Catalyst as well as preparation method and application thereof

Abstract

The invention discloses a catalyst as well as a preparation method and application thereof. The catalyst comprises a modified carrier, a main active component and an auxiliary component, the modified carrier is a CeOx modified carrier, and x is equal to 1-2; the carrier is selected from at least one of SiO2, Al2O3, TiO2 and an MFI molecular sieve carrier; the main active component comprises an active element Pt; the auxiliary agent component comprises a first auxiliary agent and a second auxiliary agent; the first auxiliary agent comprises a first auxiliary agent element; the first additive element is selected from at least one of IIIA elements; the second auxiliary agent comprises a second auxiliary agent element; the second additive element is selected from at least one of an alkali metal element, an alkaline earth metal element and a transition metal element. The catalyst is applied to propylene preparation reaction through propane dehydrogenation, and has the characteristics of long one-way service life, low carbon deposition rate, difficult sintering of active components, high propylene selectivity and stability and the like.

Description

Technical Field

[0001] This application relates to a catalyst, its preparation method, and its application, and belongs to the field of catalysis. Background Art

[0002] Propylene is an important basic chemical raw material and petrochemical intermediate used in the production of polypropylene, propylene oxide, butanol, phenol, propylene glycol, acetone, acrylic acid, acrylonitrile, octanol, and isopropanol. Currently, traditional propylene production processes cannot meet demand. In recent years, with the large-scale development of shale gas and Middle Eastern natural gas, propane direct dehydrogenation (PDH) technology has received increasing attention. This technology has advantages such as a short process, high yield, few byproducts, and low investment cost. Among existing and planned propane dehydrogenation industrial plants in China, the trend of using the Oleflex process is becoming increasingly apparent. This is closely related to the use of Pt-based catalysts, which are not only non-toxic but also exhibit higher propane dehydrogenation activity, product selectivity, and catalytic stability than processes such as Catofin, STAR, and LINDE.

[0003] Despite the significant achievements, platinum-based PDH catalysts still face two serious challenges: 1) Platinum is expensive, and improving its atom utilization rate is undoubtedly essential to reducing costs; 2) PDH reactions require high-temperature operation, accompanied by side reactions such as hydrogenolysis, isomerization, and coking, which not only lead to carbon buildup but also cause the active components to sinter. It is worth noting that, unlike carbon buildup, the sintering of the active components is irreversible.

[0004] Improving the dispersion of Pt species is an effective way to enhance atom utilization. In particular, the PDH reaction is a structure-sensitive reaction; reducing the size of metal particles will increase the surface free energy of metal atoms, and its catalytic activity will also be greatly improved.

[0005] To improve platinum dispersion, previous researchers have proposed many strategies. Firstly, from the perspective of support modification, increasing metal-support interactions is crucial. For example, Pt species can be highly dispersed on Al(V)-rich Al₂O₃ nanosheets through Pt-Al(V) interactions. However, Pt aggregation remains inevitable as the PDH reaction proceeds. Secondly, from the perspective of adding promoters, Pt is alloyed with transition metals to maintain high Pt dispersion through physical isolation or partial coverage. For example, by modifying with a trace amount of platinum (0.1 wt.%), transition metal-based catalysts with high PDH activity can be obtained. These geometrically isolated and electron-rich Pt sites in the alloy can promote the cleavage of the first and second CH groups of propane while inhibiting deep dehydrogenation of propylene. However, due to the sintering tendency of the active component, these low-load platinum-based catalysts typically deactivate rapidly, exhibiting poor stability.

[0006] Numerous patents have been reported regarding the modification of alkane dehydrogenation catalyst supports or additives, such as US patents US2014275686A1 and US2013072739A1; and Chinese patents CN116212861A, CN116943646A, CN104289220A, and CN103787810A. Domestic and international research institutions and users have been continuously researching alkane dehydrogenation catalysts with high catalytic activity and high stability. However, much research has been limited to focusing on the additive components and loading methods used to dilute the active component by forming alloys, thereby improving Pt dispersion. Modification of the support has been limited to alumina prepared by different methods to increase its specific surface area, and to doping the alumina to improve its acidity.

