is not limited to these embodiments.

[0029] The raw materials and data for each embodiment and comparative example can be obtained by the following methods: SiC-Foam-90ppi: Purchased from Jilin Newstar Metal Materials Co., Ltd.

[0030] SiC-Foam-50ppi: Purchased from Jilin Newstar Metal Materials Co., Ltd.

[0031] SiC-Foam-110ppi: Purchased from Jilin Newstar Metal Materials Co., Ltd.

[0032] C-Foam-90ppi: Purchased from Kunshan Ansu Electronic Materials Business Department.

[0033] Cu-Foam-90ppi: Purchased from Kunshan Guangjiayuan Electronic Materials Business Department.

[0034] Al-Foam-90ppi: Purchased from Fuershun Electronic Materials.

[0035] Elemental content: Detected using inductively coupled plasma atomic emission spectrometry (ICP) with conventional methods.

[0036] The particle size of the intermetallic compounds was obtained by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).

[0037] Example 1

[0038] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0039] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0040] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / SiC-Foam-90ppi.

[0041] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / SiC-Foam-90ppi catalyst was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm. The XRD pattern of this catalyst is shown below. Figure 1 As shown, a distinct intermetallic compound phase structure can be observed.

[0042] Example 2

[0043] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: Synthesize the hydrotalcite precursor MgAlIn-LDHs using a coprecipitation method. First, weigh 0.45 mmol of Mg(N) ·6 O, 0.11 mmol Al(N) )3.9 A mixed salt solution was prepared by weighing 0.04 mmol of In(NO3)3·4H2O. Next, a mixed alkali solution was prepared by weighing 0.11 mmol of NaOH and 0.03 mmol of Na2CO3. The mixed salt and alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgAlIn-LDHs.

[0044] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgAlIn-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt 2+ / MgAlIn-LDHs.

[0045] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgAlIn-LDHs / SiC-Foam-90ppi.

[0046] Step D: The Pt prepared in step (C) 2+The / MgAlIn-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, it was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtIn / Mg(Al)(In)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual In content was 7.0 wt%, and the particle size of the PtIn intermetallic compound was 1.8 nm.

[0047] Example 3

[0048] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgAlGa-LDHs was synthesized using a coprecipitation method. First, 0.45 mmol of Mg(N) was weighed. ·6 O, 0.11 mmol Al(N) )3.9 A mixed salt solution was prepared by weighing 0.04 mmol of Ga(NO3)3·9H2O. Next, a mixed alkali solution was prepared by weighing 0.11 mmol of NaOH and 0.03 mmol of Na2CO3. The mixed salt and alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgAlGa-LDHs.

[0049] Step B: An equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) was impregnated into a round-bottom flask containing the MgAlGa-LDHs prepared in step (A), shaken thoroughly for 30 min, and then dried at 120℃ for 2 h to obtain Pt. 2+ / MgAlGa-LDHs.

[0050] Step C: The Pt prepared in step (B) 2+0.1 mL of silica sol was added to MgAlGa-LDHs to prepare a hydrotalcite precursor solution. Then, a SiC-Foam-90ppi substrate was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgAlGa-LDHs / SiC-Foam-90ppi.

[0051] Step D: The Pt prepared in step (C) 2+ The / MgAlGa-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtGa / Mg(Al)(Ga)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Ga content was 4.0 wt%, and the particle size of the PtGa intermetallic compound was 1.8 nm.

[0052] Example 4

[0053] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgAlY-LDHs was synthesized using a coprecipitation method. First, 0.45 mmol of Mg(N) was weighed. ·6 O, 0.11 mmol Al(N) )3.9 A mixed salt solution was prepared by weighing 0.04 mmol of Y(NO3)3·6H2O. Next, a mixed alkali solution was prepared by weighing 0.11 mmol of NaOH and 0.03 mmol of Na2CO3. The mixed salt and alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgAlY-LDHs.

[0054] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgAlY-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt 2+ / MgAlY-LDHs.

[0055] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgAlY-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgAlY-LDHs / SiC-Foam-90ppi.

