Propane dehydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly discloses a propane dehydrogenation catalyst and a preparation method and application thereof. The catalyst is composed of a carrier, a Pt cluster and K, wherein the Pt cluster and the K are loaded on the carrier, and the carrier is an alumina carrier with limited Sn. The preparation method comprises the following steps: 1) modifying aluminum oxide with acid to construct an aluminum oxide carrier rich in Al defect sites; 2) precipitating Sn on the alumina carrier through composite alkali to obtain a Sn-limited alumina carrier; (3) loading the Pt precursor solution on the Sn-limited alumina carrier by adopting an impregnation method, and roasting in air to obtain a catalyst precursor; 4, the catalyst precursor is sequentially subjected to reduction treatment and chlorination treatment, and the catalyst is obtained.According to the catalyst, the Pt loading capacity is controlled to be at the ultralow level of 0.24 wt% while the excellent performance is kept, and an innovative solution is provided for energy efficiency improvement and industrial production of the propane dehydrogenation technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a propane dehydrogenation catalyst, and a preparation method and application of the propane dehydrogenation catalyst. Background Art

[0002] As a core raw material in the modern chemical industry chain, propylene is used in nearly every major industrial sector. Propylene is not only used to produce polymer materials such as polypropylene, acrylonitrile, and propylene oxide, but is also widely used in the petrochemical and fine chemical sectors, including acrylic acid and esters. As a fundamental raw material for the manufacture of the "three major synthetic materials" of plastics, rubber, and fibers, propylene production is a key indicator of a country's chemical industry capabilities. Industrially, propylene is primarily derived from catalytic cracking reactions in petroleum refining, as well as from the cracking of naphtha and light diesel. Direct propane dehydrogenation to propylene is a key non-petroleum-based approach to expanding propylene sources. Compared to traditional propane oxidative dehydrogenation, direct propane dehydrogenation technology not only improves overall yields but also reduces equipment investment costs, demonstrating broad application prospects. Currently, the majority of existing propane dehydrogenation units utilize UOP's Oleflex process, using a PtSn / Al2O3 catalyst. This process is highly sought after for its high efficiency and stability, providing a reliable solution for propylene production.

[0003] With the rapid and sustained growth in demand for propylene in both domestic and international markets, the design and preparation of high-performance Pt-based catalysts plays a vital role in the industrial production of propylene. Currently, although single Pt catalysts exhibit high activity in dehydrogenation reactions, they are prone to hydrogenolysis side reactions in actual applications, resulting in poor propylene selectivity and an inability to meet the needs of industrial production. Furthermore, while pursuing high activity, excessive Pt loading not only exacerbates the catalyst's carbon deposition problem but also reduces its stability, which has become a core problem restricting the large-scale industrial application of propane dehydrogenation processes. Therefore, the development of new Pt-based catalysts that achieve low Pt loading, high dispersion, and excellent selectivity and stability has become a key technical issue that the industry urgently needs to address. Summary of the Invention

[0004] In view of the above situation, the purpose of the present invention is to provide a propane dehydrogenation catalyst, its preparation method and application, by adjusting the acidity and alkalinity, specific surface area, pore structure of the catalyst support, and the metal-support interaction, optimizing the structural characteristics of the metal Pt site, and introducing an additive (such as Sn) to achieve improved activity and stability of the propane dehydrogenation catalyst.

[0005] A first aspect of the present invention provides a propane dehydrogenation catalyst, which comprises a support and Pt clusters and K supported on the support, wherein the support is a Sn-restricted alumina support.

[0006] A second aspect of the present invention provides a method for preparing the above-mentioned propane dehydrogenation catalyst, the preparation method comprising the following steps: 1) Alumina is modified with acid to construct an alumina support rich in Al defect sites; 2) Precipitate Sn on an alumina support using a composite alkali to obtain a Sn-restricted alumina support; 3) The Pt precursor solution was loaded onto a Sn-restricted alumina support by an impregnation method and then calcined in air to obtain a catalyst precursor; 4) The catalyst precursor is subjected to reduction treatment and chlorination treatment in sequence to obtain a catalyst.

