Dehydrogenation catalyst supports and catalysts therefor, related methods of making and use

Abstract

The application provides a dehydrogenation catalyst carrier, which is a composite oxide carrier and has a molecular formula of: X a Y b ZnAl2O δ , wherein X is at least one of IIA elements; Y is at least one of IVB elements; a is 0.05-0.15; b is 0.05-0.15; and δ is the total number of oxygen atoms required to meet the valence of each element in the active component. The application further provides a dehydrogenation catalyst, which comprises an active component and the dehydrogenation catalyst carrier; wherein the active component comprises Pt elements, Cr elements and any one of Cu elements, Zn elements or Mn elements. The application solves the technical problem that the Pt loading in the catalyst is high and the conversion rate of the catalyst is reduced after multiple carbon burning in the existing process of preparing low-carbon olefins by dehydrogenation of low-carbon alkanes. The application improves the performance and selectivity of the dehydrogenation catalyst, and the spinel and perovskite structures reduce the loading of the noble metal Pt.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a dehydrogenation catalyst support and its catalyst, related preparation methods and applications. Background Technology

[0002] Propylene is a crucial organic chemical feedstock, considered alongside ethylene and isobutylene as a foundation of modern petrochemicals. Its downstream products primarily include polypropylene, epoxy alkyl acids and esters, butyric acid and esters, butanol / octanol, acrylonitrile, isobenzophenone, and epichlorohydrin. In recent years, the global supply of propylene from various fractions of naphtha and light diesel oil via steam cracking and fluidized bed catalytic cracking has been insufficient to meet the ever-growing demand, with the supply gap widening annually. Traditional methods for obtaining propylene involve co-production of ethylene and cracking processes of naphtha and light diesel oil. However, with the continuous increase in global demand for petrochemical feedstocks and products, particularly for propylene and isobutylene—fundamental petrochemical raw materials—traditional methods can no longer meet this growing demand. Therefore, scientists are dedicated to developing new routes for obtaining target propylene. Among these, the direct dehydrogenation process using propane from petrochemical byproducts or natural gas has gained significant attention in recent years, especially in regions rich in propane resources.

[0003] In recent years, with the rapid development of alkane dehydrogenation processes, alkane dehydrogenation technologies have been continuously updated and improved, and new propane dehydrogenation technologies have emerged, including Catofin, Oleflex, FBD-4, PDH, STAR, ADHO, FCDh, and -PRO. Currently, the most widely industrialized production processes are the Oleflex process from UOP (U.S.) using a Pt / Al2O3 catalyst and the Catofin process from CB&I Lummus (U.S.) using a Cr / Al2O3 catalyst. The former is expensive, while the latter is environmentally unfriendly.

[0004] Significant progress has been made in propane dehydrogenation catalysts, with research mainly focusing on the optimization of Pt-based catalysts. The Pt content of the active component in these catalysts is generally around 0.3–0.6%, and there are few reports on methods to reduce the Pt content while maintaining high catalyst stability.

[0005] Sun Chenglin et al. disclosed a propane dehydrogenation catalyst, its preparation method, and its application in patent CN108014795A. The catalyst uses θ-Al₂O₃ as a support, with metal components loaded on the support. Pt and In are essential components, while K and / or Ga are either supported as auxiliary agents or not. The elemental composition of Pt is 0.005–0.2% of the weight of the θ-Al₂O₃ support, In is 0.1–2.0% of the weight of the θ-Al₂O₃ support, K ​​is 0–2.0% of the weight of the θ-Al₂O₃ support, and Ga is 0–2.0% of the weight of the θ-Al₂O₃ support. This catalyst can be prepared by stepwise impregnation or co-impregnation. While this method reduces the catalyst content, the initial conversion rate is only 30%, and its performance needs further improvement.