[0056] Step D: The Pt prepared in step (C) 2+ The / MgAlY-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtY / Mg(Al)(Y)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Y content was 5.5 wt%, and the particle size of the PtY intermetallic compound was 1.8 nm.

[0057] Example 5

[0058] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0059] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt 2+ / MgZnAl-LDHs.

[0060] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-50ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / SiC-Foam-50ppi.

[0061] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / SiC-Foam-50ppi compound was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / SiC-Foam-50ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0062] Example 6

[0063] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0064] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0065] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-110ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / SiC-Foam-110ppi.

[0066] Step D: The Pt prepared in step (C) 2+The / MgZnAl-LDHs / SiC-Foam-110ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / SiC-Foam-110ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0067] Example 7

[0068] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0069] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0070] Step C: The Pt prepared in step (B) 2+0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, C-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the C-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the C-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the C-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / C-Foam-90ppi.

[0071] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / C-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / C-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0072] Example 8

[0073] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0074] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0075] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, Cu-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the Cu-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the Cu-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the Cu-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / Cu-Foam-90ppi.

[0076] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / Cu-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / Cu-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0077] Example 9

[0078] A method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating includes: Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0079] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0080] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, Al-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the Al-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the Al-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the Al-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / Al-Foam-90ppi.

[0081] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / Al-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, the furnace was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Zn)(Al)O / Al-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 4.0 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0082] Comparative Example 1

[0083] Step A: The hydrotalcite precursor MgZnAl-LDHs was synthesized using a coprecipitation method. First, 0.41 mmol of Mg(N) was weighed... ·6 O, 0.15 mmol Al(N) )3.9 O, 0.04 mmol Zn(N) ·6 A mixed salt solution was prepared. Next, 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ were weighed to prepare a mixed alkali solution. The mixed salt and mixed alkali solutions were simultaneously and slowly added dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 9.5. The crystallization temperature was 65℃, and the crystallization time was 12 h. The solid-liquid mixture was then filtered and washed with deionized water until neutral. The solid was then dried overnight in an oven at 120℃ to obtain MgZnAl-LDHs.

[0084] Step B: Immerse an equal volume of Pt(NH3)4(NO3)2 solution (concentration 0.08 mol / L) in a round-bottom flask containing the MgZnAl-LDHs prepared in step (A), shake thoroughly for 30 min, and dry at 120℃ for 2 h to obtain Pt. 2+ / MgZnAl-LDHs.

[0085] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgZnAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgZnAl-LDHs / SiC-Foam-90ppi.

[0086] Step D: The Pt prepared in step (C) 2+ The / MgZnAl-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 450℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, it was directly switched to H2 at a flow rate of 40 mL / min and reduced at 450℃ for 2 h to obtain Pt / Mg(Zn)(Al)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 3.5 wt%, and the Pt cluster particle size was 1.8 nm.

[0087] Comparative Example 2

[0088] Step A: Synthesize the hydrotalcite precursor MgAl-LDHs using a coprecipitation method. First, weigh 0.45 mmol of Mg(N) ·6 O, 0.15 mmol Al(N) )3.9 First, prepare a mixed salt solution. Next, weigh 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ to prepare a mixed alkali solution. Slowly add the mixed salt and mixed alkali solutions simultaneously dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 10. The crystallization temperature is 65℃, and the crystallization time is 12 h. Afterward, filter the solid-liquid mixture and wash with deionized water until neutral. Then, dry the solid in an oven at 120℃ overnight to obtain MgAl-LDHs.

[0089] Step B: Impregnate a round-bottom flask containing the MgAl-LDHs prepared in step (A) with an equal volume of Pt(NH3)4(NO3)2 (concentration of 0.08 mol / L) and Zn(N2)2. ·6 A mixed solution of O (concentration 0.35 mol / L) was shaken thoroughly for 30 min and then dried at 120℃ for 2 h to obtain Pt. 2+ Zn 2+ / MgAl-LDHs.