[0007] The third aspect of the present invention provides the use of the above catalyst in the dehydrogenation of propane to propylene.

[0008] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses for the first time a novel catalyst system based on the synergistic effect of lattice confinement and a metal support. Its core consists of two components: 1) the preparation of an ultra-uniform Sn lattice-confined alumina support, in which atomically dispersed Sn species are stably embedded on the alumina support surface through a lattice anchoring effect. 2) Utilizing the strong Pt-Sn interaction formed during topological transformation, the controllable preparation of uniform, highly dispersed, and highly stable Pt clusters is achieved. The innovative design of this catalyst results in high performance, exhibiting high activity, high propylene selectivity, and high stability in propane dehydrogenation reactions. Furthermore, its controllable synthesis facilitates its industrial application.

[0009] 2) The catalyst of the present invention maintains excellent performance in the propane dehydrogenation reaction while controlling the Pt loading at an ultra-low level of 0.24wt%. This not only significantly reduces the cost of precious metal use, but also fundamentally solves industry problems such as increased carbon deposition and decreased stability caused by excessive Pt loading, providing a solution for the greener and more economical upgrade of the propane dehydrogenation process.

[0010] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0011] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0012] According to a first aspect of the present invention, the present invention provides a propane dehydrogenation catalyst, which comprises a support and Pt clusters and K supported on the support, wherein the support is a Sn-restricted alumina support.

[0013] In the present invention, based on the total weight of the catalyst, the Pt loading amount can be 0.1-0.5wt%, preferably less than 0.3wt%, for example 0.24wt%; the Sn loading amount can be 0.3-2wt%, for example 0.51wt%; the K loading amount can be 0.3-2wt%, for example 0.24wt%.

[0014] According to the present invention, the particle size of Pt may be 0.5-2.5 nm, preferably less than or equal to 1 nm, and Pt exists on the carrier in the form of a monolayer dispersed Pt cluster.

[0015] In the present invention, the carrier can be prepared by the following method: modifying alumina with acid to construct an alumina carrier rich in Al defect sites; and precipitating Sn on the alumina carrier with a composite base to obtain a Sn-restricted alumina carrier.

[0016] Preferably, the composite alkali precipitation of Sn comprises: loading a Sn precursor solution on an alumina carrier, drying the carrier, then adding a composite alkali solution, and soaking and precipitating the carrier.

[0017] According to the present invention, the acid can be selected from at least one of hydrochloric acid, oxalic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid and citric acid, preferably at least one of hydrochloric acid, oxalic acid and acetic acid, more preferably a mixed acid formed by hydrochloric acid, oxalic acid and acetic acid, and the ratio of the mixed acid can be any ratio, preferably 1:1:1.

[0018] In the present invention, the composite alkali contains urea and a potassium compound, and the potassium compound can be selected from at least one of potassium carbonate, potassium hydroxide, potassium acetate, potassium nitrate, potassium sulfate, potassium chloride, potassium oxalate and potassium sulfate, preferably at least one of potassium carbonate, potassium hydroxide, potassium acetate and potassium nitrate.

[0019] According to a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned propane dehydrogenation catalyst, the preparation method comprising the following steps: 1) Alumina is modified with acid to construct an alumina support rich in Al defect sites; 2) Precipitate Sn on an alumina support using a composite alkali to obtain a Sn-restricted alumina support; 3) The Pt precursor solution was loaded onto a Sn-restricted alumina support by an impregnation method and then calcined in air to obtain a catalyst precursor; 4) The catalyst precursor is subjected to reduction treatment and chlorination treatment in sequence to obtain a catalyst.