[0007] It is worth noting that a 2022 report (Nature, 611, 284-288 (2022)) indicated that confining atomically dispersed Pt / Pd / Rh atoms to oxide nanoclusters or "nano islands" can enhance the anchoring effect, with the nano islands themselves dispersed and fixed on a robust high-surface-area carrier. At optimized pH values, aqueous platinum chloride anions react with positively charged CeO₂... x Nano-islands are formed, but not with negatively charged SiO2. Heat treatment removes chlorides without compromising dispersibility or stability. Furthermore, research (Science, 383, 998-1004 (2024)) shows that In can enhance the dispersibility of Rh species through geometric effects. However, research on how to improve the dispersibility of Pt species using appropriate methods to couple the carrier confinement effect and the geometric effect of the additives for PDH reaction systems remains lacking. Summary of the Invention

[0008] To address the problems existing in the prior art, this application proposes a catalyst, its preparation method, and its application. A CeO-rich catalyst was prepared using a strategy of uniform oxidative dispersion. x The modified support of (x=1~2) nano-islands, with the main active component Pt loaded via liquid-phase electrostatic adsorption and impregnated with two auxiliary agents, increases the catalyst's dispersibility. The catalyst, applied to the propane dehydrogenation to propylene reaction, exhibits characteristics such as long single-pass life, low coking rate, resistance to sintering of the active component, and high selectivity and stability for propylene.

[0009] According to one aspect of this application, a catalyst is provided, the catalyst comprising a modified support, a main active component, and an auxiliary component;

[0010] The modified carrier is CeO x The modified carrier, wherein x = 1 to 2;

[0011] The support is selected from at least one of SiO2, Al2O3, TiO2, and MFI molecular sieve supports;

[0012] The main active component includes the active element Pt;

[0013] The auxiliary component includes a first auxiliary agent and a second auxiliary agent;

[0014] The first auxiliary agent includes a first auxiliary agent element;

[0015] The first auxiliary element is selected from at least one of elements IIIA;

[0016] The second auxiliary agent includes a second auxiliary agent element;

[0017] The second auxiliary element is selected from at least one of alkali metal elements, alkaline earth metal elements, and transition metal elements.

[0018] Optionally, the IIIA element is selected from at least one of B, Ga, and In.

[0019] Preferably, the IIIA element is In.

[0020] Optionally, the alkali metal element is selected from at least one of Na and K.

[0021] Preferably, the alkali metal element is K.

[0022] Optionally, the alkaline earth metal element is selected from at least one of Mg and Ca.

[0023] Preferably, the alkaline earth metal element is Mg.

[0024] Optionally, the transition metal element is selected from at least one of Fe, Cu, Zn, W, Cr, Mo, Co, Mn, and Ni.

[0025] Optionally, in the modified support, CeO x The mass fraction of CeO is 1% to 50% of the carrier mass. x Its quality is calculated based on its own mass;

[0026] Optionally, in the modified support, CeO x The mass fraction is the carrier mass ratio independently selected from any value among 1%, 5%, 10%, 12%, 15%, 20%, 24%, 25%, 30%, 35%, 40%, 45%, and 50%, or a range between any two of the above points.

[0027] Optionally, the loading of the main active component is 0.1% to 1.0% of the carrier mass based on the weight of Pt element.

[0028] Optionally, the loading amount of the main active component, measured by the weight of Pt element, is independently selected from any value among 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, and 1.0%, or a range between any two of the above points.

[0029] Preferably, the loading of the main active component is 0.3% to 0.7% of the carrier mass based on the weight of Pt element.

[0030] Optionally, the loading of the first auxiliary agent is 0.1% to 5.0% of the carrier mass based on the elemental weight of the first auxiliary agent.

[0031] Optionally, the loading amount of the first adjuvant, based on the elemental weight of the first adjuvant, is independently selected from any value among 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, and 5.0%, or a range between any two of the above points.

[0032] Preferably, the loading of the first auxiliary agent is 0.5% to 3.0% of the carrier mass based on the elemental weight of the first auxiliary agent.

[0033] Optionally, the loading of the second auxiliary agent is 0.1% to 10.0% of the carrier mass based on the elemental weight of the second auxiliary agent.