[0006] In their paper "The Role of CeyZr1-yO2 in Propagation: Enhancing Catalytic Stability and Decreasing Coke Combustion Temperature" published in Applied Catalysis a-General 443:59-66, Bao et al. used commercially available γ-Al2O3 and prepared an Al support containing a CeZr solid solution fluorite structure by impregnation method. They then loaded Pt and Sn to prepare a Pt-Sn / CeZr-Al catalyst. They found that the cerium-zirconium solid solution enhanced the stability and improved the selectivity of the catalyst. After five coke combustions, the catalyst performance remained basically unchanged, and the selectivity was 94% after 4 hours. However, the conversion rate of the catalyst was only about 20%. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problems of high Pt loading in the catalyst and reduced catalyst conversion rate after multiple carbon burning in the existing process for dehydrogenation of low-carbon alkanes to prepare low-carbon olefins.

[0008] To achieve the above objectives, the first aspect of this invention provides a dehydrogenation catalyst support, which is a composite oxide support with the molecular formula: X a Y b ZnAl2O δ In the formula,

[0009] X is at least one of the IIA elements;

[0010] The Y is at least one of the IVB elements;

[0011] The value of a ranges from 0.05 to 0.15; the value of b ranges from 0.05 to 0.15; δ is the total number of oxygen atoms required to satisfy the oxidation states of each element in the active component.

[0012] In a specific embodiment of the present invention, the above-mentioned element IIA is Ca or Sr.

[0013] In a specific embodiment of the present invention, the above-mentioned IVB element is Ti or Zr.

[0014] A second aspect of this invention provides a method for preparing the above-mentioned dehydrogenation catalyst support, comprising the following steps:

[0015] Compounds containing elements X, Y, Zn, and Al, respectively, and urea were dissolved in deionized water containing alcohol and subjected to a hydrothermal reaction. After heating, the mixture was crystallized, filtered, dried, and calcined to obtain a compound with the molecular formula X. a Y b ZnAl2O δ Dehydrogenation catalyst support.

[0016] As a specific embodiment of the present invention, the alcohol mentioned above is ethanol or ethylene glycol.

[0017] As a specific embodiment of the present invention, the above heating step is: heating to 150-180°C at a heating rate of 2-5°C / min.

[0018] As a specific embodiment of the present invention, the crystallization time is 20-28 hours.

[0019] A third aspect of this invention provides a dehydrogenation catalyst comprising: an active component and the aforementioned dehydrogenation catalyst support or a hydrogen catalyst support prepared by the aforementioned method; wherein the active component comprises: component a, component b, and component c; wherein,

[0020] The above component a is Pt element;

[0021] Component b above is Cr element;

[0022] The above component c is Cu, Zn, or Mn.

[0023] As a specific embodiment of the present invention, the dehydrogenation catalyst includes:

[0024] 0.01 to 0.3 parts by weight of Pt element;

[0025] 0.01 to 3 parts by weight of Cr element;

[0026] 0.01 to 3 parts by weight of Cu, Zn, or Mn elements;

[0027] 95-99 parts by weight of hydrogen catalyst support.

[0028] In a specific embodiment of the present invention, the Pt element is 0.01 to 0.2 parts by weight.

[0029] In a specific embodiment of the present invention, the Cr element is 0.1 to 2 parts by weight.

[0030] As a specific embodiment of the present invention, the Cu element, Zn element or Mn element mentioned above are 0.1 to 2 parts by weight.

[0031] As a specific embodiment of the present invention, the hydrogen catalyst support is 96 to 98 parts by weight.

[0032] The aforementioned hydrogen catalyst support undergoes chemical reactions with the added Pt, Cr, Cu, Zn, and Mn elements, resulting in a stable dispersion of each element on the support surface.

[0033] As a specific embodiment of the present invention, the above-mentioned dehydrogenation catalyst is a perovskite and spinel type composite structure.

[0034] As a specific embodiment of the present invention, the XRD characteristic peak intensity ratio of the above-mentioned perovskite and spinel type composite structure is 0.1 to 0.2.

[0035] The aforementioned perovskite and spinel composite structure is formed by the atomic arrangement determined by the atomic valence state and particle size after the added elements are calcined. This perovskite and spinel composite structure is stable, thereby enhancing the stability of the catalyst.