[0020] In step 1) of the present invention, the acid may be selected from at least one of hydrochloric acid, oxalic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, and citric acid, preferably at least one of hydrochloric acid, oxalic acid, and acetic acid, and more preferably a mixed acid of hydrochloric acid, oxalic acid, and acetic acid. The ratio of the mixed acid may be any ratio, preferably 1:1:1. The concentration of the acid may be 1.0-5.0 mol / L.

[0021] Preferably, step 1) comprises: soaking the aluminum oxide in acid and shaking for 0.5-5 hours.

[0022] The alumina in the present invention can be selected from various specifications of alumina commonly used in the art, and can be selected according to actual needs, such as alumina balls with 20-40 mesh.

[0023] According to the present invention, in step 2), the composite base comprises urea and a potassium compound. The potassium compound may be selected from at least one of potassium carbonate, potassium hydroxide, potassium acetate, potassium nitrate, potassium sulfate, potassium chloride, potassium oxalate, and potassium sulfate, and is preferably at least one of potassium carbonate, potassium hydroxide, potassium acetate, and potassium nitrate. The concentration of the urea may be 1.0-5.0 mol / L, and the concentration of the potassium compound may be 0.01-0.5 mol / L.

[0024] Preferably, step 2) comprises: impregnating the alumina support with a Sn precursor solution, shaking for 0.5-5 hours, drying, then soaking in a composite alkali solution, heating to 80-100°C for 8-15 hours to complete precipitation, followed by drying and air calcination. The air calcination temperature is preferably 350-500°C and the time is preferably 1-5 hours. The Sn precursor solution can be a hydrochloric acid solution of SnCl4·4H2O, and its concentration can be 0.1 mol / L.

[0025] In step 3) of the present invention, the impregnation method is an incipient wetness impregnation method, specifically comprising: impregnating the Pt precursor solution and the Sn-restricted alumina support in equal volumes, shaking for 0.5-5 hours, such as 1 hour, to achieve uniform mixing, and then drying at 90-130°C for 1-5 hours, such as 120°C for 2 hours. The air calcination temperature is 500-800°C for 1-5 hours. The Pt precursor solution can be an H2PtCl6·6H2O solution, and its concentration can be 0.010 mol / L.

[0026] According to the present invention, in step 4), the reduction treatment conditions include: reduction at 400-800°C in a H2 atmosphere for 1-4 hours, preferably at 530°C, and preferably for 2 hours. The heating rate is 1-10°C / min, preferably 5°C / min, and the H2 space velocity is 200-2000h -1 , preferably 1000h -1 .

[0027] The chlorination conditions include: chlorination at 400-800 ° C for 1-4 hours in air and chlorine atmosphere, preferably 530 ° C, chlorination time is preferably 3 hours, air velocity is 200-2000h -1 , preferably 1300h -1 , chlorine space velocity is 1-50h -1 , preferably 8.3h -1 .

[0028] The present invention utilizes the aforementioned method of first modifying the support with a composite acid and then introducing the additives Sn and K with a composite base, followed by Pt loading, to produce a dehydrogenation catalyst with excellent performance. Sn is first anchored on a defect-rich alumina support, and then, through the strong interaction between Pt and Sn, a catalyst structure consisting of a single layer of highly dispersed Pt clusters is formed. The advantages of this design are reflected in the following aspects: Precise Control of Support Structure: Composite acid treatment modifies the alumina support to form a defect-rich alumina support. Composite alkali treatment precipitates Sn and evenly disperses it on the alumina support, while the addition of a K promoter enhances catalyst activity. The defect-rich alumina support anchors Sn through surface defect sites, achieving ultra-uniform, lattice-confined Sn loading, preventing Sn agglomeration and providing a stable support structure for subsequent Pt loading.

[0029] The performance advantages of single-layer highly dispersed Pt clusters: In the structural design of single-layer Pt clusters, the Pt atoms are fully exposed. This structure not only significantly improves the utilization of Pt atoms, but also greatly enhances the activity of the catalyst. The highly dispersed Pt clusters reduce the electronic interactions between Pt and Pt, while providing more active sites for reactant molecules, thereby improving the efficiency of the dehydrogenation reaction.