[0090] Step C: The Pt prepared in step (B) 2+ Zn 2+ 0.1 mL of silica sol was added to MgAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ Zn 2+ / MgAl-LDHs / SiC-Foam-90ppi.

[0091] Step D: The Pt prepared in step (C) 2+ Zn 2+The / MgAl-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, it was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain PtZn / Mg(Al)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, the actual Zn content was 0.5 wt%, and the particle size of the PtZn intermetallic compound was 1.8 nm.

[0092] Comparative Example 3

[0093] Step A: Synthesize the hydrotalcite precursor MgAl-LDHs using a coprecipitation method. First, weigh 0.45 mmol of Mg(N) ·6 O, 0.15 mmol Al(N) )3.9 First, prepare a mixed salt solution. Next, weigh 0.11 mmol NaOH and 0.03 mmol Na₂CO₃ to prepare a mixed alkali solution. Slowly add the mixed salt and mixed alkali solutions simultaneously dropwise to a three-necked flask containing deionized water, maintaining the pH of the system at 10. The crystallization temperature is 65℃, and the crystallization time is 12 h. Afterward, filter the solid-liquid mixture and wash with deionized water until neutral. Then, dry the solid in an oven at 120℃ overnight to obtain MgAl-LDHs.

[0094] Step B: An equal volume of Pt(NH3)4(NO3)2 (0.08 mol / L concentration) solution was impregnated into a round-bottom flask containing the MgAl-LDHs prepared in step (A). The flask was shaken thoroughly for 30 min and then dried at 120℃ for 2 h to obtain Pt. 2+ / MgAl-LDHs.

[0095] Step C: The Pt prepared in step (B) 2+ 0.1 mL of silica sol was added to MgAl-LDHs to prepare a hydrotalcite precursor solution. Then, SiC-Foam-90ppi was fixed on the vacuum adsorption rotating stage of a spin coater, ensuring the SiC-Foam substrate was centered and stable. Subsequently, the Pt-loaded hydrotalcite precursor solution was dropwise added to the SiC-Foam surface. The equipment was started, causing the substrate to rotate at high speed with the rotating stage. Centrifugal force was used to rapidly spread and uniformly adhere the precursor solution to the substrate surface, while excess solution was ejected under centrifugal force. Finally, a uniform thin film layer was formed on the SiC-Foam surface, yielding Pt. 2+ / MgAl-LDHs / SiC-Foam-90ppi.

[0096] Step D: The Pt prepared in step (C) 2+ The / MgAl-LDHs / SiC-Foam-90ppi was placed in a tube furnace and calcined at 600℃ for 2 h in a N2 atmosphere with a heating rate of 2℃ / min and an N2 flow rate of 40 mL / min. Then, it was directly switched to H2 at a flow rate of 40 mL / min and reduced at 600℃ for 2 h to obtain Pt / Mg(Al)O / SiC-Foam-90ppi. The actual Pt content was 0.30 wt%, and the Pt cluster particle size was 1.8 nm.

[0097] Application Examples 1-9

[0098] The catalysts prepared in Examples 1-9 were used for propane dehydrogenation reactions. The propane dehydrogenation conditions included: in-situ Joule heating mode (applying a DC voltage to the conductive catalyst, utilizing the Joule effect of the catalyst resistance to achieve rapid in-situ heating; specific voltage and current values ​​are shown in Table 1); reaction temperature of 525°C; reaction pressure of atmospheric pressure; reaction feed of C3H8, Ar, and H2, with a molar ratio of C3H8∶H2∶Ar = 2∶1∶4; and propane mass hourly space velocity of 25 h⁻¹. -1 The catalyst dosage was 0.02 g. The reaction results are shown in Table 1.

[0099] Application Comparative Examples 1-3

[0100] The catalysts prepared in Comparative Examples 1-3 were used for propane dehydrogenation reactions. The propane dehydrogenation conditions included: in-situ Joule heating mode (applying DC voltage to the conductive catalyst, utilizing the Joule effect of the catalyst resistance to achieve rapid in-situ heating; specific voltage and current values ​​are shown in Table 1); reaction temperature of 525℃; reaction pressure of atmospheric pressure; reaction feed of C3H8, Ar, and H2, with a molar ratio of C3H8∶H2∶Ar = 2∶1∶4; and propane mass hourly space velocity of 25 h⁻¹. -1 The catalyst dosage was 0.02 g. The reaction results are shown in Table 1.