[0034] Optionally, the loading amount of the second adjuvant, based on the elemental weight of the second adjuvant, is independently selected from any value among 0.1%, 0.2%, 0.5%, 0.6%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, and 10.0%, or a range between any two of the above points.

[0035] Preferably, the loading of the second auxiliary agent is 0.2% to 5.0% of the carrier mass based on the elemental weight of the second auxiliary agent.

[0036] Optionally, the weight ratio of the loading amount of the first adjuvant to the loading amount of the main active component is 0.25:1 to 6:1.

[0037] Optionally, the weight ratio of the loading amount of the first adjuvant to the loading amount of the main active component is independently selected from any value among 0.25:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1 or a range between any two of the above points.

[0038] Preferably, the weight ratio of the loading amount of the first auxiliary agent to the loading amount of the main active component is 0.5:1 to 4:1.

[0039] Optionally, the weight ratio of the loading amount of the second adjuvant to the loading amount of the main active component is 0.5:1 to 10:1.

[0040] Optionally, the weight ratio of the loading amount of the second adjuvant to the loading amount of the main active component is independently selected from any value among 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or a range between any two of the above points.

[0041] Preferably, the weight ratio of the loading amount of the second auxiliary agent to the loading amount of the main active component is 3:1 to 7:1.

[0042] Optionally, the specific surface area of ​​the modified carrier is 10 m². 2 / g~300m 2 / g.

[0043] According to another aspect of this application, a method for preparing the above-mentioned catalyst is provided, comprising the following steps:

[0044] A. Prepare a mixed solution a by mixing the carrier, water, and cerium source;

[0045] B. Add ammonia water to mixed solution a, dry I, calcine I to obtain the modified carrier;

[0046] C. Immerse the modified carrier in water, add acid solution to adjust the pH, and obtain solution b;

[0047] D. Add solution c containing the main active component precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor to solution b, dry II, and calcine II to obtain the catalyst.

[0048] Optionally, the support is selected from at least one of SiO2, Al2O3, TiO2, and MFI molecular sieve supports.

[0049] Optionally, the cerium source is selected from at least one of cerium nitrate, cerium oxalate, cerium carbonate, cerium chloride, and cerium sulfate.

[0050] Optionally, the acid in the acid solution includes inorganic acids and / or organic acids.

[0051] Optionally, the inorganic acid is hydrochloric acid.

[0052] Optionally, the organic acid is selected from at least one of citric acid, oxalic acid, lactic acid, malic acid, and acetic acid.

[0053] Optionally, the main active component precursor is selected from at least one of chloroplatinic acid, ammonium chloroplatinate, and tetraammineplatinum nitrate.

[0054] Optionally, the first auxiliary precursor is selected from at least one of boric acid, gallium nitrate, gallium chloride, indium nitrate, and indium chloride.

[0055] Optionally, the second auxiliary precursor is selected from at least one of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ferric chloride, copper chloride, zinc chloride, tungsten hexachloride, chromium chloride, molybdenum pentachloride, cobalt chloride, manganese chloride, and nickel chloride.

[0056] Optionally, in step C, the pH is adjusted to 3-6.

[0057] Optionally, the concentration of the ammonia water is 1 to 4 mol / L, and the molar ratio of ammonia water to cerium source is 3:1 to 6:1.

[0058] Optionally, the mass ratio of the cerium source to the support is 1 to 50:100, and the cerium source is CeO2. x For quality calculation, x = 1 to 2.

[0059] Optionally, the mass ratio of the cerium source to the carrier is independently selected from any value among 1:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100 or a range between any two of the above.

[0060] Optionally, the ratio of modified carrier to water in the modified carrier aqueous solution is 3 to 10 g / L.

[0061] Optionally, the rate at which solution c is added to solution b is 5–20 mL / h.

[0062] Optionally, the rate at which solution c is added to solution b is independently selected from any value among 5 mL / h, 10 mL / h, 15 mL / h, 20 mL / h, or a range between any two of the above points.

[0063] Optionally, the temperature of the drying process I is 20–60°C.

[0064] Optionally, the temperature of the drying process I is independently selected from any value among 20°C, 30°C, 40°C, 50°C, and 60°C, or a range between any two of the above points.