[0030] Enhanced stability due to strong Pt-Sn interactions: The uniform distribution of Sn on the alumina support surface modulates the electronic state of Pt through electronic effects. The strong interaction between Sn and Pt promotes uniform dispersion of Pt clusters and strengthens the bond between Pt and the support, significantly improving catalyst stability. During the reaction, the structural stability of the Pt clusters is maintained, thus preventing the decrease in activity caused by Pt agglomeration.

[0031] The catalyst structure of the present invention allows full exposure of Pt atoms, thereby improving atomic utilization and being more conducive to enhancing dehydrogenation activity.

[0032] According to a third aspect of the present invention, the present invention provides use of the above catalyst in the dehydrogenation of propane to propylene.

[0033] In the present invention, the reaction of propane dehydrogenation to propylene can adopt conventional materials and conditions in the prior art. For example, the catalyst loading amount is 0.6-6g, preferably 3g; the reaction feed contains propane, hydrogen and hydrogen sulfide, and the volume space velocity of propane is 10-2000h -1 , preferably 1000h -1 , the volume space velocity of hydrogen is 10-1000h -1 , preferably 500h -1 The volume space velocity of hydrogen containing 0.2% volume fraction of hydrogen sulfide is 1-100h -1 , preferably 60h -1 ; The reaction temperature is 550-650°C, preferably 610°C, and the reaction time is 5-24h, preferably 12h.

[0034] The substances and parameters not limited in the present invention can be selected according to the existing technology and belong to the conventional technical means in this field.

[0035] The present invention will be further described below with reference to the following examples, but is not limited to these examples.

[0036] The data of each embodiment and comparative example were obtained by the following method: Loading capacity: obtained by inductively coupled plasma spectrometry (ICP) detection using conventional methods; Inactivation rate constant k d : refers to the rate constant of the catalytic deactivation process, and the specific calculation method is ln[(1-X final ) / X final ]=k d *t + ln[(1-X intial ) / X intial ]. intial : Initial propane conversion, X final : Propane conversion at time t.

[0037] Example 1 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0038] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an oxalic acid solution of SnCl4·4H2O (concentration of 0.1 mol / L) with equal volume, and was shaken evenly with a vortex instrument for 1 h, and then dried at 120 ° C for 2 h to obtain the loaded Sn4+ Alumina Sn balls 4+ / Al 2-x O3.

[0039] Step C: Slowly add a mixed solution of 0.05 mol / L potassium carbonate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0040] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0041] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0042] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-1, whose actual Pt loading was 0.24wt%; the actual Sn loading was 0.51wt%; the actual K loading was 0.24wt%; and the Pt particle size was 1.0nm.

[0043] Example 2 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add 2.0 mol / L hydrochloric acid solution to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and hydrochloric acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0044] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina Sn balls 4+ / Al 2-x O3.

[0045] Step C: Slowly add a mixed solution of 0.05 mol / L potassium carbonate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0046] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0047] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0048] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530℃ in a H2 atmosphere for 2h, with a heating rate of 5℃ / min and a H2 air velocity of 1000 / h. After purging with N2 for 1h, chlorination was then carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-2, whose actual Pt loading was 0.24wt%; the actual Sn loading was 0.51wt%; the actual K loading was 0.24wt%; and the Pt particle size was 1.0nm.

[0049] Example 3 Step A: After drying, place alumina pellets (20-40 mesh) in a round-bottom flask and add 2.0 mol / L oxalic acid solution to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and oxalic acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0050] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina Sn balls 4+ / Al 2-x O3.