[0101] Application Comparative Example 4

[0102] The catalyst prepared in Example 1 was used for propane dehydrogenation. The propane dehydrogenation conditions included: conventional thermal heating mode, reaction temperature of 525°C; reaction pressure of atmospheric pressure; feed of C3H8, Ar, and H2, with a molar ratio of C3H8∶H2∶Ar = 2∶1∶4; and propane mass hourly space velocity of 25 h⁻¹. -1 The catalyst dosage was 0.02 g. The reaction results are shown in Table 1.

[0103] Table 1

[0104] As shown in Table 1, compared with the comparative examples, the catalyst of the present invention has higher dehydrogenation activity. In addition, the specific activity of Examples 1-4 is even higher, which is due to the formation of PtM intermetallic compounds and oxides MO. x The interface structure allows it to maintain a high active site temperature under Joule heating while also exhibiting excellent electrical response. In particular, the PtZn / Mg(Zn)(Al)O / SiC-Foam-90ppi catalyst achieves a propane conversion of 32.8% and a propylene selectivity of 99.8% in the propane dehydrogenation reaction at 520℃, which is far higher than the equilibrium conversion at this temperature.

[0105] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A propane dehydrogenation catalyst suitable for in-situ Joule heating, characterized in that, The catalyst contains a conductive foam substrate and a catalyst layer coated on the substrate. The catalyst layer contains a composite metal oxide support Mg(M)(Al)O and an active center intermetallic compound PtM dispersed on the support. M in the support and the active center is Zn, In, Ga or Y.

2. The propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 1, wherein, The substrate is made of foamed silicon carbide, foamed carbon, foamed copper, or foamed aluminum, and the porosity of the substrate is 30-120 ppi.

3. The propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 1, wherein, The content of Pt is 0.1-0.5 wt% and the content of M is 0.1-10 wt% based on the total weight of the catalyst.

4. The propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 1, wherein, The particle size of the intermetallic compound PtM is 0.5-3 nm.

5. The method for preparing the propane dehydrogenation catalyst suitable for in-situ Joule heating as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: 1) Prepare hydrotalcite precursor MgAlM-LDHs by impregnating the hydrotalcite precursor with Pt precursor solution to obtain the precursor of the catalyst layer; 2) The precursor slurry of the catalyst layer is coated onto the substrate to obtain the catalyst precursor; 3) The precursor of the catalyst is calcined and reduced to obtain the catalyst.

6. The method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 5, wherein, In step 1), the Pt precursor solution is loaded using the initial wet impregnation method, and the mixture is shaken evenly during the impregnation process. Then, it is dried at 100-130℃ for 1-5 hours to obtain the precursor of the catalyst layer.

7. The method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 5, wherein, In step 2), the coating is carried out by spin coating. While the substrate is rotating, the precursor slurry of the catalyst layer is dropped onto the substrate surface to form a thin film layer. After drying, the catalyst precursor is obtained.

8. The method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 5, wherein, The calcination conditions include: calcination at 600-800℃ for 2-4 hours in a N2 atmosphere, with a heating rate of 1-10℃ / min and an N2 flow rate of 10-60mL / min.

9. The method for preparing a propane dehydrogenation catalyst suitable for in-situ Joule heating according to claim 5, wherein, The reduction conditions include: reduction at 600-800℃ in an H2 atmosphere for 2-4 h, with an H2 flow rate of 10-60 mL / min.

10. The application of the propane dehydrogenation catalyst suitable for in-situ Joule heating as described in any one of claims 1-4 in the propane dehydrogenation to propylene, characterized in that, The energy supply for propane dehydrogenation is in-situ Joule heating; preferably, the reaction temperature for propane dehydrogenation is 300-550℃; and the reaction pressure is atmospheric pressure.

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