[0065] Optionally, the drying time of step I is 6 to 12 hours.

[0066] Optionally, the drying time of the first drying step is independently selected from any value among 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two of the above points.

[0067] Optionally, the roasting I is carried out in an oxygen-containing atmosphere.

[0068] Optionally, the temperature of roasting I is 500–600°C.

[0069] Optionally, the temperature of roasting I is independently selected from any value among 500℃, 525℃, 550℃, 575℃, and 600℃, or a range between any two of the above points.

[0070] Optionally, the roasting time of step I is 2 to 12 hours.

[0071] Optionally, the roasting time I is independently selected from any value among 2h, 4h, 6h, 8h, 10h, and 12h, or a range between any two of the above points.

[0072] Optionally, the temperature of the drying process II is 20–60°C.

[0073] Optionally, the temperature of the drying II is independently selected from any value among 20°C, 30°C, 40°C, 50°C, and 60°C, or a range between any two of the above points.

[0074] Optionally, the drying time for step II is 6 to 12 hours.

[0075] Optionally, the drying time II is independently selected from any value among 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two of the above points.

[0076] Optionally, the calcination II is carried out in an oxygen-containing atmosphere.

[0077] Optionally, the calcination temperature II is 500–600°C.

[0078] Optionally, the temperature of the roasting II is independently selected from any value among 500℃, 525℃, 550℃, 575℃, and 600℃, or a range between any two of the above points.

[0079] Optionally, the roasting time II is 2 to 12 hours.

[0080] Optionally, the roasting time II is independently selected from any value among 2h, 4h, 6h, 8h, 10h, and 12h, or a range between any two of the above points.

[0081] As a specific implementation method, a method for synthesizing the above-mentioned catalyst is provided, the specific steps of which are as follows:

[0082] A. The carrier powder is mixed with water, and the resulting aqueous solution is ultrasonically treated to obtain a homogeneous mixture solution. During vigorous stirring, CeO2 is added... x The cerium source, calculated by mass, is dissolved in the above mixture solution to prepare solution a;

[0083] B. Inject ammonia into solution a, stir for 1-10 minutes, vacuum filter, dry I, grind and calcine I to obtain the modified carrier;

[0084] C. Immerse the obtained modified carrier in deionized water, sonicate for 5-30 minutes, and adjust the pH to 3-6 by adding hydrochloric acid solution to obtain solution b containing the modified carrier;

[0085] D. Dissolve the main active component precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor in deionized water to prepare solution c. Under vigorous stirring, slowly pump solution c into solution b containing the modified support over a certain period of time, continue stirring, vacuum filter, wash the resulting precipitate with deionized water, dry it (II), and calcine it (II) to obtain the catalyst.

[0086] Optionally, in step B, a muffle furnace is used for roasting. The temperature is increased from room temperature (20-30°C) to 500-600°C in an air atmosphere at a programmed heating rate of 5-10°C, and then held at that temperature for 4-12 hours before being air-cooled to room temperature.

[0087] Optionally, in step D, the pumping time is 3-6 hours, the pumping rate is 5-20 mL / h, and the stirring time is 1-4 hours.

[0088] Optionally, in step D, a muffle furnace is used for roasting. The temperature is increased from room temperature (20-30°C) to 500-600°C in an air atmosphere at a programmed heating rate of 5-10°C, and then held at that temperature for 4-12 hours before being air-cooled to room temperature.

[0089] According to another aspect of this application, an application of the above-mentioned catalyst in the dehydrogenation of propane to propylene is provided, comprising the following steps: contacting a feed gas containing propane and hydrogen with a reduced catalyst, reacting, and obtaining propylene.

[0090] Optionally, the reduction is carried out in an atmosphere containing hydrogen.

[0091] Optionally, the hydrogen volume content in the hydrogen-containing atmosphere is 10-50%.

[0092] Optionally, the volume content of hydrogen in the mixed atmosphere is independently selected from any value of 10%, 20%, 30%, 40%, 50% or a range between any two of the above points.

[0093] Optionally, the reduction temperature is 450–600°C.

[0094] Optionally, the reduction temperature is independently selected from any value among 450°C, 500°C, 550°C, and 600°C, or a range between any two of the above points.