[0051] Step C: Slowly add a mixed solution of 0.05 mol / L potassium carbonate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0052] Step D: The K / SnO2 / Al 2-xThe catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0053] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0054] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air space velocity was 1300 h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-3, whose actual Pt loading is 0.24wt%; the actual Sn loading is 0.51wt%; the actual K loading is 0.24wt%; and the Pt particle size is 1.0nm.

[0055] Example 4 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add 2.0 mol / L acetic acid solution and completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and acetic acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0056] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina balls Sn 4+ / Al 2-x O3.

[0057] Step C: Slowly add a mixed solution of 0.05 mol / L potassium carbonate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-xThe pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0058] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0059] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0060] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530℃ in a H2 atmosphere for 2h, with a heating rate of 5℃ / min and a H2 air velocity of 1000 / h. After purging with N2 for 1h, chlorination was then carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-4, whose actual Pt loading is 0.24wt%; the actual Sn loading is 0.51wt%; the actual K loading is 0.24wt%; and the Pt particle size is 1.0nm.

[0061] Example 5 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0062] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina balls Sn 4+ / Al 2-x O3.

[0063] Step C: Slowly add a mixed solution of 0.05 mol / L potassium hydroxide and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0064] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0065] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0066] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1, and chlorination treatment for 3 hours to prepare catalyst KLDH-5, whose actual Pt loading is 0.24wt%; the actual Sn loading is 0.51wt%; the actual K loading is 0.24wt%; and the Pt particle size is 1.0nm.

[0067] Example 6 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0068] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina Sn balls 4+ / Al 2-x O3.

[0069] Step C: Slowly add a mixed solution of 0.05 mol / L potassium acetate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0070] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0071] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0072] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-6, whose actual Pt loading is 0.24wt%; the actual Sn loading is 0.51wt%; the actual K loading is 0.24wt%; and the Pt particle size is 1.0nm.

[0073] Example 7 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0074] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina Sn balls 4+ / Al 2-x O3.

[0075] Step C: Slowly add a mixed solution of 0.05 mol / L potassium nitrate and 3.0 mol / L urea to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-xO3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0076] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0077] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0078] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-7, in which the actual loading amount of Pt is 0.24wt%; the actual loading amount of Sn is 0.51wt%; the actual loading amount of K is 0.24wt%; and the particle size of Pt is 1.0nm.

[0079] Comparative Example 1 Step A: After drying, alumina pellets (20-40 mesh) were placed in a round-bottom flask and immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L). The pellets were shaken evenly with a vortex for 1 h and then dried at 120 ° C for 2 h to obtain the loaded Sn. 4+ Alumina Sn balls 4+ / Al 2-x O3, slowly add 0.05mol / L potassium carbonate and 3.0mol / L urea mixed solution into Sn 4+ / Al2O3, completely immerse the ball, heat to 90℃ and treat for 10h. After precipitation, dry at 120℃ for 2h to obtain K + / Sn 4+ / Al2O3. K + / Sn 4+ / Al2O3 was placed in a tubular heating furnace and calcined at 450°C in an air atmosphere for 2 h at a heating rate of 10°C / min to obtain K-SnO2 / Al2O3.

[0080] Step B: The round-bottom flask containing K / SnO2 / Al2O3 prepared in step (A) was vacuum-impregnated with H2PtCl6·6H2O solution (concentration of 0.010 mol / L), shaken evenly for 1 hour, and dried at 120℃ for 2 hours to obtain the catalyst precursor K-Pt 2+ / SnO2 / Al2O3.

[0081] Step C: K-Pt prepared in step (B) 2+ / SnO2 / Al2O3 was placed in a tubular heating furnace and calcined at 650℃ in an air atmosphere for 2h with a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al2O3.

[0082] Step D: The K-PtO2 / SnO2 / Al2O3 prepared in step (C) was placed in a tubular heating furnace and reduced at 530°C for 2 h in a H2 atmosphere with a heating rate of 5°C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-D1, whose actual Pt loading is 0.24wt%; the actual Sn loading is 0.51wt%; the actual K loading is 0.24wt%; and the Pt particle size is 1.4nm.