[0036] A fourth aspect of this invention provides a method for preparing the above-mentioned dehydrogenation catalyst, comprising the following steps:

[0037] 1) Add an aqueous solution of a Cr-containing compound to the above-mentioned dehydrogenation catalyst support or the hydrogen catalyst support prepared by the above method, mix ultrasonically, dry, and calcine to obtain the catalyst precursor.

[0038] 2) Dissolve the Pt-containing compound and the Cu, Zn or Mn-containing compound in water, add the above catalyst precursor, mix ultrasonically, dry and calcine to obtain the dehydrogenation catalyst.

[0039] The compounds containing Cu, Zn, or Mn are water-soluble compounds and are not limited to nitrate compounds.

[0040] As a specific embodiment of the present invention, in steps 1) and 2) above: the drying temperature is 80 to 150°C.

[0041] As a specific embodiment of the present invention, in steps 1) and 2) above: the drying time is 6 to 24 hours.

[0042] As a specific embodiment of the present invention, in steps 1) and 2) above: the roasting temperature is 500 to 700°C.

[0043] As a specific embodiment of the present invention, in steps 1) and 2) above: the roasting time is 6 to 24 hours.

[0044] As a specific embodiment of the present invention, the ultrasound in steps 1) and 2) above is frequency conversion ultrasound;

[0045] As a specific embodiment of the present invention, the above-mentioned frequency conversion ultrasound process is as follows: ultrasound at 10 kHz for 0.5 h at room temperature, and ultrasound at 20 kHz for 1 h.

[0046] The fifth aspect of the present invention provides the use of the above-described dehydrogenation catalyst or the dehydrogenation catalyst prepared by the above-described preparation method in the dehydrogenation of low-carbon alkanes to prepare low-carbon olefins.

[0047] As a specific embodiment of the present invention, the aforementioned low-carbon alkane is propane.

[0048] The sixth aspect of this invention provides a method for preparing low-carbon olefins by dehydrogenation of low-carbon alkanes, comprising: using low-carbon alkanes as reactants, reacting them with the above-mentioned dehydrogenation catalyst or the dehydrogenation catalyst prepared by the above-mentioned preparation method to obtain low-carbon olefins.

[0049] As a specific embodiment of the present invention, the conditions for the above-mentioned contact reaction are: a water vapor to propane volume ratio of (10-1):1, a reaction temperature of 500-700°C, a reaction pressure of 0-1 MPa, and an alkane mass hourly space velocity of 3.0-8.0 h⁻¹. -1 .

[0050] In a specific embodiment of the present invention, the aforementioned low-carbon olefin is propylene.

[0051] The dehydrogenation catalyst prepared by the above method was evaluated for its activity in an isothermal fixed-bed reactor for the propane dehydrogenation to propylene system. The evaluation process included: adjusting the flow rate of propane gas through a mass flow meter, introducing it into the preheating zone for mixing, and then introducing it into the reaction zone. Both the preheating zone and the reaction zone of the reactor were heated by electric heating wires to reach a predetermined temperature. The reactor was constructed using a stainless steel sleeve with an inner diameter of Ф9mm-Ф6mm and a length of approximately 400mm. After the reaction, the gas was condensed and then analyzed by gas chromatography. The catalyst evaluation conditions in the isothermal fixed-bed reactor were as follows: approximately 0.5g of catalyst was loaded into an isothermal reactor with an inner diameter of Ф9mm-Ф6mm (catalyst bed height approximately 17mm), the volume ratio of water vapor to propane was (10~1):1, the reaction temperature was 500~700℃, the reaction pressure was 0~1MPa, and the alkane mass hourly space velocity was 3.0~8.0h. -1The reactants react with the catalyst to produce propylene.