[0095] Optionally, the restoration time is 2 to 5 hours.

[0096] Optionally, the restoration time is independently selected from any value among 2h, 3h, 4h, and 5h, or a range between any two of the above points.

[0097] Optionally, the reaction temperature is 450℃~600℃, the reaction pressure is 0.05~0.5MPa, and the weight hourly space velocity of propane is 6~20h. -1 The hydrogen-hydrogen molar ratio is 0.25:1 to 10:1.

[0098] Optionally, the reaction is carried out in a fixed-bed reactor.

[0099] The single-pass lifetime described in this application refers to the time during which a catalyst maintains a certain activity level under operating conditions, wherein the activity level includes propane conversion and product selectivity. Specifically, the single-pass lifetime is calculated from the start of the reaction until either of these parameters can no longer be maintained stably.

[0100] The beneficial effects that this application can produce include:

[0101] (1) The catalyst provided in this application is prepared with CeO-rich material using a strategy of uniform oxidative dispersion. x The modified carrier of (x=1~2) nano islands loaded the main active component Pt through liquid phase electrostatic adsorption and impregnated with two auxiliary agents. The dispersion of Pt was increased by the carrier confinement effect and the geometric effect of the auxiliary agents, thus improving the atom utilization rate.

[0102] (2) The catalyst provided in this application has a synergistic effect between the two additives impregnated, which is beneficial to improving the dispersibility of Pt and reducing the coking rate.

[0103] (3) The catalyst provided in this application is used for the propane dehydrogenation to propylene reaction and has the characteristics of long single-pass life, low coking rate, non-sintering of active components, and high selectivity and stability of propylene. Attached Figure Description

[0104] Figure 1 The propane conversion rate test results are for catalyst A prepared in Comparative Example 2 of this application.

[0105] Figure 2 The results show the propylene selectivity test results of catalyst A prepared in Comparative Example 2 of this application.

[0106] Figure 3 The propane conversion rate test results are for catalyst B prepared in Example 7 of this application.

[0107] Figure 4 The results are the propylene selectivity test results for catalyst B prepared in Example 7 of this application.

[0108] Figure 5The propane conversion rate test results are for catalyst C prepared in Example 8 of this application.

[0109] Figure 6 The results are the propylene selectivity test results for catalyst C prepared in Example 8 of this application. Detailed Implementation

[0110] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0111] Unless otherwise specified, the raw materials and solvents used in the embodiments of this application were all purchased commercially.

[0112] The analysis method in the embodiments of this application is as follows:

[0113] The gaseous products of the reaction were analyzed online using an Agilent 7890 gas chromatograph (HP-Al2O3 / KCl capillary packed column, FID detector).

[0114] In the embodiments of this application, the propane conversion rate and propylene selectivity are calculated as follows:

[0115] In the embodiments of this application, the catalyst activity evaluation indicators, namely propane conversion and propylene selectivity, are calculated based on the number of carbon moles:

[0116] Propane conversion rate (%) = [n(propane)] in -n(propane) out ] / n(propane) in *100%

[0117] Propylene selectivity (%) = n(propylene) out / [n(propane) in -n(propane) out ]*100%

[0118] In the above formula, n (propane) in The molar content of propane in the introduced reaction gas is represented by n(propane). out This represents the molar content of propane and propylene in the reaction products.

[0119] Comparative Example 1: Preparation of Silica Support

[0120] 360 mg of SiO2 powder was mixed with 100 mL of deionized water, ultrasonically vibrated for 30 min, dried in an oven at 60 °C for 12 h, heated to 600 °C in an air atmosphere in a muffle furnace at a programmed heating rate of 10 °C / min and calcined for 12 h, and then air-cooled to room temperature to obtain a silicon oxide support.

[0121] Example 1: Preparation of Modified Carrier 1

[0122] Mix 360 mg of SiO2 powder with 100 mL of deionized water, sonicate for 30 min, and use this as a 100% carrier, CeO2... x The mass percentage content is 12%, and it will be in the form of CeO. x 0.4 mmol of Ce(NO3)3·6H2O was dissolved in the support solution and stirred until a homogeneous precursor solution was formed. 0.8 mL of ammonia (2M) was pumped into the above solution at a rate of 10 mL / h, stirred for 3 min, dried in a 60 °C oven for 12 h, and then calcined in an air-filled muffle furnace at a programmed heating rate of 10 °C / min from room temperature to 600 °C for 12 h. The calcined solution was then air-cooled to room temperature to obtain modified support 1.

