Catalyst for dehydrogenation of propane and preparation method and application thereof

Abstract

The application belongs to the field of catalysts, and particularly discloses a catalyst for propane dehydrogenation, a preparation method and application thereof.The catalyst for propane dehydrogenation has a high content of Cr oxides, which are uniformly distributed inside and outside the catalyst, significantly improving the catalytic activity of the catalyst in propane dehydrogenation to propylene and the selectivity of propylene, and the oxides of W, Zr and alkali metals in the catalyst can synergistically adjust the acidity and Cr2O3 redox capacity of the catalyst, thereby reducing the carbon deposition of the catalyst and improving the selectivity and yield of propylene of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to a catalyst for propane dehydrogenation, its preparation method, and its application. Background Technology

[0002] Propylene, as an important industrial raw material, is commonly used in the production of various chemicals such as propylene oxide, acrylonitrile, and polypropylene. For the past few decades, propylene has primarily been obtained through fluidized bed catalytic cracking and steam cracking, but these methods can no longer meet the growing demand for propylene. PDH technology, due to its ability to directly generate propylene and its significant advantages in propylene yield and economics, has been widely adopted by industry. In particular, Lummus's Catofin process and UOP's Oleflex process are widely used.

[0003] The Catofin process uses a Cr2O3 / Al2O3 catalyst with a Cr2O3 loading of 15-24 wt.%. However, high-loading Cr2O3 / Al2O3 catalysts have several serious problems: (1) The overall uniformity of the catalyst is poor, and the active species Cr2O3 is poorly dispersed on the surface of the Al2O3 support. Under high-temperature reaction conditions, Cr species are prone to aggregation and sintering, which leads to a decrease in catalyst activity and poor stability; (2) The interaction between the active species Cr and the support Al2O3 in the supported Cr2O3 / Al2O3 catalyst is small, and carbon deposition is serious during the reaction, which reduces the propylene selectivity of the catalyst. Summary of the Invention

[0004] In view of the problems of low catalytic activity and low propylene selectivity of supported Cr2O3 / Al2O3 catalysts in the prior art, the present invention will provide a catalyst for propane dehydrogenation and its application.

[0005] To achieve the above objectives, the following technical solutions are specifically included: In a first aspect, a catalyst for propane dehydrogenation comprises the following components in mass percentage: 60%-78% alumina, 21%-37% chromium oxide, 0.2%-2.6% zirconium oxide, 0.1%-3% tungsten oxide, and 0.5%-2% alkali metal oxide; The preparation method of the catalyst for propane dehydrogenation includes the following steps: S1. Prepare a metal source solution by mixing aluminum source, chromium source, zirconium source, tungsten source and alkali metal source; prepare an aqueous solution of precipitant; S2. Under stirring, the aqueous solution of the metal source solution and the precipitant is added dropwise to water to carry out a precipitation reaction. The pH value of the reaction system is controlled at 8~11.5 to obtain a suspension. S3. The suspension is successively subjected to aging, filtration, washing and drying to obtain the catalyst precursor; S4. The catalyst precursor is calcined to obtain the propane dehydrogenation catalyst; the calcination temperature is greater than or equal to 650°C. The propane dehydrogenation catalyst of the present invention has a high content of Cr oxide, which is uniformly distributed inside and outside the catalyst, significantly improving the catalytic activity and selectivity of the catalyst for propane dehydrogenation to propylene. The catalyst also contains oxides of W, Zr and alkali metals, which can synergistically regulate the acidity of the catalyst and the redox ability of Cr2O3. In addition, it has a large pore size and pore volume, which can effectively reduce carbon deposition on the catalyst and improve the propylene selectivity. At the same time, considering the above effects, the inventors of the present invention have found that when the contents of the support alumina, Cr, W, Zr and alkali metal oxides in the catalyst meet the above-mentioned content requirements, the selectivity and yield of the catalyst in propane dehydrogenation to propylene are even better.

[0006] Meanwhile, in the preparation method of the catalyst of the present invention, an aluminum source, a trivalent chromium source, a tungsten source, a zirconium source, and an alkali metal source are first co-precipitated to form a precursor; then, after calcination, the catalyst of the present invention is obtained. Unlike the traditional impregnation method, which relies on the surface area of ​​the support to load active species, the propane dehydrogenation catalyst of the present invention synthesizes the support and active species simultaneously. The amount of the active substance Cr can be adjusted over a very wide range. Furthermore, because the catalyst is produced by homogeneous solution precipitation, the dispersion uniformity of each component is higher, which is beneficial to enhancing the interaction between the active substance Cr and Al2O3 and the promoters (Zr, W, alkali metals), thereby improving the catalyst's dehydrogenation activity and propylene selectivity, and reducing the reduction in catalyst performance due to uneven distribution of catalyst components. In addition, the preparation method adopts a method of simultaneous preparation of the support, active components, and promoters, reducing the support preparation and calcination process, thus simplifying the process.