[0052] Compared with the prior art, the present invention has at least the following advantages:

[0053] (1) For dehydrogenation catalysts, many side reactions also occur at the acid sites on the support surface, such as alkane cracking, isomerization, olefin cracking, isomerization, and polymerization reactions. A single Al2O3 is not conducive to the stability of the catalytic reaction; therefore, this invention selects oxide X. a Y b ZnAl2O δ Using Pt and Cr as the support, Cu, Zn or Mn elements can enhance the role of Pt and optimize the preparation process to strengthen the interaction between the components, thereby improving the performance of the dehydrogenation catalyst. The spinel and perovskite structures further ensure the stability of the catalyst and reduce the loading of the precious metal Pt. Compared with traditional Pt-based catalysts, it also reduces the production cost.

[0054] (2) The catalyst preparation method of the present invention uses a hydrothermal method to prepare X. a Y b ZnAl2O δ The carrier, prepared by the hydrothermal method, is a homogeneous solution, which ensures the uniformity of X, Y, Zn and Al elements, which is beneficial for the formation of composite structures and results in high crystallinity.

[0055] (3) The catalyst preparation method of the present invention adopts a variable frequency ultrasonic step, which further enhances the dispersion of impregnated Cr ions, Pt and other impregnated element ions on the surface of the support, ensuring that they fully interact with the support during the calcination process, which is beneficial to the activity of the catalyst performance. Attached Figure Description

[0056] Figure 1 The XRD diffraction patterns are those of the catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 of this invention. Detailed Implementation

[0057] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0058] Example 1: A method for preparing a dehydrogenation catalyst support

[0059] The preparation method includes:

[0060] (1) In a hydrothermal reactor, weigh 29.749 g of zinc nitrate hexahydrate, 23.615 g of calcium nitrate tetrahydrate, 18.968 g of titanium tetrachloride, 75.026 g of aluminum nitrate nonahydrate, and 42.042 g of urea and dissolve them in 400 mL of deionized water containing 8% ethylene glycol. Mix well and place in an oven for hydrothermal reaction. The temperature is increased to 180 °C at a program of 3 °C / min and crystallized for 24 h.

[0061] (2) The product was filtered and washed with 800 mL of water to obtain a filter cake. The filter cake was dried at 150 °C for 16 hours and then calcined in a muffle furnace at 650 °C for 20 hours to obtain 15.12 g of ZnCa. 0.1 Ti 0.1 Al2O δ The carrier composition is shown in Table 1.

[0062] Example 2: A method for preparing a dehydrogenation catalyst

[0063] (1) Weigh 9.758 g of ZnCa prepared in Example 1 0.1 Ti 0.1 Al2O δ The support was placed in a beaker, and then 1.154 g of chromium nitrate nonahydrate was weighed and dissolved in 10 mL of deionized water. The support was added while stirring, and the mixture was sonicated at 10 kHz for 1 h and then at 30 kHz for 2 h to mix evenly. The mixture was then impregnated at 30 °C for 12 h, dried at 150 °C for 16 h, and calcined in a muffle furnace at 650 °C for 20 h to obtain the catalyst precursor, denoted as I.

[0064] (2) Weigh 0.032 g of chloroplatinic acid and 0.226 g of copper nitrate trihydrate and dissolve them in 10 mL of deionized water. After stirring at 120 °C for 4 h, add the above catalyst precursor, sonicate at 10 kHz for 0.5 h, sonicate at 20 kHz for 1 h to mix evenly, impregnate at 30 °C for 12 h, dry at 150 °C for 16 h, and calcine in a muffle furnace at 650 °C for 20 h to obtain 10.08 g of dehydrogenation catalyst.

[0065] Example 3: A method for preparing a dehydrogenation catalyst support

[0066] The preparation method includes:

[0067] (1) In a hydrothermal reactor, weigh 29.749 g of zinc nitrate hexahydrate, 21.163 g of strontium nitrate, 18.968 g of titanium tetrachloride, 75.026 g of aluminum nitrate nonahydrate, and 42.042 g of urea and dissolve them in 400 mL of deionized water containing 8% ethylene glycol. Mix well and place in an oven for hydrothermal reaction. The temperature is increased to 160 °C at a program of 3 °C / min and crystallized for 20 h.