[0123] Example 2: Preparation of Modified Carrier 2

[0124] Mix 360 mg of SiO2 powder with 100 mL of deionized water, sonicate for 30 min, and use this as a 100% carrier, CeO2... x The mass percentage content is 24%, and it will be in the form of CeO. x 0.8 mmol of Ce(NO3)3·6H2O was dissolved in the support solution and stirred until a homogeneous precursor solution was formed. 1.6 mL of ammonia water (2M) was pumped into the above solution at a rate of 10 mL / h, stirred for 3 min, dried in an oven at 60 °C for 12 h, and then calcined in an air atmosphere in a muffle furnace from room temperature to 600 °C at a programmed rate of 10 °C / min for 12 h. After air cooling to room temperature, modified support 2 was obtained.

[0125] Preparation of modified carriers 3-6 in Examples 3-6

[0126] The operation of modified supports 3 to 6 is the same as in Example 1, except that the type, concentration, and type of cerium source of the support are changed, as detailed in Table 1.

[0127] Table 1 Operating conditions for Examples 3-6

[0128]

[0129] Comparative Example 2: Preparation of Catalyst A

[0130] 300 mg of the SiO2 support obtained in the comparative example was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid, indium chloride, and potassium chloride (calculated by loading, 100% of the support) were dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, indium: 0.5 wt%, potassium: 0.3 wt%, denoted as catalyst A.

[0131] Example 7 Preparation of Catalyst B

[0132] 300 mg of modified support 1 was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid, indium chloride, and potassium chloride (calculated by loading, based on 100% of the support) were dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, indium: 0.5 wt%, potassium: 0.3 wt%, denoted as catalyst B.

[0133] Example 8 Preparation of Catalyst C

[0134] 300 mg of modified support 1 was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid, boric acid, and magnesium chloride (100% of the support, calculated by loading) were dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, boron: 0.3 wt%, magnesium: 0.3 wt%, denoted as catalyst C.

[0135] Examples 9-12: Preparation of catalysts D-G

[0136] The preparation of catalysts D to G is the same as in Example 7, except that the support is replaced with modified supports 3 to 6.

[0137] Preparation of catalyst H in Comparative Example 3

[0138] 300 mg of modified support 2 was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid, calculated based on the loading of the support (100% of the support), was dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, denoted as catalyst H.

[0139] Preparation of Catalyst I (Comparative Example 4)

[0140] 300 mg of modified support 2 was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid and indium chloride, calculated by loading (100% of the support), were dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, indium: 0.2 wt%, denoted as catalyst I.

[0141] Preparation of catalyst J in Comparative Example 5

[0142] 300 mg of modified support 2 was soaked in 70 mL of deionized water and sonicated for 30 min. The pH of the solution was adjusted to 4 by adding hydrochloric acid solution. Chloroplatinic acid and potassium chloride, calculated by loading (100% of the support), were dissolved in 50 mL of deionized water. The above impregnation solution was slowly pumped into the support solution over 5 h at a pumping rate of 10 mL / h, stirred for 2 h, vacuum filtered, washed 5 times with deionized water, and then dried in a 60 °C oven for 12 h. The dried sample was placed in a muffle furnace and calcined at 600 °C for 12 h in air. The resulting catalyst composition was: platinum: 0.5 wt%, potassium: 0.2 wt%, denoted as catalyst J.

[0143] Test Example 1: Characterization of N2 physisorption on the support

[0144] The pore size and specific surface area characteristics of the SiO2 support in Comparative Example 1, the modified support 1 in Example 1, and the modified support 2 in Example 2 were detected, and the results are detailed in Table 2.

[0145] The pore size and specific surface area of ​​the carrier were detected using nitrogen physical adsorption.