[0007] In one embodiment, the mass percentage of the alumina is 60%-78%, specifically 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, or any range of two of these values.

[0008] In one embodiment, the mass percentage of the chromium oxide is 21%-37%, specifically 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, or any combination of these values.

[0009] In one embodiment, the tungsten oxide has a mass percentage of 0.1%-3%, specifically 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, 2.7%, 2.9%, 3%, or any range of two of these values.

[0010] In one embodiment, the zirconium oxide has a mass percentage of 0.2%-2.6%, specifically 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, or any range of two of these values.

[0011] In one embodiment, the mass percentage of the alkali metal oxide is 0.5%-2%, specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any range of two of these values.

[0012] Secondly, the present invention provides a method for preparing the catalyst for propane dehydrogenation, comprising the following steps: S1. Prepare a metal source solution by mixing aluminum source, chromium source, zirconium source, tungsten source and alkali metal source; prepare an aqueous solution of precipitant; S2. Under stirring, the aqueous solution of the metal source solution and the precipitant is added dropwise to water to carry out a precipitation reaction. The pH value of the reaction system is controlled at 8~11.5 to obtain a suspension. S3. The suspension is successively subjected to aging, filtration, washing and drying to obtain the catalyst precursor; S4. The catalyst precursor is calcined to obtain the propane dehydrogenation catalyst; the calcination temperature is greater than or equal to 650°C.

[0013] Preferably, in step S1, the aluminum source includes at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminate, or tetrahydroxyaluminate.

[0014] Preferably, in step S1, the chromium source includes a trivalent chromium source, which comprises at least one of chromium nitrate, chromium acetate, chromium oxalate, chromium sulfate, chromate, dichromate, or chromium oxide. This method uses Cr... 3+ Use chromium source, do not use Cr 6+ This greatly reduces water pollution and lowers the cost and difficulty of wastewater treatment.

[0015] Preferably, in step S1, the zirconium source includes a zirconium salt or a zirconium oxide, and the zirconium salt includes at least one of zirconium nitrate, zirconium carbonate, zirconium basic carbonate, zirconium sulfate, or zirconate.

[0016] Preferably, in step S1, the alkali metal source includes a salt of an alkali metal or an oxide of an alkali metal, wherein the alkali metal salt includes at least one of an alkali metal halide, sulfate, carbonate, nitrate, phosphate, chromate, tungstate, aluminate, aluminate, and zirconate.

[0017] More preferably, the amounts of Al, Cr, Zr, W and alkali metal elements contained in the metal source solution prepared from the aluminum source, chromium source, zirconium source, tungsten source and alkali metal source are respectively calculated based on the weight parts of aluminum oxide, chromium oxide, zirconium oxide, tungsten oxide and alkali metal oxide, and the ratios of the amounts of Al, Cr, Zr, W and alkali metal elements are 58-92, 17-41, 0.1-3, 0.05-3.2 and 0.4-2.5, respectively. More preferably, the ratios are 60-90, 20-40, 0.2-2.6, 0.1-3 and 0.5-2.

[0018] More specifically, when the aluminum source is aluminum nitrate nonahydrate, the chromium source is chromium nitrate nonahydrate and sodium chromate, the zirconium source is zirconium nitrate pentahydrate, the tungsten source is sodium tungstate, and the alkali metal source is sodium chromate and sodium tungstate, the mass ratio of aluminum nitrate nonahydrate, chromium nitrate nonahydrate, zirconium nitrate pentahydrate, sodium chromate, and sodium tungstate is 120-150:20-40:0.1-2:0.1-0.5:0.2-0.8.

[0019] Preferably, in step S1, the tungsten source includes at least one of tungstate, metatungstate, or acetate.

[0020] Preferably, in step S1, the precipitant in the aqueous solution of the precipitant is selected from at least one of ammonia, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0021] Preferably, in step S1, the concentration of the precipitant in the aqueous solution of the precipitant is 0.1-1.5 mol / L, specifically 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, or any range of two of these values.