[0068] (2) The product was filtered and washed with 800 mL of water to obtain a filter cake. The filter cake was dried at 120 °C for 16 hours and then calcined in a muffle furnace at 680 °C for 16 hours to obtain 15.24 g of ZnSr. 0.1 Ti 0.1 Al2O δ The carrier composition is shown in Table 1.

[0069] Example 4: A method for preparing a dehydrogenation catalyst

[0070] (1) Weigh 9.785g of ZnSr prepared in Example 3 0.1 Ti 0.1 Al2O δ The support was placed in a beaker, and then 0.923 g of chromium nitrate nonahydrate was weighed and dissolved in 10 mL of deionized water. The support was added with stirring, and the mixture was sonicated at 10 kHz for 1 h and then sonicated at 30 kHz for 2 h to mix evenly. The mixture was then impregnated at 30 °C for 12 h, dried at 150 °C for 16 h, and calcined in a muffle furnace at 650 °C for 20 h to obtain the catalyst precursor, denoted as I.

[0071] (2) Weigh 0.04 g of chloroplatinic acid and 0.364 g of zinc nitrate hexahydrate and dissolve them in 10 mL of deionized water. After stirring at 120 °C for 4 h, add the above catalyst precursor, sonicate at 10 kHz for 0.5 h, sonicate at 20 kHz for 1 h to mix evenly, impregnate at 30 °C for 12 h, dry at 150 °C for 16 h, and calcine in a muffle furnace at 650 °C for 20 h to obtain 10.13 g of dehydrogenation catalyst.

[0072] Example 5: A method for preparing a dehydrogenation catalyst support

[0073] The preparation method includes:

[0074] (1) In a hydrothermal reactor, weigh 29.479 g of zinc nitrate hexahydrate, 23.615 g of calcium nitrate tetrahydrate, 33.924 g of zirconium nitrate pentahydrate, 75.026 g of aluminum nitrate nonahydrate, and 42.042 g of urea and dissolve them in 400 mL of deionized water containing 8% ethylene glycol. Mix well and place in an oven for hydrothermal reaction. The temperature is increased to 150 °C at a program of 3 °C / min and crystallized for 22 h.

[0075] (2) The product was filtered and washed with 800 mL of water to obtain a filter cake. The filter cake was dried at 130 °C for 18 hours and then calcined in a muffle furnace at 700 °C for 15 hours to obtain 15.38 g of ZnCa. 0.1 Zr 0.1 Al2O δ The carrier composition is shown in Table 1.

[0076] Example 6: A method for preparing a dehydrogenation catalyst

[0077] (1) Weigh 9.71g of the dehydrogenation catalyst support prepared in Example 5 and put it into a beaker. Then weigh 1.539g of chromium nitrate nonahydrate and dissolve it in 10mL of deionized water. Add the above support while stirring. Sonicate at 10 kHz for 1h and at 30 kHz for 2h to mix evenly. Impregnate at 30℃ for 12h. Then dry at 150℃ for 16h and calcine in a muffle furnace at 650℃ for 20h to obtain the catalyst precursor, denoted as I.

[0078] (2) Weigh 0.267 g of chloroplatinic acid and 0.366 g of manganese nitrate tetrahydrate and dissolve them in 10 mL of deionized water. After stirring at 120 °C for 4 h, add the above catalyst precursor, sonicate at 10 kHz for 0.5 h, sonicate at 20 kHz for 1 h to mix evenly, impregnate at 30 °C for 12 h, dry at 150 °C for 16 h, and calcine in a muffle furnace at 650 °C for 20 h to obtain 10.05 g of dehydrogenation catalyst.

[0079] Comparative Example 1: A method for preparing a dehydrogenation catalyst

[0080] ZnCa dehydrogenation catalyst support obtained in Example 1 0.1 Ti 0.1 Al2O δ A dehydrogenation catalyst was obtained by loading only the active component Cr, without loading platinum and copper elements, and otherwise the same as in Example 2.

[0081] Comparative Example 2: A method for preparing a dehydrogenation catalyst

[0082] ZnCa dehydrogenation catalyst support obtained in Example 1 0.1 Ti 0.1 Al2O δ A dehydrogenation catalyst was obtained by loading only the active components Pt and Cr, without loading copper. The rest is the same as in Example 2.