[0146] Table 2. Carrier characteristics

[0147] carrier Average pore size (nm) <![CDATA[Specific surface area (m 2 / g)]]> type Comparative Example 10 280 <![CDATA[SiO2]]> Modified carrier 1 8 240 <![CDATA[CeO x / SiO2]]> Modified carrier 2 7 200 <![CDATA[CeO x / SiO2]]>

[0148] Test Example 2: Characterization of N2 physisorption of the catalyst

[0149] The pore size and specific surface area characteristics of the catalysts prepared in Comparative Examples 2, 7-8, and 3-5 were detected, and the results are detailed in Table 3.

[0150] The pore size and specific surface area of ​​the catalyst were detected using nitrogen physical adsorption.

[0151] Table 3 Catalyst Characteristics

[0152] Catalyst number Average pore size (nm) <![CDATA[Specific surface area (m 2 / g)]]> type Catalyst A 8 270 <![CDATA[PtInK / SiO2]]> Catalyst B 7 250 <![CDATA[PtInK / CeO x / SiO2]]> Catalyst C 8 220 <![CDATA[PtBMg / CeO x / SiO2]]> catalyst H 8 200 <![CDATA[Pt / CeO x / SiO2]]> Catalyst I 7 160 <![CDATA[PtIn / CeO x / SiO2]]> Catalyst J 8 145 <![CDATA[PtK / CeO x / SiO2]]>

[0153] Test Example 3: Performance Evaluation of Propane Dehydrogenation Catalyst

[0154] The propane dehydrogenation performance of the catalysts prepared in Comparative Examples 2, 7-8, and 3-5 was evaluated in a quartz tubular fixed-bed reactor. The catalyst loading was 0.15 g (0.3 mL). Under H2 conditions, the temperature was increased to 600 °C at a rate of 5 °C / min, and reduction was carried out for 2 hours. Propane was then introduced, and the evaluation period was 24 hours. The reaction conditions were: temperature 600 °C, pressure 0.05 MPa, WHSV = 6 h. -1 The molar ratio of H2 to C3H8 is 0.5.

[0155] The reaction products were analyzed online using an Agilent 7890A gas chromatograph. The chromatographic conditions were: injection temperature 180℃, column oven temperature 105℃, FID detector temperature 200℃, and HP-Al2O3 / KCl column. The test results are detailed in Table 4.

[0156] Table 4. Results of propane conversion and propylene selectivity in the catalyst-catalyzed propane dehydrogenation reaction.

[0157]

[0158] As shown in Table 4, the catalyst described in this application improves propane conversion and propylene selectivity, and has a longer single-pass lifetime. This indicates that when applied to the propane dehydrogenation to propylene reaction, the catalyst exhibits a low coking rate and the active components are less prone to sintering. Figures 1-6 As can be seen, the catalyst provided by the present invention has the characteristics of high propane conversion, high propylene selectivity, and good stability.

[0159] Unless otherwise specified, all figures appearing in this application specification and claims, such as active components, temperature and time, conversion rates, etc., should not be construed as absolutely precise values. Due to the standard deviation of measurement techniques, the measured values ​​inevitably contain a certain degree of experimental error.

[0160] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A catalyst, characterized in that, The catalyst comprises a modified support, a main active component, and an auxiliary component; The modified carrier is CeO x The modified carrier, wherein x = 1 to 2; The support is selected from at least one of SiO2, Al2O3, TiO2, and MFI molecular sieve supports; The main active component includes the active element Pt; The auxiliary component includes a first auxiliary agent and a second auxiliary agent; The first auxiliary agent includes a first auxiliary agent element; The first auxiliary element is selected from at least one of elements IIIA; The second auxiliary agent includes a second auxiliary agent element; The second auxiliary element is selected from at least one of alkali metal elements, alkaline earth metal elements, and transition metal elements.

2. The catalyst according to claim 1, characterized in that, The IIIA element is selected from at least one of B, Ga, and In; The alkali metal element is selected from at least one of Na and K; The alkaline earth metal element is selected from at least one of Mg and Ca; The transition metal element is selected from at least one of Fe, Cu, Zn, W, Cr, Mo, Co, Mn, and Ni.