[0022] Preferably, in step S2, the dripping rate is 0.1-10 mL / min, specifically 0.1 mL / min, 1 mL / min, 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, 6 mL / min, 7 mL / min, 8 mL / min, 9 mL / min, 10 mL / min, or any range of two of these values.

[0023] Preferably, in step S2, the temperature of the precipitation reaction is 10-90℃, specifically 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or any combination of these values; the pH value of the precipitation reaction system is 8-11.5, specifically 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, or any combination of these values.

[0024] Preferably, in step S3, the aging temperature is 30-90℃, specifically 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or any combination of these values; the aging time is 2-10 hours.

[0025] Preferably, in step S3, the number of times the washing is performed is 1-13.

[0026] Preferably, in step S3, the drying temperature is 120-200℃, specifically 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, etc., or any range of two of these values; the drying time is 5-24 hours.

[0027] Preferably, in step S4, the roasting temperature is 700-800℃, specifically 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, or any range of two of these values; the roasting time is 2-6h, specifically 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any range of two of these values.

[0028] Preferably, the catalyst has a BET specific surface area of ​​70-150 m². 2 / g, BJH has an average pore size of 6-8nm and an average pore volume of 0.15-0.25cm³.3 / g.

[0029] Thirdly, the present invention provides a method for producing propylene from propane by dehydrogenation, comprising the following steps: placing the catalyst in a reactor, activating the catalyst by introducing hydrogen into the reactor, then introducing propane into the reactor to carry out a dehydrogenation reaction, and after the dehydrogenation reaction is completed, obtaining the catalyst after the dehydrogenation reaction and the dehydrogenation reaction product.

[0030] Preferably, the activation temperature is 500-700℃ and the activation time is 1-10 min.

[0031] Preferably, the dehydrogenation reaction temperature is 500-700℃, the dehydrogenation reaction time is 0.5-48 h, the dehydrogenation reaction pressure is 0.01-0.1 MPa, the hydrogen flow rate is 10-80 mL / min, the propane flow rate is 10-80 mL / min, and the propane space velocity is 0.5-2 h⁻¹. -1 Furthermore, after the catalyst undergoes multiple dehydrogenation reactions, air can be introduced to regenerate the catalyst at 500-700℃ for 2-10 minutes.

[0032] When the catalyst of the present invention is used as a catalyst for the dehydrogenation of propane to produce propylene, it can effectively improve the conversion rate of propane and the selectivity of propylene.

[0033] Compared with the prior art, the present invention has the following beneficial effects: The propane dehydrogenation catalyst of the present invention has a high content of Cr oxide, which is uniformly distributed inside and outside the catalyst, significantly improving the catalytic activity and selectivity of the catalyst for propane dehydrogenation to propylene. In addition, the catalyst also contains oxides of W, Zr and alkali metals, which can synergistically regulate the acidity of the catalyst and the redox ability of Cr2O3, thereby reducing the carbon deposition of the catalyst and improving the propylene selectivity and yield of the catalyst. Attached Figure Description

[0034] Figure 1 The XRD patterns are those of Example 1 and Comparative Example 1.

[0035] Figure 2 The XRD patterns are those of Example 7, Example 22, Comparative Example 5, Comparative Example 6 and Comparative Example 10. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0037] Example 1 A method for preparing a catalyst for propane dehydrogenation includes the following steps: S1. Weigh 147.11g of aluminum nitrate nonahydrate, 25.6g of chromium nitrate nonahydrate, 0.42g of zirconium nitrate pentahydrate, 0.26g of sodium chromate, and 0.25g of sodium tungstate, and add them to 100mL of deionized water to obtain a homogeneous metal source solution; ammonium carbonate is used as the precipitant, and a homogeneous 0.2mol / L ammonium carbonate solution is prepared; prepare 100mL of deionized water. S2. Stir at 50 rpm, then simultaneously add the metal source solution and 200 mL of ammonium carbonate solution dropwise to 100 mL of deionized water at a rate of 5 mL / min to carry out the precipitation reaction, and keep the pH of the reaction system at 10. S3. After the addition is complete, the temperature of the suspension is controlled at 45℃, and the stirring is kept constant for aging for 9 hours. After aging, the filter cake is obtained by filtration, washed three times with deionized water, and dried at 120℃ for 8 hours to obtain the catalyst precursor. S4. Finally, the catalyst precursor is fed into a muffle furnace and calcined at 700°C in air atmosphere for 6 hours to obtain a catalyst for propane dehydrogenation.