[0083] Comparative Example 3: A method for preparing a dehydrogenation catalyst support

[0084] In the preparation of the catalyst in this comparative example, calcium nitrate tetrahydrate and titanium tetrachloride were not added, and hydrothermal reaction was not used. Everything else was the same as in Example 1.

[0085] (1) Weigh 29.749g of zinc nitrate and 75.026g of aluminum nitrate soluble salt and dissolve them in 1L of deionized water and mix them evenly; slowly add ammonia water dropwise while stirring continuously, adjust the pH value to 7.6, age the product for 2 hours, and filter and wash with 4L of water to obtain filter cake.

[0086] (3) After drying the filter cake at 150°C for 16 hours, it was calcined in a muffle furnace at 650°C for 20 hours to obtain 14.66g of ZnAl2O4 support.

[0087] Comparative Example 4: A method for preparing a dehydrogenation catalyst support

[0088] In the preparation of the catalyst in this comparative example, calcium nitrate tetrahydrate and titanium tetrachloride were not added, and the other preparation processes were the same as in Example 1, resulting in the dehydrogenation catalyst support ZnAl2O4.

[0089] Comparative Example 5: A method for preparing a dehydrogenation catalyst

[0090] ZnCa in Example 2 0.1 Ti 0.1 Al2O δ The support was replaced with the ZnAl2O4 support obtained in Comparative Example 3, and everything else was the same as in Example 2 to prepare the dehydrogenation catalyst.

[0091] Comparative Example 6: A method for preparing a dehydrogenation catalyst

[0092] ZnCa in Example 2 0.1 Ti 0.1 Al2O δ The support was replaced with the ZnAl2O4 support obtained in Comparative Example 4, and everything else was the same as in Example 2 to prepare the dehydrogenation catalyst.

[0093] Comparative Example 7: A method for preparing a dehydrogenation catalyst

[0094] The dehydrogenation catalyst was prepared by loading only platinum and chromium active components onto the ZnAl2O4 support obtained in Comparative Example 3, without using the frequency conversion ultrasonic method.

[0095] Comparative Example 8: A method for preparing a dehydrogenation catalyst

[0096] The ZnAl2O4 support obtained in Comparative Example 3 was combined only with the platinum active component, and no frequency conversion ultrasound method was used.

[0097] The preparation method includes the following steps: weighing 9.988 g of ZnAl2O4 support and placing it in a beaker, dissolving 0.032 g of chloroplatinic acid in 10 mL of water, adding the solution to the support while stirring, mixing thoroughly, impregnating at 30°C for 12 hours, drying at 150°C for 16 hours, and calcining in a muffle furnace at 650°C for 20 hours to obtain the dehydrogenation catalyst. The catalyst evaluation is the same as in Example 1, and the results are shown in Table 1.

[0098] Test example:

[0099] The catalyst evaluation conditions are as follows: 0.5 g of dehydrogenation catalyst was charged into the above-mentioned isothermal fixed-bed reactor (catalyst bed height 17 mm), the reaction was carried out at atmospheric pressure and temperature 550 °C; the volume ratio of water vapor to propane was 3:1; and the propane mass hourly space velocity was 3.0 h⁻¹. -1The results are shown in Table 1. The dehydrogenation catalyst was regenerated by carbonization for 2 hours after reacting for 10 hours. The reaction results after 50 regenerations are shown in Table 1.

[0100] Table of Dehydrogenation Catalyst Evaluation Indicators

[0101]

[0102]

[0103] As can be seen from the table above, Comparative Examples 5, 6, 7, and 8 did not use the molecular formula XYZnAlO δ ZnCa catalyst support 0.1 Ti 0.1 Al2O δ The catalyst support used is ZnAl2O4, which does not contain calcium nitrate tetrahydrate and titanium tetrachloride, and does not possess XYZnAlO4. δ Molecular formula structure.