3. The catalyst according to claim 1, characterized in that, In the modified carrier, CeO x The mass fraction of CeO is 1% to 50% of the carrier mass. x Its quality is calculated based on its own mass; Preferably, the loading of the main active component is 0.1% to 1.0% of the carrier mass based on the weight of Pt element; The loading amount of the first auxiliary agent is 0.1% to 5.0% of the carrier mass based on the elemental weight of the first auxiliary agent; The loading amount of the second auxiliary agent is 0.1% to 10.0% of the carrier mass based on the elemental weight of the second auxiliary agent; Preferably, the weight ratio of the loading amount of the first auxiliary agent to the loading amount of the main active component is 0.25:1 to 6:1; The weight ratio of the loading amount of the second auxiliary agent to the loading amount of the main active component is 0.5:1 to 10:

1.

4. The catalyst according to claim 1, characterized in that, The specific surface area of ​​the modified carrier is 10 m². 2 / g~300m 2 / g.

5. A method for preparing the catalyst according to any one of claims 1 to 4, characterized in that, The following steps are involved: A. Prepare a mixed solution a by mixing the carrier, water, and cerium source; B. Add ammonia water to mixed solution a, dry I, calcine I to obtain the modified carrier; C. Immerse the modified carrier in water, add acid solution to adjust the pH, and obtain solution b; D. Add solution c containing the main active component precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor to solution b, dry II, and calcine II to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that, The support is selected from at least one of SiO2, Al2O3, TiO2, and MFI molecular sieve supports; Preferably, the cerium source is selected from at least one of cerium nitrate, cerium oxalate, cerium carbonate, cerium chloride, and cerium sulfate; Preferably, the acid in the acid solution includes inorganic acids and / or organic acids; The inorganic acid is hydrochloric acid; The organic acid is selected from at least one of citric acid, oxalic acid, lactic acid, malic acid, and acetic acid; Preferably, the precursor of the main active component is selected from at least one of chloroplatinic acid, ammonium chloroplatinate, and platinum tetraamminenitrate; Preferably, the first auxiliary agent precursor is selected from at least one of boric acid, gallium nitrate, gallium chloride, indium nitrate, and indium chloride; Preferably, the second auxiliary agent precursor is selected from at least one of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ferric chloride, copper chloride, zinc chloride, tungsten hexachloride, chromium chloride, molybdenum pentachloride, cobalt chloride, manganese chloride, and nickel chloride.

7. The preparation method according to claim 5, characterized in that, In step C, the pH is adjusted to 3-6; Preferably, the concentration of the ammonia solution is 1-4 mol / L, and the molar ratio of ammonia solution to cerium source is 3:1-6:1; Preferably, the mass ratio of the cerium source to the support is 1–50:100, and the cerium source is CeO₂. x For the mass calculation, x = 1 to 2; Preferably, the ratio of modified carrier to water in the modified carrier aqueous solution is 3 to 10 g / L.

8. The preparation method according to claim 5, characterized in that, The rate at which solution c is added to solution b is 5–20 mL / h; Preferably, the temperature of drying I is 20–60°C; The drying time for step I is 6–12 hours; Preferably, the calcination I is carried out in an oxygen-containing atmosphere; The temperature of calcination I is 500–600°C; The roasting time for step I is 2–12 hours; Preferably, the temperature of the drying process II is 20–60°C; The drying time for step II is 6–12 hours; Preferably, the calcination II is carried out in an oxygen-containing atmosphere; The temperature of calcination II is 500–600°C; The roasting time for the second stage is 2 to 12 hours.

9. The use of the catalyst according to any one of claims 1 to 4 in the dehydrogenation of propane to propylene, characterized in that, The process includes the following steps: contacting a feed gas containing propane and hydrogen with a reduced catalyst to react and obtain propylene.

10. The application according to claim 9, characterized in that, The reduction is carried out in an atmosphere containing hydrogen. The hydrogen-containing atmosphere has a hydrogen volume content of 10-50%. The reduction temperature is 450–600°C; The reduction time is 2 to 5 hours; Preferably, the reaction temperature is 450℃~600℃, the reaction pressure is 0.05~0.5MPa, and the weight hourly space velocity of propane is 6~20h. -1 The hydrogen-to-hydrogen molar ratio is 0.25:1 to 10:1; Preferably, the reaction is carried out in a fixed-bed reactor.

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