[0038] Example 2-32 The preparation process of Examples 2-32 is the same as that of Example 1. For relevant information and differences, please refer to Table 1 and Table 2. It should be noted that in Examples 20-22, when the type of precipitant is changed in step S2, the pH value of the reaction system is kept constant.

[0039] Comparative Example 1 171.3 g of aluminum nitrate nonahydrate was weighed and calcined at 720 °C for 3 h to obtain an Al2O3 support. 12.8 g of chromium nitrate nonahydrate, 0.42 g of zirconium nitrate pentahydrate, 0.26 g of sodium chromate, and 0.25 g of sodium tungstate were weighed and added to 10 mL of deionized water to obtain impregnation solution a. Impregnation solution a was added to the Al2O3 support prepared above, and ultrasonic impregnation was performed for 30 min. The mixture was then dried in an oven at 120 °C for 8 h and finally calcined in a muffle furnace at 700 °C for 6 h to obtain the catalyst.

[0040] Comparative Example 2 147.11 g of aluminum nitrate nonahydrate was weighed and calcined at 720 °C for 3 h to obtain an Al2O3 support. 25.6 g of chromium nitrate nonahydrate, 0.5 g of zirconium nitrate pentahydrate, 0.26 g of sodium chromate, and 0.25 g of sodium tungstate were weighed and added to 10 mL of deionized water to obtain impregnation solution a. Impregnation solution a was added to the Al2O3 support prepared above, and ultrasonic impregnation was performed for 30 min. The mixture was then dried in an oven at 120 °C for 8 h and finally calcined in a muffle furnace at 700 °C for 6 h to obtain the catalyst.

[0041] Comparative Example 3-11 The preparation process of Comparative Examples 3-11 is the same as that of Example 1, as detailed in Tables 1 and 2.

[0042] Application examples The catalysts prepared in the above examples and comparative examples are applied to the process of propane dehydrogenation to propylene, specifically including the following steps: The catalysts in the above examples and comparative examples were pressed into tablets and sieved, and 40-60 mesh catalyst particles were taken and tested for propane dehydrogenation reaction.

[0043] The reactivity and selectivity of the propane dehydrogenation catalyst were evaluated using a negative pressure fixed-bed reactor, with the gas flow rate controlled by a mass flow meter. 5g of catalyst particles (40-60 mesh) were weighed and loaded into a φ18×2mm quartz reaction tube, and the following steps were performed sequentially: (a) reduction at 600℃ in a hydrogen atmosphere (42mL / min) for 3min; (b) subsequently, the vacuum pump was turned on to reduce the system pressure to 0.05MPa (absolute pressure), and the propane feed gas was switched to 42mL / min for the dehydrogenation reaction, controlling the reaction pressure at 0.05MPa, the temperature at 600℃, and the propane space velocity at 1h. -1 The single reaction time is 15 min, with a 5 min interval. The composition and content of the outlet gas are detected by an online gas chromatograph, and the propane conversion rate (C), propylene yield (Y) and propylene selectivity (S) in each detection are calculated according to the following formulas (1) to (3); (c) After the single dehydrogenation reaction is completed, it is regenerated at 600℃ for 5 min in an air atmosphere (500 mL / min); (d) The process of steps (a) to (c) above is repeated. The average value of the propane conversion rate (C), propylene yield (Y) and propylene selectivity (S) in each cycle is taken as the catalytic effect of the catalyst in that cycle. Each sample is cycled 200 times, and the average value of the catalytic effect of a total of 200 cycles is taken as the evaluation of the overall catalytic effect of the catalyst. The specific results are shown in Table 2. Calculate propane conversion (C), propylene yield (Y), and propylene selectivity (S) according to formulas (1) to (3): C=(M0-M1) / M0×100%(1); S=M2 / (M0-M1)×100%(2); Y = M2 / M0 × 100% (3); Where M0 is the mass ratio of propane in a single feed, M1 is the mass ratio of propane in the effluent, and M2 is the mass ratio of propylene.

[0044] Performance testing: (1) Nitrogen adsorption-desorption test: A TriStar II PLUS 3030 physical adsorption instrument from Altamira, USA was used. 0.2g of catalyst was weighed and pretreated at 300℃ under vacuum for 6-8 hours to remove surface adsorbates. Nitrogen was used as the test gas. The specific surface area was calculated using the BET method, and the average pore size and pore volume were calculated using the BJH model and desorption curves.