[0104] Comparative Example 6 used a catalyst supported by ZnAl2O4 prepared via hydrothermal reaction and composed of active components A, B, and C. Its conversion rate was 36.1%, and the catalyst selectivity was 93.8%, which was lower than that of the catalyst supported by ZnCa prepared via hydrothermal reaction in Example 2 under the same conditions. 0.1 Ti 0.1 Al2O δ The obtained catalyst had a conversion rate of 39.7% and a selectivity of 94.5%. Comparative Examples 7 and 8 both used ZnAl₂O₄ catalyst supports prepared without hydrothermal reaction, with Comparative Example 7 not loading component C and Comparative Example 8 not loading components Cr and C. Consequently, Comparative Example 7 achieved a conversion rate of 31.4% and a catalyst selectivity of 92.3%, while Comparative Example 8 achieved a conversion rate of only 19.8% and a catalyst selectivity of 89.5%, significantly lower than the 39.7% conversion rate and 94.5% selectivity in Example 2. Therefore, the catalyst support ZnAl₂O₄ prepared using the hydrothermal method is superior. 0.1 Ti 0.1 Al2O δ This support ensures the catalyst possesses spinel and perovskite structures, guaranteeing catalyst stability and reducing Pt loading; simultaneously, this catalyst support, ZnCa... 0.1 Ti 0.1 Al2O δ The loading of Pt and Cr as dual dehydrogenation centers further improved the catalyst conversion and selectivity.

[0105] Comparative Examples 1 and 2 used the same catalyst support ZnCa as in Example 2. 0.1 Ti 0.1 Al2Oδ Compared with Example 2, which did not support component C, the catalyst obtained had a conversion rate and selectivity of 36.8% and 92.8%, respectively, which were lower than those of Example 2 (39.7% and 94.5%). This shows that component C (Cu, Zn, or Mn elements) can enhance the role of Pt and improve the overall dehydrogenation performance of the catalyst.

[0106] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A dehydrogenation catalyst support, characterized in that, The dehydrogenation catalyst support is a composite oxide support with the molecular formula: X a Y b ZnAl2O δ In the formula, X is at least one of the IIA elements; The Y is at least one of the IVB elements; The value of a ranges from 0.05 to 0.15; the value of b ranges from 0.05 to 0.15; δ is the total number of oxygen atoms required to satisfy the oxidation states of each element in the active component; The preparation method of the dehydrogenation catalyst support includes the following steps: dissolving compounds containing elements X, Y, Zn, and Al, respectively, and urea in water containing alcohol for hydrothermal reaction; After heating, the catalyst is crystallized, filtered, dried, and calcined to obtain the dehydrogenation catalyst support.

2. The dehydrogenation catalyst support according to claim 1, characterized in that, The IIA element is Ca or Sr; and / or, the IVB element is Ti or Zr.

3. A method for preparing the dehydrogenation catalyst support according to claim 1 or 2, characterized in that, The preparation method includes the following steps: A hydrothermal reaction was carried out by dissolving compounds containing elements X, Y, Zn, and Al, respectively, and urea in water containing alcohol. After heating, the mixture crystallized, filtered, dried, and calcined to obtain a product with the molecular formula X. a Y b ZnAl2O δ Dehydrogenation catalyst support.

4. The preparation method according to claim 3, characterized in that, The alcohol is ethanol or ethylene glycol; And / or, the heating step is: to program the temperature to 150-180°C at a heating rate of 2-5°C / min; And / or, the crystallization time is 20-28 hours.

5. A dehydrogenation catalyst, characterized in that, The dehydrogenation catalyst comprises: an active component and a dehydrogenation catalyst support; wherein, the active component comprises: component a, component b, and component c; wherein, The component a is Pt element; The component b is Cr element; The component c is Cu, Zn, or Mn. The dehydrogenation catalyst support is a composite oxide support with the molecular formula: X a Y b ZnAl2O δ In the formula, X is at least one of the IIA elements; The Y is at least one of the IVB elements; The value of a ranges from 0.05 to 0.15; the value of b ranges from 0.05 to 0.15; δ is the total number of oxygen atoms required to satisfy the oxidation states of each element in the active component.