[0083] Comparative Example 2 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0084] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina Sn balls 4+ / Al2-x O3.

[0085] Step C: Slowly add 0.05 mol / L potassium carbonate solution to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Sn 4+ / Al 2-x O3. K + / Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K-SnO2 / Al 2-x O3.

[0086] Step D: The K / SnO2 / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / SnO2 / Al 2-x O3.

[0087] Step E: K-Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / SnO2 / Al 2-x O3.

[0088] Step F: K-PtO2 / SnO2 / Al prepared in step (E) 2-x O3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-D2, in which the actual loading amount of Pt is 0.24wt%; the actual loading amount of Sn is 0.51wt%; the actual loading amount of K is 0.24wt%; and the particle size of Pt is 1.0nm.

[0089] Comparative Example 3 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0090] Step B: Prepared in step (A) of the Al 2-x The round-bottom flask of the O3 carrier was immersed in an equal volume of SnCl4·4H2O hydrochloric acid solution (concentration of 0.1 mol / L), and was shaken evenly with a vortex instrument for 1 hour, and then dried at 120℃ for 2 hours to obtain the loaded Sn 4+ Alumina balls Sn 4+ / Al 2-x O3.

[0091] Step C: Slowly add 3.0 mol / L urea solution to the Sn prepared in step (B). 4+ / Al 2-x The pellets were completely immersed in O3 and heated to 90°C for 10 hours. After precipitation, they were dried at 120°C for 2 hours to obtain Sn 4+ / Al 2-x O3. Prepare Sn 4+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain SnO2 / Al 2-x O3.

[0092] Step D: Prepared in step (C) / SnO2 / Al 2-x The round-bottom flask containing O3 was vacuum-impregnated with H2PtCl6·6H2O solution (concentration 0.010 mol / L), shaken evenly for 1 h, and dried at 120 ° C for 2 h to obtain the catalyst precursor Pt 2+ / SnO2 / Al 2-x O3.

[0093] Step E: Pt prepared in step (D) 2+ / SnO2 / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain PtO2 / SnO2 / Al 2-x O3.

[0094] Step F: PtO2 / SnO2 / Al prepared in step (E) 2-xO3 was placed in a tubular heating furnace and reduced at 530℃ in a H2 atmosphere for 2h, with a heating rate of 5℃ / min and a H2 air velocity of 1000 / h. After purging with N2 for 1h, chlorination was then carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-D3, in which the actual Pt loading amount is 0.24wt% and the actual Sn loading amount is 0.51wt% and the Pt particle size is 1.3nm.

[0095] Comparative Example 4 Step A: Dry the alumina pellets (20-40 mesh) and place them in a round-bottom flask. Add a 2.0 mol / L mixed acid solution (hydrochloric acid concentration: oxalic acid concentration: acetic acid concentration = 1:1:1) to completely immerse the pellets. Shake on a shaker for 2 hours to mix the pellets and the mixed acid evenly to obtain Al-rich Al defect sites. 2-x O3 carrier.

[0096] Step B: Slowly add a mixed solution of 0.05 mol / L potassium carbonate and 3.0 mol / L urea to the Al prepared in step (A). 2-x The pellets were completely immersed in O3 and heated to 90℃ for 10h. After precipitation, they were dried at 120℃ for 2h to obtain K + / Al 2- x O3. K + / Al 2-x O3 was placed in a tubular heating furnace and calcined at 450℃ for 2h in an air atmosphere with a heating rate of 10℃ / min to obtain K / Al 2-x O3.

[0097] Step C: The K / Al 2-x The catalyst precursor K-Pt was obtained by vacuum impregnating an equal volume of H2PtCl6·6H2O solution (concentration 0.010 mol / L) in a round-bottom flask containing O3, shaking evenly for 1 h, and drying at 120 ° C for 2 h. 2+ / Al 2-x O3.