[0045] (2) X-ray diffraction (XRD) analysis and testing: A Rigaku Uitima IV X-ray diffractometer was used, Cu-Kα, λ=0.154nm, tube voltage and current were 40kV and 40mA respectively, scanning range 2θ=10°~90°, scanning rate 2° / min.

[0046] (3) The content of each metal oxide in the catalyst was tested by XRF.

[0047] Table 1 Continued from Table 1 Continued from Table 1 Table 2 Continued from Table 2 Table 3 Depend on Figure 1-2 It can be seen that the diffraction peaks at positions of 19.5°, 32.4°, 37.7°, 39.4°, 45.9°, 60.7°, 66.7°, and 84.9° belong to β-Al₂O₃, while the diffraction peaks at 24.5°, 33.7°, 36.4°, 41.6°, 50.4°, 55°, 58.6°, 63.5°, 65.3°, 73°, 77.1°, 79.1°, and 86.7° belong to Cr₂O₃. ZrO₂, WO₃, and alkali metal oxides (Na₂O) are all amorphous. Furthermore, from... Figure 1A comparison of Example 1 and Comparative Example 1 shows that the intensity of the Cr2O3 diffraction peaks at 24.5°, 24.5°, 33.7°, 36.4°, 41.6°, 50.4°, and 55° is significantly higher than that of Comparative Example 1. This indicates that the Cr2O3 in the catalyst of Example 1 has a higher degree of crystallinity than that in Comparative Example 1, and the catalyst of the present invention is more conducive to improving the catalytic effect of propane conversion. Furthermore, the inventors found that the intensities of the Cr2O3 diffraction peaks in Comparative Examples 5, 6, and 10 are also significantly lower than those in Examples 1, 7, and 22, further demonstrating that the catalyst of the present invention has a higher degree of Cr2O3 crystallinity than the comparative examples, which is more conducive to improving the catalytic effect of propane conversion.

[0048] Comparative analysis of Example 1, Comparative Examples 1-2, and Comparative Example 6 shows that, compared to traditional impregnation-supported active component preparation methods, the catalyst preparation method of the present invention first forms a precursor by co-precipitating aluminum, trivalent chromium, tungsten, zirconium, and alkali metal sources; then, after calcination, the catalyst of the present invention is obtained. Unlike traditional impregnation methods that rely on the surface area of ​​a support to load active species, the propane dehydrogenation catalyst of the present invention synthesizes the support and active species simultaneously. The amount of the active substance Cr can be adjusted over a very wide range. Furthermore, because the catalyst is produced by precipitation from a homogeneous solution, the dispersion uniformity of each component is higher, which is beneficial for enhancing the interaction between the active substance Cr and Al2O3 and the promoters, thereby improving the catalyst's dehydrogenation activity and propylene selectivity, and reducing the reduction in catalyst performance due to uneven distribution of catalyst components.

[0049] Analysis of Examples 18-32 and Comparative Examples 3-10 reveals that the type and content of alkali metals primarily affect the selectivity of the catalyst by adjusting its surface properties; the contents of Zr and W affect the surface acidity and the number of acid sites on the catalyst, thus influencing both its activity and selectivity; Cr is the active species in the reaction and directly determines the catalyst's reactivity. More crucially, the synergistic regulation of the catalyst's acidity and the redox capacity of Cr₂O₃ among these species reduces carbon deposition, thus maintaining both high reactivity and high selectivity, ultimately leading to a catalyst with a high propylene yield.

[0050] As can be seen from Examples 1-4, the temperature during the drying process affects the reaction performance and selectivity of the catalyst. This is mainly because the degree of decomposition of the precipitates on the catalyst surface varies during the drying process. A small amount of ammonium carbonate can subtly adjust the state of the active oxide species on the catalyst surface during the catalyst calcination process, thereby changing the catalyst's reaction performance.

[0051] Comparative Examples 10-17 illustrate the effect of precipitant conditions on catalyst synthesis. The concentration of the precipitant and the pH value of the precipitation reaction both affect the uniformity of the catalyst, mainly due to differences in the precipitation rates of each component. In addition, the aging temperature and time after precipitation formation affect the particle size growth of each precipitated component, which in turn affects the interaction forces between the components of the final catalyst during calcination, thus affecting its catalytic effect.

[0052] As can be seen from Examples 1 and 20-22, the different precipitants directly affect the precipitated species formed. At the same time, the dispersion of other elements introduced during the precipitation process will also vary with each component. There are huge differences between hydroxide precipitation and carbonate precipitation in terms of decomposition temperature and decomposition products, which affects the dispersion of Cr species in the catalyst and the interaction force between Cr species and other metal oxides.