6. The dehydrogenation catalyst according to claim 5, characterized in that, The IIA element is Ca or Sr; and / or, the IVB element is Ti or Zr.

7. The dehydrogenation catalyst according to claim 5, characterized in that, The preparation method of the dehydrogenation catalyst support includes the following steps: dissolving compounds containing elements X, Y, Zn, and Al, respectively, and urea in water containing alcohol for a hydrothermal reaction; crystallizing after heating, filtering, drying, and calcining to obtain a catalyst support with the molecular formula X. a Y b ZnAl2O δ Dehydrogenation catalyst support.

8. The dehydrogenation catalyst according to claim 7, characterized in that, The alcohol is ethanol or ethylene glycol; And / or, the heating step is: to program the temperature to 150-180°C at a heating rate of 2-5°C / min; And / or, the crystallization time is 20-28 hours.

9. The dehydrogenation catalyst according to any one of claims 5-8, characterized in that, The dehydrogenation catalyst includes: 0.01 to 0.3 parts by weight of Pt element; 0.01 to 3 parts by weight of Cr element; 0.01 to 3 parts by weight of Cu, Zn, or Mn elements; 95-99 parts by weight of hydrogen catalyst support.

10. The dehydrogenation catalyst according to claim 9, characterized in that, The dehydrogenation catalyst includes: 0.01 to 0.2 parts by weight of Pt element; And / or, 0.1 to 2 parts by weight of Cr element; And / or, 0.1 to 2 parts by weight of Cu, Zn or Mn; And / or, 96 to 98 parts by weight of hydrogen catalyst support.

11. The dehydrogenation catalyst according to any one of claims 5-8, characterized in that, The dehydrogenation catalyst has a perovskite and spinel composite structure.

12. The dehydrogenation catalyst according to claim 11, characterized in that, The XRD characteristic peak intensity ratio of the perovskite and spinel composite structure is 0.1~0.

2.

13. A method for preparing a dehydrogenation catalyst according to any one of claims 5-12, comprising the following steps: 1) An aqueous solution of a Cr-containing compound is added to the dehydrogenation catalyst support, ultrasonically mixed, dried, and calcined to obtain the catalyst precursor. 2) Dissolve the Pt-containing compound and the Cu, Zn or Mn-containing compound in deionized water, add the above catalyst precursor, ultrasonically mix, dry and calcine to obtain the dehydrogenation catalyst.

14. The preparation method according to claim 13, characterized in that, In steps 1) and 2) above: The drying temperature is 80–150°C; And / or, the drying time is 6 to 24 hours. And / or, the calcination temperature is 500–700°C; And / or, the roasting time is 6 to 24 hours.

15. The preparation method according to claim 13 or 14, characterized in that, The ultrasound described in steps 1) and 2) is frequency conversion ultrasound.

16. The preparation method according to claim 15, characterized in that, The process of frequency conversion ultrasound is as follows: ultrasound at 10 kHz for 0.5 h at room temperature, and ultrasound at 20 kHz for 1 h.

17. Use of a dehydrogenation catalyst according to any one of claims 5-12 or a dehydrogenation catalyst prepared by the preparation method according to any one of claims 13-16 in the dehydrogenation of low-carbon alkanes to prepare low-carbon olefins.

18. The use according to claim 17, characterized in that, The low-carbon alkane is propane.

19. A method for preparing low-carbon olefins by dehydrogenation of low-carbon alkanes, comprising: Using low-carbon alkanes as reactants, a contact reaction is carried out with the dehydrogenation catalyst described in any one of claims 5-12 or the dehydrogenation catalyst prepared by the preparation method described in any one of claims 13-16 to obtain low-carbon olefins.

20. The method according to claim 19, characterized in that, The conditions for the contact reaction are as follows: a water vapor to propane volume ratio of (10~1):1, a reaction temperature of 500~700℃, a reaction pressure of 0~1MPa, and an alkane mass hourly space velocity of 3.0~8.0h. -1 ; And / or, the low-carbon olefin is propylene.

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