[0098] Step D: K-Pt prepared in step (C) 2+ / Al 2-x O3 was placed in a tubular heating furnace and calcined at 650℃ for 2h in an air atmosphere at a heating rate of 10℃ / min to obtain K-PtO2 / Al 2-x O3.

[0099] Step E: K-PtO2 / Al prepared in step (D) 2-xO3 was placed in a tubular heating furnace and reduced at 530 °C in a H2 atmosphere for 2 h, with a heating rate of 5 °C / min and a H2 space velocity of 1000 h -1 After purging with N2 for 1 hour, chlorination treatment was carried out. The air velocity was 1300h -1 , the chlorine space velocity is 8.3h -1 , and chlorination treatment for 3 hours to prepare catalyst KLDH-D4, in which the actual loading amount of Pt is 0.24wt%, the actual loading amount of K is 0.24wt%, and the particle size of Pt is 1.5nm.

[0100] The granular catalysts prepared in the examples and comparative examples were loaded into a fixed bed reactor and pretreated by introducing H2 at a H2 space velocity of 1000 h -1 , maintained at 530℃ for 2h; then the reaction feed was introduced for catalytic reaction, the reaction temperature was 610℃, the reaction pressure was normal pressure, and the volume space velocity (GHSV) of the reaction feed propane was 1000h -1 , hydrogen volume space velocity 500h -1 , sulfur-containing hydrogen (volume fraction 0.2% H2S) volume space velocity 60h -1 The catalyst dosage was 3 g. The H2S content at the tail gas outlet was controlled at 40-60 ppm. The catalytic performance for the propane dehydrogenation reaction is shown in Table 1.

[0101] Table 1 As can be seen from Table 1, the catalyst of the present invention has higher propane conversion, propylene selectivity and stability compared with the comparative example. From the root cause of the performance improvement, this is mainly due to the precise control of the support surface structure by the treatment with composite acid and composite base, and the synergistic optimization of the strong Pt-Sn interaction. Specifically, the present invention successfully achieved the preparation of ultra-uniform Sn lattice-restricted alumina by constructing Al defect sites on the support surface. By utilizing the strong Pt-Sn interaction formed during the topological transformation, uniform, highly dispersed, and low-loaded Pt clusters were prepared. This design has multiple advantages: First, the alumina support after composite acid treatment has more Al defect sites, thereby enhancing the support's ability to anchor metals or additives. Second, while the composite base precipitates Sn, the additive K is introduced, and Sn is uniformly distributed on the support, achieving ultra-uniform lattice-restricted Sn loading; third, the strong Pt-Sn interaction helps stabilize the structure of the Pt cluster, giving the catalyst better stability; fourth, the lattice matching and electronic interaction between Sn and the Al support also further optimize the performance of the catalyst. This multi-level regulation strategy not only achieves efficient catalysis at a lower Pt loading, but also provides a feasible way to reduce the use of precious metals and improve the economic efficiency of industrial applications.

[0102] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not 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, characterized in that The catalyst consists of a support and Pt clusters and K supported on the support, wherein the support is a Sn-limited alumina support.

2. The propane dehydrogenation catalyst according to claim 1, wherein Based on the total weight of the catalyst, the Pt loading is 0.1-0.5wt%, the Pt particle size is 0.5-2.5nm; the Sn loading is 0.3-2wt%; and the K loading is 0.3-2wt%.

3. The propane dehydrogenation catalyst according to claim 1, wherein The carrier is prepared by the following method: modifying alumina with acid to construct an alumina carrier rich in Al defect sites; Sn is precipitated on an alumina support by a complex alkali to obtain a Sn-limited alumina support; Preferably, the composite alkali precipitation of Sn comprises: loading a Sn precursor solution on an alumina carrier, drying the carrier, then adding a composite alkali solution, and soaking and precipitating the carrier.