[0053] Furthermore, as can be seen from Examples 1, 5-9 and Comparative Example 11, the surface state of the catalyst is different due to the different decomposition products generated during the calcination process. Therefore, the activity and selectivity of the catalyst are different.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A catalyst for propane dehydrogenation, characterized in that, It comprises the following components by mass percentage: 60%-78% alumina, 21%-37% chromium oxide, 0.2%-2.6% zirconium oxide, 0.1%-3% tungsten oxide, and 0.5%-2% alkali metal oxide; The preparation method of the catalyst for propane dehydrogenation includes the following steps: S1. Prepare a metal source solution by mixing aluminum source, chromium source, zirconium source, tungsten source and alkali metal source; prepare an aqueous solution of precipitant; S2. Under stirring, the aqueous solution of the metal source solution and the precipitant is added dropwise to water to carry out a precipitation reaction. The pH value of the reaction system is controlled at 8~11.5 to obtain a suspension. S3. The suspension is successively subjected to aging, filtration, washing and drying to obtain the catalyst precursor; S4. The catalyst precursor is calcined to obtain the propane dehydrogenation catalyst. The roasting temperature is greater than or equal to 650°C.

2. The catalyst for propane dehydrogenation as described in claim 1, characterized in that, BET has a specific surface area of ​​70-150 m². 2 / g, BJH has an average pore size of 6-8nm and an average pore volume of 0.15-0.25cm³. 3 / g.

3. A method for preparing a propane dehydrogenation catalyst according to claim 1 or 2, characterized in that, Includes the following steps: S1. Prepare a metal source solution by mixing aluminum source, chromium source, zirconium source, tungsten source and alkali metal source; prepare an aqueous solution of precipitant; S2. Under stirring, the aqueous solution of the metal source solution and the precipitant is added dropwise to water to carry out a precipitation reaction. The pH value of the reaction system is controlled at 8~11.5 to obtain a suspension. S3. The suspension is successively subjected to aging, filtration, washing and drying to obtain the catalyst precursor; S4. The catalyst precursor is calcined to obtain the propane dehydrogenation catalyst. The roasting temperature is greater than or equal to 650°C.

4. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, In step S4, the roasting temperature is 700-800℃ and the roasting time is 2-6 hours.

5. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, In step S3, the aging temperature is 30-90℃, the aging time is 2-10h, the number of washing cycles is 1-13, the drying temperature is 120-200℃, and the drying time is 5-24h.

6. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, In step S2, the temperature of the precipitation reaction is 10-90℃.

7. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, Includes at least one of the following A and B: A. In step S1, the aluminum source includes at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminate, or tetrahydroxyaluminate. B. In step S1, the chromium source includes a trivalent chromium source, which includes at least one of chromium nitrate, chromium acetate, chromium oxalate, chromium sulfate, chromate, dichromate, or chromium oxide.

8. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, Includes at least one of the following CE markings: C. In step S1, the zirconium source includes a zirconium salt or a zirconium oxide, and the zirconium salt includes at least one of zirconium nitrate, zirconium carbonate, zirconium basic carbonate, zirconium sulfate or zirconate. D. In step S1, the alkali metal source includes a salt of an alkali metal or an oxide of an alkali metal, wherein the alkali metal salt includes at least one of an alkali metal halide, sulfate, carbonate, nitrate, phosphate, chromate, tungstate, aluminate, aluminate, and zirconate. E. In step S1, the tungsten source includes at least one of tungstate, metatungstate, or acetate.

9. The method for preparing the catalyst for propane dehydrogenation as described in claim 3, characterized in that, Includes at least one of the following FH: F. In step S1, the precipitant in the aqueous solution of the precipitant is selected from at least one of ammonia, ammonium carbonate, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. G. In step S1, the concentration of the precipitant in the aqueous solution of the precipitant is 0.1-1.5 mol / L; H. In step S2, the dripping rate is 0.1-10 mL / min.

10. A method for producing propylene by propane dehydrogenation, characterized in that, The process includes the following steps: placing the catalyst according to claim 1 or 2 in a reactor, activating the catalyst by introducing hydrogen into the reactor, then introducing propane into the reactor to carry out a dehydrogenation reaction, and after the dehydrogenation reaction is completed, obtaining the catalyst after the dehydrogenation reaction and the dehydrogenation reaction product.

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