4. The propane dehydrogenation catalyst according to claim 3, wherein The acid is selected from at least one of hydrochloric acid, oxalic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid and citric acid, preferably at least one of hydrochloric acid, oxalic acid and acetic acid, more preferably a mixed acid formed by hydrochloric acid, oxalic acid and acetic acid; The composite alkali contains urea and a potassium compound, wherein the potassium compound is selected from at least one of potassium carbonate, potassium hydroxide, potassium acetate, potassium nitrate, potassium sulfate, potassium chloride, potassium oxalate and potassium sulfate, and is preferably at least one of potassium carbonate, potassium hydroxide, potassium acetate and potassium nitrate.

5. The method for preparing the propane dehydrogenation catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: 1) Alumina is modified with acid to construct an alumina support rich in Al defect sites; 2) Precipitate Sn on an alumina support using a composite alkali to obtain a Sn-restricted alumina support; 3) The Pt precursor solution was loaded onto a Sn-restricted alumina support by an impregnation method and then calcined in air to obtain a catalyst precursor; 4) The catalyst precursor is subjected to reduction treatment and chlorination treatment in sequence to obtain a catalyst.

6. The method for preparing a propane dehydrogenation catalyst according to claim 5, wherein: In step 1), the acid is selected from at least one of hydrochloric acid, oxalic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid and citric acid, preferably at least one of hydrochloric acid, oxalic acid and acetic acid, more preferably a mixed acid formed by hydrochloric acid, oxalic acid and acetic acid; the concentration of the acid is 1.0-5.0 mol / L; Preferably, step 1) comprises: soaking the aluminum oxide in acid and shaking for 0.5-5 hours.

7. The method for preparing a propane dehydrogenation catalyst according to claim 5, wherein: In step 2), the composite base contains urea and a potassium compound, wherein the potassium compound is selected from at least one of potassium carbonate, potassium hydroxide, potassium acetate, potassium nitrate, potassium sulfate, potassium chloride, potassium oxalate, and potassium sulfate, and preferably at least one of potassium carbonate, potassium hydroxide, potassium acetate, and potassium nitrate; the concentration of the urea is 1.0-5.0 mol / L, and the concentration of the potassium compound is 0.01-0.5 mol / L; Preferably, step 2) comprises: impregnating the alumina support with a Sn precursor solution, shaking for 0.5-5 hours, drying, then soaking in a composite alkali solution, heating to 80-100°C for 8-15 hours until precipitation is complete, and then drying and air calcining. The air calcination temperature is preferably 350-500°C and the time is preferably 1-5 hours.

8. The method for preparing a propane dehydrogenation catalyst according to claim 5, wherein: In step 3), the impregnation method is an incipient wetness impregnation method, which comprises: impregnating the Pt precursor solution and the Sn-restricted alumina support in equal volumes, shaking for 0.5-5 hours, and then drying at 90-130° C. for 1-5 hours; The air roasting temperature is 500-800°C and the time is 1-5h.

9. The method for preparing a propane dehydrogenation catalyst according to claim 5, wherein: In step 4), the reduction treatment conditions include: reduction at 400-800 ° C in H2 atmosphere for 1-4 hours, a heating rate of 1-10 ° C / min, and a H2 space velocity of 200-2000h -1 ; The chlorination conditions include: chlorination at 400-800℃ for 1-4h in air and chlorine atmosphere, with an air velocity of 200-2000h -1 , chlorine space velocity is 1-50h -1 .

10. Use of the catalyst according to any one of claims 1 to 4 in the dehydrogenation of propane to propylene; Preferably, the loading amount of the catalyst is 0.6-6 g; the reaction feed contains propane, hydrogen and hydrogen sulfide, and the volume space velocity of propane is 10-2000 h -1 , the volume space velocity of hydrogen is 10-1000h -1 The volume space velocity of hydrogen containing 0.2% volume fraction of hydrogen sulfide is 1-100h -1 ; The reaction temperature is 550-650℃, and the reaction time is 5-24h.

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